TREATMENT OF SUGAR PROCESS WASTE WATER AND BIOGAS PRODUCTION USING ALGAL BIOMASS

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1 TREATMENT OF SUGAR PROCESS WASTE WATER AND BIOGAS PRODUCTION USING ALGAL BIOMASS COLLEGE : BASAVESHWAR ENGINEERING COLLEGE (AUTONOMOUS), BAGALKOT DEPARTMENT : ENVIRONMENTAL ENGINEERING AND BIOTECHNOLOGY GUIDE : PROF. DR. BHARATI S METI STUDENT : SAILAJA. B Key words: Waste water, Chlorella, Anaerobic digestion, Co-digestion, Sludge. Introduction: Wastewater is a general term used to represent the water with poor quality that contains more amounts of pollutants and microbes. The wastewater discharged into the water bodies are hazardous to environment and cause Eutrophication.To remove these nutrients, several processes are used, but the disadvantages of this type of treatment are high cost and increased sludge production. As an alternative to the conventional treatment methods, microalgae are suggested to remove the nutrients from wastewater. An attempt to treatment municipal waste water with chlorella sp was made by (Yecong Li et al 2011, Changfu Wang et al 2012) in this study there was a reduction of TN from 58-89%,TP 80-90%, and COD by 90.8%. Liang wang et al 2010 has also used municipal waste water in his study and treated with chlorella sp he found that ammonia was reduced by 82.4%, Nitrate 62.5%, TN 90.6% and COD by 83%. Luz T. Valderrama et al 2012 studied on Treatment of recalcitrant wastewater using the microalgae Chlorella vulgaris and the macrophyte Lemna minuscule, the waste water was diluted to 10%, and there was a reduction of ammonium ions by 71.6%, phosphorus 28%, COD by 61%. Microalgae are eukaryotic microscopic aquatic plants that carry out the same process and mechanism of photosynthesis as higher plants in converting sunlight, H 2 O + CO 2 into biomass + O 2. Algae provide an efficient way to consume nutrients and provide oxygen needed for the growth of aerobic bacteria. Also, through the process of algal wastewater treatment very large amounts of algal biomass can be grown. In addition, microalgae are rich in lipids, starch and protein, which can be utilized as a non-food-based feedstock for biofuels (mainly in the form of biodiesel, bio ethanol and biogas).co digestion of sewage sludge with micro algae has studied by (Chen 1987, Guleke et al 1987, Ceechit et al 1996) in all this study it is concluded that there was an increase in bio gas and methane content when compared to digestion of algae alone. Since the demand for biogas is continuously growing in the society and the biogas substrate, for example food waste, may soon become limited.one way to enhance bio gas is co-digestion of sludge with algae. Objectives: 1) To treat sugar process waste water using algal biomass. 2) To study the reduction of BOD, COD, TN and Phosphorus in wastewater. 3) To study co-digestion of algal biomass and sludge for biogas production. Methodology: Inoculum development: Algae pure culture namely Chlorella sp is collected from Department of Biotechnology, BEC Bagalkot. Mass culturing of algae is carried out in Bolds Basal Media (BBM). Collection of Wastewaters and undigested sludge: Waste water (sugar process waste water) Sample1=laggon1, Sample2=lagoon2, Sample3=Digestor outlet for algae growth and undigested sludge for anaerobic digestion were collected from Godavari Biorefinaries ltd, Sameerwadi. Inoculation of Algal cells In Waste Water (Effluent): Waste water samples are sterilized and diluted to different concentrations using tap water (25%, 50%, 75% and 100%) to check the growth of algal cells. Depending on growth of algae in above said dilution 40ml of algal suspension (9 by wet basis) was inoculated to each sample which has a working volume of 5L.The ph for all the samples was maintained at 6.8. The treatment was carried out as an open system.

2 Initial Final Initial Final Initial Final a b c Fig 1: Algal growth in the initial and final samples a) sample1, b) sample2, c) sample3. Analysis of treated waste water: Algal growth in the waste water was determined using 3 different methods 1) Cell count using Hemocytometer. 2) Optical density at 680nm and 3) Centrifugation. Samples for nutrient reduction analysis was collected at regular intervals during the treatment.the collected sample were centrifuged at 10,000 rpm for 10 min and the supernatant was collected for analyses of COD, BOD,TN and phosphorus. The measurements of BOD, COD, and phosphorus were performed using standard method for examination of water and waste water, APHA Estimation of nitrogen was carried out using Kjeldahl Distillation Method (UHS,Bagalkot) Fig 2: Algal Cells count by Hemocytometer Harvesting of Algal Biomass and co digestion of Harvested Algal Biomass: Algal biomass was harvested using cross flow filtration (TFF) followed by centrifugation. Fig 3: Harvested algal biomass Fig 4: Biogas production set up The harvested algal biomass along with sludge was co-digested for bio gas production and analyzed quantitatively by water displacement method and qualitatively using portable methane detector (Fig 5). Set up of small reactor with working volume of 100ml was designed for biogas studies.three sets of experiments were conducted, first set was control with sludge alone the next two sets were varied with algal concentration 20% algae and 40% algae (1g and 2g by dry weight).the ph for all the digestion samples were maintained at , VS and TS of both algae and sludge was estimated according to standard methods for examination of water and waste water APHA 1998.Carbohydrate was estimated using Anthrone method, protein by Lowry s method and lipid by colorimetric quantification.

3 Fig5: Portable methane detector Results: Reduction of nutrients, COD and BOD after treatment: BOD, COD, TN and phosphorus reduction were studied in all 3 different waste water samples after 12 days of inoculation (Table1).Sample 1 showed the maximum TN and phosphorus reduction, sample 3 showed the maximum reduction of BOD and COD. Table 1: Reduction of Nutrients, BOD and COD in 3 different Waste Water % of Reduction (After 12 days) BOD(mg/L) COD(mg/L) TN(mg/L) Phosphorus (mg/l) Sample Sample Sample Algal Growth Studies: Growth of algae was determined by the following three methods. Were as cell count using Hemocytometer found to be suitable method in the present study (Chlorella). Growth pattern of chlorella studied in these 3 samples and compared it with BBM media.growth was started on 2 nd day in BBM media and Continued upto 18 days. Where chlorella inoculated in waste water samples showed better growth upto 10 th and reached the stationary phase. 85x10 5 cells/ml biomass obtained in sample3 which was highest compared to sample2 (77x10 5 cells/ml) and sample3 (60x10 5 cells/ml). Graph 2: Growth determination by centrifugation Graph 3: Growth determination by Optical density Graph 3: Algal Cells count by Hemocytometer Graph 4: BBM media

4 Co digestion of harvested algal biomass: Graph4 represents the bio gas yield there was a increase in bio gas with increase in algal concentration when compared to digestion of sludge alone(control).methane content was also increase by 6% and 8% when algal concentration increased Graph5: Bio gas yield after 14 days Table2: Methane content after 14 days Bio gas yield ( ml/) No of days control 20% algae 40% algae Control (sludge alone) Methane(CH 4 ) content in % 20%algae+ 80% sludge 40% algae+60% sludge Proximate and ultimate analysis: Algae and sludge are characterized separately using standard methods. Total solids was more in algae compared to sludge were as Volatile solids was found more in sludge compared to algae (Table 3).Protein, carbohydrate and lipid content were also estimated, carbohydrate, protein and lipid content is found more in algae when compared to sludge (Table 3). Table3: Characteristics of algae and sludge Sample Total solids mg/l Volatile solids mg/l Protein Carbohydrate Lipid Algae Sludge Conclusion: Algae can be grown in sugar process effluent where COD, BOD, TN and phosphorus can be reduced. The effluent from lagoon1,lagoon 2 (without dilution) could not support algal growth may be due to high level of COD, at dilution with 25% effluent(75% water) algal growth may be obtained, where as in sample3 (without dilution) supported the growth of algae may be due to lower level of COD. The growth rate of algae increased with decreasing concentration of COD level. Algal based waste water treatment reduced COD up to 85% BOD up to 88%, TN by 64.28% phosphorus by 61% within 12 days In the present study co-digestion of microalgae and sludge increased 58.63% of bio gas and 8% methane content when compared to sludge alone. Hence microalgae like chlorella sp may be inoculated in

5 sample3 directly and with dilution in sample 1 and 2 to reduce the load simultaneously this biomass obtained may be used to the bio gas unit to enhance the methane. Scope of Further Work: 1) Optimization of biogas (methane) production using microalgae. 2) Detail ultimate and proximate analysis during the algal growth. 3) Treatment of different waste water using micro algae.