CN103991937B - One utilizes the continuous wastewater treatment equipment of membrane capacitance deionization - Google Patents

Abstract

The invention relates to a continuous wastewater treatment device for deionization using membrane capacitance. The upper and lower ends of a cylindrical shell are coaxially installed with upper and lower cover plates, and the central axis parts of the upper and lower cover plates are connected with the inside of the shell to install water inlet and outlet nozzles. A water collecting plate is installed coaxially on the upper cover plate in the housing, conductive rods are installed in the axial direction at uniform intervals on the outer edge of the housing, and a lower distribution board is coaxially installed in the housing between the water distribution plate and the water collecting plate And the upper distribution board, the upper and lower distribution boards are a pair of metal plates, and the upper current collector, the positive electrode of membrane carbon, the diaphragm, the negative electrode of membrane carbon, and the lower collector are coaxially installed between the two distribution boards. A flow plate is a set of multiple processing module assemblies. The membrane electrode involved in the present invention is made of a carbon electrode and an ion-exchange membrane as a whole. The cathode is sprayed with a cation-exchange coating, and the anode is spray-coated with an anion-exchange coating to prepare a membrane-forming electrode. The thickness of the ion-exchange layer is less than 10 Micron, the resistance is smaller than the direct addition of the ionic membrane, and the capacitance is large.

Description

A continuous wastewater treatment device using membrane capacitance deionization

technical field

The invention belongs to the technical field of environmental protection equipment, and relates to the removal of ions in waste water and the reuse of boiler water, in particular to a continuous waste water treatment device using membrane capacitor deionization.

Background technique

With the rapid development of social economy and the rapid increase of population, the shortage of water resources (industrial and domestic water shortage) is a long-term and trending problem facing the world, and it has become a major bottleneck restricting economic development. Considering the preciousness of water resources, the reuse of sewage, seawater and brackish water desalination are effective ways to solve the shortage of water resources.

Among the currently disclosed deionization technologies, the common desalination methods include ion exchange, electrodialysis, and reverse osmosis. These methods all have many limitations. For example, if the reverse osmosis method is used, the system has high requirements for water pretreatment. , high-pressure pump energy consumption is high, the water yield is low, and the cost of water production is high; the ion exchange method is used, the acid-base regeneration cost is high, the regeneration waste liquid is easy to cause secondary pollution to the environment, and the system operation requirements are high; the electrodialysis method is used , During the operation process, the cathode and anode membranes are easy to scale, thus affecting the water quality of the effluent, shortening the service life of the instrument and high power consumption and water consumption.

In recent years, a promising new desalination technology for water treatment has received widespread attention—capacitive deionization (CDI) desalination technology. Capacitive deionization, also known as electroadsorption desalination, is to form an electric double layer between the electrode and the solution under the action of an electric field. Polar molecules or ions are stored in the electric double layer and removed. When the electrode is saturated, it can be removed by adding A reverse electric field regenerates the electrodes. Compared with the traditional desalination method, electro-adsorption has low energy consumption, low cost, easy regeneration, and no need for chemicals. It is an economical and effective method. However, after the technology has been in the market for several years, new problems have been exposed, which are reflected in the following aspects:

1. The water flow directly washes the carbon electrode, and the carbon particles will continue to fall;

2. When the power supply is reversed for desorption, some of the desorbed ions are adsorbed to the opposite electrode, and the desorption is not complete, resulting in low operating efficiency and low salt removal rate;

3. To meet the water outlet requirements, many electro-adsorption modules are required, which requires a large investment and a large floor area;

4. The treatment efficiency is low, and generally it can only deal with liquids with an ion concentration of 200-2000 mg/L;

5. The recoil concentration changes smoothly, and generally cannot be used for concentration, and the water production rate is not high. To increase the water production rate, you can only increase the module.

In addition, the existing formed ion-exchange membrane covers the surface of the electrode by pressure, which will increase the contact resistance of the electrode and the ion-exchange membrane, and will also increase the thickness of the ion diffusion layer. When the concentration of the solution to be treated is low, The thickness of the ion exchange membrane is relatively too large, so the permeability of ions becomes poor, and the contact resistance of the membrane becomes larger.

Through the search, the following two related published patent documents were found:

1. A high-efficiency energy-saving diaphragm capacitive deionization device (CN101337717), characterized in that: an ion-exchange membrane (2) is added between the separator (1) and the electrode (3), and the upper and lower support plates (6 ) are provided with nozzles (7), and the positions of the upper and lower nozzles are arranged in a staggered manner. Compared with the prior art, the present invention uses dense and porous carbon-based materials as capacitive deionization electrodes, and adds ion exchange membranes to make the device thin and light, optimize the structure, improve the performance of adsorption, and reduce the working time of the electrodes. Apply voltage, thereby greatly reducing the energy consumption of the device and the cost of manufacturing and use, high ion adsorption efficiency, good stability, long life, low power consumption, fast response and reusable.

2. An electrode plate stack structure (CN101624229), the electrode plate stack structure is formed by a plurality of first electrode plates and a plurality of second electrode plates interspersed at intervals, wherein each of the first electrode plates is equipped with a plurality of A first pattern formed by perforation and an O-ring is arranged on the edge of each of the first electrode plates, and a second pattern formed by a plurality of perforations is arranged on each of the second electrode plates, and each of the first electrode plates is provided with a second pattern An O-ring is arranged on the edge of the two electrode plates; and a locking device is arranged at the top and bottom of the electrode plate stack structure to lock the electrode plate stack structure; wherein an uppermost layer of the electrode plate stack structure The electrode plate and a lowermost electrode plate are connected to an electrode of a first polarity, and an intermediate electrode plate of the stacked structure is connected to an electrode of a second polarity, and the first polarity and the second polarity are opposite polarity.

Through the comparison of technical features, although the above two published patent documents are also equipped with ion exchange membranes, their structures and principles are quite different from those of the present application.

Contents of the invention

The present invention overcomes the deficiencies of the prior art and provides a continuous wastewater treatment device using membrane capacitor deionization, which can effectively solve the problems of low desalination efficiency, easy scaling and meeting water discharge requirements in the industrialization process of old capacitor deionization devices There are many electro-adsorption modules, large investment, and large floor space.

The purpose of the present invention is achieved through the following technical solutions:

A continuous wastewater treatment device using membrane capacitor deionization, including a water inlet nozzle, a lower cover plate, a lower gasket, a water distribution plate, a housing, a conductive rod, a treatment module assembly, a water collecting plate, an upper gasket, and an upper cover plate And the water outlet, the lower end of the cylindrical shell is coaxially installed with the lower cover, and the middle axis of the lower cover is connected with the inside of the shell to install the water inlet. The lower cover and the shell are sealed by the lower gasket and fixed by bolts. A water distribution plate is installed coaxially on the lower cover plate in the shell; an upper cover plate is coaxially installed on the upper end of the cylindrical shell, and a water nozzle is installed on the central axis of the upper cover plate connected with the inside of the shell, and the upper cover plate It is sealed with the shell through the upper gasket and fixed with bolts. A water collecting plate is coaxially installed on the upper cover plate in the shell, and conductive rods are installed on the outer edge of the shell at uniform intervals in the axial direction. Between the water distribution plate and the The lower switchboard and the upper switchboard are coaxially installed in the shell between the water collecting plates. The upper and lower switchboards are a pair of metal plates, and 8-12 switchboards are coaxially installed between the two switchboards Group processing module components.

Moreover, the processing module components are all coaxially composed of an upper current collecting plate, a membrane carbon positive electrode, a diaphragm, a membrane carbon negative electrode, and a lower current collecting plate, and are sandwiched horizontally in the distribution boards on both sides layer by layer. The diaphragm is a diaphragm with small holes; the upper and lower current collectors are graphite films, and each pair of film carbon electrodes is connected to the conductive rod through the current collector and the distribution board, and the conductive rod is connected to the power supply .

Moreover, the surfaces of the positive and negative electrodes of the carbon film are sprayed with extremely thin anion and cation films, wherein a cation exchange coating is sprayed on the negative electrode of the carbon film, and an anion exchange coating is sprayed on the positive electrode of the carbon film to prepare a film An electrode having an ion exchange coating less than 10 microns thick.

Advantage and positive effect of the present invention are:

1, the membrane electrode involved in the present invention is that carbon electrode and ionic membrane are made into one, adopts spraying cation exchange coating on cathode, sprays anion exchange coating on anode, prepares membrane electrode, the thickness of its ion exchange layer Less than 10 microns, the resistance is smaller than the direct addition of the ionic membrane, and the capacitance is large.

2. In the process of electroadsorption desalination using the membrane electrode, since there is no repulsion of the same ion, whenever an electron is transferred on the electrode, a salt ion will be adsorbed from the solution, in addition to avoiding the repulsion of the same ion Another advantage is that when desorbing ions, when the electrodes are reversed, the ions will be desorbed more thoroughly, so this also increases the desalination capacity of the electrosorption device during the continuous adsorption and desorption process.

3. The distance between the membrane carbon electrodes of the present invention is only a layer of diaphragm, which is almost zero, and the structure of serpentine or other liquid channels between the electrodes of the old-fashioned device has been changed. One layer spreads over the electrode sheet for adsorption. The biggest advantage of this module is that it is easy to disassemble, and the number of pairs of membrane electrodes can be adjusted at any time according to the needs, and the distance between the electrode sheets is very close, so that the ions remain stable when passing through a large flow rate solution. It has better adsorption capacity.

In addition, the comparison between this patent application and the existing capacitive deionization device and technology:

(1) The existing capacitive adsorption method does not have an ionic membrane, and the water flow directly washes the carbon electrode, and the carbon particles will continue to fall; however, due to the shielding and coating of the ionic membrane in the membrane electrode, the water flow does not directly wash the carbon electrode, but Flowing through between the ion membranes, coupled with our special carbon electrode processing method, long-term use will not cause the carbon electrode to wash out and fall off.

(2) Due to the effect of the ion diaphragm, the ions desorbed from the electrode during reverse charging can only return to the solution or water, and cannot be adsorbed to the opposite electrode, so that the electrode is fully cleaned, and then the next charge and adsorption can be started. The ion removal rate and the operating efficiency of the device are improved.

(3) Due to the selective permeability of the ionic membrane, it can handle solutions with a concentration of tens of thousands of milligrams per liter or more. Because the membrane electrode is made in one piece, the thickness is extremely thin and the resistance is small. In addition, the sandwich-type zero-distance structure can also handle the concentration The solution of less than 10 mg/L changes the current situation that the existing capacitive adsorption method can only deal with liquids with a concentration of 200-2000 mg/L, and expands the scope of application.

(4) The present invention can instantaneously backflush a concentrated solution with a concentration higher than 10 times that of the original solution, which is beneficial to recovery and concentration, can reduce the process of evaporation and concentration by other methods, and reduce energy consumption, while the backflush concentration of the existing capacitive adsorption method changes gently, Generally cannot be used for concentration.

⑸Existing capacitive deionization (CDI) technology causes fouling due to desorption and unexpected bottom measurement. This kind of scaling will reduce the point efficiency of adsorption/desorption during charging/reverse charging, just like adding a layer of thin film resistance, so that the adsorption capacity Decrease, or increase energy consumption; block the channel of water flow, cause the operating pressure to rise, easily damage the seal of the module and cause water leakage. In the present invention, due to the effect of the ion membrane, the carbon electrode is fully cleaned every time, and it is a new electrode for adsorption, which will not form colloids and scaling; at the same time, because the module has good acid and alkali resistance, it can be washed with acid, Eliminate fouling phenomenon.

Description of drawings

Fig. 1 is the plane assembly drawing of the present invention

Fig. 2 is a schematic diagram of an explosion structure of the present invention;

Fig. 3 is a comparative diagram of the application experiment of the membrane capacitive deionization device of the present invention and the capacitive deionization device.

Detailed ways

The embodiments of the present invention will be described in further detail below in conjunction with the accompanying drawings; the present embodiments are descriptive, not restrictive, and cannot thereby limit the protection scope of the present invention.

A continuous wastewater treatment device utilizing membrane capacitor deionization, comprising a water inlet 17, a lower cover plate 16, a lower gasket 15, a water distribution plate 14, a housing 6, a conductive rod 2, a treatment module assembly, a water collecting plate 5, The upper gasket 4, the upper cover plate 3 and the water outlet 1, the lower end of the cylindrical shell is coaxially installed with the lower cover plate, and the water inlet nozzle is connected to the central axis of the lower cover plate and the shell, and the lower cover plate and the shell The lower gasket is used for sealing and the bolts are used for fixing. A water distribution plate is coaxially installed on the lower cover plate in the shell; The water nozzle is connected to the housing, the upper cover plate and the housing are sealed by the upper gasket, and the bolts are fixed. The water collecting plate is coaxially installed on the upper cover plate in the housing, and the outer edge of the housing is evenly spaced in the axial direction. Conductive rods are installed, and the lower switchboard 13 and the upper switchboard 7 are coaxially installed in the shell between the water distribution plate and the water collection plate. The upper and lower switchboards are a pair of metal plates. Multiple groups of processing module assemblies are installed coaxially between the distribution boards.

Each processing module assembly is composed of an upper current collector plate 8, a membrane carbon positive electrode 9, a diaphragm 10, a membrane carbon negative electrode 11, and a lower current collector plate 12. The five components of the processing module assembly are horizontal Clamps inside the power distribution board on both sides. The diaphragm is a diaphragm with small holes to prevent the short circuit of the module; the distance between the carbon positive and negative electrodes of the film is only a diaphragm, which is almost zero, which changes the serpentine shape between the electrodes of the old-fashioned device. Or the structure of other forms of liquid channels; the upper and lower collector plates are graphite films, and each pair of film carbon electrodes is connected to the conductive rod through the current collector plate and the distribution board, and the conductive rod is connected to the power supply. Membrane carbon electrodes are connected in series, which can greatly reduce the working current and simplify the power supply system.

The surface of the positive and negative electrodes of the carbon film is sprayed with an extremely thin anion and cation film. The specific spraying method is:

Spray a cation exchange coating on the carbon film negative electrode, and spray an anion exchange coating on the carbon film positive electrode to prepare a film-forming electrode. The thickness of the ion exchange layer is less than 10 microns, which is smaller than the resistance of the ionic film directly. The large capacity makes the deionization rate and desalination efficiency significantly improved, the electrode is not suitable for scaling, and the concentrated water is conducive to concentration and reuse. The technology has low operating cost and wide application range. The ion removal efficiency is increased by more than 50% compared with the existing capacitive deionization technology for wastewater with high conductivity or low conductivity, and is suitable for continuous treatment of large-flow wastewater. The addition of the ionic membrane does not increase the resistance of the entire adsorption module. The voltage of each pair of electrodes is 0.5-1.2V. The entire continuous device realizes low-current operation, and the operating cost per ton of water is lower than that of the existing capacitive deionization device.

The working principle of the present invention is:

The wastewater to be treated enters the device through the water inlet, and is evenly distributed around the treatment module assembly through the water distribution plate. The peripheral water inlet is adopted, and the treated wastewater is absorbed layer by layer over the membrane carbon electrode sheet. The treatment module assembly The biggest advantage is that it is easy to disassemble, and the logarithm of the membrane carbon electrodes can be adjusted at any time according to the needs, and the distance between the membrane carbon electrodes is very close, so that it still has a good adsorption capacity for ions when passing through a large flow rate solution. The adsorbed water flows out from the center, and flows out from the water outlet through the water collecting plate to achieve the purpose of deionization; the adsorption-desorption replacement of the device operation is completed by short-circuiting and reverse-connection of the power supply, and realized by switching the reverse pole through the solenoid valve.

Taking the treatment of the same ion-containing wastewater as an example, the wastewater enters the membrane capacitive deionization continuous treatment device and the existing capacitive deionization device through a peristaltic pump through the water inlet pipe respectively. The main difference between the two devices is the membrane carbon electrode, and the other is the For carbon electrodes, all other process conditions are the same, and the continuous inflow and outflow water electrosorption test is carried out. The instantaneous conductivity was monitored online until the electrosorption equilibrium. Rinse with raw water during regeneration, desorb the pole, and collect concentrated wastewater. The experimental results show that the desalination efficiency of the membrane capacitor device (MCDI) is nearly 50% higher than that of the existing capacitor device (CDI). With capacitive devices (CDI), the adsorption capacity is decreasing.

The comparison and analysis of the desalination experimental data of the membrane carbon electrode with membrane and without membrane is shown in the table below:

Claims (2)

1. one kind utilizes the continuous wastewater treatment equipment of membrane capacitance deionization, it is characterized in that: comprise water inlet tap, lower cover, lower gasket, water distribution board, housing, conducting rod, processing module assembly, water collection sheet, Upper gasket, upper cover plate and faucet, lower cover is coaxially installed in columnar housing lower end, water nozzle is installed into being communicated with in housing at the axis position of lower cover, lower cover and housing are undertaken sealing by lower gasket, bolt is fixedly mounted with, and the lower cover in housing is coaxially installed with water distribution board, cover plate is coaxially installed in cylindrical shell upper end, faucet is installed at the axis position of upper cover plate with being communicated with in housing, upper cover plate and housing are sealed by Upper gasket, bolt is fixedly mounted with, upper cover plate in housing is coaxially installed with water collection sheet, conducting rod is axially installed with at the uniform interval of housing outer rim, be coaxially installed with in housing between water distribution board and water collection sheet lower switchboard and on switchboard, on, lower switchboard is pair of metal plate, collector plate is coaxially installed with between these two switchboards, film carbon positive electrode, barrier film, film carbon negative potential, lower header plate is many groups processing module assembly of a group,

Very thin zwitterion film is all coated with on the surface of carbon film positive and negative electrode, wherein, carbon film negative potential sprays cationic exchange coating, carbon film positive electrode sprays anionresin coating, be prepared into membrane electrode, the thickness of its ion-exchange coating is less than 10 microns.

2. according to claim 1ly utilize the continuous wastewater treatment equipment of membrane capacitance deionization, it is characterized in that: described processing module assembly is coaxially formed successively by upper collector plate, film carbon positive electrode, barrier film, film carbon negative potential, lower header plate, and in layer level is clipped in the switchboard of both sides; Described barrier film is the foraminate barrier film of one deck band; Described upper and lower collector plate is graphite film, and often pair of film carbon dioxide process carbon electrode is connected with conducting rod by collector plate, switchboard, and conducting rod is connected with power supply.