[Treatment Efficiency and Microbial Community Diversity in a Magnetic Field Enhanced Sequencing Batch Reactor (SBR)]

The application of SBR reactors is becoming more common and in order to further improve the efficiency of their treatment it has been proposed to add a magnetic field to SBR systems. The effects of different magnetic fields on the degradation efficiency of conventional pollutants in an SBR was studied. MiSeq high-throughput sequencing techniques were used to analyze the diversity of microbial communities in activated sludge under magnetic field conditions. These results show that the addition of a magnetic field improves the performance of a SBR system to an extent and magnetic induction effects are most obvious at 7×10^-2 T. This is identified through a significant effect on the removal efficiency of total nitrogen and an increase in the denitrification rate from 65.69% to 85.98%. It also significantly improves the activity of sludge dehydrogenase and has a positive effect on the removal of various pollutants. The diversity of microbial communities in activated sludge under different magnetic field intensities shows a greater microbial abundance and diversity in the active sludge. The bacterial domain in the experimental SBR includes 14 phyla, which are mainly Proteobacteria (25.3%-61.5%), Bacteroidetes (18.6%-46.2%), Actonobacteria (5.3%-47.2%), and Acidobacteria (0.4%-4.0%). Important denitrification bacteria such as Rhodoblastus, Paracoccus of α-Proteobacteria, Alicycliphilus, Comamonas, Xenophilus, Acidovorax, Dechloromonas, Thauera of β-Proteobacteria, Desulfovibrio of δ-Proteobacteria and Planctomycetes, etc. at a moderate magnetic induction of 7×10^-2 T have a high abundance and there is an internal relationship between this and an increase in denitrification efficiency. Polyphosphate-accumulating organisms (PAOs) such as Acinetobacter, Pseudomonas, Propionicimonas, etc., are present at higher levels under these conditions and follow the same trends as for the phosphorus removal rates. There is a correlation between bacterial community structure changes and sewage treatment efficiency in activated sludge. Applied magnetic fields have a positive effect on sewage treatment by changing the microbial community structure.