| According to the toxicity of nitrite and nireate, and the nitrogen contamination in surface and ground water, triple-nitrogen contamination became a problem of drinking water safety. Therefore, our country and many other countries of the world established strict limitation of triple-nitrogen in drinking water criterion. Our country's standards for drinking water were implemented on 1st July, 2007. The new criterion inhanced the water quality's demands of organic compounds, microorganism, and disinfection and so on. And it reached the standards for drinking water in developed countries in the world.The hydro-clarifier of micro-vortex was designed, which was based on the research hotspot of high density clarifying technology and in combine with vortex diffusion, sludge suspension layer, wing sheet type separator theory and material balance calculation equation. This clarifier's mechanism and effectiveness of water purification was identified by the raw water with the sediment of Chan River. And three common coagulants(PAC,PAFC and PAM)were also selected to finish the experiment. The conclusions were below:(1)This clarifier completely depended on the effect of water flow to ensure the flock's stabilization of suspension, turbulence and tendencies. Its character was similar to plug-flow-reactor. The backmixing phenomenon did not exist so the clarifier could be achieved to fix the agents intensively. Besides, the mature floccule and the tiny floccule keep in touch flocculating and form the high density reticular floccule after adding the coagulant aid. It can strengthen the adsorption among the mature floccule, enhance the speed of flocculating and make the original water get finer clarification.(2)This clarifier's high-efficient circulation was on the premise of adding the organic polymer coagulant aid. Furthermore, the experiment of motion water approved that the effect of adding PAFC and PAM was better than that of adding PAC and PAM in this equipment.(3)This clarifier was circulated in stability operation. Under the normal condition, the general turbidity of effluent water was between 0.8 and 1.8 NTU. And CODMn, UV254, ammonia nitrogen, NO2--N and NO3--N all reached the drinking water criteria without filtration. In addition, the removal rate of ammonia nitrogen could be stabilized with more than 60%, and it was up to 85.4%. The removal rate of NO2--N was between 63.3～92.3%. The removal rate of NO3--N was between 74.9～83.2%.(4)This clarifier has small floor area, its surface load is higher than the general clarifier.
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