CN110872162A - Moderate desalting device and process - Google Patents
Moderate desalting device and process Download PDFInfo
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- CN110872162A CN110872162A CN201811026754.9A CN201811026754A CN110872162A CN 110872162 A CN110872162 A CN 110872162A CN 201811026754 A CN201811026754 A CN 201811026754A CN 110872162 A CN110872162 A CN 110872162A
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F9/00—Multistage treatment of water, waste water or sewage
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/44—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis
- C02F1/442—Treatment of water, waste water, or sewage by dialysis, osmosis or reverse osmosis by nanofiltration
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/46—Treatment of water, waste water, or sewage by electrochemical methods
- C02F1/469—Treatment of water, waste water, or sewage by electrochemical methods by electrochemical separation, e.g. by electro-osmosis, electrodialysis, electrophoresis
- C02F1/4691—Capacitive deionisation
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- C—CHEMISTRY; METALLURGY
- C02—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F—TREATMENT OF WATER, WASTE WATER, SEWAGE, OR SLUDGE
- C02F1/00—Treatment of water, waste water, or sewage
- C02F1/66—Treatment of water, waste water, or sewage by neutralisation; pH adjustment
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A20/00—Water conservation; Efficient water supply; Efficient water use
- Y02A20/124—Water desalination
- Y02A20/131—Reverse-osmosis
Abstract
A moderate desalting device and a process belong to the technical field of water treatment. The method is characterized in that: the water inlet tank (2) and the middle water tank (4) are respectively connected with the electro-adsorption component (3) through a pipeline provided with a pipeline lift pump; the concentrated water outlet of the electric adsorption component (3) is connected with the nanofiltration component (6) through a pipeline provided with a pipeline lift pump, and the concentrated water port of the nanofiltration component (6) is connected with a concentrated water tank (7). After the raw water enters the water inlet tank (2) for buffering, the raw water is pumped into the electro-adsorption component (3) by a pipeline lift pump for regeneration treatment, and the produced water treated by the electro-adsorption component (3) is sent to the produced water tank (5) for standby; the water in the water production tank (5) is mixed with raw water and then is supplied to the outside; and the concentrated water alkali liquor generated by the nanofiltration component (6) is regulated and then discharged after reaching the standard. The invention has short process flow and simple control, saves the investment and the operation cost of the part, does not add scale inhibitor when the nanofiltration component operates, and does not introduce other pollutants except acid and alkali in the process.
Description
Technical Field
A moderate desalting device and a process belong to the technical field of water treatment.
Background
With the aim of optimizing and utilizing water resources, many enterprises spontaneously or compelled to policy pressure adopt various fresh water sources, reclaimed water, reuse water and the like around the enterprises to replace the original inlet water for production activities so as to reduce the water taking and draining indexes of products per ton. The fluctuation of production devices is often caused by different water quality after the original water is replaced, for example, yellow river water is adopted by a certain chemical industry enterprise to replace local underground water, and as a result, the water production capacity of a desalting device of the enterprise is insufficient, so that the water supply quantity is insufficient, and the production is influenced. At this time, the new water source needs to be subjected to desalting treatment, and the water yield is improved as much as possible during desalting. The desalination process comprises electro-adsorption, reverse osmosis, electrodialysis, nanofiltration and the like, and the desalination process which is applied more at present comprises the electro-adsorption process and the reverse osmosis process.
Wherein the electro-adsorption desalting process is a moderate desalting process, and the reverse osmosis process is a deep desalting process. In order to achieve the purpose of moderate desalting, the water can be directly produced by adopting an electro-adsorption process, or the inlet water and the produced water of a reverse osmosis process are mixed. Generally, water contains hardness and alkalinity, and during desalting, ions are concentrated to cause scaling phenomenon, so that stable operation of a desalting process is influenced. Meanwhile, the concentrated water is generally high-calcium high-salt sewage, the total nitrogen of the concentrated water exceeds the standard due to the concentration of nitrate radicals, and the alkalinity generated in the denitrification process of removing the total nitrogen from the concentrated water reacts with calcium ions to generate precipitates, so that the difficulty of standard treatment and discharge of the concentrated water is increased.
When the electro-adsorption desalination process is adopted, systematic acid addition is needed to prevent scaling. The process has the advantages of adjustable water quality of produced water and high water production rate, generally 85-95%. The method has the disadvantages that in high water yield, in order to ensure the effect of preventing the concentrated ions from scaling in the process of electro-adsorption regeneration, the acidity of the regenerated water is generally controlled to be stronger, so that the produced water and the concentrated water are acidic, the produced water needs to be supplied for external use after neutralization, and the concentrated water needs to be treated and discharged after neutralization.
When the reverse osmosis process is adopted, alkali precipitation pretreatment and ultrafiltration pretreatment are required to generate the alkali residue which is difficult to treat. Meanwhile, the water yield of the reverse osmosis process is generally 70-85%, even if the water inflow and the water production are in a ratio of 1: 1, the water yield is only 82.4-91.9 percent. After the process is determined, the quality of the produced water is basically fixed. And in the reverse osmosis process, scale inhibitor is usually added to relieve the pollution blockage on the membrane surface and ensure the water yield. Therefore, the problems that the organic matters in the concentrated water do not reach the standard and are difficult to treat exist.
Nanofiltration is also a moderate desalination process, which can separate monovalent ions and high valence ions, in addition to ion separation by pore size. Therefore, the nanofiltration is often used for removing hardness during the desalting application, and a scale inhibitor is required to be added in the operation process to relieve the pollution and blockage on the membrane surface and ensure the water yield. Therefore, the problem that the organic matters in the concentrated water do not reach the standard and are difficult to treat also exists.
Chinese patent CN 102616962 discloses a method for deeply grading industrial wastewater, which comprises the following steps: 1) preliminary hardness reduction, precipitation and neutralization, 2) filtration, 3) moderate desalting by electro-adsorption, and 4) deep desalting by reverse osmosis. The problem of reverse osmosis membrane easy pollution, reverse osmosis dense water can not reach discharge and the operation unstable has been solved to this patent. However, the invention relates to the problem that the hardness is reduced by adding alkali precipitation, so that alkali residue is generated, and when the total nitrogen in the concentrated water exceeds the standard, the invention has no counter measures.
Chinese patent CN102603040 discloses an electro-adsorption desalting water treatment method, which is characterized in that before the discharging and standing process, under the condition of continuing to supply water and electrify, industrial hydrochloric acid is injected into an electro-adsorption module, and the water after hydrochloric acid injection is controlled to just fill the system of the electro-adsorption module without being discharged out of the system; controlling the pH value range of the electric adsorption module system to be 2.0-6.0; the produced water enters the water producing tank from normal state and is switched to the middle water tank; and after the electro-adsorption module system is filled with hydrochloric acid, stopping water supply, cutting off a power supply, and entering a discharging, standing and regenerating process. The invention has simple process steps, excellent electrode regeneration effect and no scaling of the electric adsorption module. However, in practical application, the method finds that when high water yield is required, particularly the water yield is higher than 90%, the pH value range of an electric adsorption module system is controlled between 2.0-6.0, the regeneration requirement cannot be met, the acid addition amount needs to be increased further, the produced water and the concentrated water are acidic, and the pH value requirement of utilization or discharge can be met after alkali is added for neutralization. Meanwhile, when the total nitrogen in the concentrated water exceeds the standard, no countermeasure is provided.
In summary, the following technical problems exist in the operation process of the current moderate desalination process:
1. the reverse osmosis technology is used for desalting, so that the problems of low alkali residue generation, substandard total nitrogen of concentrated water and low water yield exist.
2. When the electro-adsorption process is used for desalting, the problem that the total nitrogen of concentrated water may not reach the standard due to excessive acid addition exists when the water yield is high.
3. When the hardness of calcium in the concentrated water is higher, the treatment difficulty of the total nitrogen of the concentrated water reaching the standard is large.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: overcomes the defects of the prior art, provides a moderate desalting device and a moderate desalting process which not only ensure the quality of produced water, but also have high water yield, save electricity, absorb, remove salt and add acid, and ensure that the total nitrogen of concentrated water does not exceed the standard.
The technical scheme adopted by the invention for solving the technical problems is as follows: the moderate desalting device is characterized in that: the device comprises a water inlet tank, a middle water tank, a water production tank, a concentrated water tank, an electric adsorption component and a nanofiltration component, wherein the water inlet tank is connected with a raw water pipeline, the raw water pipeline is also connected with the water production tank, the water production tank is connected with an alkali liquor feeding system, and the middle water tank is connected with an acid liquor feeding system and a water production external supply system; the water inlet tank and the middle water tank are respectively connected with the electric adsorption component through a pipeline provided with a pipeline lift pump, and a return pipeline is also connected between the electric adsorption component and the middle water tank; the concentrated water outlet of the electric adsorption component is connected with the nanofiltration component through a pipeline provided with a pipeline lifting pump, the water outlet of the nanofiltration component is connected with the water inlet tank, the concentrated water outlet of the nanofiltration component is connected with a concentrated water tank, and the concentrated water tank is provided with an alkali liquor pipeline and a concentrated water discharge pipeline.
According to the invention, through reasonable configuration of the electro-adsorption desalting component and the nanofiltration desalting component, concentrated water of the electro-adsorption component is introduced into the nanofiltration component, no scale inhibitor needs to be added during nanofiltration operation, hydrogen ions and nitrate ions which penetrate through the nanofiltration component return to the electro-adsorption component along with nanofiltration produced water, and the concentrated water of the nanofiltration component is discharged as concentrated water. The invention is suitable for water quality, and is particularly suitable for upgrading and utilizing high-quality water sources.
Preferably, the water inlet tank, the intermediate water tank, the product water tank and the concentrated water tank are made of acid and alkali resistant materials or lined with acid and alkali resistant protective layers.
Preferably, each pipeline lift pump is an acid and alkali corrosion resistant pump with acid resistance and a pH value of 0.5-3.0.
The water inlet tank, the intermediate water tank, the production water tank and the concentrated water tank of the process have the functions of storing and transferring water, so that the tank body and the matched pipeline lift pump need to be resistant to acid and alkali corrosion, and the normal production operation of the process can be ensured.
Preferably, the nanofiltration component comprises a nanofiltration membrane, a pipeline valve and an automatic control system of the nanofiltration membrane, and the aperture of the nanofiltration membrane is 100-1000D. The aperture of the nanofiltration membrane of the preferable nanofiltration component can more fully meet the process requirement of the invention, and proper desalination can be fully realized under the condition of no scale inhibitor.
Preferably, the aperture of the nanofiltration membrane is 150-500D. The pore diameter of the nanofiltration membrane can achieve better desalting effect.
Preferably, the electric adsorption component comprises an electric adsorption module, an interface pipeline valve of the electric adsorption module, and an automatic control system. The stable membrane pair voltage of the electric adsorption module is controlled by an automatic control system, so that the electric adsorption effect is ensured.
The moderate desalting process of the device is characterized in that: after 60% -95% of raw water enters the water inlet tank for buffering, pumping the raw water into the electric adsorption component by a pipeline lifting pump for regeneration treatment, controlling the electric adsorption module membrane of the electric adsorption component to have a voltage of 0.5-2.0V, and conveying the produced water treated by the electric adsorption component to the water production tank for later use;
the regeneration treatment in the electric adsorption component comprises two stages: in the first stage, the water in the middle water tank is pumped into the electric adsorption component, and the effluent of the electric adsorption component is sent to the nanofiltration component to be treated as electric adsorption concentrated water; in the second stage of regeneration, a water pump in the water inlet tank is used for pumping water into the electric adsorption component, at the moment, the outlet water of the electric adsorption component is sent to the reclaimed water tank, and acid is added into the reclaimed water tank until the pH value is 0.5-3.0, so that the regeneration is prepared for the next first stage of regeneration; the electric adsorption concentrated water regenerated in the first stage of the electric adsorption component and sent to the nanofiltration component is filtered by nanofiltration, and then nanofiltration produced water mainly containing hydrogen chloride, sodium nitrate and sodium chloride returns to the water inlet tank;
mixing water in the water production tank with raw water, adjusting the pH value with alkali liquor, and supplying the water to the outside; and (4) conveying the concentrated water generated by the nanofiltration component to a concentrated water tank, and adjusting the pH value of the concentrated water tank water by using alkali liquor to reach the standard and then discharging.
According to the process, the electro-adsorption desalting component and the nanofiltration desalting component are reasonably configured, concentrated water of the electro-adsorption component is introduced into the nanofiltration component, a scale inhibitor is not required to be added during nanofiltration operation, hydrogen ions and nitrate ions which penetrate through the nanofiltration component return to the electro-adsorption component along with nanofiltration produced water, and the concentrated water of the nanofiltration component is discharged as concentrated water. The invention is suitable for water quality, and is particularly suitable for upgrading and utilizing high-quality water sources.
Preferably, the reclaimed water tank is added with acid until the pH value is 0.8-1.8. The preferable pH value of the reclaimed water tank can ensure better nanofiltration effect.
Preferably, the electric adsorption module membrane of the electric adsorption component has a voltage of 1.2V-1.8V. The preferred electro-adsorption module membrane can achieve better electro-adsorption effect on voltage.
Preferably, when the water yield is less than or equal to 85%, the direction of the regenerated water flow in the electric adsorption component is the same as the direction of the working water flow; when the water yield is more than 85%, the direction of the regeneration water flow in the electric adsorption component is reverse to the direction of the working water flow. The flow direction is adjusted according to different water production rates, so that the water supply amount and the desalting effect can be guaranteed.
Preferably, the pH value of the concentrated water sent to the concentrated water tank by the nanofiltration component is 0.5-4.5, and the water yield of the nanofiltration component is controlled to be 10-40%; and adjusting the pH value of the concentrated water tank to 6.0-9.0 by using alkali liquor, and discharging the concentrated water tank after reaching the standard. The control of the pH value of the concentrated water is prior to the control of the water yield.
Preferably, the pH value of the concentrated water sent to the concentrated water tank by the nanofiltration component is 2.5-4.0. The nanofiltration water yield is controlled to be 10-25 percent.
Preferably, the acid solution can be nitric acid, sulfuric acid or hydrochloric acid, and the alkali solution is sodium hydroxide or potassium hydroxide.
More preferably, the acid solution is hydrochloric acid. The alkali liquor is sodium hydroxide. The environmental impact is less.
Compared with the prior art, the invention has the beneficial effects that: 1. the concentrated water after electric adsorption is subjected to nanofiltration treatment, partial acid in the concentrated water is separated from the concentrated water, the acidity of the concentrated water is reduced, and the consumption of alkali liquor for adjusting the pH value during discharge is reduced.
2. The concentrated water of the electric adsorption is subjected to nanofiltration treatment, partial salt in the concentrated water is separated from the concentrated water, the salt content of the concentrated water is reduced, the standard-reaching discharge of the total nitrogen in the concentrated water is ensured, and the problem that the total nitrogen of the concentrated water of the electric adsorption process is not up to the standard when the electric adsorption process is singly used is solved.
3. The concentrated water of the electric adsorption is subjected to nanofiltration treatment, and the nanofiltration effluent contains acid liquor and flows back to the water inlet tank, so that the acid addition of the electric adsorption regeneration can be reduced, part of the concentrated water is reduced, and the water yield is improved.
4. And part of the raw water and the produced water are blended and mixed, so that the consumption of alkali liquor for adjusting the pH value of the produced water can be reduced, and the produced water with different qualities can be supplied externally.
5. The process flow is short and the control is simple. The raw water is not subjected to hard pretreatment of alkali addition and calcium removal, so that the investment and the operation cost of the raw water are saved.
6. The nanofiltration component does not add scale inhibitor during operation, and no other pollutants are introduced except acid and alkali in the process.
7. Adopting an electro-adsorption process to treat raw water, wherein organic matters in the concentrated water are not concentrated; the nanofiltration treatment is adopted to electrically adsorb the concentrated water, the nanofiltration water yield is low, and the concentration multiple of organic matters in the nanofiltration concentrated water is low, so that the organic matters in the concentrated water can reach the standard for discharge.
Drawings
FIG. 1 is a schematic view of a moderate desalination apparatus according to the present invention.
Wherein, 1, former water piping 2, water inlet tank 3, electric adsorption component 4, well water tank 5, produce water tank 6, receive and strain subassembly 7, dense water tank.
Detailed Description
The invention is further illustrated by the following specific examples, of which example 1 is the best mode of practice.
Referring to figure 1: the moderate desalting device comprises a water inlet tank 2, a middle water tank 4, a water production tank 5, a concentrated water tank 7, an electric adsorption component 3 and a nanofiltration component 6, wherein the water inlet tank 2, the middle water tank 4, the water production tank 5 and the concentrated water tank 7 are all made of acid and alkali resistant materials or are lined with acid and alkali resistant protective layers; the water inlet tank 2 is connected with a raw water pipeline 1, the raw water pipeline 1 is also connected with a water production tank 5, the water production tank 5 is connected with an alkali liquor adding system, and the middle water tank 4 is connected with an acid liquor adding system and a water production external supply system; the water inlet tank 2 and the middle water tank 4 are respectively connected with the electric adsorption component 3 through pipelines provided with pipeline lifting pumps, the electric adsorption component 3 comprises an electric adsorption module, an interface pipeline valve of the electric adsorption module and an automatic control system, and a return pipeline is also connected between the electric adsorption component 3 and the middle water tank 4; the concentrated water outlet of the electric adsorption component 3 is connected with the nanofiltration component 6 through a pipeline provided with a pipeline lifting pump, the nanofiltration component 6 comprises a nanofiltration membrane and a pipeline valve and an automatic control system thereof, the water outlet of the nanofiltration component 6 is connected with the water inlet tank 2, the concentrated water outlet of the nanofiltration component 6 is connected with a concentrated water tank 7, and the concentrated water tank 7 is provided with an alkali liquor pipeline and a concentrated water discharge pipeline. Each pipeline lift pump is an acid and alkali corrosion resistant pump with acid resistance and a pH value of 0.5-3.0.
Example 1
The method is used for treating ion polluted underground water, the conductivity of raw water is 2300 mu s/cm, the total nitrogen is 10.0mg/L, and the COD20.1mg/L. After all raw water enters the water inlet tank to be buffered, the raw water is pumped into the electro-adsorption component by the lift pump to be treated, the voltage of an electro-adsorption component membrane is 1.6V, hydrochloric acid is added into the reclaimed water tank to adjust the pH value to be 1.8, the electro-adsorption water production rate is 90.0%, and after electro-adsorption concentrated water is subjected to nanofiltration filtration, the nanofiltration water production rate is controlled to be 25% by adopting a nanofiltration component with the aperture of 500D. At the moment, the electric conductivity of the electro-adsorption produced water is 700 mu s/cm, the total nitrogen is 8.5mg/L, the COD17.1mg/L and the pH value is 5.2; electro-adsorption concentrated water COD20.0mg/L, total nitrogen 36.3mg/L and pH value 2.4; the nanofiltration component has concentrated water COD25.5mg/L, total nitrogen 28.3mg/L and pH value 3. Adjusting the pH value of the water in the concentrated water tank to 6.0-9.0 by using alkali liquor, and discharging the water up to the standard. And adjusting the pH value of the water alkali liquor of the water production tank to 6.0-9.0, and then externally supplying. The total yield of the invention is 96.4%.
The dosage of 34% hydrochloric acid added per ton of water by the electro-adsorption component is 190 mL.
Example 2
The method is used for treating ion polluted underground water, the conductivity of raw water is 2300 mu s/cm, the total nitrogen is 10.0mg/L, and the COD20.1mg/L. After all raw water enters the water inlet tank to be buffered, the raw water is pumped into the electro-adsorption component by the lift pump to be treated, the voltage of an electro-adsorption component membrane is 1.8V, hydrochloric acid is added into the reclaimed water tank to adjust the pH value to be 0.8, the electro-adsorption water production rate is 90.0%, and after electro-adsorption concentrated water is subjected to nanofiltration filtration, the nanofiltration water production rate is controlled to be 10% by adopting a nanofiltration component with the aperture of 150D. At the moment, the electric conductivity of the electro-adsorption produced water is 630 mu s/cm, the total nitrogen is 7.9mg/L, the COD16.2mg/L and the pH value is 4.2; electro-adsorption concentrated water COD20.0mg/L, total nitrogen 31.2mg/L and pH value 1.9; the nanofiltration component has concentrated water COD22.1mg/L, total nitrogen 28.8mg/L and pH value 2.8. Adjusting the pH value of the water in the concentrated water tank to 6.0-9.0 by using alkali liquor, and discharging the water up to the standard. And adjusting the pH value of the water alkali liquor of the water production tank to 6.0-9.0, and then externally supplying. The total yield of the invention is 96.0%.
Example 3
When the method is used for treating surface water, the conductivity of raw water is 1300 mu s/cm, the total nitrogen is 11.0mg/L, and the total nitrogen is COD2.0 mg/L. After all raw water enters the water inlet tank to be buffered, the raw water is pumped into the electro-adsorption component by the lift pump to be treated, the membrane pair voltage of the electro-adsorption component is 0.5V, hydrochloric acid is added into the reclaimed water tank to adjust the pH value to be 0.5, the electro-adsorption water production rate is 95.0%, the electro-adsorption concentrated water is subjected to nanofiltration filtration, and then a nanofiltration component with the aperture of 100D is adopted, and the nanofiltration water production rate is controlled to be 10%. At the moment, the electric conductivity of the electro-adsorption produced water is 420 mu s/cm, the total nitrogen is 10.5mg/L, the COD1.0mg/L and the pH value is 4.2; electro-adsorption concentrated water COD1.8mg/L, total nitrogen 30.2mg/L and pH value 2.2; the nanofiltration component has concentrated water COD2.0mg/L, total nitrogen 24.8mg/L and pH value 0.5. Adjusting the pH value of the water in the concentrated water tank to 6.0-9.0 by using alkali liquor, and discharging the water up to the standard. And adjusting the pH value of the water alkali liquor of the water production tank to 6.0-9.0, and then externally supplying. The total yield of the invention is 92.5%.
Example 4
When the method is used for treating surface water, the conductivity of raw water is 1300 mu s/cm, the total nitrogen is 11.0mg/L, and the total nitrogen is COD2.0 mg/L. 90% of raw water enters a water inlet tank to be buffered, and then is pumped into an electric adsorption component by a lift pump to be processed, the electric adsorption component has a membrane pair voltage of 2.0V, hydrochloric acid is added into a reclaimed water tank to adjust the pH value to 3.0, the electric adsorption water yield is 95.0%, and after electric adsorption concentrated water is subjected to nanofiltration filtration, a nanofiltration component with the aperture of 1000D is adopted, and the nanofiltration water yield is controlled to be 40%. At the moment, the electric conductivity of the electro-adsorption produced water is 420 mu s/cm, the total nitrogen is 10.5mg/L, the COD1.0mg/L and the pH value is 4.2; electro-adsorption concentrated water COD1.8mg/L, total nitrogen 30.2mg/L and pH value 2.2; the nanofiltration component has concentrated water COD2.0mg/L, total nitrogen 24.8mg/L and pH 4.5. Adjusting the pH value of the water in the concentrated water tank to 6.0-9.0 by using alkali liquor, and discharging the water up to the standard. 10% of the water amount of the raw water enters a water production tank, the water alkali liquor of the water production tank is used for external supply after the pH value is adjusted to 6.0-9.0, and the conductivity of the external supply water is 500 mu s/cm. The total yield of the invention is 90.9%.
Comparative example 1
The partial flow of the invention is adopted to treat ion polluted underground water, the conductivity of raw water is 2300 mu s/cm, the total nitrogen is 10.0mg/L, and the COD20.1mg/L. After all raw water enters the water inlet tank for buffering, the raw water is pumped into the electric adsorption component by the lift pump for treatment, and concentrated water of the electric adsorption component directly enters the concentrated water tank without passing through the nanofiltration component. The voltage of the electro-adsorption component membrane pair is 1.6V, hydrochloric acid is added into a reclaimed water tank to adjust the pH value to be 1.8, and the electro-adsorption water production rate is 90.0%. At the moment, the conductivity of the electro-adsorption produced water is 660 mu s/cm, the total nitrogen is 4.5mg/L, the COD17.1mg/L and the pH value is 5.2; the electro-adsorption concentrated water COD20.0mg/L, the total nitrogen 60.0mg/L and the pH value 2.4. After the pH value of the water in the concentrated water tank is adjusted to 6.0-9.0 by using the alkaline liquor, the total nitrogen can not be directly discharged because the total nitrogen exceeds the local discharge standard of 30 mg/L. And adjusting the pH value of the water alkali liquor of the water production tank to 6.0-9.0, and then externally supplying. The total water yield is 90.0% of the water yield of the electro-adsorption process.
The dosage of 34% hydrochloric acid per ton of water for the electro-adsorption module in the comparative example was 280mL, which is higher than 190mL in example 1. The pH value of the electro-adsorption concentrated water is 2.4, the pH value of the nano-filtration concentrated water in the example 1 is 3.5, and the water amount is lower than that of the electro-adsorption concentrated water, so the alkali liquor amount for adjusting the concentrated water to be neutral in the comparative example is also higher than that in the example 1.
Comparative example 2
The method is used for treating ion polluted underground water, the conductivity of raw water is 2300 mu s/cm, the total nitrogen is 10.0mg/L, and the COD20.1mg/L. After all raw water enters the water inlet tank to be buffered, the raw water is pumped into the electro-adsorption component by the lift pump to be treated, the voltage of an electro-adsorption component membrane is 1.6V, hydrochloric acid is added into the reclaimed water tank to adjust the pH value to be 1.8, the electro-adsorption water production rate is 90.0%, and after electro-adsorption concentrated water is subjected to nanofiltration filtration, the nanofiltration water production rate is controlled to be 60% by adopting a nanofiltration component with the aperture of 500D. At the moment, the conductivity of the electro-adsorption produced water is 850 mu s/cm, the total nitrogen is 9.9mg/L, the COD17.1mg/L and the pH value is 4.2; electro-adsorption concentrated water COD20.0mg/L, total nitrogen 7.6mg/L and pH value 2.4; the nanofiltration component has concentrated water COD25.5mg/L, total nitrogen 7.3mg/L and pH value 6.0. When the water yield is controlled to be 60% in the nanofiltration operation, the pressure at the nanofiltration inlet is gradually increased, and the continuous and stable operation cannot be realized. The reason is that the nanofiltration concentrated water has over-high ion concentration and high pH value, and the hard calcium and other ions are deposited to cause the fouling of the nanofiltration membrane.
The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.
Claims (10)
1. A moderate desalting device is characterized in that: the device comprises a water inlet tank (2), a middle water tank (4), a water production tank (5), a concentrated water tank (7), an electric adsorption component (3) and a nanofiltration component (6), wherein the water inlet tank (2) is connected with a raw water pipeline (1), the raw water pipeline (1) is also connected with the water production tank (5), the water production tank (5) is connected with an alkali liquor adding system, and the middle water tank (4) is connected with an acid liquor adding system and a water production external supply system; the water inlet tank (2) and the middle water tank (4) are respectively connected with the electric adsorption component (3) through a pipeline provided with a pipeline lift pump, wherein a return pipeline is also connected between the electric adsorption component (3) and the middle water tank (4); the concentrated water outlet of the electric adsorption component (3) is connected with the nanofiltration component (6) through a pipeline provided with a pipeline lifting pump, the water production port of the nanofiltration component (6) is connected with the water inlet tank (2), the concentrated water port of the nanofiltration component (6) is connected with the concentrated water tank (7), and the concentrated water tank (7) is provided with an alkali liquor pipeline and a concentrated water discharge pipeline.
2. A moderate salt removing device according to claim 1, wherein: the water inlet tank (2), the middle water tank (4), the water production tank (5) and the concentrated water tank (7) are made of acid and alkali resistant materials or lined with acid and alkali resistant protective layers.
3. A moderate salt removing device according to claim 1, wherein: each pipeline lift pump is an acid and alkali corrosion resistant pump with acid resistance and a pH value of 0.5-3.0.
4. A moderate salt removing device according to claim 1, wherein: the nanofiltration component (6) comprises a nanofiltration membrane, a pipeline valve of the nanofiltration membrane and an automatic control system, and the aperture of the nanofiltration membrane is 100-1000D.
5. A moderate salt removing device according to claim 4, wherein: the aperture of the nanofiltration membrane is 150-500D.
6. A moderate salt removing device according to claim 1, wherein: the electric adsorption component (3) comprises an electric adsorption module, an interface pipeline valve of the electric adsorption module and an automatic control system.
7. A moderate desalination process using the apparatus of any one of claims 1 to 6, characterized in that: after 60% -95% of raw water enters the water inlet tank (2) for buffering, pumping the raw water into the electric adsorption component (3) by a pipeline lift pump for regeneration treatment, controlling the electric adsorption module membrane of the electric adsorption component (3) to have a voltage of 0.5-2.0V, and conveying the produced water treated by the electric adsorption component (3) to the water production tank (5) for standby;
the regeneration treatment in the electric adsorption component (3) is divided into two stages: in the first stage, the water in the middle water tank (4) is pumped into the electric adsorption component (3), and at the moment, the effluent of the electric adsorption component (3) is used as electric adsorption concentrated water and sent to the nanofiltration component (6) for treatment; in the second stage of regeneration, water in the water inlet tank (2) is pumped into the electric adsorption component (3), at the moment, the water outlet of the electric adsorption component (3) is sent to the middle water tank (4), acid is added into the middle water tank (4) until the pH value is 0.5-3.0, and the water is regenerated and used in the first stage next time; the electric adsorption component (3) regenerates the electric adsorption concentrated water sent to the nanofiltration component (6) in the first stage, and nanofiltration water mainly containing hydrogen chloride, sodium nitrate and sodium chloride returns to the water inlet tank (2) after nanofiltration filtration;
mixing water in the water production tank (5) with raw water, adjusting the pH value with alkali liquor, and supplying the mixture; concentrated water generated by the nanofiltration component (6) is sent to a concentrated water tank (7), and the water in the concentrated water tank is discharged after reaching the standard after the pH value is adjusted by alkali liquor.
8. A mild desalination process according to claim 7, wherein: when the water yield is less than or equal to 85 percent, the direction of the regenerated water flow in the electric adsorption component (3) is the same as the direction of the working water flow; when the water yield is more than 85 percent, the direction of the regenerated water flow in the electric adsorption component (3) is reverse to the direction of the working water flow.
9. The method of claim 7, wherein: the pH value of concentrated water sent to the concentrated water tank (7) by the nanofiltration component (6) is 0.5-4.5, and the water yield of the nanofiltration component (6) is controlled to be 10-40%; and the concentrated water tank (7) is used for adjusting the pH value to 6.0-9.0 by using alkali liquor and then is discharged after reaching the standard.
10. The method of claim 7, wherein: the acid solution can be nitric acid, sulfuric acid or hydrochloric acid, and the alkali solution is sodium hydroxide or potassium hydroxide.
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