SRB对AMD湿地处理系统沉积物中重金属的钝化作用研究

Study of SRB on the Passivation Effect of Heavy Metals in AMD Wetland Treatment System Sediments

湿地沉积物既是重金属污染的汇,也是重金属污染的源,沉积物修复技术中的微生物钝化技术是实现重金属原位修复的一种重要手段。以酸性矿山废水(Acid Mine Drainage,AMD)湿地沉积物为对象,研究了硫酸盐还原菌(Sulphate Reducing Bacteria,SRB)对湿地沉积物中铁(Fe)、锰(Mn)、铜(Cu)和锌(Zn)释放及形态的影响,探究了SRB对沉积物中重金属的钝化效果。结果表明:在沉积物中接种SRB可不同程度地提高浸出液p H、电导率(EC)值,降低氧化还原电位(Eh)和硫酸盐(SO_(4)^(2-))浓度,当SRB的接种体积大于100 mL时,浸出液中Fe、Mn、Cu的浓度显著降低,当接种体积为200 mL时,浸出液Zn的浓度显著降低;接种SRB可使沉积物中Fe由弱酸提取态和可还原态转为可氧化态,使可还原态Mn向弱酸提取态及可氧化态转化,而沉积物中Cu、Zn则由弱酸提取态向可氧化态转化;接种14 d后,SRB接种体积为200 mL的处理组中沉积物中Fe、Mn的钝化效率最高,接种体积为100 mL的处理组中SRB对Cu和Zn的钝化效果最为明显。

Wetland sediments are not only the sink of heavy metal pollution,but also the source of heavy metal pollution.Microbial passivation technology in sediment remediation technology is an important means to achieve in-situ remediation of heavy metals.The wetland sediments of acid mine wastewater(AMD)are taken as the object,the effects of sulfate reducing bacteria(SRB)on the release and speciation of iron(Fe),manganese(Mn),copper(Cu)and zinc(Zn)in wetland sediments are studied,and the passivation effect of SRB on heavy metals in sediments is explored.The results show that the inoculation of SRB in the sediments can increase the pH and conductivity(EC)value of the leaching solution to varying degrees,and reduce the redox potential(Eh)and sulfate(SO_(4)^(2-))concentration.When the inoculation volume of SRB is greater than 100 mL,the concentrations of Fe,Mn and Cu in the leaching solution are significantly reduced.When the inoculation volume is 200 mL,the concentration of Zn in the leaching solution is significantly reduced.Inoculation of SRB can change Fe from weak acid extractable and reducible to oxidizable,Mn from reducible to weak acid extractable and oxidizable,and Cu and Zn in sediment from weak acid extractable to oxidizable.After 14 days of inoculation,the passivation efficiency of Fe and Mn in the sediments of the treatment group with SRB inoculation volume of 200 mL is the highest,and the passivation effect of SRB on Cu and Zn in the treatment group with SRB inoculation volume of 100 mL is the most obvious.