Harmless and recycling treatment system and method for waste drilling fluid

Abstract

The invention discloses a harmless and recycling treatment system and method for waste drilling fluid, and relates to the technical field of waste drilling fluid treatment.The harmless and recycling treatment method comprises the following steps that S1, calcification-free demulsification and dehydration are conducted, specifically, a demulsification agent combination is added into waste drilling fluid hydraulic filtrate, the demulsification agent combination comprises 1.3-1.7 g / L of kieselguhr, 0.08-0.12 mol / L of NaOH, 0.25-0.35 g / L of FeCl3 and 8-12 mg / L of PAM, and mud-water separation is conducted; by adopting a primary treatment process of destabilizing and crystallizing CaSO4 and cooperatively softening Na2CO3, the removal rate of calcium ions is increased to 97.3%, the removal rate of magnesium ions reaches 72.5%, the calcium ions are further reduced to 62mg / L after secondary treatment of the NF membrane, and the water inlet hardness requirement and the final recycling standard of the NF membrane are comprehensively met.

Description

Technical Field

[0001] The present invention relates to the technical field of waste drilling fluid treatment, and in particular to a waste drilling fluid harmless treatment and reuse treatment system and method. Background Art

[0002] In the field of oilfield exploitation, if the waste drilling fluid generated by drilling operations is directly discharged without proper treatment, it will cause serious pollution to water bodies, soil and groundwater systems. The drilling hydraulic filtrate contains a large amount of suspended matter, high-valent anions and cations, difficult-to-biodegrade organic matter and heavy metals and other impurities. Among the existing technologies at home and abroad, the mainstream treatment method is solid-liquid separation, such as chemically enhanced solid-liquid separation technology, coagulation and sedimentation, etc., but the separated water is not deeply treated and still needs to be transported to a centralized treatment station, which is costly and inefficient. Some domestic on-site treatment methods are rough, and the scrapped mud is directly transported to the brick factory without treatment or with simple treatment, or flocculation sedimentation mud-water separation filter technology is used, but the filtrate is not deeply treated, resulting in waste of resources and environmental pollution. The lack of unified filtrate reuse standards has restricted the development of resource utilization.

[0003] The existing harmless treatment of waste drilling fluid has the following defects:

[0004] 1. Patent document CN104944480A discloses a harmless treatment agent for waste drilling fluid. "The present invention relates to a harmless treatment agent for waste drilling fluid. It mainly solves the problem that the existing "solidification" treatment method for waste drilling fluid cannot fundamentally remove its harmful substances and is prone to secondary pollution. The components and proportions of the harmless treatment agent for waste drilling fluid are as follows in percentage by weight: pH value regulator 1.0% to 1.5%, heavy metal removal agent 0.7-1.0%, oxidation removal agent 2.0-2.5%, flocculant 1.5-2.0%, coagulant aid 0.05% to 0.1%, decolorant 2.0% to 2.5%. The liquid phase of the product after treatment with the harmless treatment agent for waste drilling fluid can be used as water for oilfield reinjection, and the solid phase can be used for paving well sites and maintaining well drainage roads, thereby realizing the resource recycling of waste." However, the devices described in the above documents have the technical problem of low calcium ion removal rate due to the use of chemical precipitation method in most of the devices;

[0005] 2. Patent document CN108316873B discloses a water-based drilling waste harmless treatment device, method, and use. "The present invention provides a water-based drilling waste harmless treatment device, method, and use. The water-based drilling waste harmless treatment device includes a non-ground collection unit, a liquid phase regeneration treatment unit, and a solid phase harmless treatment unit; the non-ground collection unit is respectively connected to the liquid phase regeneration treatment unit and the solid phase harmless treatment unit; the liquid phase regeneration treatment unit is connected to the solid phase harmless treatment unit. The water-based drilling waste harmless treatment device and method of the present invention saves land and treatment costs, and saves costs such as harmless treatment of drilling waste, landfill excavation and anti-seepage. The pH, COD, chroma, and petroleum content of the base soil and unfired building blocks prepared after harmless treatment of drilling waste meet environmental protection requirements, and the unfired blocks and base soil meet relevant building material standards, thus achieving the recycling and resource utilization of drilling waste. However, the device described in the above document has a technical problem that the filtrate is difficult to reuse, resulting in a waste of water resources.

[0006] 3. Patent document CN108640218A discloses a method and application for solid-liquid separation of waste drilling fluid. “The present invention relates to a method and application for solid-liquid separation of waste drilling fluid. The technical solution comprises three steps: ultrasonic treatment, waste drilling fluid centrifugation, and solid-liquid phase separation. The ultrasonic treatment time is 15 min to 60 min, and the ultrasonic treatment frequency is 18 kHz to 25 kHz. The centrifugal time of the centrifuge is 10 min to 60 min, and the centrifugal speed of the centrifuge is 2000 r / min to 4000 r / min. r / min; the method for solid-liquid phase separation of waste drilling fluid is to separate the waste drilling fluid after centrifugation. The beneficial effects of the present invention are: compared with conventional drilling fluid solid-liquid separation methods such as plate and frame filter pressing and high-speed centrifugation, the waste drilling fluid solid-liquid separation treatment method provided by the present invention adopts ultrasonic treatment, waste drilling fluid centrifugation, and solid-liquid phase separation. The treatment process is simple, highly operable, and has low treatment costs. It is particularly suitable for the harmless treatment and resource utilization of waste drilling fluid in the process of oil and natural gas exploration and development. However, the device in the above document has a technical problem of low heavy metal removal rate. Summary of the Invention

[0007] The purpose of the present invention is to provide a system and method for harmless treatment and reuse of waste drilling fluid to solve the technical problems raised in the above background technology.

[0008] To achieve the above-mentioned object, the present invention provides the following technical solution: a method for harmless treatment and reuse of waste drilling fluid, comprising the following steps;

[0009] S1. Non-calcified demulsification and dehydration: Add a demulsifier combination containing 1.3-1.7 g / L diatomaceous earth, 0.08-0.12 mol / L NaOH, 0.25-0.35 g / L FeCl3, and 8-12 mg / L PAM to the waste drilling hydraulic filtrate to separate the mud and water;

[0010] S2, primary nucleus crystal granulation to remove calcium and magnesium: the filtrate obtained in step S1 is fed into the primary nucleus crystal granulation device, 80-120 g / L of CaSO4 is added and the pH is adjusted to 8.5-9.5. After reacting for 2-24 hours, 0.8-1.2 mol / L of Na2CO3 and 0.15-0.25 mol / L of NaOH are added and the reaction time is 1-3 hours;

[0011] S3, secondary nucleation granulation to remove heavy metals: the filtrate treated in step S2 is fed into a secondary nucleation granulation device, 1.2-1.8 mmol / L of Na2S is added and the pH is adjusted to 9.0-10.0, and the reaction time is 20-40 minutes;

[0012] S4, deep filtration: the filtrate treated in step S3 is sequentially passed through a multi-media filtration, activated carbon filtration and nanofiltration (NF) membrane assembly, wherein the NF membrane operating pressure is 1.2-1.8 MPa, so that the filtrate water quality meets the reuse standard;

[0013] S5. Reuse: The produced water obtained in step S4 is reused for drilling mud preparation, and the concentrated liquid is discharged for disposal.

[0014] Preferably, the demulsifier composition in step S1 is 1.5 g / L diatomaceous earth, 0.10 mol / L NaOH, 0.3 g / L FeCl3 and 10 mg / L PAM.

[0015] Preferably, in step S2, the dosage of CaSO4 is 100 g / L, the pH is 9, and after reacting for 24 hours, 1.0 mol / L of Na2CO3 and 0.2 mol / L of NaOH are added and reacted for 2 hours.

[0016] Preferably, in step S3, the dosage of Na2S is 1.5 mmol / L, the pH is 9.5, and the reaction is carried out for 30 minutes.

[0017] Preferably, the retention rate of divalent ions of the NF membrane in step S4 satisfies: Ca 2+ Retention rate ≥65%, SO4 2- Retention rate ≥90%.

[0018] Preferably, the water quality of the recycled water in step S5 satisfies: Ca 2+ ≤180mg / L, Mg 2+≤108mg / L, Zn 2+ ≤0.130mg / L, Mn 2+ ≤0.3mg / L, SO4 2- ≤250mg / L, suspended solids ≤10mg / L, chemical oxygen demand (COD) ≤100mg / L, petroleum ≤0.5mg / L, pH 6-9, total nitrogen ≤200mg / L, Fe 3+ ≤0.5mg / L, NO3 - ≤10mg / L.

[0019] Preferably, the following modular units are integrated into the container:

[0020] Non-calcified demulsification unit, equipped with demulsification agent dosing device;

[0021] The first-stage nucleus crystal granulation unit and the second-stage nucleus crystal granulation unit connected in series are respectively equipped with:

[0022] Primary nucleus crystal granulation unit: CaSO4, Na2CO3, NaOH dosing system and pH adjustment device;

[0023] Secondary nuclear crystal granulation unit: Na2S dosing system and pH adjustment device;

[0024] The depth filtration unit includes a multi-media filter, an activated carbon filter and a NF membrane assembly in sequence;

[0025] A recycled water tank and a concentrated liquid collection tank are provided, wherein the input port of the recycled water tank is connected to the water production port of the NF membrane assembly, and the input port of the concentrated liquid collection tank is connected to the concentrated water port of the NF membrane assembly.

[0026] Preferably, the primary nucleus crystal granulation unit is equipped with a pH online monitor and an automatic control system linked to the CaSO4, Na2CO3, and NaOH dosing pumps;

[0027] The secondary nucleus crystal granulation unit is equipped with an ORP sensor and a Na2S dosing automatic control system.

[0028] Preferably, the NF membrane module is provided with an operating pressure control system and a membrane fouling monitor, and the operating pressure control system and the membrane fouling monitor are interlocked.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. This invention uses a primary treatment process of CaSO4 destabilization crystallization and Na2CO3 synergistic softening to increase the calcium ion removal rate to 97.3% and the magnesium ion removal rate to 72.5%. After secondary treatment with the NF membrane, the calcium ion is further reduced to 62 mg / L, fully meeting the NF membrane inlet water hardness requirements and final reuse standards.

[0031] 2. The present invention introduces Na2S co-precipitation technology through the innovative secondary nucleation granulation process, breaking through the bottleneck of traditional heavy metal treatment: Zn 2+ The removal rate is 98.5%, Mn 2+ The removal rate was 91.9%, and the concentrations after treatment were as low as 0.05 mg / L and 0.12 mg / L respectively;

[0032] 3. This invention uses a three-stage combination of multi-media filtration, activated carbon adsorption, and NF membrane technology to achieve efficient interception of organic matter and suspended solids: COD is reduced from 85mg / L to 42mg / L, SS is reduced from 243mg / L to 5.2mg / L, and the turbidity removal rate reaches 56.3%. The final effluent water quality fully meets the requirements for slurry preparation water. Furthermore, through graded treatment and synergistic efficiency enhancement mechanisms, the feasibility of resource reuse of complex wastewater is significantly improved.

[0033] 4. The present invention can reuse the monovalent salts such as NaCl and KCl retained in the filtrate and use them directly for slurry preparation, which is beneficial to saving drug costs;

[0034] 5. The present invention integrates each modular unit into a container to adapt to the migration requirements of the drilling platform, thereby improving mobility and compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the processing method of the present invention;

[0036] Figure 2 Schematic diagram of the system flow of the present invention.

[0037] In the figure: 1. Calcification-free demulsification unit; 2. Primary nucleation granulation unit; 3. Secondary nucleation granulation unit; 4. Depth filtration unit; 5. Multi-media filter; 6. Activated carbon filter; 7. NF membrane assembly; 8. Recycled water tank; 9. Concentrate collection tank. DETAILED DESCRIPTION

[0038] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Example 1: Please refer to Figure 1 and Figure 2 , an embodiment provided by the present invention:

[0040] It includes the following modular units integrated in the container: a calcification-free demulsification unit 1, equipped with a demulsification agent dosing device, a first-level nucleus crystallization granulation unit 2 and a second-level nucleus crystallization granulation unit 3 connected in series, respectively equipped with, the first-level nucleus crystallization granulation unit 2: CaSO4, Na2CO3, NaOH dosing system and pH adjustment device, the second-level nucleus crystallization granulation unit 3: Na2S dosing system and pH adjustment device, a depth filtration unit 4, which sequentially includes a multi-media filter 5, an activated carbon filter 6 and a NF membrane assembly 7, a reuse water tank 8 and a concentrate collection tank 9, and the input port of the reuse water tank 8 is connected to the water outlet of the NF membrane assembly 7, and the input port of the concentrate collection tank 9 is connected to the concentrated water outlet of the NF membrane assembly 7, the first-level nucleus crystallization granulation unit 2 is equipped with a pH online monitor and an automatic control system linked to the CaSO4, Na2CO3, and NaOH dosing pumps, the second-level nucleus crystallization granulation unit 3 is equipped with an ORP sensor and a Na2S dosing automatic control system, the NF membrane assembly 7 is provided with an operating pressure control system and a membrane pollution monitor, and the operating pressure control system is interlocked with the membrane pollution monitor.

[0041] Experiment 1: Adding a demulsifier combination to the waste drilling hydraulic filtrate, the demulsifier combination is 1.5g / L diatomaceous earth, 0.10mol / L NaOH, 0.3g / L FeCl3 and 10mg / L PAM;

[0042] Furthermore, demulsifiers are added to destroy the emulsified state in the filtrate, promote the separation of oil, water and mud, and cause the suspended matter and colloidal particles to coagulate and precipitate.

[0043] Experiment 2: Primary core crystal granulation for decalcification and softening:

[0044] Dosage conditions: 100g / L CaSO4, 1.0mol / L Na2CO3 and 0.2mol / L NaOH;

[0045] Reaction parameters: pH = 9.0 ± 0.2, stirring speed 300 rpm, reaction time 2 hours;

[0046] Table 1 Effect of primary nucleus granulation treatment

[0047]

[0048] Furthermore, it can be seen from the table above that the application of the nuclear crystal granulation device, the destabilization crystallization of CaSO4 combined with the synergistic softening of Na2CO3 and NaOH can significantly reduce the concentration of calcium and magnesium. 2+ Removal rate>97%, Mg 2+ Removal rate 72.5%, residual concentration 22mg / L

[0049] Experiment 3: Secondary nucleation granulation for heavy metal removal: Dosing conditions: 1.5 mmol / L Na2S, pH adjusted to 9.5 ± 0.2, reaction parameters: stirring speed 200 rpm, reaction time 30 minutes:

[0050] Table 2 Secondary nucleus crystal granulation treatment effect

[0051]

[0052] Furthermore, according to the data in the table, it can be seen that the Na2S precipitation method has a significant effect on the removal of heavy metals, Zn 2+ 、Fe 3+ The removal rate is >98%, Mn 2+ Removal rate>91%.

[0053] Experiment 4: Verify whether the filtrate pre-treated by the core crystal granulation device can meet the "Standard for Reuse of Filtrate" after being treated by the depth filtration unit 4:

[0054] Pre-treatment water quality: Ca in the effluent from the nuclear crystal granulation device 2+ :195mg / L、Mg 2+ :22mg / L、Zn 2+ :0.28 mg / L、Fe 3+ :0.04mg / L、Mn 2+ : 0.35mg / L, pH: 9.4;

[0055] The composition of the depth filtration unit 4 includes:

[0056] Multi-media filter 5: quartz sand + anthracite, filtration accuracy is 10μm, flow rate is 2m³ / h.

[0057] Activated carbon filter 6: coconut shell activated carbon, particle size 1.5mm, adsorption time 30min.

[0058] NF membrane component 7: polyamide composite membrane with a molecular weight cut-off of 200Da and an operating pressure of 1.5MPa.

[0059] Experimental process: nuclear crystal granulation effluent → multi-media filter 5 → activated carbon filter 6 → NF membrane → test the final effluent.

[0060] According to the "Standard for Reuse of Filtrate", the following indicators are tested:

[0061] Conventional indicators: pH, suspended solids (SS), chemical oxygen demand (COD), petroleum, ammonia nitrogen, total salt content;

[0062] Ion type: Ca 2+ Mg 2+ , K + 、Na+ 、Cl - 、SO4 2- 、NO3 - ;

[0063] Heavy metals: Al 3+ 、Zn 2+ 、Mn 2+ 、Fe 3+ , total phosphorus;

[0064] Others: total nitrogen, turbidity;

[0065] The water quality standards for recycled water meet the following requirements: Ca 2+ ≤180mg / L, Mg 2+ ≤108mg / L, Zn 2+ ≤0.130mg / L, Mn 2+ ≤0.3mg / L, SO4 2- ≤250mg / L, suspended solids (SS) ≤10mg / L, chemical oxygen demand (COD) ≤100mg / L, petroleum ≤0.5mg / L, pH 6-9, total nitrogen ≤200mg / L, Fe 3+ ≤0.5mg / L, NO3 - ≤10mg / L.

[0066] Table 3 Multi-media filter treatment effect table

[0067]

[0068] Furthermore, multi-media filtration effectively reduces suspended solids and meets reuse standards.

[0069] Table 4 Activated carbon filter treatment effect table

[0070]

[0071] Furthermore, activated carbon adsorption significantly reduces COD and petroleum, meeting the reuse standards.

[0072] Table 5 NF membrane treatment effect table

[0073]

[0074] Furthermore, the NF membrane's divalent ion rejection rate: Ca 2+ (68.2%)、Mg 2+ (18.2%), SO4 2- (90.8%);

[0075] Heavy metal removal rate: Zn 2+ (82.1%)、Mn 2+ (65.7%);

[0076] pH adjustment: NF membrane concentration results in a decrease in pH, but it is still within the standard range.

[0077] Working principle: The efficient removal of calcium and magnesium ions adopts CaSO4 destabilization crystallization + Na2CO3 synergistic softening process, the calcium ion removal rate is increased to 97.3%, and the magnesium ion removal rate is 72.5%, which fully meets the NF membrane inlet water hardness requirements. After the first-level nuclear crystal granulation, the calcium concentration is reduced to 195mg / L, and further reduced to 62mg / L after NF membrane treatment, which is far below the reuse standard. The second-level nuclear crystal granulation adopts Na2S synergistic precipitation process, and the heavy metal removal rate breaks through the bottleneck of traditional technology Zn 2+ Removal rate: 98.5%, concentration after treatment: 0.05mg / L, Mn 2+ The removal rate is 91.9%, the concentration after treatment is 0.12 mg / L, and all heavy metal indicators are better than GB / T The 19923-2005 industrial reuse water standard is met. Through a combination of multi-media filtration, activated carbon adsorption, and NF membranes, COD levels are reduced from 85 mg / L to 42 mg / L, suspended solids (SS) from 243 mg / L to 5.2 mg / L, and a turbidity removal rate of 56.3%. The water quality meets the requirements for mud preparation. The monovalent salts such as NaCl and KCl retained in the filtrate can be directly used in mud preparation, saving pharmaceutical costs. The modular container skid-mounted design reduces moving costs. External wastewater discharge is reduced by 80%, along with heavy metal and COD emissions, minimizing the risk of water, soil, and groundwater pollution. The non-calcified dehydration process avoids the introduction of additional calcium ions by traditional CaO demulsifiers, reducing the rate of lost circulation accidents caused by mud denaturation at the source. 80% of the filtrate is reused in mud preparation, saving significant water resources while simultaneously recovering salts such as NaCl and KCl, achieving a closed-loop "wastewater to resource" approach.

[0078] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims, not the foregoing description, and all variations within the meaning and range of equivalents of the claims are intended to be included therein. Any reference sign in a claim should not be construed as limiting the claim to which it relates.

Claims

1. A method for harmless treatment and reuse of waste drilling fluid, characterized by: The following steps are included: S1. Non-calcified demulsification and dehydration: Add a demulsifier combination containing 1.3-1.7 g / L diatomaceous earth, 0.08-0.12 mol / L NaOH, 0.25-0.35 g / L FeCl3, and 8-12 mg / L PAM to the waste drilling hydraulic filtrate to separate the mud and water; S2, primary nucleus crystal granulation to remove calcium and magnesium: the filtrate obtained in step S1 is fed into the primary nucleus crystal granulation device, 80-120 g / L of CaSO4 is added and the pH is adjusted to 8.5-9.

5. After reacting for 2-24 hours, 0.8-1.2 mol / L of Na2CO3 and 0.15-0.25 mol / L of NaOH are added and the reaction time is 1-3 hours; S3, secondary nucleation granulation to remove heavy metals: the filtrate treated in step S2 is fed into a secondary nucleation granulation device, 1.2-1.8 mmol / L of Na2S is added and the pH is adjusted to 9.0-10.0, and the reaction time is 20-40 minutes; S4, deep filtration: the filtrate treated in step S3 is sequentially passed through a multi-media filtration, activated carbon filtration and nanofiltration (NF) membrane assembly, wherein the NF membrane operating pressure is 1.2-1.8 MPa, so that the filtrate water quality meets the reuse standard; S5. Reuse: The produced water obtained in step S4 is reused for drilling mud preparation, and the concentrated liquid is discharged for disposal.

2. The method for harmless treatment and reuse of waste drilling fluid according to claim 1, characterized in that: The demulsifying agent combination in step S1 is 1.5 g / L diatomaceous earth, 0.10 mol / L NaOH, 0.3 g / L FeCl3 and 10 mg / L PAM.

3. The method for harmless treatment and reuse of waste drilling fluid according to claim 1, characterized in that: In step S2, the dosage of CaSO4 is 100 g / L, the pH is 9, and after reacting for 24 hours, 1.0 mol / L of Na2CO3 and 0.2 mol / L of NaOH are added and reacted for 2 hours.

4. The method for harmless treatment and reuse of waste drilling fluid according to claim 1, characterized in that: In step S3, the dosage of Na2S is 1.5 mmol / L, the pH is 9.5, and the reaction is carried out for 30 minutes.

5. The method for harmless treatment and reuse of waste drilling fluid according to claim 1, characterized in that: The rejection rate of divalent ions by the NF membrane in step S4 satisfies the following conditions: 2+ Retention rate ≥65%, SO4 2- Retention rate ≥90%.

6. The method for harmless treatment and reuse of waste drilling fluid according to claim 1, characterized in that: The water quality of the recycled water in step S5 satisfies: Ca 2+ ≤180mg / L, Mg 2+ ≤108mg / L, Zn 2+ ≤0.130mg / L, Mn 2+ ≤0.3mg / L, SO4 2- ≤250mg / L, suspended solids ≤10mg / L, chemical oxygen demand (COD) ≤100mg / L, petroleum ≤0.5mg / L, pH 6-9, total nitrogen ≤200mg / L, Fe 3+ ≤0.5mg / L, NO3 - ≤10mg / L.

7. A waste drilling fluid harmless treatment and reuse system, applicable to a waste drilling fluid harmless treatment and reuse method according to any one of claims 1 to 6, characterized in that: It consists of the following modular units integrated into a container: The non-calcified demulsification unit (1) is equipped with a demulsification agent dosing device; The first-stage nucleus crystal granulation unit (2) and the second-stage nucleus crystal granulation unit (3) are connected in series and are respectively equipped with: Primary nucleus crystal granulation unit (2): CaSO4, Na2CO3, NaOH dosing system and pH adjustment device; Secondary nucleus crystal granulation unit (3): Na2S dosing system and pH adjustment device; A depth filtration unit (4), comprising, in sequence, a multi-media filter (5), an activated carbon filter (6), and a NF membrane assembly (7); A recycled water tank (8) and a concentrated liquid collection tank (9) are provided, wherein the input port of the recycled water tank (8) is connected to the water production port of the NF membrane assembly (7), and the input port of the concentrated liquid collection tank (9) is connected to the concentrated water port of the NF membrane assembly (7).

8. The waste drilling fluid harmless treatment and reuse system according to claim 7, characterized in that: The primary nucleus crystal granulation unit (2) is equipped with a pH online monitor and an automatic control system linked to the CaSO4, Na2CO3, and NaOH dosing pumps; The secondary nucleus crystal granulation unit (3) is equipped with an ORP sensor and a Na2S dosing automatic control system.

9. The waste drilling fluid harmless treatment and reuse system according to claim 7, characterized in that: The NF membrane assembly (7) is provided with an operating pressure control system and a membrane fouling monitor, and the operating pressure control system and the membrane fouling monitor are interlocked.

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