Heterotrophic nitrifying and aerobic denitrifying bacteria that have been widely isolated from complicated activated sludge microflorae demonstrate dominant advantages in simultaneous removal of ammonium and nitrogen oxides under aerobic conditions. However, owing to the need of organic carbon to support bacterial growth, nitrogen removal of actual industrial wastewater with low carbon-to-nitrogen (C/N) ratio remains a challenge. Here, Pseudomonas mendocina Y7 was identified and presented to effectively remove nitrogen of actual refinery wastewater with low C/N ratio. The isolated bacterium showed high removal efficiency of ${\text{NH}}_4^{+}$–N, ${\text{NO}}_2^{-}$–N, and ${\text{NO}}_3^{-}$–N up to about 90% in single (100 mg/L) or mixed (200 mg/L) nitrogen source media at low C/N ratio of 6 when it was cultivated for 12 or 21 h. According to PCR amplification, the heterotrophic nitrification and aerobic denitrification capability of strain Y7 was attributed to the functional genes of amoA, hao, napA, and nirS. In activated sludge process for treating actual refinery wastewater with low C/N ratio, compared to abundant accumulation of ${\text{NO}}_2^{-}$–N and ${\text{NO}}_3^{-}$–N only using the activated sludge, strain Y7 significantly improved the removal efficiency of ${\text{NH}}_4^{+}$‒N and total nitrogen (with influent concentrations of about 40 and 55 mg/L) from about 47% and 22% to about 85% and 73%, respectively, without the accumulation of nitrogen oxides. Microbial community structure analysis revealed that strain Y7 could coexist well with other microorganisms in the activated sludge and maintain highly efficient and steady nitrogen removal in continuous treatment system. This discovery provides a promising treatment approach toward actual nitrogen-rich industrial wastewater.

从复杂的活性污泥微生物群中广泛分离出来的异养硝化和好氧反硝化细菌在好氧条件下同时去除铵和氮氧化物方面表现出显着优势。然而，由于需要有机碳来支持细菌生长，以低碳氮 (C/N) 比去除实际工业废水仍然是一个挑战。在这里，鉴定并展示了Pseudomonas mendocina Y7，以有效去除低 C/N 比的实际炼油厂废水中的氮。分离的细菌显示出高去除率${\text{NH}}_4^{+}$-N， ${\text{不}}_2^{-}$-N，和 ${\text{不}}_3^{-}$– 在单一 (100 mg/L) 或混合 (200 mg/L) 氮源培养基中，在低 C/N 比为 6 的情况下培养 12 或 21 小时时，N 高达约 90%。根据PCR扩增，异养硝化和应变Y7的好氧反硝化能力归因于的功能基因AMOA，豪，的napA，和NIRS。在处理实际炼油厂废水的活性污泥工艺中，C/N 比低，与大量积累相比${\text{不}}_2^{-}$–N 和 ${\text{不}}_3^{-}$-N 仅使用活性污泥，菌株 Y7 显着提高了 ${\text{NH}}_4^{+}$‒ 氮和总氮（进水浓度约为 40 和 55 毫克/升）分别从约 47% 和 22% 增加到约 85% 和 73%，而没有氮氧化物的积累。微生物群落结构分析表明，菌株Y7可以与活性污泥中的其他微生物良好共存，并在连续处理系统中保持高效稳定的脱氮。这一发现为实际的富氮工业废水提供了一种有前景的处理方法。