High efficiency reverse osmosis pretreatment

Reverse osmosis requires good pretreatment to prevent membrane fouling and loss of performance. Because it is seldom better than 60 to 70% efficient, there is a relatively high cost for pumping and discharging the additional supply water consumed. Nevertheless, it is good as a bulk water roughing process for purification. 

In nuclear industry ultrafiltration was applied in the pretreatment stage before reverse osmosis that needs removal of potential foulants from feed streams. Very often ultrafiltration is combined with precipitation or complexation. Small ions bound by macromolecular chelating agent form complexes, which are retained by UF membrane. Such an enhanced ultrafiltration becomes an efficient separation process with high decontamination factors, sometimes compared with those... 

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