Development Of In-situ Chemical Stabilization Reagents For High-level Heavy Metals Contamination

In recent years, with the rapid development of China’s industry and economy, soil pollution frequently occurs, such as explosion, leakage, waste-water untreated discharge and other emergency environmental events (including high-level heavy metals contamination), directly threaten people’s health, environmental and social security. At present, mending methods for heavy metals contaminated sites, have been involved in engineering technology, physical chemistry, biotechnology and many other aspects. As one method of these, in situ solidification / stabilization technology which is low cost, easy to operate, able to handle a variety of pollutants, is efficient and effective. The method is adding reagents to react with heavy metals pollutants, in order to reduce the migration of contaminants, biological validity etc, to achieve repairing. In order to improve the ability of response to sudden high-level heavy metals pollution, carry out in situ solidification / stabilization technology research for high-level heavy metals contaminated sites is necessary.After collecting different regions and different pH values soils as tested soils, the experiment select the alkaline materials, phosphorus-containing substances, sulfur substances, ferrous substances, clay minerals, separately to treat different heavy metals(Cu、Pb、Zn、Cd、Ni、Hg、Cr、Ag、Mn) and metalloid (As) contamination, use TCLP method to evaluate the results. According to the results, confirm the stability and efficiency of the solidification / stabilization reagents.Based on the results of solidification / stabilization reagents test, while Cd for the main pollution element, Cu、Pb、Zn、Ni or As、Cr for the secondary pollution elements in soils, or As for the main pollution element, Cu、Cr for the secondary pollution elements in soils, or Cu、Pb、Zn、Cd、Ni、As for the main pollution elements in soils, select the appropriate reagents to treat the contaminated soils, using sulfuric acid & nitric acid method to evaluate the results. According to the results, confirm the efficiency of the reagents mixture.The results of the reagents selected experiment and the reagents mixture experiment show that: Phosphorus materials are mainly used to treat Pb contaminated soils, for contaminated soils with other metal elements except“As”element also have good stabilizing capacity; Sulfur materials mainly used to treat Hg, As contaminated soils, for contaminated soils with other elements might also be useful; Ferreous materials are mainly used to treat As, Cd, Cr, Hg contaminated soils, for other metal pollution might be negative impact; Alkaline materials and clay minerals are useful for cationic form of heavy metals contamination, they could change the physical and chemical properties of the soils, enhance the buffering capacity of the soils. In the reagents mixture experiment, there are three compoundings successful, provide protection for the future while treating heavy metals contaminated soils in situ.