Research On Near-zero Emission Of High-salt Wastewater In Coal-fired Power Plants

With the constant improvement of the environmental requirements,discharged wastewater in coal-fired power plant face the stress of substandard,therefore,a new way should be found to solve the practical problem.After a lot of research and communication,technologies be applicable to treatment of high-salt wastewater in coal-fired power plant are the conventional sanlian box process,two levels to clarify softening processes,membrane treatment technology and method of heat treatment technology,etc.Base on water quality characteristics of high-salt wastewater in coal-fired power plants,this article mainly aims at introduce high-salt wastewater near-zero emission technology from pretreatment,concentration,evaporation crystallization three aspects.On the basis of the pilot test,the feasibility of high pressure reverse osmosis technology and penetrating technology to treat desulfurization wastewater are examined.In order to reduce cost,the domestic part of the power plant using wet slag machine to consume desulfurization wastewater,the feasibility of this plan is demonstrated by this paper,and the vapor composition of introducing desulfurization wastewater into slag system are investigated in a simulation platform.The results show that power plant can use wet slag machine to consume desulfurization wastewater on the premise of strictly control the amount of water,which can alleviate the pressure of the subsequent processing.Forward Osmosis technology in the treatment of waste leachate already have very good applications,however,in the aspect of high-salt wastewater treatment in coal-fired power plants have less actual applications.At present,forward osmosis technology has been used in domestic project for desulfurization wastewater treatment,but because the short running time,the engineering application of this technology is not known clearly.In the case of feed water salinity is around 41000 mg/L,enrichment ratio is about 4-4.5 by applying one stage of two-section MBC system,the total dissolved solids is about 180000-200000 mg/L after concentrate water stripping,and there is no fouling and scaling signs of permeable membrane components during the test runingReverse osmosis technology has been used in the field of water-treatment for many years,and treat high-salt wastewater in coal-fired power plants with high pressure reverse osmosis technology has a unique advantage,due to its structure of wide flow channel,which can effectively avoid physical blocking phenomenon.The operating pressure of high pressure reverse osmosis components has 75 bar,150 bar and 200 bar three levels optional,which is the highest pressure rating membrane module for industrial application,in some of the applications of high concentration ratio,the solid content can reach more than 30%.Both of forward and reverse osmosis technology have merits and demerits in treating wastewater from coal-fired power plant.In order to reduce system energy consumption,a kind of new technology combined forward osmosis with reverse osmosis that aim at high salt waste water treatment has been proposed.