废旧镍镉电池的生物沥滤处理——沥滤停留时间的影响研究

Effect of contacting time on bioleaching of spent nickel cadmium batteries

用污泥加硫酸化液沥滤镍镉电池中的重金属是一种全新的工艺,该工艺主要由生物酸化反应器和金属沥滤反应器两个反应器组成。生物酸化反应器中产生的酸液就是沥滤电池中重金属的反应液。研究表明,酸化液在沥滤反应池的停留时间对沥滤的效果有显著影响。在1、4、7、12 d 4个停留时间中,4 d的效果是最好的,对金属Cd和Ni都用40 d左右基本实现了全部滤除;1d略微慢一些,Cd用了40 d,Ni用了45 d;7 d和12 d的沥滤时间都长于50 d。4 d产生的金属废液量是1 d的1/4,考虑到后续处理金属沥滤废液的工作量,选择4 d的停留时间要优于1 d。

An innovative bioleaching process was employed for treatment of spent nickel cadmium batteries. Activated sludge was first acclimated for oxidation of elemental sulfur to at a pH of 2.0. The acclimated activated was used to seed a bioreactor for converting sulfur in the feed to sulfuric acid at a hydraulic retention time of 4 days; the acidic effluent （pH = .1.86） was fed to a bioleaching reactor which contained cathodes and anodes from 8 Ni-Cd batteries. The effect of contacting time on the bioleaching reactor performance was determined using data on concentrations of Ni, Cd and living bacteria of the effluent samples taken when it was operating at a hydraulic retention time （HRT） of 1 d, 4 d, 7 d, and 12 d, The 4 d HRT treatment was most effective as it completed Ni and Cd leaching in the shortest period of time （40 d） with the least amount of effluent produced. Post treatment by precipitation at a pH of 11 resulted in a final effluent with 0.01 mg Ni and 0.05 mg Cd/L.