# US 11,440,828 B2 · Method of treating sludge

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 11,440,828 B2
- Document ID: US11440828B2
- Status: Granted
- Kind: B2
- Application number: 16/954,762
- Filed: 2018-12-18
- Published: 2021-01-28
- Granted: 2022-09-13
- Earliest claimed: 2017-12-18
- Assignees: Veolia Water Solutions & Technologies Support
- Applicants: Veolia Water Solutions & Technologies Support
- Inventors: Hong W. Zhao; Sudhakar Viswanathan; Luther G. Wood; Brad Mrdjenovich; Richard W. DiMassimo; James McQuarrie
- Web page: https://patentgrep.com/patent/US11440828B2

## CPC

- C02F 11/04: Anaerobic treatment; Production of methane by such processes
- C02F 9/00: Multistage treatment of water, waste water or sewage
- C05F 7/005: {Waste water from industrial processing material neither of agricultural nor of animal origin}
- C05F 17/40: Treatment of liquids or slurries
- C05F 17/50: Treatments combining two or more different biological or biochemical treatments, e.g. anaerobic and aerobic treatment or vermicomposting and aerobic treatment
- C05F 17/60: Heating or cooling during the treatment
- C02F 1/5245: {using basic salts, e.g. of aluminium and iron}
- C02F 3/006: {Regulation methods for biological treatment}
- C02F 3/121: {Multistep treatment}
- C02F 3/1215: {Combinations of activated sludge treatment with precipitation, flocculation, coagulation and separation of phosphates}
- C02F 3/308: {Biological phosphorus removal}
- C02F 11/12: by de-watering, drying or thickening
- C02F 11/13: by heating
- C02F 11/18: by thermal conditioning (by pyrolysis C02F11/10)
- C02F 2101/10: Inorganic compounds
- C02F 2101/105: {Phosphorus compounds}
- C02F 2101/16: Nitrogen compounds, e.g. ammonia
- C02F 2209/02: Temperature
- C02F 2209/06: pH
- C02F 2209/14: NH3-N
- C02F 2209/18: PO4-P
- C02F 2209/40: Liquid flow rate
- C02F 2301/08: Multistage treatments, e.g. repetition of the same process step under different conditions
- Y02W 10/10: Biological treatment of water, waste water, or sewage
- 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)
- C05F: ORGANIC FERTILISERS NOT COVERED BY SUBCLASSES C05B, C05C, e.g. FERTILISERS FROM WASTE OR REFUSE
- Y02W: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT

## Abstract

The present invention relates to a method of treating sludge containing phosphorus, ammonia and magnesium and enhancing the dewaterability of the sludge. The sludge is directed into a biological fermenter operated under anaerobic conditions. By controlling the temperature of the sludge in the fermenter or the hydraulic retention time of the sludge in the fermenter, phosphorus, ammonia and magnesium is released from the solids in the sludge into a liquid forming a part of the sludge. Sludge from the fermenter is subjected to a solids-liquid separation process that produces a concentrated sludge and a liquid. The concentrated sludge or separated solids is directed to a thermal hydrolysis reactor that thermally hydrolyzes the concentrated sludge. After thermally hydrolyzing the concentrated sludge, the concentrated sludge is directed to an anaerobic digester that anaerobically digests the concentrated sludge.

## Claims

### Claim 1

A method of treating sludge including solids containing phosphorus, ammonia and magnesium and enhancing the dewaterability of the sludge, comprising:
directing the sludge to a biological fermenter;
biologically treating the sludge in the biological fermenter which is operated under anaerobic conditions;
causing the solids to release phosphorus, ammonia and magnesium into a liquid forming a part of the sludge by maintaining: (1) the temperature of the sludge in the fermenter to a temperature within the range of 50° C.-70° C.; and (2) controlling the hydraulic retention time of the sludge in the fermenter to approximately 6 to approximately 10 hours;
directing the sludge from the fermenter to a solids-liquid separator;
separating the solids from the liquid containing the released phosphorus, ammonia and magnesium;
directing the separated solids to a thermal hydrolysis reactor and thermally hydrolyzing the separated solids; and
after thermally hydrolyzing the separated solids, directing the hydrolyzed separated solids to an anaerobic digester and anaerobically digesting the hydrolyzed separated solids.

### Claim 2 (depends on 1)

The method of claim 1 wherein the method includes mixing the liquid containing the released phosphorus, ammonia and magnesium with the anaerobically digested solids to form a mixture and directing the mixture to a MAP process located downstream of the anaerobic digester and forming struvite in the MAP process.

### Claim 3 (depends on 1)

The method of claim 1 wherein the method includes directing the liquid containing the released phosphorus, ammonia and magnesium to a struvite reactor and producing struvite.

### Claim 4 (depends on 1)

The method of claim 1 including heating and pasteurizing the liquid containing the released phosphorus, ammonia and magnesium; and after heating the liquid, directing the pasteurized liquid to: (1) a MAP process located downstream of the anaerobic digester and producing struvite or (2) directly to a struvite production process.

### Claim 5 (depends on 4)

The method of claim 4 including directing the pasteurized liquid directly to a struvite production process and producing struvite, and thereafter thermally drying the struvite.

### Claim 6 (depends on 1)

The method of claim 1 including heating the sludge prior to the sludge reaching the biological fermenter in a dynamic mixer or heat exchanger located upstream of the biological fermenter.

### Claim 7 (depends on 1)

The method of claim 1 including facilitating the release of phosphorus, ammonia and magnesium from the solids into the liquid by controlling the pH of the sludge in the biological fermenter to approximately 4-5.

### Claim 8 (depends on 1)

The method of claim 1 including dewatering the anaerobically digested sludge produced by the anaerobic digester.

### Claim 9 (depends on 1)

The method of claim 1 including monitoring the concentration of the phosphorus and ammonia released from the solids and controlling the temperature of the sludge in the biological fermenter and/or controlling the HRT of the sludge in the fermenter so as to maintain a mole ratio of the ammonia to the phosphorus of approximately 1.0-1.5.

### Claim 10 (depends on 1)

The method of claim 1 including seeding the sludge with anaerobically digested sludge from the anaerobic digester by transferring sludge from the anaerobic digester to the biological fermenter or to a point upstream of the biological fermenter.

### Claim 11 (depends on 1)

The method of claim 1 including heating the sludge prior to directing the sludge to the biological fermenter.

### Claim 12 (depends on 11)

The method of claim 11 wherein anaerobically digesting the hydrolyzed separated solids produces anaerobically digested sludge; and wherein the method includes recycling a portion of the anaerobically digested sludge and mixing the portion of anaerobically digested sludge with the liquid containing the phosphorus, ammonia and magnesium to form a mixture.

### Claim 13 (depends on 12)

The method of claim 12 including directing the mixture to a MAP process located downstream of the anaerobic digester and forming struvite in the MAP process.

### Claim 14

A method of treating sludge including solids containing phosphorus, ammonia and magnesium and enhancing the dewaterability of the sludge, comprising:
directing the sludge to a biological fermenter;
biologically treating the sludge in the biological fermenter which is operated under anaerobic conditions;
causing the solids to release phosphorus, ammonia, and magnesium into a liquid forming a part of the sludge by maintaining: (1) the temperature of the sludge in the fermenter to a temperature within the range of 50° C. -70° C.; and (2) controlling the hydraulic retention time of the sludge in the fermenter to approximately 6 to approximately 10 hours;
directing the sludge from the fermenter to a solids-liquid separator;
separating the solids from the liquid containing the released phosphorus, ammonia and magnesium; and
directing the separated solids to a thermal dryer and drying the solids.

### Claim 15 (depends on 14)

The method of claim 14 including:
pasteurizing the liquid containing the phosphorus, ammonia and magnesium; and
after pasteurizing the liquid containing the phosphorus, ammonia and magnesium,
directing the liquid to a struvite production facility and producing struvite.

### Claim 16 (depends on 14)

The method of claim 14 further including:
pasteurizing the liquid containing the phosphorus, ammonia and magnesium; and
directing the liquid containing the phosphorus, ammonia and magnesium to a struvite production facility and producing struvite and thereafter thermally drying the produced struvite.