Patent ID: 8236178

Claim:
A method for operating reverse osmosis membrane filter systems with membrane filters to recover water by using both the filtrate and brine retentate, comprising: a. injecting sulfur dioxide (SO 2 ) into water streams undergoing reverse osmosis filtration at an injection point before reverse osmosis membrane filters sufficient to scavenge and remove dissolved oxygen, serve as a biocide to prevent membrane fouling, reduce alkalinity scaling, and reduce iron deposit build-up on the reverse osmosis membrane filters at a concentration, which will not adversely affect membrane material, b. filtering the sulfur dioxide treated water through the reverse osmosis membrane filters to produce a filtrate and separated brine retentate containing less than 0.15% by weight of the salts of Na, Ca, Mg, Cl, SO 4 , or CO 3 or combinations thereof, c. adjusting the pH of the filtrate and discharging the same for reuse, d. monitoring the brine concentrations of the retentates for at least one of the following: i. Sodium Adsorption Ratio (SAR) ii. electrical conductivity (EC), ii. mono-valent cation adsorption ratio levels, and iv water pH to discharge the brine retentates before their brine concentrations are too saline for soil adjustment and raising plants, e. adding at least one of the following to adjust the pH and calcium ion concentration of the discharged brine retentates: i. acid, ii. soluble compounds releasing calcium ions on liquid dissolution, iii. acid and soluble compounds releasing calcium ions on liquid dissolution, and f. applying the pH and calcium ion adjusted discharged brine retentates to soils until soil and soil water concentrations of sodium absorption ratio (SAR) are less than 15, electrical conductivity (EC) less than 2 dS m −1 (m mho cm −1 ), cation exchange capacity (CEC) less than 57.5 centimoles/kg, and a pH less than 8; the specific soil ratios and concentration levels selected for raising a particular plant and reduce soil bicarbonates/carbonates to increase soil porosity and improve water penetration.