沼渣与硫酸亚铁共处置含铬土壤的协同机制研究

Investigation on the oynergistic mechanism of co-disposal of chromium-containing soil by digestate and ferrous sulfate

利用沼渣和硫酸亚铁对含铬土壤进行共处置,在初步优化处置工艺参数后对共处置的协同效应进行验证,并通过XPS分析和微生物群落分析揭示了协同效用机理.结果表明,沼渣和硫酸亚铁共处置含铬土壤可实现土壤Cr(Ⅵ)含量低至未检出(检出限0.2mg/kg),优于硫酸亚铁处置法.共处置还原速率高于沼渣单独处置.微生物群落结构分析表明共处置组别细菌群落丰度与多样性高于沼渣单独处置,共处置土壤铬还原菌的相对丰度明显提高.此外,共处置组别内铁还原菌和硫酸盐还原菌的相对丰度也显著提升.通过XPS分析,共处置后的土壤中存在Fe(Ⅱ)、亚硫酸盐和硫化物,结合微生物群落分析结果,证实了铁和硫催化微生物还原六价铬过程.本研究为低碳型高浓度Cr(Ⅵ)污染土壤的治理提供新的思路.

Digestate and ferrous sulfate were combined to co dispose the chromium-containing soil,the synergistic effect of co-disposal was verified after the preliminarily optimizing of disposal parameters,and the synergistic mechanism was revealed by XPS analysis and microbial community analysis.Co-disposal of digestate and ferrous sulfate could reduce the content of Cr(Ⅵ)in soil to undetected(the detection limit was 0.2mg/kg),which was better than that with ferrous sulfate treatment,and the reduction rate of co-dispose was higher than that of digestate alone.The analysis of microbial community structure showed that the abundance and diversity of bacterial community in co-dispose group was higher than that in digestate alone,and the relative abundance of chromium reducing bacteria,iron reducing bacteria and sulfate reducing bacteria was significantly increased in the co-dispose soil.XPS analysis showed that Fe(Ⅱ),sulfites and sulfides were present in the soil after co-dispose.Combined with the results of microbial community analysis,the process of microbial catalytic reduction of Cr(Ⅵ)in digestate by iron and sulfur was confirmed.This study provides a new idea for the treatment of low carbon high concentration Cr(Ⅵ)contaminated soil.