Publications (3)9.73 Total impact
Article: Characterization of organic membrane foulants in a submerged membrane bioreactor with pre-ozonation using three-dimensional excitation-emission matrix fluorescence spectroscopy.[show abstract] [hide abstract]
ABSTRACT: This study focuses on organic membrane foulants in a submerged membrane bioreactor (MBR) process with pre-ozonation compared to an individual MBR using three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy. While the influent was continuously ozonated at a normal dosage, preferable organic matter removal was achieved in subsequent MBR, and trans-membrane pressure increased at a much lower rate than that of the individual MBR. EEM fluorescence spectroscopy was employed to characterize the dissolved organic matter (DOM) samples, extracellular polymeric substance (EPS) samples and membrane foulants. Four main peaks could be identified from the EEM fluorescence spectra of the DOM samples in both MBRs. Two peaks were associated with the protein-like fluorophores, and the other ones were related to the humic-like fluorophores. The results indicated that pre-ozonation decreased fluorescence intensities of all peaks in the EEM spectra of influent DOM especially for protein-like substances and caused red shifts of all fluorescence peaks to different extents. The peak intensities of the protein-like substances represented by Peak T(1) and T(2) in EPS spectra were obviously decreased as a result of pre-ozonation. Both external and internal fouling could be effectively mitigated by the pre-ozonation. The most primary component of external foulants was humic acid-like substance (Peak C) in the MBR with pre-ozonation and protein-like substance (Peak T(1)) in the individual MBR, respectively. The content decrease of protein-like substances and structural change of humic-like substances were observed in external foulants from EEM fluorescence spectra due to pre-ozonation. However, it could be seen that ozonation resulted in significant reduction of intensities but little location shift of all peaks in EEM fluorescence spectra of internal foulants.Water Research 02/2011; 45(5):2111-21. · 4.86 Impact Factor
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ABSTRACT: In this paper, a novel submerged ultrafiltration (UF) membrane coagulation bioreactor (MCBR) process was evaluated for drinking water treatment at a hydraulic retention time (HRT) as short as 0.5h. The MCBR performed well not only in the elimination of particulates and microorganisms, but also in almost complete nitrification and phosphate removal. As compared to membrane bioreactor (MBR), MCBR achieved much higher removal efficiencies of organic matter in terms of total organic carbon (TOC), permanganate index (COD(Mn)), dissolved organic carbon (DOC) and UV absorbance at 254nm (UV(254)), as well as corresponding trihalomethanes formation potential (THMFP) and haloacetic acids formation potential (HAAFP), due to polyaluminium chloride (PACl) coagulation in the bioreactor. However, the reduction of biodegradable dissolved organic carbon (BDOC) and assimilable organic carbon (AOC) by MCBR was only 8.2% and 10.1% higher than that by MBR, indicating that biodegradable organic matter (BOM) was mainly removed through biodegradation. On the other hand, the trans-membrane pressure (TMP) of MCBR developed much lower than that of MBR, which implies that coagulation in the bioreactor could mitigate membrane fouling. It was also identified that the removal of organic matter was accomplished through the combination of three unit effects: rejection by UF, biodegradation by microorganism and coagulation by PACl. During filtration operation, a fouling layer was formed on the membranes surface of both MCBR and MBR, which functioned as a second membrane for further separating organic matter.Water Research 09/2008; 42(14):3910-20. · 4.86 Impact Factor
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ABSTRACT: The mini-pilot experiments of submerged membrane bioreactor (sMBR) for the drinking water treatment from a slightly polluted surface water supply was conducted for more than 110 days, with a hydraulic retention time of 0.5 h. Perfect ammonia removal (by 89.4%) were achieved by the sMBR through the biological nitrification. However, the capacity of the sMBR for organic matter removal was demonstrated to be low. The average removal efficiencies for TOC, CODMn, DOC, UV254, and corresponding THMFP and HAAFP were 28.6%, 33.5%, 21.5%, 15.1%, 34.1% and 24.7%, respectively, though much higher removal of 51.7% and 54.9% were obtained for BDOC and AOC, respectively. A sludge layer was observed on the UF membrane surface in the sMBR. The sludge layer could provide additional filtration for dissolved organic matter (DOM) in the mixed liquor, especially for organic molecules in the range of 5000–500 Da. Fractionation of DOM indicated that the sludge layer together with the UF membrane had the ability to reject hydrophobic neutrals, hydrophobic acids, and weakly hydrophobic acids by 45.0%, 42.7% and 48.1%, respectively; whereas hydrophobic bases and hydrophilic organic matter were separated mainly by the UF membrane, with the efficiencies of 11.3% and 14.6%, respectively.Chemical Engineering Journal.