Long-term effects of salinity on extracellular polymeric substances, microbial activity and microbial community from biofilm and suspended sludge in an anoxic-aerobic sequencing batch biofilm reactor

• Biofilm had higher SAOR, SNOR, and SNRR than S-sludge at 0–8% salinity.• The raise of PN and PS in EPS was the cell protective responses to high salt stress.• The sum of PN and PS in EPS from biofilm was higher than those from S-sludge.• The microbial community in biofilm and S-sludge changed as the increase of salinity.