Fouling of various kinds continues to plague membrane-based desalination and water treatment. An innovative, emerging approach to fouling control is the use of an osmotic driving force to reverse the flow through the membranes.  The removal efficiency of alginate as a model organic foulant has been experimentally assessed in a seawater matrix, for commercial seawater RO membranes, using cleaning protocols comprised of osmotic backwashing, physical and chemical cleaning. The effects of draw solution concentration and chemistry have been investigated. Results indicate that flux restoration achieved when osmotic backwashing was induced is significantly higher than for physical cleaning and comparable with that of the employed chemical cleaning protocol. Hence, it offers the potential for chemical free, membrane friendly and environmentally friendly cleaning of seawater RO membranes.  Numerical simulations further illustrate the process characteristics, which are intrinsically controlled by the concentration field, and offer a facile approach for optimization of osmotic cleaning.

Osmotic backwashing of organic-fouled reverse osmosis membranes: Efficiency and implications for fouling control

243rd National Meeting (2012)

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