Removal of iron, manganese and ammonium from contaminated mine water by biochar immobilized Acinetobacter sp. AL-6 under acid condition, and the role of extracellular polymeric substances

In acidic mine wastewater, Mn and Fe are among the prime heavy metals and pose a great threat to the ecological environment and human health. Combining biological and physical methods to treat heavy metal contaminated water bodies is a promising remediation technique. In this study, grapefruit peel biochar immobilized Acinetobacter sp. AL-6 (co-system) was applied to treat the contaminated water with co-existing Mn2+, Fe2+ and NH4+-N. The results showed that almost 100% of Mn2+, Fe2+, Zn2+ and Cu2+ were removed in bioreactor, and was transferred to Mn2+, Fe3+, Zn2+ and Cu2+ precipitates on the surface of co-system without N2O accumulation. Especially, Mn2+ and Fe2+ were adsorbed in extracellular polymers (EPS) of strain AL-6. The present study mainly confirmed that the combined system of biochar and bacteria had great potential in the complex water removal of multiple heavy metals and NH4+-N, and also revealed the regulation of heavy metals by the EPS of strain.