| Heterotrophic nitrification and aerobic denitrification (HN-AD) technology has drawn lots of attention due to its characteristics of simultaneous removal of carbon and nitrogen. Recently, bisphenols (BPs) as endocrine disrupters exist in various water because of their wide application. To realize the effective removals of ammonia, nitrate and bisphenols, in this paper a HN-AD bacterial consortium capable of degrading various BPs was enriched, and then a bacterium was isolated and identified as Pseudomonas sp. ZH-FAD. Bisphenol F (BPF) was used as a typical compound and the characterization of BPF degradation and nitrogen removal by the enriched consortium and strain ZH-FAD were investigated. These studies provide the theoretical basis for the application of HN-AD technology.Nitrogen removal by the BPs-degrading bacterial consortium was investigated. The experimental results showed that the bacterial consortium was capable of degrading various BPs including BPF, bisphenol A (BPA),4,4'-dihydroxy-benzophenon (DHBP) and 4,4'-thiodiphenol (TDP). Among these compounds, the bacterial consortium could degrade BPF up to 372.94 mg/L. When pH, temperature and shaking speed ranges were 7.0-9.0,30-35? and 100-200 rpm, respectively, the bacterial consortium had high BPF degradation activity. BPF degradation products were detected using HPLC and GC-MS. The main metabolites were bis(4-hydroxyphenyl)methanol, DHBP,4-hydroxyphenyl-4-hydroxybenzoate and 1,4-hydroquinone. Based on these metabolites, degradation pathway of BPF was proposed. When BPF and NH4+-N were used as sole carbon and nitrogen sources (C/N?11), respectively, NH4+-N could be completely removed, only trace NO2--N was accumulated and completely removed in the end. In addition, the bacterial consortium could achieve simultaneous BPF degradation and nitrogen removal by utilizing NO3--N and NO2--N as sole nitrogen sources, respectively. Further analysis showed that nitrogen removal could be achieved via HN-AD process and 60.7% of initial NH4+-N was transformed to gaseous products including N2. Clone library analysis showed that the consortium was mainly composed of four bacterial species including Salmonella enterica (46.4%), Enterobacter (28.6%), Citrobacter (21.4%) and Pseudomonas (3.6%). These species could cooperate to simultaneously degrade BPF and remove nitrogen. Some species in the bacterial consortium are propably capable of simultaneous nitrification, aerobic denitrification and BPF degradation.Pseudomonas sp. ZH-FAD, which was isolated from the enriched consortium, was capable of simultaneous BPF degradation and NO3--N removal by utilizing them as sole carbon and nitrogen sources. The optimal removal conditions were 35?,100-150 rpm, pH 7.0. The shaking speed had the most significantly influence on BPF degradation and nitrogen removal by strain ZH-FAD. The C/N ratio experiment with the same initial NO3--N concentration showed that strain ZH-FAD could tolerate and degrade BPF up to 400 mg/L and achieved the highest BPF degradation rate at 300 mg/L. The growth of strain ZH-FAD was inhibited with the increase of BPF concentration, resulted in the decreased nitrogen removal rate; higher NO3--N removal rate could be achieved under higher C/N ratio conditions. Especially, NO3--N could be completely removed while C/N ratio was over 15. The C/N ratio experiment with the same initial BPF concentration showed that BPF degradation rate was less affected by different C/N ratio. High NO3--N removal could be achieved under high C/N ratio (?15) while NO3--N and BPF were removed more rapidly under lower C/N ratio (<10). During the above processes, less NO2--N was accumulated under high C/N ratio conditions. In a word, BPF and NO3--N could be simultaneous removed efficiently when C/N ratio was 15. Nitrogen balance analysis under the optimal conditions showed that 34.0% of 15.6 mg/L initial NO3--N was converted to be gases products. |
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