TREATMENT OF DOMESTIC SEWAGE USING UPFLOW ANAEROBIC SLUDGE BLANKET REACTOR

Due to the urbanization and growth of cities, many of the water sources in and around the cities like Chennai has dwindled. Catchments areas have been converted into houses. Lakes have dried up and individual houses are going for rainwater harvesting. Over exploitation of groundwater has resulted in seawater intrusion leading to non-reversible contamination of groundwater potential. Considering the above problem CLRI has taken up a lead role in recovery and reuse of water from its Quarters. At present CLRI is purchasing raw water to the tune of Rs. 12,000/day. Part of the water is also used for gardening. To save on the expenditure towards water cost and to show a lead path in recovery and reuse of water, CLRI is treating about 30m3 of domestic wastewater in Up flow Anaerobic Sludge Blanket (UASB) reactor for reduction of organic matter followed by waste stabilization pond for reduction of fecal coliform. An UASB has been fabricated with Fiber Reinforced Plastic (FRP) for this study. The total capacity of the reactor is 12.5m3 followed by waste stabilization pond (WSP) of 40 m3 capacity. HRT of the reactor was maintained at 10–12 hrs. The domestic wastewater had an average BOD5 of 135mg/l and COD of 373mg/l respectively. 4660% of COD, 50–60% of BOD was removed successfully. Fecal Coliform MPN/100ml was reduced from an average of 6.2 × 106 to 9.2 × 103 MPN /100ml with an average removal efficiency of 87% in WSP. The study shows production of 0.7m3 methane per day. VFA: Alkalinity ratio lies below 0.4 shows that the reactor was stabilized without any major change in pH. Two-month study shows satisfactory performance of UASB and WSP in tropical climates for the treatment of domestic wastewater. The results clearly show that treated water from waste stabilization pond can be reused. Therefore from the treatment of domestic wastewater of about 30m3/day, CLRI is decided to implement a full-scale plant to treat the total wastewater of about 200m3 in order to reuse the water for gardening and aquaculture purposes.