Synergistic control of membrane biofouling using linoleic acid and sodium hypochlorite.

Biofouling is a major operational problem in the reverse osmosis (RO) process, affecting the membrane performance. Although sodium hypochlorite (NaOCl) is used to chemically clean the biofouled membranes, high concentrations of NaOCl cause morphological and chemical damage to the RO membrane. The objective of this study is to enhance chemical cleaning efficiency by combining with a dispersion agent (linoleic acid, LA) that does not harm the RO membrane, to overcome the disadvantages of NaOCl. Biofilm cells were initially dispersed with LA treatment and biofouled layers were subsequently cleaned using NaOCl at low concentration. The optimized combination resulted in 3.9-4.4 times higher flux recovery efficiency than that with individual treatments. Furthermore, the combination decreased the volume and thickness of the biofilm as well as the amount of extracellular polymeric substances. Taken together, the combined treatment of LA and NaOCl significantly improves RO biofouling control.