Integrated anaerobic fluidized-bed membrane bioreactor for domestic wastewater treatment

• An integrated anaerobic fluidized-bed membrane bioreactor was developed.
• Methane productivity decreased while more VFAs accumulated with a shorter HRT.
• The membrane fouling was more serious at a shorter HRT than longer HRT.
• GAC addition reduced protein content in cake layer and helped membrane filtration.

An integrated anaerobic fluidized-bed membrane bioreactor (IAFMBR) system with granular activated carbon (GAC) as carrier was developed to treat domestic wastewater with energy recovery. We investigated a laboratory-scale IAFMBR with chemical oxygen demand (COD) of about 300 mg/L at different hydraulic retention time (HRT). The removal of COD of 75.8%, 73.6% and 54.1% was achieved at respective HRT of 8, 6 and 4 h, resulting in respective methane yield was 140, 180 and 190 L CH4(STP)/kgCODremoved and conversion of 45.2%, 53.1% and 43.8% of COD into methane in biogas. The transmembrane pressure of membrane increased more rapidly at a shorter HRT than a longer HRT, suggesting that membrane fouling rate was accelerated at short HRTs. The amount of GAC added into the inner tube of IAFMBR controlled essentially the membrane fouling process. Supplementation of GAC reduced protein content in layer cake and helped membrane filtration.