PET (Polyethylene Terephthalate) degradation system capable of realizing all-resource cyclic utilization
By combining enzymatic hydrolysis with solid-liquid separation, PTA recovery, and wastewater treatment units, the problem of PET's difficulty in degradation and recycling has been solved, achieving full resource recycling, reducing costs and the complexity of wastewater treatment, and improving the purity of PTA.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2026-03-10
AI Technical Summary
PET products are difficult to degrade naturally, and existing recycling methods are characterized by high costs, high pollution, and resource waste, especially the complex wastewater treatment generated in the chemical recycling and biodegradation post-treatment steps.
PET is degraded by enzymatic hydrolysis, and through continuous solid-liquid separation, PTA recovery and wastewater treatment units, combined with reverse osmosis and electrodialysis devices, the full resource recycling of PET is realized, including the recovery of PTA and ethylene glycol and the reuse of wastewater.
It achieves mild degradation of PET, improves the purity of PTA, reduces the difficulty and overall cost of degradation, reduces the complexity of wastewater treatment, and realizes efficient recycling of resources.
Smart Images
Figure CN223983655U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of plastic degradation and recycling technology, specifically to a PET degradation system that enables full resource recycling. Background Technology
[0002] Polyethylene terephthalate (PET) is a petroleum-based thermoplastic polymer widely used in various sectors of life, including packaging, textiles, and construction. PET products possess excellent physical and mechanical properties, as well as resistance to corrosion and high temperatures. However, because PET contains both benzene rings and ester bonds in its structure, it is difficult to be directly degraded by air or microorganisms. Despite this, the use of PET products continues to increase. This large-scale use of PET not only causes environmental pollution but also makes recycling more difficult due to the high degradation rate of PET products.
[0003] Currently, the main methods for degrading and recycling PET products include physical recycling, chemical recycling, and biodegradation recycling. Physical recycling involves mechanically crushing PET products for reprocessing or modification, but this method is less economical. Chemical recycling primarily uses depolymerization reactions to degrade PET into terephthalic acid (TPA) and ethylene glycol (EG). However, the depolymerization conditions are harsh, often involving high temperature and pressure, requiring sophisticated reaction equipment. Furthermore, the resulting TPA contains many impurities and is difficult to purify, while the EG produced has a low concentration in the reaction solution, making recycling difficult. Moreover, chemically recycled TPA is often yellow in color and has a high impurity content, failing to meet the raw material requirements for reprocessing. Therefore, the TPA obtained from chemical degradation needs to be decolorized using activated carbon, molecular sieves, etc., to obtain purified terephthalic acid (PTA), increasing recycling costs. In addition, after chemical degradation of PET, a large amount of water is needed to dissolve the obtained TPA before decolorization or purification, generating a large amount of wastewater and increasing the overall cost of PET degradation and recycling.
[0004] Given the aforementioned problems with chemical degradation of PET, biodegradation, such as enzymatic hydrolysis, has attracted increasing attention. Compared to chemical methods, enzymatic hydrolysis offers milder degradation conditions and yields higher purity PTA. However, it still generates a certain amount of saline wastewater in the post-treatment steps after the enzymatic reaction, requiring further comprehensive treatment to achieve circular production. Utility Model Content
[0005] In view of the above technical problems, this utility model provides a PET degradation system that achieves full resource recycling. The PET degradation system provided by this utility model utilizes enzymatic hydrolysis to degrade PET, and completes the recovery of PTA and ethylene glycol and the reuse of the generated wastewater through a continuous and coordinated post-treatment process, thereby achieving full resource recycling.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] This invention provides a PET degradation system for achieving full resource recycling, comprising an enzymatic hydrolysis unit, a solid-liquid separation unit, a PTA recovery unit, and a wastewater treatment unit connected in sequence. The solid-liquid separation unit includes a first filtration device, the filter cake obtained is washed with water and enters the PTA recovery unit, and the resulting first filtrate is returned to the enzymatic hydrolysis unit. The PTA recovery unit includes a filter cake dissolving device, a crystallization device, and a second filtration device. The filter cake is dissolved, crystallized, and filtered by the second filtration device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit. The wastewater treatment unit includes a reverse osmosis device and an electrodialysis device, wherein the desalinated water obtained from reverse osmosis is reused, the concentrated solution obtained from reverse osmosis enters the electrodialysis device, the acidic solution obtained from the electrodialysis device is returned to the crystallization device, and the alkaline solution obtained from the electrodialysis device is returned to the enzymatic hydrolysis unit.
[0008] In conjunction with the first aspect, in one possible implementation, the PET degradation system for achieving full resource recycling further includes an ethylene glycol recovery unit connected to the solid-liquid separation unit. When the volume concentration of ethylene glycol in the first filtrate is higher than 30%, the first filtrate enters the ethylene glycol recovery unit through a pipeline, and the substrate obtained after recovering ethylene glycol is returned to the enzymatic hydrolysis unit.
[0009] In conjunction with the first aspect, in one possible implementation, the ethylene glycol recovery unit is a distillation unit, and the ethylene glycol obtained from the distillation is used in the PET polymerization reaction.
[0010] In conjunction with the first aspect, in one possible implementation, the solid-liquid separation unit further includes a filter cake washing device, wherein the eluent obtained from washing is recovered and combined with the first filtrate.
[0011] In conjunction with the first aspect, in one possible implementation, the PTA recovery unit includes a decolorizing agent inlet and a decolorizing agent collection and filtration device on the filter cake dissolving device.
[0012] In conjunction with the first aspect, in one possible implementation, the decolorizing agent includes at least one of polyaluminum chloride, polyferric sulfate, or polyacrylamide, activated carbon, and hydrogen peroxide or sodium hypochlorite.
[0013] In conjunction with the first aspect, in one possible implementation, a concentration device is provided on the reflux pipe of the alkaline solution obtained by the electrodialysis device, and the concentrated alkaline solution is refluxed back to the enzymatic hydrolysis unit.
[0014] The beneficial effects of the PET degradation system for achieving full resource recycling provided by this utility model are as follows: Compared with the prior art, the PET degradation system provided by this utility model connects and coordinates the enzymatic hydrolysis unit, solid-liquid separation unit, PTA recovery unit, and wastewater treatment unit in sequence, enabling full resource recycling. Specifically, compared with traditional PET degradation methods and subsequent treatment methods, this utility model uses enzymatic hydrolysis to degrade PET, resulting in milder degradation conditions, lower requirements for reaction equipment, higher purity of the obtained PTA, and reduced degradation difficulty. Furthermore, this utility model applies reverse osmosis and electrodialysis devices to the PET degradation system, enabling the recovery of PTA while directly recycling the wastewater generated in subsequent treatment steps without the need for additional centralized collection and treatment. The resulting acidic and alkaline solutions can be reused within the system, greatly reducing the overall cost of enzymatic hydrolysis for PET degradation and demonstrating good application prospects. Attached Figure Description
[0015] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0016] Figure 1 The process flow diagram of the PET degradation system for realizing full resource recycling provided by this utility model is shown in the following figure: 001 is the enzymatic hydrolysis unit, 002 is the solid-liquid separation unit, 003 is the PTA recovery unit, 004 is the wastewater treatment unit, and 005 is the ethylene glycol recovery unit. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of this utility model clearer, the present utility model will be further described in detail below. It should be understood that the specific embodiments described herein are merely illustrative of the present utility model and are not intended to limit the scope of the present utility model.
[0018] Please see Figure 1The present invention provides a PET degradation system for achieving full resource recycling. This PET degradation system for achieving full resource recycling includes an enzymatic hydrolysis unit 001, a solid-liquid separation unit 002, a PTA recovery unit 003, and a wastewater treatment unit 004 connected in sequence. The solid-liquid separation unit 002 includes a first filtration device. The filter cake obtained from filtration is washed with water and enters the PTA recovery unit. The resulting first filtrate is returned to the enzymatic hydrolysis unit. The PTA recovery unit 003 includes a filter cake dissolving device, a crystallization device, and a second filtration device. The filter cake is dissolved, crystallized, and filtered by the second filtration device to obtain recovered PTA solid and a second filtrate. The second filtrate enters the wastewater treatment unit. The wastewater treatment unit 004 includes a reverse osmosis device and an electrodialysis device. The freshwater obtained from reverse osmosis is reused, and the concentrated solution obtained enters the electrodialysis device. The acidic solution obtained from the electrodialysis device is returned to the crystallization device, and the alkaline solution obtained is returned to the enzymatic hydrolysis unit 001.
[0019] The beneficial effects of the PET degradation system for achieving full resource recycling provided by this utility model are as follows: Compared with the prior art, the PET degradation system provided by this utility model connects and coordinates the enzymatic hydrolysis unit, solid-liquid separation unit, PTA recovery unit, and wastewater treatment unit in sequence, enabling full resource recycling. Specifically, compared with traditional PET degradation methods and subsequent treatment methods, this utility model uses enzymatic hydrolysis to degrade PET, which results in milder degradation conditions, lower requirements for reaction equipment, higher purity of the obtained PTA, and reduced degradation difficulty. Furthermore, this utility model applies reverse osmosis and electrodialysis devices to the PET degradation system, allowing direct recycling of wastewater generated in subsequent treatment steps without the need for additional centralized collection and treatment, greatly reducing the overall cost of the enzymatic hydrolysis PET degradation process and demonstrating good application prospects.
[0020] In some embodiments, the PET degradation system for achieving full resource recycling further includes an ethylene glycol recovery unit 005 connected to the solid-liquid separation unit 002. When the volume concentration of ethylene glycol in the first filtrate is higher than 30%, the first filtrate enters the ethylene glycol recovery unit 005 through a pipeline, and the substrate obtained after recovering the ethylene glycol is returned to the enzymatic hydrolysis unit 001. When the volume concentration of ethylene glycol in the first filtrate is less than 30%, the obtained first filtrate is directly introduced into the enzymatic hydrolysis unit 001 for circulation until the volume concentration of ethylene glycol in the obtained first filtrate is higher than 30%, at which point it is recovered.
[0021] In some embodiments, the ethylene glycol recovery unit 005 includes a distillation apparatus to recover ethylene glycol with a high concentration in the first filtrate, thus solving the problem of resource loss caused by the failure to recover ethylene glycol in existing PET degradation systems.
[0022] In some embodiments, the solid-liquid separation unit 002 further includes a filter cake washing device, wherein the eluent obtained from washing is recovered and combined with the first filtrate, and the resulting filter cake enters the PTA recovery unit 003 to recover PTA.
[0023] In some embodiments, the PTA recovery unit 003 is equipped with a decolorizing agent inlet and a decolorizing agent collection and filtration device on the filter cake dissolving device, which collects, filters and recovers the decolorizing agent, and reuses it after processing, thereby reducing degradation costs.
[0024] In some embodiments, the decolorizing agent includes at least one of polyaluminum chloride, polyferric sulfate or polyacrylamide, activated carbon, and hydrogen peroxide or sodium hypochlorite.
[0025] Existing PTA recovery processes often use activated carbon or molecular sieves for decolorization, which is costly and wasteful. This invention uses multiple reagents and employs gradient decolorization, for example, decolorizing the PTA aqueous solution in the order of polyaluminum chloride, activated carbon, and hydrogen peroxide.
[0026] In some embodiments, a concentration device is provided on the return pipe of the alkaline solution obtained by the electrodialysis device. After concentration, the alkaline solution is returned to the enzymatic hydrolysis unit 001 as an alkaline reagent for the enzymatic degradation of PET, thereby realizing the recovery of alkali from the wastewater generated by the enzymatic hydrolysis unit 001.
[0027] The above description is only a preferred embodiment of the present utility model and is not intended to limit the present utility model. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present utility model should be included within the protection scope of the present utility model.
Claims
1. A PET degradation system for achieving full resource recycling, characterized in that, The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit. The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit. The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit. The wastewater treatment unit comprises a reverse osmosis device and an electrodialysis device, wherein the fresh water obtained by reverse osmosis is reused, the concentrated liquid obtained is introduced into the electrodialysis device, the acidic solution obtained by the electrodialysis device is returned to the crystallization device, and the basic solution obtained is returned to the enzymatic hydrolysis unit.
2. The PET degradation system achieving full resource recycling utilization according to claim 1, wherein, The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit.
3. The PET degradation system achieving full resource recycling utilization according to claim 2, wherein, The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit.
4. The PET degradation system achieving full resource recycling utilization according to claim 1, wherein, The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit.
5. The PET degradation system achieving full resource recycling utilization according to any one of claims 1-4, wherein, The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit.
6. The PET degradation system achieving full resource recycling utilization according to claim 5, wherein, The PTA recovery unit comprises a filter cake dissolving device, a crystallization device and a second filtering device, the filter cake is filtered through the dissolving device, the crystallization device and the second filtering device to obtain recovered PTA solid and a second filtrate, and the second filtrate enters the wastewater treatment unit.
7. The PET degradation system achieving full resource recycling utilization according to claim 1, wherein,