生活垃圾与植物废弃物混合堆肥过程重金属的形态变化

Changes of Heavy Metal Speciation during Composting of Mixed Domestic Waste and Plantation Waste

中试规模条件下,以有机生活垃圾与植物废弃物为原料,考察堆肥过程重金属形态变化。结果表明:重金属Pb、Cd和Zn由其它形态向Fe-Mn结合态转化,堆肥结束时,Fe-Mn结合态分别占各自总量的56.0%、48.7%和64.1%;残渣态的Ni向有机结合态和Fe-Mn结合态转化,堆肥结束时,Ni主要以残渣态和有机结合态存在;Cu和Cr主要以残渣态存在,分别占各自总量的64.9%和77.5%。堆肥会使重金属Pb、Ni、Cu和Zn的生物有效性略微增加,而Cr的生物有效性则出现了下降。源分类收集垃圾堆肥样中各种重金属含量均低于混合收集垃圾堆肥样,说明采用源分类方式收集生活垃圾进行堆肥处理,可有效控制堆肥产品中的重金属含量。

Evolution of heavy metal speciation was monitored during co-composting process of organic fraction of domestic waste and plantation waste in a pilot-scale composting plant.The results showed that the contents of Fe-Mn bound fraction for Pb, Cd, Zn increased during composting and about 56.0%, 48.7%, 64.1% of which existed as Fe-Mn bound fraction respectively in the final compost product.The content of residual fraction for Ni decreased while that of Fe-Mn bound fraction and organic fraction increased during composting, and Ni mainly existed in forms of organic fraction and residual fraction in the final compost product.For Cu and Cr, about 64.9% and 77.5% of them were associated with residual fraction respectively.The bioavailability of Pb, Ni, Cu, and Zn increased while bioavailability of Cr decreased after composting.Compared to the mixed waste compost, heavy metal contents in the compost using source separated waste as materials were relatively lower, indicating that source separation of compostable materials benefits to control contents of heavy metal in compost product.