Department of Environmental Engineering, Ocean University of China, Qingdao 266100, China.
J Hazard Mater. 2011 Aug 15;192(1):226-33. doi: 10.1016/j.jhazmat.2011.05.008. Epub 2011 May 27.
A linked microbial process comprising bioleaching with sulfate-oxidizing bacteria and bioprecipitation with sulfate-reducing bacteria operating sequentially was investigated to deeply remove contaminating metals from dredged sediment. The results showed that sediment bioleaching resulted in a sharp decrease in sediment pH from an initial pH ∼ 7.6 to pH ∼ 2.5 within 10-20 days, approximately 65% of the main heavy metals present (Zn+Cu+Cr) were solubilized, and most of the unsolubilized metals existed in residual form of sediment. The acidic leachate that resulted from sediment bioleaching was efficiently stripped of metal sulfates using a bioprecipitation reactor when challenged with influent as low as pH ∼ 3.7. More than 99% of Zn(2+), 99% of Cu(2+) and 90% of Cr(3+) were removed from the leachate, respectively, due to the formation of ZnS, Cu(2)S and CrOOH precipitates, as confirmed by SEM-EDS and XRD detection. It was also found that alkalization of bioleached sediment using Ca(OH)(2) excluded the risk of sediment re-acidification. The ability of the combined process developed in this study to deeply remove heavy metals in insoluble sulfides or hydroxides forms makes it particularly attractive for the treatment of different types of metal contaminants.
采用序批式硫酸盐还原菌-硫酸盐氧化菌联合生物浸出-生物沉淀工艺深度去除疏浚底泥中的重金属。结果表明，底泥生物浸出可使底泥 pH 值从初始的 7.6 左右在 10-20 天内迅速降至 2.5，约 65%的主要重金属（Zn+Cu+Cr）被浸出，大部分未浸出的金属以残渣态存在。生物浸出产生的酸性浸出液，当进水 pH 低至 3.7 左右时，可在生物沉淀反应器中有效地去除硫酸盐。由于 ZnS、Cu(2)S 和 CrOOH 沉淀的形成，浸出液中超过 99%的 Zn(2+)、99%的 Cu(2+)和 90%的 Cr(3+)被去除，这一点通过 SEM-EDS 和 XRD 检测得到了证实。此外，用 Ca(OH)(2)对生物浸出后的底泥进行碱化处理可排除底泥再酸化的风险。该研究开发的联合工艺能够深度去除难溶性硫化物或氢氧化物形态的重金属，对于处理不同类型的金属污染物具有特别的吸引力。
