The Research On Optimization Process Of Brackish Water Desalination Based On Agricultural Irrigation

Our country is a powerful area of agricultural. Cultivated land around the country has a large proportion. But China also a country who is very lack of water, and the water resource of per person only the quarter level of the which in the world. Instead, our country have access to reliable brackish water, so brackish water desalination technology is considered to be the important measures to improve the shortage of water resources. It is the great significance to the development of national economy to researching the application of brackish water desalination in agricultural production. In recent years, membrane separation technology has been great valued. In this thesis, brackish water desalination processes which using electrodialysis, reverse osmosis membrane and forward osmosis membrane technology has been studied and optimized.This thesis discussed the use of homemade electrodialysis reactor in brackish water desalination process. The optimal experimental parameters was determined during the process of desalination simulation brackish water. The initial concentration of the brackish water was 5000 mg/L. Experimental results show that when the concentration of brackish water fell to 500 mg/L, the best working voltage was 15 V, the energy consumption cost was 2.13 yuan/m3, salt rejection rate as high as 90%. On the basis of brackish water desalination, we studied the use of electrodialysis technology in micro-brackish water desalination. The result show that when the concentration of brackish water fell to 500 mg/L from 3000 mg/L, the best working voltage was 15 V, the energy consumption cost was 1.43 yuan/m3, salt rejection rate as high as 90%. Considering various aspects, electrodialysis technology can be used as a economic and efficient operation for brackish water desalination.This thesis also studied the brackish water desalination using forward osmosis technology. This experiment selects three different solution as draw solution. We have studied the permeability of self-made cellulose acetate membrane and commercial membrane by studying the change of water flux and salt rejection, and chosen the most suitable draw solution. Results show that when choose potassium chloride as draw solution, the value of water flux was greatest compared with other kinds of draw solution for both self-made cellulose acetate membrane and commercial membrane. And as can be seen by comparing, commercial cellulose acetate membrane performance was better than self-made cellulose acetate membrane. After a series of research and the test, the energy consumption cost was 1.16 yuan/m3At the same time, this paper optimized the brackish water desalination system with reverse osmosis membrane. On the basis of effective utilization of water, this thesis analysed several aspects of the system. For example: design principles, comprehensive analysis of the water resource, design of pretreatment system and reverse osmosis desalination system, design the pool, calculation of the energy consumption and analysis of the problem. Finally it was concluded that energy consumption cost of brackish water treatment about 1.32 yuan/m3.Finally, in this paper, through comparison and analysis from the aspects of technology and the amount of energy consumption of electrodialysis, forward osmosis, reverse osmosis. Integrated all factors, it was concluded that the most optimal scheme of brackish water desalination was reverse osmosis technology.