Method for photoelectric integrated auxiliary biodegradation of high-salt organic wastewater and application thereof

Abstract

The application relates to a photoelectric integrated auxiliary biodegradation method for high-salt organic wastewater and application, in particular to a photoelectric integrated auxiliary biodegradation system for high-salt organic wastewater, which comprises a light enhancement system, an electrochemical system and a bioelectrochemical system, the bioelectrochemical system comprises an external resistance, 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 cavity is formed between the electrochemical anode and the electrochemical cathode, an overflow port is arranged at the top of the electrochemical cavity, the electrochemical anode and the electrochemical cathode are connected with a bioanode and the composite cathode through wires respectively, an inlet is arranged at the bottom of the electrochemical cavity, and an outlet is arranged close to the bioanode; a bioelectrochemical region is formed between the bioanode and the electrochemical cavity, and a light-enhanced bioelectrochemical region is formed between the composite cathode and the electrochemical cavity.

Description

Technical Field

[0001] This invention relates to the field of high-salt organic wastewater treatment, specifically to a photoelectric integrated assisted biodegradation system for high-salt organic wastewater. Background Technology

[0002] With the rapid development of my country's industrial and agricultural economy, freshwater resources are becoming increasingly scarce, fossil fuels are being depleted, and environmental pollution is becoming more and more prominent. Consequently, the sustainable treatment and resource utilization of wastewater have received close attention. Large quantities of high-salinity wastewater are generated in industrial processes such as marine food processing, dyeing and printing, oil and gas, and drinking water treatment. High-salinity organic wastewater has the following characteristics: complex and difficult-to-degrade organic pollutants, high chemical oxygen demand (CODcr) concentration, large fluctuations in water quality, high toxicity, high salt content, and poor biodegradability. Direct discharge or diluted discharge of untreated saline organic wastewater not only threatens the aquatic ecological environment but also wastes resources and hinders sustainable social development.

[0003] Currently, the main methods for treating high-salinity organic wastewater include coagulation sedimentation, adsorption, biological methods, and advanced oxidation processes. Coagulation sedimentation only transfers the toxic pollutants in the wastewater, without degrading them. Adsorption methods generate waste adsorbent materials that are difficult to treat, and also only transfer the pollutants without degradation. Biological methods are easily affected by the salinity and toxicity of the wastewater, resulting in low treatment efficiency. Advanced oxidation processes suffer from low TOC removal rates and the susceptibility of reactive free radicals to quenching. Therefore, developing a novel integrated technology for treating high-salinity organic wastewater that combines the advantages of various technologies while mitigating their disadvantages is of great practical significance. Summary of the Invention

[0004] This invention addresses the problems of high energy consumption, low TOC removal rate, high toxicity of recalcitrant organic pollutants, easy quenching of reactive free radicals, and easy generation of secondary halogenated toxic organic pollutants in the treatment of high-salinity wastewater. It provides a photoelectric integrated assisted biodegradation method for high-salinity organic wastewater and its application. The technical solution of this invention is as follows:

[0005] A photoelectric integrated assisted biodegradation system for high-salt organic wastewater, the system comprising a light enhancement system, an electrochemical system, and a bioelectrochemical system;

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

[0007] The light enhancement system includes a light source disposed on one side of the composite cathode;

[0008] The electrochemical system includes an electrochemical anode and an electrochemical cathode, forming an electrochemical chamber between them. An overflow port is provided at the top of the electrochemical chamber. The electrochemical anode and electrochemical cathode are connected to a bioanode and a composite cathode respectively via wires. An inlet is provided at the bottom of the electrochemical chamber, and an outlet is provided near the bioanode.

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

[0010] The bioanode consists of a carbon substrate with a biofilm and biochar attached to the biofilm. The carbon substrate can be carbon cloth or carbon felt. The biofilm is cultivated by attaching it to anaerobic sludge. After the biofilm matures, the biochar layer is attached to the surface of the biofilm to form the bioanode. The amount of biochar attached is controlled by the biochar concentration and attachment time. The biochar concentration is 0.5-1 g / L and the attachment time is 5-10 days.

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

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

[0013] The resistance is 500 to 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] In the application of the system to biodegrade high-salt organic wastewater, the high-salt organic wastewater enters the electrochemical chamber through the inlet, enters the photo-enhanced bioelectrochemical zone through the overflow outlet, and then flows horizontally to the bioelectrochemical zone. The treated effluent is discharged through the outlet.

[0016] When the optoelectronic integrated assisted biodegradation system for high-salt organic wastewater is in operation, 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 zone through the overflow port, and then flows horizontally to the bioelectrochemical zone. After being treated in the three zones, the wastewater is discharged through the outlet. The residence time of the wastewater in the system is 24 to 48 hours.

[0017] The organic pollutants involved in this invention are typical pollutants in wastewater such as pharmaceutical wastewater and high-salt wastewater from coal chemical industry; the salinity of the high-salt organic wastewater is 1%-4%, the COD is 1000-5000 mg / L, and it contains 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] This invention addresses the practical problem of effectively treating high-salinity organic wastewater. It combines the advantages of photocatalysis, bioelectrochemical technology, and electrochemical oxidation to achieve a powerful synergy, promoting the effective treatment of high-salinity organic wastewater. In this invention, the bioanode innovatively attaches biochar to the surface of the biofilm, mitigating the decrease in activity caused by direct contact between microorganisms and salt. Furthermore, the treatment via a photo-enhanced bioelectrochemical zone alleviates the low removal rate caused by chlorine quenching of free radicals, thereby improving the TOC removal rate of organic pollutants. Attached Figure Description

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

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

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

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

[0024] Figure 5 To compare the removal rates of sulfamethoxazole, phenanthrene, and COD in experiments 1-7.

[0025] Analysis of the attached chart: From Figure 4 and Figure 5As can be seen, compared with the comparative experiment, the removal rates of sulfamethoxazole, phenanthrene, and COD in the examples are relatively high. Among the four examples, the photoelectric integrated assisted biodegradation system for high-salt organic wastewater provided in Example 4 achieved the highest degradation rate, with removal rates of sulfamethoxazole, phenanthrene, and COD reaching 86.3%, 82.7%, and 94.1%, respectively. In summary, this invention organically combines photocatalysis, bioelectrochemistry, and electrochemistry to achieve efficient degradation of typical recalcitrant organic pollutants in high-salt wastewater. Detailed Implementation

[0026] Example 1

[0027] A photoelectric integrated assisted biodegradation method for high-salt organic wastewater and its application are disclosed, comprising a photo-enhancing system, an electrochemical system, and a bioelectrochemical system. The bioelectrochemical system includes a bioanode 1 and a composite cathode 2, with an external resistor 3 connected between the bioanode 1 and the composite cathode 2. The light source is located on one side of the composite cathode 2. The bioelectrochemical system also includes an electrochemical anode 6 and an electrochemical cathode 7, forming an electrochemical chamber between them. The top of the electrochemical chamber has an overflow port 5. The electrochemical anode 6 and the electrochemical cathode 7 are respectively connected to the bioanode 1 and the composite cathode 2 via wires. The bottom of the electrochemical chamber has an inlet 8, and an outlet 9 is located near the bioanode 1. A bioelectrochemical region is formed between the bioanode 1 and the electrochemical chamber, and a photo-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 photoelectric integrated assisted biodegradation system for high-salt organic wastewater are as follows:

[0029] Bioanode preparation method: Carbon cloth is used as carbon substrate, and anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm matures, a biochar layer is attached to the surface of the biofilm through acclimation to form bioanode 1. The amount of biochar attached is controlled by biochar concentration and attachment time. The biochar concentration is 0.5 g / L and the attachment time is 10 days.

[0030] The composite cathode is prepared by using carbon cloth as the carbon substrate and coating the surface of the carbon substrate with graphene catalyst.

[0031] The external resistor is 500Ω;

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

[0033] The light source in the light-enhancing region is sunlight;

[0034] In the specific embodiment, the salinity of the high-salt organic wastewater was 4%; the COD was 5000 mg / L; and the degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0035] The retention time for high-salt organic wastewater is 24 hours.

[0036] Example 2

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

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

[0039] Bioanode preparation method: Carbon cloth is used as carbon substrate, and anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm matures, a biochar layer is attached to the surface of the biofilm through acclimation to form bioanode 1. The amount of biochar attached is controlled by biochar concentration and attachment time. The biochar concentration is 0.7 g / L and the attachment time is 7 days.

[0040] The composite cathode is prepared by using a carbon brush as the carbon substrate and coating the surface of the carbon substrate with molybdenum disulfide catalyst.

[0041] The external resistor is 1000Ω;

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

[0043] The light source in the light-enhancing region 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 retention time for high-salt organic wastewater is 36 hours.

[0047] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0048] Example 3

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

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

[0051] Bioanode preparation method: Carbon cloth is used as carbon substrate, and anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm matures, a biochar layer is attached to the surface of the biofilm through acclimation to form bioanode 1. The amount of biochar attached is controlled by biochar concentration and attachment time. The biochar concentration is 1 g / L and the attachment time is 5 days.

[0052] The composite cathode is prepared by using a graphite rod as a carbon substrate and coating the surface of the carbon substrate with a catalyst, molybdenum disulfide.

[0053] The external resistor is 2000Ω;

[0054] The anode and cathode substrates in the electrochemical chamber are carbon brushes;

[0055] The light source in the light-enhanced region is artificial visible light;

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

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

[0058] The retention time for high-salt organic wastewater is 24 hours.

[0059] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0060] Example 4

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

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

[0063] Bioanode preparation method: Carbon cloth is used as carbon substrate, and anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm matures, a biochar layer is attached to the surface of the biofilm through acclimation to form bioanode 1. The amount of biochar attached is controlled by biochar concentration and attachment time. The biochar concentration is 0.8 g / L and the attachment time is 7 days.

[0064] The composite cathode is prepared by using carbon felt as the carbon substrate and coating the surface of the carbon substrate with molybdenum disulfide catalyst.

[0065] The external resistor is 1000Ω;

[0066] The anode and cathode substrates in the electrochemical chamber are graphite rods;

[0067] The light source in the light-enhancing region 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 retention time for high-salt organic wastewater is 36 hours.

[0071] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0072] Comparative Examples

[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 operating parameters of Comparative Experiments 8 to 10 are the same as those of Example 4, and the bioelectrochemical system and light enhancement system are the same as those of Example 1.

[0074] Comparative Experiment 1

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

[0076] Bioanode preparation method: Using carbon cloth as the carbon substrate, anaerobic sludge is used for acclimation and biofilm formation, and the anode biofilm is cultivated to maturity; no biochar layer is required.

[0077] The composite cathode is prepared by using carbon cloth as the carbon substrate and coating the surface of the carbon substrate with graphene catalyst.

[0078] The external resistor is 1000Ω;

[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 retention time for high-salt organic wastewater is 36 hours.

[0082] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0083] Comparative Experiment 2

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

[0085] Bioanode preparation method: Carbon cloth is used as carbon substrate, and anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm matures, a biochar layer is attached to the surface of the biofilm through acclimation to form bioanode 1. The amount of biochar attached is controlled by biochar concentration and attachment time. The biochar concentration is 0.8 g / L and the attachment time is 7 days.

[0086] The composite cathode is prepared by using carbon cloth as the carbon substrate and coating the surface of the carbon substrate with graphene catalyst.

[0087] The external resistor is 1000Ω;

[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 retention time for high-salt organic wastewater is 36 hours.

[0091] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0092] In contrast to Comparative Example 1

[0093] Comparative Experiment 3

[0094] A bioelectrochemical system was constructed using a bioanode 1, a composite cathode 2, and an external resistor 3. Light irradiation 4 was then applied to the outside of the composite cathode 2 to form a photo-enhanced bioelectrochemical system. Specific construction and operational parameters are as follows:

[0095] Bioanode preparation method: using carbon cloth as carbon substrate, anaerobic sludge is used for acclimation and biofilm formation, and the anode biofilm is cultured to maturity;

[0096] The composite cathode is prepared by using a carbon brush as the carbon substrate and coating the surface of the carbon substrate with molybdenum disulfide catalyst.

[0097] The external resistor is 1000Ω;

[0098] The light source in the light-enhancing region 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 retention time for high-salt organic wastewater is 36 hours.

[0102] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0103] Comparative Experiment 4

[0104] A bioelectrochemical system was constructed using a bioanode 1, a composite cathode 2, and an external resistor 3. Light irradiation 4 was then applied to the outside of the composite cathode 2 to form a photo-enhanced bioelectrochemical system. Specific construction and operational parameters are as follows:

[0105] Bioanode preparation method: Carbon cloth is used as carbon substrate, and anaerobic sludge is used for acclimation and biofilm formation. After the anode biofilm matures, a biochar layer is attached to the surface of the biofilm through acclimation to form bioanode 1. The amount of biochar attached is controlled by biochar concentration and attachment time. The biochar concentration is 0.8 g / L and the attachment time is 7 days.

[0106] The composite cathode is prepared by using a carbon brush as the carbon substrate and coating the surface of the carbon substrate with molybdenum disulfide catalyst.

[0107] The external resistor is 1000Ω;

[0108] The light source in the light-enhancing region 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 retention time for high-salt organic wastewater is 36 hours.

[0112] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0113] Comparative Experiment 5

[0114] A bioelectrochemical system is constructed using a bioanode 1, a composite cathode 2, and an external resistor 3. An electrochemical chamber is set within the system, with an overflow port 5 at the top. The bioelectrochemical system is connected to the electrochemical anode 6 and cathode 7 via external wires, allowing the electricity generated by the system to serve as the external electrochemical voltage. An inlet 8 is located at the bottom of the electrochemical chamber, and an outlet 9 is located near the bioanode 1. Specific construction and operating parameters are as follows:

[0115] Bioanode preparation method: using carbon cloth as carbon substrate, anaerobic sludge is used for acclimation and biofilm formation, and the anode biofilm is cultured to maturity;

[0116] The composite cathode is prepared by using a graphite rod as a carbon substrate and coating the surface of the carbon substrate with a catalyst, molybdenum disulfide.

[0117] The external resistor is 1000Ω;

[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 retention time for high-salt organic wastewater is 36 hours.

[0122] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0123] Comparative Experiment 6

[0124] A bioelectrochemical system is constructed using a bioanode 1, a composite cathode 2, and an external resistor 3. An electrochemical chamber is set within the system, with an overflow port 5 at the top. The bioelectrochemical system is connected to the electrochemical anode 6 and cathode 7 via external wires, allowing the electricity generated by the system to serve as the external electrochemical voltage. An inlet 8 is located at the bottom of the electrochemical chamber, and an outlet 9 is located near the bioanode 1. Specific construction and operating parameters are as follows:

[0125] Bioanode preparation method: Carbon cloth is used as carbon substrate, and anaerobic sludge is used for domestication and biofilm formation. After the anode biofilm is matured, a biochar layer is attached to the surface of the biofilm through domestication to form a bioanode (1). The amount of biochar attached 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] The composite cathode is prepared by using carbon felt as the carbon substrate and coating the surface of the carbon substrate with molybdenum disulfide catalyst.

[0127] The external resistor is 1000Ω;

[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 retention time for high-salt organic wastewater is 36 hours.

[0132] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0133] Comparative Experiment 7

[0134] An electrochemical chamber is constructed using an anode and cathode, with an applied voltage of 0.8V. An overflow port 5 is located at the top, an inlet 8 at the bottom, and an outlet 9 near the top. The specific parameters for construction and operation 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 retention time for high-salt organic wastewater is 36 hours.

[0139] The degradation rate of 10 mg / L antibiotic sulfamethoxazole and 0.5 mg / L polycyclic aromatic hydrocarbon phenanthrene was used as an indicator.

[0140] Comparative Experiment 8

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

[0142] Comparative Experiment 9

[0143] Compared to Example 4, the difference between Comparative Experiment 9 and Example 4 is that there is no light enhancement region, but everything else is the same.

[0144] Comparative Experiment 10

[0145] Compared to Example 4, the difference between Comparative Experiment 10 and Example 4 is the absence of the electrochemical chamber and the light-enhancing region; otherwise, they 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 skilled in the art, after learning the contents described in the present invention, several equivalent changes and substitutions can be made without departing from the principle of the present invention. These equivalent changes and substitutions should also be considered to fall within the protection scope of the present invention.

Claims

1. A photoelectric integrated 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, with a resistor connected between the bioanode and the composite cathode. The light enhancement system includes a light source disposed on one side of the composite cathode; The electrochemical system includes an electrochemical anode and an electrochemical cathode, forming an electrochemical chamber between them. An overflow port is provided at the top of the electrochemical chamber. The electrochemical anode and electrochemical cathode are connected to a bioanode and a composite cathode respectively via wires. An inlet is provided at the bottom of the electrochemical chamber, and an outlet is provided near the bioanode. A bioelectrochemical region is formed between the bioanode and the electrochemical chamber, and a photo-enhanced bioelectrochemical region is formed between the composite cathode and the electrochemical chamber.

2. The system as described in claim 1, characterized in that, The bioanode is a carbon substrate with a biofilm on it, and biochar is attached to the biofilm.

3. The system as described in claim 2, characterized in that, The preparation method of the bioanode is as follows: the carbon substrate is selected as carbon cloth or carbon felt, the biofilm is cultured by anaerobic sludge film attachment, and after the biofilm matures, the biochar layer is attached to the surface of the biofilm to form a bioanode; the amount of biochar attached is controlled by the biochar concentration and attachment time, the biochar concentration is 0.5-1 g / L, and the attachment time is 5-10 days.

4. The system as described in claim 1, characterized in that, The composite cathode is prepared by selecting one of carbon cloth, carbon brush, carbon felt, or graphite rod as the carbon substrate and bonding graphene or molybdenum disulfide catalyst to the surface of the carbon substrate.

5. The system as described in claim 1, characterized in that, The electrode substrates for the electrochemical anode and electrochemical cathode are one of graphite rods, carbon felt, or carbon brushes.

6. The system as described in claim 1, characterized in that, The resistance is 500 to 2000 Ω.

7. The system as described in 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 as described in claim 1, characterized in that, When the system is in operation, the wastewater to be treated enters the electrochemical chamber through the inlet, enters the photo-enhanced bioelectrochemical zone through the overflow outlet, and then flows horizontally to the bioelectrochemical zone. After being treated in the three zones, it is discharged through the outlet. The residence time of the wastewater in the system is 24 to 48 hours.

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

10. The application as described in claim 9, characterized in that, The high-salt organic wastewater has a salinity of 1%-4% and a COD of 1000-5000 mg / L, and contains toxic pollutants such as sulfamethoxazole and / or polycyclic aromatic hydrocarbons (PAHs).

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