Multifunctional method for membrane protection and biofouling control

Patent metadata

Field	Value
Publication number	US-2016185630-A1
Application number	US-201414586989-A
Country	US
Kind code	A1
Filing date	Dec 31, 2014
Priority date	Dec 31, 2014
Publication date	Jun 30, 2016
Grant date	—

Abstract

The invention provides methods and compositions for the protection of a membrane from both biofouling and from damage caused by a biocide. The invention utilizes PAA as both a biocide and as a reducing agent for other oxidizing biocides. This is especially beneficial because without the invention one would be forced to choose between preventing membrane biofouling or preventing membrane damage from oxidizing biocides.

First claim

1 . A method of preserving the effectiveness of a membrane in a water process flow, comprising the steps of:
adding a strong oxidizing biocide to process water, further downstream but upstream from the membrane adding a PAA bearing composition to the water, the PAA bearing composition being an oxidant but effectively reducing the oxidizing biocide so that the harm it causes the membrane is reduced by at least 50%, the method excluding the addition of a reducing agent in an amount capable of substantially neutralizing the oxidizing biocide so that the harm it causes the membrane is reduced by at least 50%.

2 . The method of claim 1 in which PAA bearing composition is eq-PAA which comprises 1-50% peroxide.

3 . A method of preserving the effectiveness of a membrane in a water process flow, comprising the steps of:
adding PAA to the water process flow upstream from the membrane in an amount sufficient to inhibit the growth of a biofilm on the filter.

4 . The method of claim 3 in which the PAA is eq-PAA which comprises 1-50% peroxide.

5 . The method of claim 3 further comprising the step of adding a strong oxidant and a reducing agent neutralizer to the water upstream from the addition of the PAA.

6 . The method of claim 5 in which the addition of reducing agent neutralizer would result in turning the water axonic but for the addition of the PAA.

7 . The method of claim 3 in which the water contains sufficient ionic or metallic particles that but for the presence of the PAA the water would turn axonic.

8 . The method of claim 7 further comprising the step of removing precipitated ions from the water.

9 . The method of claim 3 in which the water contains peroxide, the method further comprising contacting the peroxide with halogenated oxidant prior to its contact with the membrane, the contact resulting in the conversion of at least some of the peroxide into molecular oxygen and water.

10 . The method of claim 9 in which the oxygen is produced in an amount sufficient to reduce the population of microorganisms in the water.

11 . The method of claim 3 in which the water fed into the water process flow is one selected from the group consisting of: river water, sea water, desalinated water, brackish water, well water, aquifer water, pond water, wastewater, recirculated water, sewage water, purified water, de-oxygenated water, and any combination thereof.

12 . The method of claim 1 in which the membrane is one selected from the group consisting of: pressure-driven, microfiltration, ultrafiltration, nanofiltration, reverse osmosis, forward osmosis, electrodialysis, electrodeionization, pervaporation, membrane extraction, membrane distillation, membrane stripping, membrane aeration, submerged membrane, and any combination thereof.

13 . The method of claim 3 in which the PAA dosage to membrane system is in presence of antiscalants, pretreatment chemicals, etc.

14 . The method of claim 3 in which the membrane is in operation.

15 . A method of cleaning a membrane, the method comprising applying a clean in place effective amount of PAA to at least a portion of a membrane's surface and optionally rinsing the portion of the membrane's surface with a fluid.

16 . The method of claim 14 wherein the membrane is not in operation.

17 . The method of claim 1 further comprising the step of adding at least one scale inhibitor to the process water.

Assignees

• Ecolab Usa Inc

Inventors

• Gupta Amit
• Lohokare Harshada

Classifications

• C02F1/76

  with halogens or compounds of halogens {(C02F1/4674 takes precedence)} · CPC title

• C02F1/50 Primary

  by addition or application of a germicide or by oligodynamic treatment {(C02F1/4606, C02F1/467, C02F1/76 take precedence)} · CPC title

• C02F2103/32

  from the food or foodstuff industry, e.g. brewery waste waters · CPC title

• B01D65/08

  Prevention of membrane fouling or of concentration polarisation · CPC title

• B01D2321/168

  Use of other chemical agents · CPC title