Study On Reusing Of Municipal Wastewater For Production Water Of Thermal Power Plant

In this paper, according to the characteristic of recycled water from municipal sewage in high salt, high organic matter content, high content of bacteria, complexty of bacterial species, high ammonia nitrogen content, and corrosion resistance, etc., the systematically research was carried on for these problems, such as using lime coagulation, scale inhibitor, corrosion protection, sterilization and other issues. The study results were as follows:Water used in circulating water filling water system back in the city, to reduce the lime content water pH 9.5 to 10.0, control of poly iron in 10-50 mg/L, control the content of PAM in 1.0 2.0 mg/L, is advantageous to the lime coagulation treatment; Control of lime water hardness under 5 mmol/L, control water alkalinity tendency in 1.2-2.0 mmol/L, control turbidity under 5 NTU, guaranteeing the safe operation of the circulating water system. Adding a certain amount of sodium carbonate to the lime adding system can decrease water hardness. And the TP317 L material circulating water pipe is conform to the specifications for design of industrial circulating cooling water treatment(GB 50050-2007) of copper and stainless steel equipment which should be less than 0.005 mm/a request. Because of nitrosation reaction and nitration, its scale tend to be smaller, with impact on the corrosion of circulating water system material is given priority to, the more serious nitration, causing circulating water pH lower system which of alkaline treatment should be considered. The ammonia nitrogen in water can react with oxidized disinfectant sodium hypochlorite and so on, and do not react with chlorine dioxide, when high ammonia nitrogen in water reuse using chlorine dioxide as oxidizing bactericide circulating water system, and alternating with non oxidizing bactericide dosing, will get better results.For reusing of municipal wastewater as make-up water of boiler, inlet water hardness, regenerated liquid concentration, and the displacement drainage hardness should be controlled to lower than 5mmol/L in sodium exchaged bed, above 5%, and under 3mmol/L, respectively. And the weak acid bed inlet water hardness and basicity should be strictly controlled to below 1mmol/L and 1.2-1.2mmol/L, respectively. The inlet water hardness of reverse osmosis system must be approach 0, SS and iron ions of the water intake must be low, and the water SDI should be less than 5. More water flow can reduce deposition rate of harmful substances in the reverse osmosis membrane surface, which can improve the stability of the operation, and reduce the frequency of chemical cleaning.