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Heavy metal distribution and speciation during sludge reduction using aquatic worms
- Zhang, Xiaoqi, Tian, Yu, Wang, Qiang, Chen, Lin, Wang, Xin
- Bioresource technology 2012 v.126 pp. 41-47
- Limnodrilus hoffmeisteri, heavy metals, predation, sewage sludge
- Changes in heavy metal distribution and speciation during the reduction of sewage sludge with the worm, Limnodrilus hoffmeisteri were assessed. In sludge containing 108.3±2.2, 455.5±10.3, and 39.4±1.8mg/kg of Cu, Zn, and Pb, respectively, more than 81% of these metals remained in the sludge after predation by the worms, while 4.1–9.7% of these metals were released into the liquid. The maximum uptake values of Cu, Zn, and Pb by the worms reached 180.5, 587.4, and 55.8mg/kg, respectively. The predation did not increase metal bioavailability in the final sludge as reflected by a 9.5–12.5% decrease in labile Cu and unchanged levels in labile Zn and Pb. The sewage sludge reduction efficiency of L. hoffmeisteri was 27.6–29.2%. These results indicated the relatively moderate changes in speciation and distribution of Cu, Zn, and Pb and the stable performance of worms in reducing sewage sludge.