Fouling Reverse osmosis technology

J.V. Lepore and R.C. Ahlert, Fouling in Membrane Processes, in Reverse Osmosis Technology, B.S. Parekh (ed.), Marcel Dekker, New York, pp. 141-184 (1988). 

Hyperfiltration (Reverse Osmosis) is a form of membrane distillation or desalination (desalting) operating with membrane pore sizes of perhaps 1 to 10 Angstrom units. The various individual RO component technologies have improved tremendously over the last 20 to 25 years, and resistance to fouling and permeate output rates have benefited. Nevertheless, all RO plants remain susceptible to the risk of fouling, and adequate pretreatment and operation is essential to minimize this problem. 

Micro-ultrafiltration and reverse osmosis are mature technologies for separations based on molecular exclusion and solution-diffusion mechanisms, respectively. Cleaning and maintenance procedures able to control fouling to an acceptable extent have made these processes commercially suitable. 

Tang, C.Y., Criddle, Q.S., Eu, C.S., and Leckie, J.O. 2007. Effect of flux (transmembrane pressure) and membranes properties on fouling and rejection of reverse osmosis and nanofiltration membranes treating perfluorooctane sulfonate containing waste water. Environmental Science and Technology, 41 2008-14. 

Ridgway H.F., Kelly A., Justice C., and Olson B.H., Microbial fouling of reverse osmosis membranes used in advanced wastewater treatment technology Chemical bacteriological and ultrastiuctural analyses. Applied and Environmental Microbiology 46 1983 1066-1084. 

L. Y. Dudley, Membrane autopsies for reversing fouling in reverse osmosis. Membrane Technology 95, 9-12 (1998). 

Boerlage S.F.E., Kennedy M.D., Bonne P.A.C., Galjaard G., Schippers J.C. (1997), Modified fouling index for the prediction of the rate of flux decline in reverse osmosis, nano- and ultrafiltration systems, Proc. AWWA Membrane Technology Conference, New Orleans, Feb. 97, 979-999. 

Zhu X., Elimelech M. (1997), Colloidal fouling of reverse osmosis membranes measurements and fouling mechanisms. Environmental Science and Technology, 31, 3654-3662. 

Electrodialysis (ED) is used to remove ionized substance from hquids through selective ion-permeable membranes. ED is the most widely commercialized electromembrane technology. Desalination of brackish water is the area of electrodialysis application with the largest number of installations. This chemical-free technology competes with reverse osmosis. Electrodialysis shows better resistance to fouling and scaling. It also has an economical advantage in desalination of low-salinity solutions [13]. Also, it should be kept in mind that because of small material consumption ED is the most environmental friendly process for solution desalination [14]. 

Currently, the pressure-driven membrane processes, reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and microfiltration (MF), are widely used in water treatment, biotechnology, food industry, medicine, and other fields (Baker 2004). However, one of the main problems arising from the operation of the manbrane units is membrane fouling, which seriously hampers the applications of manbrane technologies (Scot and Hughes 1996). 

S.Y. Kwak, S.H. Kim, and S.S. Kim, Hybrid organic/inorganic reverse osmosis (RO) membrane for bactericidal anti-fouling. 1. Preparation and characterization of TiOj nanoparticle self-assembled aromatic polyamide thin-film-composite (TFC) membrane. Environmental Science Technology 35 (2001) 2388-2394. 

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