Valuable Metal Recovery During the Bioremediation of Acidic Mine Drainage Using Sulfate Reducing Straw Bioremediation System

Abstract

Recovery of valuable metals from acidic mine drainage (AMD) during bioremediation using straw bioremediation system was investigated, with observation of efficient metal recovery. The recovery loading rates of Cu and Zn were 46.19 ± 6.13 and 43.86 ± 6.76 mg m−3 h−1, respectively. More than 97.0% of Cu and more than 87.0% of Zn were recovered from AMD during bioremediation. The recovery loading rate of Cu increased by 4.54 mg m−3 h−1 for each 1 mg L−1 increase in influent concentration while that of Zn increased by 4.08 mg m−3 h−1. Heavy metal toxic effect on the metal recovery in the straw bioremediation system could be neglected in most cases. Low pH could severely decrease recovery rate of Zn, while it had no influence on that of Cu. The recovery loading rate of Zn decreased by almost 70% when the influent pH decreased from 7.0 to 3.0. Cu could be recovered efficiently even at a short hydraulic residence time (HRT) of 18 h, while Zn could only be efficiently recovered at a relatively long HRT of 80 h, indicating that selective metal recovery might be achieved with relatively short HRT and bioreactor process optimization. These findings suggested the feasibility of using sulfate-reducing straw bioremediation system to recover valuable metals during bioremediation of AMD.