Patent ID: 8277660
Filing Date: 2012-10-02
Classification: B01D,C02F

Abstract:
1. A method of removing elements from feed water comprising the steps of a) receiving feed water containing silica and hardness ions and at a natural pH of about 8.1, b) treating the feed water with a weak-acid cation-exchange resin to reduce the hardness to less than 1 mg/L, followed by c) treating with a 1 micron cartridge filter to reduce the SDI to less than 1.0, d) further treating the treated feed water to a low-pressure reverse osmosis (RO) process at about 85% recovery, e) injecting about 3.5 mg/L of a silica-specific antiscalant into the low-pressure RO reject stream, f) treating the antiscalant-injected low pressure RO reject stream in a high-pressure RO system to obtain a final recovery of greater than 90%, with the final RO reject stream containing super-saturated silica at about 4 times the saturation level of silica in water.