The study was performed by using a bench-scale ADMBR equipped with an external cross-flow filtration unit (Fig. 1).
The reactor had a total volume of 898 mL (W H D: 9.5 10.5 9 cm) and a working volume of 684 mL. The level of the mixed liquor was kept constant by using a level sensor connected to the influent pump. The filtration support had an inner volume of 60 mL (W H D: 20 1.5 2 cm). A monofilament woven mesh made of polyamide/nylon (SaatiMil PA 7, Saati s.p.a., Italy) with openings of 200 lm, thread diameter of 120 lm, mesh count of 31/cm and 39% opening area (data from the supplier) was inserted into the central longitudinal part of a filtration support. The filtration area was 40 cm2 (L W: 20 2 cm). The overall working volume composed by reactor, membrane support and pipe connections, was 745 mL.