生物炭添加对猪粪菌渣堆肥过程中Cu、Zn的钝化作用

为探讨生物炭对猪粪堆肥过程中重金属钝化效果的影响,利用强制通风静态堆肥技术研究不同生物炭添加量对猪粪菌渣好氧堆肥发酵效果及重金属Cu、Zn形态的影响。结果表明:与未添加生物炭堆肥处理相比,添加生物炭处理提高堆肥pH值0.2～0.3个单位,至堆肥结束时提高堆肥含水率15.6%～20.0%。添加生物炭改善了通气条件、pH、含水率等堆肥性质,加速了堆肥进程,其中6%和9%生物炭添加处理高温持续期显著高于未添加生物炭处理。堆肥处理后,猪粪、菌渣等混合物料中交换态Cu、Zn含量分别下降了4.25%～12.06%和2.83%～20.87%;堆肥处理能促进堆肥中Zn、Cu的形态向活性低的方向转化,降低重金属的生物有效性。堆肥物料中适量添加花生壳生物炭可提高对重金属Cu、Zn的钝化作用,其中6%生物炭添加处理对重金属Cu、Zn的钝化效果最好,分别为18.84%和11.55%。适量添加生物炭可加速猪粪菌渣堆肥进程和降低堆肥中Cu、Zn有效性,其中以6%生物炭添加量的钝化效果最好。

Passivating effect of biochar on heavy metals(Cu and Zn)during composting of pig manure and mushroom residues

With the rapid development of animal husbandry in China, the proportion of large-scale farms is increasing. Simultaneously, animal manure has largely been produced. Reusing animal manure as a resource and reducing its environmental adverse impact, are problems that need to be solved urgently. To explore the influence of biochar on the passivation effect of heavy metals during manure composting process, a series of composting tests were conducted to study the effect of different biochar applications on the status of heavy metals by using static forced-air composting boxes. The results showed that compared with the traditional compost control, the pH values of the composts with different biochar application increased by 0.2 to 0.3 pH units, and that the moisture contents of them increased by 15.6% to 20.0% at the end of the composting. It indicated that the addition of biochar improved the physiochemical characteristics of mixtures, such as the ventilation conditions, pH and the moisture content, and accelerated the composting process. The high-temperature durations of the treatments with 6% and 9% biochar application by weight were significantly higher than that of the treatment without biochar application. After aerobic composting with biochar, the concentrations of exchangeable Cu and Zn in the mixtures of pig manure and mushroom residues decreased by 4.25% to 12.06% and 2.83% to 20.87%, respectively. Moderate rate of biochar application could improve the passivation effect on Cu and Zn. The best estimated passivation effects on Cu and Zn were 18.84% and 11.55%, respectively, with 6% biochar application. These results suggest that the appropriate application of biochar can accelerate the composting process of pig manure and mushroom residues and reduce the effectiveness of Cu and Zn in composts.