Influence of COD:N ratio on sludge properties and their role in membrane fouling of a submerged membrane bioreactor. (1st February 2016)

• Record Type: Journal Article
• Authors: Hao, L.; Liss, S.N.; Liao, B.Q.
• Is Part Of: Water research. Volume 89(2016)
• Page Start: 132
• Page End: 141
• Publication Date: 2016-02-01
• Subjects: COD:N -- Membrane bioreactor -- Membrane fouling -- Industrial wastewater -- Extracellular polymeric substances -- Sludge properties; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.11.052
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: The effect of COD:N ratio on sludge properties and their role in membrane fouling were examined using a well-controlled aerobic membrane bioreactor receiving a synthetic high strength wastewater containing glucose. Membrane performance was improved with an increase in the COD/N ratio (100:5–100:1.8) (i.e. reduced N dosage). Surface analysis of sludge by X-ray photoelectron spectroscopy (XPS) indicates significant differences in surface concentrations of elements C, O and N that were observed under different COD/N ratios, implying changes in the composition of extracellular polymeric substances (EPS). Fourier transform-infrared spectroscopy (FTIR) revealed a unique characteristic peak (CO bonds) at 1735 cm −1 under nitrogen limitation conditions. Total EPS decreased with an increase in COD/N ratio, corresponding to a decrease in the proteins (PN) to carbohydrates (CH) ratio in EPS. There were no significant differences in the total soluble microbial products (SMPs) but the ratio of PN/CH in SMPs decreased with an increase in COD/N ratios. The results suggest that EPS and SMP composition and the presence of a small quantity of filamentous microorganisms played an important role in controlling membrane fouling. Graphical abstract: Highlights: An increase in COD:N ratio led to improved membrane performance. Surface concentrations of elements O and N and C bonds are different under different COD:N ratios. Bound EPS/SMP composition is more important than the quantity in controlling membrane fouling. The presence of a small quantity of filamentous microorganisms led to improved membrane performance. A characteristic peak of FTIR at 1735 cm −1 was observed for sludge under N deficiency.