科研之友
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摘要
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.
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