Polyaniline-coated conductive media promotes direct interspecies electrons transfer (DIET) and kinetics enhancement of low-strength wastewater treatment in anaerobic fluidized bed membrane bioreactor (AFMBR)

Polyaniline (PANI) was applied as coating materials to develop conductive surface on polyethylene terephthalate (PET) bead and polyvinylidene fluoride (PVDF) pellet termed as C-PET and C-PVDF as fluidized media in anaerobic fluidized bed membrane bioreactor (AFMBR). Parallel operation with AFMBRs showed that the fouling rate was lower for the C-PET and C-PVDF media than uncoated ones to scour membrane, and this was more pronounced as the organic loading rate was higher. Methane production rate was about 50% faster for the C-PET and C-PVDF media, and their use in the AFMBR system promoted methane yield by 14 to 190% higher than uncoated ones. 16S rRNA gene analysis revealed predictable results for methanogenic archaeal community structure (high abundance in Methanothrix), in line with the reactor performance observed, and suggestive of known Direct Interspecies Electron Transfer (DIET) metabolism. The bacterial analysis revealed common syntrophic species typically seen in anaerobic reactors, however, few known DIET species were also found, suggesting that more works are needed to elucidate pathways and syntrophies which may be activated by the PANI coating. Our results supported that conductive polymeric fluidized media should have great potential to promote kinetic enhancement in AFMBR treating low-strength wastewater.