CN108704484A - A kind of membrane contactor separation method for polynary pollutant aqueous solution - Google Patents

Abstract

The present invention provides a kind of membrane contactor separation methods for polynary pollutant aqueous solution, belong to technical field of wastewater recovery, and the pollutant refers in particular to the compound more more volatile than water.Vacuum pump is used to generate cross-film steam pressure difference as motive force, feeding temperature that can by separation volatile compounds and water two steps or osmotic lateral pressure difference realization separation different with the saturated vapour pressure of water using volatile compounds in pollutant in system.By regulating and controlling the temperature setting of heating device or the pressure setting of vacuum pump, you can reach separating effect.

Description

A Membrane Contactor Separation Method for Multiple Pollutant Aqueous Solutions

technical field

The invention relates to a membrane contactor separation method for an aqueous solution of multiple pollutants. The pollutants specifically refer to compounds that are more volatile than water. The device is suitable for the effective recovery and standard discharge of the aqueous solution.

Background technique

Multi-pollutant aqueous solution is a common wastewater in chemical production. In order to meet the national environmental protection requirements, it is particularly important to effectively recover and discharge the aqueous solution up to the standard.

At present, the main treatment methods for aqueous solutions containing multiple pollutants include microbial degradation, air stripping, pervaporation and adsorption. However, the microbial degradation method has certain limitations for highly toxic wastewater. The gas extraction method requires a large amount of gas and has uneven gas-liquid contact. The membrane used in pervaporation is expensive and easy to foul on the surface. The adsorption method has renewal replacement. High cost, low regeneration efficiency and other problems.

Membrane contactor is a new type of hybrid membrane process that realizes mass transfer through membrane as the separation interface between gas and liquid phases. The specific application forms include membrane distillation, membrane extraction, membrane absorption, etc., which can realize gas-liquid separation Divide and concentrate two functions. Membrane distillation uses a hydrophobic microporous membrane as the gas-liquid separation interface, and the volatile components are volatilized in gaseous form, and pass through the membrane pores to reach the permeate side under the transmembrane vapor pressure difference to achieve the separation effect. Vacuum membrane distillation uses a vacuum pump to generate a certain degree of vacuum on the permeate side, forming a transmembrane vapor pressure difference between the feed side and the permeate side, as a driving force to complete the separation.

In the Chinese patent CN102989197A, it is mentioned that the method of gas stripping is used to remove the gas in the solution, but this method needs to feed nitrogen or air, and there will be uneven gas distribution, resulting in poor final removal effect. In the Chinese patent CN105217861A, a treatment method for reverse osmosis concentrated water is mentioned. The nanofiltration membrane is used to remove gas, the nanofiltration water is concentrated by reverse osmosis, and then enters the membrane distillation system for treatment and reuse after concentration. The process of this method is cumbersome. And it has higher requirements on the membrane used in the process.

Contents of the invention

The invention belongs to the field of industrial waste water recovery, and in particular relates to a comprehensive separation and recovery method and system for an aqueous solution containing multiple pollutants produced in a chemical production process. Using the membrane distillation method, the volatile compounds in the pollutants and the saturated vapor pressure of water are different, and the separation is achieved through the difference in the feed temperature or permeate side pressure in the two steps, so as to realize the effective recovery and standard discharge of wastewater.

Technical scheme of the present invention:

A membrane contactor separation method for multi-pollutant aqueous solution, the separation system used includes a membrane contactor and two sets of condensing devices; one set of condensing devices is used to separate volatile compounds in the feed liquid, and the other set of condensing The device is used to separate the moisture in the feed liquid, and the separation is achieved by the feed temperature or the pressure of the permeate side in the two steps. The steps are as follows:

Different feed temperature to achieve separation:

(1) Stirring device 2 is installed in the raw material tank 1 with a jacket. After the raw material liquid is heated to 30°C-55°C by the temperature control device 3, the circulating pump 4 passes the raw material liquid through the valve 5, the thermometer 6 and the first The pressure gauge 7 is sent to the membrane contactor 8, the liquid on the retentate side is circulated back to the raw material tank 1, the compressor 10, the first vacuum pump 15 and the first condenser 12 are turned on, and the transmembrane vapor pressure difference generated by the first vacuum pump 15 is used As a driving force, the volatile compounds permeate through the membrane holes, pass through the second pressure gauge 9, the compressor 10 and the third pressure gauge 11 in turn, then condense in the first condenser 12 and measure with the first flowmeter 13, and then collect into the first storage tank 14;

(2) After the volatile compounds are completely separated, close the compressor 10, the first vacuum pump 15, the first condenser 12, open the second condenser 17 and the second vacuum pump 20, and set the heating temperature of the temperature control device 3 to 60 ℃-100℃, using the transmembrane vapor pressure difference generated by the second vacuum pump 20 as the driving force, the water vapor passes through the membrane holes, passes through the fourth pressure gauge 16, and then condenses through the second condenser 17 and the second flowmeter 18 in turn. After metering, it is collected in the second storage tank 19;

Permeate side pressure is different to achieve separation:

(1) After the raw material liquid is heated by the temperature control device 3 to 60°C-100°C, the circulating pump 4 transports the raw material liquid to the membrane contactor 8 through the valve 5, the thermometer 6 and the first pressure gauge 7, and the retentate side liquid Circulate back to the raw material tank 1, turn on the compressor 10, the first vacuum pump 15, and the first condenser 12, and use the first vacuum pump 15 to generate a vacuum degree of less than 0.095MPa. 9. After the compressor 10 and the third pressure gauge 11, after being condensed by the first condenser 12 and metered by the first flowmeter 13 in turn, it is collected in the first storage tank 14;

(2) After the volatile compounds are completely separated, close the compressor 10, the first vacuum pump 15, the first condenser 12, open the second condenser 17 and the second vacuum pump 20, and utilize the second vacuum pump 20 to produce a vacuum greater than 0.095MPa degree, the water vapor permeates through the membrane holes, first through the fourth pressure gauge 16, then through the second condenser 17 to condense and the second flowmeter 18 to measure, and then collect in the second storage tank 19;

The membrane contactor 8 uses a hydrophobic hollow fiber membrane or a flat membrane. Organic membranes can be used, such as polytetrafluoroethylene, polyvinylidene fluoride, polyethylene or polypropylene, etc.; inorganic membranes, such as metal oxide membranes, zeolite membranes, etc.; composite membranes, such as polyvinyl alcohol/microsodium cellulose, etc.

The membrane contactor separation method and system for multiple pollutant aqueous solutions proposed by the present invention have the following advantages:

(1) The concentration range of processing raw materials is wide, and the operation mode is flexible. The separation of volatile compounds and water vapor can be achieved by selecting different feed temperatures or permeate side pressures in the two steps according to the specific composition and conditions of the raw material liquid.

(2) The process is easy to control and has good stability. The effective operation of the system can be realized by adjusting the vacuum pump and temperature control device.

(3) The membrane contactor is highly integrated, small in size, and the hydrophobic microporous membrane is cheap.

Description of drawings

Fig. 1 is a schematic diagram of a membrane contactor separation system for multi-component pollutant aqueous solution.

In the figure: 1 raw material tank; 2 stirring device, 3 temperature control device; 4 circulating pump; 5 valve; 6 thermometer; 7 first pressure gauge; 8 membrane contactor; 9 second pressure gauge; 10 compressor; 11 third Pressure gauge; 12 the first condenser; 13 the first flow meter; 14 the first storage tank; 15 the first vacuum pump; 16 the fourth pressure gauge; 17 the second condenser; 18 the second flow meter; 19 the second storage tank; 20 second vacuum pump.

Detailed ways

The specific implementation manner of the present invention will be further described below in conjunction with the accompanying drawings and process solutions.

Example 1

Take the hydrophobic PP hollow fiber membrane to make the membrane contactor 8 . The COD content of a certain chemical wastewater is 38800ppm, the TDS content is 11000ppm, put it into the raw material tank 1, turn on the stirring device 2, set the temperature control device 3 to 50°C, heat the feed liquid to 50°C, open the valve 5, and adjust the circulating pump 4 to 80rpm, after the feed liquid circulates and flows stably in the membrane contactor and the raw material tank, turn on the compressor 10, set the temperature of the first condenser 12 to 0°C, turn on the first vacuum pump 15, and after running for 2 hours, the first flowmeter 13 The indication is reduced to 0, and the compressor 10, the first condenser 12, and the first vacuum pump 15 are turned off; the temperature device 3 is set to 90°C, the feed liquid is heated to 90°C, and the second condenser 17, the second After the vacuum pump 20 runs for 4 hours, the indication of the second flow meter 18 decreases to 0, the feed liquid is circulated back to the raw material tank 1, and all equipment in the device is closed. The test results of the liquid in the first storage tank 14 and the second storage tank 19 show that the first storage tank 14 is close to pure COD, the content of COD in the second storage tank 19 is less than 1000, and the content of TDS is less than 200.

Example 2

Get the hydrophobic PTFE flat membrane to make the membrane contactor 8. The mass fraction of hydrogen chloride in a hydrogen chloride wastewater is 3.65%. Add it to the raw material tank 1, turn on the stirring device 2, set the temperature control device 3 to 90°C, heat the feed liquid to 90°C, open the valve 5, and adjust the circulation pump 4 It is 80rpm, and after the feed liquid circulates and flows in the membrane contactor and the raw material tank, the compressor 10 is turned on, the temperature of the first condenser 12 is set to 0°C, the first vacuum pump 15 is turned on, and its vacuum degree is adjusted to 0.09MPa. After running for 1h, the first flow meter 13 indications are reduced to 0, and the compressor 10, the first condenser 12, and the first vacuum pump 15 are turned off; the second condenser 17, the second vacuum pump 20 are turned on, and the vacuum pump pressure is adjusted to 0.098 MPa, after running for 3 hours, the indication of the second flowmeter 18 is reduced to 0, the feed liquid is circulated back to the raw material tank 1, and all equipment in the device is closed. The test results of the liquid in the first storage tank 14 and the second storage tank 19 show that the first storage tank 14 contains nearly pure hydrogen chloride, and the content of hydrogen chloride in the water in the second storage tank 19 is less than 0.05%.

Claims (3)

1. a kind of membrane contactor separation method for polynary pollutant aqueous solution, piece-rate system used includes that a film contacts Device and two groups of condensing units；One group of condensing unit is used for the volatile compounds in separating feed liquid, and another group of condensing unit is used Carry out the moisture in separating feed liquid, separation is reached by the feeding temperature or osmotic lateral pressure difference of two steps, which is characterized in that step It is rapid as follows：

Feeding temperature difference realizes separation：

(1) agitating device (2) is mounted in the head tank (1) with chuck, and material liquid is heated to 30 through temperature control device (3) After DEG C -55 DEG C, material liquid is delivered to membrane contactor by circulating pump (4) by valve (5), thermometer (6) and first pressure gauge (7) (8) in, retentate side liquid circulation is returned in head tank (1), opens compressor (10), the first vacuum pump (15) and the first condenser (12), it is motive force using the cross-film vapour pressure deficit that the first vacuum pump (15) generates, volatile compounds penetrate fenestra, pass through successively After second pressure gauge (9), compressor (10) and third pressure gauge (11), then successively through the first condenser (12) condensation and it is first-class After gauge (13) metering, it is collected into the first storage tank (14)；

(2) after volatile compounds are kept completely separate, close compressor (10), the first vacuum pump (15), the first condenser (12), The second condenser (17) and the second vacuum pump (20) are opened, the heating temperature of temperature control device (3) is set as 60 DEG C -100 DEG C, profit It is motive force with the cross-film vapour pressure deficit that the second vacuum pump (20) generates, vapor penetrates fenestra, first through the 4th pressure gauge (16), It is collected into the second storage tank (19) after the second condenser (17) condensation and second flowmeter (18) metering successively again；

Osmotic lateral pressure difference realizes separation：

(1) for material liquid after temperature control device (3) is heated to 60 DEG C -100 DEG C, material liquid is passed through valve by circulating pump (4) (5), thermometer (6) and first pressure gauge (7) are delivered in membrane contactor (8), and retentate side liquid circulation is returned in head tank (1), Compressor (10), the first vacuum pump (15), the first condenser (12) are opened, is generated less than using the first vacuum pump (15) The vacuum degree of 0.095MPa, volatile compounds penetrate fenestra, successively through second pressure gauge (9), compressor (10) and third pressure After power table (11), then the first storage tank is collected into after the first condenser (12) condensation and first flowmeter (13) metering successively (14) in；

(2) after volatile compounds are kept completely separate, close compressor (10), the first vacuum pump (15), the first condenser (12), The second condenser (17) and the second vacuum pump (20) are opened, the vacuum more than 0.095MPa is generated using the second vacuum pump (20) Degree, vapor penetrates fenestra, first through the 4th pressure gauge (16), then successively through the second condenser (17) condensation and second flowmeter (18) it after measuring, is collected into the second storage tank (19).

2. membrane contactor separation method according to claim 1 and system, which is characterized in that the membrane contactor (8) The middle film used is hollow-fibre membrane or plate membrane.

3. membrane contactor separation method according to claim 2 and system, which is characterized in that the hollow-fibre membrane or Plate membrane is organic film, inoranic membrane or composite membrane.