Drilling waste cascade degradation treatment system and method based on in-situ synthesis of h2o2 by electrochemistry

Abstract

The present application belongs to the technical field of waste treatment, and relates to a drilling waste cascade degradation treatment system and method based on in-situ synthesis of H2O2 by electrochemistry. The drilling waste cascade degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry comprises the following steps: adding an iron-based coagulant into drilling fluid waste mud to form a flocculation system by stirring; producing H2O2 in-situ by using an electrochemical synthesis reactor to obtain a H2O2 solution; feeding the H2O2 solution into the flocculation system in batches, stirring and reacting, adding calcium oxide, and then performing solid-liquid separation after the reaction stops to obtain a mud cake; adding microbial liquid on the mud cake, and obtaining drilling waste meeting discharge standards through reaction. The present application uses electrochemical technology to in-situ synthesize high-concentration H2O2, adopts a two-stage physicochemical process, realizes preliminary degradation of polysulfonated drilling waste through multi-functional gradient utilization of the iron-based coagulant, and finally combines with microbial degradation to deeply degrade the waste.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of waste treatment, and relates to a drilling waste cascade degradation treatment system and method based on in-situ synthesis of H2O2 by electrochemistry, in particular to a collaborative treatment technology of self-supplying oxidant through cathode oxygen reduction reaction, combined with coagulation pretreatment-H2O2 oxidation-biological deep degradation. BACKGROUND

[0002] With the enhancement of environmental protection awareness of the petroleum industry, the discharge of drilling waste and the resulting environmental pollution problems are increasingly concerned by people. The pollutants in drilling waste mainly come from water-soluble additives of drilling fluid, and the pollutants have the characteristics of complex composition, high concentration, high colority and high COD value. In the drilling process, different drilling fluid systems need to be used with the change of depth. The introduction of different drilling fluid additives causes great changes in the composition of pollutants in drilling wastewater generated in the drilling process. The poly-sulfonated drilling fluid is often used in gas field deep well drilling (above 5000 m), which contains alkali, polymer, lubricant, sulfonated lignite (SMC), sulfonated phenolic resin (SMP), sulfonated asphalt (SAS), inhibitor, sodium silicate, humic acid and plugging agent, etc. According to the investigation, at present, the poly-sulfonated drilling fluid system is mainly used for deep well operation, and the high-temperature resistant sulfonated material is more commonly used, which has the main characteristics of high water-soluble COD value and high colority. At present, the COD value of the poly-sulfonated drilling fluid at the operation site is usually >20000 mg / L, and the COD value of the filter cake after flocculation pressure filtration is usually greater than 200 mg / L, which cannot meet the government discharge standard.

[0003] The common treatment technologies at home and abroad include solid-liquid separation technology, solidification technology, air flotation treatment, advanced oxidation technology (Fenton method, subcritical oxidation), biological composting, etc. Among them, the solid-liquid separation technology is to add a breaker, a flocculant, etc. (among them, the iron-based coagulant is a typical coagulant, which can not only play a coagulation role, but also can be used as a catalyst for advanced oxidation technology) in the waste mud to make it react chemically, thereby changing the properties of the slurry, destroying the stable colloidal system, making the small particles and suspended solids in it form larger flocs, and then separating the solid and liquid phases by mechanical centrifugation, pressure filtration, etc. However, the single use of this technology generally has a certain selectivity for organic matter, and it is difficult to make the pollutant discharge meet the standard, so it is often coupled with other technologies. The solidification treatment is to add a proper proportion of chemical additives and solidifying agent to the drilling fluid and mix them thoroughly, so that the drilling fluid loses stability and dehydrates. The solidifying agent reacts violently with the water in the drilling fluid, cross-links and flocculates with organic matter and solid particles, forming a hydrated flocculation system of solid-solidifying agent-water. Through self-cementation and encapsulation, it gradually changes into an irreversible normal solid. The solidified material has water resistance, encapsulation and adsorption, so as to limit the flow of drilling waste liquid and inhibit the migration and diffusion of its components. Although the solidification method has fast treatment speed and good treatment effect, it does not have strong adaptability. The solidification formula needs to be adjusted through experiments on site, which is inconvenient to operate, delays time and affects the construction process. There is also a long-term leakage risk. The air flotation technology is a commonly used drilling waste liquid treatment technology. By aeration, highly dispersed micro-bubbles are formed in the water, which adhere to the hydrophobic solid or liquid particles in the waste water to form a water-gas-particle three-phase mixed system. After the particles adhere to the bubbles, the apparent density of the flocs is less than that of water, and they float to the water surface to form a scum layer which is scraped off. The COD of the final mud cake is reduced by the migration and / or degradation of the organic matter in the whole base fluid. For drilling waste liquid with high water content and high emulsification degree, the air flotation technology can make up for the shortcomings of the chemical solid-liquid separation water treatment technology. However, this technology still has the disadvantages of high energy consumption, large occupation area, unsuitability for high solid content fluid, easy clogging of the aeration port, etc. The principle of the advanced oxidation technology (Fenton method) is that Fe²⁺ catalyzes the decomposition of H2O2 to generate ·OH to oxidize and decompose refractory organic matter. This technology uses hazardous chemicals, which has a high safety risk in transportation and storage. The advanced oxidation technology (subcritical oxidation) can degrade the organic matter in the waste water into harmless substances such as CO2, H2O and N2 under the subcritical state of water, and the COD is greatly reduced. The subcritical state condition has high requirements for equipment, etc., and the process flow is complex, so it is difficult to control the subcritical state. The biological composting method uses microorganisms to completely mineralize organic matter, which has a long cycle, is greatly affected by the environment, and the effect is uncontrollable, so it occupies a large area.

[0004] Advanced oxidation technology based on electrochemical catalytic oxygen reduction reaction has attracted much attention due to its high efficiency and environmental protection. This technology uses oxygen (even ordinary air) to synthesize H2O2 in situ at room temperature and normal pressure through electrochemical reaction, and the reaction process is simple and does not require complex conditions. H2O2, as a strong oxidant, can generate hydroxyl radicals (·OH) through various ways (such as photolysis, catalytic decomposition, etc.). ·OH is a highly active oxygen species with a very high oxidation potential, which can degrade a variety of organic matter without selectivity, and plays a key role in advanced oxidation processes. In practical applications, the Fenton method with ferrous ions (Fe 2+ ) as catalyst is a typical advanced oxidation technology. Fenton method generates ·OH by Fe 2+ -catalyzed decomposition of H2O2, which shows excellent degradation effect on pollutants in drilling fluid wastewater. This technology not only has mild reaction conditions, but also can effectively treat high-concentration and high-toxicity organic wastewater. However, this method still has certain limitations in practical application. H2O2, as a strong oxidant, has a high safety risk in transportation and storage, and strict protective measures are required. In addition, the applicability of this technology still needs to be further expanded. Especially for some high-COD waste, it is difficult to achieve complete degradation of pollutants by relying solely on Fenton oxidation method, which may not meet the strict emission standards. Physicochemical coupling with biological treatment technology is a relatively applicable technology for onshore drilling platforms. By using one or more physicochemical processes, the refractory organic pollutants in drilling waste are pre-oxidized to break down into small molecular organic pollutants that can be biodegraded, and then combined with biological treatment technology, i.e. using the metabolic action of microorganisms to remove residual organic matter in drilling waste, which can improve the treatment efficiency and significantly reduce the cost of chemical reagent consumption.

[0005] In the prior art, as described in the patent A kind of water-based drilling fluid solid-liquid waste harmless deep treatment method (application number: CN202111579505.4) First, after oil-water separation, mud is obtained, mud is mixed with gel breaker and flocculant, second solid-liquid separation is carried out, second liquid phase and second solid phase are obtained;The second liquid phase is treated by water, and the standard discharge wastewater and the third solid phase are obtained.The patent uses a combined process in the water treatment process of the second liquid phase, including sequentially carrying out air floatation treatment, coagulation treatment and electrochemical oxidation treatment.The treatment process and stage of the patent are too complicated, and accordingly, the patent innovatively proposes to add a coagulant to the drilling waste mud and then directly perform electrochemical oxidation, which is obviously different from the comparative patent, can simplify the treatment process, realize gradient utilization of the iron-based coagulant, preliminarily oxidize the drilling waste, and improve the biodegradability of the mud cake.Meanwhile, the patent A biological composting treatment method for oil-based drilling waste (application number: CN2014100391397) can screen out strains that can efficiently degrade petroleum hydrocarbons from oil-based drilling waste, and prepare a solid compound microbial agent through orthogonal experiment;The solid compound microbial agent is added to the oil-based drilling waste, and rice chaff is used as a support to mix uniformly, to obtain a fertilizer pile of the oil-based drilling waste;The carbon-nitrogen ratio and moisture content of the fertilizer pile are adjusted, and the pile is turned over and sampled for analysis to complete on-site composting.After 1 month of treatment, the total petroleum hydrocarbon degradation rate in the oil-based drilling waste can reach more than 80%.The method described in the patent has a long treatment time, and it is difficult to realize the reaction of a large amount of pollutants, and the organic matter in the pollutants is directly degraded by microorganisms.However, the functional microbial agent screened out in the present patent can effectively degrade the organic matter within 5 days, improve the degradation efficiency, and realize gradient degradation of the organic matter, and deep degradation of the simple organic matter after physical and chemical treatment. SUMMARY

[0006] The present application aims to overcome the defects of the prior art and provides a drilling waste gradient degradation treatment system and method based on in-situ synthesis of H2O2 by electrochemistry.

[0007] Specifically, the present application provides a drilling waste gradient degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, which comprises:

[0008] (1) adding an iron-based coagulant to the drilling fluid waste mud, and stirring to form a flocculation system;

[0009] (2) using an electrochemical synthesis reactor to produce H2O2 in-situ to obtain an H2O2 solution;

[0010] (3) adding the H2O2 solution to the flocculation system of step (1) in batches, stirring and reacting, adding calcium oxide, and performing solid-liquid separation after the reaction stops to obtain a mud cake;

[0011] (4) adding microbial bacteria liquid to the mud cake, and reacting to obtain drilling waste reaching the discharge standard.

[0012] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, the iron-based coagulant is one or more of ferrous sulfate, ferric sulfate, polymeric ferric sulfate, ferric chloride and polymeric ferric chloride.

[0013] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, the volume ratio of the iron-based coagulant to the drilling fluid waste mud is (4g-10g):100mL.

[0014] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, step (2) comprises: taking calcined carbon black-graphite-PTFE air-breathing cathode as a cathode, titanium / iridium dioxide composite metal plate as an anode, introducing 1-2 M NaOH electrolyte into the anode chamber, introducing 50 mM-1 M Na2SO4 electrolyte into the cathode chamber, controlling the current to be 4.8-14.4 A, introducing oxygen flow at a speed of 50-200 mL / min, and reacting for 6-15 hours to generate 3-6% H2O2 solution.

[0015] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, in step (3), the volume of the H2O2 solution is 5-20% of the volume of the drilling fluid waste mud, and the stirring reaction time is 0.5-1.5 h; the mass of the calcium oxide powder is 2%-5% of the weight of the drilling fluid waste mud.

[0016] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, the microbial bacteria liquid is an aqueous solution of Acinetobacter venetianus RAG-1, and the OD600 is 1.8-2.8.

[0017] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, the microbial bacteria liquid is 10-30% of the volume increment of the mud cake.

[0018] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, in step (4), the reaction time is 4-8 days.

[0019] The drilling waste step-by-step degradation treatment method based on in-situ synthesis of H2O2 by electrochemistry, the leaching solution of the drilling waste reaching the discharge standard has a COD of less than or equal to 150 mg / L.

[0020] The drilling waste step-by-step degradation treatment system based on in-situ synthesis of H2O2 by electrochemistry comprises:

[0021] A drilling fluid waste mud collecting tank 1 is provided.

[0022] A coagulation tank 2 is connected to the drilling fluid waste mud collecting tank 1 and is used for pretreatment of an iron-based coagulant.

[0023] An H2O2 electrochemical synthesis device 3 is connected to the coagulation tank 2.

[0024] A plate-and-frame filter press 4 is used for solid-liquid separation.

[0025] A microbial agent supply unit 5 sprays microbial liquid on the mud cake after filtration.

[0026] A biochemical treatment unit 6 is used for microbial oxidation reaction.

[0027] The drilling waste step-by-step degradation treatment system based on electrochemical in-situ synthesis of H2O2 has the H2O2 electrochemical synthesis device 3 comprising:

[0028] A cathode chamber comprising a cathode composed of a stack of air-breathing cathode units.

[0029] An anode chamber comprising an anode composed of a block titanium / iridium dioxide anode plate.

[0030] An ion exchange membrane for separating the anode chamber and the cathode chamber.

[0031] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0032] (1) The present application uses electrochemical technology to in-situ synthesize high-concentration H2O2, adopts a two-stage physicochemical process, i.e., coagulation and H2O2 oxidation process, and realizes preliminary degradation of polysulfonated drilling waste through gradient utilization of the iron-based coagulant, and finally realizes deep degradation of the waste by combining with microbial degradation. The complex organic matter in the polysulfonated drilling waste is completely mineralized after a step-by-step degradation, and the COD of the filter cake leaching liquid is less than 150 mg / L (DB65 / T 3997-2017), reaching the discharge standard.

[0033] (2) The present application avoids the safety problems of transportation and storage of hazardous chemicals by in-situ synthesis of H2O2 through electrochemistry. The gradient utilization of the iron-based coagulant can reduce the dosage of the reagent and improve the degradation efficiency. After the gradient degradation through the coupling technology, the waste is discharged in a short time and meets the standard, which is better suitable for industrial field operation, and finally realizes safe and green treatment of polysulfonated drilling waste.

[0034] (3) The present application realizes the synergistic effect of gradient utilization of iron-based coagulant and in-situ synthesis of oxidant through the coupling mechanism of physicochemical-biochemical, and realizes the synergistic effect of gradient utilization of iron-based coagulant and in-situ synthesis of oxidant. Combined with the electrochemical H2O2 production and use technology, the loss of oxidant storage and transportation is avoided, the macromolecular pollutants are efficiently degraded by ·OH, and the degradation closed loop of “physicochemical crushing-biological mineralization” is formed. In practical application, the COD can be reduced to 108 mg / L at the lowest, the treatment period is as short as 5 days, and the method has effective effect on various polysulfonated drilling fluid waste. In the implementation process of the present application, no strong acid / strong base is added, the final product is stable and reaches the national secondary discharge standard, and a green and efficient solution for polysulfonated drilling waste treatment is provided. BRIEF DESCRIPTION OF DRAWINGS

[0035] Various other advantages and benefits will become apparent to those of ordinary skill in the art upon reading the following detailed description of the preferred embodiments with reference made to the accompanying drawings. The drawings are for purposes of illustration only and are not considered a limitation of the present application.

[0036] Figure 1 FIG. 1 is a schematic diagram of a drilling waste step degradation treatment system based on electrochemical in-situ synthesis of H2O2 according to the present application.

[0037] Figure 2 FIG. 5 is the COD concentration in the drilling waste step degradation treatment process in Example 1.

[0038] Figure 3 FIG. 6 is the COD concentration in the drilling waste step degradation treatment process in Example 2.

[0039] Figure 4 FIG. 7 is the COD concentration in the drilling waste step degradation treatment process in Example 3.

[0040] Figure 5 FIG. 8 is the COD concentration in the drilling waste step degradation treatment process in Example 4.

[0041] Figure 6 FIG. 9 is the COD concentration in the drilling waste step degradation treatment process in Example 5.

[0042] Figure 7 FIG. 10 is the COD concentration in the drilling waste step degradation treatment process in Example 6.

[0043] Figure 8 FIG. 11 is the COD concentration in the drilling waste step degradation treatment process in Example 7.

[0044] Figure 9 FIG. 12 is the COD concentration in the drilling waste step degradation treatment process in Example 8.

[0045] Figure 10 FIG. 13 is the COD concentration in the drilling waste step degradation treatment process in Example 9. DETAILED DESCRIPTION

[0046] For the purpose of fully understanding the present application, its technical solutions and advantages, a detailed description will be given to the present application with reference to the following embodiments. The process of the present application adopts conventional methods or devices in the field except the following contents. The following terms have the meanings commonly understood by those skilled in the art unless otherwise specified.

[0047] When a numerical range is disclosed herein, the range is to be construed as continuous, and includes the minimum and maximum values of the range, as well as every value between the minimum and maximum values. Further, when the range is of integers, 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 to be understood as including any and all sub-ranges subsumed therein.

[0048] The concept of the present application is to overcome the technical defects of the existing treatment methods, such as low degradation efficiency, high cost of reagents, risk of secondary pollution, and restriction on the use of hazardous chemicals, by in-situ electrochemical synthesis of high-concentration H2O2, combined with coagulation-H2O2 oxidation and coupling microbial oxidation, to realize complete degradation of polysulfonated drilling waste, achieve deep degradation of polysulfonated drilling fluid waste, and make the filter cake COD ≤ 150 mg / L (DB65 / T 3997-2017) to meet the emission standard.

[0049] Specifically, the present application provides a drilling waste cascade degradation treatment method based on in-situ electrochemical synthesis of H2O2, which comprises:

[0050] (1) Iron-based coagulation pretreatment

[0051] An iron-based coagulant is added to the drilling fluid waste mud, and then stirring treatment is performed until a large amount of flocculation appears, and the stirring is stopped.

[0052] In some preferred embodiments, the iron-based coagulant is one or more of ferrous sulfate, ferric sulfate, polymeric ferric sulfate, ferric chloride, and polymeric ferric chloride, and is further preferably ferrous sulfate.

[0053] In some preferred embodiments, the weight / volume ratio of the iron-based coagulant to the drilling fluid waste mud is (4 g-10 g): 100 mL.

[0054] (2) In-situ electrochemical synthesis of H2O2

[0055] An electrochemical synthesis reactor is used to produce H2O2 in-situ to obtain a H2O2 solution.

[0056] In some preferred embodiments, the electrochemical in-situ synthesis of H2O2 uses a calcined carbon black-graphite-PTFE air-breathing cathode as the cathode, a titanium / iridium dioxide composite metal plate as the anode, 1-2 M NaOH electrolyte is introduced into the anode chamber, 50 mM-1 M Na2SO4 electrolyte is introduced into the cathode chamber, the current is controlled at 4.8-14.4 A, the oxygen flow rate is 50-200 mL / min, and the reaction is carried out for 6-15 hours to generate a 3-6% H2O2 solution.

[0057] (3) H2O2 oxidation treatment

[0058] The H2O2 solution is introduced into the flocculation system of step (1) in batches, stirring is carried out, calcium oxide is added, and after the reaction is stopped, solid-liquid separation is carried out to obtain a mud cake.

[0059] In some preferred embodiments, the volume of the H2O2 solution is 5-20% of the volume of the drilling fluid waste mud, and the stirring reaction time is 0.5-1.5 h.

[0060] The present application removes most of the silicates through flocculation+oxidation process, and oxidizes long-chain hydrocarbons into short-chain hydrocarbons, thereby improving the biodegradability of organic matter in the mud cake.

[0061] By adding CaO, the pH of the mud can be increased, and Fe 2+ 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%-5% of the weight of the drilling fluid waste mud.

[0062] (4) Microbial oxidation treatment

[0063] Microbial bacteria solution is added to the mud cake by spraying or other methods, and after 4-8 days of reaction, drilling waste with a leaching liquid COD≤150 mg / L is obtained.

[0064] In some preferred embodiments, the microbial bacteria solution is an aqueous solution of Acinetobacter venetianus RAG-1, and the OD600 is 1.8-2.8, and is further preferably 2.5.

[0065] In some preferred embodiments, the microbial bacteria solution is 10-30% of the volume increment of the mud cake.

[0066] The "volume increment" refers to the ratio of the added volume of the microbial bacteria solution to the volume of the mud cake itself. For example, if the microbial bacteria solution is 10-30% of the volume increment of the mud cake, it means that 1 m 3 The mud cake is added with 0.1 m 3 ~ 0.3 m 3of bacterial liquid.

[0067] 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:

[0068] Drilling fluid waste mud collection tank 1;

[0069] Coagulation tank 2, connected to the drilling fluid waste mud collection tank 1, used for iron-based coagulant pretreatment;

[0070] H2O2 electrochemical synthesis device 3, the output end of which is connected to the coagulation tank 2;

[0071] Plate and frame filter press 4, for solid-liquid separation;

[0072] The microbial agent supply unit 5 sprays the bacterial solution onto the mud cake after filtration;

[0073] The biochemical treatment unit 6 is used for microbial oxidation reaction.

[0074] In some preferred embodiments, the main body of the H2O2 electrochemical synthesis device 3 is made of organic glass and includes:

[0075] a cathode chamber comprising a cathode formed by a stacked arrangement of air-breathing cathode units;

[0076] an anode chamber comprising an anode consisting of a titanium / iridium dioxide anode plate;

[0077] An ion exchange membrane is used to separate the anode chamber and the cathode chamber.

[0078] 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 .

[0079] 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.

[0080] In some preferred embodiments, the size of the ion exchange membrane is 5 cm*5 cm, and the model is CAM-1680.

[0081] The application first proposes a coagulation, electrochemical oxidation combined with biodegradation coupling technology based on in-situ synthesis of high-concentration H2O2. The technology innovatively uses in-situ synthesis of high-concentration H2O2 for oxidative degradation of polysulfonated drilling waste, realizing multifunctional gradient utilization of iron-based coagulant (i.e., playing a coagulant function in the coagulation stage and a catalyst function in the oxidation stage). At the same time, the application converts complex organic matter into simple organic matter that can be utilized by microorganisms through the physicochemical treatment stage, and finally mineralizes the organic matter in the drilling waste by the metabolic action of microorganisms, realizing the cascade degradation of the organic matter in the drilling waste.

[0082] Examples

[0083] The application will be further described by way of examples, but the application is not limited to the scope of the examples. The experimental methods in the following examples without specific conditions are carried out according to the conventional methods and conditions. The raw materials used in the following examples are all commercially available.

[0084] Example 1

[0085] This example processes the polysulfonated drilling fluid waste generated in the 8 1 / 2" upper well section, and the COD of the leaching solution of the untreated mud cake is about 1052 mg / L. Figure 2

[0086] (1) 3 g of ferrous sulfate is added to the generated 50 mL (62.5 g) of waste to cause a coagulation reaction;

[0087] (2) 1 L of 2 M NaOH electrolyte is added to the anode chamber of the electrochemical synthesis reactor, and 1.5 L of 1 M Na2SO4 electrolyte is added to the cathode chamber. Four Ti / IrO2 anode plates (size: 4 cm * 10 cm * 1 mm, mass ratio of iridium dioxide coating to titanium plate area: 10 g / m 2 ) are connected to the positive electrode of the direct current power supply, and the cathode plates (size: 14 cm * 2 cm * 6 cm) in the six groups of air-breathing cathode units are connected to the negative electrodes of the direct current power supply, respectively, and the current of the direct current power supply is controlled to be 9.6 A. Oxygen is introduced into the closed gas chambers of the six groups of air-breathing cathode units from the oxygen cylinder through the blast needle, and the gas flow rate is 150 mL / min. The hydrogen peroxide concentration is measured by the potassium titanyl oxalate spectrophotometric method at fixed points every 1 h, and the reactor is operated for 11 hours to synthesize 5% H2O2 solution.

[0088] ​(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.

[0089] (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.

[0090] Example 2

[0091] This example deals with the waste of polysulfone drilling fluid generated in the upper section of the 8 1 / 2" well. Figure 3 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 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.

[0092] Example 3

[0093] This example deals with the waste of polysulfone drilling fluid generated in the upper section of the 8 1 / 2" well. Figure 4The 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.

[0094] Example 4

[0095] This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 5 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 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.

[0096] Example 5

[0097] This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 6The 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.

[0098] Example 6

[0099] This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 7 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 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.

[0100] Example 7

[0101] This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 8The 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.

[0102] Example 8

[0103] This example deals with the waste of polysulfone drilling fluid generated in the 8 1 / 2" downhole section. Figure 9 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. 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.

[0104] Example 9

[0105] This example deals with the waste of polysulfone drilling fluid produced in the 8 1 / 2" downhole section. Figure 10The COD of the leaching solution of the untreated sludge cake is about 1326 mg / L. First, 3 g of ferrous sulfate is added to the generated 50 mL (62.5 g) waste to cause coagulation, and then 5 mL of H2O2 solution prepared according to the method of Example 1 is added to the slurry after coagulant treatment. The H2O2 solution is added twice, and after a period of reaction, 2.5 g of calcium oxide powder is added. The slurry is separated by pressure filtration, and the COD of the leaching solution of the sludge cake after two physical and chemical treatments is reduced to 249 mg / L. It is detected that the moisture content of the sludge cake is about 25%, the density is about 1.25 kg / m 3 , and the volume of 5 g of sludge cake is about 4 cm 3 . Microbial solution with OD600 of about 2.5 is added to the sludge cake Acinetobacter venetianus RAG-1, wherein the ratio of sludge cake mass to microbial solution volume is 5 g: 1 mL (the volume of the microbial solution is increased by 25%), and it is placed in a 15°C incubator. After 5 days of reaction, the moisture content of the sludge cake is less than 25%, the COD of the leaching solution is further reduced, and the COD of the leaching solution is reduced to 121 mg / L, finally reaching the discharge standard.

[0106] The present application has been disclosed in the foregoing by preferred embodiments, but those skilled in the art should understand that these embodiments are only used to depict the present application, and should not be understood as limiting the scope of the present application. It should be noted that any changes and substitutions equivalent to these embodiments should be considered as covered by the scope of the claims of the present application. Therefore, the scope of protection of the present application should be limited by 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; 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; in step (3), the volume of the H2O2 solution is 5-20% of the volume of the drilling fluid waste mud, and the stirring reaction time is 0.5-1.5 h; the mass of the calcium oxide powder is 2%-5% of the weight of the drilling fluid waste mud; Wherein, the microbial bacterial solution is an aqueous solution of Acinetobacter venetianus RAG-1, and the OD600 is 1.8-2.8; The method for treating drilling waste by cascade degradation based on electrochemical in-situ synthesis of H2O2 is carried out in a drilling waste cascade degradation treatment system based on electrochemical in-situ synthesis of H2O2, the treatment system comprising: 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.

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, characterized in that The microbial liquid is 10-30% of the volume increment of the mud cake.

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

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

7. The processing method according to claim 1, 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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