Photoelectrochemical treatment method and device

Abstract

The invention relates to a photoelectrochemical treatment method and device, and belongs to the technical field of petroleum and petrochemical sewage treatment and reuse, the treatment method comprises the following steps: carrying out flocculation pretreatment on sewage to obtain a supernatant; carrying out photoelectrochemical reaction on the supernate to obtain reacted sewage; and carrying out adsorption treatment on the reacted sewage to obtain discharged water. According to the treatment device disclosed by the invention, the gas-liquid filter screen is arranged, so that gas-liquid foam is prevented from overflowing and the influence on the reaction of an added medicament and sewage is avoided; the photoelectrochemical reactor adopts a tubular structure, so that the concentration of pollutants in the reactor can be kept uniform, and the reaction rate is stable without dead angles; the arrangement of the gas-liquid-foam extraction opening realizes the suction of gas-liquid foam, can timely dredge and discharge gases such as chlorine, oxygen and ammonia gas generated in oxidation reaction and foam generated by polymer reaction in sewage, keeps the pressure balance in the photoelectrochemical reactor, and avoids the influence of the gas-liquid foam on the full contact of the treatment liquid and the electrode plate at the same time.

Description

Technical Field

[0001] The invention belongs to the technical field of petroleum and petrochemical wastewater treatment and reuse, and in particular relates to a photoelectrochemical treatment method and device. Background Art

[0002] Under the "dual carbon" goal, in order to continuously promote the low-cost and efficient reuse and reinjection of waste liquid in the petroleum industry, it is necessary to break through the difficulties of efficient degumming and organic pollutant treatment of salt-containing and polymer-containing waste liquid. The composition of salt-containing and polymer-containing wastewater is complex. The additives in the original working fluid include more than a dozen types of thickeners, cross-linking agents, drag reducers, degumming agents, demulsifiers, high-temperature stabilizers, surfactants, etc. These substances have formed large molecular benzene series and aromatic compounds and higher fatty acids, aldehydes and ketones and other organic pollutants that are difficult to degrade after high temperature and high pressure during the operation process. Moreover, these organic polymer substances form highly stable emulsion colloids with suspended matter and oil droplets, and have strong interaction with oil substances. They are suspended in wastewater, resulting in high viscosity and difficulty in degumming and destabilization. In addition, the organic pollutants have high concentrations, high salinity, and poor biodegradability.

[0003] The processes aimed at destabilizing and degrading organic matter are mainly coagulation, filtration, ozonation, and electro-flocculation. In actual applications, a variety of treatment methods are usually applied in combination. In general, various waste liquid treatment technologies nowadays have their own unique characteristics, but these technologies are currently in operation in reality and there are still some shortcomings. On the one hand, the processes with low costs and simple processes have poor treatment effects, which affect the performance of reused liquid preparation or exceed the farmland irrigation standards. If reinjection is carried out, a large amount of suspended matter, scaling ions, etc. will be injected into the formation, which will cause great damage to the reservoir; on the other hand, the processes with better treatment effects have high treatment costs and complex processes, making it difficult to achieve industrial application. Therefore, both in terms of economy and treatment effect, further improvement and improvement are needed in the application. Summary of the invention

[0004] In view of the above problems, the present invention provides a photoelectrochemical processing method and device.

[0005] An object of the present invention is to provide a photoelectrochemical treatment method, the treatment method comprising:

[0006] The sewage is subjected to flocculation pretreatment to obtain a supernatant;

[0007] The supernatant is subjected to a photoelectrochemical reaction to obtain wastewater after the reaction;

[0008] The wastewater after the reaction is subjected to adsorption treatment to obtain drainage.

[0009] Furthermore, the flocculation pretreatment has a treatment time of 20-30 minutes.

[0010] Furthermore, the power of the ultraviolet lamp for the photoreaction in the photoelectrochemical reaction is 10-15w, and the irradiation intensity is 20-40μW / cm 2 .

[0011] Furthermore, the electrode working current density of the electrical reaction in the photoelectrochemical reaction is 10-25 mA / cm2, and the time is 60-120 min.

[0012] Furthermore, the chemical reaction in the photoelectrochemical reaction is an aeration reaction, the aeration gas is air or oxygen, and the gas-water volume ratio is 10:1-20:1.

[0013] Furthermore, the adsorption treatment adopts activated carbon adsorption, the size of the activated carbon is 200-400 mesh, the filling density is 15-20g / L, and the adsorption time is 30-60min.

[0014] The second object of the present invention is to provide a photoelectrochemical treatment device, the treatment device comprising a pretreatment tank, a photoelectrochemical reactor and an adsorption column, the first water outlet of the pretreatment tank is connected to the second water inlet of the photoelectrochemical reactor, and the second water outlet of the photoelectrochemical reactor is connected to the third water inlet of the adsorption column;

[0015] The pretreatment tank is used to perform flocculation pretreatment on sewage to obtain a supernatant;

[0016] The photoelectrochemical reactor is used to perform a photoelectrochemical reaction on the supernatant to obtain post-reaction wastewater;

[0017] The adsorption column is used to perform adsorption treatment on the wastewater after the reaction to obtain drainage.

[0018] Furthermore, the photoelectrochemical reactor is a tubular structure, a partition is provided in the inner tank of the photoelectrochemical reactor, the partition divides the inner tank of the photoelectrochemical reactor into a reaction zone and a clean water zone, an overflow port is provided above the partition, and the reaction zone and the clean water zone are connected through the overflow port;

[0019] The second water inlet is arranged at the bottom of the reaction zone, and an electrode plate and an ultraviolet lamp are arranged in the reaction zone. The electrode plate is parallel to the wall of the photoelectrochemical reactor, and the height of the electrode plate is lower than the height of the partition. The ultraviolet lamp is parallel to the electrode plate and is located at the axis of the photoelectrochemical reactor. An aeration port is arranged at the bottom of the reaction zone away from the second water inlet, and the second water outlet is arranged on the bottom wall of the clean water zone.

[0020] Furthermore, the volume ratio of the reaction zone to the clean water zone is 4:1-5:1.

[0021] Furthermore, a gas-liquid-foam suction port is provided on the top of the reaction zone, and the gas-liquid-foam suction port is connected to the first water inlet of the pretreatment tank through a pipeline, and a switch and a peristaltic pump are provided on the pipeline.

[0022] Furthermore, the distance between the electrode plate and the ultraviolet lamp tube is 0.5-1.0 cm.

[0023] Furthermore, the electrode plates include a plurality of anode plates and cathode plates arranged in pairs, the anode plates are adjacent to the ultraviolet lamp tubes, the anode plates are made of iron plates or metal oxide plates, and the cathode plates are made of titanium plates.

[0024] Beneficial effects of the present invention:

[0025] The gas-liquid filter is set to avoid gas-liquid foam overflow and the impact on the reaction between the added chemicals and sewage;

[0026] The photoelectrochemical reactor adopts a tubular structure, which can maintain uniform pollutant concentration in the reactor, stable reaction rate and no dead angle; the gas-liquid-foam suction port is set to realize the suction of gas-liquid-foam, and can timely guide and remove gases such as chlorine, oxygen and ammonia generated in the oxidation reaction, as well as foam generated by the polymer reaction in the sewage, to maintain the pressure balance in the photoelectrochemical reactor, and at the same time avoid the gas-liquid-foam from affecting the full contact between the treatment liquid and the electrode plate;

[0027] Through the combination of different types of anode plates, the effective removal of ammonia nitrogen and organic matter can be achieved under a wider range of pH conditions, reducing the plate consumption and water inlet conditions. Under acidic conditions, the divalent iron ions generated by the iron electrode through electrolysis can react with the H2O2 generated by the reduction of aerated oxygen at the cathode to generate hydroxyl radicals, thereby increasing the concentration of oxidizing substances. The trivalent iron ions generated during the reaction obtain electrons again at the cathode and are reduced to divalent iron ions, thus realizing the recycling of iron ions, thereby reducing the consumption of iron plates, power consumption and the generation of iron sludge. The metal oxide plate makes it easier for the chloride ions in the sewage to discharge and generate active chlorine (Cl2, HOCl, ClO - The active chlorine reacts with ammonia nitrogen to remove nitrogen and promote the oxidation efficiency of other organic matter. Under alkaline conditions, the divalent iron ions generated by the electrolysis of the iron electrode react with OH - The highly active flocculating groups of iron are generated to adsorb and co-precipitate pollutants; ammonia nitrogen can exist in the form of free NH3, which is adsorbed on the surface of the metal oxide anode plate and undergoes a three-electron transfer reaction with the anode to be oxidized and removed;

[0028] Ultraviolet rays promote the production of active substances by different types of anode plates and chloride ions, thus improving the oxidation efficiency. The ultraviolet lamp is placed between two anode plates. For iron anode plates, the divalent iron ions produced by anode electrolysis and the hydroxide ions produced by cathode water electrolysis generate iron complexes, such as Fe(OH) 2+ ,Fe(ROH)2+ , which can generate free radicals under the action of ultraviolet rays, accelerating the decomposition rate of organic matter; for metal oxide plates, when the anode undergoes an oxygen evolution side reaction, some organic matter will be excited by 254nm ultraviolet light to become active substances, which react with oxygen, and the active oxygen molecules formed by electron transfer further react with water to generate hydrogen peroxide and dissolved oxygen, thereby achieving full utilization of the oxygen in the side reaction to degrade organic matter. When pH <= 7, ultraviolet light can also activate chloride ions and generate active chlorine (Cl·) and hydroxyl radicals at the same time, improving the degradation effect of organic matter.

[0029] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 A flow chart of a photoelectrochemical processing method according to an embodiment of the present invention is shown;

[0032] Figure 2 A schematic diagram of a photoelectrochemical processing device according to an embodiment of the present invention is shown;

[0033] In the figure:

[0034] 10. Pretreatment tank; 11. Gas-liquid filter; 12. Dosing pipeline; 13. Agitator; 14. First water inlet; 15. Mud outlet; 16. First water outlet; 20. Photoelectrochemical reactor; 21. Second water inlet; 22. Reaction zone; 23. Aeration outlet; 24. Electrode plate; 25. Second water outlet; 26. Clean water zone; 27. Partition; 28. Overflow outlet; 29. ​​Gas-liquid-foam extraction outlet; 30. Adsorption column. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] like Figure 1 As shown, a photoelectrochemical treatment method according to an embodiment of the present invention comprises:

[0037] The sewage is subjected to flocculation pretreatment to obtain a supernatant;

[0038] The supernatant is subjected to a photoelectrochemical reaction to obtain wastewater after the reaction;

[0039] The wastewater after the reaction is subjected to adsorption treatment to obtain drainage.

[0040] In an embodiment of the present invention, the treatment time of the flocculation pretreatment is 20-30 min, and the treatment time of the flocculation pretreatment is specifically any one of 20 min, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27 min, 28 min, 29 min, and 30 min.

[0041] In an embodiment of the present invention, if the suspended matter content is high in the flocculation pretreatment, a flocculant (30% PAC) and a coagulant aid (cationic PAM) are added, and the pH is adjusted to 8 to separate the suspended matter in the water; if the calcium and magnesium ions or sulfate ions are high, lime milk, sodium carbonate and a flocculant are added to control the pH to be no higher than 10, reduce the ion concentration and hardness, and control the effluent hardness to below 1000 mg / L and the sulfate ion to below 2000 mg / L; if the suspended matter and nitrogen compounds are low and only the organic matter content is high, the pH is adjusted to about 4 by an acid-base regulator (NaOH, HCl).

[0042] In the embodiment of the present invention, the power of the ultraviolet lamp for the photoreaction in the photoelectrochemical reaction is 10-15W, specifically, the power value is any one of 10W, 11W, 12W, 13W, 14W, and 15W, and the irradiation intensity is 20-40μW / cm 2 Specifically, the auxiliary light value is 20μW / cm 2 , 25μW / cm 2 、30μW / cm 2 、35μW / cm 2 , 40μW / cm 2 Any one of .

[0043] In the embodiment of the present invention, the electrode working current density of the electrical reaction in the photoelectrochemical reaction is 10-25 mA / cm 2 Specifically, the value of the electrode working current density is 10 mA / cm 2 , 13mA / cm 2 , 15mA / cm 2 , 16mA / cm 2 , 18mA / cm 2 , 20mA / cm 2 , 23mA / cm 2 , 25mA / cm 2 The working time is 60-120 min. Specifically, the working time is any one of 60 min, 70 min, 80 min, 90 min, 100 min, 110 min, and 120 min.

[0044] In an embodiment of the present invention, the chemical reaction in the photoelectrochemical reaction is an aeration reaction, the aeration gas is air or oxygen, and the gas-water volume ratio is 10:1-20:1. Specifically, the gas-water ratio is any one of 10:1, 12:1, 13:1, 14:1, 15:1, 16:1, 17:1, 18:1, 19:1, and 20:1.

[0045] In an embodiment of the present invention, the adsorption treatment adopts activated carbon adsorption, and the size of the activated carbon is 200-400 mesh, specifically, the size value of the activated carbon is any one of 200 mesh, 210 mesh, 220 mesh, 230 mesh, 250 mesh, 300 mesh, 320 mesh, 350 mesh, 370 mesh, 380 mesh, and 400 mesh, and the filling density is 15-20g / L, specifically, the specific value of the filling density is any one of 15g / L, 16g / L, 17g / L, 18g / L, 19g / L, and 20g / L, and the adsorption time is 30-60min, specifically, the specific value of the adsorption time is any one of 30min, 35min, 40min, 45min, 50min, 55min, and 60min.

[0046] like Figure 2 As shown, a photoelectrochemical processing device according to an embodiment of the present invention comprises:

[0047] A photoelectrochemical processing device according to an embodiment of the present invention comprises:

[0048] It includes a pretreatment tank 10, a photoelectrochemical reactor 20 and an adsorption column 30, wherein the first water outlet 16 of the pretreatment tank 10 is connected to the second water inlet 21 of the photoelectrochemical reactor 20, and the second water outlet 25 of the photoelectrochemical reactor 20 is connected to the third water inlet of the adsorption column 30;

[0049] The pretreatment tank 10 is used to perform flocculation pretreatment on the sewage to obtain a supernatant;

[0050] The photoelectrochemical reactor 20 is used to perform a photoelectrochemical reaction on the supernatant to obtain the post-reaction wastewater;

[0051] The adsorption column 30 is used to perform adsorption treatment on the wastewater after the reaction to obtain drainage.

[0052] In this embodiment, the first water outlet 16 is arranged on the upper side of the peripheral wall of the pretreatment tank 10, and a dosing pipeline 12 is arranged on the upper side of the peripheral wall of the pretreatment tank 10 away from the first water outlet 16. The dosing pipeline 12 is used for adding agents such as flocculants, coagulants, lime milk, sodium carbonate, pH regulators, etc. in the flocculation treatment, so as to facilitate the flocculation and hardness removal treatment operations and realize the partial ion removal function of the pretreatment tank 10;

[0053] The pretreatment tank 10 is provided with a stirring paddle 13, and the stirring paddle 13 is connected to a motor, and the motor is arranged at the top of the pretreatment tank 10, and the output end of the motor passes through the top outer wall of the pretreatment tank 10 and is connected to the stirring paddle 13, and the motor drives the stirring paddle 13 to rotate, thereby realizing the stirring of sewage and flocculant, coagulant, lime milk, sodium carbonate, and pH adjuster in the pretreatment tank 10, and realizing the homogenization and pH adjustment functions of the pretreatment tank 10;

[0054] During the treatment of sewage in the pretreatment tank 10, if a reagent that can produce precipitation is added, the stirring paddle 13 performs intermittent operation, the cycle of the intermittent operation is consistent with the treatment time of the flocculation pretreatment, and the stop time is ensured to be 10 minutes to allow the sludge to settle and discharge;

[0055] The pretreatment tank 10 is provided with a gas-liquid filter 11, which is located at the cross section of the pretreatment tank 10. The top of the stirring paddle 13 passes through the gas-liquid filter 11 and extends to the bottom of the pretreatment tank 10. The stirring paddle 13 is rotatably connected to the gas-liquid filter 11. The arrangement of the gas-liquid filter 11 facilitates the removal of suspended matter in the pretreatment tank 10.

[0056] The bottom of the pretreatment tank 10 is provided with a mud discharge port 15 .

[0057] In the embodiment of the present invention, the photoelectrochemical reactor 20 is a tubular structure, and a partition 27 is provided in the inner tank of the photoelectrochemical reactor 20. The partition 27 divides the inner tank of the photoelectrochemical reactor 20 into a reaction zone 22 and a clean water zone 26. An overflow port 28 is provided above the partition 27, and the reaction zone 22 and the clean water zone 26 are connected through the overflow port 28;

[0058] The second water inlet 21 is arranged on the bottom wall of the reaction zone 22, and an electrode plate 24 and an ultraviolet lamp are arranged in the reaction zone 22. The electrode plate 24 is parallel to the wall of the photoelectrochemical reactor 20, and the height of the electrode plate 24 is lower than the height of the partition 27. The water flow direction is parallel to the electrode plate 24, and the ultraviolet lamp is parallel to the electrode plate 24 and is located at the axis of the photoelectrochemical reactor 20. An aeration port 23 is arranged on the bottom wall of the reaction zone 22 away from the second water inlet 21;

[0059] The second water outlet 25 is arranged on the bottom wall of the clean water area 26;

[0060] The volume ratio of the reaction zone 22 and the clear water zone 26 is 4:1-5:1, specifically, the volume ratio is any one of 4:1, 4.2:1, 4.5:1, 4.8:1, and 5:1;

[0061] The electrode plate 24 includes a plurality of anode plates and cathode plates arranged in pairs, the anode plates are adjacent to the ultraviolet lamp tube, the anode plates are made of iron plates or metal oxide plates (including titanium-based ruthenium-iridium-coated plates, titanium-based iridium-tantalum-coated plates), and the cathode plates are made of titanium plates;

[0062] The distance between the anode plate and the cathode plate is 0.5-1.0 cm, and the specific distance is any one of 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, and 1.0 cm. The number of groups of the electrode plates 24 is 4 or 7, the number of the ultraviolet lamp tubes is 1 or 2, and the plates of the same polarity are connected in parallel. The electrode plate 24 is a flat plate.

[0063] The distance between the electrode plate 24 (anode plate) and the ultraviolet lamp is 0.5-1.0 cm;

[0064] The photoelectrochemical reactor 20 is made of light-proof PVC material and placed horizontally, with both ends fully enclosed and only the power connector left. A transparent observation window is set on the side wall to confirm the liquid level, and the window has a push-pull light-shielding plate.

[0065] In certain embodiments of the present invention, a gas-liquid foam extraction port 29 is provided on the top of the reaction zone 22, and the gas-liquid foam extraction port 29 is connected to the first water inlet 14 of the pretreatment tank 10 through a pipeline. A switch and a peristaltic pump are provided on the pipeline to facilitate the extraction of the gas-liquid foam generated in the photoelectrochemical reactor 20 and discharge it into the pretreatment tank 10 for flocculation pretreatment again.

[0066] In an embodiment of the present invention, the adsorption column 30 is filled with activated carbon adsorption, the size of the activated carbon is 200-400 mesh, specifically, the size value of the activated carbon is any one of 200 mesh, 210 mesh, 220 mesh, 230 mesh, 250 mesh, 300 mesh, 320 mesh, 350 mesh, 370 mesh, 380 mesh, and 400 mesh, the filling density is 15-20 g / L, specifically, the specific value of the filling density is any one of 15 g / L, 16 g / L, 17 g / L, 18 g / L, 19 g / L, and 20 g / L, the adsorption time is 30-60 min, specifically, the specific value of the adsorption time is any one of 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, and 60 min;

[0067] The third water inlet is disposed at the top of the adsorption column 30 , and the bottom of the adsorption column 30 is provided with a third water outlet for discharging the treated drainage.

[0068] The processing principle of the photoelectrochemical processing device is:

[0069] In an embodiment of the present invention, the sewage enters the pretreatment tank 10 through the first water inlet 14, and the flocculant and / or coagulant aid and / or lime milk and / or sodium carbonate and / or pH adjuster enters the pretreatment tank 10 through the dosing pipeline 12, and then is evenly mixed with the sewage under the action of the stirring paddle 13, flocculation occurs, and supernatant and sludge are obtained, wherein the sludge is discharged from the sludge discharge port 15, so as to achieve homogenization of the sewage, pH adjustment, removal of some ions and suspended matter, provide suitable pH conditions for subsequent photoelectrochemical reactions, and avoid ions causing pollution and scaling of subsequent units;

[0070] The supernatant passes through the first water outlet 16 and the second water inlet 21, and enters the reaction zone 22 of the photoelectrochemical reactor 20, and simultaneously undergoes light reaction, electric reaction and chemical reaction under the action of the electrode plate 24, the ultraviolet lamp tube and the aeration port 23, so as to realize the strong oxidation function of the photoelectrochemical reactor 20 and remove organic pollutants and ammonia nitrogen. The supernatant passes through the photoelectrochemical reaction in the reaction zone 22, and flows into the clean water zone 26 through the overflow port 28 to obtain the wastewater after the reaction, and the COD of the wastewater after the reaction can reach 150-200 mg / L, the ammonia nitrogen is 0-10 mg / L, and the pH is 6-8;

[0071] The post-reaction sewage enters the adsorption column 30 from the second water outlet 25 and the third water inlet, and is adsorbed by activated carbon to achieve deep removal of organic pollutants to obtain drainage, which is discharged from the third drainage port, and the COD of the drainage can reach below 100 mg / L.

[0072] Example 1

[0073] The device used to treat the salt-containing and nitrogen-containing sewage in area A is the above-mentioned photoelectrochemical treatment device, such as Figure 2 As shown, the ratio of the reaction zone 22 and the clean water zone 26 of the photoelectrochemical reactor 20 is 4:1, with a total of 4 sets of electrode plates 24, wherein the anodes are respectively an iron plate and a titanium-based ruthenium-iridium plate, the cathode plate is a titanium plate, and there is 1 ultraviolet lamp; the distance between the anode plate and the cathode plate is 0.5 cm, and the distance between the anode plate and the ultraviolet lamp is 1 cm;

[0074] The quality of raw sewage before treatment was pH=7.8, hardness 800mg / L, chloride ion 6800mg / L, COD 1140mg / L, kinematic viscosity 1.2939m2 / s, ammonia nitrogen 225mg / L, and total nitrogen 425mg / L.

[0075] Photoelectrochemical reaction treatment method:

[0076] The raw sewage was pumped into the pretreatment tank 10, the pH was adjusted to 4, and after stirring for 10 minutes, a supernatant was obtained;

[0077] The supernatant is pumped into the photoelectrochemical reactor 20 through the first water outlet 16 and the second water inlet 21, using a constant current mode with a current intensity of 20 mA / cm 2 , UV lamp power 15w, irradiation intensity 40μW / cm 2, air aeration is adopted, the air-water volume ratio is 10:1, and the residence time (i.e., the working time) is 90 minutes; the sewage in the reaction zone 22 overflows to the clean water zone 26 through the overflow port 28 above the partition 27, and enters the activated carbon adsorption column 30 through the second water outlet 25, and the gas-liquid foam generated in the reaction zone 22 is sucked by a peristaltic pump and connected to the first water inlet 14 of the pretreatment tank 10 to return to the pretreatment tank 10;

[0078] The powdered activated carbon of the activated carbon adsorption column 30 has a size of 300 meshes, a filling density of 20 g / L, an adsorption time of 30 minutes, and the effluent is the final drainage.

[0079] The drainage parameters obtained were pH=6.8, COD 88mg / L, no ammonia nitrogen detected, and total nitrogen 25mg / L. The water quality met the farmland irrigation standards.

[0080] Embodiment 2:

[0081] To treat the high-salt and high-ammonia nitrogen wastewater in area B, the device used is the above-mentioned photoelectrochemical treatment device, such as Figure 2 As shown, the ratio of the reaction zone 22 and the clean water zone 26 of the photoelectrochemical reactor 20 is 5:1, with a total of 4 groups of electrode plates 24, wherein the anode is a titanium-based iridium-tantalum plate coated with an anode, the cathode plate is a titanium plate, and there is 1 ultraviolet lamp; the spacing between the anode plate and the cathode plate is 1 cm, and the spacing between the anode plate and the ultraviolet lamp is 0.5 cm.

[0082] The water quality of the raw sewage before treatment was pH=8.2, suspended solids 430mg / L, hardness 1200mg / L, chloride ion 10390mg / L, COD 870mg / L, ammonia nitrogen 980mg / L, and total nitrogen 1733mg / L.

[0083] Photoelectrochemical reaction treatment method:

[0084] The raw sewage was pumped into the pretreatment tank 10, the pH was adjusted to 9, PAC 1500 mg / L, PAM 10 mg / L were added, stirred for 10 minutes, and allowed to stand for 10 minutes to obtain the supernatant;

[0085] The supernatant is pumped into the photoelectrochemical reactor 20 through the first water outlet 16 and the second water inlet 21, using a constant current mode with a current intensity of 25 mA / cm 2 , UV lamp power 10w, irradiation intensity 20μW / cm 2 , air aeration is adopted, the air-water ratio is 20:1, and the residence time is 60min; the sewage in the reaction zone 22 overflows to the clean water zone 26 through the overflow port 28 above the partition 27, and enters the activated carbon adsorption column 30 through the second water outlet 25; the gas-liquid foam generated in the reaction zone 22 is sucked by a peristaltic pump, connected to the first water inlet 14 of the pretreatment tank 10 and returns to the pretreatment tank 10;

[0086] The powdered activated carbon of the activated carbon adsorption column 30 has a size of 400 mesh, a filling density of 15 g / L, an adsorption time of 60 minutes, and the effluent is the final drainage.

[0087] The drainage parameters obtained were PH=7, COD 77mg / L, ammonia nitrogen not detected, and total nitrogen 42mg / L.

[0088] Embodiment 3:

[0089] The device used to treat the saline and nitrogen-containing sewage in area C is the above-mentioned photoelectrochemical treatment device, such as Figure 2 As shown, the ratio of the reaction zone 22 and the clear water zone 26 of the photoelectrochemical reactor 20 is 5:1, with a total of 7 sets of electrode plates 24, wherein the anode is an iron plate, a titanium-based ruthenium-iridium plate, and a titanium-based iridium-tantalum plate, and the cathode plate is a titanium plate, and there are 2 ultraviolet lamps; the plates and lamps are arranged as follows: titanium plate, ruthenium-iridium-titanium plate, ultraviolet lamp, iron plate, titanium plate, iron plate, ultraviolet lamp, iridium-tantalum-titanium plate, and titanium plate. The spacing between the anode plate and the cathode plate is 0.5 cm, and the spacing between the anode plate and the ultraviolet lamp is 1 cm.

[0090] The quality of raw sewage before treatment was pH=6.88, hardness 1000mg / L, sulfate ion 5950mg / L, chloride ion 13800mg / L, COD 1248mg / L, ammonia nitrogen 735mg / L, and total nitrogen 1652mg / L.

[0091] The raw sewage is pumped into the pretreatment tank 10, and 3300 mg / L of lime milk, 2200 mg / L of sodium carbonate, 1000 mg / L of PAC, and 10 mg / L of PAM flocculants are added to the pretreatment tank 10 from the dosing pipeline 12, and the pH is controlled to be 10, stirred for 15 minutes, and after standing for 15 minutes, the sulfate ion is 1830 mg / L, the hardness is 850 mg / L, and a supernatant is obtained;

[0092] The supernatant was pumped into the photoelectrochemical reactor 20 in a constant current mode with a current intensity of 10 mA / cm 2 , UV lamp power 10w, irradiation intensity 20μW / cm 2 , air aeration is adopted, the air-water ratio is 15:1, and the residence time is 120min; the sewage in the reaction zone 22 overflows to the clean water zone 26 through the overflow port 28 above the partition 27, and enters the activated carbon adsorption column 30 through the second water outlet 25; the gas-liquid foam generated in the reaction zone 22 is sucked by a peristaltic pump, connected to the first water inlet 14 of the pretreatment tank 10 and returned to the pretreatment tank 10;

[0093] The size of the powdered activated carbon in the activated carbon adsorption column 30 is 200 mesh, the filling density is 20 g / L, the adsorption time is 60 minutes, and the effluent is the final drainage.

[0094] The drainage parameters obtained were PH=7.8, COD 98mg / L, ammonia nitrogen not detected, and total nitrogen 40mg.

[0095] Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent substitutions for some of the technical features therein; and these modifications or substitutions do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photoelectrochemical treatment method, characterized in that: include: The sewage is subjected to flocculation pretreatment to obtain a supernatant; The supernatant is subjected to a photoelectrochemical reaction to obtain wastewater after the reaction; The wastewater after the reaction is subjected to adsorption treatment to obtain drainage.

2. The photoelectrochemical treatment method according to claim 1, characterized in that: The treatment time of the flocculation pretreatment is 20-30 minutes.

3. The photoelectrochemical treatment method according to claim 1, characterized in that: The power of the ultraviolet lamp for the photoreaction in the photoelectrochemical reaction is 10-15w, and the irradiation intensity is 20-40μW / cm 2 .

4. The photoelectrochemical treatment method according to claim 1, characterized in that: The electrode working current density of the electrical reaction in the photoelectrochemical reaction is 10-25 mA / cm 2 , time is 60-120min.

5. The photoelectrochemical treatment method according to claim 1, characterized in that: The chemical reaction in the photoelectrochemical reaction is an aeration reaction, the aeration gas is air or oxygen, and the gas-to-water volume ratio is 10:1-20:

1.

6. The photoelectrochemical treatment method according to any one of claims 1 to 5, characterized in that: The adsorption treatment adopts activated carbon adsorption, the size of the activated carbon is 200-400 mesh, the filling density is 15-20g / L, and the adsorption time is 30-60min.

7. A photoelectrochemical treatment device, characterized in that: The invention comprises a pretreatment tank (10), a photoelectrochemical reactor (20) and an adsorption column (30), wherein a first water outlet (16) of the pretreatment tank (10) is connected to a second water inlet (21) of the photoelectrochemical reactor (20), and a second water outlet (25) of the photoelectrochemical reactor (20) is connected to a third water inlet of the adsorption column (30); the pretreatment tank (10) is used for flocculation pretreatment of sewage to obtain a supernatant; The photoelectrochemical reactor (20) is used to perform a photoelectrochemical reaction on the supernatant to obtain post-reaction wastewater; The adsorption column (30) is used to perform adsorption treatment on the wastewater after the reaction to obtain drainage.

8. The photoelectrochemical processing device according to claim 7, characterized in that: The photoelectrochemical reactor (20) is of a tubular structure. A partition (27) is provided in the inner tank of the photoelectrochemical reactor (20). The partition (27) divides the inner tank of the photoelectrochemical reactor (20) into a reaction zone (22) and a clean water zone (26). An overflow port (28) is provided above the partition (27). The reaction zone (22) and the clean water zone (26) are connected via the overflow port (28). The second water inlet (21) is arranged at the bottom of the reaction zone (22); an electrode plate (24) and an ultraviolet lamp are arranged in the reaction zone (22); the electrode plate (24) is parallel to the wall of the photoelectrochemical reactor (20); the height of the electrode plate (24) is lower than the height of the partition (27); the ultraviolet lamp is parallel to the electrode plate (24) and is located at the axis of the photoelectrochemical reactor (20); an aeration port (23) is arranged at the bottom of the reaction zone (22) away from the second water inlet (21); and the second water outlet (25) is arranged on the bottom wall of the clean water zone (26).

9. The photoelectrochemical processing device according to claim 8, characterized in that: The volume ratio of the reaction zone (22) to the clean water zone (26) is 4:1-5:

1.

10. The photoelectrochemical processing device according to claim 8, characterized in that: A gas-liquid-foam suction port (29) is provided on the top of the reaction zone (22), and the gas-liquid-foam suction port (29) is connected to the first water inlet (14) of the pretreatment tank (10) through a pipeline, and a switch and a peristaltic pump are provided on the pipeline.

11. The photoelectrochemical processing device according to claim 8, characterized in that: The distance between the electrode plate (24) and the ultraviolet lamp tube is 0.5-1.0 cm.

12. The photoelectrochemical treatment device according to any one of claims 8 to 10, characterized in that: The electrode plates (24) include a plurality of anode plates and cathode plates arranged in pairs, the anode plates are adjacent to the ultraviolet lamp tubes, the anode plates are made of iron plates or metal oxide plates, and the cathode plates are made of titanium plates.

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