发酵松树皮和花生壳对地下水中砷的减毒效应

Detoxification effect of fermented pine bark and peanut shell against groundwater arsenic

本研究探索了通过发酵的松树皮和花生壳强化地下水中土著微生物活性来降低砷毒性的方法.静态批实验结果表明地下水中化学氧化和生物氧化过程的耦合,会促使As(Ⅲ)转化为As(Ⅴ),从而降低砷的毒性.加入有机基质可提升As(Ⅲ)的去除效率,花生壳的效果强于松树皮.通过对实验体系的化学及微生物表征,发现有机基质促进As(Ⅲ)减毒的主要机理如下:a)释放有机物,造成体系Eh值升高(即氧化性增强),从而促进As(Ⅲ)的化学氧化反应;b)为微生物生长提供有机碳源,促进砷代谢细菌、砷氧化细菌及反硝化细菌增长,从而强化As(Ⅲ)的微生物氧化反应.此外,有机基质对砷的吸附也在一定程度上降低了砷的浓度.研究结果揭示了应用农业废弃物治理地下水中砷污染的新思路,对于原位绿色修复砷污染地下水具有一定科学价值.

This study explored a new approach for groundwater arsenic detoxification by bio-stimulation using fermented pine bark and peanut shell.Batch experiment results suggested that the coupled processes of chemical and microbiological oxidation in the groundwater led to the transformation of As(Ⅲ)to As(Ⅴ),resulting in arsenic detoxification.Organic substrate enhanced the removal efficiency of As(Ⅲ),the effect being stronger for the peanut shell than the pine bark.By monitoring the chemical and microbiological conditions of the experimental system,we found that organic substrate enhanced the arsenic detoxication by the following mechanisms:a)organic carbon released by the substrate increased the system Eh,making the system more oxidative,and thusly the chemical oxidation of As(Ⅲ);b)the organic carbon,as nutrient for bacteria,promoted the activity and growth of the bacteria capable of arsenic metabolism,oxidation and denitrification,and consequently reinforced the microbiological oxidation of As(Ⅲ).Furthermore,the organic substrate may adsorb arsenic and reduce its concentration to certain degree.The new strategy of using agricultural waste for treating arsenic contaminated groundwater was scientifically valuable for development in green in-situ remediation technology.