Study On Migration And Transformation Of Phenol In A~2/O Process

As a major coal resource province in China,coal coking industry has become a key industry in Shanxi Province,which has brought economic benefits to shanxi but caused serious environmental pollution.As an important measure to control environmental pollution,Coking wastewater treatment has drawn much attention from researchers.The research focuses mainly on the degradation of various pollutants in coking wastewater and the disposal or utilization of sludge,while lack of research on gaseous pollutants emitted from the coking wastewater.In recent years,the haze situation in China has been severe,which is closely related to the sewage treatment industry.Combined with the actual of coking wastewater treatment,the representative phenol in the coking wastewater was selected as the pollutant,and the A~2/O process was used as the carrier.Firstly,quantitatively analyze the amount of phenol volatilization during the reaction process.Through response surface analysis,study the interaction of various influencing factors,in order to provide data support and theoretical basis for making measures to control phenol volatilization and enable water plants tooperate at high efficiency and energy conservation;Secondly,through determining the carbon of the three stages of anaerobic,anoxic and aerobic processes in the A~2/O process,the carbon balance in the reaction process was analyzed to obtain the distribution law of the carbon source in gas,liquid and solid phases.Finally,the composition of microbial communities in different reaction stages was analyzed by high-throughput sequencing,and the dominant bacteria in different oxygen-containing environments were analyzed to provide the basis for isolation and culture of dominant bacteria in different environments.The main conclusions are as follows:1.In the process of treating coking wastewater with phenol as the main pollutant in the A~2/O process,under the condition of certain pollutant concentration,the main factors influencing the phenol volatilization during the reaction process include:aeration,temperature and hydraulic retention time.Response surface analysis shows that the order of influence on the volatilization of phenol is:phenol concentration>aeration>temperature>hydraulic retention time.When the temperature and aeration are at a high level,the volatilization of phenol is relatively high,so the influence of aeration and temperature should be considered first in controlling the volatilization of phenol.When the quality of the effluent meets the standard,try to select low aeration and low temperature operation,which also meets the requirements of environmental protection and energy conservation.2.In the total carbon of the A~2/O process system,64.9%of the carbon is transferred to solid phase used by microorganisms,in which aerobic stage plays a major role;8.9%of the carbon is discharged into the environment with the effluent;19.8%of the carbon is transferred to the atmosphere.Among the 6.5%total carbon entering the gas phase during the anaerobic reaction,5.9%is inorganic carbon and 0.6%is organic carbon;in the anoxic reaction,2.3%of the total carbon entering the gas phase,2.0%is inorganic carbon,and 0.3%is organic carbon;in the aerobic reaction,10.9%of the total carbon entering the gas phase,7.7%is inorganic carbon,and 3.2%is organic carbon.3.Using high-throughput sequencing to analyze the microbial community at each stage of the reaction,the proportions of Proteobacteria,Firmicutes,Bacteroidetes and Actinobacteria in the reaction stages are as high as 90.0%,91.4%,90.0%,and 91.1%respectively.During the transition from anaerobic environment to aerobic environment,the dominant bacteria changed obviously,the proportion of Proteobacteria in the reaction increased gradually from 10.0%to 63.6%.The proportions of Firmicutes and Actinobacteria are gradually reduce from 46.1%and 16.6%to 16.6%and 0.4%respectively.At the genera level,the main functional bacteria in the anaerobic stage include Lactococcus,Olsenella and Anaerofilum;the main functional bacteria in the anoxic stage include Lactococcus,Rhizobium,and Desulfovibrio;and the functional bacteria in the aerobic stage mainly include Rhizobium,Desulfovibrio,and Comamonas.