Polyelectrolyte-modified polyethersulfone ultrafiltration membranes for wastewater treatment applications

This work reports on the use of the layer-by-layer (LbL) technique to modify the surface of polyethersulfone hollow fi bre (HF) ultrafi ltration membranes for wastewater treatment. The polyelectrolytes employed are poly (ethylenimine), poly (diallyldimethylammonium chloride) and poly (styrene sulfonate) to obtain up to three layers. Sludge supernatant was used as feed for fi ltrations and the throughput across the polyelectrolyte-modifi ed membrane was characterized by permeability measurement and the composition of the discharged permeates. Furthermore, the molecular weight cut off (MWCO) of the modifi ed membranes was determined. To evaluate real separation performance of polyelectrolyte-modifi ed membranes the total organic carbon (TOC) removal and the change in ultraviolet absorbance (UVA254) at 254nm as a function of the number of deposited layers were determined for the sludge supernatant. Between 30% and 50% TOC rejection was observed for modifi ed membranes as compared to only 15% for virgin membranes.