优化热脱附技术对十溴联苯醚污染土壤的适用性及修复效果

Adaptability and Remediation Effect of Decabromodiphenyl Ether-Contaminated Soil Using Optimized Thermal Desorption

为了探索绿色、高效、环保的修复PBDEs污染土壤的技术,在热脱附技术基础上将木炭同时作为尾气吸附剂和燃烧热源,处理不同十溴联苯醚污染水平的PBDEs(多溴联苯醚)污染土壤,通过14种不同溴代PBDEs同系物分析十溴联苯醚的降解产物组分并计算其去除率.结果表明:在热脱附技术处理后,十溴联苯醚初始污染水平分别为500、800和1 000μg/kg,污染土壤中PBDEs的去除率分别为63%、81%、94%.14种不同溴代PBDEs同系物在热脱附反应后的残留产物中均有检出,其中热脱附处理后的土壤中以三溴和四溴PBDEs产物占优势,而尾气中则以四溴和五溴PBDEs产物为主.根据热脱附试验前后土壤中PBDEs的结构组成对比及分析可知,降解和脱溴反应在整个热脱附反应过程中发挥了重要作用.另外,XAD树脂吸附柱中虽有少量的氯代和溴代二英类物质(PCDD/Fs和PBDD/Fs)被检出,但其毒性当量浓度均小于0.1 ng/m^3,符合欧盟、日本及我国所规定的二英物质排放标准.研究显示,在利用优化的热脱附技术修复十溴联苯醚污染土壤过程中,PBDEs的去除率与污染土壤中其污染水平相关,并且热脱附过程以降解及逐级脱溴反应为主.

In order to investigate a green,highly efficient and environmentally-friendly technology for remediation of decabromodiphenyl ether-contaminated soils, charcoal was used as both the effluent adsorption and thermal source in the treatment process of decabromodiphenyl ether-contaminated soils on the basis of conventional thermal desorption technology, in order to analyze the decomposition products and removal rate of decabromodiphenyl ether through identifying the 14 kinds of PBDEs isomers. The results showed that the removal rates for three different initial concentrations of 500,800 and 1000 μg/kg of contaminated soils were 63%,81%and 94%,respectively,after the thermal desorption technology was applied. Fourteen kinds of PBDEs components were detected in the residue products after the thermal desorption process. Among the PBDEs isomers,the concentrations of Tri-BDE and Tetra-BDE were much higher than those in the treated soils,whereas the concentrations of Tetra-BDE and Penta-BDE were predominant in the effluent gas.In terms of the components＇ comparison and analysis of PBDEs in soils before and after the thermal treatments,degradation and debromination reactions played an important role in the whole process of thermal desorption. Furthermore, although a small number of dioxins, including PCDD/Fs and PBDD/Fs, were detected in the XAD adsorption resin from effluent gas,TEQ values were uniformly less than 0. 1 ng/m^3,which complied with the emission limit standard values of EC,Japan and China. Theresults showed that the removal rate of PBDEs was related to the initial concentrations of contaminated soils,and the degradation reactions and stepwise debromination predominated in the treatment process using the thermal desorption.