The Study On The Performance And Mechanism Of The Process Of Partial Nitrification And Anammox Enhanced By Low Frequency Electromagnetic Field

The phenomenon that organisms produce a weak magnetic field during physiological activities,so that organisms also have weak magnetism is called the biomagnetic effect.In recent years,this phenomenon has attracted more and more scholars' attention,and has been introduced into the field of environmental wastewater treatment.A certain intensity of electromagnetic field can stimulate the increase in the number and activity of bacteria.Partial nitrification,as a new type of nitrogen removal process,can be used as a pretreatment for anaerobic ammonia oxidation process.The combination of the two has a broad application prospect in biological nitrogen removal.However,due to the slow start of partial nitrification process,poor stability,long period of anaerobic ammonia oxidizing bacteria,harsh environmental requirements,and the generation of nitrate is not conducive to subsequent treatment and other shortcomings have always restricted the development and promotion of this new processThis study aimed at partial nitrification and anaerobic ammonia oxidation processes and existing problems,using biomagnetic effects,using low-frequency electromagnetic wave(EMW)irradiation strategy to strengthen the partial nitrification and anaerobic ammonia oxidation process startup process,to achieve improved nitrogen removal performance and rapid enrichment Based on the advantages of the corresponding functional flora and the promotion of the stable operation of the reactor,the microbial community structure changes and gene function prediction changes during the electromagnetic wave irradiation process were analyzed to reveal the electromagnetic wave irradiation enhancement mechanism.The main research conclusions are as follows:(1)Under the irradiation of 0.06 ?T intensity low-frequency EMW,it can obviously promote the start of partial nitrification process,saving 30%of the start time.When the intensity of low-frequency EMW exceeds 0.06 ?T,it will inhibit partial nitrification activity(2)In the face of the impact of high ammonia nitrogen load in the influent,the nitrogen removal performance of the reactor irradiated by low-frequency EMW showed better stability,and the nitrite accumulation rate was significantly improved,reaching more than 96%.On the 60th day of the reactor operation,the AOB specific oxygen consumption rate of the experimental group R2 exposed to 0.06 ?T intensity EMW was 0.728 mg(02)/g(MLSS).min,which was 51.9%higher than R1.(3)High-throughput sequencing results indicated that the relative abundance of Nitrosomonas increased from 2.0%of R1 to 5.5%of R2.Functional genes were predicted through the KEGG database,and the expression of functional genes involved in signal transduction,cell motility,and membrane transport in reactor R2 is high.In addition,the functional gene abundance predicted based on the COG database shows that the reactor R2 contains a higher content of ammonia monooxygenase than R1.Metagenome sequencing showed that based on the NR database,starting from the amino acid sequence of non-redundant proteins,through Fisher's exact test,and the two-tailed test of the confidence interval,the comparison of the abundance differences between the two samples R1 and R2,Nitrosomonas was the dominant bacterial group,and the abundance in the reactor R2 was significantly higher than that of R1(P<0.01)Based on the CAZy database,glycoside hydrolase,carbohydrate esterase,polysaccharide lyase,and carbohydrate binding modules are significantly improved in the reactor R2 under corresponding electromagnetic wave irradiation.From the genetic level,it was found that the biosynthesis of secondary metabolites can be stimulated under the irradiation of low-frequency EMW.(4)Anammox batch test results showed that the application of low frequency EMW with an intensity of 0.09 ?T can significantly shorten the start-up time of the mature granular sludge anammox process.Activity increased by 32.44%.The EMW of 0.20 and 0.25 ?T inhibited the activity of anammox bacteria.(5)Used a low-frequency EMW of 0.09 ?T intensity to irradiate the long-running UASB reactor can significantly shorten the start-up time of anammox process Compared with R1,the nitrogen removal performance of reactor R2 was greatly improved,especially the total nitrogen removal rate reached more than 88.87%.which was consistent with the theoretical optimal value.After the 11th day of reactor operation,the denitrification rates of the two reactors reached 2370.73 mg-N/m3/d and 2733.21 mg-N/m3/d,respectively.The nitrogen removal performance of R2 was improved by 15.3%compared to R1.Throughout the experiment,the ammonia nitrogen removal rate and nitrous nitrogen removal rate of reactor R2 were always higher than the control group(6)On day 120,high-throughput sequencing results showed that the application of low-frequency EMW with intensity of 0.09 ?T can increase the relative abundance of the main anammox bacteria.In particular,the proportion of Candidatus Brocadia in reactor R2 is 21.3%,while the proportion in reactor R1 is 7.8%.