微生物与生物炭复合修复铬污染土壤的室内试验研究

Experimental Study on the Remediation of Chromium Contaminated Soil by Microorganism and Biochar

以铬污染土为研究对象,通过浸出试验、Cr(Ⅵ)残留值试验、BCR连续提取试验研究了巴氏芽孢杆菌(Bacillus pasteurii)、生物炭及巴氏芽孢杆菌与生物炭复合对铬污染土壤的修复效果。结果表明:经过20 d修复后,所用添加剂均能够修复铬污染土壤,但菌液与生物炭复合的修复效果优于菌液和生物炭,且菌液的修复效果要优于生物炭;其中,当菌液浓度OD600为1.0与生物炭浓度40 g/kg复合时,土壤浸出浓度和土壤中Cr(Ⅵ)含量分别从90 mg/L、270 mg/kg降低至1.08 mg/L、5.14 mg/kg,修复效果最好;同时,3种添加剂均提高了土壤的pH,均促使铬从弱酸态向可还原态和残渣态转化,而对可氧化态铬影响不大;由X射线光电子能谱分析(XPS)分析可知巴氏芽孢杆菌与生物炭复合修复铬污染土壤为混合吸附和还原的过程。

To study the remediation effects of Bacillus pasteurella, biochar and combination of B.pasteurlla and biochar on chromium contaminated soil, by leaching test, Cr(Ⅵ) residual value test, and BCR(B-cell receptor) continuous extraction test. The results show that the above additives can repair chromium-contaminated soil after 20 d restoration, the remediation effect of the combination of bacterial solution and biochar is better than that of bacterial solution and biochar, and the remediation effect of bacterial solution is better than that of biochar. Among them, the treatment effect is the best at the bacteria concentration of 1.0 and biochar of 40 g/kg, at which the leach concentration and Cr(Ⅵ) content in soil is reduced from 90 mg/L and 270 mg/kg to 1.08 mg/L and 5.14 mg/kg, respectively. At the same time, the three additives increase the pH of soil, promote the transformation of chromium from weak acid state to reducible state and residual state, and has a little effect on the oxidizable state of chromium. As revealed in the analysis of XPS(X-ray photoelectron spectroscopy), the mechanism of the remediation of Cr-contaminated soil combining B. pasteurlla and biochar is a process of mixed adsorption and reduction.