[Characteristics of nitrite denitrification by Paracoccus shandongensis wg2 strain]

To address the issues of low efficiency and susceptibility to high-concentration pollutants in nitrite nitrogen (NO₂^--N) removal in existing technologies, screening functional bacterial strains with high NO₂^--N removal capacity has become one of the effective solutions. This study focused on a strain, Paracoccus shandongensis wg2, isolated from activated sludge in the wastewater of propylene oxide saponification, investigating its nitrogen removal mechanism through nitrogen balance analysis and isotopic tracing. The results demonstrated that the strain adopted a nitrogen removal metabolic pathway belonging to the nitrite denitrification type. Under anaerobic conditions, the strain exhibited remarkable nitrite nitrogen (NO₂^--N) removal efficiency, achieving over the elimination rate over 98.00% within 48 h. Through process parameter optimization, the optimal denitrification conditions were determined as follows: glucose as the carbon source, C/N ratio of 5, initial pH 7.0, temperature of 30 ℃, and rotation speed of 170 r/min. Under these optimized conditions, strain wg2 accomplished complete NO₂^--N (55 mg/L) removal within 10 h. This research not only provides a microbial resource for the biological treatment of nitrogen-containing wastewater but also offers significant practical guidance for addressing high-concentration nitrite wastewater.