蚯蚓黏液联合竹炭堆肥对污泥中重金属的影响

Effects of earthworm mucus combined with bamboo charcoal on heavy metals in sludge

重金属积聚于生活污泥中限制了其利用价值,为削弱污泥中重金属有效性和提升其可利用性,向污泥中添加蚯蚓黏液和不同比例竹炭(2%、4%、6%和8%),以污泥单独堆肥为对照组,探究黏液联合竹炭对堆肥后污泥的理化性质和重金属行为的影响。结果表明,相比污泥单独堆肥,添加黏液提升了污泥pH、电导率(EC)和降低了总氮(TN)、总磷(TP),添加竹炭后,污泥弱酸性环境进一步改善,有机质(OM)和EC提高,但营养元素仍存在一定流失。在单独黏液堆肥时,重金属总量(Pb、Ni、Cu、Zn和Cd)降低,Pb、Ni、Cd的交换态和碳酸盐结合态向残渣态转化,降低其有效性,随着污泥中添加黏液和不同比例竹炭,重金属总量进一步降低,Pb、Ni、Zn交换态和碳酸盐结合态逐渐向残渣态转化,而Cu有机结合态逐渐向交换态、碳酸盐结合态和残渣态转化,降低Pb、Ni、Zn和升高Cu的有效性。通过相关、回归和主成分分析可知,黏液联合竹炭主要改变EC和OM,分别影响污泥中有效Cu和有效Zn、Pb、Ni。黏液+8%竹炭处理在降低污泥中多数重金属有效性的效果最为显著。

The enrichment of heavy metals in domestic sludge limits its utilization.In order to reduce the availability of heavy metals and enhance the utility of the sludge,earthworm mucus and bamboo charcoal(2%,4%,6%and 8%)were added to sludge,and sludge composted alone was used as a control group.The physicochemical properties and heavy metals behavior of the sludge in different treatments were investigated during the composting.The results indicated that the addition of mucus enhanced sludge pH and conductivity,and also reduced the total nitrogen and total phosphorus compared to the sludge composted alone.The addition of bamboo charcoal to the mucus further improved the weak acidic environment of the sludge and increased the organic matter and conductivity,but some nutrients were lost during the composting as well.In the control treatment,the total heavy metals(Pb,Ni,Cu,Zn,and Cd)were decreased,and the exchange and carbonate bound Pb,Ni,and Cd were converted into the residue form,thus reducing the heavy metals availability.With increasing addition of bamboo charcoal to the mucus,the total heavy metals were further reduced and the exchange and carbonate bound Pb,Ni,and Zn were gradually shifted into the residue form,while organic bound Cu gradually transformed into the exchange from,carbonate bound,and residue form.This reduced Pb,Ni,and Zn availability and elevated Cu availability.The correlation,regression,and principal component analysis showed that mucilage combined with bamboo charcoal mainly changed EC and OM to affect Cu availability and Zn,Pb,and Ni availability in the sludge,respectively.Mucus+8%bamboo charcoal had the most significant effect in reducing most of the heavy metals availability in the sludge.