BHARATI VIDYAPEETH DEEMED UNIVERSITY, PUNE

Transcription

1 Optimisation of Coagulation Flocculation Treatment by Moringa Oleifera seed extract: influence of Physical parameters A Thesis submitted for the award of degree of DOCTOR OF PHILOSOPHY in the Faculty of Engineering & Technology (CIVIL ENGINEERING) To Grade A Accredited by NACC (2004 and 2011) BHARATI VIDYAPEETH DEEMED UNIVERSITY, PUNE (INDIA) BY Milind R. Gidde UNDER THE GUIDANCE OF Dr. Anand R. Bhalerao PROFESSOR, DEPARTMENT OF CIVIL ENGINEERING Bharati Vidyapeeth Deemed University College of Engineering Pune BHARATI VIDYAPEETH DEEMED UNIVERSITY, PUNE

2 CERTIFICATE This is to certify that the work presented in the thesis entitled Optimisation of Coagulation Flocculation Treatment by Moringa Oleifera seed extract: influence of Physical parameters for the degree of Doctor of Philosophy (Engineering & Technology) has been carried out at Bharati Vidyapeeth Deemed University, College of Engineering, Pune by Milind R. Gidde under the guidance of Dr. Anand R. Bhalerao. The material obtained and referred from other sources has been duly acknowledged in the thesis. Principal and Dean Bharati Vidyapeeth Deemed University, College of Engineering, Pune-43 Date: Place: Pune i

3 CERTIFICATE OF THE GUIDE This is to certify that the work presented in the thesis entitled Optimisation of Coagulation Flocculation Treatment by Moringa Oleifera seed extract: influence of Physical parameters for the degree of Doctor of Philosophy (Engineering & Technology) has been carried out at Bharati Vidyapeeth Deemed University, College of Engineering, Pune by Milind R. Gidde under my guidance. The material obtained and referred from other sources has been duly acknowledged in the thesis. The quality of research work is satisfactory for awarding Ph.D. degree. (Dr. Anand R. Bhalerao) Research Guide Professor, Department of Civil Engineering Bharati Vidyapeeth Deemed University College of Engineering, Pune-43 Date: Place: Pune ii

4 DECLARATION BY THE CANDIDATE I hereby declare that the thesis entitled Optimisation of Coagulation Flocculation Treatment by Moringa Oleifera seed extract: influence of Physical parameters submitted by me for the degree of Doctor of Philosophy is the record of work carried out by me during the period from July 2007 to April 2013 under the guidance of Dr. Anand R. Bhalerao and has not formed the basis of the award of any degree, diploma, associateship, fellowship, titles in this or any other university or other institutions of higher learning. I further declare that the material obtained and referred from other sources has been duly acknowledged in the thesis. (Milind R. Gidde) Research Student, Bharati Vidyapeeth Deemed University, Pune-30 Date: Place: Pune iii

5 Acknowledgements Pursuing a Ph. D. project is both a painful and enjoyable experience. It is just like climbing a high peak, step by step accompanied with bitterness, hardship, frustration, encouragement and trust and with so many people s kind help. When I found myself at the top enjoying the beautiful scenery, I realized that it was, in fact, team work that got me there. Though it will not be enough to express my gratitude in words to all those people who helped me, I would still like to give my many, many thanks to all these people. First of all I d like to give my sincere thanks to my honorific guide Prof. Dr. Anand R. Bhalerao, who accepted me as his Ph. D. student without any hesitation, when I presented him my research proposal. Thereafter, he offered me so much advice, patiently supervising me, and always guiding me in the right direction. I have learnt a lot from him, without his help I could not have finished my dissertation successfully. Special thanks are also given to Hon ble Prof. (Dr.) Shivajirao Kadam (Vice Chancellor, Bharati Vidyapeeth University, Pune) for his encouragement and help to make me feel confident to fulfill my desire and to overcome every difficulty encountered. I am also thankful to Prof. (Dr.) Mrs. V.S. Sohoni HOD (Civil), other faculty members of the department, administrative and supporting staff and the students. I am very much grateful to Dr. A.D. Patwardhan and Mr. R. M. Kshirsagar for giving suggestions during experimentation and also helping in proof reading. I would like to express my appreciation to my students Shashank Yevale, Hitesh Majethiya, Chetan Pise who helped during my experimentation work. I am also grateful to Mr. Namadeo Jadhav (B. V. College of Pharmacy, Kolhapur) for helping me in purification of crude seed powder. I would like to give my special thanks to Ms Minal Ware for guiding me in the data analysis by statistical method. iv

6 My close friends, who are too many to mention always stood by my side asking over and over again When will you get it done? Next week? Next month? Next year? When? Finally, I want to thank my parents, for their absolute confidence in me and my wife and sons for their endeavoring support and constant encouragement to complete my work. Milind R. Gidde v

7 Table of Contents Title Certificate Certificate of Guide Declaration by Candidate Acknowledgement Table of contents Abbreviations List of Photos List of Tables List of Figures Abstract Page No. i ii iii iv vi x x xi xiv xv 1 Introduction Literature Review Introduction Coagulation - Flocculation Mechanism of Coagulation Coagulants Chemicals Coagulants of Plant origin Moringa oleifera General Composition of M.O Coagulation Mechanism of M.O Aim and Objectives Materials and Methods Seed collection and Sampling Characterisation of seeds Bentonite clay Kaolin clay Preparation of stock solutions Extraction and purification of seed powder 33 vi

8 4.7 Experiment design Coagulant dose Container Geometry RMVG and SMVG Experimentation 41 5 Residual Alluminium in treated drinking water at Pune Introduction Alluminium in water supplies Water supply problems Health effects of alluminium Water requirements and supply of Pune city Sampling Results Discussions Conclusion 51 6 Results M.O. seed Analysis Optimisation of Dose Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended (SB) Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Purified Protein Observations Discussions Conclusion Optimisation of Container Geometry Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Jars CNB, CB, SNB, SB Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled Jars CNB, CB, SNB, SB Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Jars CNB, CB, SNB, SB vii

9 6.2.4 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled Jars CNB, CB, SNB, SB Discussions and Conclusion Optimisation of Rapid Mix Velocity Gradient Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended RMVG 250S -1, 329 S -1, 415 S -1, 507 S Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled RMVG 250S -1, 329 S -1, 415 S -1, 507 S Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended RMVG 250S -1, 329 S -1, 415 S -1, 507 S Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled RMVG 250S -1, 329 S -1, 415 S -1, 507 S Observations and Discussions Conclusion Optimisation of Slow Mix Velocity Gradient Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Observations and Discussions Conclusion Settling Column Study Introduction Objective of the Study Methodology Experimentation Determination of Optimum dose Settling Column Test Results Observations Conclusion Statistical Analysis Introduction Sample calculation Conclusion 135 viii 81

10 9 Conclusion Conclusion Future Study 141 List of Publications References ix

11 Abbreviations: M. O. Moringa oleifera V. G. Velocity Gradient RMVG SMVG CB CNB SB SNB Rapid Mixing Velocity Gradient Slow Mixing Velocity Gradient Circular Baffled Circular Non Baffled Square Baffled Square Non Baffled List of Photos: Sr. No. Photo No. Description Page No The Miracle Tree Moringa oleifera Seed of M.O Pods of M.O Extraction of the Active Ingredient Different types of Custom Made Jars CNB, CB, SNB, SB Digital Turbidity Meter Jar Test apparatus with jars 43 x

12 List of Tables: Sr. Table Page Description No. No. No Major impurities of natural water (Montgomery 1985) Nutritional and anti-nutritional composition of Moringa oleifera seeds The methods of seed analysis Extraction efficiency of different solvents Details of Coagulant Dose Types of Jars with their dimension rpm and its Corresponding velocity gradient Alluminium and ph of water samples Results of Seed Analysis Dose optimisation: Turbidity - Bentonite Clay (50,150,450 NTU) and 54 Extract M.O. Shelled Blended Dose optimization (M.O. Shelled Blended) Bentonite 50 NTU Dose optimization (M.O. Shelled Blended) Bentonite 150 NTU Dose optimization (M.O. Shelled Blended) Bentonite 450 NTU Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled Dose Optimization (M.O. Deoiled) Bentonite 50 NTU Dose Optimization (M.O. Deoiled) Bentonite 150 NTU Dose Optimization (M.O. Deoiled) Bentonite 450 NTU Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled 60 blended Dose Optimisation (M.O Shelled Blended) KAOLIN 50 NTU Dose Optimisation (M.O Shelled Blended) KAOLIN 150 NTU Dose Optimisation (M.O Shelled Blended) KAOLIN 450 NTU Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled Dose Optimisation (M.O. Deoiled) KAOLIN 50 NTU Dose Optimisation (M.O. Deoiled) KAOLIN 150 NTU Dose Optimisation (M. O. Deoiled) KAOLIN 450 NTU Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Purified 66 Protein Dose Optimisation (M.O. Protein Powder) at Bentonite 50 NTU Dose Optimisation (M.O. Protein Powder) at Bentonite 150 TU Dose Optimisation (M.O. Protein Powder) at Bentonite 450 TU Container Geometry optimisation: Turbidity - Bentonite Clay 72 (50,150,450 NTU) and Extract M.O. Shelled Blended Jars CNB, CB, SNB, SB Jar Optimisation (M.O. Shelled Blended) Bentonite 50 NTU Jar Optimisation (M.O. Shelled Blended) Bentonite 150 NTU Jar Optimisation (M.O. Shelled Blended) Bentonite 450 NTU Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled 75 Jars CNB, CB, SNB, SB Jar Optimisation (M.O. Deoiled) Bentonite 50 NTU Jar Optimisation (M.O. Deoiled) Bentonite 150 NTU Jar Optimisation (M.O. Deoiled) Bentonite 450 NTU Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled 78 Blended Jars CNB, CB, SNB, SB Jar Optimisation (M.O Shelled Blended) KAOLIN 50 NTU Jar Optimisation (M.O Shelled Blended) KAOLIN 150 NTU 79 xi

13 Jar Optimisation (M.O Shelled Blended) KAOLIN 450 NTU Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled 81 Blended Jars CNB, CB, SNB, SB Jar Optimisation (M O Deoiled) Kaolin 50 NTU Jar Optimisation (M O Deoiled) Kaolin 150 NTU Jar Optimisation (M O Deoiled) Kaolin 450 NTU RMVG Optimisation: Turbidity Bentonite Clay (50,150,450NTU) and 85 Extract M.O. Shelled Blended, RMVG 250S -1, 329 S -1, 415S -1, 507S Rapid Mix Velocity Gradient for Bentonite Clay Turbidity (50 NTU) for 86 M.O. Shelled Blended extract Rapid Mix Velocity Gradient for Bentonite Clay Turbidity (150 NTU) for 86 M.O. Shelled Blended extract Rapid Mix Velocity Gradient for Bentonite Clay Turbidity (450 NTU) for 87 M.O. Shelled Blended extract Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled 88 RMVG 250S -1, 329 S -1, 415 S -1, 507 S Rapid Mix Velocity Gradient for Bentonite Clay Turbidity (50 NTU) for 89 M.O. Deoiled extract Rapid Mix Velocity Gradient for Bentonite Clay Turbidity (150 NTU) for 89 M.O. Deoiled extract Rapid Mix Velocity Gradient for Bentonite Clay Turbidity (450 NTU) for 90 M.O. Deoiled extract Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled 91 Blended RMVG 250S -1, 329 S -1, 415 S -1, 507 S Rapid Mix Velocity Gradient for Kaolin Clay Turbidity (50 NTU) for M.O. 92 Shelled Blended extract Rapid Mix Velocity Gradient for Kaolin Clay Turbidity (150 NTU) for 92 M.O. Shelled Blended extract Rapid Mix Velocity Gradient for Kaolin Clay Turbidity (450 NTU) for 92 M.O. Shelled Blended extract Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled 94 RMVG 250S -1, 329 S -1, 415 S -1, 507 S Rapid Mix Velocity Gradient for Kaolin Clay Turbidity (50 NTU) for M.O. 95 Deoiled extract Rapid Mix Velocity Gradient for Kaolin Clay Turbidity (150 NTU) for 95 M.O. Deoiled extract Rapid Mix Velocity Gradient for Kaolin Clay Turbidity (450 NTU) for 95 M.O. Deoiled extract SMVG Optimisation: Turbidity - Bentonite Clay (50,150,450 NTU) and 98 Extract M.O. Shelled Blended SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Slow Mix Velocity Gradient for Bentonite Clay Turbidity (50 NTU) for 99 M.O. Shelled Blended extract Slow Mix Velocity Gradient for Bentonite Clay Turbidity (150 NTU) for 99 M.O. Shelled Blended extract Slow Mix Velocity Gradient for Bentonite Clay Turbidity (450 NTU) for 100 M.O. Shelled Blended extract Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled 101 SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Slow Mix Velocity Gradient for Bentonite Clay Turbidity (50 NTU) for 102 M.O. Deoiled extract Slow Mix Velocity Gradient for Bentonite Clay Turbidity (150 NTU) for M.O. Deoiled extract 102 xii

14 Slow Mix Velocity Gradient for Bentonite Clay Turbidity (450 NTU) for 103 M.O. Deoiled extract Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled 104 Blended SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Slow Mix Velocity Gradient for Kaolin Clay Turbidity (50 NTU) for M.O. 105 Shelled Blended extract Slow Mix Velocity Gradient for Kaolin Clay Turbidity (150 NTU) for M.O. 105 Shelled Blended extract Slow Mix Velocity Gradient for Kaolin Clay Turbidity (450 NTU) for M.O. 105 Shelled Blended extract Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled 107 SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S Slow Mix Velocity Gradient for Kaolin Clay Turbidity (50 NTU) for M.O. 108 Deoiled extract Slow Mix Velocity Gradient for Kaolin Clay Turbidity (150 NTU) for M.O. 108 Deoiled extract Slow Mix Velocity Gradient for Kaolin Clay Turbidity (450 NTU) for M.O. 108 Deoiled extract % removal of turbidity Results of Dose optimisation Settling column results Dia.= 18.5 cm Turbidity NTU Dose - 50 mg/l Settling column results Dia.= 18.5 cm Turbidity- 150 NTU Dose -125 mg/l Settling column results Dia. = 30 cm Turbidity NTU Dose - 50 mg/l Settling column results Dia. = 30 cm Turbidity NTU Dose mg/l Settling column results Dia.= 18.5 cm Turbidity- 450 NTU Dose -100 mg/l Settling column results Dia.= 18.5 cm Turbidity- 450 NTU Dose -200 mg/l Settling column results Dia. = 30 cm Turbidity NTU Dose mg/l Settling column results Dia. = 30 cm Turbidity NTU Dose mg/l Settling Column Results (150 NTU) Settling Column Results (450 NTU) Settling Column Results (1000 NTU) ANOVA table Optimisation of Dose: Kaolin clay turbidity 150 NTU, M.O. Shelled 132 blended extract Summary table Results of ANOVA Results of Tukey s method Optimisation at a Glance by Statistical Analysis and experimentation The critical values for q corresponding to alpha =.05 (top) and alpha=.01 (bottom) 136 xiii

15 List of Figures: Sr. No. Fig. No. Description Page No Interparticle bridging with polymers Paddle showing 0.05 m Diameter Existing water supply system of Pune city Aluminium as (Al) in different areas of Pune city Dose optimisation M.O. Shelled Blended Bentonite Clay 50 NTU M.O. Shelled Blended Bentonite Clay 150 NTU M.O. Shelled Blended Bentonite Clay 450 NTU M.O. Deoiled Bentonite Clay 50 NTU M.O. Deoiled Bentonite Clay 150 NTU M.O. Deoiled Bentonite Clay 450 NTU M.O. Shelled Blended Kaolin Clay 50 NTU M.O. Shelled Blended Kaolin Clay 150 NTU M.O. Shelled Blended Kaolin Clay 450 NTU M.O. Deoiled Kaolin Clay 50 NTU M.O. Deoiled Kaolin Clay 150 NTU M.O. Deoiled Kaolin Clay 450 NTU M.O. Protein Powder 50 NTU M.O. Protein Powder 150 NTU M.O. Protein Powder 450 NTU Jar optimisation M.O. Shelled Blended Bentonite Clay 50 NTU M.O. Shelled Blended Bentonite Clay 150 NTU M.O. Shelled Blended Bentonite Clay 450 NTU M.O. Deoiled Bentonite Clay 50 NTU M.O. Deoiled Bentonite Clay 150 NTU M.O. Deoiled Bentonite Clay 450 NTU M.O. Shelled Blended Kaolin Clay 50 NTU M.O. Shelled Blended Kaolin Clay 150 NTU M.O. Shelled Blended Kaolin Clay 450 NTU M.O. Deoiled Kaolin Clay 50 NTU M.O. Deoiled Kaolin Clay 150 NTU M.O. Deoiled Kaolin Clay 450 NTU RMVG Shelled Blended Bentonite Clay RMVG Deoiled Bentonite Clay RMVG Shelled Blended Kaolin Clay RMVG Deoiled Kaolin Clay SMVG Shelled Blended Bentonite Clay SMVG Deoiled Bentonite Clay SMVG Shelled Blended Kaolin Clay SMVG Deoiled Kaolin Clay Alum Dose vs Residual Turbidity M.O. Dose vs Residual Turbidity Time Vs % Overall Efficiency Turbidity 150 NTU & Dia cm Time Vs % Overall Efficiency Turbidity 150 NTU & Dia. 30 cm Time Vs % Overall Efficiency Turbidity 450 NTU & Dia cm Time Vs % Overall Efficiency Turbidity 450 NTU & Dia. 30 cm Time Vs % Overall Efficiency Turbidity 1000 NTU & Dia cm Time Vs % Overall Efficiency Turbidity 1000 NTU & Dia. 30 cm 125 xiv

16 Abstract The treated drinking water of Pune city was analysed for the presence of residual aluminium. It was observed that the use of Poly Aluminium Chloride (PAC) or alum during treatment, resulted in residual aluminium in drinking water which was within the permissible limits but many times it was above desirable limits of drinking water quality standards. Presence of residual aluminium in drinking water has side effects such as Alzheimer disease, neurological disorders and production of more sludge, which led towards research to identify new coagulant for the treatment of water and not having any side effects on user. Moringa oleifera (Shevga or drum stick) seed has good coagulation property and also has been reported to be without constraints of alum. The Moringa oleifera (M.O.) tree dried seeds were collected and analysed to understand the presence of carbohydrates, fats and proteins. It was observed that the protein (the active coagulant) present in the kernel of the seed was 36.9 %. The fat and carbohydrate content in the seed were % and % respectively. The coagulant protein present in M.O. seed helps in turbidity removal. Extraction and purification of the seed powder was carried out to evaluate performance of various forms of coagulant extract and to assess whether it would be necessary to give adequate treatment to the seeds before their use as coagulant. The purification of crude seed powder (shelled blended) was done to obtain deoiled powder and protein powder. The water extracts of these two forms i.e. shelled blended powder and deoiled powder were used throughout the study. Water extract of protein powder was used to optimize its dose. It was observed that water extracts of protein powder and deoiled powder resulted in less dose requirement than water extract of shelled blended powder. The factors which affect the coagulation flocculation process during water treatment are type and concentration of turbidity, dose of M.O. extracts, container geometry, rapid mixing velocity gradient and slow mixing velocity gradient. The laboratory experiments were conducted by using Kaolin clay and Bentonite clay turbidity samples of 50 NTU, 150 NTU and 450 NTU representing the turbidity of raw water in different seasons of the year. The optimized dose obtained for both clay turbidity water samples were different. It was observed that, the optimized dose for Bentonite clay turbidity water samples was less as compared to Kaolin clay turbidity water samples. The circular baffled (CB), circular non baffled (CNB), square baffled (SB) and square non baffled (SNB) containers were used to evaluate the effect of container geometry on turbidity removal efficiency. It was observed that the efficiency of removal of turbidity increases for the container geometries in the following order: SNB, SB, CNB and CB. xv

17 The circular baffled containers showed the best performance in terms of turbidity removal efficiency. The rapid mixing velocity gradients of 250 S -1, 329 S -1, 415 S -1 and 507 S -1 representing 100 RPM, 120 RPM, 140 RPM and 160 RPM respectively were considered to study the effect of intensity of mixing on turbidity removal efficiency. Similarly experiments were conducted by using slow mixing velocity gradients of 22 S -1, 40 S -1, 65 S -1 and 90 S -1 representing 20 RPM, 30 RPM, 40 RPM and 50 RPM respectively. It was observed that for all coagulant extracts, 329 S -1 (120 RPM) was the optimal rapid mix velocity gradient for 50 and 150 NTU turbidity and 415 S -1 (140 RPM) for 450 NTU turbidity. It was also observed that for all coagulant extracts, 40 S -1 (30 RPM) was the optimal slow mixing velocity gradient for 50 and 150 NTU initial turbidity and 65 S -1 (40 RPM) for 450 NTU initial turbidity. The laboratory scale settling column study was also conducted to understand the settling properties of the alum floc and M.O. floc. It was observed that the settling properties of the alum floc and M.O. floc are nearly identical and have almost similar turbidity removal efficiency. The statistical analysis of the experimental results obtained was performed by using ANOVA, Tukey method and t Test. It was observed that, the results obtained by experimentation were similar to results obtained by statistical analysis. Key words: Moringa oleifera; alum; rapid mixing; slow mixing; velocity gradient; optimisation; settling column; water treatment; container geometry. xvi

18 CHAPTER 1 INTRODUCTION CHAPTER 1 INTRODUCTION 1

19 Chapter 1 Introduction This chapter outlines the information regarding the importance of quality of drinking water, its treatment and problems related to the health. The aim of the thesis and the path to reach it is explained. Indian population as per 2011 census is 121 crore. The figures provided by Census of India 2011 shows that the country represents % of the world population. Rural population of India as per 2011 census is 83.3 crore, which is % of India s total population (Report on Census of India 2011, Registrar General and Census Commissioner, Ministry of Home Affairs, India). In developing countries, water treatment plants are expensive, the ability to pay for services is minimal and skills as well as technology are scarce. A vast Indian population residing in rural areas is dependent on the supply of untreated water, which is the root cause of their ailments. Rural population in India is deprived of organized system of collection, treatment and supply of drinking water. Safe water is vital for improving the health and quality of life and for alleviating poverty. It is now well established that 80% of rural diseases may be attributed to polluted water. Such high incidence of waterborne diseases affects labour force, reduces productivity of industry and agriculture and puts stress on budgetary resources needed for development and to strengthen the economy. Invariably people who are suffering because of not having safe water facility also do not have adequate information on how to minimize ill effects of unsafe water. Unsafe water lowers productive potential of the people who can least affords it. Below poverty line women and children for whom quality of water being received / available is susceptible, are more likely to get suffer from it. Despite the rigorous efforts by the Central and State governments during the last 60 years of independence, the goal of safe and adequate drinking water supply to the consumers, both in rural and urban areas, could not be achieved due to several reasons. In rural areas, even after implementation of several Central and State Government schemes and investment of billions for solving the drinking water problem, a larger part of rural population is drinking water from contaminated and polluted sources without any purification treatment. Drinking water treatment involves a number of unit operations and CHAPTER 1 INTRODUCTION 2

20 processes depending on the quality of the water source, affordability and existing guidelines or standards. In conventional water purification, chemicals are necessary for coagulation and disinfection. These two processes are critical unit processes determining success or failure of water purification. The cost involved in achieving the desired levels of treatment depends, among other things, on the cost and availability of chemicals. Commonly used chemicals in water treatment are expensive. Many of the chemicals are also associated with human health and environmental problems (Craper, 1973) and a number of them have been regulated for use in water treatment systems (IS 10500: 1991). After implementation of water supply scheme in rural areas, there is improper maintenance of scheme, inadequate supply of chemicals, unskilled person for addition of chemicals, inadequate funding for maintenance. Due to all these reasons, rural population is dependent on unsafe water sources. It is vital that with increased emphasis on augmenting the source of drinking water, efforts should also be made for ensuring its quality. An increasing awareness among the rural population is being felt but the poor fellows feel helpless in combating this problem at unit and community level. In order to alleviate the prevailing difficulties, approaches should focus on sustainable water treatment systems that are low cost, robust and require minimal maintenance and operation skills. India is one of the countries where the water crisis seems to be imminent; with % of the world s population, India has only 2.45 % of the world s fresh water resource. Recovery of operation and maintenance costs of water systems through water tariff is notoriously low in most states. Unsafe hygiene practices and unsafe disposal of human excreta present the most serious threat to human health. Estimated 17 percentage (Altekar, 2004) of child deaths in India are attributed to diarrhea. This is equivalent to 3,70,600 deaths of children in India every year. Coagulation flocculation process plays one of the important roles in water treatment. Cost and availability of chemicals (coagulants) are important parameters in achieving desired level of water treatment. One of the common coagulant which is widely used in water treatment is alum (Litherland, 1995). The main problems associated with use of alum in water treatment are its low availability and high cost (Litherland, 1995), Alzheimer s disease, production of large sludge volumes (Crapper et al 1973; Miller et al., 1984). There is also a problem of reaction of alum with CHAPTER 1 INTRODUCTION 3

21 natural alkalinity present in the water leading to a reduction of ph, and low efficiency in coagulation of cold waters. As mentioned by Ndabigengesere, Narasiah and Talbolt (1995) many developing countries can hardly afford the high costs of imported chemicals for water treatment. Mankind is grateful to nature for providing many natural coagulants and disinfectants like herbs. It is left to our curiosity and attempt to discover the contribution of nature in our endeavor to tackle water purification in a natural manner. In rural context, the availability of material used in the purification and its acceptability, as environmentally safe, has to be ensured. Locally available material can be exploited for achieving sustainable safe potable water supply to consumers. Natural material can significantly reduce treatment cost if available locally. A number of effective coagulants have been identified from plant origin. Some of the common ones include Moringa oleifera (Jahn, 1988), Nirmali (Tripathi et al, 1976), okra (Al-Samawi and Shokrala, 1996), tannin from valonia (Ozacar and Sengil, 2000), apricot, peach kernel, beans, maize and rice (Bhole, 1987). By using natural coagulants, considerable savings in chemical cost may be achieved. Natural coagulants of vegetable and mineral origin were used in water and wastewater treatment before the advent of synthetic chemicals like alluminium and ferric salts, but they have not been able to compete effectively because of the fact that a scientific understanding of their effectiveness and mechanism of action was lacking. Thus, use of natural coagulants has been discouraged without any scientific evaluation. They have succumbed progressively under modernization and survived only in remote areas of some developing countries (Jahn, 1988). Recently there has been resurgence of interest in natural coagulants for water treatment in developing countries. Moringa oleifera (M. O.) has been one of the most widely used natural coagulants in many developing countries (Litherland, 1995). Studies have reported that M. O. has good coagulation property (Jahn, 1988; Olsen, 1987; Muyibi and Evison 1995; Nkhata 2001). Also, M. O. has been reported to be without constraints of alum. Sludge produced with M. O. is reported to be four to five times compact than that produced with alum (Muyibi et.al., 1995). Turbidity Removal of 95% or more can be achieved with M. O. CHAPTER 1 INTRODUCTION 4

22 It has been reported that use of crude M. O. extract for water treatment increases the organic, nitrate and phosphate contents of water, whereas no such contents are observed if purified M. O. is used (Ndabigengesere and Narasiah, 1998; Okuda et al. 2001). These render crude M. O. extract difficult to use in large treatment systems since presence of organic matter would complicate the treatment process and adversely affect the water quality. To overcome the shortcomings, the crude M. O. extract should be purified by extracting oil and carbohydrates from it. Except in traditional use and in few laboratories or in pilot studies, use of M.O. on large scale in water treatment has not been reported so far. This rejection may be explained by the presentation of M. O. as a low technology appropriate only to developing countries (Jahn 1988). One way to improve acceptance of M. O. as a coagulant all over the world is to show clearly its advantages over conventional coagulants and apply modern technology to supply it to water treatment industry at cheaper cost. M. O. deoiled water extract (98 %) is found to be more effective than M.O. shelled blended water extract (96.6 %) as a primary coagulant (Muyibi et al 2002). Non shelled (seed cover not removed), Shelled (seed cover removed) and also purified protein extract was studied with kaolin suspension. Sludge volume produced was much smaller than alum. In the studies conducted by Ndabigengesere and Narasiah (1998) it was observed that turbidity removal efficiency was improved after suitable purification of crude M. O. extract. A review of texts (Water Treatment Plant Design, 1969) reveals only general design guidelines which suggest that the principle parameters of rapid mixing are intensity of agitation and duration of mixing. The intensity of agitation is generally expressed in terms of power input or the velocity gradient (G). For laminar flow it is the rate of change of velocity with respect to distance in the direction perpendicular to the flow velocity and is generally expressed as mps/s or sec - 1 (IS ). It has been conclusively established that the physical parameters of rapid mix such as velocity gradient, duration of mixing and the container geometry have great influence on the flocculation process and that their optimum combination is dependent on the turbidity of suspension (Mhaisalkar et al 1991). The significance of the velocity gradient (G) for coagulation-flocculation processes is not univocal. Klute and Hahn (1974) found that the local energy dissipation of the stirrer plays an important role in the kinetics of flocculation and in the removal efficiency of suspended solids. According to CHAPTER 1 INTRODUCTION 5

23 Letterman et al (1973) improvement in turbidity removal can be obtained by varying factors like rapid mix rpm, rapid mix time and concentration of coagulant. Further improvements depend on the type of impeller and vessel used. Experiments were carried out by Letterman in order to investigate the influence of different G values and different jar configurations. In all the investigations carried out so far parameters used in conventional jar test have been used to evaluate the coagulation efficiency of M. O. in the treatment of surface waters and synthetic waters. In all such studies the physical parameters such as slow mixing velocity gradient and time, rapid mixing velocity gradient and time were fixed according to standard jar test values for alum coagulation. The only parameter varied in most of the cases was dose of M. O. Furthermore, studies into the interaction between physical parameters affecting coagulation, like slow mix; rapid mix rates & times are not documented. Also the work related to the optimisation of physical parameters of coagulation flocculation process, like different types and concentrations of raw water turbidity, container geometry with M. O. is not documented in the literature. Muyibi (1995) worked on optimisation of M.O. shelled blended and M.O. deoiled extract by using only one type of turbidity. Objective of the present study is to carry out the optimisation studies with natural coagulant i.e. M. O. Initially dose optimisation is carried out for M.O. Shelled blended water extract, M.O. Deoiled extract and purified protein water extract by using Bentonite and Kaolin clay (50, NTU, 150 NTU, 450 NTU) turbidity. In the next stage the circular (baffled and non baffled) and square (baffled and non baffled) containers / jars are used for optmisation of container geometry (Jar Configuration). Different rapid mixing RPM (velocity gradient) are tried in the optimisation of Rapid Mixing Velocity Gradient (RMVG). Lastly the optimisation of Slow Mixing Velocity Gradient (SMVG) is done by varying the slow mixing rpm. Also attempt has been made to investigate the residual alluminium concentrations from drinking water of Pune city. A study was performed to understand the settling characteristics of the floc formed during the use of M. O. and alum coagulant. The specific objectives of the investigation were: Characterisation and purification of the M. Oleifera seed powder. CHAPTER 1 INTRODUCTION 6

24 To study the effect of various forms of coagulant i. e. shelled blended, deoiled and coagulant protein on turbidity removal efficiency. To study the effect of, types of turbidity, concentration of turbidity, container geometry, rapid mixing velocity gradient and slow mixing velocity gradient, on turbidity removal efficiency. To determine the residual alluminium concentration in different drinking water samples collected from Pune city. To study the settling characteristics of the floc formed due to M. Oleifera and alum coagulant. Thesis structure Literature Review: This chapter provides the background information about the topic selected for the study. It gives the idea of national and international status of research work in the context of the research topic selected for the study. Aim and Objective: This chapter describes the aim and different objectives identified for the research work. Methodology: The characterization of the seeds, preparations of stock solutions, fabrication of jars, different procedures for experimentation and stages of research work is explained in this chapter. Residual Alluminium concentration: The residual Alluminium concentration of the samples collected from the different zones of Pune city are presented and discussed in this chapter. Results: The results of the optimisation studies of coagulant dose, container geometry, rapid mixing velocity gradient and slow mixing velocity gradient are explained and discussed in this chapter. Settling Column studies: This chapter describes methodology, experimentation work and the results of the settling column studies. Statistical Analysis: This chapter describes the statistical analysis of experimental results. Conclusion, future work: In this final chapter, major contributions of the thesis are put forth and the problems encountered are considered and further possible developments are explored and possibility of future work is discussed. CHAPTER 1 INTRODUCTION 7

25 CHAPTER 2 LITERATURE REVIEW CHAPTER 2 LITERATURE REVIEW 8

26 Chapter 2 Literature Review In this chapter the process of coagulation and flocculation is explained. Different coagulants and their drawbacks are discussed in detail. The composition of Moringa oleifera and its use in water treatment and methodologies adopted by earlier research workers in this context are explained here. 2.1 INTRODUCTION Finely dispersed suspended and colloidal particles imparting turbidity and colour to raw water cannot be removed sufficiently by the ordinary sedimentation process. Adding a coagulant and mixing and stirring the water causes the formation of settleable particles. These flocs are large enough to settle rapidly under the influence of gravity, and may be removed from suspension by settling and filtration. The choice and dose rates of coagulants will depend on the characteristics of the water to be treated and must be determined from laboratory experiments. The chemicals must be readily available and their application must be closely monitored. Chemical Coagulation-flocculation followed by sedimentation, is a very common treatment method used mainly in water treatment practices. Chemical coagulants work efficiently in a narrow ph range; they reduce alkalinity of water. The residual alum in water leads to Alzheimer diseases. There is also problem of reaction of alum with natural alkalinity present in the water leading to a reduction of ph and low efficiency in coagulation in cold water. Recently more interest has been aroused, especially in developing countries, in possible application of natural coagulants. Suspended and colloidal matter such as clay, silt, finely divided organic and inorganic matter, and plankton and other microscopic organisms are responsible for turbid waters. At the same time, on the household level, coagulation by means of natural coagulants of plant and soil origin and simple devices has been practiced traditionally by many people in developing countries (Jahn 1988). CHAPTER 2 LITERATURE REVIEW 9

27 Table No. 2.1: Major impurities of natural water (Montgomery 1985) Ionic and dissolved Nonionic and suspended Gaseous Cationic Anionic Calcium Magnesium Sodium Potassium Ammonium Iron Manganese Arsenic Bicarbonate Carbonate Hydroxide Sulfate Chloride Nitrate Phosphate Fluoride Silica Organic matter Colour Turbidity Silt, mud Other suspended matter Colour Organic matter Colloidal silica Microorganism Plankton, bacteria Oil corrosion products CO 2 H 2 S NH 3 O 2 Chlorine Process Description:- Clarification can be described in four distinct steps. (a) Coagulation -Neutralization of the charges on suspended Particles to overcome the repulsion between particles and promote their aggregation. (b) Flocculation -Formation of interparticle bridges leading to macroscopic floc. (c) Sedimentation -Floc settling process. (d) Filtration -Passing the water through granular media (such as sand garnet, Anthracite) to remove any remaining suspended solids. 2.2 COAGULATION AND FLOCCULATION: Turbidity in water is due to suspended matter such as clay, silt, organic material and microscopic organisms. Turbidity is measured by the amount of incident light scattered by particles in the water sample. Control of turbidity in drinking water is important for both aesthetic and health reasons. Excessive turbidity detracts from the appearance of water and is often associated with unpleasant tastes and odour. Turbidity is also linked to increased bacteria and other pathogens in treated water. Turbidity is undesirable for three reasons: 1. Aesthetic considerations CHAPTER 2 LITERATURE REVIEW 10

28 2. Solids may contain heavy metals, pathogens or other contaminants. 3. Turbidity decreases the effectiveness of water treatment techniques by shielding pathogens from chemical or thermal damage, or in the case of UV treatment, absorbing the UV light itself. As per Central Public Health and Environmental Engineering Organization (CPHEEO, 1999), an acceptable water quality standard for turbidity is 2.5 NTU and cause for rejection is 10 NTU. As per this, inlet turbidity for slow sand filter should be less than 20 NTU. As per IS (1991), required desirable limit is 5 NTU and permissible limit in the absence of alternate source is 10 NTU. Drinking water quality standards as per WHO guide lines (2000), turbidity level likely to give rise to consumer complaints is 5 NTU (Altekar 2004) Mechanism of Coagulation: Most suspended particles present in water are negatively charged, electrostatic in nature, degree of charge depends upon type of solid and electrolytic environment. When a colloidal particle is dispersed in water it can ionize, absorb and attract low molecular weight ions to its surface. Several decades of study on mechanism of coagulation have led to numerous theories, but most of them agree that both chemical and physical actions are involved in coagulation. The stability of the colloid depends upon forces of attraction that cause colloids to aggregate and upon repulsion forces who act to disperse the particles (Werner, 1968). Factors that destabilize colloids are gravitational forces, Van der Waal forces and Brownian movement. The small mass of colloidal systems limits the effect of gravitational forces. Van der Waal forces of attraction between particles are envisaged as molecular cohesive forces. They are caused by interaction of the particle dipoles and are either permanent or induced. Colloidal particles generally carry a negative electrical charge. Their diameter may range from 10-4 to 10-6 mm. They are surrounded by an electrical double layer (due to attachment of positively charged ions from the ambient solution) and thus inhibit the close approach to each other. They remain finely divided and do not agglomerate. Due to their low specific gravity, they do not settle out. CHAPTER 2 LITERATURE REVIEW 11

29 A coagulant (generally positively charged) causes compression of the double layer and thus the neutralization of the electrostatic surface potential of the particles. The resulting destabilized particles stick sufficiently together when contact is made. Rapid mixing (a few seconds) is important at this stage to obtain uniform dispersion of the chemical and to increase the opportunity for particle-to-particle contact. Subsequent gentle and prolonged (several minutes) mixing cements the still microscopic coagulated particles into larger flocs. These flocs then are able to aggregate with suspended matter. When increased sufficiently in size and weight, the particles settle to the bottom. Destabilization of colloidal dispersions: The effective removal of the colloidal and suspended particulates from water depends on a reduction in particulate stability. Particle destabilization can be achieved by four mechanisms (Dentel 1988): 1. Double layer compression 2. Adsorption and charge neutralization 3. Enmeshment in a precipitate and 4. Adsorption and interparticle bridging a) Double Layer Compression: - A high ionic concentration compresses the layers composed predominantly of counter ions toward the surface of the colloid. If this layer is sufficiently compressed then the Van der Waal force will lead to interparticle attraction and no energy barriers will exist. An example of ionic layer compression occurs in nature when a turbid stream flows into the ocean where the ion content of the water increases drastically and coagulation and settling occur. Although coagulants such as aluminium and ferric salts used in water treatment ionize at the concentration commonly used they would not increase the ionic concentration sufficiently to affect ion layer compression. b) Adsorption and Charge Neutralization: - The nature rather than the quantity of the ions is of prime importance in the theory of adsorption and charge neutralization. Although Aluminium sulphate is used as in the example below ferric chloride behaves similarly. The ionization of aluminium sulphate in water produces sulphate anions (SO 4 ) 2 and aluminium cations (Al 3 ). The sulphate ions may remain in this form or combine with a variety of aquametallic ions and hydrogen. CHAPTER 2 LITERATURE REVIEW 12

30 Al 3+ + H 2 O AlOH 2+ + H +... (1) Al H 2 O Al(OH 2 ) + + 2H +... (2) 7Al H 2 O 4+ Al 7 (OH) H + (3).. Al H 2 O Al(OH) 3 + 3H +... (n) The aquametallic ions thus formed become part of the ionic cloud surrounding the colloid and because they have a great affinity for surfaces are adsorbed onto the surface of the colloid where they neutralize the surface charge. Once the surface charge has been neutralized the ionic cloud dissipates and the electrostatic potential disappears so that contact occurs freely. Overdosing with coagulants can result in destabilizing the suspension. If enough aquometallic ions are formed and adsorbed the charges on the particles become reversed and the ionic clouds reform with negative ions being the counter ions. c) Enmeshment in a precipitate: - The last product formed in the hydrolysis of alum is aluminium hydroxide, Al(OH) 3. The Al(OH) 3 forms in amorphous gelatinous flocs that are heavier than water and settle by gravity. Colloids may become entrapped in a floc as it is formed or they may become enmeshed by its sticky nature as the flocs settle. d) Adsorption and Interparticle Bridging: - Large molecules may be formed when aluminium or ferric salts dissociate in water. Equation n above is an example although larger ones are probably formed also. Synthetic polymers also may be used instead of or in addition to metallic salts. These polymers may be linear or branched and are highly surface reactive. Thus several colloids may become attached to one polymer and several of the polymer colloid groups may become enmeshed resulting in a settleable mass. In addition to the adsorption forces, charges on the polymer may assist in the coagulation process. Metallic polymers formed by the addition of aluminium or ferric salts are positively charged while synthetic polymers may carry positive or negative charges or may be neutral. Judicious choices of appropriate charges may do much to enhance the effectiveness of coagulation. CHAPTER 2 LITERATURE REVIEW 13

31 Fig. No.2.1 Interparticle bridging with polymers (Peavy et al 1984) Kinetics of particulate aggregation: Initially, the distribution of particulates consists of primary particles not yet stabilized. Upon addition of an inorganic or a organic coagulant, the particulates are rapidly destabilized. This leads to the formation of unstable microflocs ranging from 1 to about 100 μm. Further aggregation and growth of the flocs occurs due to particulate collisions caused by transport. During the transport process the flocs are subjected to unequal shearing forces. This leads to erosion and disruption of some of the floc aggregates or floc break up. Finally, after some period of mixing, a steady state floc size distribution is reached, and the growth and disruption of the floc particles is roughly equal. The rate, at which the steady state size distribution is achieved, as well as the form of the size distribution, will depend on the hydrodynamics of the system and the chemistry of the coagulant-particulate interactions. (Montgomery 1985). CHAPTER 2 LITERATURE REVIEW 14

32 2.3 COAGULANTS: Chemicals It is common practice to use aluminium and iron salts. Both salts hydrolyze when added to water. They form insoluble material -aluminium and ferric hydroxides -when reacting with calcium and magnesium carbonates, which are almost always present in water (alkalinity and hardness of the water). If those carbonates are not present in sufficient concentration (soft water) hydrated lime Ca(OH) 2 or sodium carbonate Na 2 CO 3 may also be added. In the case of aluminium sulphate, this reaction can be represented as follows: Al 2 (SO 4 ) Ca(HCO 3 ) 2 = 2 Al(OH) CaSO CO 2 The formation of the insoluble hydroxides depends on the ph. It has been shown that aluminium sulphate coagulates best in a ph range between 6.5 and Coagulants of Plant Origin In India, ancient writings refer to the use of the seeds of the Nirmali tree, Strychnos potatorum as a clarifier. Tunaflex and Nirmali seeds have been successfully employed in municipal treatment plants in combination with alum. Sanskrit writing from India reported that the seeds of the Nirmali tree were used to clarify turbid surface water over 4000 years ago and in the last century Sudanese women discovered clarifying properties in the Moringa trees. The sludge produced with Moringa coagulation has a much smaller sludge volume than conventionally produced sludge, and the sludge consists of organic solids free of heavy metals, assuming heavy metals are not present in the raw water. It has potential to be very cost effective. Sludge produced with M. oleifera is reported to be four to five times compact than that produced with alum (Muyibi et al, 1995). Turbidity Removal of 95% or more can be achieved with Moringa oleifera. The use of M. oleifera as a coagulant is mostly used in water treatment that too on a small scale and major work has been reported in laboratory scale water treatment studies. Natural Coagulant vs. Inorganic Coagulant:- Many developing countries can hardly afford the high costs of coagulants and coagulant aids for water and waste water treatment (Ndabigengesere, 1995). Also recent studies have pointed out several serious drawbacks of using aluminium salts, such as: CHAPTER 2 LITERATURE REVIEW 15

33 Drawbacks of Alum: 1) Alzhemeier disease and similar health related problems associated with residual aluminium in treated water. 2) It produces large sludge volumes. 3) It may require ph and alkalinity adjustment if the raw water has low alkalinity. 4) Low efficiency in coagulation of cold water. 5) It is costly. Advantage of Moringa Oleifera Coagulant over Alum: 1. It is natural and completely non toxic. 2. It has a high coagulation activity for high turbidity water. 3. No ph and alkalinity adjustments are required. 4. Besides reduction of turbidity it reduces the level of microorganisms in water. 5. It is completely biodegradable and hence easy to dispose off. 6. The volume of sludge produced is considerably less in case of Moringa than in case of alum. Disadvantages of M. Oleifera: 1. It may be disadvantageous to use M. Oleifera as it increases the orthophosphates content in treated water. 2. The costs of the purified active protein will probably be higher than the cost of alum at present. 3. At present availability of seeds is a problem. It requires mass cultivation. 4. The treated water from M. Oleifera gives odour after two days of storage. 5. It increases dissolved organic carbon in treated water. 2.4 M. OLEIFERA M. oleifera, simply known as Moringa, is native to north India but is now found throughout the tropics. It belongs to the family Moringaceae having 14 species. Moringa is also known as horseradish tree, drumstick tree and mother s best friend. The fruit ripens from April to June and the pods are triangular in cross section, 30 to 50 cm long and contain oily, black, winged seeds. CHAPTER 2 LITERATURE REVIEW 16

34 Photo No. 2.1 Tree M. oleifera Photo No. 2.2Seed of MO Photo No. 2.3 Pods of MO General Composition of M. Oleifera Organic matter consists of the six principal elements namely Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), Phosphorus (P), and Sulphur (S). The principal groups of the above constituents are proteins, Carbohydrates, Lipids; Lignin and free Amino Acids (Okuda 2001). Anhwange et al (2004) study reports the nutritional, anti-nutritional and some chemical studies of the seeds of M. oleifera (See Table No. 2.2). Table No.2.2: Nutritional and anti-nutritional composition of M. oleifera seeds Content M. oleifera Oil (%) Protein (%) Carbohydrate (%) 9.11 Crude fibre (%) 3.28 Phytate (%) Tannins (%) Coagulation mechanism of M. Oleifera seeds: The coagulation mechanism of the M. O. seed powder has been attributed to the adsorption and charge neutralization (Ndabigengesere et al, 1995; Gassenschmidt et al 1995), interparticle bridging (Muyibi et al 1995) and enmeshment by netlike structure (Muyibi et al 1995). The compounds accomplishing coagulation in water are low cationic peptides with molecular weight ranging in molecular mass of 6-16 KDa with an isoelectric point value of around 10 and high molecular mass protein component with CHAPTER 2 LITERATURE REVIEW 17

35 molecular weight of 66 KDa (Okuda et al 2001). The small sized proteins of low molecular weight accomplish coagulation by adsorption and charge neutralization while flocculation by interparticle bridging is mainly characteristic of high molecular weight polyelectrolyte (Gassenschmidt et al, 1995; Ghebremichael, 2004). Water Treatment Plant design (1969) suggests a contact time in the range of seconds for velocity gradient of s -1. Water Quality and Treatment (1971) state that no clear cut guidelines exist for determining the power dissipation or detention time required to disperse chemicals in a flow of water. IS 7090 (1985) recommends velocity gradient in the range of s -1 and a detention time of 20 to 60 seconds. Manual on Water supply and Treatment (1999) also recommends the value of velocity gradient in the range of s -1 and a detention time of 20 to 60 seconds irrespective of water quality. Hudson (1965) stated that the floc formed following rapid mixing contain approximately 2.5 times more solids than that formed in the absence of rapid mixing. Letterman (1973) reported that different container geometries result in turbulent eddies of different intensities and frequencies. The best container combination transfers energy to the water in the form of high frequency eddies and is effective for developing flocs that have high apparent initial flocculation rate. This results in more effective turbidity removal, i.e. low residual turbidity. Klute and Hahn (1974) found that the local energy dissipation of the stirrer plays an important role in the kinetics of flocculation and in the removal efficiency of suspended solids. The study performed by Leentvar (1980) reported that the increase in G value caused decline in the flocculation effect, although a G value of about 25 s -1 showed an optimal coagulation flocculation result for all impeller types. The best results were obtained in coagulation flocculation experiments in the square tanks. He also reported that coagulation flocculation performance at a typical G value differs slightly with the stirrer type and type of vessel used. CHAPTER 2 LITERATURE REVIEW 18

36 Bhole et al (1983) compared potato, masur, singhara, M. oleifera (shevga), jawar and nirmali as natural coagulants. They reported that all materials are edible so there is no question of toxicity. Potato is less efficient than other coagulants. All other coagulants have more or less same efficiency although their performance is slightly inferior to that of alum. Performance of masur, jawar and nirmali as coagulant aids is remarkable while that of potato and shevga is not so. Increase in dose of coagulant aid does not improve the performance in that proportion. Higher dose of coagulants also does not substantially improve the performance. Effect of ph value of shevga, jawar and nirmali is best around ph 7. Addition of coagulant aid first followed by alum gives best performance in case of potato, masur and shingara. While addition of alum first followed by coagulant aid results in best performance of jawar and nirmali seeds. Ghosh et al (1985) suggested an optimum rapid mix velocity gradient of 800 s -1 for 25 NTU turbidity. They conducted experiments for a fixed rapid mix time of 120 seconds. It is quite possible that some other combination of rapid mix velocity gradient and time may produce still better results. Mhaisalkar et al (1986) developed simple electrical method to measure the power input by an impeller to the system based on which the velocity gradient can be determined. It has been shown that for a given impeller speed, the energy input increases depending upon the impeller container geometries in the following order cylindrical without baffles, square without baffles, cylindrical with baffles and square with baffles. The results obtained with the new method compare very well with those obtained by other workers and the method can provide a valuable tool for mechanical mixing devices for coagulation-flocculation in water treatment. Bhole (1987) compared hirda, beheda and amla as coagulant and coagulant aid. This study indicated that hirda, beheda and amla had good coagulation effects when used as primary coagulants or coagulant aid. Effect of sequence of addition of alum as coagulant and hirda, beheda and amla as coagulant aid were also studied. He reported optimum ph range of 7 to 7.5. He reported that addition of coagulant aid followed by alum gave better performance in case of beheda and amla while simultaneous addition proved better for hirda. The question of toxicity does not arise since all the three are edible materials. CHAPTER 2 LITERATURE REVIEW 19

37 Bhole et al (1990) carried experimentation on natural coagulants of all types. They tested nirmali seeds, masur, jawar, potato, singhara, hirda, beheda, amla, guar, red seed, starch, sorella seeds, methi powder, tur, udad, etc. They tried these natural coagulants alone as well as in conjunction with alum. They found Nirmali and Jawar when used alone, can remove the turbidity up to 84%. Whereas, in case of hirda, beheda and amla turbidity removal was 50%, 60% and 35% respectively. But for higher turbidity removal all three behaved more or less identically. They also concluded that beheda and amla were remarkable in performance with low initial turbidity. They also concluded that all above were less effective than alum, but possess coagulation property. In the study performed by Jahn (1988), Moringa seeds have been observed to act as primary coagulant and have been recommended for domestic water treatment in rural areas of Africa and Asia, where people cannot afford conventional coagulants. It described the process of identifying potential natural flocculants and of managing crops as well as methods of optimizing simplified water coagulation with plant materials. The study on optimizing physical parameters of rapid mix design or coagulationflocculation of turbid waters was carried out by Mhaisalkar et al (1991). In this study the experiments were designed using the single factor method of optimization. It conclusively established that the physical parameters of rapid mix such as velocity gradient, duration of mixing and the container geometry have a great influence on the flocculation process and that their optimum combination is dependent on the turbidity of suspension. The product of velocity gradient and time (GT) is a parameter of only limited significance in the design of rapid mix. The results showed that a square shaped unit with baffles gives the best performance compared to the other geometries. Folkard G.K et al (1994) project has investigated the use of crushed seeds from the tree M. oleifera as a Natural alternative to the conventional chemicals. The seeds reduce the turbidity of the raw water by 80% leaving clear, very low turbidity water. Dosing levels of MO seed varied between mg/l depending on initial raw turbidity. The result of dosing MO seed solution at 75 mg/l over a seven hour period compares favourably with performance figures for alum dosing at 50 mg/l. M. oleifera seeds contain 40% by weight of oil, with the remaining press cake containing the active ingredients for natural coagulation. CHAPTER 2 LITERATURE REVIEW 20

38 Sutherland et al (1994) reported that crushed seeds of the tree shevga or M. oleifera are a viable replacement coagulant for proprietary chemicals in developing countries. The seed pods of M. oleifera Lam are allowed to dry naturally on the tree prior to harvesting. The seeds are easily shelled, crushed and sieved using traditional techniques employed for the production of maize flour. Dosing solutions are generally prepared as 1 to 3% concentration solutions. The crushed seed powder, when mixed with water, yields water soluble proteins which possess a net positive charge. The solution acts as a natural cationic polyelectrolyte during water treatment. M. oleifera seeds contain 40% by weight of oil and laboratory work at Leicester confirmed that the press cake remaining after oil extraction still contains the active coagulant. The seed kernels contain significant quantities of a series of low molecular weight, water soluble proteins which, in solution carry an overall positive charge. The proteins are considered to act similarly to synthetic, positively charged polymer coagulants. When added to raw water the proteins bind to the predominantly negatively charged particulates that make raw water turbid. Under proper agitation these bound particulates then grow in size to form the flocs, which may be left to settle by gravity or be removed by filtration. Two further advantages of seed treatment are that the effectiveness is, in general, independent of raw water ph and the treatment does not affect the ph of treated water. Studies have been carried out to determine the potential risks associated with use of the seeds in water treatment. To date all the studies have concluded that there is no evidence to suggest any acute or chronic effects on humans, particularly at the low doses required for water treatment. The main objective of the study by Ndabigengesre Anselme et al (1995) was to purify and characterize the active components in order to investigate their mechanism of coagulation and to compare Moringa as a coagulant with alum. From the observations it was observed that when treating highly turbid waters, it is not necessary to separate the shell from the seed. The study showed that the active agents in aqueous Moringa extracts are dimeric cationic proteins, having molecular weight of 13 KDa and isoelectric point ranging in between Adsorption and neutralization of the colloidal charges appear in the mechanism of coagulation with M. oleifera. As it was compared to alum, the optimal dosage of shelled M.O. seeds was nearly the same (50 mg/l) but as far as Nonshelled were concerned; the dosage is greater (500 mg/l) for low initial turbidity water. CHAPTER 2 LITERATURE REVIEW 21

39 The study also showed that the purified protein is more effective coagulant than alum. Only water was able to extract the active agents in the coagulation with Moringa. The volume of sludge produced was considerably less in case of Moringa than in case of alum. Ghebremichael et al (1995) paper discussed about the water and salt extraction of a coagulant protein from the M.O. seeds. It also included purification using ion exchange, its chemical characteristics, and coagulation and anti microbial properties. M.O. coagulant protein was purified. During the mass spectrometric analysis of the purified water extract it suggests that it contained at least four homologous proteins. The protein has a capability of thermo resistance and remained active after 5 hrs heat treatment at 95 0 C. The M.O. extract showed similar coagulation activity as that of alum, with samples of high turbidity. The study also presented the easy methods for both testing of M.O. coagulating proteins and the purification of protein. Muyibi et al (1995) present results of optimisation studies on physical factors including rapid mix velocity gradient & time, slow mix velocity gradient & time and the dosage of M.O. for low, medium and high raw water turbidities ( NTU). Increasing dosages ultimately leads to charge reversal and subsequent restabilization of destabilized particles. Within the dosage range of 50 and 300 mg/l, there was an optimum dosage at 50 and 100 mg/l respectively for initial turbidity of NTU and NTU. At initial turbidity of 50 NTU (low turbidity) the rapid mix velocity gradient and time was 432 sec -1 and 1 min respectively. At initial turbidity of NTU (moderate to high turbidity) the optimum rapid mix velocity gradient and time was 443 sec -1 and 4 min. respectively. Similarly the optimum slow mixing velocity gradient and time recorded were sec -1 and 20 min. for low turbidity water; and sec -1 and 25 min. for medium and high turbidity water. Muyibi. and Okuofu (1995) performed the experiments by using M.O. seeds through different ways (by using as primary coagulant, by using as conjunctive use with alum, and by using as coagulant Aid). M.O. seed extract is a polyelectrolyte with molecular weight ranging from 6000 to Daltons. Removal of turbidity was found to increase with increase in the initial turbidity of the raw water. As far as the conjunctive use is concerned, it was observed that flocs formed were bigger, denser and settled faster after CHAPTER 2 LITERATURE REVIEW 22

40 slow mixing, than when alum or M. oleifera alone were used. M. oleifera seed suspension as a coagulant aid showed that the optimum dose of alum without M. oleifera was 40 mg/l. Turbidity removal of 50 % was achieved by using M.O. as a primary coagulant. The rates of formation of flocs were the same or often faster than with alum alone. When used with M.O. in combination with alum during this study, between 40% and 80% saving in alum was observed. Muyibi and Evison (1996) investigated the effects of 5 process variables on softening hard water and coagulation of surface water with M. oleifera seed extract. The application of increasing dosage of M.O. from 100 to 450 mg/l gave a turbidity removal between 36 to 98.2 %. The combination of 30 mg/l alum + 40 mg/l of M. O. gave the lowest residual turbidity for the raw water sample. It corresponds to 40 % saving in alum usage. The experiments performed by Ndabigengesere and Narasiah (1998) reveal that the difference in optimum dosage between shelled and non-shelled dry Moringa seeds is because of the active proteins present in the kernel. Results of the coagulation experiments with the purified protein showed that the optimal dosage was mg/l which is 50 to 100 times lower than the optimal dosage of the crude water extract of the shelled dry Moringa oleifera seeds. The kernel contains 35% of oil and 37% of proteins. Compared to alum, M.O. seeds do not need ph and alkalinity adjustments. Okuda et al (1999) demonstrated that protein is the main active component in the seed extract. The initial ph of the suspension was 7.1+_ 0.1. The improvement of coagulation efficiency by NaCl is apparently due to salting in mechanism in proteins wherein salt increases protein dissociation, leading salt ionic strength increases. As the dose of coagulant increased, the residual turbidity decreases. Okuda et al (2001) focused on the coagulation mechanism by the purified coagulation solution (MOC-SC-pc) with the coagulation active component extracted from M.oleifera seeds using salt solution. The objective of this study was to clarify the coagulation mechanism of the MOC-SC-pc. It was found that, the increase in ionic strength by salt caused the increase in solubility of the active components. The coagulation capacity of MOC extracted with 1M NaCl solution (MOC-SC) was 7.4 times higher than that of MOC-DW. Another disadvantage of MOC-DW for water treatment is to increase CHAPTER 2 LITERATURE REVIEW 23

41 dissolved organic carbon (DOC). The purified coagulant (MOC-SC-pc) from MOC-SC did not increase dissolved organic component (DOC) after coagulation. Coagulation mechanism of MOC-DW was reported to be adsorption and neutralization. The coagulation mechanism of MOC-SC-pc may be different from that of MOC-DW because its active components are different. From the study it was concluded that, the coagulation mechanism of MOC-SC-pc seemed to be an enmeshment by the insoluble matter formed by the coagulating active component in MOC-SC-pc. Muyibi et al (2002) investigated the effects of extracting oil from M. oleifera on its coagulation effectiveness using turbid surface water. The ground powder was divided into two portions. One portion had the oil extracted (shelled blended oil extracted) while the other portion (shelled blended) was used to prepare the second stock solution. Moringa oleifera dosages of 50 to 300 mg/l in multiples of 50mg/L added simultaneously to the raw water in the beakers and stirred (rapid mixing) for 4 min. The speed of mixing was then reduced to 20 rpm (for turbidity <100NTU) for 20 min and 40 rpm (for turbidity > 100NTU) for 25 min. The ph varied from 6.2 to 6.7 implying slight acidity with alkalinity varying from 14 to 20 mg/l as CaCO 3. M. oleifera is known to be a short chain cationic polyelectrolyte so turbidity removal will be mainly through electrostatic path mechanism. It may therefore be postulated that the oil content in the seed will form an emulsion or film coating which may inhibit the contact with the surface of reaction and thus reduce floc formation. Shelled oil extracted M. oleifera has been found to be more effective than the shelled blended seeds as primary coagulant for turbid water. Katayon S. et al (2004) studied the effect of storage duration and temperature of Moringa oleifera stock solution on its performance in coagulation. For this study, four types of turbidities were considered namely low turbidity (<50 NTU), medium turbidity ( NTU), high turbidity ( NTU ) and very high ( >300NTU).The result revealed that although the same dosage of M.O. seed extract applied on both type of water samples, the synthetic turbid water showed better performance in terms of turbidity removal. It was concluded that M. oleifera was not an effective coagulant for low turbidity water sample. Also, coagulation with M.O. stock solution, which was kept at CHAPTER 2 LITERATURE REVIEW 24

42 room temperature for duration of up to 3 days, is most effective on medium, high and very high turbidity water. The study was conducted by Das et al (2005) for optimization of coagulation dosage and settling period for the coagulant, both individually as well as in blend. Through this study it was observed that at a settling time of 1hr, M.O. is found to yield the maximum at optimum dosage of 40 mg/l in 300 ml of the synthetic turbid water. The results clearly indicated only marginal improvement in coagulation (< 0.3%) by Moringa oleifera than coagulation by alum. The blend proportion was estimated based on their optimal dose and it was observed that at a proportion of 3:2 (alum: M. oleifera), i.e. 15 mg of alum in 10 mg of M oleifera, the turbidity removal is as good as the alum itself (with a maximum difference of 0.1%) with much improved ph (close to that by alum). The optimal settling time for alum, M. oleifera and their blend (in the optimal blend proportion) was found to be 60 min, because for higher settling time the improvement in coagulation is marginal for all three coagulants studied. Ghebremichael et al (2005) discussed about the water and salt extraction of a coagulant protein from the M.O. seeds. M.O. coagulant protein was purified using a High-trap CM FF 1ml cation exchanger column. The M.O. extract showed similar coagulation activity as that of alum, with samples of high turbidity. The study also showed that the M.O. extract and cecropin- A were found to have similar flocculation effect for clay and microorganism. Liew et al (2006) study reports that, M. O. being a polyelectrolyte removes turbidity by partial charge neutralization, depending on the initial turbidity of the particles. Results of the coagulation studies on low turbidity surface water using M. oleifera showed that its use as a primary coagulation was able to achieve up to 80% turbidity removal. The conjunctive use of both, the alum as primary coagulant and M. oleifera as coagulant aid gave a better turbidity removal as compared to each used individually. The oil extracted M. oleifera and filtration process appeared to be effective in reducing the turbidity more than 97%. They found that the samples with initial turbidity of 451 NTU, shelled-oilextracted M. oleifera was able to achieve 98% turbidity removal at an optimum dosage of 200mg/L compared to 96.9% obtained at optimum dosage of 300 mg/l using the shelledblended variety. For the low turbidity of 56 NTU, shelled-oil-extracted M. oleifera CHAPTER 2 LITERATURE REVIEW 25

43 achieved 87% turbidity removal at 250 mg/l optimum dosage while shelled-blended was able to achieve 81%. The factors affecting the coagulation flocculation process are: type and concentration of turbidity, container geometry, and rapid mixing velocity gradient and slow mixing velocity gradient. The literature review led to very particular aspects of the Coagulation flocculation process with chemical and natural coagulants. Many researchers have worked on these factors using alum as coagulant. Very few researchers have used M. Oleifera as coagulant to study the some of the physical factors affecting coagulation flocculation process. Hence it was decided to use M. Oleifera as coagulant and to perform optimisation studies. The variables used were: type and concentration of turbidity, container geometry, and rapid mixing velocity gradient and slow mixing velocity gradient. CHAPTER 2 LITERATURE REVIEW 26

44 CHAPTER 3 AIM AND OBJECTIVES CHAPTER 3 AIM AND OBJECTIVES 27

45 Chapter 3 Aim and Objectives In this chapter the Aim and Objectives of the study are given. Aim: Optimisation of Coagulation Flocculation Treatment by Moringa Oleifera seed extract: influence of Physical parameters Objectives: 1. To study the quality of drinking water supplied to Pune city with respect to the presence of residual Alluminium. 2. To characterise the Moringa oleifera seed powder. 3. To optimise the coagulant dose, container geometry, rapid mixing velocity gradient and slow mixing velocity gradient 4. To study the settling characteristics of the floc formed due to alum and Moringa oleifera coagulant. 5. The statistical analysis of the experimental results obtained. CHAPTER 3 AIM AND OBJECTIVES 28

46 CHAPTER 4 MATERIALS AND METHODS CHAPTER 4 MATERIALS AND METHODS 29

47 Chapter 4 Materials and Methods In this chapter the different methods and procedures used for analysis and experimentation are explained. The information about the materials used during experimentation and the procedures followed in the optimisation studies are given in this chapter. 4.1 SEEDS COLLECTION AND SAMPLING The M. oleifera seeds from Borno, Yobe and Adamawa states of Nigeria showed similar antibacterial properties but different coagulation properties. The seeds from Adamawa state exhibited the fastest turbidity removal potential (Nwaiwu N.E et al 2012). Hence the tree dried seeds were collected from four districts i.e. Amravati, Pune, Kolhapur, and Sangli of Maharashtra state. The following coning and quartering method was adopted to obtain the representative sample of seeds 1. Average 500 gms of seeds were required for whole study. The seeds were mixed thoroughly by taking 2 Kg of seeds from each district totaling 8 Kg. 2. By coning and quartering method 500 gms of seeds were collected as representative sample. Remaining 7.5 Kg seeds were discarded. 3. Finally 500 gms of seeds remained and these seeds were used for study purpose. 4.2 CHARACTERIZATION OF SEEDS: Small quantity of seeds was sent for characterization purpose. The seeds were analyzed at National Agriculture and Food Analysis and Research Institute, Pune. Table No. 4.1: The methods of seed analysis Parameters Test Method Protein AOAC Fat Ranganna Carbohydrates IS: Crude Fiber SP-18 (P-IX) 1984 Moisture Ranganna Ash AOAC CHAPTER 4 MATERIALS AND METHODS 30

48 4.3 BENTONITE CLAY: The term Bentonite was first applied to a particular, highly colloidal, plastic clay found near Fort Benton in the Cretaceous beds of Wyoming U. S. A.; it has unique characteristic of swelling to several times its original volume when placed in water. It forms thixotropic gel with water, even when the amount of bentonite in such gel is relatively small. It is defined as clays produced by the alteration of volcanic ash in situ. Such clays are largely composed of monotmorillonite clay minerals. They are generally highly colloidal and plastic. It is a natural colloidal hydrated aluminum silicate (clay) found in many parts of world, especially Italy, Canada, South Africa and Mid-West U.S.A. The finest variety of bentonite comes from Fort Benton in U.S.A. and hence named as Bentonite. Bentonite is found in the form of soapy lumps in the mines. Lumps are steam dried, followed by pulverization and sifting. It is a pale buff (yellowish or pinkish tint) coloured cream, a very fine powder, free of grittiness. It is odourless and earthy in taste. Bentonite is insoluble in water and organic solvents. When added to water, it swells about 12 times its volume. It contains about 80.00% monotmorillonite. 4.4 KAOLIN CLAY: The name kaolin is a corruption of the Chinese kauling meaning high ridge, the name of a hill near Jauchau FU, China, where the material was obtained centuries ago. The structure of kaolinite is composed of a single silica tetrahedral sheet and a single alumina octahedral sheet combined in a unit so that the tips of silica tetrahedrons and one of the layers of the octahedral sheet are formed (Grim 1953). Occurrences in many parts of the world are well known today. Kaolin is a purified native hydrated aluminum silicate free from gritty particles. It is obtained by powdering the native kaolin, elutriating and collecting the fraction, which complies with the requirements of particle size. Size of kaolin clay varies between 10 to 60 µm and density of kaolin clay is 2.3. It is insoluble in water and in mineral acids. It is not affected by dilute hydrochloric acid, but decomposed by concentrated sulphuric acid. After prolonged boiling it absorbs small amount of water. The native clay is derived from decomposition of the feldspar or granite rock and contains 47% silica, 40% alumina and 13% water. It is mainly found in south Eastern United States, England, France and India. CHAPTER 4 MATERIALS AND METHODS 31

49 4.5 PREPARATION OF STOCK SOLUTIONS: Preparation of seed powder: The sampled seeds of M. oleifera showing no signs of discoloration and softening were obtained and seed powder was prepared. The seeds were sun dried, the testa and wings were manually removed and the white kernel was ground to fine powder of approximate size 600 micro meter using domestic food blender, to achieve solubilization of active ingredients in the seed, and was stored in a desiccator for later use. M. oleifera Stock Solution: (Shelled Blended) Distilled water was added to the powder to make a suspension. The suspension was vigorously shaken for 30 minutes using a magnetic stirrer to promote water extraction of coagulant proteins and this suspension was filtered through Whatman No.1. Fresh solutions were prepared daily and kept refrigerated to prevent any aging effects (such as change in ph, viscosity and coagulation activity). Solutions were shaken vigorously before use. M. oleifera Stock Solution: (Shelled Blended Oil extracted / deoiled) The fine powder from the earlier step was used to remove all traces of oil from it. Oil was removed by mixing powder in 95% ethanol (5-10% w/v) for 30 minutes. The solids were separated by centrifugation and dried at room temperature for a period of 24 hours. From the dried sample, required amount of seed powder was mixed with distilled water. The suspension was vigorously shaken for 30 minutes, using magnetic stirrer to promote water extraction of coagulant proteins and this suspension was filtered through Whatman No.1. Fresh solutions were prepared daily and kept refrigerated to prevent any aging effects (such as change in ph, viscosity and coagulation activity). Solutions were shaken vigorously before use. Synthetic Turbid Water Stock Sample: The natural turbidity of raw water in most of the rural areas varies from NTU for maximum period. So work was carried out for water sample of three known turbidities of 50 (Low), 150(Medium) and 450(High) NTU. Bentonite and Kaolin clay turbidity samples were prepared. Five gram of Kaolin/Bentonite clay was mixed in CHAPTER 4 MATERIALS AND METHODS 32

50 500 ml of distilled water. The suspension was vigorously stirred for half an hour to facilitate uniform dispersion of clay particles. This suspension was allowed to stand for 24 hrs for complete hydration of Kaolin/Bentonite clay. The suspension was again stirred to obtain a uniform and homogenous suspension. The resulting suspension was found to have highly divided solids and used as stock solution for preparation of synthetic turbid water sample. The stock solution was used to prepare different turbidity samples varying from NTU by serial dilution. This synthetic water does not represent real water in country, but is a stable suspension used for this study. 4.6 EXTRACTION and PURIFICATION OF SEED POWDER: Selection & Optimization of Extraction Process Extraction of coagulant protein is carried out by various methods like salt precipitation, by organic solvents; heating of solution also precipitates out the proteins. Separation of Moringa coagulant was carried out by salt precipitation method. Sutherland et al (1994) proposed salt extraction method by using (2-3%) sodium chloride salt solution; Okuda et al (1999, 2001) extended this process further to purification of coagulant. Along with this, extraction can also be carried out with other salts and organic solvent. In the present work different salts like sodium chloride, potassium chloride, calcium chloride and ammonium sulfate were tried. Table No. 4.2: Extraction efficiency of different solvents Solvent Gm / 100 ml 3% Sodium chloride 6-7 gm 1% Potassium chloride gm 1.5% Calcium chloride 1-2 gm Saturated solution of ammonium sulfate gm As the extraction efficiency for sodium chloride is more and it is cheaper as compared to other solvents, 3% sodium chloride solvent was selected for extraction. CHAPTER 4 MATERIALS AND METHODS 33

51 Extraction of Protein from Seeds Dried powder of seeds was used for extraction. First the oil was removed from the powder by using ethanol. This de-oiled powder was weighed (50gm) & dispersed in to 3 % sodium chloride solution. It was continuously agitated for 12 hrs in orbital shaker, for leaching out of the protein from seed powder. Extract was filtered through Whatman filter paper No.44 and brown colored sodium chloride extract was obtained. This extract was further heated till white precipitate did not form at the bottom of solution. It was a separated crude coagulant protein which was further purified. Purification of Protein Heated crude protein extract was cooled and this solution was further poured in to the dialysis tube (Himedia. Mumbai) and kept for 12 hrs into the beaker containing cold water which was further kept in ice bath. After completion of dialysis, salts were removed out into the surrounding water solution and white protein remained inside the tube which was removed from the tube and rinsed with deionised water. This separated protein was homogenized with cold acetone for delipidization in a homogenizer to remove lipids. After delipidization this protein was dried at room temperature. M. oleifera Stock Solution: (Purified Protein): From the dried sample, required amount of protein powder was mixed with distilled water. The suspension was vigorously shaken for 30 minutes, using magnetic stirrer to promote water extraction of coagulant proteins and this suspension was filtered through Whatman No.1. Fresh solutions were prepared daily and kept refrigerated to prevent any aging effects (such as change in ph, viscosity and coagulation activity). Solutions were shaken vigorously before use. CHAPTER 4 MATERIALS AND METHODS 34

52 M. oleifera non-shelled & shelled seeds M.O. Seed Powder M. oleifera Seed Suspension Photo No. 4.1: Extraction of the Active Ingredient CHAPTER 4 MATERIALS AND METHODS 35

53 4.7 EXPERIMENT DESIGN: The complete experiment comprised rapid mixing followed by slow mixing and sedimentation. The residual turbidity was used as the parameter to judge the performance of the process. All care was taken throughout the course of experiments to ensure accuracy and reproducibility of the results. The parameters which affect the coagulation-flocculation process are as follows- 1) Initial turbidity (Type and concentration) 2) Dosage and type of coagulant extract 3) Physical and chemical characteristics of coagulant 4) Rapid mix velocity gradient 5) Rapid mix time 6) Slow mix velocity gradient 7) Slow mixing time 8) Settling time 9) Container geometry. Amongst above listed variables the scope of the work was limited to the optimization of coagulant dosage, container geometry, rapid mix velocity gradient and slow mix velocity gradient Coagulant Dose: The tests were performed using three different forms of coagulant i.e. a. shelled blended extract, b. shelled deoiled extract, and c. protein powder extract. The protein acts as coagulant to remove turbidity from the water. The shelled blended M. oleifera distilled water extract contain carbohydrates, proteins and fats. The shelled deoiled extract contains carbohydrates and proteins. Protein powder extract contain only proteins. The different doses were applied to evaluate the performance of these coagulants (Table 4.3). The dose which gave minimum residual turbidity was considered as the optimum dose. The experiments were performed as per IS on Jar test apparatus. At a time six jars were kept on the jar test apparatus. The varied doses of coagulant extracts were applied. Such three sets were performed and the optimum dose corresponding to the average residual turbidity was considered for that extract and turbidity. The bentonite clay and kaolin clay turbidity viz. 50, 150, and 450 NTU representing low, medium and moderately high range, respectively were used. CHAPTER 4 MATERIALS AND METHODS 36

54 Sr. Type of No. Extract 1 Shelled blended extract 2 Shelled deoiled extract 3 Protein powder extract Table No.4.3: Details of Coagulant Dose Bentonite Applied Dose mg/l Kaolin Applied Dose mg/l Turbidity Turbidity NTU NTU 50 30,35,40,45,50, ,50,60,70, ,90,100,110,120, ,120,130,140, ,210,220,230,240, ,200,250,300, ,20,25,30,35, ,50,100,150, ,70,80,90,100, ,50,100,150, ,180,190,200,210, ,100,150,200, ,20,30, ,40,50, Not performed ,100,120, Container Geometry: Four different configurations of jars were used in this study viz. circular and square jars, with and without baffles (Table No. 4.4 and Photo No. 4.2). Table No.4.4: Types of Jars with their dimension Sr. Type of jar No. of jars Dimensions (Internal) 1. Circular Non-Baffled (CNB) 6 10 cm (dia. in Plan) 14 cm (H) 2. Circular Baffled (CB) 3 10 cm (dia. in Plan) 14 cm (H) With 4 baffles(one at each quadrant point) of 1.1 cm 0.2 cm all along the height 3. Square Non-baffled (SNB) cm(l) 9.1 cm (B) 14 cm(h) 4. Square Baffled (SB) cm(l) 9.1 cm (B) 14 cm(h) With 4 baffles(one on each side) of 1.1 cm 0.2 cm all along the height CHAPTER 4 MATERIALS AND METHODS 37

55 Photo No. 4.2: Different types of Custom Made Jars CNB, CB, SNB, SB.(left to right) Rapid Mix velocity gradient (RMVG) and Slow Mix Velocity Gradient (SMVG): One of the variables of the jar test procedure is mixing intensity which is influenced by relative speed and configuration of agitator as well as the geometry of the mixing container. The present study aimed at determining the mixing intensity expressed as the mean velocity gradient, which is important parameter for designing of rapid mix and flocculation unit For laminar flow it is the rate of change of velocity with respect to distance in the direction perpendicular to the flow velocity and is generally expressed as mps/s or sec - 1 (IS ). The velocity gradient (G) is also defined as the square root of the ratio of power loss by shear per unit volume of fluid to the viscosity of the fluid and hence a dimension of 1/T (generally expressed as S -1 ). The value of G can be computed in terms of power input by following expression. Procedure followed for determination of velocity gradient (G):- G = P (1) V. μ Where, μ = Absolute Viscosity (N.s/m 2 ), P = Power input (N. m/s) V = Volume of mixing basin m 3 G = Velocity gradient, S -1 Where, P = D. v p (2) D = Drag force on paddles (N) CHAPTER 4 MATERIALS AND METHODS 38

56 Where, v p = Velocity of paddles relative to that of water (m/s) D = (C D. A P. ρ. v p 2 ) / 2 (3) C D = co-efficient drag, 1.8 for flat blades. A P = Area of paddles (m 2 ) ρ = Density of water (kg/ m 3 ) Where, N = rpm (No.) v p = π D N (4) 60 D = Diameter of blades (m) Sample Calculations:- N = 30 rpm D = 0.05 m. V = m 3 μ = N.sec/ m 3 v p = π D N 60 = (π ) / 60 = m/sec D = (C D. A P. ρ. v p 2 ) / 2 = ( )/2 = kg.m/sec 2. P = D v p = = Nm/sec 0.05 Fig: 4.1:Paddle showing 0.05 m Diameter G = P V. μ = ( / ) 1/2 = 40.2 s -1 CHAPTER 4 MATERIALS AND METHODS 39

57 Table 4.5 gives the values of velocity gradient for different paddle speeds (rpm) Table No. 4.5: rpm and its Corresponding velocity gradient rpm Velocity gradient (s -1 ) (Note: For the convenience of study the velocity gradient is taken as the Rotation per minute (RPM)) Rapid Mix Velocity Gradient selected for the experimentation: 250 s -1 (100 RPM), 330 s -1 (120 RPM), 415 s -1 (140 RPM), 505 s -1 (160 RPM) Slow Mix Velocity Gradient selected for the experimentation: 22 s -1 (20 RPM), 40 s -1 (30 RPM), 65 s -1 (40 RPM), 90 s -1 (60 RPM) CHAPTER 4 MATERIALS AND METHODS 40

58 4.8 EXPERIMENTATION: The experiments were performed in four stages. The details are as follows: STAGE-1 In Stage-1 optimum dose required for different initial turbidities like, 50 NTU (Low), 150 NTU (Medium) and 450 NTU (Moderately high) was determined while other parameters like container geometry/jar configurations, rapid and slow mix velocity gradient, settling time were kept constant for all the initial turbidity ranges. The circular non baffled jars were used. The rapid mixing was carried out at 120 rpm for 1 minute and slow mixing at 30 rpm for 15 minutes. The setting time was 15 minutes. Dose of coagulant, which was found to be optimum during the stage-1, was used in all the experiments of Stage-2, stage-3 and stage 4. Three coagulant extracts viz. shelled blended, deoiled and purified protein were used. Results were analyzed by establishing relationships between dosages versus respective residual turbidity. Residual turbidity was used as the parameter to judge the performance of the process. STAGE-2 In Stage-2 the effect of different container geometry in the removal of turbidity was studied. The CNB, CB, SNB and SB jars were used to evaluate the performance. The dose optimised in stage I was used while performing the experiments of Stage 2. The rapid mixing was carried out at 120 rpm for 1 minute and slow mixing at 30 rpm for 15 minutes. The settling time was 15 minutes. In this stage results were analyzed by working out the variations in the residual turbidity with respect to jar configurations. STAGE-3 In Stage 3, rapid mixing velocity gradient was varied. The dose optimised in Stage 1 and the container geometry optimised in Stage 2 were used in this stage. Stage-3 dealt with different velocity gradients like 250 s -1 (100 RPM), 330 s -1 (120 RPM), 415 s -1 (140 RPM), 505 s -1 (160 RPM). The slow mixing was carried out at 30 rpm for 15 minutes. The setting time was 15 minutes. STAGE-4 In Stage 4, slow mixing velocity gradient was varied. The dose optimised in Stage 1 and the container geometry optimised in Stage 2, the rapid mixing velocity gradient optimised in Stage 3 were used in this stage. Stage-4 dealt with different velocity gradients like 22 s -1 (20 RPM), 40 s -1 (30 RPM), 65 s -1 (40 RPM), 90 s -1 (60 RPM). The settling time was 15 minutes. CHAPTER 4 MATERIALS AND METHODS 41

59 Kaolin Clay: Manufacturer: LOBA CHEME Brand : Art Kaolin Extra Pure Bentonite clay: Manufacturer: MERCK Brand : Art Bentonite Extra Pure Turbidity determination: Turbidity was determined by Nephelometric method IS 3025 (Part 10) : It was measured by digital Lovibond Turbidity meter. Model, (Made in Germany). Photo No. 4.3: Digital Turbidity Meter Determination of ph: ph was determined by electrometric method IS 3025 (Part II) : 1983 ph was measured with Control Dynamics make ph meter. Experiment runs for jar test: In water treatment, the jar test has been and still is the mostly widely used method to evaluate coagulation- flocculation process. If procedures that simulate the treatment plant condition are followed, the jar test can produce correct results. Jar Test Apparatus: Jar test apparatus is generally used for determining optimum dosage of coagulant for coagulation-flocculation treatment (Hudson 1981). The jar testing apparatus contain six paddles which stir the six 1 liter containers. One container acts as a control while the operating conditions can be varied among the remaining five containers. An rpm gauge at the top center of device allows the uniform control of the mixing speed in the CHAPTER 4 MATERIALS AND METHODS 42

60 entire container. Rpm gauge was able to measure the rpm in the range of rpm. Apparatus is fitted with 6 rotator blades, each having area of 17 cm 2. Custom made jars were procured for the experimental runs. Photo No. 4.4: Jar Test apparatus with jars The procedure followed for the experiments was as follows: (According to Bureau of Indian Standards IS 3025 (PART 50): 2001) 1. A 500 ml of synthetic water sample of known composition and turbidity was taken in each custom made plastic jar under the rapid mix unit. One container was used as a control while the other 5 containers were used to vary experimental conditions. 2. Then the jars were placed under the agitator paddle (properly centered) for rapid mixing. 3. Using BIS standards, desired rapid mix velocity was applied to rapid mix for 1 min. 4. The appropriate dosages were added using pipette. 5. At the end of desired rapid mix time, the slow mix operation was performed.. 6. Immediately after slow mixing operation, the suspension was allowed to settle under quiescent conditions for 15 min. 7. At the end of settling period the supernatant water sample of ml was withdrawn from a level of cm below the surface and tested for residual turbidity (and ph in case of Alum) Residual aluminium concentration: The alluminium concentration in raw and treated drinking water was determined. The raw water was collected from Khadakwasala reservoir from where water is supplied to Pune city. The treated drinking water was collected from four areas of Pune City CHAPTER 4 MATERIALS AND METHODS 43

61 i.e. Katraj, Kothrud, Hadapsar and Koregaon park. The samples were collected in sterlised sampling bottles in the month of September, October, November and December The samples were analysed for residual aluminium concentration in these collected samples. The details are given in Chapter 5. Settling Column study: Similarly the settling column study was carried out to investigate the settling characteristics of the floc formed due to Moringa oleifera and alum coagulant. The details are given in Chapter 7. CHAPTER 4 MATERIALS AND METHODS 44

62 CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION 45

63 Chapter 5 Residual Aluminium concentration In this chapter, the significance of excess Aluminium in drinking water and the results of investigations of water quality of Pune city are explained. 5.1 INTRODUCTION The occurrence of aluminum in treated water has been considered for many years to be an undesirable aspect of treatment practice (Driscoll and Letterman, 1988). There is considerable concern throughout the world over the levels of aluminum found in drinking water sources (raw water) and treated drinking water. This has arisen mainly for two reasons. First, acid rain has caused the aluminum level in many freshwater sources to increase (Driscoll, 1988). A high (3.6 to 6 mg/l) concentration of aluminum in treated water gives rise to turbidity, reduces disinfection efficiency, and may precipitate as Al(OH) 3 during the course of distribution. Secondly, the possibility of an association between aluminum and neuropathological diseases including presenile dementia and Alzheimer s disease is frequently hypothesized (Driscoll, 1988). 5.2 ALUMINIUM IN WATER SUPPLIES The presence of Al in water for domestic supplies is due either to the addition of Al salts in the course of coagulation and flocculation treatment, or is caused by a low ph (ph = 5.5± 0.5) value of either surface or ground waters (Jekel, 1991). Driscoll and Letterman (1988) reported that approximately 11% of the Al input (through raw water and Al 2 (SO 4 ) 3 ) remained in the finished water as residual Al and was transported through the distribution system without any significant loss. They also found that high concentrations of Al in drinking water were related to both raw water concentrations and high treated-water turbidity. The major findings of the studies were that Al 2 (SO 4 ) 3 increased treated-water concentrations of Al, with the mean concentration values of Al from facilities using Al 2 (SO 4 ) 3 as a coagulant being approximately 0.1 mg/l; the Al concentrations in treated waters were, however, highly variable (0.05 to 0.25 mg/l). CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION 46

64 It is reported to be a 40 to 50% chance of increase in Al concentrations in drinking water over the concentrations in the raw water in plants using Al-based coagulants (Miller et al, 1984). It can be concluded that Al 2 (SO 4 ) 3 - treated waters generally contain more Al than raw surface waters. 5.3 WATER SUPPLY PROBLEMS Water supply problems associated with increased Al concentration in treated water include the formation of a hydrous Al precipitate in the distribution system which may increase turbidity and the number of complaints about clarity. Aluminium floc in the system may interfere with the disinfection process by enmeshing and protecting micro-organisms. Another problem attributed to increased Al concentration is deposition of Al hydrolysis products on pipe walls, which decreases carrying capacity. 5.4 HEALTH EFFECTS OF ALUMINIUM The presence of Al in drinking water has given rise to discussions on possible health effects, because of its suspected connection with Alzheimer s diseases or dialysis encephalopathy (Jekel, 1991). Crapper and Boni (1980) observed a relationship between Al and both Alzheimer s disease and dialysis encephalopathy in humans. Davidson et al. (1982) found that kidney dialysis patients suffered dementia when their dialysis fluid contained an Al concentration of 80 mg/l. Removal of Al from the fluid prior to dialysis decreased symptoms of dementia in patients. Driscoll and Letterman (1988) reported that dialysis patients exposed to elevated Al may exhibit dialysis encephalopathy, and/or bone mineralization disorders such as dialysis osteo- dystrophy. Martyn et al. (1989) based on a survey of 88 county districts in England and Wales reported that rate of Alzheimer s disease was 1.5 times higher in districts where the mean Al concentration exceeded 0.11 mg/l than in districts where concentrations were less than 0.01 mg/l. 5.5 WATER REQUIREMENTS AND SUPPLY OF PUNE CITY At present Pune city gets its water supply from Khadakwasla reservoir about 12 km from the city through right bank canal and a closed pipeline. Three more reservoirs CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION 47

65 i.e. Panshet, Warasgaon and Temghar have been constructed, upstream of Khadakwasla reservoir. The storage capacity of these 3 reservoirs is 900 MM 3 whereas the present annual requirement of city is about 200 MM 3. It is estimated that 80-90% of the population is connected through PMC water supply. PMC serves a water supply of 195 l/person-day (including water losses) against standard of 135 l/person-day. Existing and proposed water supply system Fig. No. 5.1: Existing water supply system of Pune city In year 1997, the area under the jurisdiction of Pune Municipal Corporation, increased due to merger of 38 villages around Pune City into the Corporation Limits. The Km 2 of area within old PMC Limits increased to 430 Km 2 in the year There has been sudden increase of about 40% population load on the available municipal services like water and sanitation. CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION 48

66 Although large portion of aluminium intake by humans comes from food, presently there is much concern on the presence of aluminium in drinking water. This research is focused on study of drinking water quality at end users of Pune city. 5.6 Sampling: The water samples were collected from source of water supply i.e. Khadakwasla reservoir and four different areas of Pune city. The areas were Katraj, Kothrud, Hadapsar and Koregaon Park. The samples were collected (IS 3025 Part 55: 2003) from these four different areas once in a month of September, October, November and December. Only one sample was collected from Khadakwasla reservoir. These were analysed for residual Aluminium concentration in the laboratory as per IS 3025 (Part 55): RESULTS: Results of analysis of the samples are shown in Table 5.1 and represented in Fig no Table No.5.1: Aluminium and ph of water samples STUDY AREA September October November December January Al (mg/l) ph Al (mg/l) ph Al (mg/l) ph Al (mg/l) ph Al (mg/l) ph Katraj < < < Kothrud < < < < Koregaon Park < < < Hadapsar < < < Khadakwasla Reservoir < < < CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION 49

67 Fig. No. 5.2: Aluminium as (Al) in different areas of Pune city 5.8 DISCUSSION Several studies have shown that a portion of alum added to the water is not removed and remains as residual aluminum in the treated water (Miller et al. 1984, Letterman and Driscoll 1988). According to Indian Standards (BIS 10500) the desirable limit for aluminium concentration in treated water is 0.03 mg/l, but its permited up to 0.2 mg/l. The results of aluminium in drinking water samples collected from Pune city in the month of September found to be in the range of < 0.03 mg/l to 0.18 mg/l in which Katraj showing 0.09 mg/l, Kothurd < 0.03 mg/l, Koregoan park 0.11 mg/l and hadapsar 0.18 mg/l. Fig indicates that aluminum concentration from Kothrud area is below desirable limit,aluminum concentration from Katraj, Koregaon park and Hadapsar areas are within the permissible limit. Aluminum in drinking water samples collected from Pune city in the month of October was found to be in the range of < 0.03 mg/l to 0.08 mg/l in which Katraj showing < 0.03 mg/l, Kothrud 0.05 mg/l, Koregoan Park <0.03 mg/l, and Hadapsar 0.08 mg/l. Fig indicates that aluminium concentration from Katraj & Koregoan Park areaes is below desirable limit, aluminum concentration from Kothrud & Hadapsar areas are within the permissible limit. Aluminium in drinking water samples collected from Pune city in the month of November found to be in the range of <0.03 mg/l to 0.06 mg/l in which Katraj CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION 50

68 showing 0.05 mg/l, Kothrud <0.03 mg/l, Koregoan Park 0.06 mg/l, Hadapsar <0.03 mg/l. Fig indicates that Aluminium concentration from Kothrud & Hadapsar areas is below desirable limit, aluminum concentration from Katraj & Koregoan park areaes are within the permissible Limit. Aluminium in drinking weater samples collected from Pune city in the month of December & January found to be all below < 0.03 mg/l which is desirable limit. 5.9 CONCLUSION Aluminium in drinking weater samples collected from Pune city in the month of October indicates that Aluminium concentration from Katraj & Koregoan Park area is below Desirable Limit whereas in Kothrud and Hadapsar area is between desirable limit and permisssible limit. Aluminium in drinking water samples collected from Pune city in the month of November indicates that Aluminium concentration from Kothrud & Hadapsar area is below desirable limit whereas Katraj and Koregaon Park area is between desirable and permissible limit. Aluminium in drinking water samples collected from Pune city in the month of December & January was found to be all below <0.03 mg/l which is desirable limit. It was observed from the analysis that the aluminium concentration of the raw water of Khadakwasla dam was < 0.03mg/L, which is below the desirable limit. Comparing the results, aluminium concentration of the raw water and treated drinking water showed that the concentartion of aluminium in treated drinking water is more for some time during the period of observation. This indicates that there is an increase in the aluminum concentration due to the addition of alum or PAC in the water during treatment. CHAPTER 5 RESIDUAL ALUMINIUM CONCENTRATION 51

69 CHAPTER 6 RESULTS CHAPTER 6 RESULTS 52

70 Chapter 6 Results This chapter includes I. The results of the M. O. seed analysis II. The results of the Optimisation of dose, Container Geometry (Jar Configuration), Rapid Mix Velocity Gradient and Slow Mix Velocity Gradient 6.0 SEED ANALYSIS The M. O. tree dried seeds were collected from four districts of Maharashtra. The coning quartering method was used to obtain a representative sample. The representative sample of 500 gm was collected. The required quantity of seeds was sent to the National Agriculture and Food Analysis and Research Institute, Pune. The results are as follows: Table No. 6.00: Results of Seed Analysis Parameters Results Test Method Protein % AOAC Fat % Ranganna Carbohydrates % IS: Crude Fiber % SP-18 (P-IX) 1984 Moisture 6.41 % Ranganna Ash 3.06 % AOAC Coagulation mechanism of M. O. could be adsorption and charge neutralization. Coagulant activities of M. O. are known due to the synergistic effect of proteins comprising glutamine, methionine, arginine, proline etc. It is observed that the protein (the active coagulant) present in the kernel of the seed is 36.9 %. The fat and the carbohydrates content in the seed is 37.25% and 16.38% respectively. As the coagulant protein helps in the turbidity removal, the extraction and the purification of the seed powder was carried out to evaluate the performance of the various forms of the coagulant and to assess whether it would be necessary to give adequate treatment to the seeds before their use as coagulants because purification has cost effect. CHAPTER 6 RESULTS 53

71 6.1 OPTIMISATION OF THE DOSE The Bentonite and Kaolin clay were used to prepare 50, 150, 450 NTU turbidity samples. The M. O. shelled blended, deoiled and purified protein extracts were used to investigate the effect of purification on the optimum dose. The experiments were performed as per IS 3025 (Part 50):2001. Circular non baffled 6 jars were used to perform the jar tests. Two sets of the experiments were performed to determine the average residual turbidity. The varied dose of the coagulant extracts was applied to the jars. The dose which showed minimum average residual turbidity was considered as the Optimum dose Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended 4. Jars Circular Non Baffled 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min Dose 6. Variable 50 NTU 30,35,40,45,50,55 mg/l 150NTU 80,90,100,110,120,130 mg/l 450 NTU 200,210,220,230,240,250 mg/l As per IS 3025 (Part 50):2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 54

72 Table No. 6.1: Dose optimization (M.O.Shelled Blended) Bentonite 50 NTU Jar CNB Dosage (mg/l) Residual Turbidity(NTU) SET-I SET-II Avg. Residual Turbidity NTU Table No.6.2: Dose optimization (M.O. Shelled Blended) Bentonite 150 NTU Jars CNB Dosage (mg/l) Residual Turbidity(NTU) SET-I SET-II Avg. Residual Turbidity NTU Table No. 6.3: Dose optimization (M.O. Shelled Blended) Bentonite 450 NTU Jars CNB Dosage (mg/l) Residual Turbidity(NTU) SET-I SET-II Avg. Residual Turbidity NTU CHAPTER 6 RESULTS 55

73 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.1: M.O. Shelled Blended Bentonite Clay 50 NTU Applied Dose mg/l Fig. No. 6.2:M.O. Shelled Blended Bentonite Clay 150 NTU Applied Dose mg/l Fig. No. 6.3: M.O. Shelled Blended Bentonite Clay 450 NTU Applied Dose mg/l CHAPTER 6 RESULTS 56

74 6.1.2 Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled 4. Jars Circular Non Baffled 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min Dose 6. Variable 50 NTU 15,20,25,30,35,40 mg/l 150NTU 60,70,80,90,100,110 mg/l 450 NTU 170,180,190,200,210,220 mg/l Initial Turb. RMVG As per IS 3025 (Part 50):2001 Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 57

75 Table No.6.4: Dose Optimization (M.O. Deoiled) Bentonite 50 NTU Jar CNB Dosage (mg/l) Residual Turbidity(NTU) Set I Set II Avg. Residual Turbidity (NTU) Table No. 6.5: Dose Optimization (M.O. Deoiled) Bentonite 150 NTU Jar CNB Dosage (mg/l) Residual Turbidity(NTU) Set I Set II Avg. Residual Turbidity (NTU) Table No. 6.6: Dose Optimization (M.O. Deoiled) Bentonite 450 NTU Jar CNB Dosage (mg/l) Residual Turbidity(NTU) Set I Set II Avg. Residual Turbidity (NTU) CHAPTER 6 RESULTS 58

76 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig.No. 6.4: M.O. Deoiled Bentonite Clay 50 NTU Applied Dose mg/l Fig. No. 6.5: M.O. Deoiled Bentonite Clay 150 NTU Applied Dose mg/l Fig. No. 6.6:M.O. Deoiled Bentonite Clay 450 NTU Applied Dose mg/l CHAPTER 6 RESULTS 59

77 6.1.3 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended 4. Jars Circular Non Baffled 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min Dose 6. Variable 50 NTU 40,50,60,70,80 mg/l 150 NTU 110,120,130,140,150 mg/l 450 NTU 150,200,250,300,350 mg/l As per IS 3025 (Part 50):2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 60

78 Table No. 6.7: Dose Optimisation (M.O Shelled Blended) KAOLIN 50 NTU Jar Dosage (mg/l) Resi. Turb. (NTU) Set I Set II Set-III Avg. Turb. (NTU) CNB Table No. 6.8: Dose Optimisation (M.O Shelled Blended) KAOLIN 150 NTU Jar Dosage (mg/l) Resi. Turb. (NTU) Set I Set II Set-III Avg. Turb. (NTU) CNB Table No. 6.9: Dose Optimisation (M.O Shelled Blended) KAOLIN 450 NTU Jars Dosage (mg/l) Resi. Turb. (NTU) Set I Set II Set-III Avg. Turb. (NTU) CNB CHAPTER 6 RESULTS 61

79 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.7: M.O. Shelled Blended Kaolin Clay 50 NTU Applied Dose mg/l Fig. No. 6.8: M.O. Shelled Blended Kaolin Clay 150 NTU Applied Dose mg/l Fig. No. 6.9: M.O. Shelled Blended Kaolin Clay 450 NTU Applied Dose mg/l CHAPTER 6 RESULTS 62

80 6.1.4 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled 4. Jars Circular Non Baffled 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min Dose 6. Variable 50 NTU 10,50,100,150,200 mg/l 150 NTU 10,50,100,150,200 mg/l 450 NTU 10,50,100,150,200 mg/l As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 63

81 Table No. 6.10: Dose Optimisation (M.O.Deoiled) KAOLIN 50 NTU Jars Dosage Resi. Turb. (NTU) Avg. Turb. (mg/l) Set I Set II Set-III (NTU) CNB Table No. 6.11: Dose Optimisation (M.O. Deoiled) KAOLIN 150 NTU Jars Dosage Resi. Turb. (NTU) Avg. Turb. (mg/l) Set I Set II Set-III (NTU) CNB Table No. 6.12: Dose Optimisation (M. O. Deoiled) KAOLIN 450 NTU Jars Dosage Resi. Turb. (NTU) Avg. Turb. (mg/l) Set I Set II Set-III (NTU) CNB CHAPTER 6 RESULTS 64

82 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.10: M.O. Deoiled Kaolin Clay 50 NTU Applied Dose mg/l Fig. No. 6.11:M.O. Deoiled Kaolin Clay 150 NTU Applied Dose mg/l Fig. No. 6.12: M.O. Deoiled Kaolin Clay 450 NTU Applied Dose mg/l CHAPTER 6 RESULTS 65

83 6.1.5 Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Purified Protein Sr. No. Type Description 1 Clay Bentonite clay 2 Turbidity 50, 150,450 NTU 3 Extract M.O. Purified Protein Powder 4 Jars Circular Non Baffled 5 Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min Dose 6 Variable 50 NTU 10,20,30, 40 mg/l 150 NTU 30,40,50,60 mg/l 450 NTU 80,100,120,130 mg/l As per IS 3025 (Part 50):2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 66

84 Table No. 6.13: Dose Optimisation (M.O. Protein Powder) at Bentonite 50 NTU Jar CNB Dosage (mg/l) Residual Turbidity(NTU) Set I Set II Avg. Residual Turbidity (NTU) Table No. 6.14: Dose Optimisation (M.O. Protein Powder) at Bentonite 150 NTU Jar CNB Dosage (mg/l) Residual Turbidity(NTU) Set I Set II Avg. Residual Turbidity (NTU) Table No. 6.15: Dose Optimisation (M.O. Protein Powder) at Bentonite 450 NTU Jar CNB Dosage (mg/l) Residual Turbidity(NTU) Set I Set II Avg. Residual Turbidity (NTU) CHAPTER 6 RESULTS 67

85 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.13: M.O. Protein Powder 50 NTU Applied Dose mg/l Fig. No. 6.14: M.O. Protein Powder 150 NTU Applied Dose mg/l Fig. No. 6.15: M.O. Protein Powder 450 NTU Applied Dose mg/l CHAPTER 6 RESULTS 68

86 6.1.6 Observations: 1. For 50, 150 and 450 NTU initial Bentonite clay turbidity, the % removal of turbidity is 80, 90, 97 % for shelled blended extract and 74, 92, 97 % for deoiled extract respectively. 2. For 50, 150 and 450 NTU initial Kaolin clay turbidity, the % removal of turbidity is 52, 79, 91 % for shelled blended extract and 55, 79, 93 % for deoiled extract respectively. 3. The % turbidity removal is more in case of Bentonite clay turbidity as compared to the Kaolin clay turbidity. 4. The optimum dose of M.O. shelled blended extract for Kaolin clay turbidity of 50 NTU, 150 NTU, 450 NTU is increased by 40 %, 8.3% and 25 % respectively than for Bentonite clay turbidity. 5. The optimum dose of M.O. deoiled extract for Kaolin clay turbidity of 50 NTU is 43 % more than for Bentonite clay turbidity. 6. The optimum dose of M.O. deoiled extract for 150 NTU, 450 NTU Bentonite clay and Kaolin clay turbidity is same. 7. The optimum dose of M.O. shelled blended extract for 150 NTU initial turbidity is more than that of 50 NTU initial turbidity. It has been increased by 140 % for Bentonite clay and 85.7 % for Kaolin clay turbidity. 8. The optimum dose of M.O. deoiled extract for 150 NTU initial turbidity is more than that of 50 NTU initial turbidity. It has been increased by % for Bentonite clay and 100 % for Kaolin clay turbidity. 9. The optimum dose of M.O. shelled blended extract for 450 NTU initial turbidity is more than that of 150 NTU turbidity. It has been increased by 100 % for Bentonite clay and % for Kaolin clay turbidity. 10. The optimum dose of M.O. deoiled extract for 450 NTU initial turbidity is more than that of 150 NTU turbidity. It has been increased by 100 % for Bentonite clay and Kaolin clay turbidity. 11. The optimum dose for 50, 150 and 450 NTU Kaolin turbidity is more as compared to Bentonite clay turbidity. 12. For all concentration of Bentonite and Kaolin clay turbidity the optimum dose of protein powder required is the least as compared to shelled blended extract and deoiled extract Discussions: The optimum dose of M.O. extract was increased with increase in initial turbidity of the water samples. This result is in agreement with the results reported by Muyibi and Evison (1995). The results of overall turbidity reduction agree with those of Jahn (1986), Folkard (1989) and Muyibi (1995). CHAPTER 6 RESULTS 69

87 It is observed that as initial turbidity of water sample increases, the % turbidity removal also increases. This observation may be explained in terms of the increase in suspended particles available for adsorption and inter particle bridge formation. The net effect is increase in particle collision frequency and agglomeration rate (LaMer and Healy, 1968). There is about 20 to 45 % reduction in the optimized dose of M.O. deoiled extract than M.O. shelled blended extract. This reduction in the dose is significant. Moringa oleifera being a short chain cationic polyelectrolyte, the turbidity removal is through electrostatic path mechanism which is a surface phenomenon. The oil content in the seed will form an emulsion of film coating which may inhibit contact with the surface of reaction and thus reduce floc formation. The extraction of oil may therefore enhance the turbidity removal resulting in better coagulation and flocculation. There is about 60 % reduction in the optimized dose of M.O. purified protein extract than M. O. shelled blended extract. Also there is about 50 % reductions in the optimised dose of M. O. purified protein extract than M.O. deoiled extract. The difference in the optimised dose of M.O. shelled blended, deoiled and purified protein is because of active proteins present in the kernel. This is in agreement with the results obtained by Ndabigengesere and Narasiah (1998). The crude M.O. extract contains compounds other than proteins such as carbohydrates, lipids, other organic molecules and inorganic substances that may be released in water (Ghebremichael and Gunratna, 2005). It is observed that for M.O. shelled blended extract, low to moderate Kaolin clay initial turbidities of 50 and 150 NTU, the optimum dose was 70 and 130 mg/l while for 450 NTU, it was 300 mg/l. This result is in agreement with the theory of polymer bridging (LaMer and Healy, 1963) since M.O. is a natural polyelectrolyte (Jahn, 1986). Furthermore since M.O. is a cationic polyelectrolyte (Folkard, 1989) increasing dosages ultimately leads to charge reversal and subsequent restabilisation of destabilized particles (Weber, 1972) The optimum dosages obtained in this study are found lesser than those reported by Muyibi and Evison (1995) and S. Katayon et al (2004). This difference is probably due to usage of different species of M.O. According to Jahn (1998) about 14 species of M.O. have so far have been identified and although all M. O. suspensions acted as primary coagulants, but the different species did not have same coagulation efficiency. CHAPTER 6 RESULTS 70

88 6.1.8 Conclusion: Different species of M. O. did not have same coagulation efficiency. When M. O. was used in coagulating Bentonite and Kaolin suspensions, the initial turbidity of water and M.O. extract were found to be highly significant. Increasing dose of M.O. leads to decrease in turbidity up to optimum dose after which the residual turbidity increases due to floc restabilisation. The purification showed better coagulation activity in terms of turbidity removal with lower dosages than the crude M.O. extracts. The M. O. coagulant protein could effectively remove more than 95% of turbidity for high turbid waters. More turbidity removal efficiency is obtained for water samples of high initial turbidity. CHAPTER 6 RESULTS 71

89 6.2 Optimisation of Container Geometry/ Jar Configuration The dose optimised in the earlier stage was utilized for optimisation of the jar configuration. The Circular Non Baffled (CNB), Circular Baffled (CB), Square Non Baffled (SNB), Square Baffled (SB) containers were used to investigate the effect of jar configuration in the turbidity removal. The Bentonite and Kaolin clay turbidity (50, 150, 450 NTU) were used to understand the effect of type and concentration of turbidity on jar configuration. The experiments were performed as per IS 3025 (Part 50):2001. Three sets of experiments were performed to obtain the average residual turbidity. The minimum residual turbidity was considered as indicator of good performance for turbidity removal. The plan area of container, the liquid volume and hence the depth for all four containers used in the experiments were the same irrespective of their geometry Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Jars CNB, CB, SNB, SB Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended 4. Dose (Optimised in Stage I) For 50 NTU: 50 mg/l 150 NTU: 120 mg/l 450 NTU: 240 mg/l 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min 6. Variable Jars: CB, CNB, SB, SNB As per IS 3025 (Part 50):2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 72

90 Table No. 6.16: Jar Optimisation (M.O. Shelled Blended) Bentonite 50 NTU Dosage (mg/l) 50 Residual Turbidity NTU Average Residual Jars Turbidity SET-I SET-II SET III NTU CB CNB SB SNB Table No.6.17: Jar Optimisation (M.O Shelled Blended) Bentonite 150 NTU Dosage (mg/l) 120 Jars CB CNB SB SNB Residual Turbidity NTU SET-I SET-II SET III Average Residual Turbidity NTU Table No. 6.18: Jar Optimisation (M.O Shelled Blended) Bentonite 450 NTU Dosage (mg/l) 240 Jars CB CNB SB SNB Residual Turbidity NTU SET-I SET-II SET III Average Residual Turbidity NTU CHAPTER 6 RESULTS 73

91 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.16: M.O. Shelled Blended Bentonite Clay 50 NTU CB CNB SB SNB Jar Type Fig. No. 6.17: M.O. Shelled Blended Bentonite Clay 150 NTU CB CNB SB SNB Jar Type Fig. No. 6.18: M.O. Shelled Blended Bentonite Clay 450 NTU CB CNB SB SNB Jar Type CHAPTER 6 RESULTS 74

92 6.2.2 Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled Jars CNB, CB, SNB, SB Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled 4. Dose ( Optimised in stage I) For 50 NTU: 35 mg/l 150 NTU: 100 mg/l 450 NTU: 200 mg/l 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min 6. Variable Jars: CB, CNB, SB, SNB As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 75

93 Table No. 6.19: Jar Optimisation (M.O. Deoiled) Bentonite 50 NTU Dosage (mg/l) 35 Jars Residual Turbidity NTU Average Residual Turbidity Set I Set II SET III NTU CB CNB SB SNB Table No. 6.20: Jar Optimisation (M.O. Deoiled) Bentonite 150 NTU Dosage (mg/l) 100 Jars Residual Turbidity NTU Average Residual Turbidity Set I Set II SET III NTU CB CNB SB SNB Table No. 6.21: Jar Optimisation (M.O. Deoiled) Bentonite 450 NTU Dosage (mg/l) 200 Residual Turbidity NTU Average Residual Jars Turbidity Set I Set II SET III NTU CB CNB SB SNB CHAPTER 6 RESULTS 76

94 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.19:M.O. Deoiled Bentonite Clay 50 NTU CB CNB SB SNB Jar Type Fig. No. 6.20:M.O. Deoiled Bentonite Clay 150 NTU CB CNB SB SNB Jar Type Fig. No. 6.21: M.O. Deoiled Bentonite Clay 450 NTU CB CNB SB SNB Jar Type CHAPTER 6 RESULTS 77

95 6.2.3 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Jars CNB, CB, SNB, SB Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended 4. Dose ( Optimised in stage I) For 50 NTU: 70 mg/l 150 NTU: 130 mg/l 450 NTU: 300 mg/l 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min 6. Variable Jars: CB, CNB, SB, SNB As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 78

96 Table No. 6.22: Jar Optimisation (M.O Shelled Blended) KAOLIN 50 NTU Dosage (mg/l) Jars Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) CB CNB SB SNB Table No. 6.23: Jar Optimisation (M.O Shelled Blended) KAOLIN 150 NTU Dosage (mg/l) Jars Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) CB CNB SB SNB Table No. 6.24: Jar Optimisation (M.O Shelled Blended) KAOLIN 450 NTU Dosage (mg/l) Jars Resi. Turb. (NTU) Set I Set II Set-III Avg. Turb. (NTU) CB CNB SB SNB CHAPTER 6 RESULTS 79

97 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.22: M.O. Shelled Blended Kaolin Clay 50 NTU CB CNB SB SNB Jar Type Fig. No. 6.23: M.O. Shelled Blended Kaolin Clay 150 NTU CB CNB SB SNB Jar Type Fig.No. 6.24: M.O. Shelled Blended Kaolin Clay 450 NTU CB CNB SB SNB Jar Type CHAPTER 6 RESULTS 80

98 6.2.4 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended Jars CNB, CB, SNB, SB Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled 4. Dose (Optimised in stage I)) For 50 NTU: 50 mg/l 150 NTU: 100 mg/l 450 NTU: 200 mg/l 5. Velocity Gradient Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 30 rpm (40 s -1 ), 15 min 6. Variable Jars: CB, CNB, SB, SNB Initial Turb. RMVG As per IS 3025 (Part 50) :2001 Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 81

99 Table No. 6.25: Jar Optimisation (M. O. Deoiled) Kaolin 50 NTU Dosage (mg/l) Jars Resi. Turb. (NTU) Avg. Turb. Set I Set II Set-III (NTU) CB CNB SB SNB Table No. 6.26: Jar Optimisation (M.O. Deoiled) Kaolin 150 NTU Dosage (mg/l) 100 Jars CB CNB SB SNB Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) Table No. 6.27: Jar Optimisation (M.O. Deoiled) Kaolin 450 NTU Dosage (mg/l) 150 Jars CB CNB SB SNB Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) CHAPTER 6 RESULTS 82

100 Av. Residual Turbidity NTU Av. Residual Turbidity NTU Av. Residual Turbidity NTU Fig. No. 6.25: M.O. Deoiled Kaolin Clay 50 NTU CB CNB SB SNB Jar Type Fig. No. 6.26: M.O. Deoiled Kaolin Clay 150 NTU CB CNB SB SNB Jar Type Fig. No. 6.27: M.O. Deoiled Kaolin Clay 450 NTU CB CNB SB SNB Jar Type CHAPTER 6 RESULTS 83

101 6.2.5 Discussion and Conclusion: The experiments were performed with four different containers at a time in the jar test apparatus. Such 36 sets were performed in this jar optimisation study. In the present study it was observed that the efficiency of removal of Kaolin clay turbidity increases for the system geometries in the following order: SNB, SB, CNB and CB. In case of Bentonite clay turbidity the efficiency of removal of turbidity increases for the system geometries in the following order: SNB, CNB, SB and CB, except for 50 NTU turbidity which is SNB, SB, CNB and CB. The results are not in agreement with Mhaisalkar (1986). But the SB and CB being first two geometries showing better performance agrees with Mhaisalkar (1986) that for a given impeller speed, the energy input for a baffled container is more than that for the container with no baffles. For all the experiments performed so far, the best results were obtained with Circular Baffled (CB) jar for turbidity removal. It showed the minimum residual turbidity for all values of initial turbidity of water samples. The results are not in agreement with Leentvar (1980) who reported square tanks give best results in coagulation flocculation experiments. It is concluded that based on the results obtained in this study of optimisation of jar configuration / container geometry, the Circular Baffled (CB) jar is most suitable. CHAPTER 6 RESULTS 84

102 6.3 OPTIMIZATION OF RAPID MIXING VELOCITY GRADIENT The dose optimised in part 6.1 and the Jar / Container optimised in part 6.2 were used in this stage. The jar optimised was Circular Baffled, which exhibited the better performance for removal of turbidity, was considered to optimise the rapid mix velocity gradient. The experiments were performed as per IS 3025 (Part 50):2001. The rapid mixing time was kept constant and the RPM was changed. The RPMs considered were 100 (250 S -1 ), 120 (329 S -1 ), 140 (415 S -1 ), 160 (507 S -1 ). The figures in the brackets indicate the corresponding Velocity Gradient of the RPM. The effect of, variations in the RPM during mixing of the chemical, on turbidity removal was investigated Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended, RMVG 250S -1, 329 S -1, 415 S -1, 507 S -1 Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended 4. Dose (Optimised in stage I) 5. Jars (Optimised in stage II) CB For 50 NTU: 50 mg/l 150 NTU: 120 mg/l 450 NTU: 240 mg/l 6. Velocity Gradient 7. Variable Slow Mix : 30 rpm (40 s -1 ), 15 min Rapid Mix: 100 RPM (250S -1 ), 120 RPM (329 S -1 ), 140 RPM (415 S -1 ), 160 RPM (507 S -1 ) As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU? 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 85

103 Table No. 6.28: Rapid Mix V. G. (M.O. Shelled Blended) Bentonite 50 NTU Dosage mg/l Jars RPM Residual Turbidity (NTU) SET-I SET-II Average Residual Turbidity (NTU) Average CB Table No. 6.29: Rapid Mix V. G. (M.O. Shelled Blended) Bentonite 150 NTU Dosage mg/l Jar RPM Residual Turbidity(NTU) SET-I SET-II Average Residual Turbidity (NTU) Average CB CHAPTER 6 RESULTS 86

104 Av. Residual Turbidity NTU Table No. 6.30: Rapid Mix V. G. (M.O. Shelled Blended) Bentonite 450 NTU Dosage mg/l Jar 240 CB RPM Residual Turbidity(NTU) Average Residual Turbidity (NTU) SET-I SET-II Average Fig.No. 6.28: RMVG Shelled Blended Bentonite Clay 50 NTU 150 NTU 450 NTU RPM 100 RPM 120 RPM 140 RPM 160 From Fig. No. 6.28, it is observed that for 50, 150, 450 NTU initial turbidity, the minimum average residual turbidity, is 9.1, 13 and 13.7 NTU respectively. The optimal velocity gradient for these residual turbidities of 9.1, 13 and 13.7 NTU is 120, 120 and 140 RPM. The increase in velocity gradient for 450 NTU initial turbidity may be due to high energy requirement for the dispersal of coagulant in raw water. CHAPTER 6 RESULTS 87

105 6.3.2 Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled RMVG 250S -1, 329 S -1, 415 S -1, 507 S -1 Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled Dose (Optimised in stage I) Jars (Optimised in stage II) For 50 NTU: 35 mg/l 150 NTU: 100 mg/l 450 NTU: 200 mg/l CB 6. Velocity Gradient Slow Mix : 30 rpm(40 s -1 ), 15 min 7. Variable Rapid Mix: 100 RPM (250S -1 ), 120 RPM (329 S -1 ), 140 RPM (415 S -1 ), 160 RPM (507 S -1 ) As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU? 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 88

106 Table No. 6.31: Rapid Mix V. G. (M.O. Deoiled) Bentonite 50 NTU Dosage mg/l Jar 35 CB RPM Residual Turbidity(NTU) Average Residual Turbidity (NTU) SET-I SET-II Average Table No. 6.32: Rapid Mix V. G. (M.O. Deoiled) Bentonite 150 NTU Dosage mg/l Jar 100 CB RPM Residual Turbidity(NTU) Average Residual Turbidity (NTU) SET-I SET-II Average CHAPTER 6 RESULTS 89

107 Av. Residual Turbidity NTU Table No. 6.33: Rapid Mix V. G. (M.O. Deoiled) Bentonite 450 NTU Dosage mg/l Jar 200 CB RPM Residual Turbidity(NTU) Average Residual Turbidity (NTU) SET-I SET-II Average Fig. No. 6.29: RMVG Deoiled Bentonite Clay 50 NTU 150 NTU 450 NTU RPM 100 RPM 120 RPM 140 RPM 160 From Fig. No. 6.29, it is observed that for 50, 150, 450 NTU initial turbidity, the minimum average residual turbidity, is 10.9, 12.9 and 15.9 NTU respectively. The optimal velocity gradient for these residual turbidities of 10.9, 12.9 is 120 RPM and for 15.9 NTU it is 140 RPM. CHAPTER 6 RESULTS 90

108 6.3.3 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended RMVG 250S -1, 329 S -1, 415 S -1, 507 S -1 Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended Dose ( Optimised in stage I) Jars (Optimised in stage II ) For 50 NTU: 70 mg/l 150 NTU: 130 mg/l 450 NTU: 300 mg/l CB 6. Velocity Gradient Slow Mix : 30 rpm(40 s -1 ), 15 min Rapid Mix: 7. Variable 100 RPM (250S -1 ), 120 RPM (329 S -1 ), 140 RPM (415 S -1 ), 160 RPM (507 S -1 ) As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU? 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 91

109 Table No. 6.34: Rapid Mix V. G. M.O. Shelled Blended Kaolin 50 NTU Dosage (mg/l) Jar 70 CB RPM Resi. Turb. (NTU) Avg. Turb. Set I Set II Set III (NTU) Table No Rapid Mix V. G. M.O. Shelled Blended Kaolin 150 NTU Dosage (mg/l) Jar 130 CB RPM Resi. Turb. (NTU) Avg. Turb. Set I Set II Set III (NTU) Table No. 6.36: Rapid Mix V. G. M.O. Shelled Blended Kaolin 450 NTU Dosage (mg/l) Jar 300 CB RPM Resi. Turb. (NTU) Avg. Turb. Set I Set II Set III (NTU) CHAPTER 6 RESULTS 92

110 Av. Residual Turbidity NTU Fig. No. 6.30: RMVG Shelled Blended Kaolin Clay 50 NTU 150 NTU 450 NTU RPM 100 RPM 120 RPM 140 RPM 160 From Fig. No. 6.30, it is observed that for 50, 150, 450 NTU initial turbidity, the minimum average residual turbidity, is 13.55, and NTU respectively. The optimal velocity gradient for these residual turbidities of 13.55, and NTU is 120, 120 and 140 RPM. The increase in velocity gradient for 450 NTU initial turbidity may be due to high energy requirement for the dispersal of coagulant in raw water. CHAPTER 6 RESULTS 93

111 6.3.4 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled RMVG 250S -1, 329 S -1, 415 S -1, 507 S -1 Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled Dose ( Optimised in stage I ) Jars ( Optimised in stage II ) Velocity Gradient For 50 NTU: 50 mg/l 150 NTU: 100 mg/l 450 NTU: 200 mg/l CB Slow Mix : 30 rpm(40 s -1 ), 15 min Rapid Mix: 7. Variable 100 RPM (250S -1 ), 120 RPM (329 S -1 ), 140 RPM (415 S -1 ), 160 RPM (507 S -1 ) As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU? 1 min 30 rpm (41 s -1 ) 15 min 15 min CHAPTER 6 RESULTS 94

112 Table No. 6.37: Rapid Mix V. G. (M.O. Deoiled) Kaolin 50 NTU Dosage (mg/l) Jar 50 CB RPM Resi. Turb. (NTU) Avg. Turb. Set I Set II Set III (NTU) Table No. 6.38: Rapid Mix V. G. (M.O. Deoiled) Kaolin 150 NTU Dosage (mg/l) Jar 100 CB RPM Resi. Turb. (NTU) Avg. Turb. Set I Set II Set III (NTU) Table No. 6.39: Rapid Mix V. G. (M.O. Deoiled) Kaolin 450 NTU Dosage (mg/l) Jar 150 CB RPM Resi. Turb. (NTU) Avg. Turb. Set I Set II Set III (NTU) CHAPTER 6 RESULTS 95

113 Av. Residual Turbidity NTU Fig. No. 6.31: RMVG Deoiled Kaolin Clay 50 NTU 150 NTU 450 NTU RPM 100 RPM 120 RPM 140 RPM Observations and Discussion: From Fig. No. 6.31, it is observed that for 50, 150, 450 NTU initial turbidity, the minimum average residual turbidity, is 11.18, and NTU respectively. The optimal velocity gradient for these residual turbidities is 120, 120 and 140 RPM respectively. The increase in velocity gradient for 450 NTU initial turbidity may be due to high energy requirement for the dispersal of coagulant in raw water. Optimisation of rapid mix velocity gradient was carried out on water samples of Bentonite and Kaolin initial turbidities of 50, 150, 450 NTU. The M.O. shelled blended and deoiled extracts were used. The results are shown in Fig. No to There exists an optimal rapid mixing velocity gradient of 329 s -1 (120 RPM) at 1 min for 50 and 150 NTU Kaolin and Bentonite clay initial turbidity. An optimal rapid mix velocity gradient for 450 NTU Bentonite and Kaolin clay turbidity is 415 s -1 (140 RPM). For all 50, 150 and 450 NTU turbid water samples, the residual turbidities at optimum rapid mix velocity gradient ranged from 9.1 to NTU. It is observed that the rapid mix velocity gradient is higher for 450 NTU initial turbidity of both Kaolin and Bentonite clay. CHAPTER 6 RESULTS 96

114 In case of Kaolin and Bentonite clay turbidities the rapid mix velocity gradients were same for M. O. shelled blended and deoiled extracts. For 50 and 150 NTU turbidity it was 329 s -1 (120 RPM) and for 450 NTU turbidity it was 415 s -1 (140 RPM). The results are in agreement with Muyibi (1995), which states that at initial turbidity of 50 NTU (low turbidity) and 225 to 750 NTU (moderate to high initial turbidity), the optimum rapid mix velocity gradient was 432 s -1 and 443 s -1 respectively. The results indicate that as initial turbidity increases the rapid mix velocity gradient also increases. Furthermore there is agreement with the work of Letterman et al. (1973) in which it was established that residual turbidity is a function of the length of rapid mix period with an optimum rapid mix period for each combination of rapid mix and dose of coagulant. The findings are in agreement with the work of Mhaisalkar et al. (1991) who found that the optimum values of rapid mix velocity gradient and time are dependent on the raw water turbidity Conclusion: Hence it can be concluded that for all coagulant extracts, 329 s -1 (120 RPM) is the optimal rapid mix velocity gradient for 50 and 150 NTU turbidity and 415 s -1 (140 RPM) for 450 NTU turbidity. It is also observed that out of the total results obtained for RMVG 75 % of times the RMVG is 329 s -1 (120 RPM). Hence it can be concluded that the optimal value of RMVG is 329 s -1 (120 RPM). This is in agreement with IS 3025 (Part 50):2001 which states 120 RPM and 1 min for rapid mixing process. CHAPTER 6 RESULTS 97

115 6.4 OPTIMIZATION OF SLOW MIXING VELOCITY GRADIENT The dose optimised in part A, the Jar / Container optimised in part B and the Rapid Mixing Velocity Gradient optimised in part C were considered in this stage. The jar optimised was Circular Baffled, which showed the better performance for removal of turbidity, and was considered to optimise the slow mix velocity gradient. The RMVG optimised was 120 RPM (329 S -1 ), which was used to perform the experiments at this stage. The experiments were performed as per IS 3025 (Part 50):2001. The slow mixing time was kept constant and the RPM was changed. The RPMs considered were 20 (22 S -1 ), 30 (40 S -1 ), 40 (65 S -1 ), 50 (90 S -1 ) The figures in the brackets indicate the corresponding Velocity Gradient of the RPM. The effect of variations in the RPM during mixing of coagulant, on turbidity removal was investigated Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Shelled Blended SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S -1 Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended 4. Dose ( Optimised in stage I ) For 50 NTU: 50 mg/l 150 NTU: 120 mg/l 450 NTU: 240 mg/l 5. Jars ( Optimised in stage II ) CB 6. Velocity Gradient ( Optimised in stage III ) 7. Variable Rapid Mix : 120 rpm (330 s -1 ), 1 min Slow Mix: 20 RPM (22 S -1 ), 30 RPM (40 S -1 ), 40 RPM (65 S -1 ), 50 RPM (90 S -1 ) As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min? 15 min 15 min CHAPTER 6 RESULTS 98

116 Table No. 6.40: Slow Mix V. G. (M.O. Shelled Blended) Bentonite 50 NTU Dosage mg/l Jar 50 CB RPM Residual Turbidity(NTU) Average Residual Turbidity (NTU) SET-I SET-II Average Table No. 6.41: Slow Mix V. G. (M.O. Shelled Blended) Bentonite 150 NTU Dosage mg/l Jar 120 CB RPM Residual Turbidity(NTU) Average Residual Turbidity (NTU) SET-I SET-II Average CHAPTER 6 RESULTS 99

117 Av. Residual Turbidity NTU Table No. 6.42: Slow Mix V. G. (M.O. Shelled Blended) Bentonite 450 NTU Dosage mg/l Jar 240 CB RPM Residual Turbidity(NTU) Average Residual Turbidity (NTU) SET-I SET-II Average Fig. No. 6.32: SMVG Shelled Blended Bentonite Clay 50 NTU 150 NTU 450 NTU RPM 20 RPM 30 RPM 40 RPM 50 From Fig. No. 6.32, it is observed that at 40 s -1 velocity gradient (30 RPM) there is minimum residual turbidity for 50 and 150 NTU initial turbidity. But for 450 NTU initial turbidity the optimal velocity gradient is 65 s -1 (40 rpm). CHAPTER 6 RESULTS 100

118 6.4.2 Turbidity - Bentonite Clay (50,150,450 NTU) and Extract M.O. Deoiled SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S -1 Sr. No. Type Description 1. Clay Bentonite clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled Dose (Optimised in stage I) Jars (Optimised in stage II) For 50 NTU: 35 mg/l 150 NTU: 100 mg/l 450 NTU: 200 mg/l CB Velocity Gradient (Optimised in stage III) Variable Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 20 RPM (22 S -1 ), 30 RPM (40 S -1 ), 40 RPM (65 S -1 ), 50 RPM (90 S -1 ) As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min? 15 min 15 min CHAPTER 6 RESULTS 101

119 Table No. 6.43: Slow Mix V.G. (M.O. Deoiled) Bentonite 50 NTU Dosage mg/l Jar 35 CB RPM Residual Turbidity(NTU) SET-I SET-II Average Residual Turbidity (NTU) Average Table No. 6.44: Slow Mix V.G. (M.O. Deoiled) Bentonite 150 NTU Dosage mg/l Jars 100 CB RPM Residual Turbidity(NTU) SET-I SET-II Average Residual Turbidity (NTU) Average CHAPTER 6 RESULTS 102

120 Av. Residual Turbidity NTU Table No. 6.45: Slow Mix V.G. (M.O. Deoiled) Bentonite 450 NTU Dosage mg/l Jar 200 CB RPM Residual Turbidity(NTU) SET-I SET-II Average Residual Turbidity (NTU) Average Fig. No. 6.33: SMVG Deoiled Bentonite Clay 50 NTU 150 NTU 450 NTU RPM 20 RPM 30 RPM 40 RPM 50 From Fig. No. 6.33, it is observed that at 40 s -1 velocity gradient ( 30 RPM) there is minimum residual turbidity for 50, 150 NTU initial turbidity and at 40 s -1 velocity gradient (30 RPM) for 450 NTU initial turbidity. CHAPTER 6 RESULTS 103

121 6.4.3 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Shelled Blended SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S -1 Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Shelled Blended Dose ( Optimised in stage I) Jars ( Optimised in stage II) Velocity Gradient ( Optimised in stage III) For 50 NTU: 70 mg/l 150 NTU: 130 mg/l 450 NTU: 300 mg/l CB Rapid Mix : 120 rpm (330 s -1 ), 1 min Slow Mix: 7. Variable 20 RPM (22 S -1 ), 30 RPM (40 S -1 ), 40 RPM (65 S -1 ), 50 RPM (90 S -1 ) As per IS 3025 (Part 50) :2001 Initial Turb. RMVG Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min? 15 min 15 min CHAPTER 6 RESULTS 104

122 Table No. 6.46: Slow Mix V. G. (M.O. Shelled Blended) Kaolin 50 NTU Dosage (mg/l) 70 Jar CB RPM 20 Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) Table No. 6.47: Slow Mix V. G. (M.O. Shelled Blended) Kaolin 150 NTU Dosage (mg/l) Jar 130 CB RPM Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) Table No. 6.48: Slow Mix V. G. (M.O. Shelled Blended) Kaolin 450 NTU Dosage (mg/l) Jar 300 CB RPM Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) CHAPTER 6 RESULTS 105

123 Av. Residual Turbidity NTU Fig. No. 6.34: SMVG Shelled Blended Kaolin Clay 50 NTU 150 NTU 450 NTU RPM 20 RPM 30 RPM 40 RPM 50 From Fig. No. 6.34, it is observed that at 40 s -1 velocity gradient (30 RPM) there is minimum residual turbidity for 50 and 150 NTU initial turbidity. But for 450 NTU initial turbidity the optimal velocity gradient is 65 s -1 (40 rpm). CHAPTER 6 RESULTS 106

124 6.4.4 Turbidity - Kaolin Clay (50,150,450 NTU) and Extract M.O. Deoiled SMVG - 22 S -1, 40 S -1, 65 S -1, 90 S -1 Sr. No. Type Description 1. Clay Kaolin clay 2. Turbidity 50, 150,450 NTU 3. Extract M.O. Deoiled Dose ( Optimised in stage I ) Jars ( Optimised in stage II ) Velocity Gradient ( Optimised in stage I II) For 50 NTU: 50 mg/l 150 NTU: 100 mg/l 450 NTU: 200 mg/l CB Rapid Mix : 120 rpm(330 s -1 ), 1 min Slow Mix: 7. Variable 20 RPM (22 S -1 ), 30 RPM (40 S -1 ), 40 RPM (65 S -1 ), 50 RPM (90 S -1 ) Initial Turb. RMVG As per IS 3025 (Part 50) :2001 Rapid Mix. Time SMVG Slow Mix. Time Settling Time 50, 150, 450 NTU 120 rpm (330 s -1 ) 1 min? 15 min 15 min CHAPTER 6 RESULTS 107

125 Table No. 6.49: Slow Mix V. G. (M.O. Deoiled) Kaolin 50 NTU Dosage (mg/l) Jar 50 CB RPM Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) Table No. 6.50: Slow Mix V. G. (M.O. Deoiled) Kaolin 150 NTU Dosage (mg/l) Jar 100 CB RPM 20 Resi. Turb. (NTU) Set I Set II Set III T Avg. Turb. (NTU) Table No. 6.51: Slow Mix V. G. (M.O. Deoiled) Kaolin 450 NTU Dosage (mg/l) Jars 200 CB RPM 20 Resi. Turb. (NTU) Set I Set II Set III Avg. Turb. (NTU) CHAPTER 6 RESULTS 108

126 Av. Residual Turbidity NTU Fig. No. 6.35: SMVG Deoiled Kaolin Clay 50 NTU 150 NTU 450 NTU RPM 20 RPM 30 RPM 40 RPM 50 From Fig. No. 6.35, it is observed that at 40 s -1 velocity gradient (30 RPM) there is minimum residual turbidity for 50 and 150 NTU initial turbidity. But 450 NTU initial turbidity the optimal velocity gradient is 65 s -1 (40 rpm) Observations and Discussions: Optimisation of slow mix velocity gradient was carried out on water samples of Bentonite and Kaolin initial turbidity 50, 150, 450 NTU. The M.O. shelled blended and deoiled extracts were used for the same. Fig. No to 6.35 shows the results of optimisation of slow mix velocity gradient. It is observed from the experiments that there exists an optimal slow mixing velocity gradient of, 40 s -1 (30 RPM) at 15 min for 50 NTU and 150 NTU initial turbidity and 65 s -1 (40 RPM) at 15 min for 450 NTU initial turbidity.. The optimal velocity gradient, for both the extracts and 450 NTU initial Kaolin clay and Bentonite clay turbidity, was 65 s -1 (40 RPM) The results obtained are in agreement with the work on natural polyelectrolytes of Bulusu et al. (1968) who noted that disturbance of floc formation occurs if the speed of rotation is increased to 50 RPM and that above 50 RPM, redispersion of the particles of already formed floc take place. CHAPTER 6 RESULTS 109

127 The residual turbidities at optimum slow mix velocity gradient are between 9.6 and NTU. It is observed that the slow mix velocity gradient is more for 450 NTU initial turbidity of Kaolin and Bentonite clay. In case of Kaolin clay turbidities the slow mix velocity gradients are same for M. O. shelled blended and deoiled extracts. In case of Bentonite clay turbidity, the slow mix velocity gradients are same for M. O. shelled blended and deoiled extracts. For M.O. shelled blended and deoiled extracts, slow mix velocity gradients are same for 50, 150 and 450 NTU initial turbidity Conclusion Hence it can be concluded that for shelled blended and deoiled coagulant water extracts, 40 s -1 (30 RPM) is the optimal slow mixing velocity gradient for 50 and 150 NTU initial turbidity and 65 s -1 (40 RPM) for 450 NTU initial turbidity. It is also observed that out of the total results obtained for SMVG 75 % of times the SMVG is 40 s -1 (30 RPM). Hence it can be concluded that the optimal value of SMVG is 40 s -1 (30 RPM). This is in agreement with IS 3025 (Part 50) : 2001 which states slow mix velocity gradient of 40 s -1 (30 RPM) and duration of mixing of 15 min for slow mixing process. CHAPTER 6 RESULTS 110

128 CHAPTER 7 SETTLING COLUMN STUDY Chapter 7 Settling Column Study 111

129 Chapter 7 Settling Column Study Optimisation of the coagulant dose, procedure of the settling column studies, its results and conclusion is explained in this chapter. 7.1 INTRODUCTION The study was intended to identify the effect of parameters such as diameter settling columns, initial turbidity of water samples and different coagulants, on settling characteristics of flocculent suspensions. 7.2 OBJECTIVE OF THE STUDY The broad objective of this work was to study the settling characteristics and sediment removal efficiency with the help of settling column test. In this work it was decided to use alum and Moringa Oleifera as coagulants. 7.3 METHODOLOGY: The work was performed in two stages. a. Determination of optimum dose of alum and Moringa oleifera coagulant for water samples of initial turbidity 150 NTU, 450 NTU and 1000 NTU. b. Settling column study: The settling columns of diameter m and 0.30 m and height 1.2 m were used for this study. The sampling ports were provided to collect the water samples at various depths as shown in fig. No. 7.1 and EXPERIMENTATION The experimentation was conducted in Environmental Engineering laboratory of Bharati Vidyapeeth University College of Engineering, Pune. It was decided to conduct the experimentation in two stages. Chapter 7 Settling Column Study 112

130 7.4.1 Stage 1: Finding the optimum dosage: In the first stage objective was to find the optimum dose of Alum and Moringa Oleifera coagulant for 150 NTU, 450 NTU and 1000 NTU turbidity water samples. PROCEDURE: Procedure to determine optimum dose is as follows: Tap water with stock solution of kaolin clay was used to prepare turbid water samples of 150 NTU, 450 NTU and 1000 NTU. The jars were filled with 500 ml of turbid water sample. In each jar different dose of coagulant was added. All the jars were put on the Jar Test Apparatus. These jars were put for rapid mixing at 120 rpm for 1 minute for complete and effective dispersion of coagulant in the water sample. Slow mixing was continued for 20 minutes at 30 rpm, at the end of which the jars were then kept for 20 minutes for settling. The residual turbidity of supernatant was determined at the end of settling period. Relationship was established between residual turbidity and dosage of coagulant, from which optimum dose of coagulant was determined Stage 2 Settling Column Tests In this stage the water samples were filled in the two settling columns of diameters m and 0.30 m and the optimum dosage determined in the stage -1 was added in these settling columns. The test was carried out for a. no coagulant and for b. Alum and Moringa Oleifera coagulant. At constant time interval the samples were drawn from the sampling ports of settling column and their turbidity was measured. PROCEDURE Two settling columns of depth 1.2 m and diameter m and 0.30 m, with sampling ports provided at a depth of 0.1 m, 0.3 m, 0.5 m, 0.7 m, 0.9 m, 1.1 m were used. The required turbidity sample was prepared and poured into the settling column and mixed properly with stirrer. Chapter 7 Settling Column Study 113

131 The samples were drawn from six sampling ports and the initial turbidity of each sample was determined. The average turbidity of the sample in settling column was calculated from these six readings. This average turbidity was called as initial turbidity. The optimised dose (from Stage 1) of the coagulant was added into the settling column and rapid (120 rpm, 1 min.) and slow mixing (30 rpm, 20 min.) was done. After the regular time interval of 20, 40, 60, 80, 100, 120, 140, 160, & 180 minutes, samples were withdrawn from six sampling ports and the residual turbidity was measured. Then the percent removal of turbidity was computed. The relationship between sampling depth and percent removal of turbidity was established. The said relationship plotted on figure is used to find overall efficiency of turbidity removal, detention time and further data analysis was. Analysis of settling column data The measured turbidities of each sample from each sampling port at constant time interval tabulated in the stage - 2 were used for finding the percentage removal of turbidity from their initial values. From this percentage removal efficiency of each sampling port, the overall percentage removal efficiency was computed. Then the relationship between time and overall percentage turbidity removal efficiency was established, which was used to compare the settling characteristics of floc formed due to alum and M.O. coagulants. Chapter 7 Settling Column Study 114

132 PROCEDURE 1. The percentage removal of turbidity was determined from their initial turbidity readings. These results were tabulated as follows Table No. 7.1: Percentage removal of turbidity Depth in m Duration in min % Percentage removal of turbidity samples The overall percentage removal of turbidity was calculated for each time interval. These overall percentage removal of turbidity readings were tabulated. The relationship between time and overall percent removal efficiency of turbidity was established for different initial turbidity values, different diameter of settling column and different coagulants. Chapter 7 Settling Column Study 115

133 Residual turbidity NTU 7.5 RESULTS: Optimum Dose: The optimum dose of coagulants for initial Turbidity 150NTU, 450 NTU, 1000 NTU, is given in Table No. 7.2 Table No. 7.2: Results of Dose optimisation M. O. Initial Turbidity in NTU Alum Initial Turbidity in NTU Sr Dose Dose No. mg/l Average Residual Turbidity mg/l Average Residual Turbidity Optimisation of Dose Sr. No. Turbidity NTU Alum M. O mg/l 125 mg/l mg/l 200 mg/l mg/l 350 mg/l Fig No.7.1: Alum Dose vs Residual Turbidity 150 NTU 450 NTU 1000 NTU Doses of Alum in mg/l Chapter 7 Settling Column Study 116

134 Residual turbidity NTU Fig No.7.2: M.O. Dose vs Residual Turbidity NTU 450 NTU 1000 NTU Doses of M.O. in mg/l From the Fig. No. 7.1 for Alum coagulant, it is observed that the optimum dosage of the coagulant required for the initial turbidity 150 NTU is 50 mg/l. The residual turbidity observed for this optimum dose was lowest. Further addition of alum beyond 50 mg/l showed increase in the residual turbidity. The large dosage, which eventually leads to overdosing, results in the saturation of the polymer bridge sites. This in turn gives rise to the restabilization of destabilized particles resulting in the higher residual turbidity. Then for 450 NTU initial turbidity the optimum Alum dose was 100 mg/l and for 1000 NTU initial turbidity 200 mg/l. From Fig. No.7.2 for Moringa Oleifera coagulant, the optimum dose of the Moringa Oleifera for initial turbidity 150 NTU, 450 NTU and 1000 NTU are 125 mg/l, 200 mg/l and 350 mg/l respectively. Chapter 7 Settling Column Study 117

135 Settling column Test: Settling column analysis was carried out using optimum dosage of coagulants. The samples were collected from the sampling ports at time intervals of 20, 40, 60, 80, 100, 120, 140, 160 and 180 min. The residual turbidity at these sampling ports recorded. From these reading and initial turbidity, the percent removal of turbidity was determined. This percent removal of turbidity readings were tabulated (Table No. 7.3 to 7.10). The overall percentage removal of turbidity was calculated for each time interval. These overall percentage removal of turbidity readings were tabulated in Table No to The relationship between time and overall percent removal efficiency of turbidity was established (Fig.7.3to7.8) for different initial turbidity values, different diameter of settling column and different coagulants. Coagulant - Alum Table No. 7.3: Settling column results Dia. = 18.5 cm Turbidity NTU Dose - 50 mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Coagulant - Moringa Oleifera Table No. 7.4: Settling column results Dia. = 18.5 cm Turbidity NTU Dose mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Chapter 7 Settling Column Study 118

136 Coagulant - Alum Table No. 7.5: Settling column results Dia. = 30 cm Turbidity NTU Dose - 50 mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Coagulant - Moringa Oleifera Table No. 7.6: Settling column results Dia. = 30 cm Turbidity NTU Dose mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Coagulant - Alum Table No. 7.7: Settling column results Dia. = 18.5 cm Turbidity NTU Dose mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Chapter 7 Settling Column Study 119

137 Coagulant - Moringa Oleifera Table No. 7.8: Settling column results Dia. = 18.5 cm Turbidity NTU Dose mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Coagulant - Alum Table No. 7.9: Settling column results Dia. = 30 cm Turbidity NTU Dose mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Coagulant - Moringa Oleifera Table No. 7.10: Settling column results Dia. = 30 cm Turbidity NTU Dose mg/l Percentage removal of Turbidity Time (min) Depth (m) Average Chapter 7 Settling Column Study 120

138 Table No. 7.11: Settling Column Results (150 NTU) Diameter of settling column Sampling Time in min. Dose In mg/l Without Coagulant Overall % removal efficiency Dose in mg/l Alum % removal efficiency Dose in mg/l Moringa Oleifera Overall % removal efficiency cm cm Chapter 7 Settling Column Study 121

139 Table No.7.12: Settling Column Results (450 NTU) Diameter of settling column Sampling Time in min. 20 Dose In mg/l Without Coagulant Overall % removal efficiency Dose in mg/l Alum % removal efficiency Dose in mg/l Moringa Oleifera Overall % removal efficiency cm cm Chapter 7 Settling Column Study 122

140 Table No : Settling Column Results (1000 NTU) Diameter of settling column Sampling Time in min. 20 Dose In mg/l Without Coagulant Overall % removal efficiency Dose in mg/l Alum Overall % removal efficiency Dose in mg/l Moringa Oleifera Overall % removal efficiency cm cm Chapter 7 Settling Column Study 123

141 % Overall Efficiency % Overall Efficiency Fig. No. 7.3: Time Vs % Overall Efficiency Turbidity 150 NTU & Dia cm Coagulant - No/ Without Coagulant Coaglant - Alum Coagulant - Moringa Oleifera Time in min Fig No. 7.4: Time Vs % Overall Efficiency Turbidity 150 NTU & Dia. 30 cm Coagulnt - No Coagulnt - Alum Coagulnt - Moringa Oleifera Time in min Chapter 7 Settling Column Study 124

142 % Overall Efficiency % Overall Efficiency Fig. No. 7.5: Time Vs % Overall Efficiency Turbidity 450 NTU & Dia cm Coagulant - No Coagulant - Alum Coagulant - Moringa Oleifera Time in min Fig. No. 7.6: Time Vs % Overall Efficiency Turbidity 450 NTU & Dia. 30 cm Without Coagulant Coagulant- Alum Coagulant- Moringa Oleifera Time in min Chapter 7 Settling Column Study 125

143 % Overall Efficiency % Overall Efficiency Fig. No. 7.7: Time Vs % Overall Efficiency Turbidity 1000 NTU & Dia cm Withput Coagulant Coagulant - Alum Coagulant -Moringa Oleifera Time in min Fig. No. 7.8: Time Vs % Overall Efficiency Turbidity 1000 NTU & Dia. 30 cm Without Coagulant Coagulant - Alum-Lime Coagulant - Moringa Oleifera Time in min 7.6 OBSERVATIONS: From Fig. No. 7.3 to 7.8, it is observed that for no coagulant and with all the coagulants as the initial turbidity increases the percentage removal efficiency also increases. It is also observed that for the larger diameter, the removal efficiency is more as compared to the smaller diameter of the settling column. This is because the wall effects are more pronounced in smaller diameter columns. Chapter 7 Settling Column Study 126

144 The maximum turbidity removal efficiency obtained for no coagulant at 180 minutes detention time in the settling column. For 150 NTU, 450 NTU and 1000 NTU initial turbidity, the removal efficiencies of 30 cm diameter settling column are %, % and % respectively. The maximum turbidity removal efficiency obtained for Alum coagulant at 180 minutes detention time in the settling column. For 150 NTU, 450 NTU and 1000 NTU initial turbidity, the removal efficiency of 30 cm diameter settling column are as %, % and % respectively. The maximum turbidity removal efficiency obtained for M. O. coagulant at 180 minutes detention time in the settling column. For 150 NTU, 450 NTU and 1000 NTU initial turbidity, the removal efficiency of 30 cm diameter settling column are as %, % and % respectively. From the comparison of overall removal efficiency at constant time interval of all these coagulants it is observed that the maximum turbidity removal efficiency is obtained by Alum followed by M.O. and finally it is the least for no coagulant. 7.7 CONCLUSION The Alum and M. O. coagulant showed very marginal difference in the turbidity removal efficiency for small and large diameter settling column and also for different turbidity concentrations. The settling properties of the floc formed due to Alum and M.O. are almost similar. Hence Moringa Oleifera can be considered as an alternative solution to alum coagulant. Chapter 7 Settling Column Study 127

145 Fig. No. 7.1: Settling columns Fig. No. 7.2: Sketch of Settling Column Chapter 7 Settling Column Study 128