DEVELOPMENT OF OPTIMUM WASTE WATER USING NETWORK

Abstract

Water is a most important utility for many industrial operations, and is utilized for many purposes in industrial processes. The high growth in population, with industrialization and urbanization, resulted increase demand for water, coupled with generation of waste water leading to serious danger on the environment. Therefore, there is increasing pressure in the process industries to reduce fresh water consumption and waste water generation. Water optimization techniques can perfectly reduce overall fresh water consumption and waste water generation as well as lower cost of fresh water and effluent treatment costs. There are many approaches/methodologies are available to save water and reduction of waste water generation. Mathematical optimization is one of the most important methodologies for waste water minimization, optimized the water utilization processes of an industry, and considers the how to reduce the water quantity and quality to each water using processes, so that water reuse and recycle approaches is maximized to design the optimum water using network simultaneously reduce the waste water generation. Flie present study deals with three case studies are discussed in detail. All cases had been considered as retrofitting problems and solved very precisely considering existing fixed network costs, present cost of power consumption and recent market price of different sizes of pipes. The first case study involves four processes and single contaminant problem and three approaches of water minimization i.e. reuse, recycle reuse, regeneration reuse are applied. The GAMS (Version 4.2.03 and solver was CONOPT) software was used to mathematical programming, The initial fresh water consumption is 185 tph and after modification using mathematical programming it reduces to 90 tph (reuse), 90 tph (recycle reuse) and 46 tph (regeneration reuse). The cost benefit analysis is obtained in the case of reuse is 115 1265481NR per year and payback period is 8.11 days, recycle reuse is 115 126548lNR per year and payback period is 8.68 days, and regeneration reuse is 1 684483 I7INR per year and payback period is 7.8 days. The second case study is identified as a multi contaminant, reuse problem. The initial - fresh water consumption using mathematical programming is 258 tph and after optimization of network is 139.7 tph. the cost benefit analysis is obtained is 69296618lNR per year and payback period is 12 days. The results obtained from the present analysis is compared with the ASPEN WATER and WATER PINCH software's which uses mathematical programming and pinch technology. The third case study is also multiple contaminant problem which involves eight operations and only water reuse approach is applied. The initial fresh water consumption is 329 tph and after optimization is 189 tph. The cost benefit analysis is obtained is 169632303lNR per year and payback period is 8 days. The results of this problem are also verified with both software's solutions.