The results demonstrated that an anaerobic DM can be achieved on a mesh with large pore size (200 lm) treating municipal wastewater at ambient temperature. The large pore size allows for high membrane fluxes (15–20 L m2 h1) applying low TMP (lower than 50–100 mbar). The treatment system achieved an average COD removal of
higher than 80% for HRTs higher than 0.5 d. On the contrary at HRTs lower than 0.5 d the average COD removal decreased to 50–60%. The results also demonstrated that the biofilm composing the cake layer of the DM significantly concurs in obtaining the high treatment efficiency. COD mass balance suggested that the low HRTs applied to the
ADMBR produced dissolved methane concentrations higher than those that are estimated by Henry’s law, thus causing important methane loss through the reactor effluent.