Method and system for treating brine waste water

Patent metadata

Field	Value
Publication number	US-10669168-B2
Application number	US-201715807252-A
Country	US
Kind code	B2
Filing date	Nov 8, 2017
Priority date	Nov 29, 2016
Publication date	Jun 2, 2020
Grant date	Jun 2, 2020

Abstract

The present invention relates to a method for zero-release treatment of brine waste water, comprising: (1) pretreatment; (2) reverse osmosis treatment; (3) advanced oxidation treatment; (4) biochemical treatment; (5) electrodialysis concentration; (6) circulating crystallization. Compared with the prior art, the method for zero-release treatment of brine waste water provided in the present invention realizes zero release or near zero release of waste water, improves salt recovery efficiency, can recover high-quality sodium sulfate, mirabilite and sodium chloride, and turns crystalline salts into a resource; the membrane treatment unit can operates stably in the process for a long operation period at a low cost, and the entire process has high economic efficiency.

First claim

The invention claimed is:

1. A method for treatment of brine waste water, comprising:
(1) a pretreatment step wherein the brine is subject to softening, coagulation and sedimentation, rough filtration, and ultrafiltration to obtain a pretreated brine;
(2) a reverse osmosis treatment step that comprises passing the pretreated brine to an intermediate pressure reverse osmosis filter to produce a first diluted water and a first concentrate water, passing the first concentrate water to a high pressure reverse osmosis filter to produce a second diluted water and a second concentrate water;
(3) a biochemical treatment step that comprises treating the second concentrate water in a membrane bioreactor containing a salt-tolerant microbial inoculum and a microbial growth promoter to reduce a COD value and a total nitrogen concentration in the second concentrate water and discharging the bio-treated water from the membrane bioreactor;
(4) an electrodialysis concentration step that comprises subjecting the bio-treated water obtained from step (3) to softening, coagulation and sedimentation, rough filtration, and ultrafiltration to produce a filtered, bio-treated water; and electrodialyzing the filtered, bio-treated water to produce a third diluted water and a third concentrate water;
combining the third diluted water and the first concentrate water to produce a feed water for the high pressure reverse osmosis filter; and subjecting the third concentrate water to a crystallization step to obtain crystallized salts.

2. The method according to claim 1 , wherein the high pressure reverse osmosis filter and the intermediate pressure reverse osmosis filter are operated at a pressure differential of 0.5-5 MPa.

3. The method according to claim 2 , wherein an operating pressure of the intermediate pressure reverse osmosis filter is 0.5-5 MPa.

4. The method according to claim 1 , further comprising oxidizing the second concentrate water from the high pressure reverse osmosis filter in a Fenton reaction to decrease a COD value by 20% or more and to increase a B/C value by 50% or more.

5. The method according to claim 1 , wherein the biochemical treatment step reduces, in the second concentrate water, ammonium-nitrogen by 90% or more, decreases the COD value to 200 mg/L or less, and decreases a nitrate nitrogen concentration to 50 mg/L or lower.

6. The method according to claim 1 , wherein the biochemical treatment is carried out in the presence of a salt-tolerant microbial inoculum and a microbial growth promoter, the salt-tolerant microbial inoculum contains Kocuria palustris FSDN-A and/or Staphylococcus cohnii FSDN-C, and Paracoccus denitrificans DN-3 and/or Methylobacterium phyllosphaerae SDN-3, wherein, the Kocuria palustris FSDN-A and Staphylococcus cohnii FSDN-C are being preserved in China General Microbiological Culture Collection Center (CGMCC) on Jul. 14, 2011 and numbered as CGMCC No. 5061 and CGMCC No. 5062, respectively, the Paracoccus denitrificans DN-3 and Methylobacterium phyllosphaerae SDN-3 are being preserved in CGMCC and numbered as CGMCC No. 3658 and CGMCC No. 3660, respectively,
wherein a quantity of the salt-tolerant microbial inoculum is 0.01-0.1 vol % of the waste water to be treated by biochemical treatment.

7. The method according to claim 1 , wherein the microbial growth promoter comprises a metal salt, a polyamine, and an organic acid hydroxylamine, and a weight ratio of the metal salt to the polyamine to the organic acid hydroxylamine is 40-100:5-30:0.5-15, wherein a concentration of the microbial growth promoter in the waste water to be treated by biochemical treatment is 1-20 mg/L.

8. The method according to claim 7 , wherein the weight ratio of the metal salt to the polyamine to the organic acid hydroxylamine is 50-80:10-20:2-10, and the concentration of the microbial growth promoter is 5-15 mg/L.

9. The method according to claim 1 , wherein, in the membrane bioreactor, a concentration of an activated sludge inoculum is 3,000-5,000 mg/L, a concentration of dissolved oxygen is 1-5 mg/L, a pH value is 7-9, a temperature is 20-40° C., and an hydraulic retention time is 3-12 h.

10. The method according to claim 1 , wherein, after the electrodialysis treatment step, the third concentrate water has a TDS of 200,000 mg/L or higher, an ammonia nitrogen content of 50 mg/L or lower, a TDS in the third diluate water of 25,000 mg/L or lower, and an ammonia nitrogen content in the third diluted water of 5 mg/L or lower.

11. The method according to claim 1 , wherein the brine contains sodium sulfate and sodium chloride, and the crystallization step comprises: treating the third concentrate water by a primary evaporative crystallization to obtain sodium sulfate crystals and a primary mother liquid, freezing the primary mother liquid to obtain mirabilite and secondary mother liquid, and treating the secondary mother liquid by a secondary evaporative crystallization to obtain sodium chloride crystals and a tertiary mother liquid.

12. The method according to claim 11 , wherein, in the primary evaporative crystallization, evaporation is carried out at a temperature of 50° C. to 150° C. and crystallization is carried out at a temperature of 50° C. to 100° C., freezing the primary mother liquid is carried out at −8° C. to 0° C., and, in the secondary evaporative crystallization, evaporation is carried out at a temperature of 50° C. to 150° C. and crystallization is carried out at a temperature of 30° C. to 50° C.

13. The method according to claim 1 , wherein, in the brine, a COD value is 60-200 mg/L, a total hardness measured in CaCO 3 is 1,000-2,500 mg/L, a total alkalinity measured in CaCO 3 is 500-2,000 mg/L, a TDS value is 2,000-10,000 mg/L, an ammonia nitrogen concentration is 5-50 mg/L, and a nitrate nitrogen concentration is 20-100 mg/L.

Assignees

• China Petroleum & Chem Corp
• Fushun Res Institute Of Petroleum And Petrochemicals Sinopec Corp

Inventors

• Gao Huijie
• Sun Danfeng
• Guo Zhihua
• Chen Mingxiang

Classifications

• C02F1/586

  by removing ammoniacal nitrogen (for biological methods C02F3/00) · CPC title

• C02F3/1268

  Membrane bioreactor systems · CPC title

• C02F2301/08

  Multistage treatments, e.g. repetition of the same process step under different conditions · CPC title

• C02F5/00

  Softening water; Preventing scale; Adding scale preventatives or scale removers to water, e.g. adding sequestering agents (softening using ion-exchange C02F1/42) · CPC title

• C02F1/444 Primary

  by ultrafiltration or microfiltration · CPC title