Effective removal of Mn(Ⅱ) from acidic wastewater using a novel acid tolerant fungi Aspergillus sp. MF1 via immobilization

Abstract

Biological processes based on the oxidation of Mn(II) are extensively favored. However, this is always limited by the low pH of wastewater. The biological removal of Mn(II) from acidic wastewater through immobilization technology is a promising approach owing to its high efficiency and low cost. However, the mechanism underlying Mn(II) removal by fungi remains unclear. In this study, a strain of acid-tolerant Aspergillus sp. MF1 screened from acid mine drainage (AMD), was used for immobilization. The results showed that polyvinyl alcohol (PVA), sodium alginate (SA), and zeolite were the best carrier materials, and the contents of CaCl2, PVA, SA, zeolite, and spore suspension were 4%, 6%, 2%, 4%, and 15%, respectively. The maximum Mn(II) removal efficiency achieved was 77.21%. Additionally, the analysis of subcellular distribution and chemical morphology demonstrated that Mn(II) removal was attributed to intracellular enrichment. The microspheres were reused for three cycles, and the removal efficiency of Mn(II) was guaranteed to exceed 60%. In summary, the immobilized Aspergillus sp. MF1 has stronger acid resistance and more effective treatment efficiency under high concentrations of Mn(II) compared to traditional biological processes, illustrating the excellent application prospects for Mn(II)-containing acidic wastewater.