Study On Key Enzymes In PAO,GAO And Their Subgroups For Denitrification And Phosphorus Removal

At present,one of the water environment pollution problems urgently needed to be solved in China is the eutrophication of water bodies,and the widely used and cost-effective enhanced biological phosphorus removal process(EBPR)is one of the research hotspots in practical engineering.At present,many scholars have studied the influencing factors of the competition between Phosphorus Accumulating Organisms(PAOs)and glycogen accumulating organisms(GAOs)in the EBPR system from a macro perspective,but studying the competition of enzyme activities against the two from a micro perspective Induction is rare,ignoring the fundamental factor that microorganisms implement and regulate the related functions of biochemical reactions is the enzyme.Therefore,in this project,by studying the type of carbon source,C/P,C/N,temperature and p H value,polyphosphate hydrolase(exopolyphosphatase,PPX),acid phosphatase and alkaline phosphatase in the competition between polyphosphate bacteria and polysaccharide bacteria The impact of the three key enzyme activities,and the use of metagenomics high-throughput sequencing technology to study the impact of five influencing factors on microbial community diversity and bacterial structure,in order to explore the key enzymes on the competition mechanism of phosphorus accumulating bacteria and glycan bacteria Induction and regulation effects,batch experiments are carried out by adjusting the influencing factors to optimize the system's biological nitrogen and phosphorus removal efficiency,and provide references for the actual operating parameters of the EBPR process.In this project,a Sequencing Batch Reactor Activated Sludge Process(SBR)reactor was used,and the sludge of a sewage treatment plant in Changchun City was used as the inoculation sludge.The artificial domestic water distribution was used to simulate the urban domestic sewage.Oxygen alternate mode of operation,successfully enriched polyphosphate bacteria and glycan bacteria and their subgroups.The results show that PPX enzyme activity is higher in the anaerobic stage than in the aerobic stage,and acid and alkaline phosphatase activities are higher in the aerobic stage than in the anaerobic stage.Adjusting the three carbon sources of acetic acid,propionic acid and glucose,it was found that under the condition of acetic acid carbon source,PPX enzyme,acid and alkaline phosphohydrolase activity is higher,and PAOs are the dominant strains and the relative abundance ratio is relatively large.Adjusting the carbon-phosphorus ratio has no significant effect on the acid phosphatase activity.The alkaline phosphatase activity increases with the increase of the carbon-phosphorus ratio.The PPX enzyme activity is greatest when the carbon-phosphorus ratio is 133.33,and the carbon-phosphorus ratio is 100 The smallest,when the carbon-to-phosphorus ratio is 100,the dominant species PAOs account for the highest relative abundance ratio.Adjust the carbon-to-nitrogen ratio,PPX enzyme activity increases with the increase of carbon-to-nitrogen ratio,has no significant effect on acid and alkaline phosphatase activities,and the system's nitrogen and phosphorus removal rate bacteria is above 90%,PAOs are at five carbons Under the condition of nitrogen ratio,they are all dominant bacteria,and their relative abundance ratio is similar.The results of adjusting the reactor temperature show that 20 ?-25 ? is the optimal temperature for PAOs and PPX enzymes,and 20 ? is the optimal temperature for acid and alkaline phosphatase;the temperature is between 25?-35?,the temperature increases,The denitrification and dephosphorization efficiency of the system becomes worse,and the relative abundance ratio of phosphorus-accumulating bacteria decreases.The results of adjusting the p H value of the reactor indicate that the appropriate p H value of PAOs is 6.0-7.0,and the appropriate p H value of PPX enzyme is 6.5-7.5.The p H value increases and decreases,and the predicted changes in the relative abundance of functional genes of the flora are consistent with the enzyme activity.