| At present,traditional nitrogen removal process during wastewater treatment usually exhibits the complex procedure and low efficiency.To solve these problems,the heterotrophic nitrification biological nitrogen removal has become one of the hotspots in the field of wastewater denitrification due to its rapid growth rate,wide proliferation substrate,strong environmental adaptability and aerobic denitrification ability.The research on heterotrophic nitrifying bacteria was mainly focused on the identification and nitrification characteristics of the new species,while the research on the bioaugmentation of heterotrophic nitrifying bacteria was lacking.Three heterotrophic nitrifying aerobic denitrifying bacteria of different species were used to construct the heterotrophic nitrifying compound bacteria YM.Meanwhile,the characteristics of heterotrophic nitrification-aerobic denitrificaton characteristics was studied by single factor test,the bioaugmentation efficiency of ammonia-rich organic wastewater by compound bacteria YM and the effect of bioaugmentation on sludge community structure by high-throughput sequencing technique were investigated.The research will provides the theoretical basis for the application of heterotrophic nitrifying bacteria to strengthen the practical engineering,especially for the current lack of cost-effective treatment for high pollutant concentration wastewater.The main results are as follows:(1)The heterotrophic nitrifying compound bacteria YM,which was constructed by three highly heterotrophic nitrifying bacteria,was more resistant to high concentration of ammonia nitrogen;more adaptable to the change of C source and N source in theenvironment;and could be grown and metabolized by nitrate and nitrite nitrogen.The comprehensive growth conditions,environmental adaptability and nitrogen removal performance were all better than those of the above three kinds of single strains,and were more suitable for bioaugmentation.(2)Sludge system bioaugmented by the compound bacteria could significantly improve the nitrogen removal efficiency of the high ammonia nitrogen wastewater,especially for the rate of the nitrogen removal.When HRT=48h,the maximum ammonia oxidation rate increased from 7.04 mg/L/h to 12.2 mg/L/h;and when changing the HRT to 24 h,the maximum ammonia oxidation rate could reach to 15.53 mg/L/h,Which was higher than the single heterotrophic nitrifying strain,and was equivalent to the ammonia oxidation rate of the autotrophic nitrifying bacteria.The addition of YM could effectively improve the resistant capability of the sludge system to the hydraulic retention time,and processing capacity of the sewage system.(3)The maximum total nitrogen removal rate of the reactor which bio-enhanced by YM immobilized sponge ball was 25.42 mg/L/h to 27.35 mg/L/h,and the rate of nitrogen removal was significantly better than the ways by polyethylene embedding(15.27 mg/L/h).(4)For low concentrations ammonia wastewater treatment,the hydraulic retention time was shortened from 48 h to 24 hours and 16 hours.The sludge system bio-enhanced by heterotrophic nitrifying compound bacteria YM was more stable than the non-enhanced sludge system,the rate of total nitrogen removal was faster,nitrite and nitrate nitrogen appeared earlier.It is proved that the main advantage of bioaugmentation by YM was significantly increased the nitrogen removal rate of the system.The bioaugmentation could shorten the HRT and increased the sewage treatment capacity under the condition of stable operation.(5)The YM did not become a dominant group in the bio-enhanced reactor after long-term operation,but the reactor still maintained high nitrogen removal efficiency.It is indicated that the bioaugmentation could accelerated the variation of the sludge system community,that is,to some extent,the nitrogen removal activity of local microorganism was stimulated,and the microbial population functional changes was promoted. |
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