Thin film nanocomposite membrane for reduced organic fouling in forward osmosis process

Membrane fouling is a major problem affecting the efficiency of membranes in applications such as brackish water, seawater desalination, and water treatment.

A major limiting factor of forward osmosis (FO) membranes, particularly in pressure retarded osmosis (PRO) mode, is fouling by natural organic matter.

In this work an international team of researchers from Malaysia, Iran, Canada and the UK investigated the effect of a nanocomposite substrate on the fouling of a thin film nanocomposite (TFN) membrane due to organic foulants in PRO mode.

The TFN membrane was synthesised by coating a polyamide film over the surface of a substrate made of polysulfone–titanium dioxide.

The TFN membrane always showed much higher FO water flux than the typical thin film composite (TFC) membrane prepared from the pristine polysulfone substrate.

Reduced internal concentration polarisation (ICP) following a significant decrease in the structural parameter in the nanocomposite substrate causes the mass transfer coefficient of the substrate to increase.

In PRO mode, bovine serum albumin (BSA) removal in the presence of Ca2+ confirmed that the TFN FO membrane could significantly mitigate fouling tendency compared to a typical TFC membrane.

The results also show that fouling in TFN FO is highly reversible, recovering >92% permeate flux after a simple water rinse process.

A complete study of the membrane fouling is reported, with detailed scientific discussion. This is believed to be the first report on the effect of the nanocomposite membrane on membrane fouling in PRO mode.

Desalination, Volume 348, 1 September 2014, Pages 82–88.