Elimination of sodium sulfate from biologically treated wastewater

Patent metadata

Field	Value
Publication number	US-9908801-B2
Application number	US-201414261931-A
Country	US
Kind code	B2
Filing date	Apr 25, 2014
Priority date	Apr 26, 2013
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

The application relates to a process comprising: treating a wastewater stream in a membrane bioreactor, treating the effluent from the previous step in a cationic on exchanger, and treating the effluent from the previous step in a nanomembrane filter.

First claim

What is claimed is:

1. A process comprising:
a. treating a wastewater stream from a hydroxyl-propylated starch production process having high organic content and sodium sulfate in a membrane bioreactor,
b. b) treating the effluent from step a) in a cationic ion exchanger, and
c. c) treating the effluent from step b) in a nanofiltration unit to produce an effluent and a retentate,
d. d) treating the wastewater stream in an aerobic biological system prior to step a);
wherein the sodium sulfate content of the effluent of step c) has been reduced to a concentration of less than 235 mg/L;
wherein the nanofiltration unit concentrates sodium sulfate in the retentate such that sodium sulfate can be recovered from the retentate as sodium sulfate decahydrate at a purity of greater than 99%;
wherein the sodium sulfate decahydrate is recycled back into the hydroxyl-propylated starch production processing;
and wherein the nanofiltration unit comprises a nanomembrane filter having a molecular weight cut-off of from about 200 Daltons to about 500 Daltons.

2. The process of claim 1 wherein the membrane pore size of the membrane bioreactor is from about 1 μm to about 0.02 μm.

3. The process of claim 2 wherein the membrane pore size is from about 0.4 μm to about 0.03 μm.

4. The process of claim 1 wherein the membrane of the membrane bioreactor is of tubular configuration, spiral configuration, hollow fiber configuration, or flat sheet configuration.

5. The process of claim 1 wherein the transmembrane pressure of the membrane bioreactor is from about 10 kPa to about 600 kPa.

6. The process of claim 1 wherein the cationic ion exchanger is of the carboxylic acid, amniophosphonic acid, iminodiacetic acid, or sulfonic acid type.

7. The process of claim 6 wherein the cationic ion exchanger is in the sodium form.

8. The process of claim 1 wherein the pressure drop in the nanomembrane filter is from about 1 kPa to about 4000 kPa.

9. The process of claim 1 wherein the temperature of the process from about 15° C. to about 45° C.

10. The process of claim 1 wherein the isolation is by a crystallization process.

11. The process of claim 10 wherein the temperature of the crystallization process is from about 0° C. to about 5° C.

12. The process of claim 10 wherein the sodium sulfate decahydrate is isolated in a centrifuge.

13. The process of claim 12 further comprising passing the filtrate from the centrifuge through a cationic ion exchanger and through a granulated active carbon unit.

14. The process of claim 1 further comprising treating the effluent from step c) in a chiller/crystallizer system.

15. The process of claim 14 further comprising treating the effluent from the chiller/crystallizer system in a centrifuge.

Assignees

• Corn Products Dev Inc

Inventors

• Gonzalez Carlos Eduardo Hurtado

Classifications

• C02F2001/425

  using cation exchangers · CPC title

• C02F2101/30

  Organic compounds · CPC title

• C02F1/52

  by flocculation or precipitation of suspended impurities {(C02F1/463 takes precedence)} · CPC title

• C02F1/283

  using coal, charred products, or inorganic mixtures containing them · CPC title

• C02F1/385

  by centrifuging suspensions (centrifuges B04B) · CPC title