PERFORMANCE EVALUATION OF DECENTRALIZED WASTEWATER TREATMENT SYSTEMS IN NORTH INDIA

Abstract

Shortage of available water resource is a common problem in many regions of the world. One important measure to solve the problem is to use treated wastewater for non-drinking purposes. Centralized wastewater treatment and reuse often needs large investment . and sophisticated management and maintenance systems, which may be unaffordable in less developed countries. In comparison, decentralized systems can offer low cost, easy operation and maintenance, and flexibility for wastewater treatment and reuse. An investigating • study was conducted to evaluate the performance of various decentralized wastewater treatment systems being used at selective wastewater treatment plants in the North India in terms, of their economics and treatment potential. Five full-scale decentralized wastewater treatment systems using Aeration cum Constructed Wetlands, Anaerobic filter cum Floating Plants, Fluidized Aerobic Bioreactor (FAB) and Submerged Activated Fixed Film (SAFF) Bioreactor with different process technologies were evaluated. Grab samples for six months from December to May 2008 were collected and analyzed in Environmental Engineering Lab, Department of Civil Engineering, Indian Institute of Technology Roorkee, Roorkee. for physico-chemical and microbiological examination. Additional information was gathered about facility operations,- the types of chemicals used and 0 & M related problems through review of files and interviews with plant personnel. Time series plots showing effluent parameter concentrations versus sampling frequency were prepared for analyzing the data. Further attempts have been made to establish the relationship between key wastewater constituents & operational parameters such as BOD, TSS and Turbidity with respect to TC & FC. The 0 & M related problems, observed during visits to STPs, were taken into account and attempts have been made for identification of the cause and rectification. Based on available records, the 0 & M cost (per year per MLD basis) was calculated for all STPs. From these studies, it was revealed that SAFF based plant is better than others in removing organic matter and comparable with Constructed Wetlands in removing coliforms. Floating Plants and Constructed Wetlands based plants are having lower 0 & M cost but land requirement is more. Overall performance of SAFF plant was found to be good.