# US 11,298,661 B2 · Cleaning method of a water-filtration system under operation

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- Number: US 11,298,661 B2
- Document ID: US11298661B2
- Status: Granted
- Kind: B2
- Application number: 16/314,571
- Filed: 2016-07-01
- Published: 2019-06-06
- Granted: 2022-04-12
- Earliest claimed: 2016-07-01
- Assignees: Total SA; Veolia Water Solutions & Technologies Support; Saipem S.P.A.
- Applicants: Total SA; Veolia Water Solutions & Technologies Support; Saipem S.A.
- Inventors: Jérôme Anfray; Pierre Pedenaud; Graeme Skivington; Thomas Delaplace
- Web page: https://patentgrep.com/patent/US11298661B2

## CPC

- B01D 65/02: Membrane cleaning or sterilisation {; Membrane regeneration}
- B01D 61/04: Feed pretreatment
- B01D 61/16: Feed pretreatment
- B01D 65/08: Prevention of membrane fouling or of concentration polarisation
- C02F 1/441: {by reverse osmosis}
- C02F 1/442: {by nanofiltration}
- C02F 1/444: {by ultrafiltration or microfiltration}
- B01D 2311/06: Specific process operations in the permeate stream
- B01D 2311/08: Specific process operations in the concentrate stream
- B01D 2311/12: Addition of chemical agents
- B01D 2311/24: Quality control
- B01D 2311/2512: to feed side
- B01D 2311/2523: to feed side
- B01D 2315/06: Submerged-type; Immersion type
- B01D 2315/10: Cross-flow filtration
- B01D 2321/16: Use of chemical agents
- B01D 2321/162: Use of acids
- B01D 2321/164: Use of bases
- B01D 2321/168: Use of other chemical agents
- B01D 2321/205: Integrated pumps
- B01D 2321/40: Automatic control of cleaning processes
- B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28)
- C02F: TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE (separation in general B01D; special arrangements on waterborne vessels of installations for treating water, waste water or sewage, e.g. for producing fresh water, B63J; adding materials to water to prevent corrosion C23F; treating radioactively-contaminated liquids G21F9/04; regeneration of reactants for recirculation into processes, see the relevant places for the processes)

## Abstract

The present invention is a filtration system and a method for cleaning a filtration system. The filtration system comprising a hydraulic circuit Cp recycling the permeate stream to the feed side of the membrane and/or a hydraulic circuit Cr recycling the retentate stream to the feed side of said membrane. The method injects an amount of a chemical product into the filtration system in the hydraulic circuit Cp or in the hydraulic circuit Cr or upstream of the cross-flow filtration membrane, setting the proportion of recycled permeate stream or recycled retentate stream collected in the hydraulic circuit Cp and/or Cr to enable the recycling of a significant amount of unreacted chemical product having passed through the cross-flow filtration membrane to the feed side of said cross-flow filtration membrane.

## Claims

### Claim 1

A method for cleaning a filtration system under operation, said filtration system comprising:
a cross-flow filtration membrane having:
a feed side fed with a feed stream,
a permeate side wherein a permeate stream is recovered and
a retentate side wherein a retentate stream is recovered,
a hydraulic circuit Cp being provided with a valve connecting the permeate side of said cross-flow filtration membrane to the feed side of said cross-flow filtration membrane, said hydraulic circuit Cp allowing recycling of a proportion of the permeate stream to the feed side of said cross-flow filtration membrane,
said method comprising:
measuring a difference in pressure between the feed side and the permeate side of the membrane, ΔP membrane, and/or measuring a difference in pressure between the feed side and the retentate side of the membrane, ΔP longitudinal,
injecting an amount of a chemical product into the filtration system which is under operation directly in the hydraulic circuit Cp when at least one of ΔP membrane and ΔP longitudinal reaches a predetermined value which is 10% higher than ΔP longitudinal initial or ΔP membrane initial,
setting a proportion of permeate stream collected in the hydraulic circuit Cp that is recycled to the feed side of said cross-flow filtration membrane with the valve to enable recycling of a significant amount of unreacted chemical product passing through said cross-flow filtration membrane, the significant amount of unreacted chemical product meaning that said unreacted chemical product is present in the recycled permeate stream at a concentration of at least 70% of initial concentration of chemical product injected directly into the hydraulic circuit Cp.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the cross-flow filtration membrane is a microfiltration membrane, an ultrafiltration membrane, a nanofiltration membrane or a reverse osmosis membrane.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the cross-flow filtration membrane is a ceramic membrane or an organic membrane.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the chemical product is a biocide, an acid, a base, a cleaning agent such as surfactant agent, a detergent, a complexation agent or a scale dissolver, or a mixture thereof.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the proportion of permeate stream collected in the hydraulic circuit Cp that is recycled to the feed side of the filtration a membrane is at least 10% relative to the flow rate of permeate stream collected ire the hydraulic circuit Cp.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the filtration system under operation is located under water.