Application of membrane filter in wastewater treatment

The operation of coal washing wastewater collection system in power plant is discontinuous, and the instantaneous water quantity of Haining belt filter varies widely
   (1) high efficiency and low consumption, effluent can be discharged or recycled;
   (2) recovery of fine coal cuttings to reduce the loss of primary energy;
   (3) good cleaning effect, no secondary pollution.
   for the treatment of coal slime wastewater with suspended solids content up to 30000 mg / L, the general conventional method is denied because of its large area, secondary pollution and inability to recover fine coal chips. On the basis of technical comparison, membrane filter is selected as the main filtration equipment.
   the working principle of membrane filter is the application of micro filtration technology. It is mainly composed of cylindrical cone bottom shell, internal filter element, related valves and control equipment. The key component is the filter element which is composed of the framework and the filter bag on the framework. The filter element is fixed on the porous plate on the upper part of the filter, and the porous plate divides the filter barrel into two parts: the lower chamber and the upper chamber. The filter bag is made of polytetrafluoroethylene microporous filter membrane and related substrate, and made of hydrophilic composite filter material after hydrophilic treatment. The filtration principle of microporous membrane is to use the relatively uniform micropores on the membrane to intercept the particles in the filtered liquid whose particle size is larger than the pore size of the membrane, such as suspended solids, bacteria, colloids, etc.
   microfiltration, ultrafiltration and reverse osmosis are driven by pressure difference to achieve the purpose of separation and concentration, without phase change and interfacial mass transfer. Microfiltration membrane is one of the effective methods for solid-liquid separation, which can collect all the suspended solids in the liquid on the surface of microfiltration membrane. Microfiltration is a kind of precision filtration technology. The pore size ranges from 0.1 μ m to 10 μ m, which is between conventional filtration and ultrafiltration. According to the characteristics of very fine suspended particles in coal containing wastewater and considering that the effluent from the filter will be recycled, the microfiltration membrane pore size of the membrane filter for wastewater treatment in coal slime pond of Yangshupu power plant was determined after water sample filtration test. PTFE microfiltration membrane has the following characteristics
(1) Membrane surface filtration, no initial filtration period, high filtration precision, one-time purification;
(2) Low filtration resistance, low working pressure and low energy consumption;
(3) No medium falling off, good cleaning performance and low recoil pressure;
(4) It has a wide range of filtration and operating temperature and excellent chemical stability.