Study On Degradation Characteristics And Denitrification Performance Of Activated Sludge Under Pulse Aeration

In view of shortcomings of low denitrification efficiency in wastewater treatment process,a new method of pulse aeration was put forward to strength denitrification.Controlling the aeration on/off alternately which fed with synthetic wastewater,a favorable aerobic/anoxic environment has been constructed,to meet the nitrification while denitrification can be achieved smoothly.The main research contents and results were as follows:(1)The process parameters of pulse aeration was investigated through denitrification,effluent stability and energy saving,5/10min erobic/anoxic was selected as the final ideal operating cycle.Through analysis and comparison experiments,keeping influent COD volume loading in 0.45KgCOD/m3·d,SRT 20d,and influent sludge concentration 2000mg/L will have the highest denitrification efficiency and best treatment effect.(2)According to the optimum parameters above,comparing the effect of pulse aeration(5/10min)with continuous aeration under the same conditions.There was not obvious difference in removal of organic matter,TOC and COD removal efficiency all above 80%;Pulse aeration has certain advantages in terms of denitrification,TN removal rate reached more than 60%;The decolorization and denitrification effects of pulse aeration on dyeing wastewater were investigated.The results showed that the pulse aeration achieved good results in terms of the removal of organic matter and nitrogen,moreover,the decolorization rate reached more than 80%.(3)The Influence of pulse aeration on active sludge extracellular polymeric substances(EPS)and effluent soluble microbial products(SMP)were investigated,The results showed that compared with continuous aeration,EPS and SMP decreased in pulse aeration mode,moreover,there was a positive correlation between them.The content of EPS increased with the SRT prolonged under pulse aeration conditions,while the SMP was opposite;The LB-EPS in EPS has a significant influence on sludge sedimentation,positively correlated with SVI values,while TB-EPS has little effect.(4)The denitrifying bacteria under pulsed and continuous aeration were detected by Miseq sequencing technology.The results showed that both aeration systems have higher microbial diversity,pulse aeration slightly more rich;OTU cluster analysis indicated that the diversity of denitrifying bacteria was similar in the end domestication of the two aeration ways,but also has a certain gap;classification level on the phylum,have similar denitrifying bacteria structure,phylum Proteobacteria was dominance;In case of genus levels,the common dominant species of both aeration were Betaproteobacteria_unclassified spp,Proteobacteria_unclassified spp and Bacteria unclassified spp;The specie composition of pulse aeration was relatively stable in late period analyzed from species genus,indicating that pulse aeration has more stable denitrification system.