Experimental Study On The Treatment Of Typical Heavy Metal Wastewater In Xiangjiang River Basin By HDS Method

Currently, the pollution problems of Xiangjiang river basin, especially theheavy metal pollution, can not be ignored any more. The discharge of heavy metalwastewater not only causes damage to the ecology, but also seriously affects thehealth of residents. The treatment of heavy metal pollution in Xiangjiang basinshould be started from the sources, and inhibit the phenomenon of “polluting whilecontrolling”, therefore, the heavy metal pollution will be relieved fundamentally.Heavy metal wastewater has been an important issue in the field of water treatment.New and effective treatment technologies should be developed vigorously so as toreduce the emissions of it from the sources.Based on traditional chemical precipitation method and combined withpractical production process, this paper suggests using the High Density Sludge (HDS)method to control heavy metal wastewater. The experiment compared and analyzedthe different effects to the Zn2+, Cd2+, Pb2+contained wastewater respectively and tothe mixture wastewater by using both traditional chemical precipitation method andHDS method, discussed the effect of precipitant, high density sludge and dosage offlocculant and coagulant to the concentration and turbidity of the residual ion.Besides, the experiment investigated how the dosing method of the sludge affectedthe final effects. The orthogonal test was designed respectively based on theinfluence of hydraulic conditions and the dosing order of reagents on the effluentquality. This paper delves into the dynamic theory of HDS method and explains themechanism of high density sludge systematically.The results showed that, for single heavy metal wastewater which respectivelycontained Zn2+, Cd2+, Pb2+, the removal rates were99.64%,99.93%and99.69%under the best condition of the traditional method, however, the removal rates couldachieve99.86%,99.96%and99.84%under the best condition of the HDS method. Asto the mixture wastewater, the removal rates of the three heavy metal above were99.82%,98.39%and99.96%for conventional method, and99.91%,99.82%and99.90%for HDS method.Compared to the traditional method, HDS method shows a better treatmenteffect on the typical heavy metal contained wastewater with less dosage of reagents.In addition, seldom effluent quality changes are found when chemical dosagefluctuates in a certain range. It means that HDS method has a stronger capability to impact load. Furthermore, the precipitation time of the HDS method is shorter thanthat of traditional methods, while the stirring intensity is slightly higher. To sum up,the HDS method has wide application prospect and development space because of itsadvantages of low-cost, simple operation and high efficiency.