CN201276442Y - Brackish water desalination device - Google Patents

Abstract

The utility model discloses a brackish water desalination device, which comprises a raw water tank, a high-pressure pump connected in sequence, a reverse osmosis membrane module device, and a terminal water tank, and also includes a raw water pump, a laminated filter, and a program-controlled ultrafiltration device in sequence. A physical-chemical program-controlled composite coupling pretreatment device connected in sequence. The utility model has the advantage that it adopts the physical-chemical program-controlled composite coupling pretreatment filtration process, which can pretreat raw water of different types and different water qualities, so that it can meet the water inlet requirements of the reverse osmosis membrane module device, thereby improving the efficiency of reverse osmosis desalination. The treated influent water quality prevents the colloidal and microbial fouling of the membrane elements in the reverse osmosis membrane module device, improves the permeation flux per unit area of the reverse osmosis membrane module, and increases the protection of the reverse osmosis membrane elements; at the same time reduces The frequency of chemical cleaning of reverse osmosis membrane elements prolongs the service life of membrane elements, reduces operating costs and improves production efficiency.

Description

A brackish water desalination device

technical field

The utility model belongs to the field of brackish water desalination technology, in particular to a brackish water desalination device that can solve domestic drinking water, especially the purification problems of rural brackish water, high-fluorine water, high-arsenic water and highly polluted water .

Background technique

The desalination of brackish water is actually the desalination of salt water, so that the desalination and desalination of salt water can reach the standard of drinking water. The brackish water (seawater) desalination technology is becoming more and more mature in the world, mainly including distillation, electrodialysis and reverse osmosis: Distillation is the process of heating brackish water (seawater) to boil and evaporate, and then condensing the steam into fresh water , this method is expensive, easy to corrode the structure, and difficult to enlarge. Electrodialysis is a membrane separation technology that uses ion exchange membranes to separate anions and cations in brackish water (sea water) under the action of an electric field, thereby reducing the salt concentration in the fresh water chamber and obtaining fresh water. Because it cannot remove organic matter in the water and bacteria, coupled with the high energy consumption of equipment operation (the energy consumption is proportional to the salinity of feed water), so its application in brackish water desalination projects is limited, so the original electrodialysis device is gradually used in brackish water desalination Replaced by a reverse osmosis unit. Reverse osmosis is a technology that uses a "semi-permeable membrane" with selective permeability to separate salt from brackish water (sea water) to achieve desalination of salt water; reverse osmosis can remove more than 90% of dissolved water from water Compared with other water treatment methods, it has no phase change, normal temperature operation, simple equipment, high efficiency, less land occupation, convenient operation, low energy consumption, and wide application range Wide range, high degree of automation and good water quality. Among the existing desalination methods, the reverse osmosis method is the most economical and energy-saving, and meets the requirements of "clean production". It is a more reasonable and effective method for desalination of brackish water than other methods.

The reverse osmosis desalination method for brackish water in the prior art generally has the following scheme: the raw water is pretreated, that is, the raw water is first intermittently chlorinated, then flocculants and coagulants are added, and then passed through a media filter (such as quartz sand , anthracite or manganese sand and other multi-media filtration), activated carbon adsorber, 3 ~ 10μm precision filter, antiscalant system, and then adjust the pH value and other steps. Then the pretreated raw water is directly sent to the reverse osmosis membrane module device through the high-pressure pump for reverse osmosis water treatment, and the treated water is directly sent into the drinking water tank for supply to users. The disadvantage of this technology is that the effect of the above-mentioned pretreated raw water is not ideal, the pollution index SDI is relatively high, and the turbidity is also high. Sometimes the organic matter adsorbed by activated carbon will become a breeding ground for bacteria, so it cannot meet the requirements of reverse osmosis membrane. The water inlet requirements of the module device, so it is easy to make the membrane elements in the reverse osmosis membrane module device foul very quickly. At this time, in order to maintain the designed water production, the reverse osmosis membrane elements must be chemically cleaned frequently, thereby reducing the service life of the reverse osmosis membrane elements, increasing operating costs, and reducing production efficiency.

Contents of the invention

The technical problem to be solved by the utility model is to provide a method to ensure that the raw water transported to the reverse osmosis membrane module device has a pollution index and turbidity that meet the water inlet requirements of the reverse osmosis membrane module device. A brackish water desalination device that eliminates the need for frequent chemical cleaning of the membrane elements in the reverse osmosis membrane module device and improves the service life of the membrane elements.

The technical scheme adopted by the utility model to solve the above-mentioned technical problems is: a brackish water desalination device, including a raw water tank, a high-pressure pump, a reverse osmosis membrane module device, and a drinking water tank connected in sequence, and is characterized in that it also includes a A physicochemical program-controlled composite coupling pretreatment device connected with the raw water tank and the high-pressure pump.

The physical-chemical program-controlled composite coupling pretreatment device includes a raw water pump, a laminated filter, and a program-controlled ultrafiltration device; the raw water pump, laminated filter, and program-controlled ultrafiltration device are sequentially connected; the raw water pump is connected to the Raw water tank, the program-controlled ultrafiltration device is connected to the high-pressure pump.

An intermediate water tank is connected between the program-controlled ultrafiltration device and the high-pressure pump; a pH adjustment device is connected between the raw water pump and the laminated filter; a bactericide adding device and a flocculant adding device are respectively connected to the raw water tank. device; the intermediate water tank is connected with a reducing agent and scale inhibitor adding device; the reverse osmosis membrane module device is connected with a chemical cleaning device.

Compared with the prior art, the utility model has the advantage that it adopts the physicochemical program-controlled composite coupling pretreatment filtration process, which can pretreat raw water of different types and different water qualities, so that it can meet the water inlet requirements of the reverse osmosis membrane module device , thereby improving the influent water quality of reverse osmosis desalination treatment, preventing colloidal and microbial fouling of the membrane elements in the reverse osmosis membrane module device, improving the permeation flux per unit area of the reverse osmosis membrane module, and increasing the impact on the reverse osmosis membrane Component protection; at the same time, it reduces the frequency of chemical cleaning of reverse osmosis membrane elements, prolongs the service life of membrane elements, reduces operating costs, and improves production efficiency.

The utility model not only has an excellent desalting effect, but also has an excellent defluoridation effect. For brackish water with high salinity and high fluorine content, the desalination rate can reach more than 97%, and the fluorine removal rate can reach more than 98%, and all indicators meet the national drinking water standards.

Description of drawings

Fig. 1 is the structural block diagram of the utility model embodiment.

Detailed ways

The utility model is described in further detail below in conjunction with the accompanying drawings.

As shown in Figure 1, a brackish water desalination device includes a raw water tank 1, a high-pressure pump 4 connected in sequence, a reverse osmosis membrane module device 5, and a drinking water tank 6, and also includes a high-pressure The pump 4 is connected to the physicochemical program-controlled composite coupling pretreatment device 2 .

The physical-chemical program-controlled composite coupling pretreatment device 2 includes a raw water pump 21, a laminated filter 23, and a program-controlled ultrafiltration device 24; the raw water pump 21, the laminated filter 23, and the program-controlled ultrafiltration device 24 are sequentially connected; The raw water pump 21 is connected to the raw water tank 1 , and the program-controlled ultrafiltration device 24 is connected to the high-pressure pump 4 .

The filter elements of the laminated filter 23 are laminated sheets, which have different filter degrees. A series of laminations of the same precision are stacked together and pressed tightly by springs. At this time, the grooves between the laminations intersect to form a deep filter unit with multiple filtering channels. Put this unit into the filter cartridge to form a Laminated filter 23.

The operation and backwashing of the laminated filter 23 are fully-automatically controlled, the operation and management are simple, and the maintenance amount is very small. There is no need to replace the filter element within several years, and the user does not need to purchase and replenish fillers; there are no daily consumables, such as filter elements , filter bags, etc., with low operating costs and low labor intensity for operators. It is a new generation of filter with stronger reliability and higher working efficiency. It can minimize water consumption and reduce system maintenance costs.

Due to its specific mechanical structure, the laminated filter 23 has a good interception effect on suspended solids larger than the filter pore size, and has a certain effect on the turbidity caused by large particle diameter suspended solids. But it has almost no effect on turbidity caused by suspended matter smaller than the cut-off pore size, and has no effect on COD and chroma. Therefore, the laminated filter 23 is more suitable for the ultrafiltration pretreatment process of water bodies with high suspended solids and low COD concentration.

The program-controlled ultrafiltration device 24, as the main equipment for reverse osmosis pretreatment, can improve the water quality of the influent water of the reverse osmosis membrane module device 5, prevent the colloidal pollution and microbial contamination of the membrane modules in the reverse osmosis membrane module device 5, and improve the efficiency of the reverse osmosis membrane element. The permeate flux per unit area is higher, and the recovery rate of the reverse osmosis membrane module device 5 is improved.

The membrane module of the program-controlled ultrafiltration device 24 selects an external pressure type polypropylene hollow fiber ultrafiltration membrane, which is the latest generation of membrane separation materials in the world, compared with other ultrafiltration membranes such as polysulfone and cellulose acetate. , has the advantages of high strength, acid and alkali resistance, bacterial corrosion resistance, good temperature resistance, non-polar surface, strong anti-pollution ability, uniform micropores, and large flux per unit area.

During the working process, there are various pollutants on the surface of the ultrafiltration membrane, so that the performance of the utility model, that is, the water production rate, decreases, and the pressure difference between the inlet and outlet of the ultrafiltration membrane module increases. For this reason, in addition to frequent pulse backwashing of ultrafiltration membrane components, regular chemical cleaning is also required. Generally, the backwash cycle of the program-controlled ultrafiltration device 24 is 2 to 4 hours. Ultrafiltration is a process method that overcomes various disadvantages of the traditional pretreatment process, simplifies the traditional pretreatment process, and makes the physicochemical program-controlled composite coupling pretreatment device 2 more effective. Its advantages are: no coagulant is required, less sludge is discharged, and the pollution of the reverse osmosis membrane element by the coagulant is eliminated at the same time; the effluent water quality is stable and reliable, even if the raw water quality, flow rate and water temperature fluctuate greatly, the pollution index of the ultrafiltration effluent The SDI value is kept below 2.0; the ultrafiltration membrane module is modularized, compact in structure, and occupies a small area; easy to operate and maintain, and low in operating costs; quick to start and stop, and can provide high-quality water supply and feedback soon after startup Osmotic membrane module device 5; the frequency of chemical cleaning of the reverse osmosis membrane module device 5 is reduced, and the service life of the reverse osmosis membrane module is prolonged.

An intermediate water tank 3 is connected between the program-controlled ultrafiltration device 24 and the high-pressure pump 4; a pH adjustment device 22 is connected between the raw water pump 21 and the laminated filter 23; a bactericide is respectively connected to the raw water tank 1 Adding device 11 , a flocculant adding device 12 ; the intermediate water tank 3 is connected to a reducing agent and scale inhibitor adding device 31 ; the reverse osmosis membrane module device 5 is connected to a chemical cleaning device 51 .

The membrane elements in the reverse osmosis membrane module device 5 can be connected in parallel or in series.

The working principle of the utility model is as follows:

When the utility model works, the raw water tank 1 adds an appropriate amount of bactericide to the raw water through the bactericide adding device 11 to sterilize the raw water, and then adds the flocculant basic aluminum chloride PAC through the flocculant adding device 12, and it will interact with the fine particles in the raw water. Colloids, particles and other impurities form flocs, which are beneficial to be filtered out in the laminated filter, reducing the turbidity and pollution index of the effluent; and then adding acid to adjust the pH value of the raw water through the pH value adjustment device 22, which prevents CaCO in the raw water ₃ Precipitation on the reverse osmosis membrane, the raw water pump 21 sends the raw water to the automatic operation laminated filter 23, mainly used to prevent sand particles and turbidity in the water from entering the program-controlled ultrafiltration device 24, and scratching the membrane surface of its membrane components; Finally, it enters the program-controlled ultrafiltration device 24, which can improve the influent water quality of the reverse osmosis membrane module device, prevent colloidal pollution and microbial contamination of the reverse osmosis membrane element, and is equipped with frequent pulse backwashing and chemical cleaning systems for the ultrafiltration device, thereby ensuring program-controlled The stability of the operation performance of the ultrafiltration device 24.

In addition, in the intermediate water tank 3, scale inhibitors are added through the reducing agent and scale inhibitor adding device 31 to prevent the concentrated water side of the reverse osmosis membrane module from scaling and precipitation due to barium and strontium ions; adding reducing agents for Reduce the remaining oxidant in the influent to ensure the safe operation of the system. The chemical cleaning device 51 connected to the reverse osmosis membrane module device 5 regularly backwashes the reverse osmosis membrane module device 5 to ensure its normal operation.

Claims (7)

1. A brackish water desalination device, comprising a raw water tank (1), a high-pressure pump (4), a reverse osmosis membrane module device (5), and a drinking water tank (6) connected in sequence, is characterized in that it also includes a A physical-chemical program-controlled composite coupling pretreatment device (2), the physical-chemical program-controlled composite coupling pretreatment device (2) is connected to the raw water tank (1) and the high-pressure pump (4) respectively. 2. The brackish water desalination device according to claim 1, characterized in that, the physical-chemical program-controlled composite coupling pretreatment device (2) includes a raw water pump (21), a laminated filter (23), a program-controlled ultrafiltration device (24); the raw water pump (21), the laminated filter (23), and the program-controlled ultrafiltration device (24) are sequentially connected; the raw water pump (21) is connected to the raw water tank (1), and the The program-controlled ultrafiltration device (24) is connected to the high-pressure pump (4). 3. The brackish water desalination device according to claim 2, characterized in that an intermediate water tank (3) is connected to the program-controlled ultrafiltration device (24) and the high-pressure pump (4) respectively. 4. The brackish water desalination device according to claim 3, characterized in that a pH adjustment device (22) is connected between the raw water pump (21) and the laminated filter (23). 5. The brackish water desalination device according to any one of claims 1 to 4, characterized in that, the raw water tank (1) is respectively connected to a fungicide adding device (11), a flocculant adding device device (12). 6. The brackish water desalination device according to claim 5, characterized in that the intermediate water tank (3) is connected with a reducing agent and scale inhibitor adding device (31). 7. The brackish water desalination device according to claim 6, characterized in that the reverse osmosis membrane module device (5) is connected to a chemical cleaning device (51).

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