Foam Fractionation-Flotation as Partial Pretreatment for Reverse Osmosis

摘要

Foam flotation equipment was designed, constructed, and tested to assess its utility as a partial pretreatment method on San Francisco Bay water prior to its desalination by reverse osmosis (RO). Test data obtained from a dual-flow facility revealed that foam flotation is effective in reducing feed turbidity, usually by a factor of five (ranging from 3-fold to 10-fold) in terms of national turbidity units. However, due to the poorly-matched single pair of RO units employed, the results could not detect whether feed clarity improvement significantly affected the flux decline or quality of the desalted water produced by RO. The dual-flow facility was comprised of two pretreatment and RO trains and was used for simultaneous comparative testing of conventional cartridge filtration and for the further foam flotation clarification, followed by RO applied to both pretreated feed streams. Surface tension, membrane plugging, and water conductivity were also monitored. The results of this study indicate that further evaluation using well-matched pairs of RO ion-exchange membranes is justified.