Efficiency evaluation of three fluidised aerobic bioreactor based sewage treatment plants in Kashmir Valley

Abstract

The present investigation was conducted to monitor the physico-chemical characteristics and microbial load of sewage treatment plants (STPs) around the Dal Lake. The results show highly significant (P<0.001) reduction in some physico-chemical features and in microbial load at outlet of each STP. Order of reduction in all the STPs was found to be biochemical oxygen demand (BOD) > chemical oxygen demand (COD) > conductivity and fecal coliform (FC) > total coliform (TCC) > fecal streptococcus (FS) in the case of physico-chemical parameters and microbial characteristics, respectively. The overall performance of the wastewater treatment plant effectively removed TCC, FC and FS as follows, 52, 65 and 45%, respectively. Raw sewage showed insignificant (p>0.05) variation in some of the physico-chemical features and microbial load between the three STPs. Similarly, effluent also showed insignificant (p>0.05) variation in some of the physico-chemical features and microbial load, except conductivity which showed significant difference between the three STPs. Efficiency rates showed significant (p<0.05) differences in COD between the three STPs. The removal efficiency rate was not dependent on the type of STP and the year. It can be concluded from the study that the majority of physico-chemical features and microbial load exceeded the permissible limit as per Indian national standards. Therefore as per the results, it is suggested that the effluent should be pretreated before disposing into the environment. In addition, there is an urgent need to improve their efficiency rate by including advanced tertiary treatment processes such as rapid sand filtration, UV disinfection, chlorination, effluent polishing, construction of artificial wetlands, etc.

Keywords: Microbial load, sewage treatment plants, contamination load, efficiency rate

African Journal of Biotechnology Vol. 12(17), pp. 2224-2233,