Application Of RO Technology To Mid-water Reused In Power Plant

Supply of fresh water in the world is finite and threatened by pollution. Increasing water demands for agriculture, industry and urban water supply leaded to competition for the allocation of limited fresh water resources. In order to avoid water crisis, every country aims to protect water resource, manage water supply and demand, reduce pollution, and lessen the impact of increasing population on the water environment. Municipal sewage reuse is a way to save clean and top - quality water by recycling treated sewage to places where it can be used. It is one of the effective measures to ease the problem of freshwater shortage in China. Agricultural irrigation, industry, scenic water and groundwater recharge are the main approaches of wastewater reuse. The treatment and reuse of sewage establish the second water source and reduce the fresh water needed by the city and increases the reliability of water supply, and then greater demand of human can be fulfilled with less fresh water. So the impact of human life on the water environment was lessened. According to the local actual situation, different wastewater reuse approaches be selected in different regions of china to reuse the municipal wastewater is the important method to alleviate the shortage of water resources and realize the goal of sustainable water resources utilization, and has the visible economic benefit, social benefit and environmental protection benefit.Sewage treatment and reuse as cooling-water can not only enlarge the scale of wastewater reused, but also supply a sufficient headwater. Dalian Beihai Thermoelectricity Generation Company used effective moving-bed bioreactor + coagulation, precipitation + two-stage filtration + Reverse Osmosis system to treat secondary effluent from Chunliu wastewater treatment plant, the produced water reused as cooling-water and boiler make-up.The whole system operated stable during 240 days, the turbid of pre-treatment water is less than 0.1NTU, the SDI of pre-treatment is stable between 3.5 and 4.5, and pre-treatment has no surviving C1, which are in line with the requirements of RO system. Conductivity of water from RO system was controlled below 20μs/cm while desalination ratio is more than 98%. Through the observation on the variation of electric conductivity, water yield, operational pressure, pressure difference, the reason on their variation and the relation between them were discussed. RO system was evaluated impersonally by standardization of desaltification ratio, water production and pressure difference.