Effects Of Typical Industrial Pollutants On The Performance Of Nitrogen Removal And The Community Structure Of Aerobic Denitrifying Bacteria

The infrastructure construction of supporting facilities in China's industrial wastewater treatment industry lags behind the production of industrial wastewater,which causes some industrial wastewater to be directly discharged into the urban sewage pipe network,which has a negative impact on the biological nitrogen removal system of the sewage treatment plant.In recent years,some studies on the effects of some typical pollutants in industrial wastewater such as phenol,heavy metals and salinity on anaerobic denitrification have made great progress,but the impact on new biological nitrogen removal technology-aerobic denitrification Relatively small.Taking the enriched and screened aerobic denitrifying bacteria group as the research object,the mechanism of the influence of typical pollutants in industrial wastewater?including NaCl,Cr?VI?and TC?on aerobic denitrifying bacteria was studied.The main results of this study are as follows:?1?The method of intermittent aeration maintaining high dissolved oxygen can effectively enrich the aerobic denitrifying bacteria group.Under aerobic conditions,the inoculated sludge does not have the ability to remove nitrate nitrogen,and the enriched flora can be quickly removed.High concentration of nitrate nitrogen,the removal rate is as high as 11.67 mg·?L·h?^-1.During the enrichment process,the extracellular polymer content remained low and increased,and the microbial diversity decreased significantly.The dominant genus in the community was changed from obligate anaerobic Simplicispira to obligate aerobic Pseudomonas,while the napA gene abundance is increased by orders of magnitude.The growth of the Pseudomonas sp.and napA gene abundance is the main reason why the enriched flora has good aerobic denitrification.?2?NaCl,Cr???and TC can inhibit aerobic denitrification performance of denitrifying bacteria,denitrifying rate from 2.31 mg·?g·h?^-1 down to 0.44,1.43,and0.52 mg·?g·h?^-1,respectively.Gradient concentration of NaCl,Cr?VI?and TC can gradually improve the tolerance of aerobic denitrifying bacteria to these typical pollutants,and achieve rapid growth in a wide range of NaCl,Cr?VI?and TC wastewater.With the removal of nitrate nitrogen,the denitrification rate increased to7.95,4.53 and 6.49 mg·?g·h?^-1,respectively.?3?The aerobic denitrifying bacteria group will increase the yield of extracellular polymer,especially the extracellular protein content,by 8.8 to 12.9 times under the long-term stress of typical pollutants.In addition,the stress of typical pollutants will have a slight impact on N₂O emissions.The stress of NaCl causes more N₂O in the aerobic denitrification process,while the stress of TC can reduce the N₂O emission in the process,but the amount of this emission reduction has a very small effect compared with the air background value.?4?Typical pollutants can significantly affect the aerobic denitrifying flora community diversity and population structure,and the types of pollutants are different,and the impact results are also different.Long-term stress of Cr?VI?and TC can reduce the community diversity of aerobic denitrifying bacteria and reduce the abundance of napA gene.The stress of NaCl and Cr?VI?causes Azoarcus to replace Pseudomonas and Thauera as the dominant species in aerobic denitrifying bacteria.TC does not affect the dominant position of Pseudomonas and Thauera,but increased Pseudomonas and decreased the relative abundance of Thauera in the community.