Performance evaluation of prevailing biological wastewater treatment systems in West Bengal, India
The present study has been undertaken to evaluate the performance of wastewater treatment systems (WWTS) in three different districts (Kolkata, Howra and Hugli) in West Bengal, India. Performance of these wastewater treatment plants are essential parameter to be monitored as the treated effluent is discharged into River Ganga which is the National River of India. The performance evaluation will also help for the better understanding of design and operating difficulties in wastewater treatment plants. The performance evaluation was done on the basis of removal efficiency of Biochemical Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Total Coliform (TC) and Fecal Coliform (FC). The performance of prevailing oxidation pond and activated sludge process type was good in terms of BOD, COD and TSS removal. Even though the removal efficiency of total and fecal coliform was high (85-98%), none of the plants meet the coliform discharge standards because of the high incoming TC and FC.