Drilling waste cascade degradation treatment system and method based on electrochemical in-situ synthesis of H2O2

Abstract

The invention belongs to the technical field of waste treatment, and relates to a well drilling waste cascade degradation treatment system and method based on electrochemical in-situ synthesis of H2O2. The drilling waste cascade degradation treatment method based on electrochemical in-situ synthesis of H2O2 comprises the following steps: adding an iron-based coagulant into drilling fluid waste slurry, and stirring to form a floccule system; h2O2 is produced in situ by adopting an electrochemical synthesis reactor, and a H2O2 solution is obtained; putting the H2O2 solution into the floccule system in batches, stirring for reaction, adding calcium oxide, and performing solid-liquid separation after the reaction is stopped to obtain a mud cake; and adding a microbial liquid to the mud cake, and reacting to obtain the drilling waste meeting the emission standard. According to the method, high-concentration H2O2 is synthesized in situ by utilizing an electrochemical technology, a two-stage physicochemical process is adopted, primary degradation of the polysulfonate drilling waste is realized through multifunctional gradient utilization of an iron-based coagulant, and finally, the waste is deeply degraded by combining a microbial degradation effect.

Description

Technical Field

[0001] The present invention belongs to the technical field of waste treatment, and relates to a drilling waste cascade degradation treatment system and method based on electrochemical in-situ synthesis of H2O2, and in particular to a synergistic treatment technology that self-supplies oxidants through cathode oxygen reduction reaction, combined with coagulation pretreatment-H2O2 oxidation-biological deep degradation. Background Art

[0002] With growing awareness of environmental protection in the oil industry, the discharge of drilling waste and the resulting environmental pollution are attracting increasing attention. Pollutants in drilling waste primarily come from water-soluble additives in drilling fluids, which are characterized by complex pollutant composition, high concentration, high chroma, and high COD values. During the drilling process, different drilling fluid systems are required as the depth changes. The introduction of different drilling fluid additives results in significant variations in the composition of pollutants in the drilling wastewater generated during the drilling process. Deep gas field drilling (above 5,000 m) often uses polysulfonated drilling fluids, which contain alkali, polymers, lubricants, sulfonated lignite (SMC), sulfonated phenolic resin (SMP), sulfonated asphalt (SAS), inhibitors, sodium silicate, humic acid, and plugging agents. According to research, the polysulfone drilling fluid system is currently mainly used for deep well operations, among which a large number of high-temperature resistant sulfonated materials are used. Its main characteristics are high water-soluble COD value and large chroma. The COD value of the polysulfone drilling fluid at the current operation site is usually greater than 20,000 mg / L. After flocculation and filtration, the COD value of the filter cake is usually greater than 200 mg / L, which cannot meet the government emission standards.

[0003] Common treatment technologies both domestically and internationally include solid-liquid separation, solidification, flotation, advanced oxidation (Fenton, subcritical oxidation), and biocomposting. Solid-liquid separation involves adding breakers and flocculants (iron-based coagulants are typical coagulants, which not only act as coagulation but also as catalysts for advanced oxidation) to the waste mud. This leads to chemical reactions that alter the slurry's properties, disrupting its stable colloidal system and causing small particles and suspended matter to form larger flocs. Mechanical centrifugation, filter presses, and other methods are then used to separate the solid and liquid phases. However, using this technology alone generally exhibits selectivity for organic matter, making it difficult to achieve pollutant emission standards. Therefore, it is often coupled with other technologies. Solidification involves adding an appropriate proportion of chemical additives and a solidifying agent to the drilling fluid and thoroughly mixing them. This destabilizes and dehydrates the drilling fluid. The solidifying agent undergoes a vigorous hydration reaction with the water in the drilling fluid, crosslinking and flocculating with organic matter and solid particles, forming a solid-solidifying agent-water hydrated flocculation system. Through self-cementation and encapsulation, the system gradually transforms into an irreversible solid phase. The resulting solidified product exhibits water resistance, encapsulation, and adsorption properties, thereby restricting the flow of drilling waste fluids and inhibiting the migration and diffusion of their components. While solidification methods offer rapid treatment speed and excellent results, they lack adaptability and require on-site experimental adjustments to the solidification formula, which is inconvenient, time-consuming, and impacts the construction process. Flotation is a commonly used drilling waste fluid treatment technology. It uses aeration to create highly dispersed microbubbles in water, which adhere to hydrophobic solid or liquid particles in the wastewater, forming a three-phase water-air-particle system. Once adhered to the bubbles, the particles form flocs with an apparent density less than that of water, floating to the surface and forming a scum layer that is scraped off. This reduces the COD content of the final mud cake by migrating and / or degrading organic matter throughout the base fluid. For drilling waste fluids with high water content and high emulsification, flotation can complement chemical solid-liquid separation water treatment technologies. However, this technology still suffers from drawbacks such as high energy consumption, large footprint, unsuitability for high-solids fluids, and susceptibility to aeration port clogging. Advanced oxidation technology (Fenton process) relies on Fe²⁺-catalyzed decomposition of H₂O₂ to generate OH, which then oxidizes and degrades difficult-to-degrade organic matter. This technology uses hazardous chemicals and presents significant safety risks during transportation and storage. Advanced oxidation technology (subcritical oxidation) uses oxygen in the subcritical state of water to degrade organic matter in wastewater into harmless substances such as CO₂, H₂O, and N₂, significantly reducing COD. However, subcritical conditions place high demands on equipment, resulting in complex process flows and difficulty controlling the subcritical state. Biocomposting, which uses microorganisms to completely mineralize organic matter, has a lengthy cycle, significant environmental impact, uncontrollable results, and requires significant floor space.

[0004] Advanced oxidation technology based on electrochemical catalytic oxygen reduction reaction has attracted much attention due to its high efficiency and environmental protection characteristics. This technology uses oxygen (even ordinary air) to synthesize H2O2 in situ at room temperature and normal pressure through electrochemical reaction. The reaction process is simple and does not require complex conditions. As a strong oxidant, H2O2 can produce hydroxyl radicals (·OH) through various pathways (such as photolysis, catalytic decomposition, etc.). ·OH is an active oxygen species with extremely high oxidation potential. It can non-selectively degrade a variety of organic matter and plays a key role in the advanced oxidation process. In practical applications, ferrous ions (Fe 2+ ) as a catalyst is a typical advanced oxidation technology. 2+ The catalytic decomposition of H₂O₂ to form ·OH exhibits excellent degradation of pollutants in drilling fluid wastewater. This technology not only has mild reaction conditions but can also effectively treat high-concentration, highly toxic organic wastewater. However, this method still faces certain limitations in practical application. As a strong oxidant, H₂O₂ poses a high safety risk during transportation and storage, requiring strict protective measures. Furthermore, the applicability of this technology needs to be further expanded. For certain high-COD wastes, Fenton oxidation alone is difficult to achieve complete degradation of pollutants and may not meet stringent emission standards. Physicochemical-biochemical coupled treatment technology is a particularly suitable treatment method for onshore drilling platforms. Using one or more physicochemical processes, refractory organic pollutants in drilling waste are pre-oxidized, breaking them down into biodegradable small molecules. Combined with biochemical treatment, which leverages microbial metabolism to deeply remove residual organic matter from drilling waste, this method can improve treatment efficiency and significantly reduce chemical reagent costs.

[0005] In the prior art, as described in a patent for a harmless deep treatment method for water-based drilling fluid solid-liquid waste (Application Number: CN202111579505.4), a mud is first separated from oil and water. The mud is then mixed with a gel breaker and a flocculant, and subjected to a second solid-liquid separation to obtain a second liquid phase and a second solid phase. The second liquid phase is then treated with water to produce wastewater that meets discharge standards and a third solid phase. The patent utilizes a combined process for the water treatment of the second liquid phase, including flotation, coagulation, and electrochemical oxidation. The process flow and stages in this patent are overly complex. This patent innovatively proposes adding a coagulant to the drilling waste mud before directly performing electrochemical oxidation. This significantly differs from the comparative patent, simplifying the treatment process, enabling the gradient utilization of an iron-based coagulant, initial oxidation of the drilling waste, and improving the biodegradability of the mud cake. A patented biocomposting method for oil-based drilling waste (application number: CN2014100391397) screens bacterial strains capable of efficiently degrading petroleum hydrocarbons from oil-based drilling waste. These strains are then formulated into a solid composite inoculant through orthogonal experiments. The solid composite inoculant is then added to the oil-based drilling waste and mixed with rice bran as a support to create a compost pile. The carbon-nitrogen ratio and moisture content of the compost pile are then adjusted, and after turning, sampling, and analysis, on-site composting is completed. After one month of treatment, the degradation rate of total petroleum hydrocarbons in the oil-based drilling waste can reach over 80%. The method described in this patent takes a long time to process, making it difficult to achieve a large accumulation of pollutants. Furthermore, the method relies solely on microbial degradation of organic matter within the waste. However, the functional inoculant selected in this patent achieves effective degradation within five days, improving degradation efficiency. It also achieves a gradient degradation of organic matter and achieves deep degradation of simple organic matter that has undergone physicochemical treatment. Summary of the Invention

[0006] The purpose of the present invention is to address the defects of the prior art and provide a drilling waste cascade degradation treatment system and method based on electrochemical in-situ synthesis of H2O2.

[0007] Specifically, the present invention provides a method for treating drilling waste by cascade degradation based on electrochemical in-situ synthesis of H2O2, comprising: (1) Add an iron-based coagulant to the waste drilling mud and stir to form a flocculent system; (2) Using an electrochemical synthesis reactor to produce H2O2 in situ to obtain H2O2 solution; (3) adding the H2O2 solution into the flocculent system of step (1) in batches, stirring to react, adding calcium oxide, and performing solid-liquid separation after the reaction stops to obtain a mud cake; (4) Adding microbial liquid to the mud cake, and reacting to obtain drilling waste that meets the discharge standards.

[0008] In the above-mentioned method for cascade degradation treatment of drilling waste based on electrochemical in-situ synthesis of H2O2, the iron-based coagulant is one or more of ferrous sulfate, ferric sulfate, polyferric sulfate, ferric chloride, and polyferric chloride.

[0009] In the above-mentioned drilling waste cascade degradation treatment method based on electrochemical in-situ synthesis of H2O2, the weight ratio of the iron-based coagulant to the drilling fluid waste mud volume is (4g~10g):100mL.

[0010] The above-mentioned drilling waste cascade degradation treatment method based on electrochemical in-situ synthesis of H2O2, step (2) includes: using a calcined carbon black-graphite-PTFE air breathing cathode as the cathode and a titanium / iridium dioxide composite metal plate as the anode, passing a 1~2 M NaOH electrolyte into the anode chamber, passing a 50 mM~1 M Na2SO4 electrolyte into the cathode chamber, controlling the current to 4.8~14.4 A, passing an oxygen flow rate of 50~200 mL / min, and reacting for 6~15 hours to generate a 3~6% H2O2 solution.

[0011] In the above-mentioned method for cascade degradation treatment of drilling waste based on electrochemical in-situ synthesis of H2O2, in step (3), the volume of the H2O2 solution is 5% to 20% of the volume of the drilling fluid waste mud, and the stirring reaction time is 0.5 to 1.5 h; the mass of the calcium oxide powder is 2% to 5% of the weight of the drilling fluid waste mud.

[0012] In the above-mentioned cascade degradation treatment method for drilling waste based on electrochemical in-situ synthesis of H2O2, the microbial bacterial solution is an aqueous solution of Acinetobacter venetianus RAG-1 with an OD600 of 1.8-2.8.

[0013] In the above-mentioned cascade degradation treatment method for drilling waste based on electrochemical in-situ synthesis of H2O2, the microbial liquid is 10-30% of the volume increment of the mud cake.

[0014] In the above-mentioned method for cascade degradation of drilling waste based on electrochemical in-situ synthesis of H2O2, in step (4), the reaction time is 4 to 8 days.

[0015] In the above-mentioned drilling waste cascade degradation treatment method based on electrochemical in-situ synthesis of H2O2, the COD of the leachate of the drilling waste that meets the emission standards is ≤150 mg / L.

[0016] The present invention provides a drilling waste cascade degradation treatment system based on electrochemical in-situ synthesis of H2O2, comprising: Drilling fluid waste mud collection tank 1; Coagulation tank 2, connected to the drilling fluid waste mud collection tank 1, used for iron-based coagulant pretreatment; H2O2 electrochemical synthesis device 3, the output end of which is connected to the coagulation tank 2; Plate and frame filter press 4, for solid-liquid separation; The microbial agent supply unit 5 sprays the bacterial solution onto the mud cake after filtration; The biochemical treatment unit 6 is used for microbial oxidation reaction.

[0017] The above-mentioned drilling waste cascade degradation treatment system based on electrochemical in-situ synthesis of H2O2, the H2O2 electrochemical synthesis device 3 includes: a cathode chamber comprising a cathode formed by a stacked arrangement of air-breathing cathode units; an anode chamber comprising an anode consisting of a titanium / iridium dioxide anode plate; An ion exchange membrane is used to separate the anode chamber and the cathode chamber.

[0018] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: (1) This invention utilizes electrochemical technology to synthesize high-concentration H2O2 in situ. It employs a two-stage physicochemical process, namely coagulation and H2O2 oxidation, to achieve initial degradation of polysulfonated drilling waste through the multifunctional gradient utilization of an iron-based coagulant. Finally, microbial degradation is combined to achieve deep degradation of the waste. The complex organic matter in the polysulfonated drilling waste is completely mineralized after a step-by-step degradation process, and the COD of the filter cake leachate is less than 150 mg / L (DB65 / T 3997-2017), meeting the emission standards.

[0019] (2) The present invention avoids the transportation and storage safety issues of hazardous chemicals through the in-situ electrochemical synthesis of H2O2. The gradient utilization of iron-based coagulants can reduce the dosage of reagents and improve the degradation efficiency. After gradient degradation through coupled technology, the waste can be discharged in a short time and meet the discharge standards, which is more suitable for industrial field operations and ultimately realizes the safe and green treatment of polysulfone drilling waste.

[0020] (3) The present invention innovatively achieves synergistic efficiency through the physicochemical-biochemical coupling mechanism of the gradient utilization of iron-based coagulants and the in-situ synthesis of oxidants. Combined with the electrochemical H2O2 production and use technology, it avoids the storage and transportation loss of oxidants, drives the efficient degradation of large molecular pollutants by OH, and forms a "physicochemical fragmentation-biomineralization" degradation closed loop. In practical applications, COD can be reduced to as low as 108 mg / L, and the treatment cycle is as short as 5 days. It has an effective effect on a variety of polysulfone drilling fluid wastes. During the implementation of the present invention, no strong acid or strong base is added, and the final product stably meets the national secondary emission standards, providing a green and efficient solution for the treatment of polysulfone drilling waste. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Various other advantages and benefits will become apparent to those skilled in the art by reading the following detailed description of the preferred embodiment.The accompanying drawings are only for the purpose of illustrating the preferred embodiment and are not to be considered as limiting the present invention.

[0022] Figure 1 Schematic diagram of the drilling waste cascade degradation treatment system based on electrochemical in-situ synthesis of H2O2 according to the present invention.

[0023] Figure 2 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 1.

[0024] Figure 3 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 2.

[0025] Figure 4 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 3.

[0026] Figure 5 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 4.

[0027] Figure 6 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 5.

[0028] Figure 7 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 6.

[0029] Figure 8 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 7.

[0030] Figure 9 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 8.

[0031] Figure 10 It is the COD concentration during the cascade degradation treatment of drilling waste in Example 9. DETAILED DESCRIPTION

[0032] In order to fully understand the purpose, features and effects of the present invention, the present invention is described in detail through the following specific embodiments. Except for the following contents, the process of the present invention adopts conventional methods or devices in the art. Unless otherwise specified, the following terms have the meanings commonly understood by those skilled in the art.

[0033] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between such minimum and maximum values. Further, when a range refers to an integer, every integer between the minimum and maximum values ​​of the range is included. In addition, when multiple ranges are provided to describe a feature or characteristic, the ranges can be combined. In other words, unless otherwise indicated, all ranges disclosed herein are understood to include any and all subranges subsumed therein.

[0034] The concept of the present invention is to overcome the technical defects of existing treatment methods such as low degradation efficiency, high reagent cost, secondary pollution risk, and restrictions on the use of hazardous chemicals by electrochemical in situ synthesis of high-concentration H2O2, combined with the synergistic technology of coagulation-H2O2 oxidation coupling microbial oxidation, to achieve complete degradation of polysulfone drilling waste and deep degradation of polysulfone drilling fluid waste, so that the COD of the filter cake is ≤150 mg / L (DB65 / T 3997-2017), meeting the emission standards.

[0035] Specifically, the present invention provides a method for treating drilling waste by cascade degradation based on electrochemical in-situ synthesis of H2O2, comprising: (1) Iron-based coagulation pretreatment Add iron-based coagulant to the waste drilling fluid slurry and stir it until a large amount of floccules appear, then stop stirring.

[0036] In some preferred embodiments, the iron-based coagulant is one or more of ferrous sulfate, ferric sulfate, polyferric sulfate, ferric chloride, and polyferric chloride, and is more preferably ferrous sulfate.

[0037] In some preferred embodiments, the weight ratio of the iron-based coagulant to the drilling fluid waste mud volume is (4g-10g):100mL.

[0038] (2) Electrochemical in situ synthesis of H2O2 An electrochemical synthesis reactor is used to produce H2O2 in situ to obtain a H2O2 solution.

[0039] In some preferred embodiments, the electrochemical in situ synthesis of H2O2 uses a calcined carbon black-graphite-PTFE air breathing cathode as the cathode and a titanium / iridium dioxide composite metal plate as the anode. A 1~2 M NaOH electrolyte is introduced into the anode chamber, and a 50 mM~1 M Na2SO4 electrolyte is introduced into the cathode chamber. The current is controlled at 4.8~14.4 A, an oxygen flow rate of 50~200 mL / min, and the reaction is carried out for 6~15 hours to generate a 3~6% H2O2 solution.

[0040] (3) H2O2 oxidation treatment The H2O2 solution is added to the flocculent system of step (1) in batches, stirred for reaction, and calcium oxide is added. After the reaction stops, solid-liquid separation is performed to obtain a mud cake.

[0041] In some preferred embodiments, the volume of the H2O2 solution is 5-20% of the volume of the waste drilling fluid slurry, and the stirring reaction time is 0.5-1.5 h.

[0042] The present invention removes most of the silicides through a flocculation+oxidation process and oxidizes long-chain hydrocarbons into short-chain hydrocarbons, thereby improving the biodegradability of organic matter in the mud cake.

[0043] By adding CaO, the pH of the mud can be increased, which can promote the 2+ The calcium oxide powder is converted into FeOOH colloid, which has both coagulation and catalytic activity carrier functions. In some preferred embodiments, the mass of the calcium oxide powder is 2% to 5% of the weight of the drilling fluid waste mud.

[0044] (4) Microbial oxidation treatment Microbial liquid is added to the mud cake by spraying or the like, and after reaction for 4 to 8 days, drilling waste with a leachate having a COD of ≤150 mg / L is obtained.

[0045] In some preferred embodiments, the microbial liquid is an aqueous solution of Acinetobacter venetianus RAG-1, and the OD600 is 1.8-2.8, more preferably 2.5.

[0046] In some preferred embodiments, the microbial liquid is 10-30% of the volume increment of the mud cake.

[0047] The “volume increment” refers to the ratio of the volume of the microbial solution added to the volume of the mud cake itself. For example, if the microbial solution is 10-30% of the volume increment of the mud cake, it means that 1 m 3 Mud cake added 0.1 m 3 ~ 0.3 m 3 of bacterial liquid.

[0048] On the other hand, Figure 1 As shown, the present invention also provides a drilling waste cascade degradation treatment system based on electrochemical in-situ synthesis of H2O2, comprising: Drilling fluid waste mud collection tank 1; Coagulation tank 2, connected to the drilling fluid waste mud collection tank 1, used for iron-based coagulant pretreatment; H2O2 electrochemical synthesis device 3, the output end of which is connected to the coagulation tank 2; Plate and frame filter press 4, for solid-liquid separation; The microbial agent supply unit 5 sprays the bacterial solution onto the mud cake after filtration; The biochemical treatment unit 6 is used for microbial oxidation reaction.

[0049] In some preferred embodiments, the main body of the H2O2 electrochemical synthesis device 3 is made of organic glass and includes: a cathode chamber comprising a cathode formed by a stacked arrangement of air-breathing cathode units; an anode chamber comprising an anode consisting of a titanium / iridium dioxide anode plate; An ion exchange membrane is used to separate the anode chamber and the cathode chamber.

[0050] In some preferred embodiments, the cathode chamber volume is 1.5 L, the cathode is a calcined carbon black-graphite-PTFE air breathing cathode, and the electrode area is 320-480 cm 2 The cathode area of ​​a single electrode group is 80 cm 2 The anode chamber volume is 1 L, the anode is 4 titanium / iridium dioxide composite metal plates with dimensions of 4 cm * 10 cm * 1 mm, and the ratio of iridium dioxide coating mass to titanium plate area is 10 g / m 2 .

[0051] The air-breathing cathode unit group is embedded in the cathode chamber reaction tank, and is arranged alternately in positive and negative directions to form an S-shaped corridor. An anode plate insertion slot is set above the anode chamber for placing the anode plates.

[0052] In some preferred embodiments, the size of the ion exchange membrane is 5 cm*5 cm, and the model is CAM-1680.

[0053] This invention proposes for the first time a coupled coagulation, electrochemical oxidation, and biodegradation technology based on the in-situ electrochemical synthesis of high-concentration H₂O₂. This innovative technology utilizes in-situ electrochemical synthesis of high-concentration H₂O₂ for the oxidative degradation of polysulfone drilling waste, achieving a multifunctional, gradient utilization of the iron-based coagulant (i.e., performing coagulant functions in the coagulation phase and catalyst functions in the oxidation phase). Furthermore, through the physicochemical treatment phase, the invention transforms complex organic matter into simple organic matter that can be utilized by microorganisms. Ultimately, microbial metabolism leads to complete mineralization, achieving a cascaded degradation of organic matter in drilling waste.

[0054] Example The present invention is further illustrated by way of examples below, but the invention is not limited to the scope of the examples. The experimental methods in the following examples where specific conditions are not specified were based on conventional methods and conditions. The raw materials used in the following examples were all commercially available.

[0055] Example 1 This example deals with the waste of polysulfone drilling fluid generated in the upper well section of 8 1 / 2". Figure 2 The COD of the untreated mud cake leachate is shown to be approximately 1052 mg / L.

[0056] (1) Add 3 g of ferrous sulfate to 50 mL (62.5 g) of the generated waste to cause a coagulation reaction; (2) Add 1 L of 2 M NaOH electrolyte to the anode chamber of the electrochemical synthesis reactor and 1.5 L of 1 M Na2SO4 electrolyte to the cathode chamber. Place four Ti / IrO2 anode plates (size: 4 cm * 10 cm * 1 mm, with a ratio of iridium dioxide coating mass to titanium plate area of ​​10 g / m 2 ) was connected to the positive terminal of a DC power supply. The cathode plates (14 cm * 2 cm * 6 cm) in each of the six air-breathing cathode units were connected to the negative terminal of the DC power supply, with the DC power supply current controlled at 9.6 A. Oxygen was introduced from an oxygen cylinder through a burst needle into the sealed chambers of the six air-breathing cathode units at a flow rate of 150 mL / min. Samples were taken at fixed points every hour, and the hydrogen peroxide concentration was determined using potassium titanium oxalate spectrophotometry. The reactor was operated for 11 hours to synthesize a 5% H2O2 solution.

[0057] (3) 5 mL of the H2O2 solution prepared in step (2) was added to the mud after coagulant treatment in two batches. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing. The COD of the mud cake leachate after the two-stage physical and chemical treatment was measured to be reduced to 211 mg / L.

[0058] (4) After testing, the moisture content of the mud cake is about 25% and the density is about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus For RAG-1, the ratio of mud cake mass to bacterial solution volume was 5 g:1 mL (the bacterial solution volume increment was 25%). The mixture was placed in a 35°C incubator and reacted for 5 days. The mud cake moisture content was less than 25%, and the COD of the leachate further decreased to 114 mg / L, ultimately meeting the discharge standard.

[0059] Example 2 This example deals with the waste of polysulfone drilling fluid generated in the upper section of the 8 1 / 2" well. Figure 3The COD of the untreated mud cake leachate is shown to be about 1052 mg / L. First, 3 g of ferrous sulfate was added to the generated 50 mL (62.5 g) of waste to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 was added to the mud treated with the coagulant. The H2O2 solution was added twice. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing, and the COD of the mud cake leachate after two stages of physical and chemical treatment was measured to be reduced to 211 mg / L. A microbial culture with an OD600 of about 2.5 was added to the mud cake. Acinetobacter venetianus RAG-1, with a sludge cake mass to bacterial solution volume ratio of 5 g:1 mL (with a 25% bacterial solution volume increment), was placed in an incubator at 25°C. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 128 mg / L, ultimately meeting discharge standards.

[0060] Example 3 This example deals with the waste of polysulfone drilling fluid generated in the upper section of the 8 1 / 2" well. Figure 4 The COD of the untreated mud cake leachate is shown to be about 1052 mg / L. First, 3 g of ferrous sulfate was added to the 50 mL (62.5 g) of waste generated to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 was added to the mud treated with the coagulant. The H2O2 solution was added twice. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing, and the COD of the mud cake leachate after two stages of physical and chemical treatment was measured to be reduced to 211 mg / L. After testing, the moisture content of the mud cake was about 25% and the density was about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus RAG-1, with a sludge cake mass to bacterial solution volume ratio of 5 g:1 mL (with a 25% bacterial solution volume increment), was placed in an incubator at 15°C. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 136 mg / L, ultimately meeting discharge standards.

[0061] Example 4 This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 5The COD of the untreated mud cake leachate is shown to be about 1185 mg / L. First, 3 g of ferrous sulfate was added to the generated 50 mL (62.5 g) of waste to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 was added to the mud treated with the coagulant. The H2O2 solution was added twice. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing, and the COD of the mud cake leachate after two stages of physical and chemical treatment was measured to be reduced to 226 mg / L. After testing, the moisture content of the mud cake was about 25% and the density was about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus RAG-1, with a sludge cake mass to bacterial solution volume ratio of 5 g:1 mL (with a 25% bacterial solution volume increment), was placed in a 35°C incubator. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 120 mg / L, ultimately meeting discharge standards.

[0062] Example 5 This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 6 The COD of the untreated mud cake leachate is shown to be about 1185 mg / L. First, 3 g of ferrous sulfate was added to the generated 50 mL (62.5 g) of waste to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 was added to the mud treated with the coagulant. The H2O2 solution was added twice. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing, and the COD of the mud cake leachate after two stages of physical and chemical treatment was measured to be reduced to 226 mg / L. After testing, the moisture content of the mud cake was about 25% and the density was about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus RAG-1, with a sludge cake mass to bacterial solution volume ratio of 5 g:1 mL (with a 25% bacterial solution volume increment), was placed in an incubator at 25°C. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 128 mg / L, ultimately meeting discharge standards.

[0063] Example 6 This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 7The COD of the untreated mud cake leachate is shown to be about 1185 mg / L. First, 3 g of ferrous sulfate was added to the generated 50 mL (62.5 g) of waste to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 was added to the mud treated with the coagulant. The H2O2 solution was added twice. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing, and the COD of the mud cake leachate after two stages of physical and chemical treatment was measured to be reduced to 226 mg / L. After testing, the moisture content of the mud cake was about 25% and the density was about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus RAG-1, with a sludge cake mass to bacterial solution volume ratio of 5 g:1 mL (with a 25% bacterial solution volume increment), was placed in an incubator at 15°C. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 136 mg / L, ultimately meeting discharge standards.

[0064] Example 7 This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 8 The COD of the untreated mud cake leachate is shown to be about 1326 mg / L. First, 3 g of ferrous sulfate was added to the generated 50 mL (62.5 g) of waste to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 was added to the mud treated with the coagulant. The H2O2 solution was added twice. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing, and the COD of the mud cake leachate after two stages of physical and chemical treatment was measured to be reduced to 249 mg / L. After testing, the moisture content of the mud cake was about 25% and the density was about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus For RAG-1, the sludge cake mass to bacterial solution volume ratio was 5 g:1 mL (with a 25% bacterial solution volume increment), and the mixture was placed in a 35°C incubator. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 108 mg / L, ultimately meeting discharge standards.

[0065] Example 8 This example deals with the waste of polysulfone drilling fluid generated in the 8 1 / 2" downhole section. Figure 9The COD of the untreated mud cake leachate is shown to be about 1326 mg / L. First, 3 g of ferrous sulfate was added to the generated 50 mL (62.5 g) of waste to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 was added to the mud treated with the coagulant. The H2O2 solution was added twice. After a period of reaction, 2.5 g of calcium oxide powder was added. The mud was separated into solid and liquid by filter pressing. The COD of the mud cake leachate after the two-stage physical and chemical treatment was measured to be reduced to 249 mg / L. After testing, the moisture content of the mud cake was about 25% and the density was about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus RAG-1, with a sludge cake mass to bacterial solution volume ratio of 5 g:1 mL (with a 25% bacterial solution volume increment), was placed in an incubator at 25°C. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 115 mg / L, ultimately meeting discharge standards.

[0066] Example 9 This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 10 The COD of the untreated mud cake leachate is about 1326 mg / L. First, 3 g of ferrous sulfate is added to 50 mL (62.5 g) of the generated waste to cause a coagulation reaction. Then, 5 mL of H2O2 solution prepared according to the method of Example 1 is added to the mud treated with the coagulant. The H2O2 solution is added twice, and after a period of reaction, 2.5 g of calcium oxide powder is added. The mud is separated into solid and liquid by filter pressing, and the COD of the mud cake leachate after two stages of physical and chemical treatment is measured to be reduced to 249 mg / L. After testing, the moisture content of the mud cake is about 25%, and the density is about 1.25 kg / m 3 , the volume of 5g mud cake is about 4cm 3 Add microbial solution with OD600 of about 2.5 to the mud cake Acinetobacter venetianus RAG-1, with a sludge cake mass to bacterial solution volume ratio of 5 g:1 mL (with a 25% bacterial solution volume increment), was placed in an incubator at 15°C. After five days of reaction, the sludge cake moisture content was below 25%, and the COD content of the leachate further decreased to 121 mg / L, ultimately meeting discharge standards.

[0067] The present invention has been disclosed above with reference to preferred embodiments. However, those skilled in the art will appreciate that these embodiments are intended only to illustrate the present invention and are not to be construed as limiting the scope of the present invention. It should be noted that any equivalent variations and substitutions to these embodiments are to be considered encompassed within the scope of the claims of the present invention. Therefore, the scope of protection of the present invention shall be subject to the scope defined in the claims.

Claims

1. A drilling waste cascade degradation treatment method based on electrochemical in-situ synthesis of H2O2, characterized in that: include: (1) Add an iron-based coagulant to the waste drilling mud and stir to form a flocculent system; (2) Using an electrochemical synthesis reactor to produce H2O2 in situ to obtain H2O2 solution; (3) adding the H2O2 solution into the flocculent system of step (1) in batches, stirring to react, adding calcium oxide, and performing solid-liquid separation after the reaction stops to obtain a mud cake; (4) Adding microbial liquid to the mud cake, and reacting to obtain drilling waste that meets the discharge standards.

2. The processing method according to claim 1, characterized in that The iron-based coagulant is one or more of ferrous sulfate, ferric sulfate, polyferric sulfate, ferric chloride, and polyferric chloride.

3. The processing method according to claim 1, characterized in that The weight ratio of the iron-based coagulant to the volume of the drilling fluid waste mud is (4g~10g):100mL.

4. The processing method according to claim 1, wherein Step (2) comprises: using a calcined carbon black-graphite-PTFE air breathing cathode as a cathode and a titanium / iridium dioxide composite metal plate as an anode, introducing a 1-2 M NaOH electrolyte into the anode chamber, introducing a 50 mM-1 M Na2SO4 electrolyte into the cathode chamber, controlling the current to be 4.8-14.4 A, introducing an oxygen flow rate of 50-200 mL / min, and reacting for 6-15 hours to generate a 3-6% H2O2 solution.

5. The processing method according to claim 1, characterized in that In step (3), the volume of the H2O2 solution is 5% to 20% of the volume of the drilling fluid waste mud, and the stirring reaction time is 0.5 to 1.5 h; the mass of the calcium oxide powder is 2% to 5% of the weight of the drilling fluid waste mud.

6. The processing method according to claim 1, characterized in that The microbial bacterial liquid is an aqueous solution of Acinetobacter venetianus RAG-1, and the OD600 is 1.8-2.

8.

7. The processing method according to claim 1, characterized in that The microbial liquid is 10-30% of the volume increment of the mud cake.

8. The processing method according to claim 1, characterized in that In step (4), the reaction time is 4 to 8 days.

9. The processing method according to claim 1, wherein The COD of the leachate of the drilling waste that meets the emission standards is ≤150 mg / L.

10. A drilling waste cascade degradation treatment system based on electrochemical in-situ synthesis of H2O2, characterized in that: include: Drilling fluid waste mud collection tank (1); A coagulation tank (2) connected to the drilling fluid waste mud collection tank (1) for pretreatment with an iron-based coagulant; A H2O2 electrochemical synthesis device (3), the output end of which is connected to the coagulation tank (2); Plate and frame filter press (4), for solid-liquid separation; A microbial agent supply unit (5) sprays the bacterial solution onto the mud cake after filter pressing; The biochemical treatment unit (6) is used for microbial oxidation reaction.

11. The processing system according to claim 10, characterized in that The H2O2 electrochemical synthesis device (3) comprises: a cathode chamber comprising a cathode formed by a stacked arrangement of air-breathing cathode units; an anode chamber comprising an anode consisting of a titanium / iridium dioxide anode plate; An ion exchange membrane is used to separate the anode chamber and the cathode chamber.

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