Studies On The Extraction And Separation Technology Of Heavy Metals In Sewage Sludge

Taopu sewage sludge from Shanghai Taopu Municipal Sewage Plant was applied in this study. As an environmental benign chelating agent, poly-aspartic acid (PASP) was used to separate and remove the heavy metals from the sewage sludge based on chemical extraction technology.In the first part, the extraction process of heavy metals from sewage sludge with PASP has been studied. According to the analysis results of the characteristics of Taopu sewage sludge, a series of experiments were designed for the separation of heavy metals from the sewage sludge. Under different condiditions, the extraction processes were carried out. The effect of pH, the concentration of PASP, dip time, shake time and the addition of hydrogen peroxide were discussed. The results showed that PASP can efficiently extract Zn, Ni, Cu, Cd and Cr under the optimal experiment condition. The possible extraction mechanism of PASP was also discussed in this paper. It is indicated that PASP, as one kind of environmental benign compound, may play an important role in the green separation process of heavy metals from sewage sludge.With commercial cation exchange resin D113, the separation of heavy metals from the leaching solution of the sewage sludge was studied in the next part. Different condiditions, such as contacting time, the amount of resin and pH, were desigened for the investigation of the separation of heavy metals. The optimal experiment condition was obtained. The results indicated that resin D113 can efficiently separate heavy metals of the leaching solution.