How to Enhance the Partial Nitrification Process and Ammonia-Oxidizing Bacteria Growth Rate at Lower Temperature (13 ± 3°C)

The effects of an electric field on the partial nitrification process and growth rate of ammonia-oxidizing bacteria (AOB) to reduce lower temperature inhibition were investigated. The results showed that the electric field could dramatically enhance the AOB growth rate and amount even at 13 ± 3°C. The ammonia removal efficiency and effluent nitrite concentration of R1 (electric field) were significantly enhanced by 128.21% and 167.62% compared with R2 (control group). The relative abundance of AOB in R1 was 111.09% higher than in R2; meanwhile, the AOB amount of R1 was also 163.81% higher than in R2. Compared to AOB amount, the nitrite-oxidizing bacteria amount of R1 was 16.67% lower than that of R2, which also benefited the partial nitrification process. In addition, the electric field could enhance cell division by stimulating AOB metabolism and activity, accelerating ion migration rate and gene expression, further improving the AOB amount even at low temperature.