CN102674505B - Special equipment for treating organic sewage by utilizing electro-Fenton reaction - Google Patents

Abstract

The invention discloses a special equipment for treating organic sewage by using electric Fenton reaction. It is provided with a tower reactor with a double-layer tower body with an inner tower wall and an outer tower wall. It is realized by the graphite rod anode between the tower wall and the outer tower wall, as well as the aeration head and the water distribution pipe at the bottom of the inner tower. Since the present invention uses the treated scrap iron as the cathode, it overcomes the disadvantages of complex electrode material preparation process, high price, high equipment investment and operating costs, and at the same time makes the cathode have higher specific surface area, reaction rate and sewage mass transfer efficiency. , not only effectively improve the treatment effect and efficiency of organic pollutants in sewage, but also do not need to add oxidants and catalysts, further saving energy and reducing consumption. Compared with the prior art, it has outstanding substantive features and remarkable progress. It also has the advantages of novel and unique inventive concepts, compact and reasonable structural design, stable and reliable working performance, simple and easy operation and control, remarkable economic and practical benefits, broad application prospects, and suitable for industry promotion.

Description

A special equipment for treating organic sewage by using electro-Fenton reaction

technical field

The invention belongs to the technical field of treating organic polluted sewage by electrochemical reaction, and in particular relates to a device for treating organic sewage by Fenton method.

Background technique

With the development of society, the effective treatment and utilization of organic sewage has become a common concern. In recent years, the state has attached great importance to environmental governance, which has made many enterprises attach great importance to their own water treatment, and urgently needs to provide corresponding sewage treatment technology and equipment to meet the needs of energy saving, emission reduction, and sewage treatment.

For a long time, the treatment of biorefractory organic wastewater has always been a difficult point in environmental governance. Traditional biological methods are powerless in dealing with such organic matter. The methods widely used today include coagulation precipitation, adsorption, chemical oxidation, ion exchange, etc., but they all need to consume a lot of chemicals and raw materials, the cost is high, the operation is complicated, and there are secondary pollution problems.

Advanced oxidation process (Advanced Oxidation Process, referred to as AOPs), also known as deep oxidation technology, has gradually attracted the attention of all countries in the world because of its advantages of fast reaction speed, complete treatment, pollution-free, wide application range, and has carried out research in this direction. Research and development work. At present, it is generally believed that this process is characterized by the generation of hydroxyl radicals with strong oxidizing ability. Under the reaction conditions of high temperature, high pressure, electricity, ultrasound, light irradiation, catalysts, etc., the macromolecular refractory organic compounds are oxidatively degraded into low-toxic or Non-toxic small molecules are even completely mineralized into carbon dioxide and water. Among many advanced oxidation processes, Fenton’s advanced oxidation process is relatively mature, simple, and can be realized without special equipment, and iron, as the reactant and catalyst of oxidation reaction, has economic advantages, so it has gradually attracted domestic and foreign attention. Pay attention to. However, the simple Fenton advanced oxidation technology for treating high-concentration organic wastewater also has its unsatisfactory features, such as the need to use higher concentrations of hydrogen peroxide and catalysts and consume a large amount, which makes the treatment cost higher and produces More iron-containing sludge needs to be treated, which still limits the popularization and application. The cathodic electro-Fenton technology generates hydrogen peroxide through cathode aeration, and at the same time, the surface of the cathode reduces Fe ³⁺ to Fe ²⁺ to form a Fenton reaction zone near the cathode in the electrolytic cell. At the same time, the anode can also degrade some organic matter through electro-oxidation, so Electro-Fenton technology overcomes the disadvantages of traditional Fenton treatment technology, and at the same time, through proper process adjustment, it can realize the harmless transformation of most refractory organic substances. Electro-Fenton process can be used as the main treatment technology of industrial organic wastewater, wastewater pretreatment or advanced treatment technology, and it has broad application prospects.

At present, according to the data, the cathodic electric Fenton water treatment equipment can be composed of reaction tank, cathode, anode, aeration equipment and other devices. Although it can treat organic polluted sewage, it still has the problems of large floor area, high energy consumption, complicated and expensive electrode material preparation process, resulting in high equipment investment and operating costs.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art, and provide a special equipment for treating organic sewage by electro-Fenton reaction with small footprint, cheap electrode materials, and low investment and operation costs.

The purpose of the present invention will be achieved through the following technical solutions: it includes a DC power supply, a water inlet pipe, a water outlet pipe, and an exhaust valve, and also includes a tower reactor with a double-layer tower body with an inner tower wall and an outer tower wall. Iron filings cathode in the tower wall, graphite rod anode between the inner tower wall and the outer tower wall, and the aeration head and water distribution pipe at the bottom of the inner tower.

In the present invention, the cathode made of treated waste iron chips is filled in the inner tower wall, and graphite rods are used as anodes. By aerating the inner tower, the sewage forms an inner tower between the inner tower and the outer tower in the tower reactor. Circulating flow makes oxygen molecules effectively reduce on the surface of the cathode to generate hydrogen peroxide, and hydrogen peroxide reacts with a certain amount of ferrous ions or iron ions in sewage to achieve the purpose of degrading organic pollutants in sewage. Compared with the prior art, the present invention has the following advantages and beneficial effects:

1. Since the present invention uses the treated scrap iron as the cathode, it not only makes full use of the waste, reduces the cost, but also overcomes the disadvantages of complex electrode material preparation process and high price in the prior art, resulting in high equipment investment and operating costs , and the iron filings cathode has a higher specific surface area than the traditional electrode, which can effectively improve the reaction rate, treatment effect and efficiency of organic pollutants in sewage. Compared with the prior art, it has outstanding substantive features and remarkable progress.

2, because the present invention utilizes the scrap iron filings after processing as negative electrode, in the cathodic electro-Fenton reaction of sewage treatment, it uses the iron filings after processing as reactant and catalyzer of oxidation, does not need to add oxidizing agent and catalyzer in addition, can further Save energy and reduce costs. Moreover, the problems of large hydrogen peroxide and catalyst consumption, high treatment cost, generation of iron-containing sludge to be treated, and limited popularization and application in the prior art are completely solved. Still has outstanding substantive features and significant progress.

3. Since the present invention adopts a tower reactor structure with an inner tower wall and an outer tower wall double-layer tower body, the sewage can form an internal circulation flow between the inner tower and the outer tower of the tower reactor, thereby effectively improving The mass transfer efficiency of the sewage enables the organic matter in the sewage to fully contact and react with the hydroxyl radicals produced by the cathode electro-Fenton reaction, which significantly improves the sewage purification effect.

4. Since the present invention adopts a tower reactor structure with a double-layer tower body with inner tower wall and outer tower wall, compared with ordinary reaction tanks, it not only occupies a small area, but also has fast reaction speed, high working efficiency and excellent treatment effect. Good highlight.

5. Since the present invention adopts the structure of setting diversion holes on the inner tower wall, the inner circulation flow effect of the tower reactor can be enhanced, thereby accelerating the reaction and effectively improving the treatment efficiency.

6. In addition to the above-mentioned features, the present invention also has the advantages of novel and unique inventive concept, compact and reasonable structural design, stable and reliable working performance, simple and easy operation and control, significant economic and practical benefits, quite broad application prospects, and suitable for industry promotion.

Description of drawings

Fig. 1 is a structural representation of the present invention;

Fig. 2 is a top view structural schematic diagram of the present invention.

Detailed ways

A special equipment for treating organic sewage by using electric Fenton reaction of the present invention is a tower reactor composed of a double-layer tower body with an inner tower wall 4 and an outer tower wall 1, and the outside of the tower reactor is fixed with Water inlet pipe 11, water outlet pipe 6, top exhaust valve 9 and bottom air supply pipe 7. In the inner tower wall 4, that is, in the inner tower, there is an iron filing cathode 3 composed of processed iron filings, and an anode 5 made of a graphite rod is arranged between the inner tower wall 4 and the outer tower wall 1, and the anode 5 and the cathode 3 are respectively connected to the positive pole and the negative pole of the external DC power supply 10. An aeration head 8 and a water distribution pipe 12 connected to the air supply pipe 7 and the water inlet pipe 11 are respectively arranged at the bottom of the inner tower.

The iron scrap cathode 3 is made of scrap iron scrap produced by metal processing, and is cleaned with 10% mass concentration of dilute hydrochloric acid for 20 minutes to remove surface oil, and then rinsed with clean water until the pH value of the washed water is 6-8, and then Metal Ag or Ti is chemically deposited on the surface to form an electro-Fenton bimetallic cathode. It is filled in the inner tower with a bulk density of 2.0T/m ³ to 2.5T/m ³ . And the iron filing cathode 3 is connected to the negative pole of the DC power supply 10 with a wire. The anode 5 placed between the inner tower wall 4 and the outer tower wall 1 is a graphite rod with a diameter of 1 cm to 5 cm, the number of which can be 3 to 8, and is connected to the positive pole of the DC power supply 10 . The distance between the graphite rod and the outer wall of the inner tower is 1cm to 10cm. If the distance is too large, the current efficiency will decrease. In order to increase the current efficiency between the cathode 3 and the anode 5, evenly distributed diversion holes 2 are arranged on the inner tower wall 4. The diameter of the diversion holes 2 is 1 cm to 5 cm, and the total opening ratio on the inner tower wall 4 is 10. %~20%.

The output voltage of the DC power supply 10 is between 3V and 36V, and the power requirement matches the scale of sewage treatment. Taking the treatment of 1 cubic meter of sewage per hour as an example, the maximum power requirement is between 800W and 1000W. The size of the aerator head 8 should match the diameter of the inner tower body, and get final product slightly smaller than the inner diameter of the inner tower body. The pressure of the gas supply system should match the height of the tower, and the minimum pressure should be greater than the sum of the water pressure at the bottom of the tower and the pressure loss of the gas supply pipeline. The air supply volume is 0.1～0.3 m ³ /h.

Using the present invention, the pH value of the sewage should be 2 to 4, and have a certain supporting electrolyte concentration to achieve the effect of increasing the current, and select the appropriate ferrous ion concentration according to different sewage water quality, so when the sewage enters the tower reaction The sewage should be regulated before the reactor to make it reach the specified reaction conditions. For example, for organic polluted sewage with biochemical oxygen demand between 200mg/L and 300mg/L, the optimal pretreatment conditions should reach: pH value 2-4, total dissolved solids can be 400mg/L-600mg/L , the ferrous ion concentration is 0.2mmol/L～0.4mmol/L.

When the present invention works, the sewage to be treated enters the water distribution pipe 12 at the bottom of the tower through the water inlet pipe 11, and enters the inner tower through the water distribution pipe 12. The compressed air reaches the aeration head 8 through the air supply pipe 7 to aerate the sewage. Driven by the aeration air, the sewage flows upward from the inner tower, and after reaching the top of the inner tower, it flows downward between the outer tower wall 1 and the inner tower wall 4 and returns to the bottom of the tower, forming an internal circulation flow. And under the action of the diversion hole 2, the internal circulation flow is further enhanced. During this process, the cathode 3 generates hydrogen peroxide through aeration, and at the same time, the surface of the cathode 3 reduces Fe ³⁺ to Fe ²⁺ , forming an electro-Fenton reaction zone near the cathode 3, causing the organic matter in the sewage to break or open. , and are rapidly oxidized and decomposed. At the same time, the anode 5 can also degrade part of the organic matter through electro-oxidation, so as to realize the treatment of the biorefractory organic wastewater in the present invention. The treated sewage is discharged from the outlet pipe 6 into a subsequent filtration or sedimentation treatment unit to achieve final purification of the sewage. The gas produced in the reaction process is discharged out of the tower through the exhaust valve 9 at the top of the tower.

In order to show that the present invention takes the treated iron filings as the effect of the cathode on sewage treatment, we use the graphite rod as the anode, and respectively use graphite, iron plate, and scrap iron filings as the cathode to investigate the electro-Fenton method of methyl orange solution by different cathodes. The effect of degradation. The experiment is as follows:

Reaction target solution volume: 750mL

Reaction target solution: methyl orange with a concentration of 0.05mmol·L ^-1

pH 3

The concentration of Na ₂ SO ₄ is 14.08mmol·L ^-1

The concentration of _FeSO4 is 0.27mmol L ^-1

Air velocity: 0.1m ³ /h

Tank voltage is 5V

Cathode electrode filling diameter: 60mm

Cathode electrode filling height: 300mm

Under the same conditions, the decolorization rate of methyl orange solution after taking electro-Fenton reaction treatment respectively is as shown in table 1:

Table 1 The decolorization rate of methyl orange solution degraded by different cathode materials

time (min) 5 10 20 30 graphite cathode 26.5% 42.5% 62.2% 76.6% iron plate cathode 37.8% 45.3% 68.7% 82.7% Iron filings cathode 55.5% 76.2% 92.4% 96.8%

It can be seen from the experimental results that using iron filings as the cathode, the electro-Fenton method for degrading the decolorized azo dyes has a better reaction effect than graphite and iron plates as the cathode.

On this basis, we also used different reactors to perform comparative experiments on the degradation of decolorized methyl orange solutions:

The reaction target solution volume is: 750mL

Reaction target solution: methyl orange with a concentration of 0.05mmol·L ^-1

pH 3

The concentration of Na ₂ SO ₄ is 14.08mmol·L ^-1

The concentration of _FeSO4 is 0.27mmol L ^-1

Air velocity: 0.1m ³ /h

Tank voltage is 5V

The cathode electrode filling diameter of the present invention: 60mm, the cathode electrode filling height: 300mm

Square reaction cell cathode plate area: 70cm ² , plate spacing 4cm

 Two different types of electric Fenton reactors were used to treat the same simulated wastewater. The decolorization rate of methyl orange solution after treatment is shown in Table 2.

Table 2 Comparison of decolorization rates of different forms of electro-Fenton reactors for degrading methyl orange solutions

Reactor form Tower reactor of the present invention square electrolytic cell Solution decolorization rate after 15min reaction 96.7% 61.2%

It can be seen from the above experiments that the electric Fenton tower reactor of the present invention has higher efficiency and shorter reaction time in degrading the decolorized azo dye methyl orange solution than the square electrolytic cell.

Meanwhile, we have also done the experiment that the present invention handles furfural production waste water:

The reaction target solution volume is: 750mL

Reaction target solution: furfural industrial wastewater filtered through qualitative filter paper,

The chemical oxygen demand COD is 8910～12610mg·L ^-1

pH value is 2.45~3.25

Dosing Na ₂ SO ₄ concentration is 80mg·L ^-1

Air velocity: 0.1m ³ /h

Tank voltage is 8V

Cathode electrode filling diameter: 60mm, cathode electrode filling height: 300mm

Adopt the reactor of the present invention to carry out the treatment of furfural production wastewater, the reaction residence time is 5 hours, after the treatment, add the NaOH solution that the mass concentration is 5% to adjust the pH value of the solution to be 9, then use qualitative filter paper to filter, the filtered solution COD The COD of furfural wastewater before treatment is shown in Table 3.

Table 3 utilizes the present invention to handle the comparison before and after the treatment of furfural production wastewater

Furfural wastewater COD Filtered wastewater COD treated by the present invention 8910~12610 mg·L ^-1 98 ~83mg·L ^-1

It can be clearly seen from this experiment that the COD of furfural production wastewater treated by the present invention has been greatly reduced, and the removal rate has reached 99%.

In order to further show the effect of the present invention on treating organic sewage, we have done the process of treating printing and dyeing wastewater

experiment of:

The reaction target solution volume is: 750mL

Reaction target solution: printing and dyeing wastewater from a hosiery factory filtered through qualitative filter paper,

The chemical oxygen demand COD is 1260～2140mg·L ^-1

The chromaticity is 650~1900 times

The pH value is 10.5~13.5

Add H ₂ SO ₄ solution with a mass concentration of 5% to adjust the pH value to 3

Dosing Na ₂ SO ₄ concentration is 100mg·L ^-1

Air velocity: 0.1m ³ /h

Tank voltage is 7V

Inner circulation cathode electrode filling diameter: 60mm, cathode electrode filling height: 300mm

Adopt the present invention to carry out the treatment of printing and dyeing wastewater, the reaction residence time is 3 hours, after the treatment, add the NaOH solution that the mass concentration is 5% to adjust the pH value of the solution to 9, then use qualitative filter paper to filter, the COD of the filtered solution is the same as that of the printing and dyeing before treatment See Table 4 for wastewater COD and its decolorization rate.

Table 4 Utilizes the present invention to process printing and dyeing wastewater situation

Printing and dyeing wastewater COD Filtered wastewater COD treated by the present invention Decolorization rate 1260～2140mg·L ^-1 86 ~72mg·L ^-1 95~98%

It can be seen from the experiment that the COD of printing and dyeing wastewater is greatly reduced after being treated by the equipment of the present invention, and the decolorization rate reaches 95%~98%. level standard.

In summary, the present invention has the advantages of small footprint, fast response, good treatment effect, high work efficiency, low operating cost, less investment and quick results. Compared with the prior art, it has outstanding substantive features and significant It is the most ideal organic sewage treatment equipment at present. It is suitable for application in various industries such as chemical industry, and has good development prospects and promotion value.

Claims (3)

1. specific equipment that utilizes electro-Fenton reaction to handle organic sewage, comprise dc power supply (10), water inlet pipe (11), rising pipe (6), vent valve (9), it is characterized in that: this equipment also comprises the tower reactor with inner tower wall (4) and the double-deck tower body of outer tower wall (1), iron filings negative electrode (3) in the inner tower wall (4), graphite-rod anode (5) between inner tower wall (4) and the outer tower wall (1), and the set aeration head of interior tower bottom (8) and water distributor (12), wherein said iron filings negative electrode (3) is that the waste iron filing that produces with metal processing is material, adopt 10% mass concentration dilute hydrochloric acid to clean and removed surface and oil contaminant in 20 minutes, be 6-8 with flushing with clean water to washing back water pH value again, then at its surface chemistry metal refining Ag or Ti, to form electric Fenton bimetal negative electrode, among the tower, bulk density was 2.0T/m in described negative electrode (3) was filled in ³～2.5T/m ³

2. the specific equipment that utilizes electro-Fenton reaction to handle organic sewage according to claim 1, it is characterized in that: described graphite rod diameter as anode (5) is 1cm～5cm, and number is 3～8, the interior tower outer wall 1cm～10cm of distance.

3. the specific equipment that utilizes electro-Fenton reaction to handle organic sewage according to claim 1, it is characterized in that: described inner tower wall (4) is provided with equally distributed pod apertures (2), and pod apertures (2) diameter is 1cm～5cm, and total percentage of open area is 10%～20%.

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