Method and system for improving the biodegradability of sewage

Abstract

The application discloses a method for improving the biodegradability of sewage, which comprises the following steps: (1) pretreatment: double-alkali hardness removal and physicochemical coagulation treatment are performed on the sewage; (2) chemical oxidation treatment: the pretreated sewage is subjected to chemical oxidation through an oxidizing agent; (3) electrochemical oxidation treatment: the chemically oxidized sewage is subjected to electrochemical oxidation treatment; (4) internal circulation mixing treatment: the effluent of step (3) and the effluent of step (2) are subjected to internal circulation mixing treatment at a certain ratio; and (5) real-time regulation: a wisdom judgment system is set, and the chlorine dioxide concentration, the effective chlorine concentration and the SCOD concentration in the effluent of step (4) before entering a biochemical system are regulated in real time according to the wisdom judgment system. The application further provides a system for improving the biodegradability of sewage. The method and the system of the application are widely applicable, the side effects of electrochemical reaction peroxidation can be eliminated through internal circulation mixing in the system, the biodegradability of the sewage is significantly improved, the energy utilization rate and the sewage treatment capacity are greatly improved, and therefore the operation cost of the whole system is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of sewage treatment, and particularly relates to a method and system for improving the biodegradability of sewage. BACKGROUND

[0002] High-salt chemical wastewater, petrochemical wastewater, landfill leachate, pharmaceutical wastewater and other high-salt and high-concentration wastewater generally have the characteristics of high salt content, high pollutant concentration and strong biological toxicity, and have very poor biodegradability, which has a strong inhibitory effect on the biochemical system of sewage treatment. Electrochemical technology can achieve ring-opening and chain-breaking of part of organic matter, and decompose macromolecular organic matter into small molecular organic matter for microbial absorption and utilization. When the chlorine ion content in the sewage is relatively high, reaching 5000 mg / L or more, the chlorine ion will be converted into Cl2, ClO2, ClO2 - , ClO - , ClO3 - , etc. When the sulfate content is relatively high, reaching 5000 mg / L or more, O3, ·S2O8 2- , etc. will also be generated. These components have a long residence time and strong oxidizing properties, which can damage the cell membrane of microorganisms, and at the same time react with the intracellular substances to produce qualitative changes, thereby producing a certain toxic effect on microorganisms, thereby reducing the degradation ability of the biochemical system to pollutants.

[0003] A Chinese patent document (publication number: CN107746164B) discloses an electrochemical-AAO device for reducing the amount of sludge in sewage treatment and a treatment method thereof. The sludge is subjected to electrokinetics by an electrochemical treatment method to form a sludge electrochemical cracking reduction unit, and the sludge cracking reduction is achieved by the electric effect between the two poles. The sewage in the aerobic tank after electrochemical pretreatment is introduced into the sludge sedimentation tank through a pipeline for sludge sedimentation. The sludge in the sedimentation tank is backflowed to the anaerobic tank by a sludge backflow pump, and the backflow sludge after electrochemical treatment has improved biodegradability. The patent mainly solves the problem of sludge aging by electrochemistry, converts the sludge into a carbon source, and thereby improves the biodegradability of the sewage, but does not solve the problem of low biodegradability of the pollutants in the sewage itself.

[0004] The Chinese patent document (publication number: CN213446721U) discloses a sewage treatment device based on electrochemistry and biological filtration, which comprises a water tank, an electrochemical oxidation device and a biological filter tank. The electrochemical oxidation device comprises a first reaction tank and a second reaction tank. The first reaction tank has a plurality of sieve holes in the bottom plate, and the top of the side wall of the first reaction tank is connected to the bottom of the second reaction tank through an overflow pipe. The top of the side wall of the second reaction tank, away from the overflow pipe, is connected to the biological filter tank through a drain pipe. A plurality of electrode plates are arranged in the first reaction tank and the second reaction tank at intervals, and adjacent electrode plates are electrically connected to opposite electrodes. In the utility model, the biochemical tail water undergoes electrolytic reaction under the action of the electrode plates when flowing through the first reaction tank and the second reaction tank, and the pollutants in the wastewater are oxidized and decomposed. Long-chain macromolecular organic matter is decomposed into small-molecule organic matter, effectively improving the biodegradability of the biochemical tail water, and the oxidation effect is excellent. However, the patent does not solve the problem of the toxicity of O3, O - 、·S2O8 2- 、Cl2, ClO2, ClO2 - 、ClO - and other oxidizing substances to the microorganisms in the biochemical system.

[0005] The Chinese patent document (publication number: CN214990455U) discloses an external electrochemical treatment device for urban sewage pretreatment, which comprises a box body, a perforated aeration pipe fixed on the two walls of the box body, and a fan connected to one end of the perforated aeration pipe. The box body is provided with an electrochemical device for treating sewage. The box body is provided with a sludge collection device for concentrating sludge. The box body is provided with a sludge pumping device for pumping excess sludge in the box body. The utility model increases the alkalinity of the sewage through electrochemical reaction, which is helpful for subsequent biological treatment. It can reduce the risk of system being impacted by toxic and harmful substances, and is helpful for stable operation of the subsequent biochemical system. It improves the biodegradability of the sewage and lays a foundation for subsequent biochemical treatment. The electrochemical device can remove part of the total phosphorus in the sewage during operation. The external electrochemical device has a sedimentation function. However, the patent does not solve the problem of the toxicity of O3, O - 、·S2O8 2- 、Cl2, ClO2, ClO2 - 、ClO - and other oxidizing substances to the microorganisms in the biochemical system. SUMMARY

[0006] In view of the defects of strong oxidation of the effluent of the traditional electrochemical process and limitation of the function of the biochemical system, the technical problem to be solved by the present application is to provide a method and system for improving the biodegradability of sewage without adding external agents, effectively solving the toxicity of oxidizing substances to the microorganisms in the subsequent biochemical system, and improving the overall sewage pretreatment capacity at low cost.

[0007] In order to achieve the above-mentioned purpose, the present application adopts the following technical effects:

[0008] According to one aspect of the present application, a method for improving the biodegradability of sewage is provided, comprising the following steps:

[0009] (1) Pretreatment: double-alkali hardness removal and physicochemical coagulation treatment of the sewage;

[0010] (2) Chemical oxidation treatment: chemical oxidation of the pretreated sewage by an oxidizing agent;

[0011] (3) Electrochemical oxidation treatment: electrochemical oxidation treatment of the chemically oxidized sewage;

[0012] (4) Internal circulation mixing treatment: internal circulation mixing treatment of the effluent of step (3) with the effluent of step (2) in a certain proportion;

[0013] (5) Real-time regulation: setting up an intelligent judgment system to real-time regulate the chlorine dioxide concentration, effective chlorine concentration and SCOD concentration in the effluent of step (4) before entering the biochemical system.

[0014] Preferably, in step (1), the double-alkali hardness removal treatment specifically adjusts the pH of the sewage to 8-12, adds a certain amount of sodium carbonate according to the hardness of the sewage, and then adds polyiron and / or polyaluminum and polyacrylamide to precipitate calcium, magnesium and silicates in the sewage, thereby reducing the hardness of the sewage.

[0015] Preferably, in step (1), the physicochemical coagulation treatment specifically uses a coagulant to treat the sewage, wherein the coagulant is one or more of iron salts, aluminum salts and titanium salts. The iron salts include but are not limited to polyaluminum chloride, polyferric sulfate, ferric chloride and ferric sulfate; the aluminum salts include but are not limited to polyaluminum chloride, polyaluminum sulfate, aluminum sulfate and alum; and the titanium salts include but are not limited to polyaluminum titanium sulfate.

[0016] The present application removes most of the calcium, magnesium, suspended solids and part of the macromolecular organic matter by double-alkali hardness removal and physicochemical coagulation of the sewage, thereby removing them by deposition, net capture, adsorption bridging, and electric neutralization.

[0017] Preferably, in step (2), the oxidizing agent is one or more of sodium hypochlorite, sodium chlorite, chlorine dioxide, sodium peroxide, ozone and hydrogen peroxide. By chemically oxidizing the effluent of step (1), the macromolecular organic matter is converted into small molecular organic matter by ring-opening and chain-breaking, and the molecular structure of the organic matter is changed by addition or substitution of the oxidizing agent, making it easier to be decomposed.

[0018] Preferably, in step (3), the electrochemical anode plate of the electrochemical oxidation treatment is a multi-level pore composite titanium-titanium-based noble metal coating electrode, and the cathode plate is a multi-level pore composite titanium plate or a graphite plate.

[0019] Preferably, the preparation method of the multi-level pore composite titanium-based noble metal coating electrode is:

[0020] 1) The multi-level pore composite titanium plate is pretreated by alkali washing to remove oil and oxalic acid etching;

[0021] 2) The noble metals Ru, Ir, Ta, and Sn are mixed into a coating solution, which is uniformly coated on the pretreated multi-level pore composite titanium plate by a brush, and then dried by infrared rays, pyrolyzed at a high temperature of 450-550°C for 15 min, and the above process is repeated 9 times for coating;

[0022] 3) The graphene is mixed into a coating solution, which is uniformly coated on the multi-level pore composite titanium plate coated with noble metals by a brush, and then dried by infrared rays, pyrolyzed at a high temperature of 450-550°C for 15 min, and the above process is repeated 4 times for coating;

[0023] 4) Finally, pyrolyze at a high temperature of 450-550°C for 1 h.

[0024] Preferably, in step (3), the multi-level pore composite titanium plate is prepared by film forming and high temperature sintering, specifically by: loading titanium alloy powder into a mold, pressing into a green compact by a press, and then sintering at a high temperature of 1100-1300°C, which has the characteristics of high dispersion active sites and multi-dimensional pores.

[0025] Through the effluent of step (2) passing through the electrochemical reaction zone, under the action of the electromagnetic field, the organic matter directly loses electrons on the electrode surface, including electrochemical conversion and electrochemical combustion process, which gradually degrades macromolecular organic matter by dehydrogenation, electrophilic addition, etc. At the same time, strong oxidants such as ·OH, ·O2 - , O3, O - , ·S2O8 2- , Cl2, ClO2, ClO2 - , ClO - , solvated electrons e s , etc. generated on the electrode surface also oxidize and degrade pollutants in wastewater.

[0026] Preferably, in step (4), the ratio of the effluent of step (3) to the effluent of step (2) is 1:1 to 5:1, the concentration of chlorine dioxide and available chlorine in the internal circulation mixed water is controlled below 2 mg / L, and the proportion of particulate and colloidal organic matter is below 50%.

[0027] Through internal circulation mixing, the residual oxidants O3, O- , ·S2O8 2- , Cl2, ClO2, ClO2 - , ClO - , solvated electrons e s , etc. will degrade macromolecular organic matter in pretreated effluent into small molecular organic matter or mineralize into CO2 and H2O;

[0028] Preferably, the intelligent judgment system comprises a chlorine dioxide online detector, an available chlorine online detector, an SCOD online detector and a PLC control system, and the chlorine dioxide online detector, the available chlorine online detector and the SCOD online detector are electrically connected with the PLC control system. By setting the intelligent judgment system for the effluent of step (4), the chlorine dioxide online detector, the available chlorine online detector and the SCOD online detector are included to real-time control the chlorine dioxide concentration, the available chlorine concentration and the SCOD of the effluent of step (4) before entering the biochemical system.

[0029] According to another aspect of the present application, a system for improving the biodegradability of sewage is also provided, which comprises a pretreatment tank, a pre-oxidation tank, an electrochemical reaction tank, a buffer tank and an intelligent judgment system, the pretreatment tank is communicated with the pre-oxidation tank, the pre-oxidation tank is communicated with the electrochemical reaction tank, the electrochemical reaction tank is communicated with the buffer tank, the pre-oxidation tank is communicated with the buffer tank, and the intelligent judgment system is arranged in the buffer tank, which is communicated with a subsequent biochemical system.

[0030] According to the above technical scheme, the present application has the following technical effects:

[0031] 1. The method and system for improving the biodegradability of sewage are widely applicable and can be widely used to improve the biodegradability of high-salt and high-concentration sewage such as high-salt chemical industrial wastewater, petrochemical wastewater, landfill leachate and pharmaceutical wastewater.

[0032] 2. The electrochemical system of the sewage treatment system constructed by the present application has very strong oxidizing property, and the oxidation potential of the anode plate can reach 2.2-2.6V. The electrochemical system specially uses a multi-stage pore composite titanium noble metal coating electrode as an anode plate, and a multi-stage pore composite titanium plate and a graphite plate as cathode plates. In addition to the strong oxidation property of the anode plate and the strong reduction property of the cathode plate for the oxidation-reduction degradation of pollutants, a large amount of ·OH, ·O2 - , O3, O - , ·S2O8 2- , Cl2, ClO2, ClO2 - , ClO - , solvated electrons e s , etc. oxidants can be produced, and this part of oxidants can degrade macromolecular organic matter in sewage into small molecular organic matter or mineralize into CO2 and H2O;

[0033] 3、The present application can eliminate the side effects of electrochemical reaction peroxidation, and significantly improve the biodegradability of sewage. After electrochemical oxidation degradation of organic matter, there is still a high concentration of oxidizing agent remaining in the water. Through system optimization of internal circulation and step (1) effluent pollutants continue to occur redox reaction, not only the residual oxidizing agent is eliminated, but also the pollutants in step (1) effluent are degraded, which greatly improves the biodegradability of sewage.

[0034] 4、The present application constructs a sewage treatment system with high energy utilization rate, large water treatment capacity and low operation cost. Electrochemical reaction has the highest energy consumption in the whole sewage treatment system. The present sewage treatment system effectively utilizes the residual oxidizing agent through optimization of internal circulation, greatly improves the energy utilization rate and sewage treatment capacity, thereby reducing the operation cost of the whole system.

[0035] 5、The intelligent judgment system provided by the present application can adjust the internal circulation amount of the system in real time, effectively ensure the reduction of oxidizing agent, improve the biodegradability of sewage, and is simple to operate and beneficial to system maintenance. BRIEF DESCRIPTION OF DRAWINGS

[0036] Figure 1 is a flow chart of the present application. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the present application more clear and explicit, the following preferred embodiments are combined with the drawings and further described in detail. However, it should be noted that many details in the description are only to make the reader have a thorough understanding of one or more aspects of the present application, and the aspects of the present application can be realized without these specific details.

[0038] Example 1

[0039] In combination Figure 1 As shown in the figure, a method for improving the biodegradability of sewage includes the following steps:

[0040] (1) Pretreatment: double-alkali hardness removal, physical coagulation treatment of sewage, adjusting the pH of sewage to 10, adding a certain amount of sodium carbonate according to the hardness of sewage, adding 150 mg / L of polyaluminum chloride and polyaluminum chloride to the sewage for physical coagulation, so as to remove most of calcium, magnesium, suspended solids and part of macromolecular organic matter through deposition, net capture, adsorption bridging, and electric neutralization;

[0041] (2) Chemical oxidation treatment: chemical oxidation of pretreated sewage by sodium hypochlorite and sodium peroxide, the amount of oxidizing agent is determined by the type and pollutant concentration of the treated sewage;

[0042] (3) Electrochemical oxidation treatment: the wastewater after chemical oxidation is subjected to electrochemical oxidation treatment; the electrochemical anode plate of the electrochemical oxidation treatment is a multi-stage pore composite titanium-based noble metal coating electrode, the cathode plate is a multi-stage pore composite titanium plate or a graphite plate, the multi-stage pore composite titanium plate is prepared by film forming and high-temperature sintering, and has the characteristics of high-dispersed active sites and multi-dimensional pores;

[0043] The preparation method of the multi-stage pore composite titanium-based noble metal coating electrode is as follows:

[0044] 1) The multi-stage pore composite titanium plate is pretreated by alkali cleaning to remove oil and oxalic acid etching;

[0045] 2) The Ru, Ir, Ta and Sn noble metals are matched into a coating liquid, the coating liquid is uniformly coated on the pretreated multi-stage pore composite titanium plate by using a brush, and the coating liquid is dried by infrared rays, pyrolyzed at 500 DEG C for 15 min, and the above process is repeated for 9 times of coating;

[0046] 3) The graphene is matched into a coating liquid, the coating liquid is uniformly coated on the multi-stage pore composite titanium plate coated with noble metals by using a brush, and the coating liquid is dried by infrared rays, pyrolyzed at 500 DEG C for 15 min, and the above process is repeated for 4 times of coating;

[0047] 4) Finally, pyrolysis at 500 DEG C for 1 h is performed;

[0048] The multi-stage pore composite titanium plate is prepared by film forming and high-temperature sintering, specifically as follows: titanium alloy powder is loaded into a mold, a compact is pressed by using a press, and then high-temperature sintering at 1200 DEG C is performed;

[0049] (4) Internal circulation mixing treatment: the ratio of the effluent of step (3) to the effluent of step (2) is 3:1, the chlorine dioxide and available chlorine concentrations of the internal circulation mixed water are controlled to be below 2 mg / L, and the proportion of particulate and colloidal organic matter is below 50%;

[0050] (5) Real-time regulation: a smart judgment system is set, and the chlorine dioxide concentration, available chlorine concentration and SCOD concentration in the effluent of step (4) before entering the biochemical system are regulated in real time according to the smart judgment system.

[0051] The electrochemical system of the sewage treatment system constructed in the embodiment has very strong oxidizing property, and the anode plate oxidation potential can reach 2.6 V. The system of the method for improving the biodegradability of sewage in the embodiment comprises a pretreatment tank, a pre-oxidation tank, an electrochemical reaction tank, a buffer tank and an intelligent judgment system. The pretreatment tank is in communication with the pre-oxidation tank. The pre-oxidation tank is in communication with the electrochemical reaction tank. The electrochemical reaction tank is in communication with the buffer tank. The pre-oxidation tank is in communication with the buffer tank. The intelligent judgment system is arranged in the buffer tank, and the buffer tank is in communication with a subsequent biochemical system. The intelligent judgment system comprises a chlorine dioxide online detector, an available chlorine online detector, an SCOD online detector and a PLC control system. The chlorine dioxide online detector, the available chlorine online detector and the SCOD online detector are electrically connected with the PLC control system.

[0052] Embodiment 2

[0053] A method for improving the biodegradability of sewage, comprising the following steps:

[0054] (1) double-alkali hardness removal, physical and chemical coagulation treatment of sewage, adjusting the pH of the sewage to 8, adding a certain amount of sodium carbonate according to the hardness of the sewage, adding 150 mg / L of polyaluminum chloride and polyaluminum chloride to the sewage for physical and chemical coagulation, so as to remove most of calcium, magnesium, suspended solids and part of macromolecular organic matter through deposition, net capture, adsorption bridging, electric neutralization and the like;

[0055] (2) chemical oxidation treatment: chemical oxidation of the pretreated sewage by hydrogen peroxide and ozone;

[0056] (3) electrochemical oxidation treatment: electrochemical oxidation treatment of the chemically oxidized sewage; the electrochemical anode plate of the electrochemical oxidation treatment is a multi-level pore composite titanium-titanium-based noble metal coating electrode, and the cathode plate is a multi-level pore composite titanium plate or a graphite plate. The multi-level pore composite titanium plate is prepared by film forming and high-temperature sintering, and has the characteristics of high-dispersed active sites and multi-dimensional pores.

[0057] The preparation method of the multi-level pore composite titanium-based noble metal coating electrode is as follows:

[0058] 1) The multi-level pore composite titanium sheet is pretreated by alkali washing to remove oil and oxalic acid etching;

[0059] 2) The Ru, Ir, Ta and Sn noble metals are matched into a coating liquid, the coating liquid is uniformly coated on the pretreated multi-level pore composite titanium sheet by using a brush, and the coating liquid is dried by infrared rays, high-temperature pyrolysis at 500 DEG C for 15 min, and the above process is repeated for 9 times of coating;

[0060] 3) The graphene is prepared into a coating liquid, which is uniformly coated onto the multi-stage pore composite titanium sheet coated with noble metal by using a brush, and is dried by infrared rays, and pyrolysis is carried out at 500 DEG C for 15 min, and the above process is repeated 4 times for coating;

[0061] 4) Finally, pyrolysis is carried out at 500 DEG C for 1 h;

[0062] The multi-stage pore composite titanium sheet is prepared by film forming and high-temperature sintering, and the specific steps are as follows: titanium alloy powder is loaded into a mold, a compact is pressed by using a press, and then high-temperature sintering is carried out at 1200 DEG C;

[0063] (4) Internal circulation mixing treatment: the ratio of the effluent of step (3) to the effluent of step (2) is 1:1, the chlorine dioxide and available chlorine concentrations of the internal circulation mixed water are controlled to be below 2 mg / L, and the proportion of particulate and colloidal organic matter is below 50%;

[0064] (5) Real-time regulation: a smart judgment system is set, and the chlorine dioxide concentration, available chlorine concentration and SCOD concentration in the effluent of step (4) before entering the biochemical system are regulated in real time according to the smart judgment system.

[0065] The oxidation of the electrochemical system of the constructed sewage treatment system is very strong, and the anode plate oxidation potential can reach 2.5V. The system of the method for improving the biodegradability of sewage in the embodiment comprises a pretreatment tank, a pre-oxidation tank, an electrochemical reaction tank, a buffer tank and a smart judgment system. The pretreatment tank is in communication with the pre-oxidation tank, the pre-oxidation tank is in communication with the electrochemical reaction tank, the electrochemical reaction tank is in communication with the buffer tank, the pre-oxidation tank is in communication with the buffer tank, and the smart judgment system is arranged in the buffer tank, which is in communication with a subsequent biochemical system. The smart judgment system comprises a chlorine dioxide online detector, an available chlorine online detector, an SCOD online detector and a PLC control system, and the chlorine dioxide online detector, the available chlorine online detector and the SCOD online detector are electrically connected with the PLC control system.

[0066] Embodiment 3

[0067] A method for improving the biodegradability of sewage, comprising the following steps:

[0068] (1) Double-alkali hardness removal and physicochemical coagulation treatment are performed on the sewage, the pH of the sewage is adjusted to 12, a certain amount of sodium carbonate is added according to the hardness of the sewage, 150 mg / L of polyaluminum chloride and polyaluminum chloride are added for physicochemical coagulation, so as to remove most of calcium, magnesium, suspended solids and part of macromolecular organic matter through deposition, net capture, adsorption, bridging and electric neutralization;

[0069] (2) Chemical oxidation treatment: the pretreated sewage is subjected to chemical oxidation by sodium dichromate and ozone;

[0070] (3) Electrochemical oxidation treatment: the wastewater after chemical oxidation is subjected to electrochemical oxidation treatment; the electrochemical anode plate of the electrochemical oxidation treatment is a multi-stage pore composite titanium-titanium-based noble metal coating electrode; the cathode plate is a multi-stage pore composite titanium plate or a graphite plate, and the multi-stage pore composite titanium plate is prepared by film forming and high-temperature sintering, and has the characteristics of high-dispersed active sites and multi-dimensional pores;

[0071] The preparation method of the multi-stage pore composite titanium-based noble metal coating electrode is as follows:

[0072] 1) The multi-stage pore composite titanium plate is pretreated by alkali cleaning to remove oil and oxalic acid etching;

[0073] 2) The noble metals such as Ru, Ir, Ta and Sn are mixed into a coating liquid, the coating liquid is uniformly coated on the pretreated multi-stage pore composite titanium plate by using a brush, and the coating liquid is dried by infrared rays, pyrolyzed at 500 DEG C for 15 min, and the above process is repeated for 9 times of coating;

[0074] 3) The graphene is mixed into a coating liquid, the coating liquid is uniformly coated on the multi-stage pore composite titanium plate coated with noble metals by using a brush, and the coating liquid is dried by infrared rays, pyrolyzed at 500 DEG C for 15 min, and the above process is repeated for 4 times of coating;

[0075] 4) Finally, pyrolysis at 500 DEG C for 1 h is performed;

[0076] The multi-stage pore composite titanium plate is prepared by film forming and high-temperature sintering, and the specific steps are as follows: titanium alloy powder is loaded into a mold, a compact is pressed by using a press, and then high-temperature sintering at 1200 DEG C is performed;

[0077] (4) Internal circulation mixing treatment: the ratio of the effluent of step (3) to the effluent of step (2) is 5:1, the chlorine dioxide and available chlorine concentrations of the internal circulation mixed water are controlled to be below 2 mg / L, and the particle and colloidal organic matter accounts for less than 50%;

[0078] (5) Real-time regulation: a smart judgment system is set, and the chlorine dioxide concentration, available chlorine concentration and SCOD concentration in the effluent of step (4) before entering the biochemical system are regulated in real time according to the smart judgment system.

[0079] The electrochemical system of the sewage treatment system constructed in the embodiment has very strong oxidizing property, and the anode plate oxidation potential can reach 2.4V. The system of the method for improving the biodegradability of sewage in the embodiment comprises a pretreatment tank, a pre-oxidation tank, an electrochemical reaction tank, a buffer tank and a wisdom judgment system. The pretreatment tank is in communication with the pre-oxidation tank. The pre-oxidation tank is in communication with the electrochemical reaction tank. The electrochemical reaction tank is in communication with the buffer tank. The pre-oxidation tank is in communication with the buffer tank. The wisdom judgment system is arranged in the buffer tank and in communication with a subsequent biochemical system. The wisdom judgment system comprises a chlorine dioxide online detector, an available chlorine online detector, an SCOD online detector and a PLC control system. The chlorine dioxide online detector, the available chlorine online detector and the SCOD online detector are electrically connected with the PLC control system.

[0080] Embodiment 4

[0081] The embodiment is basically the same as embodiment 1, except that the preparation method of the multi-level pore composite titanium-based noble metal coating electrode is as follows:

[0082] 1) The multi-level pore composite titanium sheet is pretreated by alkali washing to remove oil and oxalic acid etching;

[0083] 2) The Ru, Ir and Ta noble metals are mixed into a coating liquid, which is uniformly coated on the pretreated multi-level pore composite titanium sheet by using a brush. The coating liquid is dried by infrared rays, pyrolyzed at 450 DEG C for 15 minutes, and the above process is repeated for 9 times of coating;

[0084] 3) The graphene is mixed into a coating liquid, which is uniformly coated on the multi-level pore composite titanium sheet coated with noble metals by using a brush. The coating liquid is dried by infrared rays, pyrolyzed at 450 DEG C for 15 minutes, and the above process is repeated for 4 times of coating;

[0085] 4) Finally, pyrolysis is carried out at 450 DEG C for 1 hour;

[0086] The multi-level pore composite titanium plate is prepared by film forming and high temperature sintering. Specifically, the titanium alloy powder is loaded into a mold, and a compact is pressed by using a press, and then high temperature sintering is carried out at 1100 DEG C.

[0087] The electrochemical system of the sewage treatment system constructed in the embodiment has very strong oxidizing property, and the anode plate oxidation potential can reach 2.2V.

[0088] Embodiment 5

[0089] The embodiment is basically the same as embodiment 1, except that the preparation method of the multi-level pore composite titanium-based noble metal coating electrode is as follows:

[0090] 1) The multi-level pore composite titanium sheet is pretreated by alkali washing to remove oil and oxalic acid etching;

[0091] 2) The precious metals of Ru, Ir and Ta are prepared into a coating solution, which is uniformly coated onto the pre-processed multi-stage pore composite titanium sheet by a brush, and dried by infrared rays, pyrolyzed at 450°C for 15 min, and the above process is repeated 9 times for coating;

[0092] 3) The graphene is prepared into a coating solution, which is uniformly coated onto the multi-stage pore composite titanium sheet coated with precious metals by a brush, and dried by infrared rays, pyrolyzed at 450°C for 15 min, and the above process is repeated 4 times for coating;

[0093] 4) Finally, pyrolysis is carried out at 450°C for 1 h;

[0094] The multi-stage pore composite titanium plate is prepared by film forming and high-temperature sintering, specifically by the following steps: titanium alloy powder is loaded into a mold, a compact is pressed by a press, and then high-temperature sintering is carried out at 1100°C.

[0095] The electrochemical system of the sewage treatment system constructed in this embodiment has very strong oxidizing property, and the anode plate oxidation potential can reach 2.4V.

[0096] Example 6

[0097] This example is basically the same as example 1, except that the electrochemical anode plate for electrochemical oxidation treatment is commercially available, and the anode plate oxidation potential is 1.3V.

[0098] Application Example 1, Guangdong Pharmaceutical Wastewater Treatment:

[0099] The treatment process is as follows:

[0100] (1) The sewage is pumped to the pretreatment tank by the lifting pump, the pretreatment tank adopts a horizontal flow type partition reaction tank, which is made of carbon steel, with a size of 2m*2m*1.5m, a hydraulic retention time of 30min, and a flow rate of 20cm / s. Liquid alkali, sodium carbonate and high molecular polyaluminum chloride are pumped into the pretreatment tank, and the mixture is fully stirred by a stirrer. The sludge-water mixture is self-flowed into the flocculation tank, polyacrylamide is added in the flocculation tank, and sludge-water separation occurs. The sludge is precipitated in the sedimentation tank, and the calcium, magnesium, suspended solids and colloidal organic matter in the water body are precipitated into sludge, which is pumped to the sludge treatment system.

[0101] (2) The effluent of step (1) is pumped into chlorine dioxide solution for chemical oxidation, which converts large molecular organic matter into small molecular organic matter by ring-opening and chain-breaking, making it easier to be decomposed;

[0102] (3) The effluent of step (2) passes through the electrochemical reaction zone, the anode is a multi-stage pore composite titanium titanium-based precious metal coating electrode, and the cathode plate is a multi-stage pore composite titanium plate. The current density is 300A / m 2The multi-level channel electrode plate, under the action of electromagnetic field, directly loses electrons on the electrode surface of organic matter, including electrochemical conversion and electrochemical combustion process, through dehydrogenation, electrophilic addition and other processes to gradually degrade macromolecular organic matter. At the same time, strong oxidants such as O3, O - , S2O8 2- , Cl2, ClO2, ClO2 - , ClO - , solvated electrons e s , and the like, which are generated by oxidation on the electrode surface, also oxidize and degrade reducing pollutants in the wastewater at the same time;

[0103] (4) The effluent of step (3) and the effluent of step (2) are mixed by internal circulation at a ratio of 2:1, jet aeration stirring, and the hydraulic retention time is 30 min. The effluent ClO2 is 0.1 mg / L, and the residual chlorine is 0.2 mg / L.

[0104] The water quality parameters of the influent are shown in Table 1, and the water quality of the effluent after water treatment is shown in Table 2.

[0105] Table 1: List of water quality parameters of the influent

[0106]

[0107] Table 2: List of water quality of the effluent of the internal circulation system

[0108]

[0109] The steps (1) to (3) are simultaneously performed without internal circulation, and the system effluent water quality is shown in Table 3:

[0110] Table 3: List of water quality of the effluent of the non-circulation system

[0111]

[0112] As shown in Tables 1-3, after the internal circulation system treatment, the B / C ratio increased from 0.12 to 0.42, the wastewater was converted from non-biodegradable water quality to biodegradable (B / C>0.3) water quality, and the SCOD / COD increased from 0.34 to 0.82, effectively improving the biodegradability of the wastewater. The treated wastewater can enter the anaerobic system for further biochemical degradation. Without the internal circulation system treatment, the B / C ratio increased from 0.12 to 0.21, the biodegradability of the wastewater was improved, but it was still non-biodegradable (B / C<0.3) water quality.

[0113] Therefore, the internal circulation of the effluent after electrochemical treatment can significantly improve the biodegradability of the wastewater.

[0114] Application Example 2, treatment of a new material production wastewater in Hunan:

[0115] Treatment process:

[0116] (1) The main pollutants of the wastewater are quinone substances. The wastewater is pumped to the pretreatment tank by the lifting pump, the pretreatment tank adopts the horizontal flow type baffle reaction tank, the material is carbon steel, the specification is 3.5m*3m*1.5m, the hydraulic retention time is 30min, and the flow rate is 20cm / s. Liquid alkali, sodium carbonate and high molecular polymer ferric sulfate are pumped into the pretreatment tank, and the mixture is fully stirred by the stirrer. The sludge-water mixture is self-flowed into the flocculation tank, polyacrylamide is added in the flocculation tank, and sludge-water separation occurs. The sludge is precipitated in the sedimentation tank, and the calcium, magnesium, suspended solids and colloidal organic matter in the water body are precipitated into sludge, which is pumped to the sludge treatment system.

[0117] (2) The effluent of step (1) is pumped into sodium persulfate solution for chemical oxidation, which converts large molecular organic matter into small molecular organic matter by ring-opening and chain-breaking, so that it is more easily decomposed;

[0118] (3) The effluent of step (2) passes through the electrochemical reaction zone, the anode is a multi-stage pore composite titanium-based noble metal coating electrode, and the cathode plate is a multi-stage pore composite titanium plate. The current density is 350A / m 2 . Under the action of the electromagnetic field, the organic matter loses electrons directly on the electrode surface, including electrochemical conversion and electrochemical combustion process, which gradually degrades the large molecular organic matter through dehydrogenation, electrophilic addition, etc. At the same time, the strong oxidants generated on the electrode surface, such as O3, O - , ·S2O8 2- , Cl2, ClO2, ClO2 - , ClO - , solvated electron e s , etc., also oxidize and degrade the pollutants in the solution synchronously;

[0119] (4) The effluent of step (3) is mixed with the effluent of step (2) in a ratio of 3:1 by internal circulation, jet aeration mixing, the hydraulic retention time is 30min, the effluent ClO2 is 0.3mg / L, and the residual chlorine is 0.7mg / L.

[0120] The water quality parameters of the influent are shown in Table 4, and the water quality of the effluent after water treatment is shown in Table 5.

[0121] Table 4: List of water quality parameters of the influent

[0122]

[0123] Table 5: List of system effluent water quality

[0124]

[0125] The operation mode without internal circulation of steps (1) to (3) is carried out synchronously, and the system effluent water quality is shown in Table 6:

[0126] Table 6: Water quality of effluent of non-circulation system

[0127]

[0128] As shown in Table 4, Table 5 and Table 6, after the sewage treatment system, the B / C ratio is increased from 0.18 to 0.49, the sewage is converted from non-biodegradable water quality to biodegradable (B / C>0.3) water quality, the SCOD / COD is increased from 0.30 to 0.63, the biodegradability of the sewage is effectively improved, and the treated sewage can enter the aerobic system for further biochemical degradation. Without the treatment of the internal circulation system, the B / C ratio is increased from 0.18 to 0.27, the biodegradability of the sewage is improved, but it is still non-biodegradable (B / C<0.3) water quality.

[0129] Therefore, the internal circulation of the effluent after the electrochemical treatment can significantly improve the biodegradability of the sewage.

[0130] The sewage of application example 2 is simultaneously subjected to the electrochemical oxidation treatment using the electrochemical anode plate sold on the market of application example 6, and the internal circulation operation mode is performed according to the steps, and the water quality of the system effluent is shown in Table 7:

[0131] Table 7: Water quality of effluent of non-circulation system

[0132]

[0133] As shown in Table 4 and Table 7, after the sewage treatment system, the B / C ratio is increased from 0.18 to 0.49, the sewage is converted from non-biodegradable water quality to biodegradable (B / C>0.3) water quality, the SCOD / COD is increased from 0.30 to 0.63, the biodegradability of the sewage is effectively improved, and the treated sewage can enter the aerobic system for further biochemical degradation. With the circulation system treatment using the electrochemical anode plate sold on the market, the B / C ratio is increased from 0.18 to 0.32, the sewage is converted from non-biodegradable water quality to biodegradable (B / C>0.3) water quality, which is lower than the internal circulation system of application example 2, and the SCOD / COD is only increased from 0.30 to 0.35.

[0134] The above only describes the preferred embodiments of the present application, and it should be noted that those skilled in the art can make some improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered as the protection scope of the present application.

Claims

1. A method for improving the biodegradability of wastewater, characterized in that: Includes the following steps: (1) Pretreatment: The wastewater is subjected to double alkali hardening and physicochemical coagulation treatment; (2) Chemical oxidation treatment: The pretreated wastewater is chemically oxidized using an oxidant; (3) Electrochemical oxidation treatment: The wastewater that has undergone chemical oxidation is subjected to electrochemical oxidation treatment; (4) Internal circulation mixing treatment: The effluent from step (3) and the effluent from step (2) are mixed in a certain proportion through internal circulation treatment; (5) Real-time control: Set up an intelligent judgment system, and adjust the concentration of chlorine dioxide, effective chlorine and SCOD in the effluent before entering the biochemical system in real time according to the intelligent judgment system; In step (3), the electrochemical anode plate of the electrochemical oxidation treatment is a multi-level porous composite titanium-based noble metal coated electrode, and the cathode plate is a multi-level porous composite titanium plate or graphite plate. The oxidation potential of the anode plate can reach 2.2~2.6V. In step (4), the internal circulation mixing process is carried out. The ratio of the effluent from step (3) to the effluent from step (2) is 1:1 to 5:

1. The concentrations of chlorine dioxide and effective chlorine in the internal circulation mixed water are controlled to be below 2 mg / L, and the proportion of particulate and colloidal organic matter is less than 50%.

2. The method for improving the biodegradability of wastewater according to claim 1, characterized in that: In step (1), the dual-alkali hardening treatment specifically involves adjusting the pH of the wastewater to 8-12, adding a certain amount of sodium carbonate according to the hardness of the wastewater, and then adding polyferric and polyaluminum to precipitate the calcium, magnesium and silicates in the wastewater, thereby reducing the hardness of the wastewater.

3. The method for improving the biodegradability of wastewater according to claim 1, characterized in that: In step (1), the physicochemical coagulation treatment specifically involves treating wastewater with a coagulant, wherein the coagulant is one or more of iron salts, aluminum salts, and titanium salts.

4. The method for improving the biodegradability of wastewater according to claim 3, characterized in that: In step (2), the oxidant is one or more of sodium hypochlorite, sodium chlorite, chlorine dioxide, sodium peroxide, ozone, and hydrogen peroxide.

5. The method for improving the biodegradability of wastewater according to claim 1, characterized in that: In step (3), the preparation method of the multi-level porous composite titanium-based noble metal coated electrode is as follows: 1) Pre-treatment of multi-level porous composite titanium sheets by alkaline washing to remove oil and oxalic acid etching. 2) Prepare a coating solution by mixing Ru, Ir, Ta and Sn noble metals. Apply the coating solution evenly to the pretreated multi-level porous composite titanium sheet with a brush. Dry it with infrared radiation and pyrolyze it at 450-550℃ for 15 minutes. Repeat this process 9 times. 3) Prepare a coating solution with graphene, apply the coating solution evenly to the multi-level porous composite titanium sheet that has been coated with precious metal with a brush, dry it with infrared light, pyrolyze it at 450-550℃ for 15 minutes, and repeat the coating process 3-5 times. 4) Finally, pyrolyze at 450-550℃ for 1 hour.

6. The method for improving the biodegradability of wastewater according to claim 1, characterized in that: In step (3), the multi-level porous composite titanium plate is prepared by coating molding and high-temperature sintering. Specifically, the steps are as follows: titanium alloy powder is loaded into a mold, pressed into a blank by a press, and then sintered at a high temperature of 1100-1300℃, which has the characteristics of highly dispersed active sites and multi-dimensional pores.

7. The system for improving the biodegradability of wastewater according to any one of claims 1-5, characterized in that: The system includes a pretreatment tank, a pre-oxidation tank, an electrochemical reaction tank, a buffer tank, and an intelligent judgment system. The pretreatment tank is connected to the pre-oxidation tank, the pre-oxidation tank is connected to the electrochemical reaction tank, the electrochemical reaction tank is connected to the buffer tank, the pre-oxidation tank is connected to the buffer tank, and the intelligent judgment system is located in the buffer tank, which is connected to the subsequent biochemical system.

8. The system for improving the biodegradability of wastewater according to claim 7, characterized in that: The intelligent judgment system includes an online chlorine dioxide detector, an online available chlorine detector, an online SCOD detector, and a PLC control system. The online chlorine dioxide detector, the online available chlorine detector, and the online SCOD detector are electrically connected to the PLC control system.

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