Esterification wastewater treatment device

Abstract

The utility model provides an esterification wastewater treatment device and relates to the technical field of water treatment. The utility model provides an esterification wastewater treatment device which comprises an adjusting tank, a forward osmosis device, an acetaldehyde recovery device, an ethylene glycol recovery device, a biochemical treatment tank, a first-stage reverse osmosis device and a second-stage reverse osmosis device. According to the device, a forward osmosis process is added before a reverse osmosis process, so that the pollution blocking risk of a reverse osmosis membrane is reduced, the operation energy consumption can be reduced, the acetaldehyde content in the wastewater can be increased from 8740mg / L to 22900mg / L, and the concentrated esterification wastewater enters the ethylene glycol and acetaldehyde recovery device, so that the cost of a gas stripping process can be greatly reduced; therefore, the purposes of zero discharge of waste water and waste turning into wealth are achieved.

Description

Technical Field

[0001] The utility model relates to the technical field of water treatment, in particular to a treatment device for esterification wastewater. Background Art

[0002] Polyester (PET) is a high-molecular-weight polymer produced through the esterification and polycondensation of purified terephthalic acid (PTA) and ethylene glycol (EG). The esterification reaction in polyester production produces wastewater containing organic matter, with COD values ​​typically ranging from 20,000 to 30,000 mg / L. This wastewater typically contains small amounts of organic compounds such as EG, acetaldehyde, and dimethyl-1,3-dioxolane, with the concentrations of these three major organic compounds typically ranging from 0.2% to 2.0%.

[0003] The current treatment method in the domestic industry is to concentrate wastewater using a reverse osmosis system and then perform gas stripping. The esterification waste gas, rich in acetaldehyde and ethylene glycol, is then sent to a heat transfer furnace for incineration as fuel. However, this is not an economical method. Acetaldehyde, second only to formaldehyde in industrial value, is primarily used to produce acetic acid and its derivatives, acetone, and various other organic compounds. Furthermore, acetaldehyde is relatively expensive on the market. Extracting acetaldehyde from wastewater could, on the one hand, reduce the COD content in polyester wastewater to below 3000 mg / L, improving the company's environmental performance; on the other hand, recovered acetaldehyde and ethylene glycol can be recycled, bringing significant economic benefits to the company.

[0004] In view of this, the present utility model is proposed. Utility Model Content

[0005] The purpose of the utility model is to provide a treatment device for esterification wastewater to solve the above problems.

[0006] In order to achieve the above objectives, the following technical solutions are adopted:

[0007] In a first aspect, the utility model provides a treatment device for esterification wastewater, comprising: a regulating tank, a forward osmosis device, an acetaldehyde recovery device, an ethylene glycol recovery device, a biochemical treatment tank, a first-stage reverse osmosis device, and a second-stage reverse osmosis device;

[0008] Along the water treatment direction, the regulating tank, forward osmosis device, acetaldehyde recovery device, ethylene glycol recovery device and biochemical treatment tank are connected in sequence, and the regulating tank, forward osmosis device, first-stage reverse osmosis device and second-stage reverse osmosis device are connected in sequence;

[0009] The regulating tank is used to provide the esterification wastewater to the forward osmosis device;

[0010] The concentrated water outlet of the forward osmosis device is connected to the water inlet of the acetaldehyde recovery device, and the produced water outlet is connected to the water inlet of the first-stage reverse osmosis device;

[0011] The acetaldehyde recovery device is used to recover acetaldehyde in wastewater and provide the treated wastewater to the ethylene glycol recovery device;

[0012] The ethylene glycol recovery device is used to recover ethylene glycol in wastewater and provide the treated wastewater to the biochemical treatment pool;

[0013] The biochemical treatment pool is used to perform biochemical treatment on wastewater;

[0014] The water outlet of the first-stage reverse osmosis device is connected to the water inlet of the second-stage reverse osmosis device, and the concentrated water outlet is connected to the draw liquid inlet of the forward osmosis device;

[0015] The concentrated water outlet of the second-stage reverse osmosis device is communicated with the water inlet of the first-stage reverse osmosis device.

[0016] As a further technical solution, an agitator is provided in the regulating tank;

[0017] The agitator is used for homogenizing the esterification wastewater.

[0018] As a further technical solution, the regulating tank is further provided with a coarse grid;

[0019] The coarse screen is used to intercept large suspended solids in the esterification wastewater.

[0020] As a further technical solution, a filtration tank is further provided between the regulating tank and the forward osmosis device;

[0021] The filter tank is used to filter the esterification wastewater from the regulating tank and provide the filtered wastewater to the forward osmosis device.

[0022] As a further technical solution, the acetaldehyde recovery device includes a stripping tower and a distillation tower.

[0023] As a further technical solution, the ethylene glycol recovery device includes a distillation tower.

[0024] In this solution, the working principle of the acetaldehyde recovery device mainly involves the steps of esterification water stripping, acetaldehyde distillation and ethylene glycol purification. These steps together ensure the efficient recovery and purification of acetaldehyde.

[0025] Esterification water stripping:

[0026] During the esterification water stripping process, process wastewater is stripped with steam, allowing most of the acetaldehyde in the wastewater to be discharged through the top of the stripping tower, forming a mixed tail gas of acetaldehyde and water vapor. After the tail gas is condensed in a condenser, the condensate is sent to the acetaldehyde distillation tower for further treatment.

[0027] Acetaldehyde distillation:

[0028] During the acetaldehyde distillation stage, the condensate is fed into a distillation tower for distillation. The tower's operating conditions, including a specific reflux ratio and operating pressure, ensure that a mass fraction of greater than 98% industrial acetaldehyde is obtained at the top of the tower. Simultaneously, the acetaldehyde-ethylene glycol complex partially decomposes in the tower, producing acetaldehyde and ethylene glycol.

[0029] Ethylene glycol purification:

[0030] The lower concentration of ethylene glycol aqueous solution obtained in the tower is then distilled and purified in the ethylene glycol purification tower to further improve the purity and quality of the ethylene glycol. This step ensures the quality and purity of the final product.

[0031] Through the above steps, the acetaldehyde recovery device can efficiently recover and purify acetaldehyde while reducing environmental pollution, meeting the requirements of energy conservation and emission reduction.

[0032] As a further technical solution, a wastewater collection tank is further provided between the ethylene glycol recovery device and the biochemical treatment tank;

[0033] The wastewater collection tank is used to collect wastewater treated by the ethylene glycol recovery device and provide the collected wastewater to the biochemical treatment tank.

[0034] As a further technical solution, the biochemical treatment tank includes a hydrolysis acidification tank, an anaerobic tank, a contact oxidation tank, an aerobic tank and an MBR tank;

[0035] The water outlet of the biochemical treatment pool is communicated with the water inlet of the second-stage reverse osmosis device.

[0036] As a further technical solution, it also includes a water production pool;

[0037] The water production pool is used to collect the water produced by the second-stage reverse osmosis device.

[0038] As a further technical solution, a filter press is also included for dewatering the sludge in the biochemical treatment tank;

[0039] The drain outlet of the filter press is communicated with the water inlet of the biochemical treatment tank.

[0040] Compared with the prior art, the present invention has the following beneficial effects:

[0041] 1. Add a forward osmosis system before reverse osmosis to reduce the fouling of the reverse osmosis membrane by high COD wastewater, extend the service life of the reverse osmosis membrane, and reduce the operating costs of the enterprise;

[0042] 2. The forward osmosis flux is greater than that of the reverse osmosis system, and forward osmosis is easy to clean and not prone to fouling and clogging, which speeds up the recovery of acetaldehyde, increases production capacity for enterprises, and creates profits;

[0043] 3. The forward osmosis system does not require pressurization, has low operating costs, and has low safety risks;

[0044] 4. Achieve zero discharge of esterification wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] In order to more clearly illustrate the specific implementation methods of the utility model or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0046] Figure 1 The device for treating esterification wastewater provided in Example 1 of the present utility model;

[0047] Figure 2 This is a device for treating esterification wastewater provided in Example 2 of the present utility model.

[0048] Icons: 1-regulating tank; 2-forward osmosis device; 3-acetaldehyde recovery device; 4-ethylene glycol recovery device; 5-biochemical treatment tank; 6-first stage reverse osmosis device; 7-second stage reverse osmosis device; 8-filtration tank; 9-wastewater collection tank; 10-water production tank; 11-filter press. DETAILED DESCRIPTION

[0049] The following embodiments of the present invention will be described in detail with reference to the embodiments and examples. However, those skilled in the art will understand that the following embodiments and examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0050] In view of the characteristics of esterification wastewater, high COD esterification wastewater is prone to cause fouling and clogging of reverse osmosis membranes, reducing the service life of reverse osmosis membranes and increasing enterprise operating costs. The following technical solutions are proposed:

[0051] The utility model provides a device for treating esterification wastewater, such as Figure 1 or Figure 2 As shown, it includes: a regulating tank 1, a forward osmosis device 2, an acetaldehyde recovery device 3, an ethylene glycol recovery device 4, a biochemical treatment tank 5, a first-stage reverse osmosis device 6 and a second-stage reverse osmosis device 7;

[0052] Along the water treatment direction, the regulating tank 1, the forward osmosis device 2, the acetaldehyde recovery device 3, the ethylene glycol recovery device 4 and the biochemical treatment tank 5 are connected in sequence, and the regulating tank 1, the forward osmosis device 2, the first-stage reverse osmosis device 6 and the second-stage reverse osmosis device 7 are connected in sequence;

[0053] The regulating tank 1 is used to stabilize water quality and provide esterification wastewater to the forward osmosis device 2;

[0054] The concentrated water outlet of the forward osmosis device 2 is connected to the water inlet of the acetaldehyde recovery device 3, and the produced water outlet is connected to the water inlet of the first-stage reverse osmosis device 6;

[0055] The acetaldehyde recovery device 3 is used to recover acetaldehyde in the wastewater and provide the treated wastewater to the ethylene glycol recovery device 4;

[0056] The ethylene glycol recovery device 4 is used to recover ethylene glycol in the wastewater and provide the treated wastewater to the biochemical treatment tank 5;

[0057] The biochemical treatment pool 5 is used to perform biochemical treatment on wastewater;

[0058] The water outlet of the first-stage reverse osmosis device 6 is connected to the water inlet of the second-stage reverse osmosis device 7, and the concentrated water outlet is connected to the draw liquid inlet of the forward osmosis device 2;

[0059] The concentrated water outlet of the second-stage reverse osmosis device 7 is communicated with the water inlet of the first-stage reverse osmosis device 6 .

[0060] In view of the shortcomings of the existing technology, the utility model adds a forward osmosis process before the reverse osmosis process, which not only reduces the risk of fouling and clogging of the reverse osmosis membrane, but also reduces the operating energy consumption. The acetaldehyde content in the wastewater can be increased from 8740 mg / L to 22900 mg / L, and the concentrated esterification wastewater is then fed into the ethylene glycol and acetaldehyde recovery device, which can greatly reduce the cost of the gas stripping process, thereby achieving the goal of zero wastewater discharge and turning waste into treasure.

[0061] In some optional embodiments, a stirrer is provided in the regulating tank 1;

[0062] The agitator is used to homogenize the esterification wastewater. The homogenization process maintains the stability of the oily wastewater from electronic cleaning and reduces the impact of water fluctuations on the system.

[0063] In some optional embodiments, the regulating tank 1 is further provided with a coarse grid;

[0064] The coarse screen is used to intercept large suspended solids in the esterification wastewater.

[0065] In some optional embodiments, a filtration tank 8 is further provided between the regulating tank 1 and the forward osmosis device 2;

[0066] The filter tank 8 is used to filter the esterification wastewater from the regulating tank 1 and provide the filtered wastewater to the forward osmosis device 2 .

[0067] In some optional embodiments, the acetaldehyde recovery device 3 includes a stripping tower and a distillation tower.

[0068] In some optional embodiments, the ethylene glycol recovery device 4 includes a distillation column.

[0069] In some optional embodiments, a wastewater collection tank 9 is further provided between the ethylene glycol recovery device 4 and the biochemical treatment tank 5;

[0070] The wastewater collection tank 9 is used to collect wastewater treated by the ethylene glycol recovery device 4 and provide the collected wastewater to the biochemical treatment tank 5 .

[0071] The wastewater treated by the ethylene glycol recovery device 4 may have a relatively high temperature. The wastewater temperature can be lowered by the wastewater collection tank 9 before being supplied to the biochemical treatment tank 5 .

[0072] In some optional embodiments, the biochemical treatment tank 5 includes a hydrolysis acidification tank, an anaerobic tank, a contact oxidation tank, an aerobic tank and an MBR tank;

[0073] The water outlet of the biochemical treatment pool 5 is communicated with the water inlet of the second-stage reverse osmosis device 7 .

[0074] In some optional embodiments, a water production pool 10 is further included;

[0075] The water production pool 10 is used to collect the water produced by the second-stage reverse osmosis device 7. The produced water is directly discharged to the outside or reused in the factory.

[0076] In some optional embodiments, a filter press 11 is further included to dewater the sludge in the biochemical treatment tank 5;

[0077] The drain outlet of the filter press 11 is connected to the water inlet of the biochemical treatment tank 5 .

[0078] The present invention is further described below through specific examples. However, it should be understood that these examples are only used for more detailed description and should not be understood as limiting the present invention in any form.

[0079] Example 1

[0080] An esterification wastewater treatment device, as shown in Figure 1, includes: a regulating tank 1, a forward osmosis device 2, an acetaldehyde recovery device 3, an ethylene glycol recovery device 4, a biochemical treatment tank 5, a first-stage reverse osmosis device 6 and a second-stage reverse osmosis device 7;

[0081] Along the water treatment direction, the regulating tank 1, the forward osmosis device 2, the acetaldehyde recovery device 3, the ethylene glycol recovery device 4 and the biochemical treatment tank 5 are connected in sequence, and the regulating tank 1, the forward osmosis device 2, the first-stage reverse osmosis device 6 and the second-stage reverse osmosis device 7 are connected in sequence;

[0082] The regulating tank 1 is used to provide the homogenized esterification wastewater to the forward osmosis device 2;

[0083] The concentrated water outlet of the forward osmosis device 2 is connected to the water inlet of the acetaldehyde recovery device 3, and the produced water outlet is connected to the water inlet of the first-stage reverse osmosis device 6;

[0084] The acetaldehyde recovery device 3 is used to recover acetaldehyde in the wastewater and provide the treated wastewater to the ethylene glycol recovery device 4;

[0085] The ethylene glycol recovery device 4 is used to recover ethylene glycol in the wastewater and provide the treated wastewater to the biochemical treatment tank 5;

[0086] The biochemical treatment pool 5 is used to perform biochemical treatment on wastewater;

[0087] The water outlet of the first-stage reverse osmosis device 6 is connected to the water inlet of the second-stage reverse osmosis device 7, and the concentrated water outlet is connected to the drawn liquid inlet of the forward osmosis device 2;

[0088] The concentrated water outlet of the second-stage reverse osmosis device 7 is communicated with the water inlet of the first-stage reverse osmosis device 6 .

[0089] Example 2

[0090] A treatment device for esterification wastewater, such as Figure 2 As shown, it includes: a regulating tank 1, a forward osmosis device 2, an acetaldehyde recovery device 3, an ethylene glycol recovery device 4, a biochemical treatment tank 5, a first-stage reverse osmosis device 6, a second-stage reverse osmosis device 7, a filter tank 8, a wastewater collection tank 9, a filter press 11 and a water production tank 10;

[0091] Along the water treatment direction, the regulating tank 1, the filter tank 8, the forward osmosis device 2, the acetaldehyde recovery device 3, the ethylene glycol recovery device 4, the wastewater collection tank 9 and the biochemical treatment tank 5 are connected in sequence, and the regulating tank 1, the filter tank 8, the forward osmosis device 2, the first-stage reverse osmosis device 6, the second-stage reverse osmosis device 7 and the water production tank 10 are connected in sequence;

[0092] The regulating tank 1 is used to provide the esterification wastewater to the forward osmosis device 2; the regulating tank 1 is provided with an agitator and a coarse screen; the agitator is used to homogenize the esterification wastewater; the coarse screen is used to intercept large suspended particles in the esterification wastewater;

[0093] The concentrated water outlet of the forward osmosis device 2 is connected to the water inlet of the acetaldehyde recovery device 3, and the produced water outlet is connected to the water inlet of the first-stage reverse osmosis device 6;

[0094] The acetaldehyde recovery device 3 is a stripping tower and a distillation tower connected in sequence, which are used to recover acetaldehyde in the wastewater and provide the treated wastewater to the ethylene glycol recovery device 4;

[0095] The ethylene glycol recovery device 4 is a distillation tower for recovering ethylene glycol from wastewater and providing the treated wastewater to the wastewater collection tank 9;

[0096] The wastewater collection tank 9 is used to collect the wastewater treated by the ethylene glycol recovery device 4 and provide the collected wastewater to the biochemical treatment tank 5;

[0097] The biochemical treatment tank 5 includes a hydrolysis acidification tank, an anaerobic tank, a contact oxidation tank, an aerobic tank and an MBR tank in sequence, and is used to biochemically treat the wastewater; the water outlet of the biochemical treatment tank 5 is connected to the water inlet of the second-stage reverse osmosis device 7;

[0098] The water outlet of the first-stage reverse osmosis device 6 is connected to the water inlet of the second-stage reverse osmosis device 7, and the concentrated water outlet is connected to the drawn liquid inlet of the forward osmosis device 2;

[0099] The concentrated water outlet of the second-stage reverse osmosis device 7 is connected to the water inlet of the first-stage reverse osmosis device 6;

[0100] The filter press 11 is used to dehydrate the sludge in the biochemical treatment tank 5; the drain outlet of the filter press 11 is connected to the water inlet of the biochemical treatment tank 5;

[0101] The water production pool 10 is used to collect the water produced by the second-stage reverse osmosis device 7 .

[0102] The working process is as follows:

[0103] The esterification wastewater is filtered through a coarse screen and flows into a regulating tank for homogenization treatment. It then passes through a filter tank 8 to remove suspended particles, is concentrated through a forward osmosis device 2, recovers acetaldehyde through an acetaldehyde recovery device 3 (the stripping tower temperature is 125°C-135°C), and recovers ethylene glycol through an ethylene glycol recovery device 4. The wastewater treated by the ethylene glycol recovery device 4 is collected through a wastewater collection tank 9 and supplied to a biochemical treatment tank 5 for biochemical treatment. The sludge in the biochemical treatment tank 5 is transported to a filter press 11 for dehydration treatment, and the dehydrated water is returned to the biochemical treatment tank 5 for biochemical treatment again.

[0104] The produced water of the forward osmosis device 2 is purified by the first-stage reverse osmosis device 6 (with a pressure of 40 bar) and the second-stage reverse osmosis device 7 (with a pressure of 10 bar) in sequence, and the obtained produced water is collected in the produced water pool 10.

[0105] After testing, it was found that the acetaldehyde content in the wastewater was increased from 8740 mg / L to 22900 mg / L after treatment with the forward osmosis device.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A treatment device for esterification wastewater, characterized in that: include: A regulating tank (1), a forward osmosis device (2), an acetaldehyde recovery device (3), an ethylene glycol recovery device (4), a biochemical treatment tank (5), a first-stage reverse osmosis device (6), and a second-stage reverse osmosis device (7); Along the water treatment direction, the regulating tank (1), the forward osmosis device (2), the acetaldehyde recovery device (3), the ethylene glycol recovery device (4) and the biochemical treatment tank (5) are sequentially connected, and the regulating tank (1), the forward osmosis device (2), the first-stage reverse osmosis device (6) and the second-stage reverse osmosis device (7) are sequentially connected; The regulating tank (1) is used to provide esterification wastewater to the forward osmosis device (2); The concentrated water outlet of the forward osmosis device (2) is connected to the water inlet of the acetaldehyde recovery device (3), and the produced water outlet is connected to the water inlet of the first-stage reverse osmosis device (6); The acetaldehyde recovery device (3) is used to recover acetaldehyde in the wastewater and provide the treated wastewater to the ethylene glycol recovery device (4); The ethylene glycol recovery device (4) is used to recover ethylene glycol from the wastewater and provide the treated wastewater to the biochemical treatment tank (5); The biochemical treatment pool (5) is used to perform biochemical treatment on wastewater; The water outlet of the first-stage reverse osmosis device (6) is connected to the water inlet of the second-stage reverse osmosis device (7), and the concentrated water outlet is connected to the drawn liquid inlet of the forward osmosis device (2); The concentrated water outlet of the second-stage reverse osmosis device (7) is communicated with the water inlet of the first-stage reverse osmosis device (6).

2. The processing device according to claim 1, characterized in that The regulating tank (1) is provided with an agitator; The agitator is used for homogenizing the esterification wastewater.

3. The processing device according to claim 1, characterized in that The regulating tank (1) is further provided with a coarse grid; The coarse screen is used to intercept large suspended solids in the esterification wastewater.

4. The processing device according to claim 1, characterized in that A filter tank (8) is further provided between the regulating tank (1) and the forward osmosis device (2); The filtering tank (8) is used to filter the esterification wastewater from the regulating tank (1) and provide the filtered wastewater to the forward osmosis device (2).

5. The processing device according to claim 1, characterized in that The acetaldehyde recovery device (3) comprises a stripping tower and a distillation tower.

6. The processing device according to claim 1, characterized in that The ethylene glycol recovery device (4) includes a distillation tower.

7. The processing device according to claim 1, characterized in that A wastewater collection tank (9) is also provided between the ethylene glycol recovery device (4) and the biochemical treatment tank (5); The wastewater collection tank (9) is used to collect wastewater treated by the ethylene glycol recovery device (4) and provide the collected wastewater to the biochemical treatment tank (5).

8. The processing device according to claim 1, characterized in that The biochemical treatment tank (5) includes a hydrolysis acidification tank, an anaerobic tank, a contact oxidation tank, an aerobic tank and an MBR tank; The water outlet of the biochemical treatment pool (5) is in communication with the water inlet of the second-stage reverse osmosis device (7).

9. The processing device according to claim 1, characterized in that Also included is a water production pool (10); The water production pool (10) is used to collect the water produced by the second-stage reverse osmosis device (7).

10. The processing device according to claim 1, characterized in that It also includes a filter press (11) for dewatering the sludge in the biochemical treatment tank (5); The drain outlet of the filter press (11) is communicated with the water inlet of the biochemical treatment tank (5).

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