Comparison between moving bed-membrane bioreactor (MB-MBR) and membrane bioreactor (MBR) systems: Influence of wastewater salinity variation

Two pilot plant systems were investigated for the treatment of wastewater subject to a gradual increaseof salinity. In particular, a membrane bioreactor (MBR) and a moving bed biofilm membrane bioreactor(MB-MBR) were analyzed. Carbon and ammonium removal, kinetic constants and membranes foulingrates have been assessed. Both plants showed very high efficiency in terms of carbon and ammoniumremoval and the gradual salinity increase led to a good acclimation of the biomass, as confirmed bythe respirometric tests. Significant biofilm detachments from carriers were experienced, which contributedto increase the irreversible superficial cake deposition. However, this aspect prevented the porefouling tendency in the membrane module of MB-MBR system. On the contrary, the MBR pilot, evenshowing a lower irreversible cake deposition, was characterized by a higher pore fouling tendency.