Revealing the effects of static magnetic field on the anoxic/oxic sequencing batch reactor from the perspective of electron transport and microbial community shifts.

ABSTRACT

The effects of static magnetic field (SMF) on an anoxic/oxic sequencing batch reactor were investigated from the perspective of electron transport via determining the variations of reduced/oxidized nicotinamide adenine dinucleotide (NADH/NAD+) ratio, NADH concentration, electron transport system activity (ETSA), poly-ß-hydroxybutyrate (PHB), extracellular polymeric substances (EPS), as well as the gene expression under different conditions. Moreover, the shifts of microbial community were also analyzed. The application of SMF with an appropriate intensity significantly improved the performance of the process, the abundance of the anoxic denitrifiers, and the activity of the aerobic denitrifiers. The NADH content, as well as ETSA were also enhanced, therefore, the total nitrogen removal efficiency of the process was increased. However, the overhigh SMF intensity resulted in the change of microbial community, meanwhile, had negative effects on the metabolism of microorganisms. Selecting a proper intensity is crucial for the SMF-enhanced biological wastewater treatment process.