Study on the removal of Pb2+ by immobilized acid-resistant Aspergillus and its mechanism

Immobilized microorganism technology has been widely used in the field of heavy metal wastewater treatment due to its advantages of high treatment efficiency and low input cost. However，the related mechanism of heavy metal removal is still unclear. In this paper，a strain of acid-resistant Aspergillus sp. MF1 screened from acid mine drainage was used as the research object for immobilization treatment. Subcellular separation technology and five-step extraction method were used to preliminarily reveal the mechanism of Pb2+ removal from immobilized Aspergillus sp. MF1 through SEM and FTIR characterization. The results showed that under the condition of pH 3.5 and initial Pb2+ mass concentration 10 mg/L，the removal rate of Pb2+ could reach 78.26%. The removal mechanism of Pb2+ from immobilized Aspergillus sp. MF1 could be summarized into two aspects. On the one hand，it was attributed to high specific surface area of carrier and adsorption of Pb2+ by surface active groups of polyvinyl alcohol and sodium alginate. On the other hand，it was attributed the chelation，adsorption and ion exchange from cell wall，and the compartmentalization of vacuole and other organelles. In addition，immobilized Aspergillus sp. MF1 could be used continuously for 5 cycles，and the removal rate of Pb2+ could reach more than 30%，and no rupture or cell leakage occurred during the removal process.