Biogas Production from Concentrated Municipal Sewage by Forward Osmosis, Micro and Ultrafiltration

Abstract

Direct application of anaerobic digestion to sewage treatment is normally only possible under tropical weather conditions. This is the result of its diluted nature and temperatures far from those suitable for anaerobic conversion of organic matter. Then, direct application of anaerobic treatment to sewage would require changing temperature, concentration, or both. Modification of sewage temperature would require much more energy than contained in the organic matter. Then, the feasible alternative seems to be the application of a pre-concentration step that may be accomplished by membrane filtration. This research studied the pre-concentration of municipal sewage as a potential strategy to enable the direct anaerobic conversion of organic matter. Three different membrane processes were tested: microfiltration, ultrafiltration and forward osmosis. The methane potential of the concentrates was determined. Results show that biogas production from the FO-concentrate was higher, most likely because of a higher rejection. However, salt increase due to rejection and reverse flux of ions from the draw solution may affect anaerobic digestion performance.

Direct membrane filtration (DMF) of municipal wastewater by mixed matrix membranes (MMMs) filled with graphene oxide (GO): Towards a circular sanitation model

“…Compared to commercial membranes used for wastewater treatment and organic matter concentration, these PES-GO membranes achieved similar or better COD removal. For instance, Gong et al [55] achieved 30.9-37.6 mg COD/L in permeate with a commercial PVDF-UF membrane, whereas Ortega-Bravo et al [56] achieved 49 mg COD/L in permeate with a commercial PES-UF membrane.…”