# US 10,118,850 B2 · Process for the treatment of a flow of waste water by low-pressure filtration

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- Number: US 10,118,850 B2
- Document ID: US10118850B2
- Status: Granted
- Kind: B2
- Application number: 15/321,789
- Filed: 2015-06-23
- Published: 2017-05-11
- Granted: 2018-11-06
- Earliest claimed: 2014-06-27
- Assignees: Veolia Water Solutions & Technologies Support
- Applicants: Veolia Water Solutions & Technologies Support
- Inventors: Abdelkader Gaid; Catherine Daines-Martinez; Sebastien Logette; Christophe Amiel
- Web page: https://patentgrep.com/patent/US10118850B2

## CPC

- C02F 9/00: Multistage treatment of water, waste water or sewage
- B01D 61/58: Multistep processes
- B01D 65/08: Prevention of membrane fouling or of concentration polarisation
- C02F 1/444: {by ultrafiltration or microfiltration}
- C02F 1/683: {by addition of complex-forming compounds}
- C02F 5/14: containing phosphorus
- B01D 61/025: {Reverse osmosis; Hyperfiltration}
- B01D 61/027: {Nanofiltration}
- B01D 61/145: {Ultrafiltration}
- B01D 61/147: {Microfiltration}
- B01D 2311/12: Addition of chemical agents
- B01D 2311/2688: Biological processes
- B01D 2315/10: Cross-flow filtration
- C02F 1/441: {by reverse osmosis}
- C02F 1/442: {by nanofiltration}
- C02F 3/302: {Nitrification and denitrification treatment (C02F3/308 takes precedence)}
- C02F 3/307: {characterised by direct conversion of nitrite to molecular nitrogen, e.g. by using the Anammox process}
- C02F 11/04: Anaerobic treatment; Production of methane by such processes
- C02F 2101/105: {Phosphorus compounds}
- C02F 2101/16: Nitrogen compounds, e.g. ammonia
- C02F 2101/20: Heavy metals or heavy metal compounds
- C02F 2101/32: Hydrocarbons, e.g. oil
- C02F 2303/10: Energy recovery
- C02F 2303/16: Regeneration of sorbents, filters
- C02F 2303/24: Separation of coarse particles, e.g. by using sieves or screens
- Y02E 50/30: Fuel from waste, e.g. synthetic alcohol or diesel
- Y02W 10/30: Wastewater or sewage treatment systems using renewable energies
- 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)
- 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)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

In order to treat a flow of waste water, there is applied to this flow, after at most an optional pre-treatment of screening/degritting or deoiling, a filtration treatment by means of microfiltration or ultrafiltration membranes, by causing the flow to circulate tangentially to the membranes at a velocity of at least 0.1 m/s, in the presence of an organic sequestering agent composed based on organic phosphate at a concentration that is effective for sequestering metal ions contained in the flow and minimizing the formation of calcium carbonate, with a differential pressure on either side of the membranes that is less than or equal to 5 bar.

## Claims

### Claim 1

A method of treating water comprising:
pre-treating the water;
after pre-treating the water, directing the water to and through one or more microfiltration or ultrafiltration membranes and producing a first permeate and a first concentrate;
flowing the water tangentially to the microfiltration or ultrafiltration membranes at a velocity of at least 0.1 m/s;
mixing an organic sequestering agent with the water at or upstream of the microfiltration or ultrafiltration membranes and wherein the sequestering agent comprises organic phosphonates;
mixing a sufficient amount of organic phosphonates with the water to achieve a concentration that is effective for sequestering metal ions contained in the water and minimizing the formation of calcium carbonate;
after sequestering the metal ions and minimizing the formation of calcium carbonate, adsorbing the organic phosphonates onto the suspended solids in the water;
maintaining a differential pressure across the microfiltration or ultrafiltration membranes that is less than or equal to 5 bar;
directing the first permeate to and through one or more nanofiltration or reverse osmosis membranes to produce a second permeate and a second concentrate;
directing the first concentrate to a first anaerobic digester and anaerobically digesting the first concentrate; and
directing the second concentrate to the first anaerobic digester or to a second anaerobic digester and anaerobically digesting the second concentrate.

### Claim 2 (depends on 1)

The method of claim 1 including maintaining the concentration of organic phosphonate in the water flowing across the microfiltration or ultrafiltration membranes at 0.25 mg/L to 4 mg/L.

### Claim 3 (depends on 2)

The method of claim 2 wherein there is provided a biological reactor operatively connected to at least one of said anaerobic digesters and which includes fixed bacteria and wherein the method includes removing nitrogen produced in the anaerobic digester from the concentrate therein.

### Claim 4

A method of treating water containing suspended solids and metal ions comprising:
pre-treating the water;
after pre-treating the water, directing the water to and through one or more microfiltration or ultrafiltration membranes and producing a first permeate and a first concentrate;
flowing the water tangentially to the microfiltration or ultrafiltration membranes at a velocity of at least 0.1 m/s;
mixing an organic sequestering agent with the water at or upstream of the microfiltration or ultrafiltration membranes and wherein the sequestering agent comprises organic phosphonates;
mixing a sufficient amount of organic phosphonates with the water to achieve a concentration that is effective for sequestering metal ions contained in the water and minimizing the formation of calcium carbonate;
after sequestering the metal ions and minimizing the formation of calcium carbonate, adsorbing the organic phosphonates onto the suspended solids in the water; and
maintaining a differential pressure across the microfiltration or ultrafiltration membranes that is less than or equal to 5 bar.

### Claim 5

A method of treating water containing suspended solids and metal ions comprising:
filtering the water in one or more microfiltration or ultrafiltration membranes while maintaining the differential pressure on either side of the membrane less than or equal to 5 bar to generate a first permeate and a first concentrate;
flowing the water tangentially to the microfiltration or ultrafiltration membranes at a velocity of at least 0.1 m/s during said filtering;
mixing an organic sequestering agent comprising organic phosphonates with the water at or upstream of the microfiltration or ultrafiltration membranes at a concentration effective for sequestering metal ions contained in the water and minimizing the formation of calcium carbonate; and
filtering at least a portion of the first permeate in one or more nanofiltration or reverse osmosis membranes to produce a second permeate and a second concentrate.

### Claim 6 (depends on 5)

The method according to claim 5, in which the addition of the sequestering agent promotes the capture of metal ions, prevents the precipitation of calcium carbonate and promotes the filtration of water through the pores of the membrane.

### Claim 7 (depends on 5)

The method according to claim 5, further comprising maintaining the concentration of organic phosphonate in the water flowing across the microfiltration or ultrafiltration membranes at 0.25 mg/L to 4 mg/L.

### Claim 8 (depends on 5)

The method according to claim 5, further comprising anaerobically digesting the first concentrate in a first anaerobic digester to produce a biogas.

### Claim 9 (depends on 8)

The method according to claim 8, further comprising converting the biogas into energy that can be used on site.

### Claim 10 (depends on 8)

The method according to claim 8, further comprising removing nitrogen produced in the anaerobic reactor in a biological reactor constituted by fixed bacteria.

### Claim 11 (depends on 10)

The method according to claim 10, in which the biological reactor with fixed bacteria is a moving bed bioreactor or MBBR so as to combine nitration and anoxic oxidation of ammonia through the development of a biofilm on a plastic support moved by agitation or aeration.

### Claim 12 (depends on 5)

The method of claim 5 wherein the water comprises a raw water and wherein the filtering of the raw water in one or more microfiltration or ultrafiltration membranes is performed with no pre-treatment of the raw water except for de-oiling and screening.