Denitrification Performance Of Heterotrotic Nitrification-Aerobic Denitrification Bacteria

Wastewater with high nitrogen cause serious environmental problem in China and high nitrogen is one of the most important factors of eutrophic waterbody and Malodorous Water. Biological nitrogen removal is consider as one of the most efficient methods to remove nitrogen in wastewater. Heterotrophic nitrification- aerobic denitrification bacteria were attracting increasingly interests due to their advantages in waste water. In this work, we screened four heterotrophic nitrification- aerobic denitrification bacteria from wastewater, landfill leachate and activated sludge named ws-1, ws-2, ws-6 and ws-7 respectively. Our work is focus on identification, studying characteristics of nitrification and denitrification in different nitrogen resource and exploring the result of nitrogen removal in eutrophic waterbody of bacteria.1. The strains ws-1, ws-6 and ws-7 were identified as Pseudomonas sp. and ws-2 as Agrobacterium sp. based on 16S rRNA gene sequence analysis, all the four strains were Gram negative bacteria. These bacteria could utilize ammonia, nitrate and nitrite as sole nitrogen resource, but there is huge difference in terms of nitrogen removal when NO3--N and NO2--N as the sole nitrogen source.2. The N transformation profiles of the strain ws-1 under aerobic conditions were evaluated with ammonium, nitrate and nitrite as the sole nitrogen source, respectively. After 84 h incubation,98.96%,56.42% and 87.48% of 106 mg/L NH4+-N, NO3--N and NO2--N was removed, respectively. N2 was the dominant product in all three bioconversion systems which occupied 52.33%,41.6% and 35.1% of initial N, respectively. The evidence that N2 production was later than nitrite consuming implied N2 was produced probably via hydroxylamine not nitrite. The final intracellular N concentration was extremely low and only occupied 9.85%,8.15% and 11.51% of initial NH4+-N, NO3--N and NO2--N, respectively. The strain ws-2 could remove 95.8% of ammonia within 44 h. N2, nitrate and intracellular nitrogen were three main products which accounted for 42.4%,23.8% and 19.4% of initial nitrogen, respectively. The strain could remove 80.5% of nitrate and 97.1% of nitrite, and the production of N2 and intracellular nitrogen accounted for 50.2%～ 51.0% and 17.0%～17.8% of initial nitrogen, respectively. The most probably nitrification pathway of strain ws-1 and ws-2 are NH4+-N�'NH3O�'NO2--N�'NO3--N and the Proposed denitrification pathway of these two strains are NO3--N�'NO2--N�'NH3O�'N2.3. The strain ws-2 was further applied in the eutrophic wastewater, and the result showed that the stain, fixed on the polyurethane foams under aeration conditions, removed the 84.3%,71.3%,94.7% and 55.8% of CODcr, total nitrogen, ammonia and total phosphorus, respectively, demonstrating its application potential in eutrophication water treatment.