Study On Washing Remediation Of The Heavy Metal Contaminated Soil

Soil is the material basis of mankind live with and the last defensive line to against pollutions of nature. With the fast developing of industry and agriculture, the waste water and residue were discharged recklessly and thus resulted in serious soil polluting in China. Soil washing remediation has incomparable advantage towards to other remediation owing to its minor-cycle, efficiency and few restrictions on polluting level, however has its own environmental pollutions. According to the existing studies, the property of washing agent is the most important and thus need to be hypotoxicity. Therefore, to develop an efficient and eco-friendly washing agent is the main factor for further improvement of soil washing technology, and which is a significant scientific issues on soil remediation.In this work, we aimed at the washing performance towards soil and tailings polluted by heavy metal using a series of washing agents and washing methods, and we studied the priority and potential of the biodegradable PASP using as the washing agent and draw a conclusion as blow:1. The heavy metal obliterating effects of different washing agent using shake-washing methods were studied and investigated the influence of environment factors. The removal proportion tended to constant value when the water/soil mass ratio was20to1and the washing time was6h according to the experiment results. EDTA, oxalic acid, citric acid and tartaric acid showed the preferable heavy metal removal effect among all used washing agent. The Cu, Pb, Zn and Cd removal proportion was77.36%,92.06%,85.00%,95.24%using0.3M oxalic acid, respectively. The Cu, Pb, Zn and Cd removal proportion was62.36%,38.74%, and68.64%using0.2M citric acid, respectively. The Cu, Pb, Zn and Cd removal proportion was68.26%,18.08%,70.40%, and55.79%using0.2M tartaric acid, respectively.2. The heavy metal obliterating effects of different washing agent using earth-pillar washing methods were studied on tailings. The optimal washing rate is1.5mL/min and the optimal water/soil mass ratio is2to1in the earth-pillar washing method according to the experimental results. Tartaric acid showed obvious washing effect to Cu and Zn in the tailing samples, the removal proportion can reach as high as30.32%and47.74%, while EDTA showed a removal proportion of53.97%to Pb according to the experimental results. The removal proportion of Cu, Pb and Zn can reach46.59%,51.27%and48.10%through the classification washing method using tartaric and EDTA in sequence.3. The heavy metal obliterating effect on soil of PASP through shake-washing method and environmental security was also investigated. The Cu, Pb, Zn and Cd removal proportion can reach70.00%,32.39%,72.60% and88.75%using the mixing solution of0.2M citric acid and PASP. According to the environmental security test, the CAT activity of zebra-fish can be proved and thus improved the anti-toxic after adding PASP.