Acid catalysis coupling bioleaching for enhancement of metals removal from waste resin powder

Metals removal from industrial process residues is essential to alleviate the potential threat to environment and avoid the resource waste. Because of very low concentration of metals and complexity of residues, conventional pyrometallurgical and hydrometallurgical routes suffer high cost and uncompleted removal. Here acid catalysis coupling bioleaching strategy was proposed for cost-efficient cleaning of metals from waste resin powder by applying double stress adapted consortium. The results showed that low pH bioleaching significantly improved the metals release, near 100% metals was leached out and no impurities of Fe(III)-precipitates was present in bioleached residue at pulp density of 10% and pH 0.7, which indicated the positive effects of acid in bioleaching of waste resin powder. Economic analysis exhibited that more profits of 33.7 $/t and 56.2 $/t residue were obtained respectively from metals recovery in case of pH 0.7 bioleaching compared with bioleaching at pH 1.5 and acid leaching at pH 0.7. Further stirring bioleaching and static leaching showed similar metals extraction rate under high pulp density conditions and TCLP tests indicated all bioleached residues could be reused as nonhazardous materials safely. However, static bioleaching showed higher ferric iron regeneration capacity and more stable community composition. These findings demonstrated that static low pH bioleaching might be more feasible for treatment of solid waste in full-scale applications from a technological and economical perspective.