Performance Evaluation of Full Scale UASB Reactor in Treating Sewage Under Psychrophilic Conditions

Abstract

The aim of the study was to assess the performance of a full scale Upflow Anaerobic Sludge Blanket reactor (UASBR) with respect to COD removal for domestic wastewater under low temperature conditions. Tests on Temperature, pH, Alkalinity, BOD, COD, Total Solids (TS) and Volatile Solids (VS) were conducted for influent and effluent to evaluate the performance of reactor under psychrophilic conditions. Grab samples were collected once a month from sewage treatment plant (STP) located at Lalpani, Shimla, and Himachal Pradesh, India . The COD removal efficiency ranged from 13 - 42%, which was not satisfactory. The maximum removal efficiencies of BOD, Suspended Solids (SS) and VS were 36%, 82% and 67% respectively. The main reason for the unsatisfactory performance of UASB reactor was the poor operation and maintenance of the reactor. Biochemical methane potential (BMP) of domestic wastewater was determined at different substrate to biomass (F/M) ratio in order to assess the biodegradability of wastewater. BMP test was performed in batch bioassay by using the serum bottle technique and gas was collected by inserting a glass syringe in the bottle. Granular sludge from UASB reactor was used as inoculum. Specific methanogenic activity (SMA) of reactor sludge was also determined at 20ºC to evaluate the quality of sludge. The SMA test was carried out by using serum bottle technique using sodium acetate as substrate. A COD mass balance was done for BMP.