Submerged membrane adsorption bioreactor as a pretreatment in seawater desalination for biofouling control

Submerged membrane adsorption bioreactor (SMABR) was investigated as a pretreatment to reverse osmosis (RO). SMABR removed organic matter by adsorption and biological degradation. At a powder activated carbon (PAC) residence time of 66 d (1.5% of PAC replacement daily), higher organic removal was achieved with removal of a majority of biopolymers (94–97%) and humics (71–76%). A continuous MBR operation with the optimal PAC residence time of 66 d was conducted and compared with MBR with no PAC replenishment in terms of the removal of organic and microbes. High removal of organics of up to 72% was maintained with only a marginal increment of trans-membrane pressure and stable bioactivity (total cell number and adenosine tri-phosphate) during the 50 d of operation. The SMABR was found to be a sustainable biological pretreatment to RO with only a small amount of PAC requirement (2.14 g of PAC/m3 of seawater treated).

► Submerged membrane adsorption bioreactor (SMABR) as a pretreatment to reverse osmosis (RO).
► Optimization of powder activated carbon (PAC) retention time in terms of organic removal and biomass.
► A small amount of PAC was sufficient (2.13 g/m3) to reduce biofouling potential in SMABR.
► Stable long term operation (50 d) of SMABR with a residence time of PAC of 66 d.
► Low biofouling potential after SMABR treatment in terms of assimilable organic carbon (AOC) concentration.