Screening And Denitrification Characteristics Of Simultaneous Heterotrophic Nitrification And Aerobic Denitrification Bacteria

In this paper,the theory and technology of enhanced activated sludge simultaneous heterotrophic nitrification and aerobic denitrification were studied.Five strains capable of denitrifying by SND were isolated from activated sludge samples.The strains QU01,QU05 and QU08 belong to Bacillus,respectively.The strains QU02 and QU07 belong to Pseudomonas and Paracoccus respectively.The strains QU01,QU02,QU05,QU07 and QU08 are named Bacillus sp.QU01,Pseudomonas sp.QU02,Bacillus sp.05,Paracoccus sp.QU07 and Bacillus sp.QU08 selected SND denitrification strains Pseudomonas sp.QU02 and Paracoccus sp.QU07 with higher denitrification rate for in-depth study.The growth characteristics of strains Pseudomonas sp.QU02 and Paracoccus sp.QU07 were investigated.The optimum carbon sources were glucose and sucrose,the optimum initial pH of the medium was 9 and 8,and the optimum NaCI concentration was 15 and 5 g/L.Under the optimum conditions,the maximum growth of SND denitrification strains reached 13.8 and 27.9,respectively.The influencing factors of SND denitrification of the two strains were investigated,and the optimum denitrification of SND was found.Sodium succinate was used as organic carbon source,the optimal C/N for nitrogen removal was 10,the optimal initial pH for nitrogen removal matrix was 8 and 7,and the optimal NaCl concentration for nitrogen removal was 5 g/L.The SND denitrification process of strains Pseudomonas sp.QU02 and Paracoccus sp.QU07 under optimized conditions was characterized.After 72 hours of treatment,the denitrification rates reached 93.7%and 97.2%,respectively.High throughput sequencing analysis of activated sludge samples showed that dominant bacteria had no denitrification ability in the activated sludge system.SND denitrifying bacteria were added to the activated sludge for microbial enharicement.The enhanced samples showed good denitrification characteristics in three batches of simulated wastewater and printing and dyeing wastewater.Finally,the Ectoine concentration of Halomonas sp.B01,a moderate halophilic bacteria,growing and secreting at different salt concentrations was studied.The growth of SND denitrification strains was inhibited by high salinity,but Ectoine could assist the stress-resistant growth of SND denitrification strains.The combination of SND denitrification strains and Ectoine secreting strain Halomonas sp.B01 was applied to high-salt wastewater,and the denitrification rate reached 97.3%after 144 hours.And there is no accumulation of nitrate and nitrite in the whole denitrification process.