A Framework for the Removal of Bacterial Contamination from UASBR Effluent

Sewage in India is treated to primary or secondary level of treatment. Recently, standards for the indicator micro-organisms for the effluents from the sewage treatment plants (STPs) have been proposed. Selection of appropriate technology for the augmentation of the existing STPs is under consideration. Many of these plants are based on the Upflow Anaerobic Sludge Blanket Reactor (UASBR) technology. The fecal coliform count in UASBR effluent was found to be of the order of log cycles of six, which exceeds the WHO guidelines by an order of 3. The evaluation study of pilot plants had been carried out at two different UASBR based sewage treatment plants in India. One of the pilot plants is based on chlorination (2 MLD), and other is based on fixed film aerobic process (1 MLD, biotower). Evaluation study consisted of onsite monitoring of the COD and fecal coliform over a period of 3 months. Samples were collected from the inlet and outlet of the plant. It is contemplated to select an appropriate disinfection technology for the treatment of the effluents from UASBR based sewage treatment plants so as to meet the biological quality standards. The results show that the fecal coliform removal is up to 98.2 and 100% for biotower and chlorination respectively. Removal of COD has also been determined.