GENERATION, CHARACTERISTICS AND TREATMENT OF MUNICIPAL WASTEWATER IN MADURAI CITY

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1 International Journal of Civil Engineering and Technology (IJCIET) Volume 6, Issue 9, Sep 2015, pp , Article ID: IJCIET_06_09_006 Available online at ISSN Print: and ISSN Online: IAEME Publication GENERATION, CHARACTERISTICS AND TREATMENT OF MUNICIPAL WASTEWATER IN MADURAI CITY Rajendran S.M Research Scholar, Department of Civil Engineering, Karpagam University, Coimbatore, TN, India Dr. Sekaran V Former Principal, Raja Engineering College, Madurai, TN, India ABSTRACT Assessment of characteristics of raw sewage and treated effluent from the sewage treatment plant (Sequential Batch Reactor), for Madurai city from January 2014 to December 2014 was studied. The daily average sewage generation over the year 2014 is MLD. The raw sewage BOD was in the order of 200 to 300 and the characteristics indicate its domestic nature. The Characteristics of treated effluent were well within the Central Pollution Control Board standards. BOD and COD removal efficiency is more than 95 % and is also consistent over the study period. Scope for improving the efficiency of oil and grease still remains. Key words: Wastewater generation, Characteristics and treatment, Madurai city. Cite this Article: Rajendran S.M and Dr. Sekaran. Generation, Characteristics and Treatment of Municipal Wastewater in Madurai City. International Journal of Civil Engineering and Technology, 6(9), 2015, pp INTRODUCTION 1.1 General Madurai city, known for Tamil language development, is one among the ten metropolitan cities in Tamil Nadu. Having located at almost in the southern part of the state, it is the city for education and business. City covers an area of square kilo metre. Climate prevailing is arid to semi arid. Rainfall is occasional. In addition to urbanization, more and more adjacent areas are merged with the city corporation limit. The location is given in figure editor@iaeme.com

2 Wastewater generation, MLD Generation, Characteristics And Treatment of Municipal Wastewater In Madurai City Figure 1 Location of Madurai city The forecast indicates that the population during the year 2044 is more than 30 lakh. It is almost double the 2011 census population. the present water supply level is more than LPCD ( litres per capita per day ) and it is planned to increase to 135 LPCD. Vaigai river is the major source for the city's drinking water demand. Surrounding area of the city is an agricultural area. 1.2 Wastewater generation calculation Wastewater quantity generation is generally assumed as 80 % of quantity of water supplied for drinking purpose. Assuming the per capita rate as litres per head per day, the quantity of wastewater generation is shown in figure Arithmetic increase Incremental increase Geometric increase Line of best fit Figure 2 Wastewater generation in Madurai - present and future 59 editor@iaeme.com

3 Rajendran S.M and Dr. Sekaran Forecast indicates a wastewater quantity of around 160 MLD and 300 MLD at present and in 2014 and 2044 respectively. Almost a constant quantity of wastewater can be expected from the city as the drinking water supply has to be consistent. 1.3 Sewage Treatment Plant (STP) Madurai city has 2 numbers of sewage treatment plants located one at Avaniyapuran and the another at Sakkimangalam. The former has 125 Million litres per day (MLD) capacity and the latter s capacity is MLD totaling to MLD. Among various sewage treatment technologies available ( Oxidation ditch, Activated sludge process, extended aeration(asp), Up flow anaerobic sludge blanket (UASB), fluidized aerobic bio reactor(fab), moving bed bio reactor (MBBR), sequential batch reactor (SBR), membrane bio reactor (MBR), waste stabilisation ponds, etc, the sewage treatment plant of Madurai city employs SBR technology ( otherwise called as C-Tech basins) with necessary primary treatment unit (screen, grit removal) and disinfection with sludge handling arrangement due to the following advantages. Aerial view of the sewage treatment plant at Avaniyapuram is shown in photo 1. Less area to install the plant Good efficiency in treatment, like reducing BOD, COD, TSS, etc. Biological nutrient control for total nitrogen No need of secondary treatment. Reducing the treatment time. Total working in Automation so less manpower. Total process take in aerobic method no need of anaerobic no danger. Reduced energy consumption Biological phosphorus control. Photo 1 Aerial view of Sewage treatment plant with irrigation tank at Madurai 1.4 sewage farms Wastewater reuse is not new for the Madurai city corporation. It has two sewage farms. One is located at Avaniyapuram with an area extend of 385 acres, which is utilized for both solid waste dumping yard and sewage farm. Guinea grass is grown in 145 acres and the rest is used for solid waste management. Sakkimangalam sewage 60 editor@iaeme.com

4 Generation, Characteristics And Treatment of Municipal Wastewater In Madurai City farm incorporates 180 acres of land. Photo 2 shows the guinea grass grown in the farm. Annual revenue earned from the sewage farm on selling fodder is about Rs lakh. Photo 2 Sewage farm with Guinea grass (fodder crop) at Madurai After wetting the farm, reclaimed water flows into the nearby irrigation tank and stored. These tanks are dry in most of the months in a year. they receive flow only during north-east monsoon i.e during October and November. 2. MATERIALS AND METHODS Raw sewage and the treated effluent samples were collected daily during January to December 2014 for testing the ph, temperature, total suspended solids (TSS), Biological oxygen demand (BOD), chemical oxygen demand (COD), dissolved oxygen (DO), Oil and grease ( O&G) and were analysed as per the standard methods for water and wastewater analysis. The efficiency of treatment of each parameter was determined using the formula given below. (Value of raw sewage- value of treated effluent) Efficiency = X (1) Value of raw sewage Statistical parameters viz: maximum, minimum, mean and range, were also determined. 3. RESULTS AND DISCUSSION The results of daily sewage generation and characteristics of raw sewage with the treated effluent parameters are presented below. 3.1 Sewage generation The daily actual sewage generation in Madurai varies from MLD to MLD with the range of MLD due to varied reasons. The annual sewage generation is found as MLD. Though the sewage generation is taken as 80% of water supply, 61 editor@iaeme.com

5 Rajendran S.M and Dr. Sekaran practically the quantity reaching at STP is found lesser than the calculation based on the above guideline. The per capita daily water supply is also varying. It is observed that there is a time lag between the sewage generation at households and reaching the STP. It infers that some portion of sewage is always in travel. There are some storage in main pumping station, sub pumping stations and lift stations. Out 365 days, STP was in operation due power shut down in pumping locations and repair and servicing etc. In Perambalur underground sewerage scheme (UGSS), the daily sewage generation is around 2.0 MLD against the calculated daily quantity of 4.20 MLD. 3.2 Characteristics of raw sewage and treated effluent The mean, maximum, minimum and range value of ph, temperature, DO, TSS, COD, BOD and oil and grease for the raw sewage and treated effluent from the STP are given in table 1 and table 2 respectively. Sl.No Parameter ph Table 1 Characteristics of Raw sewage during the year 2014 T ( C) DO, TSS COD BOD OIL& GREASE 1 Mean Max Minimum Range It is observed that the raw sewage ph is fluctuating from the maximum of 7.28 to a minimum of 6.2. Almost the raw sewage is acidic. The temperature of sewage is found to follow the atmospheric temperature. During winter it was 22.5 C with the highest temperature of 33 C. The dissolved oxygen content was zero in the raw sewage from January 1 to 31 December TSS recorded a maximum of 421 with the minimum of 296. It is inferred that the TSS is less during winter and rainy season. It may be due to dilution. The COD value in the raw sewage fluctuates between 300 and 190. The maximum BOD value in raw sewage was found as 300 with the lowest value of 190. In general, the BOD value in the domestic sewage shall be in the order of 200 to 300. The raw sewage characteristics indicate that sewage is of domestic origin only. No industrial effluent is coming in the sewage. Oil and Grease is present in the level of 6 to 12. Table 2 Characteristics of treated effluent from STP during the year Sl.No Parameter ph TEMP ( C) DO, TSS COD BOD OIL& GREASE 1 Mean Max Minimum Range It observed from the table 2 that the ph of the treated effluent is above 7.0. The acidic raw sewage after treatment becomes slightly alkaline. As aerobic treatment process has been done, gas transfer taking place during treatment process enhances the ph value of treated effluent. The temperature of effluent after treatment increases slightly over the raw sewage. It may be the fact that during the digestion of organic 62 editor@iaeme.com

6 ph Generation, Characteristics And Treatment of Municipal Wastewater In Madurai City compounds a little bit of temperature is common. Fluctuation is similar as in raw sewage. The dissolved oxygen level has considerably increased from zero in the raw sewage to about 2 to 8 in the treated effluent due aeration process in the treatment system. TSS in the treated effluent is found in the order of 3 to 10. TSS in the treated effluent is well within the stipulated value set by the pollution control board,. Maximum COD value noticed in the treated effluent is 82 with the range of 70. COD is always less 250, the standard value for the discharge. BOD value in treated effluent is observed in between 4 and 14 mg/ with the variation of 10. The maximum value set for the BOD for the discharge is 30. Oil and grease value in the treated effluent records at the average of 1.04 against the raw sewage mean of 9.3. The oil and grease value can be still brought down if efficient oil and grease mechanism is employed. The method adopted in the sewage treatment system is aerobic- sequential batch reactor. Complete filling, aeration, settling and decanting are done in a basin. Entire system is operated by automatic control arrangements. 3.3 Mean monthly variation of raw and treated effluent ph Monthly mean ph value of raw sewage and treated effluent is presented in figure 3. It is found that the increase in ph after treatment. A comparison the raw sewage ph in various cities in India with Madurai in figure 4 and it infers that ph in south Indian cities ( Bangalore, Madurai, Perambalur) show raw sewage ph value less than 7. It may be due to food habit and nature of the sewerage system ie either domestic or combined with industrial effluent Raw sewage 6.00 Figure 3. Monthly mean ph of raw sewage and treated effluent 63 editor@iaeme.com

7 TEMP 0 C ph Rajendran S.M and Dr. Sekaran Figure 4. ph of sewage in various cities in India Temperature Mean monthly variation of temperature of raw sewage and treated effluent during January to December 2014 is shown in figure 5. It is clear that treated effluent temperature is higher than the raw sewage temperature for the reason stated elsewhere. December and January are winter months and hence the temperature of both raw and treated effluent is the lowest. Summer and pre monsoon months, May to August, temperature is high in lieu of high atmospheric temperature Raw sewage Treated effluent Figure 5. Monthly mean Temperature of raw sewage and treated effluent Dissolved oxygen (DO) Monthly mean value of dissolved oxygen (DO) values in raw sewage and treated effluent is shown in figure 6 for easy understanding. It shows that the treatment process certainly increases the DO considerably editor@iaeme.com

8 TSS, DO, Generation, Characteristics And Treatment of Municipal Wastewater In Madurai City Raw sewage Treated effluent Figure 6.Monthly mean DO of raw sewage and treated effluent Total Suspended Solids (TSS) Monthly mean value of TSS of raw sewage and treated effluent with the standard value stipulated by Pollution Control Board is depicted in figure 7. It infers that treated effluent has TSS value well below the standard. Figure 8 shows the efficiency of TSS removal in the STP. Good efficiency is found Raw sewage Treated effluent CPCB standard Figure 7. Monthly mean TSS value of raw sewage and treated effluent with CPCB standard 65 editor@iaeme.com

9 COD, Efficiency, % Rajendran S.M and Dr. Sekaran Figure 8. Efficiency of TSS removal in STP Chemical oxygen demand (COD) Figure 9 depicts the mean monthly COD value of raw sewage, treated effluent and standard value for the period January to December The efficiency of COD removal in the STP is also presented in figure 10. It is observed that the sequential batch reactor has high COD removal efficiency. The difference in efficiency over the months is very marginal and it shows its consistency in removal Raw sewage Treated effluent CPCB standard Figure 9. Monthly mean COD value of raw sewage and treated effluent 66 editor@iaeme.com

10 BOD, Efficiency, % Generation, Characteristics And Treatment of Municipal Wastewater In Madurai City Figure 10. Efficienct of COD removal in STP Biological oxygen demand (BOD) The BOD of raw sewage and the treated effluent over the one year period with the standard value is presented in figure 11. The figure indicates that the BOD value is consistently lower than the standard value, 30. It is observed from the efficiency curve (figure 12) that it is above 95% raw sewage Treated effluent Pollution standard 50 0 Figure 11. Monthly mean value BOD of raw sewage and treated effluent with standard 67 editor@iaeme.com

11 OIL & GREASE, Efficiency, % Rajendran S.M and Dr. Sekaran Figure 12. Efficiency of BOD removal in STP Oil & Grease Figure 13 and 14 show the value of oil and grease present in the raw sewage and treated effluent and efficiency. The efficiency of oil and grease removal is in the order of 85% to 90%. Comparing with the BOD, COD and TSS removal efficiency, oil and grease removal efficiency is lesser. There is a scope for increasing the same and may be done Raw sewage Treated effluent Figure 13. Monthly mean Oil & Grease value of raw sewage and treated effluent 68 editor@iaeme.com

12 Efficiency,% Generation, Characteristics And Treatment of Municipal Wastewater In Madurai City Figure 14. Efficiency of Oil and Gas removal in STP 3.4 Comparison of sewage characteristics BOD, COD and TSS values in the sewage of various cities in India is shown in figure 15. Variation in the sewage characteristics is observed. BOD value at Bhilai is 21. Chandigarh records the highest BOD value at 236 among the compared cities. The BOD value at Madurai is 228. TSS is lesser than BOD value at Bhilai and Nasik. In all other places TSS value is found higher than BOD. Generally, higher BOD (more than 300 ) is observed when industrial effluent is combined with industrial effluent. Figure 15 infers that all the sewages are domestic in nature BOD COD TSS Figure 15. Characteristics sewage in various cities in India All values are in 69 editor@iaeme.com

13 Rajendran S.M and Dr. Sekaran 4. CONCLUSION Assessment of sewage generation and results of characteristics analysis of raw sewage and treated effluent from January to December 2014 results draw the following conclusions: Fluctuation in quantity of sewage generation due to per capita water supply, power supply position, repair and renewals of machineries, The present quantity of sewage generation is about half of the design quantity. Sewage generated is of domestic in nature. BOD is in the range 200 to 300. Efficiency of BOD and COD removal in sewage treatment plant based on sequential batch reactor is more than 95%. Sewage treatment efficiency is consistent, Oil and grease removal efficiency is still to be increased, Sewage characteristics vary across the country with respect to food habits. REFERENCES [1] Mariappan, P, Wastewater Management in a dwelling house- A case study, International Journal of Civil Engineering and Technology, 3(2), July-December 2012, PP: [2] Javier Mateo Sagasta and Prit Salian, Global database on municipal wastewater production, Collection, treatment, discharge and direct use in agriculture, Aquastat, FAO [3] Tamil Nadu Water Supply and Drainage Board Web site. [4] Bhamoriya, V, 2002, Wastewater and welfare: Pump Irrigation Economy of Periurban Vadodara, Annual Partner's meet 2002, IWMI-Tata Water Policy Program, Anand, Gujarat, India. [5] Gopal, B, et al, 1991, Land Application of Municipal Sewage for Resource Recovery: the Indian Experience, National Institute of Ecology, New Delhi, India. [6] Central Pollution Control Board, 2005, Status of Sewage Treatment in India. [7] Central Pollution Control Board, Performance evaluation of sewage treatment plants under NRCD [8] Rajendran, S. M and Dr. Sekaran, V, 2014, Municipal wastewater reuse in arid regions- scope for irrigation in Madurai city, International journal of Civil Engineering and Technology, 5(7), PP: [9] D. Jayganesh, Dr. J. Jegan and Dr. P. Mariappan, Impact of Staging Height of Service Reservoir on The Installation Cost of Water Supply Scheme - A Case Study, International journal of Civil Engineering and Technology, 4(5), PP: [10] Er. Devendra Dohare and Er. Parth Bochare, Sequential Batch Reactors: Taking Packaged Wastewater Treatment to New Heights - A Review, International journal of Civil Engineering and Technology, 5(10), PP: editor@iaeme.com