RESUMEN
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 248â¯days. The system demonstrated 56% volatile solids degradation at an organic loading rate of 0.40â¯g-VS/(L·d) in 15â¯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 12â¯kPa without membrane cleaning during the experimental period due to low filtration flux (0.01-0.07â¯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.