High-salinity oil-containing wastewater treatment system and method by coupling photovoltaic-assisted electric flocculation with solar interface evaporation

Abstract

The invention relates to a system and a method for treating high-salinity oily wastewater by coupling photovoltaic-assisted electric flocculation with solar interface evaporation. The system consists of a photovoltaic power generation assembly, an electric flocculation assembly and a solar interface evaporation assembly, the photovoltaic power generation assembly is used for converting solar energy into electric energy and storing the electric energy in the storage battery; the electric flocculation component is used for carrying out flocculation and air floatation treatment on the high-salinity oily wastewater through an electric flocculation process by utilizing the stored electric energy so as to remove organic matters and part of salt in the wastewater; the solar interface evaporator utilizes solar energy to evaporate water in the wastewater, and meanwhile, salt in the wastewater is greatly reduced, and organic matters are further removed. According to the method, clean energy is provided through photovoltaic power generation, and the high-salinity oily wastewater is effectively treated by combining an electric flocculation technology and an interface evaporation technology. The treated water quality can reach the drinking water standard of the World Health Organization, and the method has the advantages of low operation cost, high treatment efficiency, small environmental influence and the like, and has important application value and wide market prospect in treatment of high-salinity oil-containing wastewater and other difficult-to-treat wastewater.

Description

Technical Field

[0001] The invention relates to the technical field of high-salinity oily wastewater treatment, and in particular to a high-salinity oily wastewater treatment system and method using photovoltaic-assisted electric flocculation coupled with solar interfacial evaporation. Background Art

[0002] In the treatment of high-salinity oily wastewater, the operating steps of traditional technologies are usually "pretreatment + post-treatment + evaporation and crystallization". Although it can achieve a certain degree of wastewater treatment and resource utilization, it has problems such as high energy consumption, high cost, and low efficiency. In particular, these methods may produce secondary pollution during the treatment process, and it is difficult to completely remove organic matter and salt in the wastewater. In response to this challenge, researchers have been exploring more efficient, environmentally friendly and economical treatment technologies.

[0003] Solar interfacial evaporation technology is considered a promising technology that can replace traditional evaporation processes because of its green, environmentally friendly and sustainable characteristics. Chinese patent CN114873677B discloses a solar thermal water treatment method and device that is resistant to salt deposition. The device uses GO and two-dimensional metal carbonitrides to construct high-performance thermal conversion film materials, enhance thermal conversion performance, degrade organic matter, and achieve the removal of VOCs in water vapor. However, the efficiency of this technology in removing organic matter from water is not ideal, and the enrichment of organic matter may affect the crystallization of salt and reduce the quality of condensed water.

[0004] As an efficient oily wastewater treatment technology, electrocoagulation (EC) can effectively reduce the concentration of organic matter in wastewater and has the advantages of low energy consumption, low sludge production, and wide applicability. Chinese patent CN216863881U discloses a low-voltage electrocoagulation oxidation reaction device for laboratory wastewater, which is powered by solar panels and does not require access to the mains, saving energy and being green and environmentally friendly. However, it is difficult for either EC technology or solar interface evaporation technology alone to fully solve the problem of treating high-salinity oily wastewater.

[0005] Therefore, the present invention provides a system and method for treating high-salinity oily wastewater by photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation. This method uses the green electricity generated by the photovoltaic power generation system to drive the electro-flocculation process, effectively removing oil and part of the salt in the wastewater; then, the solar-driven interfacial evaporation technology is used to further remove residual organic matter and significantly reduce the salt content in the wastewater. This method can not only effectively treat high-salinity oily wastewater and meet the drinking water standards specified by the World Health Organization, but also has the advantages of low operating costs and green environmental protection. It has important application prospects in treating difficult-to-treat wastewater such as high-salinity oily wastewater. Summary of the invention

[0006] The purpose of the present invention is to provide a photovoltaic-assisted electro-flocculation coupled with solar interface evaporation high-salinity oily wastewater treatment system and method for the deficiencies in the prior art, the system is composed of a photovoltaic power generation component, an electro-flocculation component and a solar interface evaporation component; the photovoltaic power generation component includes a solar panel and a battery, which is used to convert solar energy into electrical energy and store it in the battery; the electro-flocculation component includes a DC power supply, a stirrer, an electro-flocculation reactor, waste aluminum cans, a metal mesh and a conductor, the component uses the stored electrical energy to flocculate and flotate the high-salinity oily wastewater through the electro-flocculation process to remove organic matter and part of the salt in the wastewater; the solar interface evaporator includes a photothermal layer, an insulation layer, a water storage tank, a condenser and a fresh water collector, the evaporator uses solar energy to evaporate the water in the wastewater, while greatly reducing the salt in the wastewater, and further removing organic matter. The method of the present invention provides clean energy through photovoltaic power generation, combines electro-flocculation and interface evaporation technology, and realizes the effective treatment of high-salinity oily wastewater. The quality of the treated water can meet the drinking water standards of the World Health Organization. It has the advantages of low operating cost, high treatment efficiency and small environmental impact. It has important application value and broad market prospects for treating difficult-to-treat wastewater such as high-salt oily wastewater.

[0007] The invention discloses a high-salinity oily wastewater treatment system that uses photovoltaic-assisted electro-flocculation coupled with solar interface evaporation. The system comprises a photovoltaic power generation component, an electro-flocculation component and a solar interface evaporation component. The photovoltaic power generation component comprises a solar cell panel (1) connected to a storage battery (2) for converting solar energy into electric energy and storing it. The electro-flocculation component comprises a direct current power supply (3), an agitator (4), an electro-flocculation reactor (5), waste aluminum cans (6), a metal mesh (7) and a conductor (8). The direct current power supply (3) and the agitator (4) are connected to the storage battery (2) via a cable. The electro-flocculation reactor (5) is provided with an anode waste aluminum can (6) and a cathode metal mesh (7), and the waste aluminum can (6) and the metal mesh (7) are connected to a DC power supply (3) via a wire (8); the solar interface evaporation component is composed of a photothermal layer (9), a heat insulation layer (10), a water storage tank (11), a condenser (12) and a fresh water collector (13); the photothermal layer (9) and the heat insulation layer (10) are placed on the water storage tank (11), the condenser (12) is covered above the water storage tank (11), and a fresh water collector (13) is provided at the bottom of the water storage tank (12).

[0008] In the electrocoagulation component of the system, the flocculation voltage is 10-20V, the electrocoagulation time is 10-30min, the distance between the cathode and the anode is 1-2.5cm, the electrocoagulation reactor (5) is made of acrylic glass, and the metal mesh (7) is made of stainless steel mesh or titanium mesh.

[0009] In the solar interface evaporation component of the system, the photothermal layer (9) is prepared by depositing 0.3wt% of carbon black and 0.02wt% of carbon dots on basalt fabric, the thermal insulation layer (10) is made of polystyrene material, the water storage tank (11) is made of acrylic glass, the condenser (12) is used to condense the water vapor generated by the photothermal layer (9) into droplets, and the fresh water collector (13) is used to collect the droplets generated by the condenser (12).

[0010] The method involved in the photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation high-salinity oily wastewater treatment system is carried out according to the following steps:

[0011] a. The solar panel (1) converts solar energy into electrical energy and stores it in the battery (2) for subsequent use;

[0012] b. The electric energy stored in the battery (2) is used to power the electro-flocculation component, the DC power supply (3) provides a stable voltage input for the electro-flocculation reaction, and the agitator (4) is used to maintain uniform mixing of the wastewater in the electro-flocculation reactor (5). The electro-flocculation reactor (5) is equipped with an anode of waste aluminum cans (6), a cathode metal mesh (7) and high-salinity oily wastewater. The anode and the cathode are connected to the DC power supply (3) through a wire (8) to form a closed circuit. Under the action of the electric field, the high-salinity oily wastewater is electrolyzed in the electro-flocculation reactor (5). The aluminum at the anode dissolves and generates aluminum ions during the electrolysis process. The aluminum ions react with hydroxide in the water to generate aluminum hydroxide flocs, which can adsorb and precipitate salt and oil droplets in the wastewater to achieve solid-liquid separation.

[0013] c. After the electrocoagulation reaction is completed, the water in the electrocoagulation reactor (5) flows into the water storage tank (11) through the pipeline, and the water in the water storage tank (11) is transported to the photothermal layer (9) by capillary action. The photothermal layer (9) captures sunlight to increase the temperature at the solid-liquid interface to generate water vapor that rises to the condenser (12), condenses into droplets when it is cold, and then drips into the fresh water collector (13) under the action of gravity.

[0014] The photovoltaic-assisted electro-flocculation coupled solar interfacial evaporation high-salinity oily wastewater treatment system and method described in the present invention are used to treat high-salinity oily wastewater and other difficult-to-treat wastewater.

[0015] The advantages of the present invention compared to the prior art are:

[0016] (1) The present invention uses green and clean solar energy as energy, which reduces dependence on traditional fossil energy, reduces greenhouse gas emissions, and meets the requirements of green environmental protection and sustainable development;

[0017] (2) The present invention can effectively remove organic matter and salt from high-salinity oily wastewater by coupling photovoltaic-assisted electrocoagulation with solar interfacial evaporation technology, thereby achieving efficient treatment and resource recovery of wastewater;

[0018] (3) The operating cost of the present invention is relatively low, mainly relying on the photovoltaic power generation system and solar interface evaporation, reducing the demand for external electricity, reducing operating costs, and having good economic benefits;

[0019] (4) The present invention is not only applicable to the treatment of high-salinity oily wastewater, but can also be applied to other difficult-to-treat wastewater, and has broad market application prospects and important environmental value. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic structural diagram of the photovoltaic-assisted electro-flocculation-solar interface evaporation coupling system of the present invention;

[0021] Figure 2 To simulate the COD concentration changes of high-salinity oily wastewater before treatment, after electrocoagulation, and after solar interfacial evaporation;

[0022] Figure 3 To simulate the changes in four typical ion concentrations of high-salinity oily wastewater before treatment, after electrocoagulation, and after solar interfacial evaporation.

[0023] Labels in the figure: 1-solar panel, 2-battery, 3-DC power supply, 4-agitator, 5-electrocoagulation reactor, 6-waste aluminum cans, 7-metal mesh, 8-wire, 9-photothermal layer, 10-insulation layer, 11-water storage tank, 12-condenser, 13-fresh water collector. DETAILED DESCRIPTION

[0024] In order to make those skilled in the art more clearly understand the technical solution of the present invention, the present invention will be clearly and completely described in conjunction with the embodiments. However, these embodiments do not limit the scope of the present invention. These only represent some embodiments of the present invention and do not cover all possible implementation methods. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work also belong to the protection scope of the present invention.

[0025] It should be noted that the experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials used can be purchased on the market unless otherwise specified.

[0026] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments:

[0027] Preparation of high-salinity oily wastewater

[0028] Take 24.500 g of sodium chloride, 5.200 g of magnesium chloride, 4.090 g of sodium sulfate, 1.160 g of calcium chloride, 0.695 g of potassium chloride, 0.201 g of potassium bicarbonate, 0.101 g of potassium bromide, 0.027 g of boric acid, 0.025 g of strontium chloride and 0.003 g of sodium fluoride and dissolve them in 980 mL of ultrapure water. Stir at 1500 rpm for 1 h to completely dissolve the salt in the water. Then add 0.5 g of Tween-80, 10 mL of benzene and 10 mL of toluene, and stir continuously at 1500 rpm for 12 h.

[0029] Example 1

[0030] The invention discloses a photovoltaic-assisted electro-flocculation coupled solar interface evaporation system for treating high-salinity oily wastewater. The system comprises a photovoltaic power generation component, an electro-flocculation component and a solar interface evaporation component. The photovoltaic power generation component comprises a solar panel 1 connected to a battery 2, and is used to convert solar energy into electrical energy and store it. The electro-flocculation component comprises a DC power supply 3, an agitator 4, an electro-flocculation reactor 5, waste aluminum cans 6, a metal mesh 7 and a conductor 8. The DC power supply 3 and the agitator 4 are connected to the battery 2 via a cable. Anode waste aluminum cans 6 and cathode metal mesh 7 are placed inside the electro-flocculation reactor 5. The waste aluminum cans 6 and the metal mesh 7 are connected to the DC power supply 3 via the conductor 8. The solar interface evaporation component comprises a photothermal layer 9, a heat insulation layer 10, a water storage tank 11, a condenser 12 and a fresh water collector 13. The photothermal layer 9 and the heat insulation layer 10 are placed on the water storage tank 11. The condenser 12 is covered above the water storage tank 11. A fresh water collector 13 is provided at the bottom of the water storage tank 12.

[0031] The flocculation voltage in the electro-flocculation component of the system is 10V, the electro-flocculation time is 30min, the distance between the cathode and the anode is 1cm, the electro-flocculation reactor 5 is made of acrylic glass, and the metal mesh 7 is made of stainless steel mesh or titanium mesh;

[0032] In the solar interface evaporation component of the system, the photothermal layer 9 is made of 0.3wt% carbon black and 0.02wt% carbon dots deposited on basalt fabric, the thermal insulation layer 10 is made of polystyrene material, the water storage tank 11 is made of acrylic glass, the condenser 12 is used to condense the water vapor generated by the photothermal layer 9 into droplets, and the fresh water collector 13 is used to collect the droplets generated by the condenser 12;

[0033] The method involved in the photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation high-salinity oily wastewater treatment system is carried out according to the following steps:

[0034] a. The solar panel 1 converts solar energy into electrical energy and stores it in the battery 2 for subsequent use;

[0035] b. The electric energy stored in the battery 2 is used to power the electric flocculation component, the DC power supply 3 provides a stable voltage input for the electric flocculation reaction, and the stirrer 4 is used to maintain uniform mixing of the wastewater in the electric flocculation reactor 5 to prevent the deposition of flocculants, thereby enhancing the effect of the electric flocculation; the electric flocculation reactor 5 is equipped with an anode of waste aluminum cans 6, a cathode metal mesh 7 and high-salt oily wastewater, and the anode and the cathode are connected to the DC power supply 3 through a wire 8 to form a closed circuit; under the action of the electric field, the high-salt oily wastewater is electrolyzed in the electric flocculation reactor 5, and the aluminum of the anode dissolves and generates aluminum ions during the electrolysis process. These aluminum ions react with hydroxide in the water to generate aluminum hydroxide flocs, which can adsorb and precipitate salt and oil droplets in the wastewater to achieve solid-liquid separation;

[0036] c. After the electro-flocculation reaction is completed, the water in the electro-flocculation reactor 5 flows into the water storage tank 11 through the pipeline, and the water in the water storage tank 11 is transported to the photothermal layer 9 by capillary action. The photothermal layer 9 captures sunlight to increase the temperature at the solid-liquid interface to generate water vapor that rises to the condenser 12, condenses into droplets when it is cold, and then drips into the fresh water collector 13 under the action of gravity. This process further reduces the oil substances and salinity in the collected fresh water; the thermal insulation layer 10 above the water storage tank 11 is used to reduce heat loss to improve the energy efficiency of the system.

[0037] Conclusion: After the wastewater was treated with electroflocculation, the COD removal rate reached 90.51%, while the ion concentration in the water did not change significantly; after the electroflocculation treatment, the electroflocculation effluent was treated with solar interfacial evaporation technology, and the results showed that the COD removal rate was further reduced to 97.95%, while the ion concentration in the water (Na + Mg 2+ , K + , Ca 2+ ) has been significantly reduced and reached the World Health Organization's drinking water standards.

[0038] Example 2

[0039] The photovoltaic-assisted electro-flocculation coupled with solar interface evaporation high-salinity oily wastewater treatment system of the present invention is carried out according to Example 1, and the specific operation is carried out according to the following steps: the system is composed of a photovoltaic power generation component, an electro-flocculation component and a solar interface evaporation component; the photovoltaic power generation component is composed of a solar cell panel 1 connected to a battery 2 for converting solar energy into electrical energy and storing it; the electro-flocculation component is composed of a DC power supply 3, an agitator 4, an electro-flocculation reactor 5, waste aluminum cans 6, a metal mesh 7 and a conductor 8, and the DC power supply 3 and the stirrer 4 are connected to the battery 2 through a cable, the anode waste aluminum cans 6 and the cathode metal mesh 7 are placed inside the electric flocculation reactor 5, and the waste aluminum cans 6 and the metal mesh 7 are connected to the DC power supply 3 through a wire 8; the solar interface evaporation component is composed of a photothermal layer 9, a heat insulation layer 10, a water storage tank 11, a condenser 12 and a fresh water collector 13, the photothermal layer 9 and the heat insulation layer 10 are placed on the water storage tank 11, the condenser 12 is covered above the water storage tank 11, and a fresh water collector 13 is provided at the bottom of the water storage tank 12;

[0040] The flocculation voltage in the electro-flocculation assembly of the system is 15V, the electro-flocculation time is 20min, the distance between the cathode and the anode is 2cm, the electro-flocculation reactor 5 is made of acrylic glass, and the metal mesh 7 is made of stainless steel mesh or titanium mesh;

[0041] In the solar interface evaporation component of the system, the photothermal layer 9 is made of 0.3wt% carbon black and 0.02wt% carbon dots deposited on basalt fabric, the thermal insulation layer 10 is made of polystyrene material, the water storage tank 11 is made of acrylic glass, the condenser 12 is used to condense the water vapor generated by the photothermal layer 9 into droplets, and the fresh water collector 13 is used to collect the droplets generated by the condenser 12;

[0042] The method for treating high-salinity oily wastewater by photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation is carried out in the following steps:

[0043] a. The solar panel 1 converts solar energy into electrical energy and stores it in the battery 2 for subsequent use;

[0044] b. The electric energy stored in the battery 2 is used to power the electric flocculation component. The flocculation voltage is 15V, the electric flocculation time is 20min, the DC power supply 3 provides a stable voltage input for the electric flocculation reaction, and the stirrer 4 is used to maintain the uniform mixing of the wastewater in the electric flocculation reactor 5 to prevent the deposition of flocculants, thereby enhancing the effect of the electric flocculation; the electric flocculation reactor 5 is equipped with an anode of waste aluminum cans 6, a cathode metal mesh 7 and high-salt oily wastewater, the distance between the cathode and the anode is 2cm, and the anode and the cathode are connected to the DC power supply 3 through a wire 8 to form a closed circuit; under the action of the electric field, the high-salt oily wastewater is electrolyzed in the electric flocculation reactor 5, and the aluminum of the anode dissolves and generates aluminum ions during the electrolysis process. These aluminum ions react with hydroxide in the water to generate aluminum hydroxide flocs, which can adsorb and precipitate salt and oil droplets in the wastewater to achieve solid-liquid separation;

[0045] c. After the electro-flocculation reaction is completed, the water in the electro-flocculation reactor 5 flows into the water storage tank 11 through the pipeline, and the water in the water storage tank 11 is transported to the photothermal layer 9 by capillary action. The photothermal layer 9 captures sunlight to increase the temperature at the solid-liquid interface to generate water vapor that rises to the condenser 12, condenses into droplets when it is cold, and then drips into the fresh water collector 13 under the action of gravity. This process further reduces the oil substances and salinity in the collected fresh water; the thermal insulation layer 10 above the water storage tank 11 is used to reduce heat loss to improve the energy efficiency of the system.

[0046] Conclusion: After the wastewater was treated with electroflocculation, the COD removal rate reached 91.31%, while the ion concentration in the water did not change significantly; after the electroflocculation treatment, the electroflocculation effluent was treated with solar interfacial evaporation technology, and the results showed that the COD removal rate was further reduced to 97.98%, while the ion concentration in the water (Na + Mg 2+ , K + , Ca 2+ ) has been significantly reduced and reached the World Health Organization's drinking water standards.

[0047] Example 3

[0048] The photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation high-salinity oily wastewater treatment system of the present invention is carried out according to Example 1; the specific operation is carried out according to the following steps:

[0049] a. The solar panel 1 converts solar energy into electrical energy and stores it in the battery 2 for subsequent use;

[0050] b. The electric energy stored in the battery 2 is used to power the electric flocculation component. The flocculation voltage in the electric flocculation component is 20V, and the electric flocculation time is 10min. The DC power supply 3 provides a stable voltage input for the electric flocculation reaction. The stirrer 4 is used to maintain the uniform mixing of the wastewater in the electric flocculation reactor 5 to prevent the deposition of flocculants, thereby enhancing the effect of the electric flocculation. The electric flocculation reactor 5 is equipped with an anode of waste aluminum cans 6, a cathode metal mesh 7 and high-salt oily wastewater. The distance between the cathode and the anode is 2.5cm. The anode and the cathode are connected to the DC power supply 3 through a wire 8 to form a closed circuit. Under the action of the electric field, the high-salt oily wastewater is electrolyzed in the electric flocculation reactor 5. The aluminum of the anode dissolves and generates aluminum ions during the electrolysis process. These aluminum ions react with hydroxide in the water to generate aluminum hydroxide flocs, which can adsorb and precipitate salt and oil droplets in the wastewater to achieve solid-liquid separation.

[0051] c. After the electro-flocculation reaction is completed, the water in the electro-flocculation reactor 5 flows into the water storage tank 11 through the pipeline, and the water in the water storage tank 11 is transported to the photothermal layer 9 by capillary action. The photothermal layer 9 captures sunlight to increase the temperature at the solid-liquid interface to generate water vapor that rises to the condenser 12, condenses into droplets when it is cold, and then drips into the fresh water collector 13 under the action of gravity. This process further reduces the oil substances and salinity in the collected fresh water; the thermal insulation layer 10 above the water storage tank 11 is used to reduce heat loss to improve the energy efficiency of the system.

[0052] Conclusion: After the wastewater was treated with electroflocculation, the COD removal rate reached 92.12%, while the ion concentration in the water did not change significantly; after the electroflocculation treatment, the electroflocculation effluent was treated with solar interfacial evaporation technology, and the results showed that the COD removal rate was further reduced to 97.90%, while the ion concentration in the water (Na + Mg 2+ , K + , Ca 2+ ) has been significantly reduced and reached the World Health Organization's drinking water standards.

[0053] Example 4

[0054] The photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation high-salinity oily wastewater treatment system of the present invention is carried out according to Example 1; the specific operation is carried out according to the following steps:

[0055] a. The solar panel 1 converts solar energy into electrical energy and stores it in the battery 2 for subsequent use;

[0056] b. The electric energy stored in the battery 2 is used to power the electric flocculation component, and the DC power supply 3 provides a stable voltage input for the electric flocculation reaction. The flocculation voltage in the electric flocculation component is 12V, and the electric flocculation time is 15min. The stirrer 4 is used to maintain the uniform mixing of the wastewater in the electric flocculation reactor 5 to prevent the deposition of flocculants, thereby enhancing the effect of the electric flocculation; the electric flocculation reactor 5 is equipped with an anode waste aluminum can 6, a cathode metal mesh 7 and high-salt oily wastewater, the distance between the cathode and the anode is 1.5cm, and the anode and the cathode are connected to the DC power supply 3 through a wire 8 to form a closed circuit; under the action of the electric field, the high-salt oily wastewater is electrolyzed in the electric flocculation reactor 5, and the aluminum of the anode dissolves and generates aluminum ions during the electrolysis process. These aluminum ions react with hydroxide in the water to generate aluminum hydroxide flocs, which can adsorb and precipitate salt and oil droplets in the wastewater to achieve solid-liquid separation;

[0057] c. After the electro-flocculation reaction is completed, the water in the electro-flocculation reactor 5 flows into the water storage tank 11 through the pipeline, and the water in the water storage tank 11 is transported to the photothermal layer 9 by capillary action. The photothermal layer 9 is a basalt fabric on which 0.3wt% carbon black and 0.02wt% carbon dots are deposited. The temperature at the solid-liquid interface is increased by capturing sunlight to generate water vapor. The generated water vapor rises to the condenser 12, condenses into droplets when it is cold, and then drips into the fresh water collector 13 under the action of gravity. This process further reduces the oil substances and salinity in the collected fresh water. The thermal insulation layer 10 above the water storage tank 11 is used to reduce heat loss to improve the energy efficiency of the system.

[0058] Conclusion: After the wastewater was treated with electroflocculation, the COD removal rate reached 93.00%, while the ion concentration in the water did not change significantly; after the electroflocculation treatment, the electroflocculation effluent was treated with solar interfacial evaporation technology, and the results showed that the COD removal rate was further reduced to 97.78%, while the ion concentration in the water (Na + Mg 2+ , K + , Ca 2+ ) has been significantly reduced and reached the World Health Organization's drinking water standards.

[0059] Example 5

[0060] The photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation high-salinity oily wastewater treatment system of the present invention is carried out according to Example 1, and the specific operation is carried out according to the following steps:

[0061] a. The solar panel 1 converts solar energy into electrical energy and stores it in the battery 2 for subsequent use;

[0062] b. The electric energy stored in the battery 2 is used to power the electric flocculation component, the voltage is 1820V, the electric flocculation time is 10-30min, the DC power supply 3 provides a stable voltage input for the electric flocculation reaction, and the stirrer 4 is used to maintain the uniform mixing of the wastewater in the electric flocculation reactor 5 to prevent the deposition of flocculants, thereby enhancing the effect of the electric flocculation; the electric flocculation reactor 5 is equipped with an anode of waste aluminum cans 6, a cathode metal mesh 7 and high-salt oily wastewater, the distance between the cathode and the anode is 1-2.5cm, and the anode and the cathode are connected to the DC power supply 3 through a wire 8 to form a closed circuit; under the action of the electric field, the high-salt oily wastewater is electrolyzed in the electric flocculation reactor 5, and the aluminum of the anode dissolves and generates aluminum ions during the electrolysis process. These aluminum ions react with hydroxide in the water to generate aluminum hydroxide flocs, which can adsorb and precipitate salt and oil droplets in the wastewater to achieve solid-liquid separation;

[0063] c. After the electro-flocculation reaction is completed, the water in the electro-flocculation reactor 5 flows into the water storage tank 11 through the pipeline, and the water in the water storage tank 11 is transported to the photothermal layer 9 by capillary action. The photothermal layer 9 captures sunlight to increase the temperature at the solid-liquid interface to generate water vapor. The generated water vapor rises to the condenser 12, condenses into droplets when it is cold, and then drips into the fresh water collector 13 under the action of gravity. This process further reduces the oil substances and salinity in the collected fresh water; the thermal insulation layer 10 above the water storage tank 11 is used to reduce heat loss to improve the energy efficiency of the system.

[0064] Conclusion: After the wastewater was treated with electroflocculation, the COD removal rate reached 93.33%, while the ion concentration in the water did not change significantly; after the electroflocculation treatment, the electroflocculation effluent was treated with solar interfacial evaporation technology, and the results showed that the COD removal rate was further reduced to 97.96%, while the ion concentration in the water (Na + Mg 2+ , K + , Ca 2+ ) has been significantly reduced and reached the World Health Organization's drinking water standards.

Claims

1. A photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation system for treating high-salinity oily wastewater, characterized in that: The system is composed of a photovoltaic power generation component, an electric flocculation component and a solar interface evaporation component; the photovoltaic power generation component is composed of a solar panel (1) connected to a storage battery (2) for converting solar energy into electrical energy and storing it; the electric flocculation component is composed of a direct current power supply (3), a stirrer (4), an electric flocculation reactor (5), waste aluminum cans (6), a metal mesh (7) and a conductor (8); the direct current power supply (3) and the stirrer (4) are connected to the storage battery (2) via a cable; waste anodes are placed inside the electric flocculation reactor (5). Aluminum cans (6) and a cathode metal mesh (7), the waste aluminum cans (6) and the metal mesh (7) are connected to a direct current power source (3) via a wire (8); the solar interface evaporation component is composed of a photothermal layer (9), a heat insulation layer (10), a water storage tank (11), a condenser (12) and a fresh water collector (13), the photothermal layer (9) and the heat insulation layer (10) are placed on the water storage tank (11), the condenser (12) is covered above the water storage tank (11), and the fresh water collector (13) is provided at the bottom of the water storage tank (12).

2. A photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation high-salinity oily wastewater treatment system as claimed in claim 1, characterized in that: In the electrocoagulation component of the system, the flocculation voltage is 10-20 V, the electrocoagulation time is 10-30 min, the distance between the cathode and the anode is 1-2.5 cm, the electrocoagulation reactor (5) is made of acrylic glass, and the metal mesh (7) is made of stainless steel mesh or titanium mesh.

3. A photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation high-salinity oily wastewater treatment system as claimed in claim 1, characterized in that: In the solar interface evaporation component of the system, the photothermal layer (9) is prepared by depositing 0.3 wt% carbon black and 0.02 wt% carbon dots on basalt fabric, the thermal insulation layer (10) is made of polystyrene material, the water storage tank (11) is made of acrylic glass, the condenser (12) is used to condense the water vapor generated by the photothermal layer (9) into droplets, and the fresh water collector (13) is used to collect the droplets generated by the condenser (12).

4. A method for treating high-salinity oily wastewater by photovoltaic-assisted electro-flocculation coupled with solar interfacial evaporation as claimed in claim 1, characterized in that: Follow these steps: a. The solar panel (1) converts solar energy into electrical energy and stores it in the battery (2) for subsequent use; b. The electric energy stored in the battery (2) is used to power the electro-flocculation component, the DC power supply (3) provides a stable voltage input for the electro-flocculation reaction, and the agitator (4) is used to maintain uniform mixing of the wastewater in the electro-flocculation reactor (5). The electro-flocculation reactor (5) is equipped with an anode of waste aluminum cans (6), a cathode metal mesh (7) and high-salinity oily wastewater. The anode and the cathode are connected to the DC power supply (3) through a wire (8) to form a closed circuit. Under the action of the electric field, the high-salinity oily wastewater is electrolyzed in the electro-flocculation reactor (5). The aluminum at the anode dissolves and generates aluminum ions during the electrolysis process. The aluminum ions react with hydroxide in the water to generate aluminum hydroxide flocs, which can adsorb and precipitate salt and oil droplets in the wastewater to achieve solid-liquid separation. c. After the electrocoagulation reaction is completed, the water in the electrocoagulation reactor (5) flows into the water storage tank (11) through the pipeline, and the water in the water storage tank (11) is transported to the photothermal layer (9) by capillary action. The photothermal layer (9) captures sunlight to increase the temperature at the solid-liquid interface to generate water vapor that rises to the condenser (12), condenses into droplets when it is cold, and then drips into the fresh water collector (13) under the action of gravity.

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