Comparative Analysis of Multiple Effect Evaporator and Membrane Distillation for Wastewater Reclamation

Pesticide industries produces high TDS streams during course of its manufacturing operations which cannot be treated by conventional treatment process. The industry has to treat high TDS waste water with dissolved solid in range of 10-13%. Treatment of high TDS streams is conventionally done through reverse osmosis or multiple effect evaporators. Reverse Osmosis is comparatively cheaper in treatment cost but it has limitation of inlet feed TDS concentration. Reverse Osmosis cannot treat TDS more than 3-4%, with recover of 50-60%. Multiple Effect evaporator is alternative technology which treat high TDS waste water, but it has very high capital and operation cost. The company has challenge to optimize the cost of waste water treatment, which finally contributes to cost price of product. Higher treatment cost increase cost price of product and reduce margin and profitability. Membrane distillation is an emerging technology for treatment of high TDS effluent streams and recovery of good quality water for reuse in manufacturing process [6]. MD is a non-isothermal membrane separation process, in which the water vapour molecules are transferred through a microporous hydrophobic membrane. MD is a environment friendly process [7]. Driving force is the partial pressure difference across the membrane that is created by the temperature difference between the two sides of the membrane. In MD we can get better result by using nanofiber membranes for distillation [10]. This is an attractive alternative solution for effluent treatment, giving high quality distillate and the possibility of operating at low temperatures [5]. Some multinational industries in India are using membrane distillation process for better result [4]. Compared to other membrane separation processes, MD operates at low pressures, lower than the pressures of the reverse osmosis (RO). Moreover, the capability of utilizing solar thermal energy or waste heat from other processes makes MD an energy and cost-efficient and environmental friendly process.