TECHNO ECONOMIC EVALUATION OF VARIOUS WASTEWATER TREATMENT PLANTS

Abstract

One of the greatest challenge that India is facing today is the gradual depletion of natural reserve of water and land against the growing demand of water, food and shelter by an ever increasing population, which has crossed the one billion mark. As per the census 2001, the total land area of India is 9600000 sq km and its population 1.027 billion. To feed and supply water to such a gigantic population is a huge task and it surely calls for recycling of water and judicious use of land. The study highlights the application of the Techno Economic Analysis tools for the selection of appropriate technology of sewage treatment and aims to provide guidance/methodology in incorporating state-of-the-art STP technology selection suitable for urban, semi-urban, mega and metro town, which can significantly cut treatment and disposal costs. As there are many Sewage Treatment technologies available for the treatment and reuse of sewage in India, and in this study five existing sewage treatment technologies that are mostly used are selected for techno evaluation analysis in terms of three basic parameters: BOD, TSS and Fecal Coliform, as per NRCD direction. The economic evaluation of technology is made by calculating the Life cycle cost analysis considering three major variables/parameters that affect the selection, are taken into account for analysis: capital cost, annual maintenance cost, and land cost. Detailed design of various STPs is prepared to arrive the capital cost and land area required per MLD, for life cycle cost analysis. It is observed that the Waste Stabilization Pond is the most economical and cost effective technology to treat municipal sewage where the cost of land is low i.e. approx. in the range upto Rs. 50 Lacs per ha. Where the cost of land is medium, i.e. beyond Rs. 50 Lacs per ha, the Upflow Anaerobic Sludge Blanket (UASB) with final polishing pond is economical, upto Rs. 1 OOLacs per ha. For high land cost or scarcity of land Fluidized Aerobic Bed (FAB) Reactor, Sequencing Batch Reactor (SBR) & Activated Sludge Process (ASP) are found to be economical. The treated effluent from Sequencing Batch Reactor (SBR) as can be reused for non-potable purpose like, gardening, car washing, toilet flushing, as effective option to conserve the potable water. The revenue generation potential from UASB with FPU is the highest, as the treated effluent preserving N, K, & P, is suitable for irrigation, use of dry sludge as manure, utilization of bio-gas generated for power saving and encouraging aquaculture in FPU.