CN111186898B - Method and device for treating printing and dyeing wastewater through Fenton oxidation by taking scrap iron as iron source - Google Patents

Abstract

The invention discloses a method and a device for treating printing and dyeing wastewater by Fenton oxidation with scrap iron as an iron source. The device comprises a pH adjusting tank and Fe which are connected in sequence²⁺The system comprises a dissolving-out tower, a Fenton oxidation tower and a sedimentation tank; wherein, the upper part of the pH adjusting tank is connected with a water inlet pipe a and an acid medicine tank; fe²⁺The dissolving-out tower is provided with a perforated plate, a lower supporting layer, an upper supporting layer and an iron scrap filling layer in sequence from the lower part to the middle part of the tower body; the upper part of the tower body is provided with an air storage tank which is communicated with the inside of the tower body through an air duct; h is connected to the Fenton oxidation tower₂O₂The upper part of the medicine tank is provided with a water outlet pipe which is connected with the sedimentation tank; the water inlet pipe b and the water outlet pipe of the Fenton oxidation tower are arranged at the same horizontal position; the sedimentation tank is connected with an alkali liquor tank, the upper part of the sedimentation tank is provided with a purified water outlet pipe, and the lower part of the sedimentation tank is provided with a sludge pipe. The invention realizes Fe through scrap iron²⁺The continuous input of the water is realized, and the continuous treatment process of a large amount of wastewater is met; the iron simple substance existing in the solution can effectively avoid Fe²⁺Is oxidized into Fe³⁺(ii) a The generated hydrogen is recycled as energy.

Description

A method and device for treating printing and dyeing wastewater by Fenton oxidation using iron filings as iron source

technical field

The invention relates to a method and a device for treating printing and dyeing wastewater by Fenton oxidation using iron filings as an iron source, and belongs to the technical field of wastewater treatment.

Background technique

The textile industry is a traditional pillar industry in my country, and textile printing and dyeing is one of the key industries for industrial pollution prevention and water saving. Printing and dyeing is the post-processing process of textile products, and it is also the most polluting process in the textile industry. At present, my country's printing and dyeing enterprises mainly use the wet processing technology with water as the medium. This type of method requires a large amount of water in the production process, and discharges a large amount of organic wastewater with high chroma and high pollution. According to statistics, the national printing and dyeing wastewater discharge amount is 3×10 ⁶ ～ 4×10 ⁶ m ³ /d, which has become a major industrial wastewater discharger. 10% of the total amount of wastewater; accounting for 60% to 80% of the total wastewater discharge from the textile industry. For a large amount of printing and dyeing wastewater, it is also a huge challenge to properly treat it and meet the discharge standards.

Advanced oxidation processes (AOPs) have received extensive attention because they have shown great potential for the treatment of high-concentration, refractory organic wastewater. It mainly includes O ₃ oxidation method, photocatalytic oxidation method, electrochemical oxidation method and Fenton oxidation method. Among them, the advanced oxidation process of Fenton reagent has received extensive attention due to its wide application range, mild reaction conditions, simple operation, and rapid degradation and mineralization. However, in the actual treatment process of printing and dyeing wastewater, FeSO ₄ needs to be continuously added and a large amount of iron sludge will be generated after the reaction, resulting in secondary pollution, which is not conducive to the continuous treatment of large amounts of wastewater.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a method and device for treating printing and dyeing wastewater by Fenton oxidation with iron filings as an iron source.

The invention provides a device for treating printing and dyeing wastewater by Fenton oxidation using iron filings as an iron source, comprising a pH adjustment tank, a Fe ²⁺ dissolution tower, a Fenton oxidation tower and a sedimentation tank connected in sequence;

The upper part of the pH adjustment tank is connected with a water inlet pipe a and an acid medicine tank, and the lower part is provided with a water outlet;

The Fe ²⁺ dissolution tower includes three parts: the lower part, the middle part and the upper part of the tower body; the lower part of the tower body is provided with an inlet to connect with the water outlet of the pH adjustment tank; along the direction from the lower part of the tower body to the middle part, the tower body is A perforated plate, a lower support layer, an upper support layer and an iron filing filling layer are arranged in the lower part of the body in sequence; the middle part of the tower body is provided with a water outlet to connect with the inlet pipe b of the upper inlet of the Fenton oxidation tower; The upper part of the body is provided with an air storage tank, which is communicated with the inside of the tower body through an air guide pipe;

The Fenton oxidation tower is connected with a H ₂ O ₂ medicine tank, and its upper part is provided with a water outlet pipe to be connected with the sedimentation tank; the water inlet pipe b of the Fenton oxidation tower and the water outlet pipe are arranged in the same horizontal position;

The settling tank is connected with an alkaline liquid medicine tank, the upper part is provided with a purified water outlet pipe, and the lower part is provided with a sludge pipe.

In the present invention, the Fe ²⁺ stripping tower includes three parts: the lower part, the middle part and the upper part of the tower body; the details are as follows: the lower part of the Fe ²⁺ stripping tower body is specifically an area of H=100cm, Φ=10cm; the Fe ²⁺ The middle part of the stripping tower body is specifically the area of H=10cm, Φ=20cm; the upper part of the Fe ²⁺ stripping tower body is specifically the hemispherical area of SΦ20cm;

The lower part of the tower body is composed of a perforated plate, a double glass column support layer and an iron filing layer. The wastewater after pH adjustment enters from the bottom of the tower body and flows from bottom to top. By controlling the contact time with the iron filings, the purpose of controlling the Fe ²⁺ concentration in the wastewater is achieved;

The middle part of the tower body is provided with a drainage outlet, and its function is that Fe ²⁺ is continuously dissolved in the lower part of the tower body, and by further mixing in the middle part of the tower body, it is ensured that the Fe ²⁺ concentration in the drainage is uniform and meets the requirements;

The upper part of the tower body is provided with a gas storage tank, which is used to recover the H ₂ generated in the process of processing, and use it as clean energy to avoid waste of resources.

In the present invention, the flushing of the outlet pipe of the Fenton oxidation tower with the inlet pipe mainly has the following three functions:

First, the flow direction of the wastewater is bottom-up, and the water outlet is set up at a higher position, which can promote the mixing of the solution more uniformly, so as to achieve a full reaction and ensure the removal of pollutants;

Second, the water outlet pipe b is arranged on the upper part of the Fenton oxidation tower, which can improve the treatment capacity of waste water, which is conducive to the continuous treatment of waste water (assuming that the water outlet is set up at the Fenton oxidation tower at 30cm or 110cm from the ground, if you want to To achieve the same residence time, the lower the drain position, the slower the flow rate of wastewater, and the less wastewater treatment volume per unit time);

Third, from the perspective of space, the water inlet pipe and the water outlet pipe are at the same height, which is more beautiful.

In the above-mentioned device, the acid medicine tank is connected to the water inlet pipe a;

A pipeline mixer is provided on the water inlet pipe a between the acid medicine tank and the pH adjustment tank.

In the above-mentioned device, the acid medicine in the acid medicine tank is pumped into the pH adjustment tank by the water pump a;

The effluent of the pH adjustment tank is pumped into the Fe ^dissolution tower by another water pump a;

A water pump b is provided on the connecting pipeline between the water outlet of the Fe ²⁺ dissolution tower and the Fenton oxidation tower;

The H ₂ O ₂ in the H ₂ O ₂ medicine tank is pumped into the Fe ²⁺ dissolution tower through the water pump c;

Another described water pump c is provided on the connecting pipeline between the Fenton oxidation tower and the sedimentation tank;

The lye in the lye medicine tank is pumped into the sedimentation tank by the water pump d;

The sludge pipe is provided with another said water pump d.

In the above-mentioned device, each is provided with a stirring paddle in the pH adjustment tank and the Fenton oxidation tower;

The pH adjustment tank, the Fe ²⁺ dissolution tower and the sedimentation tank are each provided with a pH detector, and they are respectively located at the water outlet of the pH adjustment tank and the water outlet of the Fe ²⁺ dissolution tower. and the middle and lower part of the sedimentation tank.

In the above device, both the lower support layer and the upper support layer are glass bead support layers, and the glass bead particle size of the lower support layer is larger than the glass bead particle size of the upper support layer;

The water inlet pipe is made of 304 type stainless steel;

The acid medicine tank is lined with phenolic resin;

The water pump a adopts CN-7M or alloy 20 type water pump, and its connecting pipeline is made of 304 type stainless steel;

The pH adjustment tank is made of carbon steel for anti-corrosion;

The material of the tower body of the Fe ²⁺ dissolution tower adopts glass fiber reinforced plastic;

The material of the gas storage tank is carbon steel;

The water pump b is made of non-metallic material, and the pipeline connected to it is made of polyvinyl chloride or chlorinated polyvinyl chloride;

The H ₂ O ₂ medicine tank is made of aluminum alloy 5254 or 316L stainless steel;

The water pump c is made of type 316 stainless steel or PTFE, and the conveying pipeline connected to it is made of type 316L stainless steel;

The Fenton reaction tower body is made of 316L stainless steel;

The material of the lye pot is FRP;

The water pump d is made of stainless steel or carbon steel, and the conveying pipeline connected to it is made of CPVC or FRP;

The sedimentation tank is made of carbon steel;

The material of the sludge pipe and the purified water outlet pipe is CPVC or FRP.

In the present invention, the selection of materials for each part of the device for the Fenton oxidation treatment of printing and dyeing wastewater with iron filings as the iron source is in accordance with the "Urban Sewage Treatment Plant Operation Management Manual Volume 1 Management and Configuration System" (6th edition, 2013 ) in the preparation of relevant regulations for the storage and transportation of chemical agents.

In the present invention, the height ratio of the double glass support layer (4mm glass bead support layer and 2mm glass bead support layer) is 1:1; the height of the single support layer is between 10 and 15cm; the height of the double glass support layer and the iron filing layer is between And control in ≤50cm. In the embodiment, the upper layer is a 4mm glass bead support layer 12 with a height of 10cm and a 2mm glass bead support layer 13 with a height of 10cm, and the height of the iron filing layer 14 is 10cm.

The present invention also provides a method for treating printing and dyeing wastewater by Fenton oxidation using iron filings as an iron source by using the above-mentioned device, comprising the following steps: 1) the printing and dyeing wastewater enters the pH adjustment tank through the water inlet pipe a, and the acid agent The acid solution in the tank is added to the pH adjustment tank to adjust the pH value of the outlet water of the pH adjustment tank;

2) The effluent from the pH adjustment tank enters the Fe ²⁺ stripping tower, contacts and reacts with the iron filings filling layer, so that the Fe ²⁺ dissolves into the waste water, and the generated gas is collected in the gas storage tank through the air guide pipe ;

3) The printing and dyeing wastewater treated by the Fe ²⁺ stripping tower enters the Fenton oxidation tower through the water outlet, while H ₂ O ₂ enters the Fenton oxidation tower from the H ₂ O ₂ medicine tank through pipelines Oxidation reaction with wastewater;

4) The waste water after being treated by the Fenton oxidation tower enters the sedimentation tank, and the lye in the lye pot is added to the sedimentation tank to adjust the pH value of the waste water. The purified water is discharged from the water outlet pipe, and the sludge at the bottom is discharged from the sludge pipe.

In the above-mentioned method, the acid solution is H ₂ SO ₄ solution;

In step 1), the pH detector is used to detect the pH value of the outlet water of the pH adjustment tank, and the pH value of the outlet water of the pH adjustment tank is adjusted to 2±0.2;

When the printing and dyeing wastewater is adjusted in the pH adjustment tank, the stirring paddle is used for advanced stirring.

In the above-mentioned method, the pH value of the printing and dyeing wastewater treated by the Fe ²⁺ stripping tower in step 2) is monitored at the outlet, and when the pH value is greater than 2+0.2, the pH adjustment is increased. The dosage of the acid solution in the pool is such that the pH value of the water discharged from the drain outlet is 2±0.2.

In the above method, the waste water in the Fenton oxidation tower is stirred by the stirring paddle to carry out the oxidation reaction.

In the above method, the alkaline solution is NaOH solution, and in step 4), the pH value of the wastewater is adjusted to 7±0.2.

The present invention has the following advantages:

(1) The continuous treatment of wastewater is realized. By replacing FeSO ₄ with iron filings, the continuous input of Fe ²⁺ can be realized to meet the continuous treatment process of a large amount of wastewater; and the outlet pipe of the Fenton oxidation tower is flush with the inlet pipe, It can promote the mixing of the solution to be more uniform, so that the reaction can be fully carried out, the removal effect of pollutants can be ensured, the treatment capacity of wastewater can be increased, and the continuous treatment of wastewater can be facilitated.

(2) The elemental iron existing in the solution can effectively prevent Fe ²⁺ from being oxidized to Fe ³⁺ and improve the efficiency of the Fenton reaction.

(3) The gas (H ₂ ) produced in the reaction process enters the gas storage chamber through the gas pipe, and can be used as energy.

Description of drawings

1 is a schematic structural diagram of a device for treating printing and dyeing wastewater by Fenton oxidation using iron filings as an iron source according to the present invention.

The marks in the figure are as follows:

1 is the water inlet pipe a; 2 is the acid medicine tank; 3 is the water pump a; 4 is the pipeline mixer; 51, 52 are the stirring paddles; 61, 62, 63 are the pH detectors; 91 is Fe ²⁺ stripping tower; 92 is Fenton oxidation tower; 10 is gas storage tank, 11 is gas guide pipe; 12 is lower support layer; 13 is upper support layer; 14 is iron filing filling layer; 15 is H ₂ O ₂ medicine tank; 16 is the lye medicine tank; 17 is the sedimentation tank; 18 is the sludge pipe; 19 is the purified water outlet pipe; 20 is the water pump b; 21 is the water pump c; 22 is the water pump d.

Detailed ways

The experimental methods used in the following examples are conventional methods unless otherwise specified.

The materials, reagents, etc. used in the following examples can be obtained from commercial sources unless otherwise specified.

In the following examples, 1, experimental water

Using malachite green chloride to simulate printing and dyeing wastewater, the preparation method of the stock solution is as follows: accurately weigh 1.04g of malachite green chloride powder and dissolve it in water, and then dilute to a 1L volumetric flask with a concentration of 1000mg/L;

Polyvinyl alcohol (PVA) is used to simulate desizing wastewater. The preparation method of the stock solution is as follows: accurately weigh 0.5 g of polyvinyl alcohol dried at 105-110 °C to a constant weight, add an appropriate amount of distilled water, heat to dissolve, and cool down. Dilute to 1L to prepare 500mg/L PVA stock solution;

2. Experimental reagents

Sodium hydroxide (NaOH), analytical purity 99%, purchased from Xilong Chemical Co., Ltd.; sulfuric acid (H ₂ SO ₄ ), analytical purity 98%, purchased from Beijing Chemical Factory; iron powder, analytical purity 98%, 400 mesh , purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; hydrogen peroxide (H ₂ O ₂ ), analytically pure mass fraction of 30%, substance concentration of 9.79 mol/L, purchased from Xilong Chemical Co., Ltd.; Malachite Green Chloride Compound (C ₂₃ H ₂₅ ClN ₂ ), analytical purity 96%, purchased from Tianjin Fuchen Chemical Reagent Co., Ltd.; reduced iron powder, analytical purity 98%, 400 mesh, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. Polyvinyl alcohol (PVA) 1799, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; boric acid, analytically pure 99%, purchased from Tianjin Fuchen Chemical Reagent Co., Ltd. The preparation method is as follows: Weigh 40g of boric acid and dissolve it in 1L High-purity water; iodine element, analytical purity 99.8%, potassium iodide, analytical purity 99%, both purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. The preparation method of the solution is as follows: take 0.65g of iodine and 2.5g of potassium iodide, dissolve in high-purity water, and then Dilute to 100mL to obtain iodine-potassium iodide solution.

Embodiment 1, the Fenton oxidation treatment device of printing and dyeing wastewater with iron filings as iron source

Figure 1 is a schematic structural diagram of a device for treating printing and dyeing wastewater by Fenton oxidation using iron filings as an iron source according to the present invention.

The design parameters of each component are as follows: the water inlet pipe a 1 is made of 304 type stainless steel (acid-proof); the acid tank 2 is made of phenolic resin lined steel with a design size of Φ20×20cm, and the water pump a 3 is made of CN-7M (alloy 20). Type water pump, the pipeline where the pump a 3 is located is made of 304 stainless steel; the size of the pH adjustment tank 7 is 50 × 50 × 50cm, and it is made of carbon steel for anti-corrosion; the main material of the Fe ²⁺ dissolution tower 91 is glass fiber reinforced plastic (FRP), The tower body is divided into 3 parts, the lower part of the tower is H=100cm, Φ=10cm, the upper layer of the perforated plate 8 is the lower support layer 12 of 4mm glass beads with a height of 10cm and the upper support layer 13 of 2mm glass beads with a height of 10cm, filled with iron filings The layer 14 is 10 cm high and the contact time is determined according to the desired Fe ²⁺ concentration. The middle part of Fe ²⁺ dissolution tower 91 is H=10cm, Φ=20cm, and the water outlet is in the middle. The upper part of the Fe ²⁺ stripping tower 91 is the H ₂ gas storage tank 10, the material is carbon steel, and the size ^is a hemisphere of SΦ20cm; Polyvinyl chloride (CPVC), the water pump b 20 is made of non-metallic material; the H ₂ O ₂ medicine tank 15 is made of aluminum alloy 5254 or 316L type stainless steel, the design size is Φ20×20cm, the water pump c 21 is made of 316 type stainless steel or PTFE Ethylene material, conveying pipeline is 316L stainless steel; Fenton oxidation tower 92 is made of 316L stainless steel, and the design size is the same as that of Fe ²⁺ stripping tower 91, but there is no H ₂ gas storage tank. The residence time in the Fenton oxidation tower 92 is determined according to the treated wastewater; the lye tank 16 is made of FRP, the design size is Φ20×20cm, the water pump d 22 is made of stainless steel or carbon steel, and the conveying pipeline is made of CPVC or FRP; the sedimentation tank 17 is made of carbon steel with a size of 50×50×50cm; the sludge pipe 18 and the purified water outlet pipe 19 are made of CPVC or FRP.

The structure and process of the whole device are as follows: the printing and dyeing wastewater enters the pH adjustment tank 7 after mixing with the acid (H ₂ SO ₄ ) output from the acid medicine tank 2 through the water inlet pipe a 1 . The pH adjustment tank 7 is provided with a stirring paddle 51 and a pH detector 61 . The pH detector 61 is located at the water outlet of the pH adjustment tank 7 to ensure that the pH is between 2±0.2. The stirring paddle 51 is located at the center of the pH adjustment tank 7 . The functions of the pH detector 61 and the stirring paddle 51 are to control the dosage of H ₂ SO ₄ and to ensure uniform mixing of the solution. A water inlet pipe a1 is arranged on the upper left of the pH adjustment tank 7, and a water outlet pipe is arranged on the lower right side, and the water outlet pipe is connected with the water pump a3. The effluent from pH adjustment tank 7 enters Fe ²⁺ stripping tower 91 through water pump a 3 . The Fe ²⁺ dissolution tower 91 is composed of three parts: the lower part, the middle part and the upper part of the tower body; the lower part of the tower body is provided with an inlet to connect with the water outlet of the pH adjustment tank 7; The perforated plate 8 for supporting, the lower support layer 12 of 4mm glass beads, the upper support layer 13 of 2mm glass beads and the iron filing layer 14 (the iron filings are filled evenly); The water inlet pipe b of the upper inlet is connected; the upper part of the tower body is provided with a gas storage tank 10, which is communicated with the inside of the tower body through the air guide pipe 11; the strong acid waste water is in contact with the iron filings, so that Fe ²⁺ dissolves into the waste water, and obtains continuous Replenish. The gas storage tank 10 is arranged on the upper part of the Fe ²⁺ dissolution tower 91 , and the gas (H ₂ ) generated during the reaction enters the gas storage tank 10 through the gas conduit 11 . The gas (H ₂ ) produced during the reaction is collected into the gas storage tank 10 and reused as an energy source. The Fe ²⁺ dissolution tower 91 is also provided with a pH detector 62 . The pH detector 62 is set at the water outlet. If the pH is greater than 2+0.2, the dosage of H ₂ SO ₄ in the pH adjustment tank 7 should be increased in time to avoid the hydrolysis of Fe ²⁺ . The water inlet pipe b of the Fe ²⁺ dissolution tower 91 is arranged at the bottom of the tower, the water outlet pipe is arranged below the gas storage tank 10 , and the water outlet pipe is connected with the water pump b 20 . The effluent of Fe ²⁺ dissolution tower 91 enters Fenton oxidation tower 92 through water pump b20. H ₂ O ₂ enters the Fenton oxidation tower 92 from the H ₂ O ₂ medicine tank 15 through the medicine adding pipeline. A stirring paddle 52 is also provided in the Fenton oxidation tower 92 . The stirring paddle 52 is arranged near the bottom of the Fenton oxidation tower 92 for uniform mixing of the waste water. The water inlet pipe b of the Fenton oxidation tower 92 is flush with the water outlet pipe of the Fe ²⁺ dissolution tower 91 . The outlet pipe of Fenton oxidation tower 92 is flush with the inlet pipe b, and the outlet pipe is connected to the water pump. The effluent from the Fenton oxidation tower 92 enters the sedimentation tank 17 through the water pump c 21 . The effluent and lye from the Fenton oxidation tower 92 enter the sedimentation tank 17 . A pH detector 63 is installed in the sedimentation tank 17 . The pH detector 63 is located in the lower part of the middle of the sedimentation tank 17, so that pH=7±0.2 to ensure drainage. The function of the pH detector 63 is to control the dosage of the lye solution. A purified water outlet pipe 19 is arranged at the upper right of the sedimentation tank 17, and a sludge pipe 18 is arranged at the bottom and is connected to the water pump d 22.

Embodiment 2,

experimental method:

Waste water enters through the water inlet pipe 1 . Start the centrifugal pump, extract the H ₂ SO ₄ in the acid medicine tank 2, enter the pH adjustment tank through the pipeline mixer 4, turn on the stirring paddle 5, and adjust the H ₂ SO ₄ input amount in real time according to the pH detector 6 to ensure the pH stability of the wastewater Early 2 ± 0.2. The waste water in the conditioning tank enters the Fe ²⁺ dissolution tower 9 through a centrifugal pump. At this time, the generated H ₂ enters the gas storage tank 10 through the gas conduit 11, and the contact time between the waste water and the iron filing layer is determined according to the experimental conditions. The waste water mixed with Fe ²⁺ enters the Fenton reaction tower 9 through the centrifugal pump, and the H ₂ O ₂ solution is added from the H ₂ O ₂ medicine tank, and the stirring paddle 5 is turned on. The residence time is determined by experiments according to the quality of the waste water. After the reaction, the wastewater enters the sedimentation tank 17, and NaOH solution is added simultaneously, and the amount of NaOH added is regulated in real time according to the pH detector 6. After staying in the sedimentation tank 17 for 30 minutes, the sludge is removed by the sludge pipe 18 , and the upper-layer purified water is discharged from the purified water outlet pipe 19 .

Analysis test method:

The detection method of malachite green is as follows: measure the absorbance of the treated wastewater (Shimadzu, UV-1800) at a wavelength of 618 nm, and bring the absorbance into the standard curve to obtain the concentration of the remaining malachite green.

The detection method of PVA is as follows: suck 25 mL of the sample to be tested into a colorimetric tube, add 15 mL of boric acid solution and 2.00 mL of iodine-potassium iodide solution in turn, and then dilute with high-purity water to the mark, shake well to obtain a blue-green solution. After standing for 10 min, the absorbance was measured at a wavelength of 680 nm (Shimadzu, UV-1800). The concentration of PVA was obtained by plugging the absorbance into the standard curve.

The results and discussion of the above experiments:

The concentration of the wastewater containing malachite green is 200mg/L, and the experimental parameters are as follows: add H ₂ SO ₄ (1mol/L) in the adjustment tank, the dosage is 5mL/L, and the pH of the wastewater is adjusted to 2.0±0.2; H ₂ The dosage of O ₂ (30%) is 1mL/L; the contact time of waste water and iron filings in the Fe ²⁺ dissolution tower is controlled to be 5min, and the Fe ²⁺ dissolution concentration is 5±0.3mmol/L at this time; n(H ₂ O ₂ ): n(Fe ^{2 +} )=1.9～2.1; the residence time in the Fenton reaction tower is 10min; the effluent enters the sedimentation tank, the dosage of NaOH solution (1mol/L) is 3mL/L, and the pH is controlled at 7± 0.2, the residence time is 30min. In the final effluent, the removal of malachite green is 100%.

The concentration of the wastewater containing PVA is 200mg/L, and the experimental parameters are as follows: add H ₂ SO ₄ (1mol/L) in the adjustment tank, the dosage is 5mL/L, and the pH of the wastewater is adjusted to 2.0±0.2; H ₂ O ₂ (30%) dosage is 1mL/L; control the contact time of waste water and iron filings in Fe ²⁺ dissolution tower to be 5min, at this time Fe ²⁺ dissolution concentration is 5±0.3mmol/L; n(H ₂ O ₂ ): n(Fe ^{2 +} )=1.9～2.1; the residence time in the Fenton reaction tower is 30min; the effluent enters the sedimentation tank, the dosage of NaOH solution (1mol/L) is 3mL/L, and the pH is controlled at 7±0.2 , the residence time is 30 min. In the final effluent, the removal effect of PVA is 100%.

Claims (10)

1. A device for Fenton oxidation treatment of printing and dyeing wastewater by taking scrap iron as an iron source comprises a pH adjusting tank and Fe which are sequentially connected²⁺The system comprises a dissolving-out tower, a Fenton oxidation tower and a sedimentation tank;

the upper part of the pH adjusting tank is connected with a water inlet pipe a and an acid medicine tank, and the lower part of the pH adjusting tank is provided with a water outlet;

said Fe²⁺The digestion tower comprises a tower body, a lower part, a middle part and an upper part; the lower part of the tower body is provided with an inlet which is connected with a water outlet of the pH adjusting tank; a perforated plate, a lower supporting layer, an upper supporting layer and an iron scrap filling layer are sequentially arranged in the lower part of the tower body along the direction from the lower part to the middle part of the tower body; a water outlet is formed in the middle of the tower body and connected with a water inlet pipe b of an inlet at the upper part of the Fenton oxidation tower; the upper part of the tower body is provided with an air storage tank which is communicated with the inside of the tower body through an air duct;

h is connected to the Fenton oxidation tower₂O₂The top of the medicine tank is provided with a water outlet pipe which is connected with the sedimentation tank; the water inlet pipe b of the Fenton oxidation tower and the water outlet pipe are arranged at the same horizontal position;

the sedimentation tank is connected with an alkali liquor tank, the upper part of the sedimentation tank is provided with a purified water outlet pipe, and the lower part of the sedimentation tank is provided with a sludge pipe.

2. The apparatus of claim 1, wherein: the acid medicine tank is connected to the water inlet pipe a;

and a pipeline mixer is arranged on the water inlet pipe a between the acid medicine tank and the pH adjusting tank.

3. The apparatus of claim 1 or 2, wherein: acid medicine in the acid medicine tank is pumped into the pH adjusting tank through a water pump a;

the effluent of the pH adjusting tank is pumped into the Fe through another water pump a²⁺Dissolving out of the tower;

said Fe²⁺A water pump b is arranged on a connecting pipeline between a water outlet of the dissolution tower and the Fenton oxidation tower;

said H₂O₂H in the medicine tank₂O₂Pumping in the Fe by a water pump c²⁺Dissolving out of the tower;

the other water pump c is arranged on a connecting pipeline between the Fenton oxidation tower and the sedimentation tank;

pumping the alkali liquor in the alkali liquor tank into the sedimentation tank through a water pump d;

the sludge pipe is provided with another water pump d.

4. The apparatus of claim 1 or 2, wherein: a stirring paddle is arranged in each of the pH adjusting tank and the Fenton oxidation tower;

the pH adjusting tank and the Fe²⁺A pH detector is respectively arranged in the dissolution tower and the sedimentation tank and is respectively positioned at the water outlet of the pH adjusting tank and the Fe²⁺A water outlet of the dissolution tower and the middle-lower part of the sedimentation tank.

5. The apparatus of claim 3, wherein: the lower supporting layer and the upper supporting layer are glass bead supporting layers, and the particle size of glass beads of the lower supporting layer is larger than that of glass beads of the upper supporting layer;

the water inlet pipe is made of 304 type stainless steel;

the acid medicine tank is made of lining steel of phenolic resin;

the water pump a is a CN-7M or alloy 20 type water pump, and a connecting pipeline of the water pump a is made of 304 type stainless steel;

the pH adjusting tank adopts carbon steel for corrosion prevention;

said Fe²⁺The material of the body of the dissolution tower is glass fiber reinforced plastic;

the material of the gas storage tank is carbon steel;

the water pump b is made of a non-metal material, and a pipeline connected with the water pump b is made of polyvinyl chloride or chlorinated polyvinyl chloride;

said H₂O₂The medicine tank is made of aluminum alloy 5254 or 316L type stainless steel;

the water pump c is made of 316-type stainless steel or polytetrafluoroethylene, and a conveying pipeline connected with the water pump c is made of 316L-type stainless steel;

the Fenton oxidation tower body is made of 316L stainless steel;

the alkali liquor tank is made of FRP;

the water pump d is made of stainless steel or carbon steel, and a conveying pipeline connected with the water pump d is made of CPVC or FRP;

the sedimentation tank is made of carbon steel;

the sludge pipe and the purified water outlet pipe are made of CPVC or FRP.

6. A method for treating printing and dyeing wastewater by Fenton oxidation with scrap iron as an iron source by using the device of claim 4, comprising the following steps: 1) printing and dyeing wastewater enters the pH adjusting tank through the water inlet pipe a, acid liquor in the acid medicine tank is added into the pH adjusting tank, and the pH value of effluent at the water outlet of the pH adjusting tank is adjusted;

2) the effluent of the pH adjusting tank enters the Fe²⁺The dissolution tower is in contact reaction with the iron scrap filling layer to ensure that Fe²⁺Dissolving out the waste water, and collecting the generated gas in the gas storage tank through the gas guide pipe;

3) said Fe²⁺The printing and dyeing wastewater treated by the dissolution tower enters the Fenton oxidation tower through the water outlet, and H simultaneously₂O₂From said H₂O₂The medicine tank enters the Fenton oxidation tower through a pipeline to perform oxidation reaction with the wastewater;

4) and the wastewater treated by the Fenton oxidation tower enters the sedimentation tank, alkali liquor in the alkali liquor tank is added into the sedimentation tank to adjust the pH value of the wastewater, purified water at the upper layer in the sedimentation tank is discharged from the purified water outlet pipe, and sludge at the bottom is discharged from the sludge pipe.

7. The method of claim 6, wherein: the acid liquor is H₂SO₄A solution;

in the step 1), the pH value of the effluent of the water outlet of the pH adjusting tank is detected by the pH detector, and the pH value of the effluent of the water outlet of the pH adjusting tank is adjusted to 2 +/-0.2;

and when the printing and dyeing wastewater is regulated in the pH regulating tank, the stirring paddle is adopted for stirring.

8. The method according to claim 6 or 7, characterized in that: in step 2) with said Fe²⁺Monitoring the pH value of the printing and dyeing wastewater treated by the dissolution tower at the water discharge port, and when the pH value is reached>When the pH value is 2+0.2, increasing the adding amount of the acid liquor in the pH adjusting pool so as to enable the pH value of the water discharged from the water outlet to be 2 +/-0.2.

9. The method according to claim 6 or 7, characterized in that: and the Fenton oxidation tower is used for stirring the wastewater by the stirring paddle to perform oxidation reaction.

10. The method according to claim 6 or 7, characterized in that: the alkali liquor is NaOH solution, and the pH value of the wastewater is adjusted to 7 +/-0.2 in the step 4).

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