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Method for desalting sewage by using membrane separation technology

A membrane separation and sewage technology, applied in chemical instruments and methods, water/sewage multi-stage treatment, water/sludge/sewage treatment, etc., can solve the problems of low water production rate, long pretreatment process, membrane pollution, etc. Achieve the effect of reducing pollution, low hardness of produced water and stable operation

Inactive Publication Date: 2014-03-26
CHINA PETROLEUM & CHEM CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] Therefore, reverse osmosis or nanofiltration desalination in the prior art has the characteristics of serious membrane fouling, low water production rate, and long pretreatment process.

Method used

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  • Method for desalting sewage by using membrane separation technology
  • Method for desalting sewage by using membrane separation technology
  • Method for desalting sewage by using membrane separation technology

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] like figure 1 As mentioned above, the reverse osmosis concentrated water after reuse of sewage from a petrochemical enterprise enters the stirring reaction tank 1, and sodium hydroxide is added to adjust the pH to 10.4-11.0. Microfiltration tubular membrane filter 4. The microfiltration tubular membrane 3 has a pore size of 0.2 μm, and the filtration method is dead-end filtration. The produced water enters the water production tank 6 and enters the reverse osmosis system through the pump 7, and the concentrated water enters the sludge tank through the slag discharge pipeline 5. The reverse osmosis water production rate is 67-85%. See attached table 1 for the water quality, microfiltration and reverse osmosis treatment effects.

[0030] Table 1

[0031]

Embodiment 2

[0033] like figure 2 As shown, a certain oilfield sewage enters the stirring reaction tank 10, and sodium hydroxide is added to adjust the pH to 9.5 to 10.2, and sodium carbonate is added according to the molar ratio of calcium, magnesium and carbonate of 1:1.1 to 1.3, and the stirring time is 1 hour respectively. The 2-stage mixing and stirring is transported to the internal pressure type microfiltration tube type microfiltration membrane 30 through the pump 20, the membrane pore size is 0.1 μm, the filtration method is cross-flow filtration, the control flux is 400-800LMH, the cross-flow rate is 260-400%, and the filtration The last concentrated water enters the concentrated water tank 50 and enters the sludge thickening tank through the slag discharge pipeline 70 . The water produced by the microfiltration enters the water production tank 40, and enters the reverse osmosis system through the pump 60, and the reverse osmosis water production rate is 60-70%. See attached ta...

Embodiment 3

[0037] Calcium hydroxide was added to the sewage of a coal chemical industry to adjust the pH to 9.3-10.5. Carbon dioxide is added according to the molar ratio of calcium, magnesium and carbonate of 1:1.1-1.5. After 2-stage mixing and stirring with a stirring time of 40 minutes, it was lifted to a microfiltration hollow fiber filter by a pump. The pore size of the microfiltration membrane is 0.2 μm, the filtration method is dead-end filtration, and the concentrated water is discharged to the sludge tank. The water produced by microfiltration enters the reverse osmosis system, and the water production rate is 65-74%. See attached table 3 for the water quality, microfiltration and reverse osmosis treatment effects.

[0038] table 3

[0039] Analysis Project

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Abstract

The invention discloses a method for desalting sewage by using a membrane separation technology. The method comprises the following steps: (1) adding sewage into a stirred reaction tank, adding sodium hydroxide or calcium hydroxide, adjusting the pH value to 9.0-11.5, and carrying out stirred reaction for 40-110min; (2) carrying out hardness removal pretreatment on a mixed solution after reaction by using a microfiltration membrane, wherein the microfiltration membrane has the aperture of 0.1-0.2mum, and dead end or cross flow filtration is used as a filtration way; (3) enabling the pretreated concentrated water to enter a concentration tank or residue pond; (4) pressurizing the pretreated production water, and desalting the pretreated production water in a reverse osmosis system or nanofiltration system. The reverse osmosis or pretreatment of a nanofiltration membrane is realized through hardness removal by using the microfiltration membrane, the production water is good in quality and good in hardness removal effect, and the reverse osmosis or scaling pollution of a nanofiltraiton membrane is reduced; the microfiltrated concentrated water is high in suspended matter content and convenient for dehydration treatment; the reverse osmosis or nanofiltration can be carried out under slightly alkaline conditions, so that pollution form organic matters and microorganisms can be reduced.

Description

technical field [0001] The invention relates to the field of wastewater treatment and recycling, in particular to a method for demineralizing wastewater using membrane separation technology. Background technique [0002] In sewage treatment and recycling, organic sewage after certain treatment is often desalinated by reverse osmosis (RO) or nanofiltration (NF) membrane separation technology to meet the water quality requirements for sewage reuse. Since the sewage contains pollutants such as organic matter and hardness, it will affect the stable operation of the membrane and the water production rate. Usually, the method of lime softening and adding scale inhibitor is used to reduce membrane scaling, and at the same time, biological, physicochemical and other methods are used to further reduce organic matter, so as to reduce the pollution of organic matter and microorganisms. In addition, the pretreatment of reverse osmosis membrane usually has ultrafiltration (UF) to achiev...

Claims

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Application Information

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IPC IPC(8): C02F9/04C02F1/44
Inventor 刘正彭海珠孙杰赵辉龚小芝
Owner CHINA PETROLEUM & CHEM CORP
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