Influence of Free Ammonia Concentration on Heterotrophic Nitrification—Aerobic Denitrification Process by Strain Pseudomonas otitidis YM-01

Pseudomonas otitidis YM-01, which was isolated from swine wastewater, showed efficient simultaneous nitrification and denitrification ability by effectively using a single nitrogen source and a mixed nitrogen source. A high concentration of free ammonia (FA) can decompose EPS (extracellular polymeric substances), which makes the ammonia monooxygenase (AMO), hydroxylamine oxidase (HAO), periplasmic nitrate reductase (Nap), and nitrite reductase (NIR) lose the protective activity of EPS, resulting in the deterioration of the denitrification performance of the strain. For high-strength ammonium wastewater (500 mg/L and 1000 mg/L) with FA concentrations of 55 mg/L and 209 mg/L, the removal rates of strain YM-01 were 70.24% and 27.84%, respectively. The results indicate that strain YM-01 has the potential for application in high-strength ammonium wastewater.