Effects Of Magnetic Field On Microbial Community Of Simulated SBR Treatment System

The application of SBR reactors is becoming more common,and in order to further improve the efficiency of its treatment,it was proposed to add a magnetic field to the SBR reaction system to improve its operating performance.The effects of different magnetic field on the degradation efficiency of conventional pollutants in the reaction system were studied.MiSeq high-throughput sequencing technique was used to analyze the diversity of microbial communities in activated sludge under magnetic field conditions,and macrogeome sequencing technology was used to analyze the microbial community and functional changes of activated sludge.The main findings are as follows:(1)The addition of magnetic field improved the performance of SBR system to a certain extent.and 700 GS magnetic field strength effect was most obvious.Among them,the applied magnetic field had a significant effect on the removal efficiency of total nitrogen in SBR reaction system,and the denitrification rate increased from 65.69% to 85.98% at 700 GS.The addition of magnetic field significantly improved the activity of sludge dehydrogenase,and thus also had a positive effect on the removal of various pollutants.The diversity of microbial community of activated sludge under different magnetic field intensity shows that the microbial abundance and diversity of active sludge are the highest at 700 GS magnetic field.(2)The bacterial domains in the experimental SBR reactor were identified to be14 phyla,mainly Proteobacteria(25.3%-61.5%),Bacteroidetes(18.6%-46.2 %),Actoba cteria(5.3%-47.2%),Acidobacteria(0.4%-4.0%).Important denitrification bacteria such as Rhodoblastus?Paracoccus of ?-Proteobacteria,Alicycliphilus?Comamonas?Xenophilus?Acidovorax ? Dechloromonas ? Thauera of ?-Proteobacteria,Desulfovibrio of?-Proteobacteria and Planctomycetes,etc.at moderate magnetic field strength,especially700 GS,had the highest abundance,and there is an internal relationship with the increase of denitrification efficiency.Typical PAOs such as Acinetobacter,Pseudomonas,Propionicimonas,etc.,had higher levels under moderate magnetic field conditions and had the same trends as phosphorus removal rates.There is a certain correlation between bacterial community structure change and sewage treatment efficiency in activated sludge.The content of pollutant degrading bacteria in activated sludge was positively correlated with the removalrate of pollutants,and the applied magnetic field affected the wastewater treatment effect by changing the microbial community structure.(3)Select the most significant active diversity of 700 GS magnetic field under the conditions of the activated sludge and the control group of activated sludge for the macro genome sequencing.A total of 68 species,1773 genera and 3523 species were detected.Among them,most belong to the bacterial domain(95.93% ~ 95.88%).The content of nuclei is 0.089% ~ 0.154%,the eukaryotic domain is 3.2155% ~ 3.3800%,and the virus content is0.0158% ~ 0.0169%.In the 700 GS magnetic field,the growth of Microgenomates,Fusobacteria,Parcubacteria,Tenericutes,Chlamydiae,Chrysiogenetes,Cyanobacteria,Planctomycete,Chordata,Microsporidia,Phaeophyceae,Glomeromycota,Blastocladiomycota,Euryarchaeota and so on in the macrogeome of the activated sludge can be effectively promoted Some categories produce inhibitory effects.The results showed that the 700 GS magnetic field could effectively promote the activity of Thioalkalivibrio,Azoarcus,Thaueratao,Cellulomonas,Dermacoccus,Luteipulveratus,Arsenicicoccus,Kocuria,Mycobacterium,Propionibacterium and Propionibacterium in the activated sludge.,Streptomyces,Candidatus Saccharimonas and other dominant growth.In contrast,the 700 GS magnetic field,to a certain extent,inhibit the growth of some dominant bacteria in activated sludge.(4)700GS magnetic field action Activated sludge did not change the ranking of major KEGG functional genes in the macro genome.The results showed that the contents of KEGG-related genes in the two genomes of the activated sludge were as follows:Carbohydrate metabolism,Amino acid metabolism,Energy metabolism,Signal transduction change.(5)The denitrification rate of the SBR reaction system is closely related to the functional genes involved in nitrogen metabolism in the active sludge macro genome.The 700 GS magnetic field can effectively promote the growth of related genes in the denitrification process,thus improving the removal rate of nitrogen in the wastewater treatment.Through the analysis of the functional genes related to nitrogen metabolism in the macro-genome of activated sludge and its metabolic pathway,it was found that denitrification-related functional genes dominate.The contents of the heavy genome of the activated sludge in the 700 GS magnetic field were higher than those in the non-magnetic field,and the mineralization of ammonia monooxygenase,hydroxylamine dehydrogenase,nitric oxide,reductase,nitrous oxide,As well as nitrite reductas,ferredoxin-nitrite reductase,ferredoxin-nitrate reductase,and hydroxylamine reductase related genes involved in the ammoniation reaction were inhibited to different degrees in the 700 GS magnetic field.The amount of hydrazine synthase,hydrazine dehydrogenase was higher than that of the untreated magnetic field,And the content of the mold powder in the process of performing anaerobic ammonium oxidation was 1.8 times that of the unmanned magnetic field at 700 GS,which indicated that the 700 GS magnetic field could effectively promote the growth of the mold.