Membrane fouling total suspended solids

Reverse osmosis can remove dissolved metals to very low levels. It can also remove a variety of pollutants such as cyanide and residual organics from refinery wastewater. However, because it is an expensive process, it would be competitive only if removal of total dissolved solids is also required. It also requires extensive pretreatment to prevent membrane fouling and deterioration [52]. The pretreatment processes may include filtration to remove suspended solids, pH adjustment, softening, and activated carbon treatment to remove organics and chlorine. A major drawback of the RO process is the handling and disposal of the reject stream, which can amount to 20-30% of the influent flow. 

UF and MF membranes alone do not remove total organic carbon (TOC) and tri-halomethane (THM) precursors [13]. Hence, pre-treatment entails addition of chemicals such as coagulants (FeCl3 or FeS04), alum or polyaluminium chloride to increase the size of suspended solids and colloidal particles and thus prevent or minimise colloidal, organic, and/or biological fouling. In the case of seawater desalination, membrane filtration has proven to be superior to multimedia filtration [14,15]. 

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