A biological treatment method for emulsified cutting waste liquid

Abstract

This invention discloses a biological treatment device and method for emulsified cutting fluid. The method employs a biochemical approach to purify the emulsified cutting fluid. First, a disc centrifuge is used for circulating filtration before biochemical treatment to achieve three-phase separation of solids, water, and oil. The solid impurity removal rate of the wastewater before biochemical treatment is ≥90%, the oil content is reduced by more than 85%, and the solid impurity filtration accuracy is higher than 2 micrometers. During the biochemical reaction, circulating filtration is stopped, and the oxygen content, temperature, and pH value in the reactor tank are adjusted in real time based on real-time wastewater parameters to improve the effect and efficiency of biochemical treatment. The treatment time is only 1 / 3 of that of traditional biochemical methods. After biochemical treatment, circulating filtration and sterilization are performed simultaneously. The solid impurity content of the treated liquid is ≤0.1%, the oil content is ≤0.5 mg / L, oil bacteria are undetectable by plate counting, and the COD content is ≤100 mg / L. Compared with traditional biochemical treatment methods, this invention significantly improves treatment efficiency and effect.

Description

Technical Field

[0001] This invention relates to a biological treatment device for emulsified cutting fluid, and also to a biological treatment method based on the above-mentioned treatment device. Background Technology

[0002] Metal cutting fluids are generally classified into three types: fully synthetic cutting fluids, semi-synthetic cutting fluids, and emulsified cutting fluids. Their base oil content varies depending on the cutting load and lubrication requirements. During metal processing, the thermal shock, mechanical shearing, and metal chips generated during cutting cause complex physicochemical reactions in the cutting fluid, leading to fluid deterioration and reduced lubrication and cooling performance.

[0003] Because cutting fluids accumulate various contaminants during operation, their lifespan is relatively short, often requiring tank replacement every 3-6 months, generating large amounts of cutting fluid waste. Emulsified cutting fluids have the highest base oil content, resulting in the most severe COD exceedances, making direct discharge into sewage networks very difficult. Currently, there are many methods for treating emulsified cutting fluid waste, which can be categorized into physical, chemical, and biological methods. Physical methods include evaporation concentration and membrane filtration; chemical methods include chemical flocculation, acid-base demulsification, and ozone oxidation; and biological methods include activated sludge processes, biofilm processes, and anaerobic biological treatment methods. CN105731706B discloses a distillation concentration method, but the concentrate still requires secondary biochemical treatment; CN111410383A discloses a composite treatment method involving demulsification + ultrafiltration + anaerobic / aerobic process + membrane bioreactor + ion exchange resin filtration, but its process flow is long and costly; CN109231722B discloses a demulsification + membrane bioreactor treatment method for emulsified wastewater, but this method requires multiple tanks for preconditioning, biological reaction, and oxidation respectively. Existing methods suffer from high treatment costs and slow treatment efficiency. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a biological treatment device with high treatment efficiency that can effectively improve the biodegradability of emulsified wastewater, and a biological treatment method based on the device.

[0005] Technical Solution: The biological treatment device for emulsified cutting waste fluid of the present invention includes a reactor tank, which is a jacketed cylindrical body. The cylindrical body includes an inner cylinder and an outer cylinder fitted outside the inner cylinder. The outer cylinder is filled with heat transfer oil. The reactor tank is equipped with a temperature sensor, a pressure sensor, a pH sensor, a dissolved oxygen sensor, and a liquid level sensor. It also includes an inlet pipe, a drain pipe, a circulation pipe, and a dosing pipe connected to the reactor tank. A tee joint is provided at the connection between the inlet pipe and the circulation pipe. The inlet pipe is equipped with a pre-filter, a solenoid valve I, and a solenoid valve III. The drain pipe is equipped with a drain pump and a drain valve. The circulation pipe is equipped with a solenoid valve II, a disc centrifuge, and an ozone generator. The dosing pipe is equipped with a flow pump I, a flow pump II, and a flow pump III.

[0006] The pre-filter is a basket filter, which performs coarse filtration of the tank liquid, with a solid impurity separation accuracy of 200μm, thus avoiding damage to the disc centrifuge caused by large-particle solid impurities or debris.

[0007] The centrifuge tank of the disc centrifuge is connected to a waste residue tank and a waste oil tank respectively. The cutting waste liquid, after being purified and separated, flows into the reactor tank after being pressurized by a centrifugal pump.

[0008] The biological treatment method based on the above-mentioned biological treatment device includes the following steps:

[0009] (1) Before the biochemical reaction, open solenoid valve I and solenoid valve III and close solenoid valve II. The waste liquid in the waste liquid tank is filtered by the pre-filter and then pumped into the reactor tank by the suction pump. When the volume of the pumped waste liquid is 1 / 2 to 2 / 3 of the inner cylinder volume of the reactor tank, stop the liquid feeding. Close solenoid valve I and solenoid valve III, open solenoid valve II and the butterfly centrifuge, turn on flow pump I, add demulsifier into the reactor tank. After the demulsification is complete, the waste liquid in the reactor tank is sucked into the butterfly centrifuge by the suction pump. The supernatant after oil and slag removal by the butterfly centrifuge is returned to the reactor tank. The circulation filtration volume is more than 10 times the inner cylinder volume of the bioreactor tank. Close solenoid valve II and the butterfly centrifuge.

[0010] (2) Start the biochemical reaction, turn on flow pump III to introduce activated sludge into the reactor tank, and at the same time turn on flow pump II to drip pH adjuster into the reactor tank to make the pH of the waste liquid 6~8. Start the heating device to make the temperature of the waste liquid 25~35℃, and use the air compressor and pressure regulating valve to make the oxygen solubility in the waste liquid 5.0~15.0mg / L; after the biochemical reaction for 2~3 days, stop the reaction.

[0011] (3) After the biochemical reaction, open the solenoid valve II, the butterfly centrifuge and the ozone generator. The waste liquid in the reactor tank is sucked into the butterfly centrifuge by the suction pump. The supernatant after oil and slag removal by the butterfly centrifuge carries ozone back to the reactor tank. The circulation filtration volume after the butterfly centrifuge is started is more than 20 times the volume of the inner cylinder of the bioreactor tank. After the circulation filtration stops, open the drain pump and drain valve to discharge the liquid in the reactor tank.

[0012] It also includes a PLC control box, and temperature sensors, pressure sensors, pH sensors, dissolved oxygen sensors, liquid level sensors, solenoid valve I, solenoid valve II, solenoid valve III, suction pump, flow pump I, flow pump II, flow pump III, heating device, disc centrifuge, ozone generator, air compressor, pressure regulating valve, drain pump and drain valve are all connected to the PLC control box.

[0013] Before the biochemical reaction, citric acid is dripped into the reactor tank via flow pump I to adjust the pH of the waste liquid to 2-4. In order to reduce the biotoxicity of the waste liquid, citric acid is used to adjust the pH of the waste liquid to 2-4, so that formaldehyde-releasing bactericides (such as BK and MBM) lose their biotoxicity, while also breaking the emulsion of the emulsion, which significantly reduces the COD in the waste liquid.

[0014] Before the biochemical reaction, the waste liquid is separated into solid, water and oil phases by a disc centrifuge. The speed of the disc centrifuge is greater than 5000 r / min and the centrifugal force generated is 6000G. After circulation filtration, the solid impurity removal rate in the waste liquid is ≥90% and the oil content in the waste liquid is reduced by more than 85%.

[0015] In step (2), the pH adjuster is triethanolamine. Triethanolamine is used to adjust the pH of the waste liquid to 6-8, providing a biological environment for bacterial reproduction and growth.

[0016] After the biochemical reaction, the waste liquid is separated into solid and liquid phases again by a butterfly centrifuge. After circulating filtration, the solid impurity content in the liquid is ≤0.1%, and the oil content is ≤0.5mg / L.

[0017] After the biochemical reaction, the liquid is simultaneously sterilized by an ozone generator during the circulating filtration process in a butterfly centrifuge. The ozone concentration is ≥0.3mg / L, and the bacteria after treatment are undetectable by plate counting method. The COD content of the liquid is ≤100mg / L.

[0018] Beneficial Effects: Compared with existing technologies, this invention has the following significant advantages: The method of this invention uses a biochemical approach to purify emulsified cutting wastewater. First, a disc centrifuge is used for circulating filtration before biochemical treatment to achieve three-phase separation of solids, water, and oil. The solid impurity removal rate of the wastewater before biochemical treatment is ≥90%, the oil content of the wastewater is reduced by more than 85%, and the filtration accuracy of solid impurities is higher than 2 microns. During the biochemical reaction, circulating filtration is stopped, and the oxygen content, temperature, and pH value in the reactor tank are adjusted in real time based on the real-time parameters of the wastewater, improving the effect and efficiency of biochemical treatment. The treatment time is only 1 / 3 of that of traditional biochemical methods. After biochemical treatment, circulating filtration and circulating sterilization are carried out simultaneously. The solid impurity content of the treated liquid is ≤0.1%, the oil content is ≤0.5mg / L, oil bacteria are undetectable by plate counting method, and the COD content is ≤100mg / L. Compared with traditional biochemical treatment methods, this invention significantly improves the treatment efficiency and effect. Attached Figure Description

[0019] Figure 1 This is a system schematic diagram of the processing device of the present invention;

[0020] Figure 2 This is a schematic diagram of the internal structure of the reactor tank. Detailed Implementation

[0021] like Figure 1As shown, the biological treatment device for emulsified cutting waste fluid of the present invention includes a reactor tank 11, which is a jacketed cylindrical body. The cylindrical body includes an inner cylinder and an outer cylinder fitted outside the inner cylinder. The outer cylinder is filled with heat-conducting oil, which is used to heat the waste fluid to provide a suitable biological reaction temperature while avoiding excessive wall temperature. The reactor tank 11 is equipped with a temperature sensor 18, a pressure sensor 12, a pH sensor 19, a dissolved oxygen sensor 20, and a liquid level sensor 22. The biological treatment device of the present invention also includes... The reactor tank 11 is connected to an inlet pipe 30, an outlet pipe 40, a circulation pipe 50, and a dosing pipe 60; a T-joint 5 is provided at the connection between the inlet pipe and the circulation pipe; a pre-filter 2, a solenoid valve I3, and a solenoid valve III31 are provided on the inlet pipe 30; an outlet pump 16 and an outlet valve 17 are provided on the outlet pipe 40; a solenoid valve II4, a butterfly centrifuge 7, and an ozone generator 10 are provided on the circulation pipe 50; and a flow pump I24, a flow pump II25, and a flow pump III26 are provided on the dosing pipe 60. The biological treatment device of the present invention also includes a PLC control box 27, a temperature sensor 18, a pressure sensor 12, a pH sensor 19, a dissolved oxygen sensor 20, a liquid level sensor 22, a solenoid valve I3, a solenoid valve II4, a solenoid valve III31, a suction pump 6, a flow pump I24, a flow pump II25, a flow pump III26, a heating device 23, a disc centrifuge 7, an ozone generator 10, an air compressor 14, a pressure regulating valve 13, a drain pump 16, and a drain valve 17, all of which are connected to the PLC control box 27.

[0022] The disc centrifuge 7 is connected to a waste residue tank 8 and a waste oil tank 9. The purified and separated cutting waste fluid is pressurized by a centrifugal pump and flows into the reactor tank 11. The floating oil coalesces and flows freely out of the drum as a light phase; particles settle inside the drum as a heavy phase. Triggered by a pressure sensor, the particles are intermittently and automatically discharged from the centrifuge tank. An ozone generator 10 is installed on the circulation pipeline at the rear end of the disc centrifuge 7. After the biochemical reaction, the waste fluid is sterilized by the disc centrifuge 7 and then enters the reactor tank 11. The ozone generator 10 continuously mixes ozone into the waste fluid for sterilization, ensuring an ozone concentration ≥0.3 mg / L. Continuous circulation ensures a sterilization rate of 99.96% before the liquid in the tank is discharged.

[0023] The pressure regulating component is integrated into the reactor tank 11. The pressure regulating component controls the oxygen concentration in the reactor tank 11 through the air compressor 14 and the nitrogen generator 15. Aeration by the nitrogen generator 15 can gradually reduce the dissolved oxygen concentration in the waste liquid, providing an environment for the growth of anaerobic bacteria, and the oxygen solubility is controlled at 0~3.0 mg / L. Aeration by the air compressor 15 can increase the oxygen concentration in the waste liquid. At the same time, the auxiliary pressure regulating valve 13 can adjust the air pressure in the reactor tank 11 to 0~0.20 MPa to increase the solubility in the waste liquid. This combination can control the oxygen solubility in the waste liquid at 5.0~15.0 mg / L.

[0024] like Figure 2 As shown, the reactor tank 11 has a tubular honeycomb carrier 29 inside its inner cylinder. The tubular honeycomb carrier 29 is fixed at the geometric center of the reactor tank 11, serving as a carrier for bacterial reproduction and growth. The aeration unit 28, with a lotus-shaped structure, is assembled at the bottom of the tubular honeycomb carrier 29 and connected to an external compressed air compressor 14 or nitrogen generator 15 via pipelines, providing the power and pressure source for aeration. The flow rate is controlled within 200 L / min to avoid large disturbances affecting bacterial attachment and growth. A drain pipe 40 is located at the bottom of the tank, controlled by a drain pump 16. The reactor tank 11 is precisely temperature-controlled by a heating device and a built-in PT100 thermal resistor (temperature sensor 18). An online pH meter 19 and an online conductivity sensor 21 can monitor the pH and conductivity of the waste liquid in real time to assist the dosing unit in adjusting the pH of the waste liquid.

[0025] The biological treatment method based on the above-mentioned biological treatment device includes the following steps:

[0026] (1) Before the biochemical reaction, open solenoid valve I3 and solenoid valve III31, and close solenoid valve II4. The waste liquid in waste liquid tank 1 is filtered by pre-filter 2 and then pumped into reactor tank 11 by suction pump 6. When the volume of the pumped waste liquid is 2 / 3 of the inner cylinder volume of reactor tank 11, stop the liquid feeding. Close solenoid valve I3 and solenoid valve III31, open solenoid valve II4 and disc centrifuge 7, turn on flow pump I24, and add citric acid into reactor tank 11 to make the pH of the waste liquid in reactor tank 11... With an H value of 3, after complete demulsification, start the disc centrifuge 7 for solid-water-oil three-phase separation. The speed of the disc centrifuge 7 must be greater than 5000 r / min, generating a centrifugal force of up to 6000G, with a solid impurity separation accuracy of 2μm. The filtered waste residue and waste oil are discharged into waste residue tank 8 and waste oil tank 9 respectively, and are collected and recycled periodically. The circulating filtration volume after starting the disc centrifuge 7 should be greater than 10 times the inner cylinder volume of the bioreactor tank 11 (if the inner cylinder volume of the bioreactor tank 11 is 10m³). 3 Therefore, the circulating filtration volume should be at least 100m³. 3To ensure that the solid impurity removal rate of the waste liquid before biochemical treatment reaches more than 90% and the oil content of the waste liquid is reduced by more than 85%, the ozone generator 10 should be kept in the off state during the filtration process before the biochemical reaction, and the solenoid valve II4 and the butterfly centrifuge 7 should be closed to end the circulation filtration.

[0027] (2) Start the biochemical reaction, turn on flow pump III26 to introduce activated sludge into reactor tank 11, and at the same time turn on flow pump II25 to drip triethanolamine into reactor tank 11 to control the pH of the waste liquid at 6~8. Start heating device 23 to control the temperature of the waste liquid at 25~35℃. Use air compressor 14, nitrogen generator 15 and pressure regulating valve 13 to keep the oxygen solubility in the waste liquid at 5~15mg / L. After the biochemical reaction lasts for 2~3 days, stop the reaction. The added activated sludge is obtained from emulsified cutting waste liquid.

[0028] (3) After the biochemical reaction is completed, adjust the pressure regulating valve 13 to the maximum opening to provide the maximum aeration volume and flush the biowax and bacteria aggregated in the reactor tank 11; restart the butterfly centrifuge 7 and start the ozone generator 10 at the same time to further separate the biowax, aggregated impurities and bacteria produced by the biochemical reaction; continuously mix ozone into the waste liquid through the ozone generator 10 for sterilization, ensuring that the ozone concentration in the waste liquid is ≥0.3mg / L, and continuously circulate to ensure that the sterilization rate reaches 99.96%; the circulation filtration volume after the butterfly centrifuge 7 is started should be greater than 20 times the inner cylinder volume of the bioreactor tank 11, and the solid impurity content after treatment should be ≤0.1%, the oil content should be ≤0.5mg / L, the bacteria should not be detected by plate counting method, and the COD content should be ≤100mg / L, meeting the national Class II water discharge standard; open the drain valve 17 and start the drain pump 16 to drain the liquid.

[0029] Table 1 compares the effectiveness of the method of this invention and the traditional biochemical method in treating emulsified cutting fluid of the same mass and composition:

[0030] .

[0031] This invention combines a bioreactor with a circulating filter to achieve solid, water, and oil phase separation before and after biochemical reactions. It reduces the biochemical difficulty of waste liquid by using demulsification and detoxification methods. During the biochemical reaction, the pH value, temperature, and oxygen content of the biochemical reaction are controlled based on real-time parameters of the wastewater, thereby significantly improving the efficiency and effectiveness of the biochemical reaction.

Claims

1. A biological treatment method for emulsified cutting waste fluid, characterized in that: The biological treatment method is implemented based on the following device, which includes a reactor tank (11), the reactor tank (11) being a jacketed cylindrical body, the cylindrical body including an inner cylinder and an outer cylinder sleeved outside the inner cylinder; the outer cylinder is filled with heat transfer oil; the reactor tank (11) is equipped with a temperature sensor (18), a pressure sensor (12), a pH sensor (19), a dissolved oxygen sensor (20), and a liquid level sensor (22); it also includes an inlet pipe (30), a drain pipe (40), and a circulation pipe (5) connected to the reactor tank (11). 0) and dosing pipeline (60); a three-way connector (5) is provided at the connection between the liquid inlet pipeline and the circulation pipeline; a pre-filter (2), solenoid valve I (3) and solenoid valve III (31) are provided on the liquid inlet pipeline (30); a drain pump (16) and a drain valve (17) are provided on the drain pipeline (40); a solenoid valve II (4), a butterfly centrifuge (7) and an ozone generator (10) are provided on the circulation pipeline (50); a flow pump I (24), a flow pump II (25) and a flow pump III (26) are provided on the dosing pipeline (60); The above-mentioned biological treatment method specifically includes the following steps: Step 1: Before the biochemical reaction, open solenoid valve I (3) and solenoid valve III (31), and close solenoid valve II (4). The waste liquid in the waste tank (1) is filtered by the pre-filter (2) and then pumped into the reactor tank (11) by the suction pump (6). When the volume of the pumped waste liquid is 1 / 2 to 2 / 3 of the inner cylinder volume of the reactor tank (11), stop the liquid feeding. Close solenoid valve I (3) and solenoid valve III (31), open solenoid valve II (4) and the disc centrifuge (7), turn on the flow pump I (24), and add citric acid into the reactor tank (11) to make the waste liquid in the reactor tank (11) circulate. The pH value of the liquid is 3. After complete demulsification, the waste liquid in the reactor tank (11) is sucked into the butterfly centrifuge (7) by the suction pump (6). The supernatant after oil and slag removal by the butterfly centrifuge (7) is returned to the reactor tank (11). The circulating filtration volume is more than 10 times the inner cylinder volume of the bioreactor tank (11) to ensure that the solid impurity removal rate of the waste liquid before biochemical treatment reaches more than 90% and the oil content of the waste liquid is reduced by more than 85%. During the filtration process before biochemical reaction, the ozone generator (10) should be kept in the closed state. The solenoid valve II (4) and the butterfly centrifuge (7) are closed, and the circulating filtration ends. Step 2: Start the biochemical reaction. Turn on flow pump III (26) to introduce activated sludge into reactor tank (11). At the same time, turn on flow pump II (25) to drip pH adjuster into reactor tank (11) to make the pH of waste liquid 6~8. Start heating device (23) to make the temperature of heat transfer oil 25~35℃. Use air compressor (14), nitrogen generator (15) and pressure regulating valve (13) to make the oxygen solubility in waste liquid 5.0~15.0mg / L. After 2~3 days of biochemical reaction, stop the reaction. Step 3: After the biochemical reaction is completed, open the solenoid valve II (4), the butterfly centrifuge (7) and the ozone generator (10). The waste liquid in the reactor tank (11) is sucked into the butterfly centrifuge (7) by the suction pump (6). The supernatant after oil and slag removal by the butterfly centrifuge (7) carries ozone back to the reactor tank (11) to ensure that the ozone concentration in the waste liquid is ≥0.3mg / L. The continuous circulation ensures that the sterilization rate reaches 99.96%. The circulation filtration volume after the butterfly centrifuge (7) is started is more than 20 times the inner cylinder volume of the bioreactor tank (11). After treatment, the solid impurity content is ≤0.1%, the oil content is ≤0.5mg / L, the bacteria cannot be detected by plate counting method, and the COD content is ≤100mg / L. After the circulation filtration stops, open the drain pump (16) and the drain valve (17) to discharge the liquid in the reactor tank (11).

2. The biological treatment method for emulsified cutting waste fluid according to claim 1, characterized in that: It also includes a PLC control box (27), a temperature sensor (18), a pressure sensor (12), a pH sensor (19), a dissolved oxygen sensor (20), a liquid level sensor (22), a solenoid valve I (3), a solenoid valve II (4), a solenoid valve III (31), a suction pump (6), a flow pump I (24), a flow pump II (25), a flow pump III (26), a heating device (23), a butterfly centrifuge (7), an ozone generator (10), an air compressor (14), a pressure regulating valve (13), a drain pump (16), and a drain valve (17), all of which are connected to the PLC control box (27).

3. The biological treatment method for emulsified cutting waste fluid according to claim 1, characterized in that: The centrifuge tank of the butterfly centrifuge (7) is connected to a waste residue tank (8) and a waste oil tank (9). The purified and separated cutting waste liquid flows into the reactor tank (11) after being pressurized by a centrifugal pump.

4. The biological treatment method for emulsified cutting waste fluid according to claim 1, characterized in that: The pre-filter (2) is a basket filter, which performs coarse filtration of the tank liquid, and the separation accuracy of solid impurities is not less than 200μm.

5. The biological treatment method for emulsified cutting waste fluid according to claim 1, characterized in that: Before the biochemical reaction, the waste liquid is separated into solid, water and oil phases by a butterfly centrifuge (7). The speed of the butterfly centrifuge (7) is greater than 5000 r / min, and the centrifugal force generated is 6000 G.

6. The biological treatment method for emulsified cutting waste fluid according to claim 1, characterized in that: In step 2, the pH adjuster is triethanolamine.

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