CN108862489B

CN108862489B - Continuous electrode spacing adjusting type desalting technology for electric adsorption-regeneration and reaction module

Info

Publication number: CN108862489B
Application number: CN201810723530.7A
Authority: CN
Inventors: 王辉; 唐晗昱; 卞兆勇
Original assignee: Beijing Forestry University
Current assignee: Beijing Forestry University
Priority date: 2018-07-04
Filing date: 2018-07-04
Publication date: 2021-07-16
Anticipated expiration: 2038-07-04
Also published as: CN108862489A

Abstract

The invention discloses a continuous electrode spacing adjusting type desalting technology for electric adsorption-regeneration and a reaction module. The reactor comprises a continuous electrode spacing adjustment type desalting reactor box body 1, a raw water tank 2, a purified water tank 3, a final concentrated water tank 4, a power supply 5, a water pump 6 and conductivity meters 7 and 8. The method is used for treating the saline wastewater mainly comprising the waste leachate external drainage, the salt rejection rate can reach 42.6 percent at most, and Cl is contained^‑The removal rate is 73.3 percent, the desalination speed is 90 mg/(L.h), the electrode regeneration rate is 97.3 percent, and the water yield is 91.7 percent. The continuous electro-adsorption-regeneration method adopting the movable slot control and continuously adjusting the electrode spacing has the characteristics of simple operation, stable current density, high desalination rate, high desalination efficiency, high electrode regeneration rate, no scaling phenomenon, high water production rate and long electrode service life, realizes the desalination and regeneration of low-salt industrial wastewater, and has wide prospect in the field of environmental protection and salt-containing wastewater treatment.

Description

Continuous electrode spacing adjusting type desalting technology for electric adsorption-regeneration and reaction module

Technical Field

The invention belongs to the field of environmental protection salt-containing wastewater treatment, and particularly relates to a technology and a reaction module for electro-adsorption-regeneration desalination, which can continuously adjust the electrode spacing, and are mainly applied to low-salt-containing industrial wastewater which cannot reach the regeneration and reuse standard.

Background

The shortage of fresh water resources is an urgent global problem, and the cyclic regeneration of industrial wastewater is urgent at present. The conductivity of the low-salt industrial wastewater represented by the landfill leachate external drainage is usually 1000-4000 mu S/cm, and the wastewater cannot reach the standard for recycling due to the difficulty in further reducing the salt content. The novel method for treating the salt-containing wastewater, namely the electro-adsorption desalting technology developed in recent years has the advantages of no secondary pollution, low requirement on raw water, simplicity and convenience in operation and maintenance, low operation cost and the like. The principle of the method is that voltage or current is applied between electrodes, charged particles in water migrate to the electrodes with opposite charges respectively when raw water flows between the positive electrode and the negative electrode, and are adsorbed by the electrodes and stored in double electrode layers, so that separation from water is realized, and desalted water is obtained.

For industrial low-salt wastewater, because the initial conductivity is not high and the initial conductivity still drops in the constant-voltage electro-adsorption process, the current density between the water flow, the electrode and the loop formed by the power supply also drops continuously, and the current density quickly reaches the adsorption platform because the current density is too small. In addition, ions desorbed in the electrode regeneration stage are secondarily adsorbed on the opposite electrode plate, so that the electrode regeneration rate is low, and the problem which is difficult to solve in the process of electro-adsorption-regeneration desalination is solved, and partial electro-adsorption desalination devices such as Chinese patent CN107935132A written by Wufuping and the like and CN104817143A written by Tangxin and the like adopt anion-cation exchange membranes to prevent secondary adsorption in the regeneration stage, but the economic cost is increased, and the water flow resistance is increased to a certain extent.

In summary, the electro-adsorption desalination has a very wide application prospect, but the traditional electro-adsorption desalination technology is limited by the conditions of fixed electrode spacing, voltage and the like, has the problems of fast reaching an adsorption platform, low electrode regeneration rate and the like, and needs to be optimized and improved on the basis of the prior art.

Disclosure of Invention

Aiming at the defects existing in the technical background, the invention provides a continuous electrode spacing adjustment type desalting technology and equipment which have the advantages of higher desalting rate, high regeneration rate and simple manufacture and operation, and the technology and the equipment can be used for carrying out continuous adsorption-regeneration reaction on low-salt industrial wastewater represented by landfill leachate external drainage, and the obtained desalted effluent can be subjected to industrial regeneration and reuse.

The continuous electrode spacing adjusting type desalination reaction module provided by the invention comprises a continuous electrode spacing adjusting type electro-adsorption desalination device box body 1, a raw water tank 2, a purified water tank 3, a final concentrated water tank 4, a power supply 5, a water pump 6 and conductivity meters 7 and 8 (the operation schematic diagram is shown in figure 3). The method is characterized by comprising the following steps:

1) the box body is provided with a raw water inlet, a top purified water outlet and a bottom concentrated water outlet, the water inlet and the water outlet are respectively provided with a two-way valve or a three-way valve, and the valves control the flow direction of the outlet water in different adsorption-regeneration stages and separate the outlet water with different salt concentrations.

2) And a plurality of sawtooth grooves are arranged on two sides of the box body in parallel in a direction perpendicular to the water inlet, and each sawtooth groove is 1-20mm in width and used for fixing the movable slot and adjusting the electrode spacing.

3) The box body is internally provided with a plurality of detachable movable slots, the front sides of the movable slots are provided with windows, the back sides of the windows are completely sealed, the upper parts of the windows are provided with sockets, and the electro-adsorption polar plates are fixed by inserting the sockets into the movable slots.

4) And one sides of all slot sockets connected with the negative electrode of the power supply in the movable slots are provided with protruding handles with the same length, all the handles are connected at equal intervals, and the outer sides of the handles are provided with a pull rod. The pull rod can push or pull all the slots connected with the negative electrode of the power supply to move in the direction vertical to the water inlet, so that the distance between every two pairs of electrodes is changed.

5) Continuously performing 4 stages of power failure pre-discharging, electrification adsorption, short-circuit standing and reversed electrode regeneration in an operation period, wherein the raw water inlet continuously feeds water in the operation period; water does not flow out in the power failure pre-drainage stage, water flows out from the purified water outlet in the power-on adsorption stage, and the effluent enters the purified water tank; and in the short-circuit standing-reversed pole regeneration stage, the concentrated water outlet discharges water, the discharged water enters the raw water tank for the next operation period, and the discharged water enters the final concentrated water tank after every 4 operation periods. The flow direction of the water inlet and the water outlet corresponding to all the stages is controlled by the valve.

6) And in the operation period, the power failure pre-arrangement stage and the short circuit standing stage are not electrified, the electrodes adjacent to the electrified adsorption stage are respectively connected with the positive electrode and the negative electrode of the power supply, the short circuit standing stage is used for short-circuiting the positive electrode and the negative electrode of the power supply, and the reversed electrode regeneration stage is used for reversely connecting the positive electrode and the negative electrode of the power supply.

7) In the power-on adsorption stage in the operation period, the pull rod controls all slots connected with the negative electrode of the power supply to move one-grid sawtooth slot distance towards the slots connected with the positive electrode of the power supply every 10-15 min; and in the pole-reversing regeneration stage in the operation period, the pull rod controls all the slots connected with the negative pole of the power supply to move for a grid sawtooth slot distance in the direction opposite to the slots connected with the positive pole of the power supply every 5-10 min.

Compared with the prior art, the invention provides an electro-adsorption desalination technology of continuous electrode distance adjustment type electro-adsorption-regeneration, and an electro-adsorption desalination module taking the technology as a main body:

1) the electrode spacing is reduced in real time in the electrifying adsorption stage, the mass transfer distance of ions between the polar plates is reduced under the conditions of constant pressure and reduced raw water conductivity, the stable high current density is maintained, and the stable high desalination rate is ensured;

2) the electrode distance is instantly increased in the reversed electrode regeneration stage, the mass transfer distance of ions between the polar plates is increased, the secondary adsorption generated in the electrode regeneration process is reduced, and the electrode regeneration rate is improved.

Drawings

FIG. 1 is a schematic view of the assembly of a movable slot and electrodes in an electro-adsorption desalination device.

Fig. 2 is a schematic diagram of the control of the pull rod of the movable slot connected to the negative pole of the power supply.

FIG. 3 is a schematic diagram of the operation of an electro-adsorption desalination reaction module.

Detailed Description

The invention is further described below with reference to fig. 1 and 2. The experimental procedures used in the following examples are all conventional procedures unless otherwise specified. Materials, reagents and the like used in the following examples are commercially available unless otherwise specified.

Example 1 desalination apparatus

The desalination reactor comprises an electro-adsorption desalination device box body 1, a raw water tank 2, a purified water tank 3, a final concentrated water tank 4, a power supply 5, a water pump 6, a conductivity meter 7 and a conductivity meter 8:

wherein, the power supply 5 is connected with the electro-adsorption desalination device box body 1 through a lead to form a loop. The power supply 5 is a direct current power supply with adjustable voltage within the range of 0-1.5V. The water pump 6 is a peristaltic pump with the water inflow flow rate adjustable from 0mL/min to 40 mL/min. The

conductivity meters

7 and 8 are the same conductivity meter with the measuring range of 0-5000 mu S/cm. The box body of the electro-adsorption desalination device comprises 6 pairs of electrode plates, and the electrode plates are flat-plate electrodes with anodes and cathodes oppositely arranged and form a baffling channel; the electrode plate is made of a material including carbon felt and a metal of one of aluminum alloy and titanium alloy.

Example 2 electro-adsorption-regeneration

The electro-adsorption desalination device case 1 of example 1 was connected to the power supply 5 via a wire and the power supply was turned on during the electro-adsorption step, and the conductivity was 3200 + -100. mu.S/cm, Cl^-The effluent water of the landfill leachate with the concentration of 560 +/-20 mu S/cm is desalted, and the adsorption desalting conditions are shown in Table 1.

TABLE 1 electro-adsorption-regeneration treatment conditions

After completion of desalting, the desalting rate was 42.6%, Cl^-The removal rate was 66.7%, Ca²⁺The removal rate is 80.2 percent, and Mg²⁺The removal rate is 73.3 percent, the desalting speed is 90 mg/(L.h), and the current density is stabilized at 2.5-3.0 mA/cm in the desalting process². After the electrode regeneration is completed, the electrode regeneration rate is 97.3%, and the water yield is 91.7% after 4 operation cycles. After multiple operations, the electrode plate has no scaling and debris falling phenomena, and the service life of the electrode is long.

The implementation result shows that: the continuous electrode spacing adjusting type desalting technology and the electric adsorption-regeneration reaction module disclosed by the invention provide stable current density in an adsorption stage, and have high desalting rate and desalting efficiency; the regeneration rate of the electrode is high in the regeneration stage, and the scaling phenomenon is avoided; simple operation, high water yield and long electrode service life in the multiple continuous adsorption-regeneration process, and has good prospect in the aspects of treating low-salt industrial wastewater and regenerating and recycling.

The above-described embodiments should be construed broadly within the scope as defined in the appended claims, and therefore all changes that fall within the meets and bounds of the claims, or equivalences of such meets and bounds are therefore intended to be embraced by the claims. The above description is not intended to limit the present invention, but rather, the present invention is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention.

Claims

1. A continuous electrode spacing adjusting type desalting device for electric adsorption-regeneration comprises a continuous electrode spacing adjusting type desalting device box body, a raw water tank, a purified water tank, a final concentrated water tank, a power supply and a water pump, wherein the box body is provided with a water inlet and two water outlets, 3-12 pairs of electrodes can be accommodated in the box body, the electrodes are arranged in parallel, and the adjacent electrodes are respectively connected with the positive electrode and the negative electrode of the power supply; a plurality of sawtooth grooves are arranged on two sides of the box body of the electro-adsorption desalting device in parallel in a direction perpendicular to the water inlet, and each sawtooth groove is 1-20mm in width and used for fixing a movable slot and adjusting the electrode spacing; a plurality of detachable movable slots are arranged in the box body of the electro-adsorption desalting device, windows are arranged on the front sides of the movable slots, the back sides of the windows are completely closed, sockets are arranged on the upper parts of the windows, and electro-adsorption electrode plates are inserted into the movable slots through the sockets and fixed; one sides of all slot sockets connected with the negative electrode of the power supply in the movable slots are provided with protruding handles with the same length, all the handles are connected at equal intervals, and the outer sides of the handles are provided with pull rods; the box body of the electro-adsorption desalting device continuously performs four stages of power failure pre-discharge, power-on adsorption, short circuit standing and reversed electrode regeneration in an operation cycle, wherein in the power-on adsorption stage in the operation cycle, the pull rod controls all slots connected with the negative electrode of a power supply to move one grid of sawtooth groove distance in the direction of the slots connected with the positive electrode of the power supply every 10-15 min, and in the reversed electrode regeneration stage in the operation cycle, the pull rod controls all slots connected with the negative electrode of the power supply to move one grid of sawtooth groove distance in the direction opposite to the direction of the slots connected with the positive electrode of the power supply every 5-10 min.

2. The continuous conditioning electrode spacing desalination plant for electro-adsorption-regeneration as claimed in claim 1, wherein: the water inlet is connected with the water pump, a two-way valve is arranged at the higher position of the water outlet and connected with the water purifying water tank, a three-way valve is arranged at the lower position of the water outlet and connected with the raw water tank and the final concentrated water tank, the water inlet is always closed by the water stop valve in the operation stage, and the water purifying water outlet and the concentrated water outlet are alternately closed by the electro-adsorption desalination device when the box body is in the adsorption stage and the desorption stage.

3. The continuous conditioning electrode spacing desalination plant for electro-adsorption-regeneration as claimed in claim 1, wherein: in the operation period, the water inlet continuously feeds water, water does not flow out in the power-off pre-discharge stage, water flows out from the purified water outlet in the power-on adsorption stage, and the discharged water enters the purified water tank; and in the short-circuit standing-electrode inverting regeneration stage, the concentrated water outlet is discharged, the discharged water enters the raw water tank for the next operation period, and the discharged water enters the final concentrated water tank in the 4 th electrode inverting regeneration stage of each 4 operation periods.

4. The continuous conditioning electrode spacing desalination plant for electro-adsorption-regeneration as claimed in claim 1, wherein: and in the operation period, the power failure pre-arrangement stage and the short circuit standing stage are not electrified, the electrodes adjacent to the electrified adsorption stage are respectively connected with the positive electrode and the negative electrode of the power supply, the short circuit standing stage is used for short-circuiting the positive electrode and the negative electrode of the power supply, and the reversed electrode regeneration stage is used for reversely connecting the positive electrode and the negative electrode of the power supply.