Patent ID: 8101083

Claim:
A pre-treatment method for reverse osmosis filtration systems with membrane filters for filtering waters with suspended solids in a liquid fraction for improved maintenance comprising: a. injecting sulfur dioxide (SO 2 ) into the waters at an injection point before the reverse osmosis membrane filters at a concentration level, which will not adversely affect the reverse osmosis membrane filter performance, but sufficient to self agglomerate the suspended solids, scavenge and remove dissolved oxygen, act as a biocide, prevent membrane fouling from alkalinity scaling, iron deposit build-up, and acid leach heavy metals from the suspended solids into the liquid fraction, b. filtering the sulfur dioxide treated waters through the reverse osmosis membrane filters to produce a metal free permeate and metal enriched separated brine retentate, c. adjusting the pH of the permeate for reuse, and d. periodically blowing down the brine retentate to reduce osmotic pressure buildup in the reverse osmosis filtration system, e. raising the pH of the blown down brine retentate with an alkaline source to a level to precipitate heavy metals as metal hydroxides, and f. removing the metal hydroxides from the brine retentate to form a metal free brine retentate.