CN115838217A - Integrated emulsification type oily wastewater pretreatment device and method - Google Patents

Abstract

The invention relates to an integrated emulsification type oily wastewater pretreatment device and a method, wherein the integrated emulsification type oily wastewater pretreatment device comprises a reaction tank body, a dosing system, an air flotation system and a waste storage and transportation system; the reaction tank body comprises an oil separation tank, a first regulating tank, a second regulating tank, a dissolved air flotation tank and a water production tank; the pretreatment method comprises the following steps: demulsification, coagulation aid, air flotation slag scraping, reflux and centralized treatment. The beneficial effects of the invention are: the reaction tanks are connected in series, and each reaction tank is sequentially connected with a medicament barrel and a medicament feeding pipe, so that the system has high integration degree, compact structure and good continuity; the dissolved air tank connected with the dissolved air releaser is connected with a reflux pump, so that water in the water producing pool can flow back to the dissolved air tank through a water return port; the emulsion breaking process and the air flotation process are used in series, the emulsion breaking effect is ideal, the effluent is clear and low in turbidity, and the removal rate of the water-insoluble components is high.

Description

An integrated emulsified oily wastewater pretreatment device and method

technical field

The invention relates to the technical field of water treatment, and particularly includes an integrated emulsification type oily wastewater pretreatment device and method.

Background technique

With the continuous development of human industrial level, various oil raw materials and additives are increasingly inseparable from production activities. At present, the largest amount of industrial oil such as crude oil, petroleum, diesel oil, cutting oil, etc., produces oily wastewater during use. Contains various harmful substances such as polycyclic aromatic hydrocarbons (PAHs), heavy metals, and asphaltenes.

Emulsified oily wastewater is a kind of oily wastewater. Industries such as metallurgy, chemical industry, and mechanical processing will produce a large amount of emulsified oily wastewater. The size of the oil droplets is 0-10 μm. The emulsified oil exists in the form of water in oil. Dichromic acid The salt index (C0Dcr) is generally 1000-3000mg/L, and some can reach 10000mg/L. It is relatively stable and has poor biodegradability. Its components are complex and harmful to the environment. It is one of the most difficult industrial wastewater to treat.

At present, the more mature emulsified oily wastewater treatment methods mainly include membrane filtration, coagulation sedimentation, chemical oxidation, physical adsorption separation and biochemistry. Membrane filtration technology has the advantages of simple operation process, high separation efficiency and no need to add other chemicals. However, due to the hydrophobicity of the material, it is easy to cause oil droplets to adsorb and deposit on the membrane surface during the process of treating emulsified oily wastewater, blocking the membrane pores; Coagulation-sedimentation and chemical oxidation are widely used, and the technology is mature, but a large amount of chemical reagents need to be added, which adds an additional burden to the subsequent treatment; the adsorbent used in physical adsorption separation is activated carbon, which has high adsorption efficiency, but the cost of activated carbon is high. The industrial application of this method is limited; the biochemical method is the treatment process with the lowest cost, but it also has the problems of low load limit and poor impact resistance.

In summary, how to design a device and treatment method that can realize the pretreatment of emulsified oily wastewater, thereby reducing the load of the subsequent pollutant removal process, while reducing costs and improving treatment efficiency, is an urgent problem for those skilled in the art. The problem.

Contents of the invention

The purpose of the present invention is to overcome the deficiencies in the prior art and provide an integrated emulsified oily wastewater pretreatment device and method.

This integrated emulsified oily wastewater pretreatment device includes a reaction tank body, a dosing system, an air flotation system and a waste storage and transportation system; the reaction tank body includes a grease trap, a first regulating tank, a second regulating tank, Air flotation tank and water production tank, dosing system includes demulsifier tank, coagulant tank and coagulant aid tank; air flotation system includes dissolved air tank and releaser; waste storage and transportation system includes automatic oil absorber, waste oil storage tank , slag scraper and waste slag storage tank;

Grease trap, regulating pond, regulating pond, dissolved air flotation pond and water production pond are connected in sequence; there is a water inlet on the outside of the grease trap, and a demulsifier dosing pipe and an automatic oil aspirator are provided in the grease trap, and the demulsifier is dosed The pipe is connected to the demulsifier tank, and the automatic oil absorber is connected to the waste oil storage tank; the first regulating tank is equipped with a coagulant dosing pipe, and the coagulant dosing pipe is connected to the coagulant tank; the second regulating tank is equipped with a coagulation aid agent dosing pipe, the coagulant aid dosing pipe is connected with the coagulant aid bucket;

There is a releaser in the dissolved air flotation tank, and the releaser is connected to the dissolved air tank; a slag scraper is installed on the top of the dissolved air flotation tank, and the slag scraper is connected to the waste slag storage tank; there is a return port at the bottom of the water production tank, and the return port is connected to the dissolved air tank ; The side of the water production tank is provided with a water production outlet.

As a preference: the tops of the first regulating tank and the second regulating tank are respectively provided with a first slow-speed mixer and a second slow-speed mixer, and the stirring blades of the first slow-speed mixer and the second slow-speed mixer all extend below the liquid surface.

As a preference: the dissolved air tank is connected with an air compressor; an air dissolved water pump is arranged between the releaser and the dissolved air tank, and the releaser is arranged at the bottom of the communication area between the dissolved air flotation tank and the second adjustment tank.

As a preference: the lowest part of the scraper of the slag scraper extends below the liquid level in the dissolved air flotation tank; a scum storage tank is arranged on the end partition of the slag scraper, and the scum storage tank is connected with the waste slag through pipelines and suction pumps Tank connection.

As a preference: a first dosing pump is provided between the demulsifier tank and the demulsifier dosing pipe, a second dosing pump is provided between the coagulant tank and the coagulant dosing pipe, the coagulant aid tank and the coagulation aid There is a third dosing pump between the agent dosing pipe; there is a return pump between the water return port and the dissolved air tank,

As a preference: at the end of the reaction tank, the dosing pipes for the demulsifier, the coagulant and the coagulant all extend below the liquid surface.

The method for using the integrated emulsified oily wastewater pretreatment device comprises the following steps:

S1. Demulsification: The emulsified oily wastewater first enters the grease trap from the water inlet, and the wastewater is demulsified through the demulsifier tank and the first dosing pump, and then the oil slick component is absorbed into the waste oil storage by the automatic oil absorber Can;

S2. The waste water flows into the first regulating tank by itself, and the coagulant is added to the incoming water through the coagulant tank and the second dosing pump, and stirred and mixed by the first slow mixer;

S3. The waste water flows into the second regulating tank by itself, and the coagulant is added to the incoming water through the coagulant aid tank and the third dosing pump, and stirred and mixed by the second slow speed mixer;

S4. The waste water flows into the dissolved air flotation tank by itself. The compressed air generated by the air compressor and the return water are mixed in the dissolved air tank to form dissolved air, which is then released by the dissolved air releaser into the dissolved air flotation tank for dissolved air flotation and oil removal. ;Collect the scum on the water surface of the dissolved air flotation tank through the slag scraper, and suck the scum to the waste slag storage tank through the suction pump;

S5. The waste water flows into the water production tank by itself, and part of the water produced in the water production tank is returned to the dissolved air tank by the return pump, and the other part is discharged through the water production port;

S6. Centrally process the waste oil and waste residue collected by the system.

As preferred: the demulsifier in the demulsifier tank is obtained by preparing a commercially available demulsifier as a 10-30% solution, and the dosage concentration of the first dosing pump is 20-1000ppm; the coagulant in the coagulant tank It is obtained by preparing a commercially available coagulant as a 5-10% solution, and the dosage concentration of the second dosing pump is 50-400ppm; It is obtained as a 1-2% solution, and the dosage concentration of the third dosing pump is 1-2ppm.

Preferably, in step S4: the pressure of the dissolved air tank is 3-5 bar, and the pressure of the water outlet of the dissolved air water pump is 3.5-4.5 bar.

The beneficial effects of the present invention are:

1) The multiple reaction pools of the integrated emulsified oily wastewater pretreatment device of the present invention are connected in series, and each reaction pool is connected with a chemical tank and a dosing pipe in turn. The integration is high, the structure is compact, the continuity is good, it is easy to build, and it occupies a lot of space Small, low energy consumption,.

2) In the integrated emulsified oily wastewater pretreatment device of the present invention, the wastewater in each link enters the next stage by gravity, and a dissolved air releaser is provided in the dissolved air flotation tank, and the dissolved air releaser connected The air tank is connected to the return pump, so that the water in the water production tank can return to the dissolved air tank through the water return port, which effectively reduces energy consumption and saves costs.

3) The present invention creatively uses the demulsification process and the air flotation process in series through demulsification and collection of fine oil droplets, the demulsification effect is ideal, the effluent is clear and turbid, the removal rate of non-water-soluble components is high, and the solids are suspended The removal rate of pollutants can reach 92%; the removal rate of petroleum can reach 84%, and the removal rate of animal and vegetable oil can reach 88%. Stable and sustainable, to achieve the purpose of saving costs and improving processing efficiency.

Description of drawings

Figure 1 is a schematic structural view of an integrated emulsified oily wastewater pretreatment device.

Explanation of reference numerals: grease trap 1, first regulating pond 2, second regulating pond 3, dissolved air flotation pond 4, water production pond 5, automatic oil absorber 6, first slow-speed mixer 7, second slow-speed mixer 8 , slag scraper 9, dissolved air tank 10, air compressor 11, dissolved air releaser 12, first dosing pump 13, second dosing pump 14, third dosing pump 15, return pump 16, suction pump 17. Demulsifier tank 18, waste oil storage tank 19, coagulant tank 20, coagulant aid tank 21, waste residue storage tank 22.

Detailed ways

The present invention will be further described below in conjunction with the examples. The description of the following examples is provided only to aid the understanding of the present invention. It should be pointed out that for those skilled in the art, some modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Embodiment one

As an example, as shown in Figure 1: this integrated emulsified oily wastewater pretreatment device includes a reaction tank body, a dosing system, an air flotation system, and a waste storage and transportation system. The reaction tank body includes a grease trap 1, a first adjustment tank 2, a second adjustment tank 3, a dissolved air flotation tank 4 and a water production tank 5, and the dosing system includes a demulsifier tank 18, a coagulant tank 20 and a coagulant aid tank 21. The air flotation system includes a dissolved air tank 10 and a releaser 12; the waste storage and transportation system includes an automatic oil absorber 6, a waste oil storage tank 19, a slag scraper 9 and a waste slag storage tank 22. The wastewater treatment capacity is 70m ³ /d. The bottom plate, wall plate and inner partition of the pool body are all made of 10-15mm carbon steel plate. The internal pool body is made of 316L stainless steel, and the inner surface is coated with epoxy resin paint. The size L×B×H is 13.4m×1.8m×2m, specifically: the effective length of oil trap 1 is 2.1m, the effective length of first regulating pond 2 is 1.4m, the effective length of second regulating pond 3 is 1.4m, and the dissolved air The effective length of the floating pool is 7.3m, and the effective length of the water production pool is 1.2m.

The outer side of the grease trap 1 is equipped with a water inlet, and the inner side is respectively equipped with an automatic oil absorber 6 and a demulsifier feeding pipe. The automatic oil absorber 6 is connected to the waste oil storage tank 19 through a pipeline, and the demulsifier feeding pipe passes through the first A dosing pump 13 is connected with the demulsifier bucket 18, and the dosing pipe guarantees to extend below the liquid level.

Slow speed mixer 7 and coagulant dosing pipe are equipped with respectively at the top of the first regulating tank 2, coagulant dosing pipe is connected with coagulant barrel 20 by the second dosing pump 14, and dosing pipe guarantees to extend to Below the liquid level; it is used to add coagulant to the treated water to condense the fine oil particles and suspended solids in the sewage into large oily flocs. The second slow speed mixer 8 and coagulant aid dosing pipe are equipped with respectively at the top of the second regulating tank 3, and the coagulant aid dosing pipe is connected with the coagulant aid barrel 21 by the third dosing pump 15, and the dosing pipe ensures that extend below the liquid level.

The top of the dissolved air flotation tank 4 is equipped with a slag scraper 9 and the bottom of the scraper is guaranteed to extend below the liquid level. A slot for temporarily storing scum is arranged on the end partition of the slag scraper, and the slot passes through the pipeline and the suction pump 17 is connected with waste residue storage tank 22. A dissolved air releaser 12 is installed at the bottom of the dissolved air flotation tank 4, and the dissolved air releaser 12 is connected with the dissolved air tank 10 through an air pipeline, and the dissolved air tank is provided with compressed air by an air compressor 11. The outer side of the solution pool 5 is equipped with a produced water outlet, and the bottom is equipped with a water return port, which is connected to the dissolved gas tank 10 through a return line and a return pump 16 to provide the required water source for dissolved gas.

All equipment in the device is connected with the local PLC control cabinet, and the PLC control cabinet controls the start-stop and parameter regulation of the overall device.

Embodiment two

As another embodiment, the method of the integrated emulsified oily wastewater pretreatment device proposed in Embodiment 1 is provided, which specifically includes the following steps when used:

S1. For the treatment of emulsified oily wastewater, it is first necessary to fully break the emulsion. The emulsified oily wastewater first enters the grease trap 1 from the water inlet. Emulsion, the demulsifier in the demulsifier bucket 18 is obtained by preparing a commercially available demulsifier as a 10-30% solution, and the concentration of the first dosing pump 13 is 20-1000ppm; The oil absorber 6 sucks the stratified floating oil components to the waste oil storage tank 19 .

S2. After the demulsification link is completed, the fine oil droplets are collected; since the small oil droplets are not easy to fuse with each other, the oily waste water is collected by coagulation and air flotation, and then flows into the first regulating pool 2 by itself, and passes through the coagulant tank 20 and The second dosing pump 14 completes the coagulant dosing to the incoming water, and the coagulant in the coagulant bucket 20 is obtained by preparing a commercially available coagulant as a 5% to 10% solution. The second dosing pump 14 The dosing concentration is 50-400ppm; and it is stirred and mixed by the slow mixer 7.

S3, the above-mentioned treated waste water flows further into the second regulating tank 3 by gravity, and the coagulant aid is added to the incoming water through the coagulant aid bucket 21 and the third dosing pump 15, and is stirred and mixed by the slow speed mixer 8, The coagulant aid in the coagulant aid barrel 21 is obtained by preparing a commercially available coagulant aid as a 1-2% solution, and the dosage concentration of the third dosing pump 15 is 1-2 ppm.

S4. The above-mentioned treated waste water flows further into the dissolved air flotation tank 4, and the compressed air and return water produced by the air compressor 11 are mixed in the dissolved air tank 10 to form dissolved air, and then the dissolved air installed at the bottom of the front end of the air flotation tank The release device 12 is released into the pool body, the pressure of the dissolved air tank 10 is 3-5bar, and the outlet pressure of the dissolved air water pump is 3.5-4.5bar; The dispersed oil and suspended matter condensed by the coagulant become floating matter, and the oil is removed by dissolved air flotation; the small and dense rising air bubbles lift and float the flocs formed in the front-end adjustment tank to the surface of the water body of the dissolved air flotation tank 4 and enter the air The decompression of the water releases a large number of dispersed fine bubbles; the fine bubbles collide and adhere to the flocs composed of oil and suspended matter; the adhered flocs are driven by the bubbles and float on the surface of the treated water, thereby completing the oil and suspension. The scum scraper 9 scrapes the scum to the slot where the scum is temporarily stored, and then is transferred to the waste slag storage tank 22 by the suction pump 17.

S5. The above-mentioned treated waste water flows further into the water production tank 5 by gravity. Part of the produced water in the water production tank 5 is returned to the gas dissolving tank 10 by the return pump 16 for dissolving gas, and the other part is discharged through the water production port to continue to complete the follow-up treatment. craft.

S6. Centrally process the waste oil and waste residue collected by the system.

Embodiment three

As an embodiment, the integrated emulsified oily wastewater pretreatment device and method provided in combination with Embodiment 1 and Embodiment 2 are proposed, and the wastewater is treated by the integrated emulsified oily wastewater pretreatment device described in Embodiment 1. A comparison of parameters after treatment and stable operation for 15 and 30 days is described in the table below.

It can be seen from the table that the average removal rate of petroleum is 84.2% in the first 15 days after stable operation; the average removal rate of animal and vegetable oil is 85.4%; the average removal rate of turbidity is 95.2%. The average removal rate of petroleum is 84.5% after continuous and stable operation for 30 days; the average removal rate of animal and vegetable oil is 85.7%; the average removal rate of turbidity is 96.2%.

It can be seen that the pretreatment device can effectively demulsify and remove oil from emulsified oily wastewater such as rolling water produced during the production and processing of machinery manufacturing plants. .

Embodiment four

As another example, the integrated emulsified oily wastewater pretreatment device adopted has a wastewater treatment capacity of 55m ³ /d, and the internal tank body is made of 316L stainless steel, and the inner surface is coated with epoxy resin paint. Dimensions L×B×H are 11.5m×1.8m×1.8m, specifically: the effective length of the grease trap 1 is 1.8m, the effective length of the first regulating pond 2 is 1.2m, the effective length of the second regulating pond 3 is 1.2m, and the dissolved air The effective length of the air flotation pool 4 is 6m, and the effective length of the water production pool 5 is 1.3m. The equipment is used to treat the emulsified oily wastewater produced in the process of oil processing by a petrochemical company. The demulsifier is a commercially available brand. The amount is 2ppm, and the pressure of the dissolved air tank is controlled at 4.5bar. According to the method of the integrated emulsified oily wastewater pretreatment device provided in Example 2, the parameters of the water in and out after 15 days and 30 days of stable operation of the device are respectively as follows:

As shown in the above table, the average removal rate of petroleum in the first 15 days after stable operation is 87.3%; the average removal rate of animal and vegetable oil is 86.2%; the average removal rate of turbidity is 91.7%. After 30 days of continuous and stable operation, the average removal rate of petroleum is 86.4%, the average removal rate of animal and vegetable oil is 85.9%, and the average removal rate of turbidity is 93.5%.

It can be seen that the pretreatment device can effectively demulsify and remove oil from the emulsified oily wastewater produced in the oil processing process of petrochemical enterprises.

Claims (9)

1. An integrated emulsification type oily wastewater pretreatment device is characterized in that it includes: a reaction tank body, a dosing system, an air flotation system and a waste storage and transportation system; the reaction tank body includes a grease trap (1), a first One adjustment tank (2), second adjustment tank (3), dissolved air flotation tank (4) and water production tank (5), the dosing system includes demulsifier tank (18), coagulant tank (20) and coagulation aid agent barrel (21); the air flotation system includes a dissolved air tank (10) and a releaser (12); the waste storage and transportation system includes an automatic oil absorber (6), a waste oil storage tank (19), and a slag scraper (9) And waste residue storage tank (22); Grease trap (1), regulation pond (2), regulation pond (3), dissolved air flotation pond (4) and water production pond (5) are sequentially connected; The oil pool (1) is provided with a demulsifier dosing pipe and an automatic oil aspirator (6), the demulsifier dosing pipe is connected to the demulsifier barrel (18), and the automatic oil aspirator (6) is connected to the waste oil storage tank (19); The first adjustment tank (2) is provided with a coagulant dosing pipe, which is connected to the coagulant bucket (20); the second adjustment tank (3) is provided with a coagulant dosing pipe, which aids coagulation The agent dosing pipe is connected with the coagulant aid barrel (21); The dissolved air flotation tank (4) is provided with a releaser (12), and the releaser (12) is connected to the dissolved air tank (10); the top of the dissolved air flotation tank (4) is provided with a slag scraper (9), and the slag scraper ( 9) Connecting to the waste residue storage tank (22); a water return port is provided at the bottom of the water production pool (5), and the water return port is connected to the dissolved air tank (10); the side of the water production pool (5) is provided with a water production outlet. 2. The integrated emulsified oily wastewater pretreatment device according to claim 1, characterized in that: the tops of the first regulating tank (2) and the second regulating pond (3) are respectively provided with a first slow mixer (7 ) and the second slow mixer (8), the stirring blades of the first slow mixer (7) and the second slow mixer (8) all stretch below the liquid surface. 3. The integrated emulsified oily wastewater pretreatment device according to claim 1, characterized in that: the dissolved air tank (10) is connected with an air compressor (11); the releaser (12) and the dissolved air tank (10) Dissolved air pumps are arranged between them; there is a communication port at the bottom of the inner partition between the dissolved air flotation tank (4) and the second regulating tank (3), and the release device (12) is arranged between the dissolved air flotation tank (4) and the second regulating tank (3). At the communication port of the second adjustment pool (3). 4. The integrated emulsified oily wastewater pretreatment device according to claim 1, characterized in that: the lowest part of the scraper of the slag scraper (9) extends below the liquid surface in the dissolved air flotation tank (4); The end dividing plate of machine (9) is provided with scum storage tank, and scum storage tank is connected with waste slag storage tank (22) by pipeline and suction pump (17). 5. The integrated emulsified oily wastewater pretreatment device according to claim 1, characterized in that: a first dosing pump (13) is arranged between the demulsifier bucket (18) and the demulsifier dosing pipe, and the coagulation A second dosing pump (14) is arranged between the agent barrel (20) and the coagulant dosing pipe, and a third dosing pump (15) is arranged between the coagulant aid barrel (21) and the coagulant dosing pipe. ); a return pump (16) is provided between the water return port and the dissolved air tank (10). 6. The integrated emulsified oily wastewater pretreatment device according to claim 5, characterized in that: at the end of the reaction tank, the demulsifier dosing pipe, coagulant dosing pipe and coagulant dosing pipe are all extended below the liquid level. 7. The method for using the integrated emulsification type oily wastewater pretreatment device as claimed in claim 1, is characterized in that, comprises the following steps: S1. Demulsification: The emulsified oily waste water first enters the grease trap (1) from the water inlet, and the waste water is demulsified by the demulsifier bucket (18) and the first dosing pump (13), and then the automatic oil absorber ( 6) Absorb the floating oil components to the waste oil storage tank (19); S2. The waste water enters the first regulating tank (2) by gravity, and coagulant is added to the incoming water through the coagulant bucket (20) and the second dosing pump (14), and stirred by the first slow mixer (7) mix; S3. The waste water flows into the second regulating tank (3), and the coagulant is added to the incoming water through the coagulant aid bucket (21) and the third dosing pump (15), and stirred by the second slow mixer (8) mix; S4, waste water flows into the dissolved air flotation tank (4), the compressed air produced by the air compressor (11) and the return water are mixed in the dissolved air tank (10) to form dissolved air, which is then released by the dissolved air releaser (12) to Carry out dissolved air flotation and oil removal in the dissolved air flotation tank (4); collect the scum on the surface of the water body of the dissolved air flotation tank (4) through the slag scraper (9), and suck the scum through the suction pump (17) To waste residue storage tank (22); S5. The waste water flows into the water production tank (5) by itself, and part of the produced water in the water production tank (5) is returned to the dissolved gas tank (10) by the return pump (16), and the other part is discharged through the water production port; S6. Centrally process the waste oil and waste residue collected by the system. 8. The method of using the integrated emulsification type oily wastewater pretreatment device according to claim 7, characterized in that: the demulsifier in the demulsifier tank (18) is prepared by commercially available demulsifiers to 10-30% The solution is obtained, and the dosing concentration of the first dosing pump (13) is 20-1000ppm; the coagulant in the coagulant barrel (20) is obtained by preparing a commercially available coagulant as a 5-10% solution, The dosing concentration of the second dosing pump (14) is 50～400ppm; The dosing concentration of the drug pump (15) is 1-2 ppm. 9. The method for using the integrated emulsified oily wastewater pretreatment device according to claim 7, characterized in that, in step S4: the pressure of the dissolved air tank (10) is 3 to 5 bar, and the pressure of the water outlet of the dissolved air water pump It is 3.5~4.5bar.

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