Microbial community analysis of simultaneous ammonium removal and Fe 3+ reduction at different influent ammonium concentrations.

This study investigates the impacts of influent ammonium concentrations on the microbial community in immobilized heterotrophic ammonium removal system. Klebsiella sp. FC61, the immobilized species, has the ability to perform simultaneous ammonium removal and Fe ³⁺ reduction. It was found that average ammonium removal rate decreased from 0.308 to 0.157 mg/L/h, as the influent NH ₄ ⁺ -N was reduced from 20 to 10 mg/L. Meanwhile, at a total Fe ³⁺ concentration of 20 mg/L, the average Fe ³⁺ reduction removal efficiency and rate decreased from 44.61% and 0.18 mg/L/h, to 27.10% and 0.11 mg/L/h, respectively. High-throughput sequencing was used to observe microbial communities in bioreactor Samples B1, B2, and B3, after exposure to different influent NH ₄ ⁺ -N conditions. Results show that higher influent NH ₄ ⁺ -N concentrations increased microbial richness and diversity and that Klebsiella sp. FC61 play a functional role in the simultaneous removal of NH ₄ ⁺ -N and Fe ³⁺ reduction in bioreactor systems.