Photoelectric integration assisted biodegradation method for high-salt organic wastewater and application of photoelectric integration assisted biodegradation method

Abstract

The invention relates to a photoelectric integration assisted biodegradation method for high-salinity organic wastewater and application, in particular to a photoelectric integration assisted biodegradation system for high-salinity organic wastewater, the system comprises a light enhancement system, an electrochemical system and a bioelectrochemical system, the bioelectrochemical system comprises an external resistor, and a light source is arranged on one side of a composite cathode; an electrochemical anode and an electrochemical cathode are arranged in the bioelectrochemical system, an electrochemical chamber is formed between the electrochemical anode and the electrochemical cathode, an overflow port is formed in the top of the electrochemical chamber, and the electrochemical anode and the electrochemical cathode are connected with a biological anode and a composite cathode through wires respectively; an inlet is formed in the bottom of the electrochemical chamber, and an outlet is formed close to the biological anode; a bioelectrochemical region is formed between the biological anode and the electrochemical chamber, and a light-enhanced bioelectrochemical region is formed between the composite cathode and the electrochemical chamber.

Description

Technical Field

[0001] The present invention relates to the field of high-salt organic wastewater treatment, and particularly to an optoelectronic integrated assisted biodegradation system for high-salt organic wastewater. Background Art

[0002] With the rapid development of China's industrial and agricultural economy, the problems of freshwater shortage, fossil fuel depletion, and environmental pollution have become increasingly prominent. As a result, the sustainable treatment and resource utilization of wastewater have received close attention. In industrial treatment processes such as the marine food products industry, the printing and dyeing industry, the oil and gas industry, and drinking water treatment, a large amount of high-salinity wastewater is generated. High-salt organic wastewater has the following characteristics: complex and difficult-to-degrade organic pollutants, high chemical oxygen demand (CODcr) concentration, large water quality variations, high toxicity, high salt content, and poor biodegradability. Discharging untreated saline organic wastewater directly or after dilution not only poses a threat to the water ecological environment but also causes waste of resources and is not conducive to the sustainable development of society.

[0003] Currently, the methods for treating high-salt organic wastewater mainly include: coagulation sedimentation method, adsorption method, biological method, and advanced oxidation method, etc. The coagulation sedimentation method only transfers the toxic pollutants in the high-salt organic wastewater to another phase and does not degrade them; the waste adsorption materials generated by the adsorption method are difficult to treat, and the adsorption method also only transfers the pollutants to another phase without degradation. The biological method is easily affected by the salinity and toxic pollutants in high-salt organic wastewater, resulting in low treatment efficiency, while the advanced oxidation method has problems such as low TOC removal rate and easy quenching of active free radicals. Therefore, how to integrate the advantages of various technologies and avoid their disadvantages to develop a new type of high-salt organic wastewater treatment technology has strong application significance. Summary of the Invention

[0004] In view of the problems such as high energy consumption, low TOC removal rate, high toxicity of difficult-to-degrade organic pollutants, easy quenching of active free radicals, and easy generation of secondary halogenated toxic organic pollutants during the treatment of high-salt wastewater, the present invention provides an optoelectronic integrated assisted biodegradation method for high-salt organic wastewater and its application. The technical solution of the present invention is as follows:

[0005] An optoelectronic integrated assisted biodegradation system for high-salt organic wastewater, the system includes a light enhancement system, an electrochemical system, and a bioelectrochemical system;

[0006] The bioelectrochemical system includes a bioanode and a composite cathode, and a resistor is connected between the bioanode and the composite cathode;

[0007] The light enhancement system includes a light source, which is arranged on one side of the composite cathode;

[0008] The electrochemical system is provided with an electrochemical anode and an electrochemical cathode. An electrochemical chamber is formed between the electrochemical anode and the electrochemical cathode. An overflow port is provided at the top of the electrochemical chamber. The electrochemical anode and the electrochemical cathode are respectively connected to a biological anode and a composite cathode through wires. An inlet is provided at the bottom of the electrochemical chamber, and an outlet is provided near the biological anode.

[0009] A bioelectrochemical region is formed between the biological anode and the electrochemical chamber, and a photo-enhanced bioelectrochemical region is formed between the composite cathode and the electrochemical chamber.

[0010] The biological anode is a carbon substrate with a biofilm, and biochar is attached to the biofilm. The carbon substrate is selected from carbon cloth or carbon felt. The biofilm is cultured by attaching anaerobic sludge. After the biofilm is cultured maturely, a biochar layer is attached to the surface of the biofilm to form a biological anode. The attachment amount of biochar is controlled by the biochar concentration and the attachment time. The biochar concentration is 0.5 - 1 g / L, and the attachment time is 5 - 10 d.

[0011] The composite cathode selects one of carbon cloth, carbon brush, carbon felt, and graphite rod as the carbon substrate, and is prepared by combining (coating method) graphene or molybdenum disulfide catalyst on the surface of the carbon substrate.

[0012] The electrode substrates of the electrochemical anode and the electrochemical cathode are carbon materials, and the carbon materials are graphite rods, carbon felt, or carbon brushes.

[0013] The resistance is 500 - 2000 Ω.

[0014] The light source is sunlight, a 150W - 300W xenon lamp as artificial visible light, or an 18W - 36W ultraviolet light source.

[0015] The application of the system in biodegradation of high-salt organic wastewater. The high-salt organic wastewater enters the electrochemical chamber through the inlet, enters the photo-enhanced bioelectrochemical region through the overflow port, and then flows horizontally to the bioelectrochemical region. The treated effluent is discharged through the outlet.

[0016] When the optoelectronic integration-assisted biological degradation high-salt organic wastewater system is in the working state, the wastewater to be treated enters the electrochemical chamber through the inlet at the bottom of the electrochemical chamber, then enters the photo-enhanced bioelectrochemical region through the overflow port, and then flows horizontally to the bioelectrochemical region. After being treated in the three regions, it is discharged through the outlet. The residence time of the wastewater to be treated in the system is 24 - 48 h.

[0017] The organic pollutants involved in the present invention are typical pollutants in wastewater such as pharmaceutical wastewater and high-salt coal chemical wastewater; the salinity of the high-salt organic wastewater is 1%-4%, the COD is 1000-5000 mg / L, and the toxic pollutants contained are at least one of antibiotics or polycyclic aromatic hydrocarbons; specifically, the toxic pollutants involved in the examples are sulfamethoxazole and / or polycyclic aromatic hydrocarbon phenanthrene.

[0018] Beneficial effects

[0019] Based on the practical problem of effective treatment of high-salt organic wastewater, the present invention combines the advantages of photocatalysis technology, bioelectrochemical technology and electrochemical oxidation technology to achieve the combination of multiple technologies and promote the effective treatment of high-salt organic wastewater. In the present invention, the biological anode innovatively attaches biochar to the surface of the biofilm, alleviating the phenomenon of decreased activity caused by direct contact between microorganisms and salt. Through the treatment of the photo-enhanced bioelectrochemical region in the present invention, the disadvantage of low removal rate caused by the quenching of free radicals by chlorine is alleviated, and the TOC removal rate of organic pollutants is improved. Description of the drawings

[0020] Figure 1 It is a schematic structural diagram of a system for photoelectric integrated assisted biodegradation of high-salt organic wastewater of the present invention. In the figure: 1. Biological anode; 2. Composite cathode; 3. Resistor; 4. Light source; 5. Overflow port; 6. Electrochemical anode; 7. Electrochemical cathode; 8. Inlet; 9. Outlet.

[0021] Figure 2 It is a schematic structural diagram of the biological anode in the system for photoelectric integrated assisted biodegradation of high-salt organic wastewater of the present invention.

[0022] Figure 3 It is a schematic structural diagram of the composite cathode in the system for photoelectric integrated assisted biodegradation of high-salt organic wastewater of the present invention.

[0023] Figure 4 It is the removal rates of sulfamethoxazole, phenanthrene and COD in Examples 1-4.

[0024] Figure 5 It is the removal rates of sulfamethoxazole, phenanthrene and COD in Comparative Experiments 1-7.

[0025] Analysis of the drawings: From Figure 4 and Figure 5It can be seen that, compared with the comparative experiment, the removal rates of sulfamethoxazole, phenanthrene and COD in the examples are relatively high. Among them, in the 4 groups of examples, the photo-electro-integrated assisted biodegradation system for high-salt organic wastewater provided in Example 4 achieved the highest material degradation, and the removal rates of sulfamethoxazole, phenanthrene and COD reached 86.3%, 82.7% and 94.1% respectively. Generally speaking, the present invention combines photocatalysis, bioelectrochemistry and electrochemistry organically to achieve the efficient degradation of typical refractory organic pollutants in high-salt wastewater. Detailed implementation mode

[0026] Example 1

[0027] A method for photo-electro-integrated assisted biodegradation of high-salt organic wastewater and its application, including a light enhancement system, an electrochemical system and a bioelectrochemical system. The bioelectrochemical system includes a biological anode 1 and a composite cathode 2. An external resistor 3 is connected between the biological anode 1 and the composite cathode 2. The light source is arranged on one side of the composite cathode 2. An electrochemical anode 6 and an electrochemical cathode 7 are arranged in the bioelectrochemical system. An electrochemical chamber is formed between the electrochemical anode 6 and the electrochemical cathode 7. An overflow port 5 is arranged at the top of the electrochemical chamber. The electrochemical anode 6 and the electrochemical cathode 7 are respectively connected to the biological anode 1 and the composite cathode 2 through wires. An inlet 8 is arranged at the bottom of the electrochemical chamber, and an outlet 9 is arranged near the biological anode 1. A bioelectrochemical region is formed between the biological anode 1 and the electrochemical chamber, and a light-enhanced bioelectrochemical region is formed between the composite cathode 2 and the electrochemical chamber.

[0028] The specific parameters for the construction and operation of a photo-electro-integrated assisted biodegradation system for high-salt organic wastewater are as follows:

[0029] Preparation method of biological anode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and film formation. After the anode biofilm is cultured and matured, a biochar layer is attached to the surface of the biofilm through acclimation to form the biological anode 1. The biochar attachment amount is controlled by the biochar concentration and the attachment time. The biochar concentration is 0.5 g / L, and the attachment time is 10 d.

[0030] Preparation method of composite cathode: Using carbon cloth as the carbon substrate, the catalyst graphene is coated on the surface of the carbon substrate.

[0031] The external resistor is 500 Ω.

[0032] The anode and cathode substrates in the electrochemical chamber are graphite rods.

[0033] The light source in the light-enhanced region is sunlight.

[0034] In the specific embodiment, the salinity of the high-salt organic wastewater is 4%; the COD is 5000 mg / L; the degradation rates of 10 mg / L of the antibiotic sulfamethoxazole and 0.5 mg / L of the polycyclic aromatic hydrocarbon phenanthrene are used as indicators

[0035] The residence time of the high-salt organic wastewater is 24 h.

[0036] Example 2

[0037] The method for photoelectric integrated assisted biodegradation of high-salt organic wastewater and its application structure are the same as those in Example 1.

[0038] The construction and operation specific parameters of a system for photoelectric integrated assisted biodegradation of high-salt organic wastewater are as follows:

[0039] Preparation method of the biocathode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm is cultivated and matured, a biochar layer is attached to the surface of the biofilm by acclimation to form the biocathode 1. The biochar attachment amount is controlled by the biochar concentration and the attachment time. The biochar concentration is 0.7 g / L and the attachment time is 7 d;

[0040] Preparation method of the composite cathode: Using a carbon brush as the carbon substrate, the catalyst molybdenum disulfide is coated on the surface of the carbon substrate;

[0041] The external resistance is 1000 Ω;

[0042] The anode and cathode substrates in the electrochemical chamber are carbon felt;

[0043] The light source in the light enhancement area is ultraviolet light;

[0044] The salinity of the high-salt organic wastewater is 3%;

[0045] The COD of the high-salt organic wastewater is 3000 mg / L;

[0046] The residence time of the high-salt organic wastewater is 36 h;

[0047] The degradation rates of 10 mg / L of the antibiotic sulfamethoxazole and 0.5 mg / L of the polycyclic aromatic hydrocarbon phenanthrene are used as indicators.

[0048] Example 3

[0049] The method for photoelectric integrated assisted biodegradation of high-salt organic wastewater and its application structure are the same as those in Example 1.

[0050] The construction and operation specific parameters of a system for photoelectric integrated assisted biodegradation of high-salt organic wastewater are as follows:

[0051] Preparation method of biological anode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and film formation. After the anode biofilm is cultured and matured, a biochar layer is attached to the surface of the biofilm through acclimation to form biological anode 1. The biochar attachment amount is controlled by the biochar concentration and attachment time. The biochar concentration is 1 g / L and the attachment time is 5 d;

[0052] Preparation method of composite cathode: Using a graphite rod as the carbon substrate, the catalyst molybdenum disulfide is coated on the surface of the carbon substrate;

[0053] The external resistance is 2000 Ω;

[0054] In the electrochemical chamber, the anode and cathode substrates are carbon brushes;

[0055] In the light enhancement area, the light source is artificial visible light;

[0056] The salinity of the high-salt organic wastewater is 1%;

[0057] The COD of the high-salt organic wastewater is 1000 mg / L;

[0058] The residence time of the high-salt organic wastewater is 24 h;

[0059] Using the degradation rates of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0060] Example 4

[0061] The method for photoelectric integrated assisted biodegradation of high-salt organic wastewater and its application structure are the same as those in Example 1.

[0062] The construction and operation specific parameters of a photoelectric integrated assisted biodegradation high-salt organic wastewater system are as follows:

[0063] Preparation method of biological anode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and film formation. After the anode biofilm is cultured and matured, a biochar layer is attached to the surface of the biofilm through acclimation to form biological anode 1. The biochar attachment amount is controlled by the biochar concentration and attachment time. The biochar concentration is 0.8 g / L and the attachment time is 7 d;

[0064] Preparation method of composite cathode: Using carbon felt as the carbon substrate, the catalyst molybdenum disulfide is coated on the surface of the carbon substrate;

[0065] The external resistance is 1000 Ω;

[0066] In the electrochemical chamber, the anode and cathode substrates are graphite rods;

[0067] In the light enhancement area, the light source is ultraviolet light;

[0068] The salinity of the high-salt organic wastewater is 2%;

[0069] The COD of the high-salt organic wastewater is 2000 mg / L;

[0070] The residence time of the high-salt organic wastewater is 36 h;

[0071] Taking the degradation rates of 10 mg / L of the antibiotic sulfamethoxazole and 0.5 mg / L of the polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0072] Comparative example

[0073] Unless otherwise stated, the system structures of Comparative Experiments 1 to 7 are the same as those of Example 1, including a light enhancement system, an electrochemical system, and a bioelectrochemical system; the preparation methods of the bioanode and composite cathode and the system operation parameters of Comparative Experiments 8 to 10 are the same as those of Example 4, and the bioelectrochemical system and the light enhancement system are the same as those of Example 1.

[0074] Comparative Experiment 1

[0075] A bioelectrochemical system is constructed by a bioanode 1, a composite cathode 2, and an external resistor 3. The specific construction and operation parameters are as follows:

[0076] Preparation method of the bioanode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and biofilm formation, and the anode biofilm is cultured to maturity; there is no biochar layer

[0077] The preparation method of the composite cathode is: Using carbon cloth as the carbon substrate, the catalyst graphene is coated on the surface of the carbon substrate;

[0078] The external resistor is 1000 Ω;

[0079] The salinity of the high-salt organic wastewater is 2%;

[0080] The COD of the high-salt organic wastewater is 2000 mg / L;

[0081] The residence time of the high-salt organic wastewater is 36 h;

[0082] Taking the degradation rates of 10 mg / L of the antibiotic sulfamethoxazole and 0.5 mg / L of the polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0083] Comparative Experiment 2

[0084] A bioelectrochemical system is constructed by a bioanode 1, a composite cathode 2, and an external resistor 3. The specific construction and operation parameters are as follows:

[0085] Preparation method of the bioanode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm is cultured to maturity, the biofilm surface is attached with a biochar layer by acclimation to form the bioanode 1. The biochar attachment amount is controlled by the biochar concentration and the attachment time. The biochar concentration is 0.8 g / L, and the attachment time is 7 d;

[0086] The preparation method of the composite cathode is as follows: using carbon cloth as the carbon substrate, and coating the catalyst graphene on the surface of the carbon substrate;

[0087] The external resistance is 1000 Ω;

[0088] The salinity of the high-salt organic wastewater is 2%;

[0089] The COD of the high-salt organic wastewater is 2000 mg / L;

[0090] The residence time of the high-salt organic wastewater is 36 h;

[0091] Taking the degradation rates of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0092] Form a comparison with Comparative Example 1

[0093] Comparative Experiment 3

[0094] Construct a bioelectrochemical system through the bioanode 1, the composite cathode 2 and the external resistance 3, and perform light irradiation 4 outside the composite cathode 2 to form a photo-enhanced bioelectrochemical system. The specific parameters for construction and operation are as follows:

[0095] The preparation method of the bioanode: using carbon cloth as the carbon substrate, domesticating and hanging the film with anaerobic sludge, and culturing the anode biofilm to maturity;

[0096] The preparation method of the composite cathode is as follows: using a carbon brush as the carbon substrate, and coating the catalyst molybdenum disulfide on the surface of the carbon substrate;

[0097] The external resistance is 1000 Ω;

[0098] The light source in the photo-enhanced area is ultraviolet light;

[0099] The salinity of the high-salt organic wastewater is 2%;

[0100] The COD of the high-salt organic wastewater is 2000 mg / L;

[0101] The residence time of the high-salt organic wastewater is 36 h;

[0102] Taking the degradation rates of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0103] Comparative Experiment 4

[0104] Construct a bioelectrochemical system through the bioanode 1, the composite cathode 2 and the external resistance 3, and perform light irradiation 4 outside the composite cathode 2 to form a photo-enhanced bioelectrochemical system. The specific parameters for construction and operation are as follows:

[0105] Method for preparing biological anode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm is cultured to maturity, a biochar layer is attached to the surface of the biofilm through acclimation to form biological anode 1. The biochar attachment amount is controlled by the biochar concentration and the attachment time. The biochar concentration is 0.8 g / L and the attachment time is 7 days;

[0106] Method for preparing composite cathode: Using carbon brush as the carbon substrate, the catalyst molybdenum disulfide is coated on the surface of the carbon substrate;

[0107] The external resistance is 1000 Ω;

[0108] The light source in the light enhancement area is ultraviolet light;

[0109] The salinity of the high-salt organic wastewater is 2%;

[0110] The COD of the high-salt organic wastewater is 2000 mg / L;

[0111] The residence time of the high-salt organic wastewater is 36 h;

[0112] Using the degradation rates of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0113] Comparative experiment 5

[0114] Construct a bioelectrochemical system through biological anode 1, composite cathode 2 and external resistance 3; Set up an electrochemical chamber in the bioelectrochemical system, set an overflow port 5 at the top, connect the bioelectrochemical system with the electrochemical anode 6 and cathode 7 through external wires to realize the power generation of the bioelectrochemical system as the electrochemical applied voltage. Set an inlet 8 at the bottom of the electrochemical chamber and an outlet 9 near biological anode 1. The specific parameters for construction and operation are:

[0115] Method for preparing biological anode: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and biofilm formation, and the anode biofilm is cultured to maturity;

[0116] Method for preparing composite cathode: Using graphite rod as the carbon substrate, the catalyst molybdenum disulfide is coated on the surface of the carbon substrate;

[0117] The external resistance is 1000 Ω;

[0118] The anode and cathode substrates in the electrochemical chamber are graphite rods;

[0119] The salinity of the high-salt organic wastewater is 2%;

[0120] The COD of the high-salt organic wastewater is 2000 mg / L;

[0121] The residence time of the high-salt organic wastewater is 36 h;

[0122] Using the degradation rates of 10 mg / L of the antibiotic sulfamethoxazole and 0.5 mg / L of the polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0123] Comparative experiment 6

[0124] Construct a bioelectrochemical system through bioanode 1, composite cathode 2 and external resistor 3; set up an electrochemical chamber in the bioelectrochemical system, set an overflow port 5 at the top, connect the bioelectrochemical system with electrochemical anode 6 and cathode 7 through external wires to realize the electricity generation of the bioelectrochemical system as the electrochemical applied voltage. Set an inlet 8 at the bottom of the electrochemical chamber and an outlet 9 near the bioanode 1. The specific construction and operation parameters are as follows:

[0125] Preparation method of bioanode: Using carbon cloth as the carbon substrate, domesticating and forming a biofilm with anaerobic sludge. After the anode biofilm is cultured and matured, a biochar layer is attached to the surface of the biofilm through domestication to form a bioanode (1). The biochar attachment amount is controlled by the biochar concentration and attachment time. The biochar concentration is 0.8 g / L and the attachment time is 7 days;

[0126] Preparation method of the composite cathode: Using carbon felt as the carbon substrate, coating the surface of the carbon substrate with the catalyst molybdenum disulfide;

[0127] The external resistor is 1000 Ω;

[0128] The anode and cathode substrates in the electrochemical chamber are graphite rods;

[0129] The salinity of the high-salt organic wastewater is 2%;

[0130] The COD of the high-salt organic wastewater is 2000 mg / L;

[0131] The residence time of the high-salt organic wastewater is 36 h;

[0132] Using the degradation rates of 10 mg / L of the antibiotic sulfamethoxazole and 0.5 mg / L of the polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0133] Comparative experiment 7

[0134] Set up an electrochemical chamber through the anode and cathode, with an applied voltage of 0.8 V, set an overflow port 5 at the top, set an inlet 8 at the bottom of the electrochemical chamber, and set an outlet 9 near the top. The specific construction and operation parameters are as follows:

[0135] The anode and cathode substrates in the electrochemical chamber are graphite rods;

[0136] The salinity of the high-salt organic wastewater is 2%;

[0137] The COD of the high-salt organic wastewater is 2000 mg / L;

[0138] The residence time of the high-salt organic wastewater is 36 h;

[0139] Taking the degradation rates of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene as indicators.

[0140] Comparative Experiment 8

[0141] Compared with Example 4, the difference between Comparative Experiment 8 and Example 4 is that there is no electrochemical chamber, and the others are the same.

[0142] Comparative Experiment 9

[0143] Compared with Example 4, the difference between Comparative Experiment 9 and Example 4 is that there is no light enhancement area, and the others are the same.

[0144] Comparative Experiment 10

[0145] Compared with Example 4, the difference between Comparative Experiment 10 and Example 4 is that there is no electrochemical chamber and no light enhancement area, and the others are the same.

[0146] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. For those of ordinary skill in the art in this technical field, after learning the content recorded in the present invention, without departing from the principle of the present invention, several equivalent transformations and substitutions can still be made, and these equivalent transformations and substitutions should also be regarded as belonging to the protection scope of the present invention.

Claims

1. An optoelectronic integration-assisted biodegradation system for high-salt organic wastewater, characterized in that, The system includes a light enhancement system, an electrochemical system and a bioelectrochemical system; The bioelectrochemical system includes a bioanode and a composite cathode, and a resistor is connected between the bioanode and the composite cathode; The light enhancement system includes a light source, which is arranged on one side of the composite cathode; In the electrochemical system, there are an electrochemical anode and an electrochemical cathode. An electrochemical chamber is formed between the electrochemical anode and the electrochemical cathode. An overflow port is arranged at the top of the electrochemical chamber. The electrochemical anode and the electrochemical cathode are respectively connected to the bioanode and the composite cathode through wires. An inlet is arranged at the bottom of the electrochemical chamber, and an outlet is arranged near the bioanode; A bioelectrochemical region is formed between the bioanode and the electrochemical chamber, and a light-enhanced bioelectrochemical region is formed between the composite cathode and the electrochemical chamber.

2. The system according to claim 1, wherein The bioanode is a carbon substrate with a biofilm, and biochar is attached to the biofilm.

3. The system according to claim 2, wherein The preparation method of the bioanode is as follows: the carbon substrate is selected from carbon cloth or carbon felt. The biofilm is cultivated by anaerobic sludge hanging film. After the biofilm is cultivated maturely, a biochar layer is attached to the surface of the biofilm to form a bioanode. The attachment amount of biochar is controlled by the biochar concentration and the attachment time. The biochar concentration is 0.5-1 g / L, and the attachment time is 5-10 d.

4. The system according to claim 1, wherein The composite cathode selects one of carbon cloth, carbon brush, carbon felt, and graphite rod as the carbon substrate, and is prepared by combining graphene or molybdenum disulfide catalyst on the surface of the carbon substrate.

5. The system according to claim 1, wherein The electrode substrates of the electrochemical anode and the electrochemical cathode are one of graphite rods, carbon felt or carbon brushes.

6. The system according to claim 1, wherein The resistor is 500-2000 Ω.

7. The system according to claim 1, characterized in that, The light source is sunlight, a 150W-300W xenon lamp as artificial visible light or an 18W-36W ultraviolet light source.

8. The system according to claim 1, characterized in that, When the system is in a working state, the wastewater to be treated enters the electrochemical chamber through the inlet, enters the light-enhanced bioelectrochemical region through the overflow port, then flows horizontally to the bioelectrochemical region, and is discharged through the outlet after being treated in the three regions. The residence time of the wastewater to be treated in the system is 24-48 h.

9. An application of the system according to claim 1, characterized in that, This system is applied to treat the high-salt organic wastewater generated in chemical production.

10. The application according to claim 9, wherein The salinity of the high-salt organic wastewater is 1%-4%, the COD is 1000-5000 mg / L, and the toxic pollutants contained are sulfamethoxazole and / or polycyclic aromatic hydrocarbon phenanthrene.

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