好氧高温猪粪堆肥中重金属砷、铜、锌的形态变化及钝化剂的影响

Changes of heavy metals form during aerobic high temperature composting of pig manure and the effects of passivators

采用连续提取法研究了猪粪好氧堆肥处理中重金属浓度和形态的变化以及添加不同比例的重金属钝化剂对其浓度和形态的影响.结果表明:经过堆肥处理后,猪粪中重金属As、Cu和Zn的总浓度均有所增加.从重金属结合形态的变化来看,可交换态As和Zn含量降低,残渣态As和Zn含量升高,表明As和Zn存在着向有效性相对较低的形态转化的趋势;重金属Cu则表现出不同的变化趋势,即可交换态与残渣态Cu含量下降,而碳酸盐结合态、铁锰结合态及有机结合态Cu含量有所增加,在今后的堆肥利用中应注意其可能带来的环境风险;3种重金属钝化剂及不同添加比例的处理中,5.0%的海泡石和2.5%的膨润土分别对重金属As、Zn表现出较好的钝化效果,堆肥后残渣态As和Zn的增幅分别达到79.8%和158.6%,均高于不加钝化剂处理.与对照相比,堆肥后7.5%的海泡石对残渣态Cu的降低幅度最小,为39.3%.猪粪堆肥中添加适量的重金属钝化剂,可以在一定程度上降低重金属的有效性以及猪粪堆肥利用中重金属污染的风险.

Sequential extraction method was employed to study the heavy metals concentration andform change during aerobic high temperature compositing of pig manure,and the effects of amendment with different proportion of passivators on the concentration and form change.During the composting process,the concentrations of total As,Cu,and Zn in the manure all increased to some extent.As for the form change of the heavy metals,the exchangeable As and Zn decreased while theresidual As and Zn increased,indicating that the availability of As and Zn declined through thecomposting process.On the other hand,the exchangeable and residual Cu decreased while the car-bonate-,Fe /Mn-,and organic bound Cu increased,suggesting the potential environmental risk ofthe future application of the compost.Among the passivators amended,5.0% of sepiolite and2.5% of bentonite had the best effect in reducing the availability of As and Zn,with the residualform of As and Zn after composting increased by 79.8% and 158.6%,respectively,and 7.5% ofsepiolite induced the least decrement（39.3%） of residual Cu,compared with the control.There-fore,amendment with appropriate proportion of passivator during pig manure composting coulddecrease the availability of heavy metals in the manure,and reduce the environmental risk of applying the compost to farmland.