Study On Microbial Community Competition And Collaboration In Activated Sludge From Wastewater Treatment Plants In Cold Area

Activated sludge process is the most widely used biological treatment method in urban sewage treatment.The microorganisms in activated sludge remove pollutants through competition and cooperation.This article through to xinjiang region 5 oxidation ditch process sewage plants and laboratory run 3 SBR reactors activated sludge sampling,through high-throughput sequencing,the community structure of activated sludge,the paper analyzes the main bacteria causing sludge bulking,explore the bulking sludge and the expansion function of denitrification bacteria in the sludge,and the changing rule of the function of phosphorus accumulating bacteria.Combined with environmental factors,the competitive and cooperative relationship among filamentous bacteria,denitrifying bacteria and phosphorous accumulating bacteria was investigated.The main research results of this paper are as follows:(1)The 5 sewage treatment plants can basically meet their respective design effluent standards,among which 3 sewage treatment plants have filamentous sludge expansion in operation.A total of 41 phyla,888 bacteria genera,38 fungi phyla,122 fungi genera were found in the sewage plant.Actinobacteria significantly proliferated in the expanded sludge of sewage plants,and Ascomycota was the dominant fungal phylum in the expanded sludge of sewage plants,with a relative abundance of 56.60% ?72.68%.A total of 35 phyla,508 bacterial genera,22 fungal phyla and 72 fungal genera were detected in the reactor.Bacteroidetes were obviously proliferated in the activated sludge cultured by sodium acetate,and the Actinobacteria were enriched by glucose carbon source.Basidiomycota is the dominant fungal phylum of reactor expanded sludge,with a relative abundance of 48.80% ? 94.64%.(2)The filamentous fungi of Saprospiraceae?norank,Candidatus?Microthrix,Flavobacterium at low temperature has stronger competitiveness to the carbon source,Trichococcus has a strong ability to compete for granular organic matter,and Haliscomenobacter and Sphaerocritters have a high competitive ability for essential growth factors under the condition of unbalance of nitrogen and phosphorus.Thiothrix proliferation occurred in different reactors inoculated with sludge after culture with sodium acetate,and Thiothrix was highly competitive with sodium acetate carbon source.(3)AOB and NOB compete with filamentous bacteria for carbon source and dissolved oxygen,and AOB and NOB are less competitive than filamentous bacteria.SVI was negatively correlated with AOB and NOB,the correlation coefficients of SVI and AOB and NOB in sewage treatment plants were-0.451 and-0.403,respectively,and the correlation coefficients of SVI and AOB and NOB in the reactor were-0.537and-0.591,respectively.(4)In denitrifying bacteria,Thauera,Hyphomicrobium and Pseudomonas have obvious advantages in competing with filamentous bacteria in the difficult degradation of organic matter,Dechloromonas has certain advantages in the competition for sodium acetate carbon source,and Zoogloea has a strong ability in the utilization of glucose carbon source.(5)Candidatus?Accumulibacter and Acinetobacter were not dominant in competing with filamentous bacteria for carbon source and dissolved oxygen,while Tetrasphaera and other p-accumulating bacteria had certain advantages in competing with complex organisms.The competitiveness of polyphosphobacteria to sodium acetate was generally higher than that of glucose,among which Alcaligenes and Microlunatus were more competitive to glucose.