The feed was provided by a peristaltic pump (Watson Marlow 401U/D1) controlled by the level sensor inside the reactor. Sludge mixing was provided by a magnetic stirrer (Heidolph, Hei-Standard). The circulation of the mixed liquor along the mesh surface and the return of the retentate into the reactor were provided by a second peristaltic pump (Watson Marlow 505S) applying a cross flow velocity of about 10 m h1. A third peristaltic pump (Watson Marlow 401U/DM3) was installed to extract the effluent out of the system and to provide the necessary transmembrane pressure (TMP) for filtration. An airtight vessel of approximately 100 mL was installed down-flow from the third pump to assess
the presence of oversaturated biogas in the effluent. The effluent flowed out this vessel into a collection tank.