Characterization of Cake Layer in Submerged Membrane Bioreactor

• Published in: Environmental science & technology 2007-06, Vol.41 (11), p.4065-4070
• Main Authors: Meng, Fangang, Zhang, Hanmin, Yang, Fenglin, Liu, Lifen
• Format: Article
• Language: English
• Subjects: Applied sciences; Bacteria - cytology; Bacteria - growth & development; Biological and medical sciences; Biological treatment of waters; Biopolymers; Bioreactors; Biotechnology; Cluster analysis; Environment and pollution; Exact sciences and technology; Filtration; Fourier transforms; Fundamental and applied biological sciences. Psychology; General purification processes; Industrial applications and implications. Economical aspects; Membrane reactors; Membranes, Artificial; Microscopy, Confocal; Microscopy, Electron, Scanning; Particle physics; Particle Size; Pollution; Scanning electron microscopy; Sewage - analysis; Sewage - chemistry; Spectrometry, X-Ray Emission; Spectroscopy, Fourier Transform Infrared; Studies; Wastewaters; Water Purification; Water treatment; Water treatment and pollution
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es062208b

Cake layer formation on the membrane surface has been a major challenge in the operation of membrane bioreactors (MBRs). In this study, the cake layer formation mechanism in an MBR used for synthetic wastewater treatment was investigated. The major components of cake layer were systematically examined by particle size analyzer (PSA), scanning electron microscopy (SEM), confocal laser scanning microscopy (CLSM), X-ray fluorescence (XRF), energy-diffusive X-ray analyzer (EDX), and Fourier transform infrared (FTIR) spectroscopy. The results indicate that the small particles in sludge suspension had a strong deposit tendency on the membrane surface. The SEM and CLSM analysis exhibited that bacterial clusters and polysaccharides were significant contributors to membrane fouling. The main components of biopolymers were identified as proteins and polysaccharide materials by the FTIR. The examination by EDX and XRF demonstrated that Mg, Al, Ca, Si, and Fe were the major inorganic elements in fouling cake. Furthermore, the results suggest that bridging between deposited biopolymers and inorganic compounds could enhance the compactness of fouling layer. During the operation of MBRs, the biopolymers and inorganic elements in the bioreactor should be controlled to minimize membrane fouling.