Preparation of a novel algae-fungal immobilized bioparticle and its treatment study of Mn(II) and Zn(II) in acid mine drainage

Acid mine drainage (AMD) contains high levels of harmful heavy metal (HM) ions. To mitigate its harmful effects, this study developed novel Algae-Fungal Immobilized Bioparticles (AFIBs) using Chlorella ellipsoidea HLDA2 and Aspergillus tubingensis HLDF3. By optimizing the culture conditions of the algal-fungal system, the immobilization efficiency of the mycelial pellets formed at pH 3 reached 94.40 %. It was revealed that AFIBs effectively removed Mn(II) and Zn(II) through the mechanisms of electrostatic adsorption, ion exchange, chelation, and chemical precipitation. AFIBs outperformed both single algae and fungal systems within the Mn(II) and Zn(II) concentration range of 1 to 30 mg/L tested. The water quality index ( WQI ) of the treated AMD with AFIBs was 82.82, indicating suitability for aquatic life. In the real AMD treatment, the AFIBs decreased Mn(II) and Zn(II) concentrations to 1.832 mg/L and 1.663 mg/L, respectively, achieving removal rates of 92.97 % and 87.40 %. They also raised the pH to 8.59, adhering to the coal industry pollutant discharge standards (GB20426–2006). Thus, the novel AFIBs developed offer a sustainable solution for AMD remediation.