Application Of Thermal Desorption Technology In Remediation Of Organophosphorus-Pesticides(OPPs)Contaminated Soils

According to the condition of serious OPPs pollutionin a Tianjin pesticide factory, we chose the thermal desorption technology to researchremoval characteristics of OPPs,andestablishing thedominant factors and ranges which influence onthe OPPsremoval ratein lab.Then the laboratory experimentwas verifiedin theremediationofOPPs soils. At the same time, the potential and ecological value of the remedied soil was also studied. The results were showed as follow.(1)The laboratory test results showed that the changes of the thermal desorption temperature and thermal desorption time would influence the results of thermal desorption of soil organic phosphorus pollution. Within 20-30 mins, the removal of organic contaminants in soil phosphorus was the fastest. The removal rate could be above 90%. In the low temperature operation stage, the sequence of pollutant removal efficiency by thermal desorption form high to low was dichlorvos, omethoateand parathion. At the same time, the soil particle size would affect the removal efficiency of the organophosphorus pesticides. The larger the soil particle size, the higher the soil organic phosphorus removal efficiency.(2)The pollutants were mainly as dichlorvos, omethoate and parathion in the Tianjin pesticide factory. At desorption temperature of 400 ?, desorption time of 30 min, the removal of soil contaminants was basically stable and the removal efficiency could maintained at more than 90%; When the removal efficiency values of dichlorvos, parathion and omethoate in the contaminated soil reached their maximum values, the residues of three pollutants in soil were only 0.34 ppm, 0.12 ppm and 0.65 ppm, respectively.(3)Compared with the growth of Amorpha in the normal soil, no significant difference was found in the plant growth and root development of Amorpha in the thermal desorption soil after the phytoremediation of one growing season. The rhizosphere soil microenvironment had a great improvement, and the microbial biomass and enzyme activity in rhizosphere soil reached the normal soil level. Hence, the thermal desorption soil has a highly ecological value.