CN110845050A - A device and method for treating low-concentration COD wastewater - Google Patents

Abstract

The invention discloses a device and a method for treating low-concentration COD wastewater. The device comprises a collection tank for collecting wastewater, an oxidation tank for catalytic oxidation reaction, and a concentration for removing residual hydrogen peroxide, which are connected in sequence. A tank, a tubular membrane for separating substances in water and producing clean water, and a clean water tank for receiving effluent, the oxidation tank is filled with activated carbon and hydrogen peroxide as catalysts and adsorbents, and a mixer is installed, the concentrated Sodium bisulfite, which adjusts the redox potential, is added to the pool. Through the recycling of the catalyst, the invention reduces the usage amount of the catalyst, widens the pH applicable range of the reaction system, simplifies the technological process, improves the quality of the effluent, and ensures the stability of the effluent.

Description

A device and method for treating low-concentration COD wastewater

technical field

The invention relates to the field of wastewater treatment, in particular to a device and method for treating low-concentration COD wastewater.

Background technique

With the improvement of environmental protection requirements, wastewater discharge standards are also constantly improving. The removal of pollutants by conventional wastewater treatment processes only transfers pollutants from one form to another, and cannot be completely removed. And after the conventional wastewater treatment process, the removal of effluent COD will reach the limit, and the conventional process has been unable to remove this type of refractory organic pollutants. However, the current improvement of wastewater discharge standards, and if the wastewater is to be reused after advanced treatment, there are higher requirements for the COD of the treated wastewater, which cannot be met by traditional treatment processes.

Therefore, advanced oxidation technology is widely used to further remove this type of refractory organic pollutants. The mechanism of this oxidation process is mainly based on the formation of hydroxyl radicals, and then the hydroxyl radicals are used to degrade organic pollutants in water into carbon dioxide and water. carbon dioxide. The most common advanced oxidation process is the Fenton method. During the Fenton reaction, under the catalysis of ferrous iron, hydrogen peroxide is decomposed to generate hydroxyl radicals. Because of its extremely high oxidation potential, complex organic compounds can be oxidized and decomposed by means of electron transfer. The Fenton reaction can effectively degrade organic substances into small molecular substances, but the disadvantage is that the utilization rate of hydrogen peroxide is not high, the salinity of organic substances is low, the applicable pH value range is narrow, and a high catalyst input is required.

Therefore, it is necessary to make improvements on this basis, and to provide a new type of device and method, which can improve the utilization rate of the catalyst and ensure the stability of the effluent.

SUMMARY OF THE INVENTION

The purpose of the present invention is to overcome the defects of the prior art, provide a device and method for treating low-concentration COD wastewater, improve the quality of the effluent, and ensure the stability of the effluent.

In order to achieve the above-mentioned purpose, the present invention proposes the following technical scheme: a device for processing low-concentration COD wastewater, which comprises a collection tank for collecting wastewater that is connected in turn, an oxidation tank for catalytic oxidation reaction, and is used for removing residual waste water. A concentration tank for hydrogen oxide, a tubular membrane for separating substances in water and producing clean water, and a clean water tank for receiving effluent; activated carbon and hydrogen peroxide as catalysts and adsorbents are added in the oxidation tank, and the concentration tank Added sodium bisulfite to adjust the redox potential.

Preferably, a lift pump is also included, the lift pump is connected to the collection tank and the oxidation tank, and is used for transporting the waste water in the collection tank to the oxidation tank.

Preferably, a circulating pump is also included, the circulating pump is connected to the concentration tank and the tubular membrane, and is used for transporting the water in the concentration tank to the tubular membrane.

Preferably, the concentration tank is also connected with a sludge pump, and the sludge pump is connected with a sludge collection tank for discharging sludge to the sludge collection tank.

Preferably, the activated carbon acts both as a catalyst and as an adsorbent.

A method for treating low-concentration COD wastewater, comprising the steps of:

S1, collect the waste water in the collection tank, and transport it to the oxidation tank through the lift pump;

S2, adding activated carbon and hydrogen peroxide to the oxidation tank, stirring with a mixer in the oxidation tank, and transporting the oxidized wastewater to the concentration tank.

S3, adding sodium bisulfite in the concentration tank for reacting with excess hydrogen peroxide, thereby adjusting the redox potential in the water, and sending the treated water into the tubular membrane;

S4, remove the activated carbon particles in the wastewater in the tubular membrane, separate the activated carbon, and re-add the separated activated carbon particles into the oxidation tank;

S5, the treated water is collected in a clear water tank, and the clear water tank determines the water quality after treatment.

Preferably, in S2, the ratio of hydrogen peroxide to activated carbon is in the range of 200:1-60:1, and the redox potential is in the range of 600-650mv.

Preferably, in S2, the stirring speed range of the mixer is 60-80rpm, and the stirring time range is 1-3h.

Preferably, in S3, the adjustment range of the redox potential is: 90-110mv.

Preferably, in S5, the water entering the clear water pool is determined to be discharged up to the standard or reused after advanced treatment.

The beneficial effects of the present invention are:

1. The device and method for treating low-concentration COD wastewater according to the present invention reduces the amount of catalyst used, can be applied to a wide range of pH values, and can realize the recycling of catalysts.

2. The energy consumption of the whole device is reduced, the equipment is easy to use and maintain, and automatic operation is realized.

Description of drawings

Fig. 1 is the structural representation of a kind of device for processing low-concentration COD wastewater of the present invention;

2 is a schematic flow diagram of a method for treating low-concentration COD wastewater according to the present invention.

Reference numerals: 1. Device for treating low-concentration COD wastewater, 11, collection tank, 12, oxidation tank, 13, concentration tank, 14, tubular membrane, 15, clean water tank, 16, lift pump, 17, circulating pump, 18. Sludge pump, 19. Discharge pump.

Detailed ways

The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings of the present invention.

As shown in FIG. 1 , a device 1 for treating low-concentration COD wastewater disclosed in the present invention uses activated carbon as a catalyst to obtain effluent with better water quality after a series of treatment steps. The device 1 for treating low-concentration COD wastewater includes a collection tank 11, an oxidation tank 12, a concentration tank 13, a tubular membrane 14, and a clear water tank 15 connected in sequence. After the low-concentration COD wastewater passes through the above-mentioned device 1, the The effluent that can be discharged up to the standard or reused after advanced treatment.

The collection tank 11 is used to receive low-concentration COD wastewater, the collection tank 11 is connected to the oxidation tank 12 through a lift pump 16, and the waste water is transported into the oxidation tank 12 through the lift pump 16, The oxidation tank 12 is used to catalyze the oxidation reaction and degrade the COD wastewater. A certain amount of activated carbon and hydrogen peroxide are added to the oxidation tank 12. The activated carbon is used as a catalyst and an adsorbent, and the dosage is based on different types of wastewater. For adjustment, the activated carbon and hydrogen peroxide are used as catalysts to achieve a wider range of application of the pH value, which is adjusted by adding NaOH or H ₂ SO ₄ . The activated carbon will have a small amount of loss in the catalytic effect with the prolongation of the catalytic time, so a part of it needs to be discharged regularly, and new activated carbon should be replenished to make the entire device 1 more thorough and effective in the process of treating wastewater. The oxidation tank 12 is provided with a mixer (not shown in the figure), and the stirring time and stirring speed of the mixer are adjusted according to different types of waste water. When the activated carbon is used as an adsorbent, the pollutants in the waste water are adsorbed on the surface of the activated carbon. At the same time, the activated carbon catalyzes the decomposition of hydrogen peroxide to form hydroxyl radicals, and on the solid-liquid interface, the hydroxyl radicals react and degrade with pollutants, and the reaction efficiency is improved. The concentration tank 13 is connected to the oxidation tank 12 for removing residual hydrogen peroxide, circulating the reaction solution, and increasing the fixed suspension concentration. The wastewater in the oxidation tank 12 is catalyzed and stirred into the concentration The pool 13, the concentration pool 13 is used to remove the hydrogen peroxide remaining after the reaction, so as not to affect the effect of the subsequent treatment process. In the concentration tank 13, by adding sodium bisulfite as a balancing agent for balancing water quality, it reacts with excess hydrogen peroxide, so that the oxidation-reduction potential (ORP) in the water quality is controlled at 90-110mv, thereby realizing more efficient treatment of wastewater. completely.

The tubular membrane 14 is connected to the concentration tank 13 through a circulating pump 17. The tubular membrane 14 is used to separate the activated carbon particles in the water to generate circulating concentrated water, so that the separated circulating concentrated water containing the activated carbon particles can be regenerated. It is added into the oxidation tank 12 connected with the tubular membrane 14 to improve the utilization rate and reduce the usage of activated carbon. The clean water generated by the tubular membrane 14 enters the clean water pool 15 , one end of the clean water pool 15 is connected to the tubular membrane 14 , and the other end is connected to a discharge pump 19 . The water in the clear water tank 15 is treated differently according to the water quality. If the water reaches the standard, it will be discharged. If the water does not meet the standard, it can be reused after intensive treatment.

The concentration tank 13 is also connected to a sludge pump 18, which is connected to a sludge collection tank (not shown), and the sludge pump 18 is used to receive waste water generated after the concentration tank 13 reacts. The sludge is transported to the sludge collection tank, and then subjected to pressure filtration and dehydration treatment, so as to process the generated sludge, and the generated sludge is activated carbon sludge, which is regularly used for activated carbon with poor catalytic effect. Recycling treatment is carried out to make the reaction more thorough and ensure the quality of the effluent.

As shown in Figure 2, a method for treating low-concentration COD wastewater disclosed by the present invention comprises the following steps:

S1, the waste water is collected in the collection tank 11, and transported to the oxidation tank 12 through the lift pump 16;

S2, add a certain amount of activated carbon and hydrogen peroxide in the oxidation tank 12, stir with the mixer in the oxidation tank 12, and transport the oxidized wastewater to the concentration tank 13;

S3, adding sodium bisulfite in the concentration tank 13, for reacting with excess hydrogen peroxide, thereby regulating the redox potential in the water, and sending the treated water into the tubular membrane 14;

S4, removing the activated carbon particles in the waste water in the tubular membrane 14, separating the activated carbon, and re-adding the separated activated carbon particles into the oxidation tank 12;

S5, the treated water is collected in the clear water tank 15, and the clear water tank 15 judges the treated water quality, and if it reaches the discharge standard, it is discharged through the discharge pump 19, and if it does not meet the discharge standard, it is discharged through the discharge pump 19 is discharged to subsequent devices for advanced treatment and reused.

Specifically, in S2, after the wastewater is transported to the oxidation tank 12, activated carbon and hydrogen peroxide are added, and the rotation speed and time of the mixer in the oxidation tank 12 can also be adjusted according to the wastewater with different concentrations of COD. The ratio of hydrogen peroxide to activated carbon is in the range of 200:1-60:1, the stirring speed of the mixer is in the range of 60-80rpm, and the stirring time is in the range of 1-3h. The oxidation reaction that takes place in the oxidation tank 12 makes the redox potential range of 600-650mv. Further, NaOH or H ₂ SO ₄ is added in the oxidation tank 12 to adjust the pH value to meet the pH value requirements of COD wastewater with different concentrations. In S3, the redox potential is controlled at 90-110mv by adding sodium bisulfite, and the residual hydrogen peroxide is removed so as not to affect the effect of the subsequent treatment process. In S4, circulating concentrated water and clean water are produced in the tubular membrane, and the circulating concentrated water contains activated carbon particles and is re-added into the oxidation tank, so as to make recycling and reduce the usage of chemicals; the clean water is fed into in the clear water pool. In S5, the water in the clear water tank 15 needs to be judged to confirm whether it meets the discharge standard.

Example 1:

When the biochemical effluent with a COD concentration of about 200mg/L is collected in the collection tank 11, it is transported to the oxidation tank 12 by the lift pump, and then NaOH or H ₂ SO ₄ is added in the oxidation tank 12 to adjust the pH value to 7. The amount of hydrogen peroxide added in the oxidation tank 12 is 300mg/L, and the amount of activated carbon is 2-5mg/L. The redox potential at this time is controlled at 600-650mv. , transported to the concentration tank 13, and sodium bisulfite was added in the concentration tank 13, so that the redox potential returned to 90-110mv, and after the treatment, it was transported to the clear water tank 15 through the tubular membrane 14, and the COD concentration at this time could be reduced to 30mg/ L, the COD removal rate is 85%.

Embodiment 2:

When the biochemical effluent with a COD concentration of about 150mg/L is collected in the collection tank 11, it is transported to the oxidation tank 12 by the lift pump 16, and then NaOH or H ₂ SO ₄ is added in the oxidation tank 12 to adjust the pH value to 8 -8.5, the amount of hydrogen peroxide added in the oxidation tank 12 is 250-300mg/L, the amount of activated carbon added is 2-5mg/L, the redox potential at this time is controlled at 600-650mv, and the wastewater in the oxidation tank 12 is passed through a mixer to After stirring at 80 rpm for 2 hours, it was transported to the concentration tank 13, and sodium bisulfite was added in the concentration tank 13 to make the redox potential return to 90-110mv, and after the treatment, it was transported to the clear water tank 15 through the tubular membrane 14, and the COD concentration at this time was It can be reduced to 50mg/L, and the COD removal rate is 67%.

Embodiment three:

When the biochemical effluent with a COD concentration of about 300mg/L is collected in the collection tank 11, it is transported to the oxidation tank 12 by the lift pump, and then NaOH or H ₂ SO ₄ is added in the oxidation tank 12 to adjust the pH value to 3. The amount of hydrogen peroxide added in the oxidation tank 12 is 500-600mg/L, the amount of activated carbon is 5-10mg/L, the redox potential at this time is controlled at 600-650mv, and the waste water in the oxidation tank 12 is stirred by a mixer at a speed of 80rpm After 2 hours, it is transported to the concentration tank 13, and sodium bisulfite is added in the concentration tank 13 to make the redox potential return to 90-110mv. 80mg/L, the COD removal rate is 73%.

The treatment process of the invention enables the activated carbon to effectively realize recycling, and simplifies the technological process, improves the quality of the effluent, and also improves the stability of the effluent.

The technical content and technical features of the present invention have been disclosed as above. However, those skilled in the art may still make various replacements and modifications based on the teaching and disclosure of the present invention without departing from the spirit of the present invention. Therefore, the protection scope of the present invention should not be limited to The contents disclosed in the embodiments should include various substitutions and modifications without departing from the present invention, and are covered by the claims of this patent application.

Claims (10)

1. a device for processing low-concentration COD waste water, is characterized in that, comprises the collection pond that is connected successively for collecting waste water, is used for the oxidation pond of catalytic oxidation reaction, is used for removing the concentration pond of residual hydrogen peroxide, uses A tubular membrane for separating substances in water and producing clear water, and a clear water tank for receiving effluent; activated carbon and hydrogen peroxide as catalysts and adsorbents are added in the oxidation tank, and an oxidation-reduction potential adjustment is added in the concentration tank. of sodium bisulfite. 2. The device for processing low-concentration COD wastewater according to claim 1, further comprising a lift pump, which connects the collection tank and the oxidation tank, and is used for transporting the waste water in the collection tank to the oxidation tank. in the pool. 3. The device for processing low-concentration COD wastewater according to claim 1, further comprising a circulating pump, which connects the concentration tank and the tubular membrane, and is used for conveying the water in the concentration tank to the tubular membrane. membrane. 4. The device for treating low-concentration COD wastewater according to claim 1, wherein the concentration tank is also connected with a sludge pump, and the sludge pump is connected with a sludge collection tank, which is used for collecting sewage. The sludge is discharged to the sludge collection tank. 5. The device for processing low-concentration COD wastewater according to claim 1, wherein the oxidation tank is provided with a mixer that stirs the activated carbon and hydrogen peroxide, and the activated carbon is used both as a catalyst and as a adsorbent. 6. a method for processing low-concentration COD waste water, is characterized in that, comprises the steps: S1, collect the waste water in the collection tank, and transport it to the oxidation tank through the lift pump; S2, add a certain amount of activated carbon and hydrogen peroxide in the oxidation tank, stir with a mixer in the oxidation tank, and transport the oxidized wastewater to the concentration tank; S3, adding a certain amount of sodium bisulfite in the concentration tank for reacting with excess hydrogen peroxide, thereby adjusting the redox potential in the water, and sending the treated water into the tubular membrane; S4, remove the activated carbon particles in the wastewater in the tubular membrane, separate the activated carbon, and re-add the separated activated carbon particles into the oxidation tank; S5, the treated water is collected in a clear water tank, and the clear water tank determines the water quality after treatment. 7. the method for processing low-concentration COD wastewater according to claim 6, is characterized in that, in S2, the ratio scope of adding hydrogen peroxide and activated carbon is 200:1-60:1, and the redox potential scope is 600-650mv . 8. The method for treating low-concentration COD wastewater according to claim 6, wherein in S2, the stirring speed range of the mixer is: 60-80rpm, and the stirring time range is 1-3h. 9 . The method for treating low-concentration COD wastewater according to claim 6 , wherein, in S3, the redox potential adjustment range is: 90-110mv. 10 . 10. The method for treating low-concentration COD wastewater according to claim 6, characterized in that, in S5, the water entering the clear water tank is judged to be discharged up to standard or reused after advanced treatment.

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