Strain HG-7 was identified as Pseudomonas sp. through 16s rRNA gene sequence analysis. The aerobic denitrification ability of strain HG-7 was further proved by the existence of the napA and nirK genes. Further studies showed that the optimal carbon resources for strain HG-7 were sodium acetate and sodium succinate, the optimal C/N ratio was 6−10, and the suitable temperature was 26−30℃. At this condition, with an initial nitrate nitrogen of 100 mg/L, 98% of nitrate could be removed in 48 hours and the amount of nitrite accumulation was very small. Moreover, with nitrite as the sole nitrogen source, 100% of nitrite could be removed at lower nitrite concentration. But the nitrite nitrogen removal rate was about 40% when the nitrite concentration increased to 91.4 mg/L, indicating that high nitrite concentration was harmful for aerobic denitrification by strain HG-7. The strain HG-7 has great potential to be used for biological nitrogen removal, which was particularly significant for actual wastewater treatment processes.

Two Anaerobic Filter (AF)-Biological Aerated Filter (BAF) systems, one for bioaugmented system and another for control system, were set-up to treat coking wastewater, and the influence of the introduced nitrogenous heterocyclic compounds on the reactor performance was investigated. The results showed that the COD removal efficiency of AF in both bioaugmented and control system was 35% while the BOD₅/COD increased from 0.33 to 0.59 after the treatment of AF in both systems. When 100 mg/L carbazole was introduced to the influent, the COD removal efficiency of the bioaugmented AF remained 35% and BOD₅/COD of the bioaugmented AF effluent decreased to 0.53, while the COD removal efficiency of the control AF declined to 23% and BOD₅/COD of the control AF effluent dropped to 0.45. When 100 mg/L quinoline and 50 mg/L pyridine were introduced to the influent simultaneously, the COD removal efficiency of the bioaugmented AF decreased to 27% and BOD₅/COD of the bioaugmented AF effluent decreased to 0.48, while the COD removal efficiency of the control AF declined to 12% and BOD₅/COD of the control AF effluent decreased to 0.38. Moreover, the removal efficiencies of the introduced carbazole, quinolone and pyridine were 83%, 91% and 88% respectively after bioaugmented AF treatment, while the removal efficiencies of the introduced carbazole, quinolone and pyridine were 57%, 66% and 55% respectively after the control AF treatment. This indicated that the bioaugmented system was more effective to resist the impact of high concentration nitrogenous heterocyclic compounds. The GC-MS analysis of the bioangmented AF effluent indicated that the introduction of nitrogenous heterocyclic compounds led to an increment of the alkane and benzoic esters in the AF effluent. This study revealed the impact of the high concentration of organic compounds on A/O system for treating coking wastewater.