title: Characterization of the size-fractionated biomacromolecules: tracking their role and fate in a membrane bioreactor.
abstract: This article presents a study aimed at the fractionation and characterization of what is thought to be one of the most complex organic mixtures produced by activated sludge: biomacromolecules (BMM). Photometric quantification combined with excitation-emission matrix (EEM) fluorescence spectroscopy and nuclear magnetic resonance (NMR) measurements were used to characterize BMM in a membrane bioreactor (MBR) from a chemical perspective. Overall, the BMM in sludge supernatant were mainly present in three fractions: colloidal BMM (BMMc, >0.45 μm), biopolymeric BMM (BMMb, 0.45 μm-100 kDa) and low molecular weight (MW) fraction (<5 kDa). The analysis of fluorescence regional integration (FRI) showed that the organics in membrane permeate and those in the low-MW fraction of sludge supernatant were of similar chemical composition. The characterization by NMR suggested that the BMMc fraction had similar carbon content of proteins and polysaccharides. In contrast, the BMMb and the low-MW BMM were proved to be carbonaceous and aromatics, respectively. Moreover, because of the high MW and gelling property, polysaccharides were found to have a high potential to accumulate on the membranes. In addition, the lipids present in the BMMb of the sludge supernatant were demonstrated to be another important foulant due to their large size. Our results also indicated that aromatic proteins had a higher fouling propensity than tryptophan proteins though they were of similar size nature. This work could be useful for better understanding of the chemical nature of BMMs in MBRs.
authors.affiliation: School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, PR China. fgmeng80@126.com
authors.forename: Fangang
authors.initials: F
authors.lastname: Meng
authors.forename: Zhongbo
authors.initials: Z
authors.lastname: Zhou
authors.forename: Bing-Jie
authors.initials: BJ
authors.lastname: Ni
authors.forename: Xing
authors.initials: X
authors.lastname: Zheng
authors.forename: Guocheng
authors.initials: G
authors.lastname: Huang
authors.forename: Xiaoshan
authors.initials: X
authors.lastname: Jia
authors.forename: Shiyu
authors.initials: S
authors.lastname: Li
authors.forename: Ya
authors.initials: Y
authors.lastname: Xiong
authors.forename: Matthias
authors.initials: M
authors.lastname: Kraume
mesh_terms: D019149:Bioreactors; D009682:Magnetic Resonance Spectroscopy; D008970:Molecular Weight; D011134:Polysaccharides / Q000737:chemistry / Q000302:isolation & purification*; D011506:Proteins / Q000737:chemistry* / Q000302:isolation & purification; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*
chemical_list: D011134:Polysaccharides; D011506:Proteins; D012722:Sewage