REJECT RECOVERY REVERSE OSMOSIS (R2RO)
A process for the recovery of purified water from a reverse osmosis reject stream includes preconditioning a reject stream to remove scaling ions and provide preconditioned water; separating any precipitate that forms in the preconditioned water to form a feed stream; subjecting the feed stream to high pressure membrane filtration system including a recirculating, high pressure pump generating a permeate stream and a second reject stream; adding a make-up water stream to the feed stream; and separating the permeate stream as purified water. Additional features and embodiments are also provided.
1 . A process for achieving high salt concentration and/or high permeate recovery from a reject stream from a first reverse osmosis process including a first reverse osmosis permeate stream and first reverse osmosis reject stream, comprising:
preconditioning the first reverse osmosis reject stream to remove scaling ions and provide preconditioned water;
separating any precipitate that forms in the preconditioned water to form a feed stream;
subjecting the feed stream to high pressure reverse osmosis membrane filtration system including a recirculating, high pressure pump generating a second permeate stream and a second reject stream;
adding a make-up water stream to the feed stream; and
separating the second permeate stream as purified water.
2 . The process of claim 1 , further comprising removing at least one member of the group consisting of colloidal impurities and inorganic complexes from the reject stream following the preconditioning step.
3 . The process of claim 2 , wherein said removing step is accomplished by treating the reject stream by at least one of ultrafiltration and microfiltration.
4 . The process of claim 1 , wherein the high pressure membrane filtration is at a pressure between 100 and 150 barg.
5 . The process of claim 1 , wherein the high pressure membrane filtration is at a pressure of more than 140 barg.
6 . The process of claim 1 , wherein the high pressure membrane filtration is conducted in a disk membrane system.
7 . The process of claim 1 , wherein the high pressure membrane filtration is conducted in a plate and frame membrane system.
8 . The process of claim 1 , further comprising heating the feed stream.
9 . The process of claim 1 , further comprising adding an anti-sealant to the feed stream.
10 . The process of claim 1 , further comprising cleaning the membrane filtration system by a low pressure permeate flush.
11 . The process of claim 1 , wherein the second reject stream has a salt concentration up to 12%-15%.
12 . The process of claim 1 , wherein the high pressure membrane filtration system operates between 2000-2100 psi.
13 . The process of claim 1 , wherein the reject stream has a total dissolved solids content of between 120000-150000 mg/l.
14 . The process of claim 1 , wherein total water recovery from an RO system including permeate from the first reverse osmosis and permeate from the second reverse osmosis is at least 98% when it is not limited by TDS.
15 . A combined reverse osmosis process for achieving high salt concentration and/or high permeate recovery from an upstream first reverse osmosis process and a downstream second reverse osmosis process, said first reverse osmosis process including a first reverse osmosis permeate stream and a first reverse osmosis reject stream and said downstream second reverse osmosis process including a second reverse osmosis process permeate stream and a second reverse osmosis reject stream, comprising:
treating cooling tower blowdown in a first reverse osmosis process to produce a first reverse osmosis process permeate stream and a first reverse osmosis process reject stream;
preconditioning the first reverse osmosis reject stream to remove scaling ions and provide preconditioned water;
separating any precipitate that forms in the preconditioned water to form a feed stream;
subjecting the feed stream to the second reverse osmosis process including a recirculating, high pressure pump generating a second reverse osmosis process permeate stream and a second reverse osmosis process reject stream;
adding a make-up water stream to the feed stream; and
separating the second reverse osmosis process permeate stream as treated water.
16 . A combined reverse osmosis process for achieving high salt concentration and/or high permeate recovery from an upstream first reverse osmosis process and a downstream second reverse osmosis process, said first reverse osmosis process including a first reverse osmosis permeate stream and a first reverse osmosis reject stream and said downstream second reverse osmosis process including a second reverse osmosis process permeate stream and a second reverse osmosis reject stream, comprising:
treating recycled and reused refinery water in a first reverse osmosis process to produce a first reverse osmosis process permeate stream and a first reverse osmosis process reject stream;
preconditioning the first reverse osmosis reject stream to remove scaling ions and provide preconditioned water;
separating any precipitate that forms in the preconditioned water to form a feed stream;
subjecting the feed stream to the second reverse osmosis process including a recirculating, high pressure pump generating a second reverse osmosis process permeate stream and a second reverse osmosis process reject stream;
adding a make-up water stream to the feed stream; and
separating the second reverse osmosis process permeate stream as treated water.
17 . A combined reverse osmosis process for achieving high salt concentration and/or high permeate recovery from an upstream first reverse osmosis process and a downstream second reverse osmosis process, said first reverse osmosis process including a first reverse osmosis permeate stream and a first reverse osmosis reject stream and said downstream second reverse osmosis process including a second reverse osmosis process permeate stream and a second reverse osmosis reject stream, comprising:
treating recycled and reused coal to chemical production water in a first reverse osmosis process to produce a first reverse osmosis process permeate stream and a first reverse osmosis process reject stream;
preconditioning the first reverse osmosis reject stream to remove scaling ions and provide preconditioned water;
separating any precipitate that forms in the preconditioned water to form a feed stream;
subjecting the feed stream to the second reverse osmosis process including a recirculating, high pressure pump generating a second reverse osmosis process permeate stream and a second reverse osmosis process reject stream;
adding a make-up water stream to the feed stream; and
separating the second reverse osmosis process permeate stream as treated water.
18 . A combined reverse osmosis process for achieving high salt concentration and/or high permeate recovery from an upstream first reverse osmosis process and a downstream second reverse osmosis process, said first reverse osmosis process including a first reverse osmosis permeate stream and a first reverse osmosis reject stream and said downstream second reverse osmosis process including a second reverse osmosis process permeate stream and a second reverse osmosis reject stream, comprising:
treating flue gas desulfurization water in a first reverse osmosis process to produce a first reverse osmosis process permeate stream and a first reverse osmosis process reject stream;
preconditioning the first reverse osmosis reject stream to remove scaling ions and provide preconditioned water;
separating any precipitate that forms in the preconditioned water to form a feed stream;
subjecting the feed stream to the second reverse osmosis process including a recirculating, high pressure pump generating a second reverse osmosis process permeate stream and a second reverse osmosis process reject stream;
adding a make-up water stream to the feed stream; and
separating the second reverse osmosis process permeate stream as treated water.
19 . The process of claim 1 , comprising sending said second reject stream to a crystallizer without a brine concentration step.
20 . The process of claim 1 , wherein an internal flow distribution system with the membrane filtration system ensures minimal laminar flow space and therefore minimal fouling.
21 . The process of claim 19 , wherein removal of a brine concentration step decreases operating and capital costs.
22 . An apparatus for practicing the process of claim 1 .
23 . The process of claim 1 , wherein the second reject stream has a salt concentration up to 15%.
24 . The process of claim 1 , wherein total water recovery from an RO system including permeate from the first reverse osmosis and permeate from the second reverse osmosis is up to 99%.