Graduate School of Science and Technology, Niigata University, Niigata 950-2181, Japan.
Bioinorg Chem Appl. 2012;2012:173819. doi: 10.1155/2012/173819. Epub 2012 May 27.
In order to investigate the behavior, distribution, and characteristics of heavy metals including rare earth elements (REEs), thorium (Th), and uranium (U) in sludge, the total and fractional concentrations of these elements in sludge collected from an industry water treatment plant were determined and compared with those in natural soil. In addition, the removal/recovery process of heavy metals (Pb, Cr, and Ni) from the polluted sludge was studied with biosurfactant (saponin and sophorolipid) elution by batch and column experiments to evaluate the efficiency of biosurfactant for the removal of heavy metals. Consequently, the following matters have been largely clarified. (1) Heavy metallic elements in sludge have generally larger concentrations and exist as more unstable fraction than those in natural soil. (2) Nonionic saponin including carboxyl group is more efficient than sophorolipid for the removal of heavy metals in polluted sludge. Saponin has selectivity for the mobilization of heavy metals and mainly reacts with heavy metals in F3 (the fraction bound to carbonates) and F5 (the fraction bound to Fe-Mn oxides). (3) The recovery efficiency of heavy metals (Pb, Ni, and Cr) reached about 90-100% using a precipitation method with alkaline solution.
为了研究包括稀土元素（REEs）、钍（Th）和铀（U）在内的重金属在污泥中的行为、分布和特性，测定了取自工业水处理厂的污泥中这些元素的总量和形态浓度，并与天然土壤中的相应浓度进行了比较。此外，还通过批式和柱式实验用生物表面活性剂（皂素和槐糖脂）洗脱研究了从污染污泥中去除/回收重金属（Pb、Cr 和 Ni）的过程，以评估生物表面活性剂去除重金属的效率。结果，大体上澄清了以下事项。（1）污泥中的重金属元素通常具有更高的浓度，且以比天然土壤更不稳定的形态存在。（2）带羧基的非离子型皂素比槐糖脂更有效地去除污染污泥中的重金属。皂素对重金属的迁移具有选择性，主要与 F3（与碳酸盐结合的部分）和 F5（与 Fe-Mn 氧化物结合的部分）中的重金属发生反应。（3）使用碱性溶液的沉淀法，重金属（Pb、Ni 和 Cr）的回收效率达到约 90-100%。
