Author : Rinku Walia, Pradeep Kumar and Indu Mehrotra

In India and other developing countries, since early nineties, upflow anaerobic sludge blanket (UASB) reactors have come up in a big way for the treatment of sewage Sequence adopted: screens- grit chambers- UASB reactors followed by one-day detention pond (PP). Performance of PPs located at five STPs (27-70 ML/d) was evaluated over a period of one year from July 2004 to July 2005.The installation of these non-algal ponds reduced land requirement, but from treatment point of view it at best offered only removal of solids washed out of the UASB reactor. Total coliform count in the effluent from polishing ponds ranged from 10 6 to 10 9 MPN /100 mL is more than the maximum permissible limit of 10,000 MPN/100 mL (Foundation for Greentech Environmental Systems 2004). Suspended solids (SS) concentration in the effluent from polishing ponds ranged from 100 to140 mg/L which again exceeds the limit of Indian discharge standards. Effluent are devoid of oxygen and in reducing state (ORP: – 90 to -145) indicating immediate demand of O2. The nutrient level is also high.

Keywords: Polishing ponds; Chemical oxygen demand; Wastewater; Anaerobic treatment

Article published in International Journal of Current  Engineering  and Technology, Vol.4,No.3 (June- 2014)