Optimal conditions and nitrogen removal performance of aerobic denitrifier sp. pw-6 and its bioaugmented application in synthetic domestic wastewater treatment.

To assess the possibility of using aerobic denitrification (AD) bacteria with high NO-N accumulation for nitrogen removal in wastewater treatment, conditional optimization, as well as sole and mixed nitrogen source tests involving AD bacterium, sp. pw-6 was performed. The results showed that the optimal carbon source, pH, / ratio, rotational speed, and salinity for this strain were determined to be succinate, 7, 20, 160 rpm, and 0%, respectively. Further, this strain preferentially utilized NH-N, NO-N, and NO-N, and when NO-N was its sole nitrogen source, 92.28% of the NO-N (150 mg·L) was converted to NO-N. However, when NH-N and NO-N constituted the mixed nitrogen source, NO-N utilization by this strain was significantly lower ( < 0.05). Therefore, a strategy was proposed to combine pw-6 bacteria with traditional autotrophic nitrification to achieve the application of pw-6 bacteria in NH-N-containing wastewater treatment. Bioaugmented application experiments showed significantly higher NH-N removal (5.96 ± 0.94 mg·L·h) and lower NO-N accumulation (2.52 ± 0.18 mg·L·h) rates ( < 0.05) than those observed for the control test. Thus, AD bacteria with high NO-N accumulation can also be used for practical applications, providing a basis for expanding the selection range of AD strains for wastewater treatment.