| Sewage treatment plant not only bear a great deal of sewage processing tasks,but also relates to the natural ecological balance and environmental protection.The tail water produced by the urban sewage treatment plant contains a lot of microbialpathogenns,especially pathogenic bacteria.When discharged into the sea,it not only harms to the surrounding people,but also poses a threat to the ecological security of the sea.Many cases had reported that people were infected with pathogens coming from sewage wastewater treatmen plants and thus died in recent centuries.However,there are no laws or standards related to the amount of pathogens in outflows in our country.The microbial communityand community's changes with seasonsin the outfalls were investigated in thisstudy,so it's very important to use modern molecular biology technology to research tail water microbial community structure.The biological safety of tail water near the coast of the developing countries should be paid more attention.In this paper,this study to Qingdao Haibo river sewage treatment plant at all levels of process water as the research object.Quantitatively detected bacte-ria,fungi,fecal coliform and enterococcus faecaliswereat all levels of Sewage Treatment plant water by building plate counting;Using real-time quantitative polymerase chain reaction to analyze Escherichia coli,Enterococcus faecaliswere,Aeromonas of sewage treatment process;Using high-throughput sequencing technologies to analyze microbial community structure of Haibo river sewage treatment plant tail water in four seasons;This topic selects sewage treatment plant emissions tail water of Wheat Island and Haibo river sewage treatment plant in Qingdao as the research object,by using high-throughput sequencing technologies,researching in the process of tail water sea biological community structure and biomass,analyzing the tail water dynamic distribution rule in the process of pathogenic bacteria in the sea.The results were as below:(1)The result of plate count showed that the treatment effect of MSBR on the bacteria,fungi,Fecal coliform and Enterococcus faecaliswere is very obvious,the quality of effluent water meet the standard.Real-time PCR results has the same trend with plate count.But the content of bacteria in real-time PCR results was obviously higher than the corresponding bacteria content in the plate count method.The trend of same bacteria basically identical except a few sampling points.The content of bacteria has a big difference between different month,but the relationship with temperature is not absolute.(2)In total,28 phyla,76 classes were detected in treated wastewater.The mian phylum in four seasons were Proteobacteria,Bacteroidetes,Actinobacteria,Firmicutes and Planctomycetes.Proteobacteria accounted for 42.54%,48.3%,48.28%,42.9% in spring,summer,autumn,winter,and was the dominant phylum in four seasons.?-Proteobacteria was dominant on class level.There were 203 species in the treated wastewater whose relative abundance was more than 0.2%,including 18 pathogens,21 nitrogen and phosphorus removal bacteria and 11 pollutant degradation bacteria.(3)Among the 18 pathogens,season characteristics were obvious,for example,Arcobacter spp.were found in four seasons,while Legionella spp.were found only in summer.Mycoplasma spp.were found in summer,autumn and winter.While Mycobacterium mageritense was only found in spring.Thus we should take different measures to avoid being infected with season changing.The high-throughput sequencing result showed that the pathogenic genes are mainly related to cancers,immune system diseases,infectious diseases and metabolic diseases,and the total rate of disease genes were no more than 1%.(4)Microbial community structure of Sewage treatment plant tail water in the process of the sea showed a certain change,the species and the number of bacteria are decreased with the increase of the distance.It was found that bacteria were distributed in 20~28 phyla in three seasons.On level of phylum,the Proteobacteria occupies the absolute advantage,followed by the Bacteroidetes and Firmicutes.Among them,the proportion of Proteobacteria and Firmicutes in all the bacteria were in inverse proportion to the distance from the tail water diffusion,and Bacteroidetesis the opposite.In the Class level,Gammaproteobacteria,Betaproteobacteria,Epsilon proteobacteria with the diffusion distance increases,the number gradually decreased,but the number of Flavobacterium and Alphaproteobacteria was gradually increased.The species and quantity of the pathogenic bacteria in sea outfall are the most,but reduced to a large extent with the gradual decrease of the diffusion and migration of the tail water,and there was very little pathogenic bacteria after 500 m.But water dilution effect is not good in the three sampling points of Haibohe sewage treatment plant.The number of Aquibacter zeaxanthinifaciens increased in two saosons,and the types of pathogens has increased signs,this has a great relationship with the situation of the sea,and there are many factories near Jiaozhou Bay,so it will have a greater impact on the species and quantity of pathogenic bacteria. |
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