沼渣混合物料堆肥处理对重金属形态的影响

Influence of co-composting treatment of anaerobic digested residue on the morphologicalvariation of heavy metals

通过室内模拟堆肥试验研究沼渣、猪粪、鸡粪混合堆肥过程中As、Cr、Cu、Pb、Zn形态和生物有效性的变化。结果表明,1)由于"相对浓缩效应",堆肥后As、Cr、Cu、Pb、Zn总量均有不同程度增加。2)堆肥后As的有机结合态比例升高了6.39%～7.01%;铁锰氧化物结合态Cr向有机结合态和残渣态转化,Cr的有机结合态和残渣态比例分别升高了3.35%～4.90%和7.50%～9.89%;Cu的铁锰氧化物结合态比例升高了3.22%～4.27%;Pb的残渣态比例升高了19.35%～22.54%;Zn的铁锰氧化物结合态比例升高了11.30%～11.83%。3)堆肥后As、Cr、Pb的生物有效性降低,Cu、Zn的生物有效性升高,其生物有效性从高到低排序为Zn、As、Pb、Cu、Cr。4)添加菌剂增强了堆肥处理对As、Cr、Cu、Pb、Zn的"相对浓缩效应",且在生物有效性方面对5种重金属有一定的钝化效果,尤其是对As和Pb。研究表明,堆肥处理不能降低堆肥体系中重金属总量,但可改变其生物有效性;添加菌剂能强化堆肥处理对重金属的影响。

This paper is engaged in the study of the influence of co-composting treatment of the anaerobic digested residue on the morphological variation of heavy metals. To be exact, we have explored the variations of form and bioavailability of As, Cr, Cu, Pb, Zn during the co-composting process of anaerobic digestion residue, pig manure and chicken manure through room-conditioned simulated composting experiment. The purpose of this paper is to provide a reference to reducing the hazards of resource utilization of anaerobic digestion residue. The results of our experiments show that： （1） Due to the ＂comparatively concentrated effect＂, the total amount of As, Cr, Cu, Pb, Zn tends to increase in different percentages after composting. （2） When the five fractions of As distribute evenly during the composting treatment, the organic fraction of As is expected to increase by 6.39%-7.01%. However, when the fraction of Fe-Mn oxide of Cr decreases, the Cr organic fraction and residual fraction tends to increase, whose organic fraction and residual fraction can be expected to increase by 3.35%-4.90% and 7.50%-9.89%, respectively. Fe-Mn oxide fraction of Cu tends to increase a bit by 3.22%-4.27%. At the same time, the residual fraction of Pb may significantly increase by 19.35%-22.54%, whereas Fe-Mn oxide fraction of Zn is expected to increase by 11.30%-11.83%. （3） The bioavailability of As, Cr and Pb would decrease while the bioavailability of Cu and Zn may increase after composting, their bioavailability stands in the following order： Zn〉As〉Pb〉Cu〉Cr. （4） The inoculating microbial strains tends to enhance the ＂relatively concentrated effect＂ of composting to As, Cr, Cu, Pb, Zn, enjoying a certain extent of passivation effect on the bioavailability of the five heavy metals, especially for As and Pb. The simulation experiment results demonstrate that, no significant variations were found for the total amount of heavy metals in the composting process. However, it is possible for heavy metals to change their bioavailability via composting. In addition, the inoculating microbial strains have been found to enhance the effect of composting on heavy metals. However, much has remained to be further studied as to the passivation mechanism of complex microbial strains on heavy metals in composting.