Factors affecting the heterotrophic nitrification property of heterotrophic nitrification-aerobic denitrifier

Based on the good denitrification effectiveness of heterotrophic nitrification-aerobic denitrifier H1,this paper investigated the metabolic pathways and the heterotrophic nitrification characteristics of H1 under different conditions including dissolved oxygen concentration,wastewater composition and the metal ions.The results showed that when the dissolved oxygen concentration was 4.7 mg/L in the simulated NH4+ wastewater,the removal pathway of ammonia was NH4+—→ NH2OH —→N2O—→N2,which was the fast removal pathway.In the simulated NH4+ and NO2 wastewater,NH4+-N was removed by short-cut nitrification and denitrification,not showing priority denitrification by H1 in the whole process.In the simulated NH4+ and NO3 wastewater,NO3 induced hydroxylamine oxidase to produce NO2-N,thus NH4+-N was removed by the nitrite levels of denitrification pathway.In the simulated NH4+ wastewater,1 mmol/L Cu2+and Fe2+ can significantly activate the activities of heterotrophic nitrification.