Impacts of sulfadiazine on the performance and membrane fouling of a hybrid moving bed biofilm reactor-membrane bioreactor system at different C/N ratios

The performance and membrane fouling of a hybrid moving bed biofilm reactor-membrane bioreactor (MBBRMBR) system was evaluated when exposed to 0.5 mg/L of antibiotic sulfadiazine (SDZ). Results indicated that although SDZ reduced the removal efficiency of NH4+-N and TN (up to 12%) and TOC (up to 6%) at low C/N (2.5 and 4), it had no significant effect at high C/N (6 and 9). It was found that SDZ was removed 75% and 58% at high C/N of 9 and low C/N of 2.5, respectively. SDZ decreased the ratio of volatile biomass/total biomass and sludge particle size and increased the concentrations of extracellular polymeric substance (EPS) and soluble microbial product (SMP) in MBR. Consequently, this accelerated the membrane fouling rates, with an average increase of 6.85 kPa/d at low C/N (2.5) and 0.513-0.701 kPa/d at medium and high C/N (4, 6 and 9).