Patent ID: 8679347
Filing Date: 2014-03-25
Classification: B01D,B01J,C02F

Abstract:
1. A Multi-use Membrane Process, wherein flow streams are directed by automatically opening and closing shut-off valves in such a manner and with such a timed sequence of operations as to provide a reverse osmosis (RO) process followed by ion exchange (IX) of RO concentrate (RO-IX C ) with simultaneous regeneration of exhausted IX water softening resin using the RO concentrate, comprising: a) providing a multi-use membrane system comprising: b) operating in an ion exchange regeneration mode (IX c) pretreating said hardness-free influent using pretreatment methods selected from the group consisting of filtration, pH adjustment and addition of anti-scalant to produce pretreated hardness-free influent with Silt Density Index SDI d) pressurizing and introducing said pretreated hardness-free influent into said RO membrane system to purify said pretreated hardness-free influent and produce a membrane permeate product water and a membrane concentrate; e) recovering said membrane permeate product water at a rate in the range 80%-95% of a rate of said influent; f) removing said membrane concentrate from said RO membrane system at a rate in the range 5%-20% of the rate of said influent; g) diverting a fraction of said membrane concentrate having a total dissolved solids concentration (TDS) >5,000 mg/L into said IX regenerant solution holding tank; h) switching to a high recovery mode (RO-IX i) pretreating said blended influent water using pretreatment methods selected from the group consisting of filtration, pH adjustment and addition of anti-scalant to produce pretreated blended influent water with Silt Density Index SDI j) pressurizing and introducing said pretreated blended influent water into said RO membrane system to purify said pretreated blended influent water and produce said membrane permeate product water and said membrane concentrate; k) recovering said membrane permeate product water at a rate in the range 90%-99% of the rate of said influent; l) removing said membrane concentrate from said RO membrane system at a rate in the range of 25%- 60% of the rate of said influent; m) recycling said membrane concentrate directly under said membrane concentrate's own pressure or via said membrane concentrate holding tank and at least one of the pumps to one of said dual IX water softening resin columns at a rate in a range 25%-60% of the rate of said influent, with said dual IX water softening resin columns alternating in operation by switching from the exhausted IX water softening resin column to the fresh stand-by IX resin column to produce said hardness-free recycled RO concentrate; n) recovering said hardness-free recycled RO concentrate from said fresh stand-by IX resin column, blending said hardness-free recycled RO concentrate with said influent to produce said blended influent water, and repeating steps (i) through (m); o) regenerating said exhausted IX water softening resin column by simultaneously pressurizing and transferring said membrane concentrate from said IX regenerant solution holding tank, and producing said fresh stand-by IX resin column and a volume of spent IX regenerant waste; p) combining a process reject stream from said membrane concentrate, at a rate in the range 1%-10% of the rate of said influent with said spent IX regenerant waste to produce a combined effluent; q) removing and disposing of said combined effluent via sewer systems, wastewater treatment plants or via volume reduction type evaporators and crystallizers at a rate in the range 1%-10% of the rate of said influent; and r) repeating steps (b) through (q) by switching from said ion exchange regeneration mode (IX