Method for recovering N, K, and P from liquid waste stream

Patent metadata

Field	Value
Publication number	US-11577959-B2
Application number	US-201816499925-A
Country	US
Kind code	B2
Filing date	Mar 30, 2018
Priority date	Apr 6, 2017
Publication date	Feb 14, 2023
Grant date	Feb 14, 2023

Abstract

The present invention relates to a method for recovering N, K, and P from liquid waste stream, preferably from a stream of urine, or from a stream comprising excreta (e.g. faeces, manure, digestate, fertilizer), or from (concentrated) wastewater, for example, municipal (e.g. sewage, septic) and/or industrial wastewater (e.g. food and feed industry, agriculture, mining, etc.); more preferably from urine, such as human or animal urine; most preferably from human urine.

First claim

The invention claimed is:

1. Method for recovering Nitrogen (N), Potassium (K), and Phosphorus (P) from a liquid waste stream, wherein the liquid waste stream comprises N, K, and P, the method comprising the steps of: a. removing a Nitrogen (N)-comprising compound from the liquid waste stream, thereby obtaining a Nitrogen (N)-poor solution and the Nitrogen (N)-comprising compound; wherein during step a. the concentration of Nitrogen (N) in the Nitrogen (N)-poor solution is at most 100.0 mg/l, as measured using a Kjeldahl measurement method according to ISO 5663:1984; b. concentrating the Nitrogen (N)-poor solution through water removal, thereby obtaining a concentrated solution; wherein step b. is performed until the water removal is at least 50.0%; c. adding a nucleating agent to the concentrated solution; and, d. precipitating potassium struvite MgKPO 4. 6H 2 0 from the concentrated solution, thereby obtaining potassium struvite MgKPO 4 .6H 2 O and a waste solution, wherein step a. and/or step b. is performed through membrane distillation and wherein in step d. no magnesium ammonium phosphate (ammonium struvite, MAP) is formed.

2. Method according to claim 1 , wherein the liquid waste stream is a stream of urine, or is a stream comprising excreta, or is wastewater.

3. Method according to claim 1 , wherein during step a. at least 80.0% of reduced Nitrogen (N), in which Nitrogen (N) has a negative oxidation state, is removed, with the % based on the total amount of Nitrogen (N) in the liquid waste stream as measured using the Kjeldahl measurement method according to ISO 5663:1984.

4. Method according to claim 1 , wherein the pH of the liquid waste stream is at least 7 to at most 14.

5. Method according to claim 1 , wherein during step a. the concentration of Nitrogen (N) in the Nitrogen (N)-poor solution is at most 75.0 mg/l.

6. Method according to claim 1 , wherein the Nitrogen (N)-comprising compound is an organically bound Nitrogen (N)-compound.

7. Method according to claim 1 , wherein step b. is performed until the concentrated solution contains a Phosphorus (P) concentration of at least 50 mg/l.

8. Method according to claim 1 , wherein step b. is performed until the water removal is at least 50.0% and at most 99.0%; wherein 100.0% is the total amount of water present in the Nitrogen (N)-poor solution.

9. Method according to claim 1 , wherein the nucleating agent is a Magnesium (Mg)-comprising compound or solution.

10. Method according to claim 1 , wherein an average dosage speed of Magnesium (Mg) concentration added to the concentrated solution is adjusted to the Phosphorus (P) concentration in concentrated solution.

11. Method according to claim 1 , wherein the Potassium to Phosphorus (K:P) molar ratio in the liquid waste stream is at least 0.5:1.

12. Method according to claim 1 , wherein none of Nitrogen (N), Potassium (K), or Phosphorus (P) are added to the liquid waste stream prior to step a., and/or to the Nitrogen (N)-poor solution prior to step b., and/or to the concentrated solution prior to step c.

Assignees

• Univ Gent

Inventors

• Verliefde Arne
• Derese Sebastiaan

Classifications

• C02F1/442

  by nanofiltration · CPC title

• C02F1/66

  by neutralisation; pH adjustment (for degassing C02F1/20; using ion-exchange C02F1/42; for flocculation or precipitation of suspended impurities C02F1/52; for removing dissolved compounds C02F1/58) · CPC title

• C02F2101/105

  Phosphorus compounds · CPC title

• C02F2103/20

  from animal husbandry · CPC title

• C02F2001/5218

  Crystallization · CPC title