生物炭对污泥堆肥及其利用过程重金属有效态的影响

以城市脱水污泥为研究对象,设置2种处理(A组:添加水稻生物炭; B组:未添加生物炭)进行污泥堆肥,并将污泥堆肥产品进行土地利用,研究污泥堆肥及其利用过程重金属(Cd、Pb、Cu、Zn、Ni)的变化特征及其钝化效果,同时考察添加生物炭的影响作用.结果表明:在污泥堆肥及其短期利用过程中,除Ni外,重金属总量没有显著变化,水稻生物炭对5种重金属总量的影响也不显著.污泥堆肥过程对5种重金属具有一定钝化作用,添加生物炭能显著降低重金属有效态含量,并具有显著的钝化效果(P 0. 05),钝化率达到16. 39%～43. 10%,其中Zn、Ni的钝化效果更为显著;而未添加生物炭的污泥堆肥过程对重金属有效态的钝化效果不显著(P 0. 05).施用污泥堆肥会增加土壤重金属含量,短期内,生物炭对污泥堆肥土壤利用后的重金属有效态具有一定影响,但效果不显著.

Effect of Biochar on Available Heavy Metals During Sewage Sludge Composting and Land Application of Compost

The effects of biochar addition to compost on change characteristics and passivation effect of heavy metals (Cd, Pb, Cu, Zn, Ni) were investigated during the process of sludge composting with two different composts (group A:with biochar; group B:without biochar) and land application of compost. The results indicated that the total amount of heavy metals (except Ni) did not change significantly during the process of sludge composting and land application of compost. Additionally, biochar addition had little effect on the total amount of heavy metals. During the sludge composting process, five heavy metals (Cd, Pb, Cu, Zn, Ni) were passivated. Sludge composting with the addition of biochar can decrease the available contents of heavy metals, and the passivation effect of heavy metals was significant (P<0.05). The passivation rate of the five examined heavy metals (Cd, Pb, Cu, Zn, Ni)ranged from 16.39%-43.10%, and the passivation effect for Zn and Ni was more significant. However, the passivation effect was not significant in the sludge composting process without the addition of biochar (P>0.05). The concentrations of heavy metals in soil increased with the application of sewage sludge compost products. In the short term, biochar had a certain passivation effect on the available heavy metals in soils with sludge compost application, but the effect was not significant.