Analysis of dynamic membrane build-up in an aerobic membrane bioreactor

• The particulate content is key to the correct dynamic membrane build-up. • The initial dynamic membrane build-up is not affected by the filtration flux. • Faster fouling compaction is induced by the increased filtration flux. • The fouling mechanism of the dynamic membrane is flux independent. • Air backflushing appears to be the best physical cleaning strategy. This study evaluates the dynamic membrane build-up of a nitrifying aerobic membrane bioreactor operated at high fluxes. The process achieved complete nitrification and a marked reduction in organic load. The build-up of the dynamic membrane was evaluated under different filtration fluxes (50–400 L/hm 2 ). The effect of particle content and different cleaning strategies were also assessed. Results show that filtration flux has no influence on the initial construction of the dynamic membrane or on effluent quality, which achieves acceptable turbidity levels for its reuse in less than four minutes. However, operation at high fluxes does lead to cake layer compaction in shorter operating times. Metabolite content is key to the formation of dynamic membranes, but without the presence of particles, the separation efficiency of the dynamic membrane is reduced. Results also indicate that air-backwashing is the best physical cleaning strategy among those tested, as it removes some of the pore-blocking material and enables longer filtration times between cleanings. In addition, the off-spec product time is less than one minute after each cleaning.