THE NOVEL OSMOTIC MEMBRANE BIOREACTOR FOR WASTEWATER TREATMENT

A novel osmotic membrane bioreactor (OsMBR) for potable water reuse is presented. The system utilizes a submerged forward osmosis (FO) membrane module inside a bioreactor. Through osmosis, water is transported from the mixed liquor across a semi-permeable membrane, and into a draw solution (DS) having a higher osmotic pressure. To produce potable water, the diluted DS is treated in a reverse osmosis (RO) unit; the by-product is a reconcentrated DS for reuse in the FO process. Preliminary results from experiments conducted with a flat-sheet cellulose triacetate FO membrane demonstrated high sustainable flux and relatively low reverse transport of solutes from the DS into the mixed liquor. The FO membrane was found to reject 98% of organic carbon and 90% of ammonium-nitrogen; the OsMBR process (bioreactor and FO membrane) was found to remove greater than 99% of organic carbon and 97.7% of ammonium-nitrogen, respectively; suggesting a better compatibility of the OsMBR with downstream RO systems than conventional membrane bioreactors.