Digestion performance and contributions of organic and inorganic fouling in an anaerobic membrane bioreactor treating waste activated sludge

• Published in: Bioresource technology 2019-01, Vol.272, p.63-69
• Main Authors: Hafuka, Akira, Mashiko, Riho, Odashima, Ryuto, Yamamura, Hiroshi, Satoh, Hisashi, Watanabe, Yoshimasa
• Format: Article
• Language: English
• Subjects: Anaerobic digestion; Anaerobiosis; Biofuels; Biogas; Bioreactors; Cross-flow filtration; Filtration; Membrane fouling; Methane - metabolism; Polytetrafluoroethylene membrane; Sewage; Waste Disposal, Fluid
• ISSN: 0960-8524; 1873-2976
• DOI: 10.1016/j.biortech.2018.09.147

[Display omitted] •An anaerobic membrane bioreactor was applied for the digestion of waste activated sludge.•A VS degradation ratio of 56% and a biogas methane content of 76% were obtained.•TMP remained under 12 kPa during 248-day operation without membrane cleaning.•Inorganic fouling accounted for 16% of physically irreversible fouling.•Organic fouling accounted for 45% of physically irreversible fouling. This study evaluates the performance of an anaerobic membrane bioreactor (AnMBR) digesting waste activated sludge. A digestion reactor equipped with an external hollow fiber microfiltration membrane module was operated in continuous-mode for 248 days. The system demonstrated 56% volatile solids degradation at an organic loading rate of 0.40 g-VS/(L·d) in 15 days of hydraulic retention time. The average methane content in the biogas produced was 76% which is considerably high compared to that from a typical continuously stirred tank reactor. The transmembrane pressure remained under 12 kPa without membrane cleaning during the experimental period due to low filtration flux (0.01–0.07 m/d) and cross-flow-mode filtration. Ex situ membrane cleaning revealed that physically irreversible fouling was the dominant form of membrane fouling. Inorganic and organic fouling accounted for 16% and 45% of total membrane fouling, respectively.