Simultaneous removal of ammonia nitrogen and copper via nitrifying strain Bacillus megaterium based on...

Composite polluted wastewater (CPW) containing ammonium nitrogen (NH₄⁺-N) and Cu²⁺ discharged from industrial and agricultural activities poses severe threats to ecological environments and human health. Although nitrification and biomineralization technologies have been separately applied to the removal of NH₄⁺-N and Cu²⁺, nitrate accumulation was a potential drawback of the former, while high toxicity of Cu²⁺ may triggered bacterial denaturation in the latter treatment system. In the present study, Bacillus megaterium was used to simultaneously remove NH₄⁺-N and Cu²⁺ from CPW via heterotrophic nitrification-aerobic denitrification (HNAD) and microbially-induced phosphate precipitation (MIPP). Kinetic analyses revealed that the optimal cultivation conditions for Bacillus megaterium included an initial NH₄⁺ concentration of 100 mg/L, an initial Cu²⁺ concentration of 100 mg/L, and an initial pH of 7, with corresponding removal efficiencies of 99.7% for both NH₄⁺ and Cu²⁺. Microscopic characterizations demonstrated that the bacteria converted NH₄⁺ into N₂ through the HNAD process and simultaneously generated alkalinity required for the MIPP process, thereby removing Cu²⁺ via adsorption and coprecipitation. Furthermore, the removal of NH₄⁺ inhibited the formation of copper-ammonia complexes. This work provides a novel insight into the practical application of integrated HNAD and MIPP technologies for the simultaneous remediation of CPW co-contaminated with NH₄⁺-N and Cu²⁺.