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

Abstract

The long-term effects of salinity on extracellular polymeric substances (EPS), microbial activity and microbial community from biofilm and suspended sludge (S-sludge) in an anoxic-aerobic sequencing batch biofilm reactor (SBBR) were investigated. The increase of influent salinity from 0% to 8% caused the decrease of specific ammonium oxidation rate (SAOR), specific nitrite oxidation rate (SNOR) and specific nitrate reduction rate (SNRR) in biofilm from 3.89, 4.60 and 52mg N/(g MLSS h) to 1.01, 0.83 and 18mg N/(g MLSS h), respectively, and the decrease of SAOR, SNOR and SNRR in S-sludge from 3.57, 3.95 and 29mg N/(g MLSS h) to 0.71, 0.61 and 9mg N/(g MLSS h), respectively. As the salinity increased from 0% to 8%, the protein (PN) content in EPS from biofilm and S-sludge increased from 8.35 and 8.77mg/g VSS to 90.88 and 58.63mg/g VSS, respectively, and the polysaccharide (PS) content in EPS from biofilm and S-sludge increased from 3.05 and 4.03mg/g VSS to 57.55 and 62.63mg/g VSS, respectively. Nitratireductor lucknowense, Micropruina glycogenica, and Thiobacillus thioparus could grow more favorably in biofilm than in S-sludge at 0–8% salinity.