Effect of magnetic fields on simultaneous nitrification and denitrification microbial systems

New progress in the deep understanding of the biocake layer property: Combined effect of neglected protein secondary structure, morphology, and mechanism

The application of magnetic fields (MFs) and magnetic particles (MPs) in water treatment has attracted widespread attention due to their stability, strong biological compatibility, and less chemical consumption. This study introduced MPs and MFs to GDM and probed their effects on filtration performance. Predeposited large MPs (P-large) and batch-added little MPs (B-little) intervened biocake layer development, forming more open and porous structures, they also reduced biomass secretion, resulting in flux increases of 13 % in P-large and 40 % in B-little than P-little, respectively. Besides, MFs controlled MPs distribution on the biocake layer, resulting in forming of more rough and open structures. A relatively lower magnetic field of 20 mT facilitated biomass secretion, while a higher magnetic field of 50 mT decreased biomass. Furthermore, applying magnetic fields decreased the ratios of α-helix and β-sheet, and increased random coil percentage. Thus, applying magnetic field mediation would contribute to the flux improvements in I-20 and I-50 by 29 % and 32 % relative to I-0. Economic analysis suggested introducing MPs and MFs to GDM was economically feasible, synergy of MPs and MFs had more economic advantages on the community scale and MPs-assisted GDM had significant economic advantages on both community and household scales. Future works should focus on developing new technologies for the recycling of MPs and membranes. This study provided new insight into the protein secondary structures associated with GDM performance and would encourage new sustainable MFs and MPs-assisted GDM technological developments.