Simultaneous removal of high concentrations of ammonia nitrogen and calcium by the novel strain Paracoccus denitrificans AC-3 with good environmental adaptability.

The novel Paracoccus denitrificans AC-3 strain was isolated and displayed outstanding purification capability for high concentrations of ammonia nitrogen (NH-N) and calcium (Ca). Meanwhile, the strain exhibited excellent environmental adaptability within a wide pH range and high levels of NH-N and Ca. Nitrogen balance analysis demonstrated that the pathways of NH-N removal consisted of 80.12% assimilation and 16.60% heterotrophic nitrification aerobic denitrification (HNAD). In addition, Ca was removed by forming calcium carbonate (CaCO) with carbonate (CO) and bicarbonate (HCO). COand HCO were obtained from carbon dioxide (CO) hydration, which was catalyzed by carbonic anhydrase (CA) secreted by strain AC-3. The alkaline environment for carbonate precipitation was provided by CA and HNAD. The resulting CaCO existed in the form of calcite and exhibited a unique morphology and elemental composition.