Effects of Microbial Degradation of Biofoulants on Microfiltration Membrane Performance in a Membrane Bioreactor

• Published in: Environmental science & technology Vol. 44; no. 22; pp. 8644 - 8648
• Main Authors: Okamura, Daisuke, Mori, Yoshihiko, Hashimoto, Tomotaka, Hori, Katsutoshi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 15.11.2010
• Subjects: Acids; Applied sciences; Ascomycota - growth & development; Ascomycota - isolation & purification; Ascomycota - metabolism; Biodegradation; Biodegradation, Environmental; Biofouling - prevention & control; Bioreactors - microbiology; Exact sciences and technology; Fungi; Membrane filters; Membranes; Pectins - metabolism; Pollution; Reactors; Remediation and Control Technologies; Ultrafiltration; Uronic Acids - metabolism; Waste Disposal, Fluid; Water treatment; Biodegradation; Activated sludge; Fouling; Filtration; Pollutant behavior; Reaction product; Permeation; Biological purification; Fungi; Membrane separation; Microfiltration; Membrane reactor; Bioreactor; Biofouling; Fungi Imperfecti; Waste water purification; Performance; Acid medium
• ISSN: 0013-936X; 1520-5851
• DOI: 10.1021/es102321m

In membrane bioreactors (MBRs) for wastewater treatment, membrane fouling, particularly biofouling caused by soluble microbial products (SMP), is a nuisance problem causing decreases in permeation flux. In a previous study, we identified primary biofoulants of microfiltration (MF) membranes in SMP as polysaccharides containing uronic acids that undergo inter- and intramolecular ionic cross-linking by polyvalent cations, forming a gelatinous mass that clogs membrane pores. In the present study, we therefore attempted to isolate biofoulant-degrading microorganisms from activated sludge on a polygalacturonic acid-overlaid agar medium and evaluate their efficiency for preventing biofouling of MF membranes. Among the isolates, the fungal strain HO1 identified as Phialemonium curvatum degraded 30% of polysaccharides containing uronic acids into smaller molecules in a SMP solution containing a high concentration of saccharides after 30 days of cultivation. Microfiltration tests using a laboratory-scale submerged MBR indicated that the filtration resistance of this degraded SMP solution was lower than that of the control SMP solution without fungal inoculation. Importantly, accumulation of gelatinous mass on the membrane responsible for biofouling was avoided in the SMP solution augmented with P. curvatum HO1 during the microfiltration test. This is the first report to describe a new method for avoiding biofouling of MBRs by microbial degradation of primary biofoulants.