Cyclic biomineralization by incorporating iron-oxidizing and sulfate-reducing microorganisms for sustainable iron removal and sulfur recovery from acid mine drainage: Efficiency and mechanism

• Cyclic biomineralization-reduction strategy for simulated AMD treatment. • The biogenic sulfide could effectively reduce Fe 3+ with the formation of Fe 2+ and S 0 . • Successive biomineralization–reduction cycles achieved 89% of iron removal from AMD. • Biomineralization pretreatment reduced lime consumption and minimized sludge volume. • Integrated validation for iron removal and sulfur recovery from sulfate-rich AMD. The management of acid mine drainage (AMD) remains a global challenge faced by mining industry due to its severe environmental impact. Cyclic biomineralization has emerged as a promising method for the iron removal, but its application is constrained by the lack of efficient strategies for the residual Fe 3+ reduction to sustain the cyclic process. Herein, a novel cyclic biomineralization strategy that incorporates iron-oxidizing and sulfate-reducing microorganisms was proposed to achieve sustainable iron removal and sulfur recovery. The final removal efficiency of iron ions reached 89.35% after three cycles biomineralization treatment with Na 2 S as the Fe 3+ reducing agent, and 27.6% of the sulfate was removed simultaneously. Jarosite was identified as the main phase of the biomineralization sludge, and sulfur was formed as the oxidation product of S 2- . Moreover, biogenic sulfide produced in the sulfate reduction process effectively substituted for Na 2 S in the Fe 3+ reduction process, simultaneously producing sulfur as a recoverable by-product. After the cyclic biomineralization treatment, lime consumption for neutralization was reduced by 63.6% and the volume of sludge decreased by 70.1%. This work provides a promising integrated approach for the sustainable treatment of acid mine drainage, with efficient iron removal and sulfur recovery, being environmentally friendly and reducing the cost of neutralization.