COD-containing emulsified wastewater treatment device

Abstract

The utility model discloses a kind of COD-containing emulsified wastewater treatment devices, including the adjusting pool for carrying out balance to COD-containing emulsified wastewater;With even adjusting pool is connected, for removing the oil-water separator of floatable oil in wastewater;With oil-water separator is connected, for removing the vortex concave air floatation device of dispersed oil and emulsified oil in wastewater;With vortex concave air floatation device is connected, for removing the centrifugal separator of microfine particle and heavy oil in wastewater under centrifugal action;With centrifugal separator is connected, for the heat exchanger of wastewater temperature is regulated and controlled;With heat exchanger is connected, for the ultrafiltration membrane system of wastewater is pre-filtered;With ultrafiltration membrane system is connected, for the ceramic membrane system of wastewater is fine filtered;With ceramic membrane system is connected, for the biochemical system of wastewater is biochemically treated. By multistage physical separation, membrane filtration and biochemical treatment integration, oil, suspended solids and organic matter in wastewater are effectively removed, reagent use is reduced, and operating cost is reduced.

Description

Technical Field

[0001] This utility model relates to a COD-containing emulsified wastewater treatment device, belonging to the field of wastewater treatment technology. Background Technology

[0002] With the increasing number of cars, the production of automotive parts is also growing. High-concentration emulsified wastewater from automobile manufacturing primarily originates from the painting and electrophoresis processes. This type of wastewater contains large amounts of emulsified oil and surfactants, with a COD as high as 100,000~300,000 mg / L. It is characterized by high concentration, high organic content, and deep color. The wastewater contains highly stable, water-insoluble high-molecular-weight organic substances, as well as highly dispersed, stable emulsions and numerous oily substances, making its treatment very difficult.

[0003] Current common treatment methods for this type of wastewater involve first adjusting the pH to 2-3 with acid, then adding inorganic salts (such as calcium chloride) to separate the emulsified oil from the wastewater. The oil is then separated into sludge through sedimentation or flotation processes, and the purified water is treated by anaerobic or aerobic processes to achieve compliant discharge. However, this method for treating high-COD automotive emulsified wastewater requires the addition of large amounts of chemicals for adjustment and demulsification, resulting in high chemical costs and a lack of cleanliness and environmental friendliness. Utility Model Content

[0004] The purpose of this invention is to provide a COD-containing emulsified wastewater treatment device that effectively removes oil, suspended solids and organic matter from wastewater through multi-stage physical separation, membrane filtration and biochemical treatment integration, thereby reducing the use of reagents and lowering operating costs.

[0005] The technical solution adopted in this utility model is as follows: A COD-containing emulsified wastewater treatment device, comprising: The equalization tank is used to balance the quantity and quality of COD-containing emulsified wastewater entering the tank. An oil-water separator, connected to an equalization tank, is used to remove floating oil from wastewater under gravity. The vortex-type air flotation device, connected to an oil-water separator, is used to remove dispersed oil and emulsified oil from wastewater. Centrifugal separator, connected to vortex air flotation device, is used to remove fine particles and heavy oil from wastewater under centrifugal action; The oil collection tank is connected to the oil-water separator, the vortex air flotation device, and the centrifugal separator to receive the separated waste. The heat exchanger, connected to the centrifugal separator, is used to regulate the temperature of the wastewater. An ultrafiltration membrane system, connected to a heat exchanger, is used for pre-filtration of wastewater; A ceramic membrane system, connected to an ultrafiltration membrane system, is used for fine filtration of wastewater; The biochemical system, connected to the ceramic membrane system, is used for the biochemical treatment of wastewater.

[0006] Preferably, a stirring device is provided in the equalization tank.

[0007] Preferably, a transfer pump is installed on the pipeline between the equalization tank and the oil-water separator, the pipeline between the oil-water separator and the vortex flotation device, and the pipeline between the vortex flotation device and the centrifugal separator.

[0008] Preferably, a booster pump is installed on the pipeline between the centrifuge and the heat exchanger.

[0009] Preferably, a filter is installed on the rear pipeline of the transfer pump between the equalization tank and the oil-water separator.

[0010] Preferably, the feed pipe of the oil-water separator extends into the interior of the oil-water separator, and a distributor is horizontally installed at the end of the feed pipe.

[0011] Preferably, a density difference level gauge is also installed on the oil-water separator, and a floating oil discharge valve is installed on the discharge pipe at the top of the oil-water separator.

[0012] Preferably, the concentrate side discharges of both the ultrafiltration membrane system and the ceramic membrane system are connected to the oil-water separator.

[0013] Preferably, the filtration accuracy of the membrane used in the ultrafiltration membrane system is 50-200 nm.

[0014] Preferably, the filtration accuracy of the membrane used in the ceramic membrane system is 5-20 nm.

[0015] The beneficial effects of this utility model are as follows: By integrating multi-stage physical separation, membrane filtration and biochemical treatment, it effectively removes oil, suspended solids and organic matter from wastewater, solving the technical bottlenecks of traditional methods for treating high COD emulsified wastewater, such as strong reagent dependence, high cost, easy secondary pollution and unstable operation. It is particularly suitable for high-concentration and difficult-to-degrade emulsified wastewater generated by the automobile manufacturing industry. Attached Figure Description

[0016] Figure 1 This is a connection diagram of a COD-containing emulsified wastewater treatment device.

[0017] The meanings of the main reference numerals in the figure are as follows: 1. Equalization tank; 2. Oil-water separator; 3. Vortex flotation device; 4. Centrifugal separator; 5. Oil collection tank; 6. Heat exchanger; 7. Ultrafiltration membrane system; 8. Ceramic membrane system; 9. Biochemical system; 10. Stirring device; 11. Transfer pump; 12. Filter; 13. Distributor; 14. Density difference level gauge; 15. Floating oil discharge valve; 16. Booster pump. Detailed Implementation

[0018] The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0019] Example 1: As Figure 1 As shown, this embodiment provides a COD-containing emulsified wastewater treatment device, including an equalization tank 1, an oil-water separator 2, a vortex flotation device 3, a centrifugal separator 4, an oil collection tank 5, a heat exchanger 6, an ultrafiltration membrane system 7, a ceramic membrane system 8, and a biochemical system 9.

[0020] The equalization tank 1 is used to balance the quantity and quality of COD-containing emulsified wastewater entering the tank. The discharge of high-concentration emulsified wastewater from automobile manufacturing processes is typically discontinuous and fluctuates significantly. The equalization tank 1 buffers the impact of water quantity and quality fluctuations, providing a stable and continuous influent condition for subsequent treatment systems. To improve the efficiency of water quality equalization, a stirring device 10 is also installed in the equalization tank 1.

[0021] The equalization tank 1 is connected to the oil-water separator 2 via a pipeline. A transfer pump 11 and a filter 12 (security filter) are installed sequentially along the wastewater flow direction on the pipeline. The filter 12 is equipped with a glass fiber filter element with a filtration accuracy of 5-20 μm. The homogenized wastewater in the equalization tank 1 is pumped into the security filter via the transfer pump 11. Under the action of the filter element, solid impurities in the wastewater are trapped, and the filtrate enters the oil-water separator 2.

[0022] Oil-water separator 2 is used to remove floating oil from wastewater under gravity. The feed pipe of oil-water separator 2 extends into the interior of oil-water separator 2, and a distributor 13 is horizontally installed at the end of the feed pipe. At the same time, a density difference level gauge 14 is also installed on oil-water separator 2 located above the feed pipe (near the top of oil-water separator 2), and a floating oil discharge valve 15 is installed on the discharge pipe at the top of oil-water separator 2.

[0023] Wastewater, pumped by pump 11, enters the oil-water separator 2 evenly through distributor 13. Under gravity, the wastewater separates from the floating oil. The floating oil slowly rises to the upper layer of the oil-water separator 2, while the oil-free wastewater remains at the lower layer. When the amount of floating oil reaches a certain level, i.e., when the density difference level gauge 14 rises to a designated position, the floating oil discharge valve 15 on the top discharge pipe of the oil-water separator 2 is opened to discharge the upper layer of floating oil. When the discharged floating oil reaches the designated position where the density difference level gauge 14 has fallen, the floating oil discharge valve 15 is closed, and no more floating oil is discharged.

[0024] The discharge pipe at the top of the oil-water separator 2 is connected to the oil collection tank 5, and the discharged floating oil enters the oil collection tank 5.

[0025] The drain pipe at the bottom of the oil-water separator 2 is connected to the vortex flotation device 3, and a transfer pump 11 is installed on the pipe. The vortex flotation device 3 is used to remove dispersed oil and emulsified oil from wastewater. Wastewater entering the vortex flotation device 3 is subjected to microbubbles generated by mechanical aeration, which carry away residual dispersed oil and fine emulsified oil that are difficult to separate by gravity, causing them to float to the surface. The surface oil is then scraped off by the oil skimmer attached to the vortex flotation device 3.

[0026] Similarly, the oil tank for collecting floating oil in the vortex air flotation device 3 is also connected to the oil collection tank 5 through a pipe. The floating oil flows into the oil collection tank 5 through the pipe (by different installation heights, the floating oil automatically flows into the oil collection tank 5 under the action of gravity).

[0027] The drain pipe at the bottom of the vortex flotation device 3 is connected to the centrifugal separator 4, and a transfer pump 11 is installed on the pipe. The centrifugal separator 4 is used to remove fine particles and heavy oil from the wastewater under centrifugal action. The wastewater in the vortex flotation device 3 is transported to the centrifugal separator 4 by the transfer pump 11. Utilizing the powerful centrifugal force generated by high-speed rotation, fine suspended solids, heavy oil droplets, and impurities of similar density in the wastewater are separated, achieving solid-liquid separation and a certain degree of physical demulsification.

[0028] Fine suspended solids, heavy oil droplets and impurities will overflow from the weir plate (ring) at the top of the centrifuge 4 into the collection tank. The collection tank is also connected to the oil collection tank 5 through a pipe. The waste in the collection tank flows into the oil collection tank 5 through the pipe (again, by different installation heights, the waste in the collection tank flows into the oil collection tank 5 automatically under the action of gravity).

[0029] Because the high-concentration emulsified wastewater from automobile manufacturing processes is at a relatively high temperature, even after passing through the aforementioned device, the temperature may not be able to be reduced to a suitable level. Furthermore, in order to avoid affecting the performance and lifespan of the subsequent membrane system, as well as the activity of microorganisms in the biological system 9, it is necessary to regulate the wastewater temperature to create optimal operating conditions for subsequent treatment.

[0030] The drain pipe at the bottom of the centrifuge 4 is connected to the tube side of the heat exchanger 6 and is along the direction of water flow. The tube side outlet of the heat exchanger 6 is connected to the concentration side of the ultrafiltration membrane system 7 through a pipe. The permeation side of the ultrafiltration membrane system 7 is connected to the concentration side of the ceramic membrane system 8 through a pipe. The permeation side of the ceramic membrane system 8 is connected to the biochemical system 9.

[0031] Considering that the ultrafiltration membrane system 7 and the ceramic membrane system 8 require a certain pressure to operate, a booster pump 16 is installed on the drain pipe at the bottom of the centrifuge 4. Cooling medium is introduced into the shell of the heat exchanger 6 to cool the wastewater passing through the tubes. In practical applications, a thermometer is installed on the pipe between the tube outlet of the heat exchanger 6 and the concentration side of the ultrafiltration membrane system 7 to facilitate monitoring of the regulated temperature.

[0032] After cooling, the wastewater enters the concentration side of the ultrafiltration membrane system 7. The membrane used in the ultrafiltration membrane system 7 is a PVDF membrane with a filtration accuracy of 50-200nm. The residual colloids, organic matter and extremely fine oil droplets in the wastewater are isolated on the concentration side by the membrane, while the purified liquid phase enters the permeate side and is discharged through the permeate side.

[0033] The liquid phase discharged from the permeate side of the ultrafiltration membrane system 7 enters the concentration side of the ceramic membrane system 8 through a pipeline. The ceramic membrane system 8 contains tubular ceramic membrane elements made of alumina, with a filtration accuracy of 5-20 nm, preferably 8 nm. Each membrane element is 1178 mm long and has an outer diameter of 25 mm. During operation, the pressure difference P between the inlet and outlet of the ceramic membrane system 8 is controlled to approximately 0.05-0.2 MPa (this can be achieved by installing valves on the pipeline, which is existing technology and will not be elaborated here), and the operating temperature is 20-30℃. Through the filtration pressure provided by the booster pump 16, the ceramic membrane system 8 achieves demulsification of the emulsion in the liquid phase and separation of the oil and water phases.

[0034] The concentrate from the ultrafiltration membrane system 7 and the ceramic membrane system 8 is directly connected to the feed pipe of the oil-water separator 2 downstream of the security filter via a pipeline, and is returned to the oil-water separator 2 for further recycling. The aqueous phase from the permeate side of the ceramic membrane system 8 enters the biochemical system 9.

[0035] Biological system 9 is used for the biological treatment of the incoming aqueous phase. The aqueous phase sequentially enters the anaerobic tank, anoxic tank, and aerobic tank, where it mixes with the returned sludge. Under the action of microorganisms, organic matter, phosphorus, total nitrogen, etc., are degraded into smaller molecules. The aqueous phase in the aerobic tank flows to the sedimentation tank, where sludge-water separation is achieved. The return ratio of the mixed liquor from the aerobic tank to the anoxic tank is 300%, and the return ratio of the sludge from the sedimentation tank to the anaerobic tank is 90%. The volume ratio of the three sections—anaerobic tank, anoxic tank, and aerobic tank—is 1:1.2:6.

[0036] Example 2: Treatment of COD-containing emulsified wastewater using the treatment device provided in Example 1. The COD content of the wastewater in the equalization tank is approximately 160,000 mg / L, and the wastewater temperature is adjusted to 25°C after heat exchanger control. The PVDF membrane used in the ultrafiltration system has a filtration accuracy of 100 nm, and the ceramic membrane in the ceramic membrane system has a filtration accuracy of 8 nm. The mixed liquor return ratio from the aerobic tank to the anoxic tank is 300%, and the sludge return ratio from the sedimentation tank to the anaerobic tank is 90%. The volume ratio of the anaerobic, anoxic, and aerobic tanks is 1:1.2:6. After treatment by the biological system, the effluent COD is below 50 ppm, meeting the Class I standard for COD in GB8978-1996 "Integrated Wastewater Discharge Standard".

Claims

1. A device for treating COD-containing emulsified wastewater, characterized in that, include: The equalization tank is used to balance the quantity and quality of COD-containing emulsified wastewater entering the tank. An oil-water separator, connected to an equalization tank, is used to remove floating oil from wastewater under gravity. The vortex-type air flotation device, connected to an oil-water separator, is used to remove dispersed oil and emulsified oil from wastewater. Centrifugal separator, connected to vortex air flotation device, is used to remove fine particles and heavy oil from wastewater under centrifugal action; The oil collection tank is connected to the oil-water separator, the vortex air flotation device, and the centrifugal separator to receive the separated waste. The heat exchanger, connected to the centrifugal separator, is used to regulate the temperature of the wastewater. An ultrafiltration membrane system, connected to a heat exchanger, is used for pre-filtration of wastewater; A ceramic membrane system, connected to an ultrafiltration membrane system, is used for fine filtration of wastewater; The biochemical system, connected to the ceramic membrane system, is used for the biochemical treatment of wastewater.

2. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, A stirring device is installed in the equalization tank.

3. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, Transfer pumps are installed on the pipelines between the equalization tank and the oil-water separator, between the oil-water separator and the vortex flotation device, and between the vortex flotation device and the centrifugal separator.

4. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, A booster pump is installed on the pipeline between the centrifuge and the heat exchanger.

5. The COD-containing emulsified wastewater treatment device according to claim 3, characterized in that, A filter is installed on the back end pipe of the transfer pump between the equalization tank and the oil-water separator.

6. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, The feed pipe of the oil-water separator extends into the interior of the oil-water separator, and a distributor is installed horizontally at the end of the feed pipe.

7. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, A density difference level gauge is also installed on the oil-water separator, and a floating oil discharge valve is installed on the discharge pipe at the top of the oil-water separator.

8. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, The concentrate side discharge of both the ultrafiltration membrane system and the ceramic membrane system is connected to the oil-water separator.

9. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, The filtration precision of the membranes used in the ultrafiltration membrane system is 50-200nm.

10. The COD-containing emulsified wastewater treatment device according to claim 1, characterized in that, The filtration accuracy of the membranes used in the ceramic membrane system is 5-20nm.

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