Anaerobic dynamic membrane bioreactor for wastewater treatment at ambient temperature

• Anaerobic dynamic membranes can be developed at ambient temperature.
• Dynamic membrane over large pore size mesh can obtain efficient solid rejections.
• Biofilm forming the dynamic membrane significantly contributed to organics removal.
• Methane oversaturation occurred due to ambient temperature and low HRTs.

A bench-scale dynamic membrane (DM) bioreactor was operated to evaluate the anaerobic treatment of a synthetic municipal wastewater at ambient temperature. The DM was developed over a large pore size (200 μm) mesh in order to improve sludge filterability and reduce energy consumption. The system achieved average organic removals higher than 80% and 90% for total COD and filtered COD, respectively. Results also demonstrated that the biofilm, which the DM is made of, played a significant part in obtaining the overall organic removal efficiency. The large pore size of the mesh allowed for high membrane fluxes (approximately 15–20 L m−2 h−1) applying low TMP (usually lower than 50–100 mbar). Fluxes higher than 20 L m−2 h−1 produced low solid removal efficiency indicating deterioration of the DM. COD mass balance suggests that the low hydraulic retention times applied to the system caused methane loss through the effluent due to oversaturation.