Simultaneous nitrification-denitrification and membrane fouling alleviation in a submerged biofilm membrane bioreactor with coupling of sponge and biodegradable PBS carrier

Simultaneous nitrification-denitrification (SND) was achieved in submerged biofilm membrane bioreactor (SBF-MBR) treating low carbon/nitrogen (C/N) ratio wastewater. A novel bio-carrier coupling of sponge and biodegradable poly(butanediol succinate) (PBS) was applied as external carbon source and biofilm carrier. Result represented that NH4+-N and total nitrogen removal efficiencies were high of 99.1% and 94.3% in the SBF-MBR. Protein (PN) contents from SND-biofilm were reduced by 10.5% and 44.3% in TB-EPS and LB-EPS, while polysaccharides (PS) were reduced by 45.8% and 34.8%, respectively. 3D-EEM spectra indicated that protein-like, humic acid-like and fulvic acid-like substances were the main components in EPS and their peak intensities were reduced. Additionally, membrane fouling of SBF-MBR was improved after the achievement of biofilm. Microbial community analysis showed that Simplicispira, Thauera, Desulfovibrio, Dechlorobacter and Acinetobacter were dominant genus, which indicated co-existence of nitrifying bacteria, heterotrophic denitrifiers and aerobic denitrifiers in the SBF-MBR.