Biomass-to-methanol wastewater treatment system

Abstract

The invention provides a wastewater treatment system for preparing methanol from biomass. The wastewater treatment system comprises a polyimide monomer wastewater pretreatment system, a biochemical treatment system and a membrane system, the polyimide monomer wastewater pretreatment system comprises a wastewater collection tank, a low-temperature evaporation device, an ethanol collection tank and a concentrated water collection tank; an inlet of the wastewater collection tank is connected with a polyimide monomer wastewater discharge pipe, an outlet of the wastewater collection tank is connected with an inlet of the low-temperature evaporation device, a first outlet of the low-temperature evaporation device is connected with the concentrated water collection tank, and a second outlet of the low-temperature evaporation device is connected with the ethanol collection tank; an outlet of the ethanol collecting tank is connected with the homogenizing tank; according to the invention, heat pump evaporation and application of a gas separation membrane are combined, organic solvents and salts in the PI monomer wastewater are separated from water and ethanol, and the problems that the COD content of the PI monomer wastewater is high, the PI monomer wastewater contains a large amount of organic solvents and salts, and the biodegradability of the wastewater is extremely poor are solved; meanwhile, resource recycling of the ethanol is realized.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more particularly to a biomass-to-methanol wastewater treatment system. Background Technology

[0002] The production of carbon-footprint-free green alcohol-based fuels from biomass for use in shipping and vehicle transportation is of great significance to the global shipping and automotive industries. Currently, technologies such as renewable resource gasification, CO / H2 separation, one-carbon chemistry, hydrogenation, and gas-phase carbonylation for producing green electrolyte solvents are being developed both domestically and internationally. These technologies utilize biomass and pre-treated municipal waste or industrial waste as raw materials to produce high-end and in-demand chemical products such as PI (polyimide) and green alcohol-based fuels after gasification. The production process generates a large amount of high-concentration organic wastewater and wastewater from the circulating water station. After treatment, the wastewater is recycled, and the concentrated wastewater meets the requirements for municipal sewer system discharge and can be discharged to the industrial park's wastewater treatment plant.

[0003] Currently, wastewater treatment for biomass-based methanol production mainly employs traditional processes. For PI monomer wastewater, methods such as coagulation sedimentation and activated carbon adsorption are commonly used to attempt to reduce COD and remove some organic matter and salts, but the effects are limited, and the wastewater's biodegradability remains poor. For black and grey water treatment, suspended solids are first removed through coagulation sedimentation before entering a biological treatment system for carbon and nitrogen removal. Due to the high ammonia nitrogen content and C:N ratio imbalance of 2 in black and grey water, additional carbon sources are needed to ensure the effectiveness of biological nitrogen removal. As for wastewater reuse, it is mostly achieved by mixing biological effluent with circulating wastewater, then subjecting it to hardness removal via a dual-alkali process, followed by purification through a multi-media filter, ultrafiltration, and reverse osmosis system. The recovery rate is approximately 75%, and the remaining concentrated water is simply treated to meet standards before being directly discharged.

[0004] However, existing technologies have many drawbacks. When treating PI monomer wastewater, traditional methods struggle to effectively separate organic solvents and salts, resulting in incomplete COD removal and persistent problems with poor wastewater biodegradability. Furthermore, valuable components such as ethanol cannot be recovered, leading to resource waste. In the black and grey water treatment stage, purchasing external carbon sources not only increases costs but also complicates the process. Regarding wastewater reuse, the concentrate from the reverse osmosis system is not deeply treated, with a recovery rate limited to 75%. A large amount of water is discharged with the concentrate, contradicting the goals of energy conservation, emission reduction, and efficient resource utilization, and failing to meet current environmental protection and sustainable development requirements. Summary of the Invention

[0005] To address the aforementioned technical problems of low treatment efficiency, significant resource waste, and insufficient concentration in existing technologies, this invention provides a biomass-based methanol production wastewater treatment system. This invention primarily utilizes heat pump evaporation and gas separation membranes to separate organic solvents, salts, and ethanol. The ethanol is recycled as a carbon source. Combined with dual-alkali methods, multi-media filtration, ultrafiltration, reverse osmosis, and ion exchange resins for deep wastewater treatment, this system effectively solves the problems of high COD and poor biodegradability in wastewater, optimizes biochemical treatment efficiency, achieves resource recovery and deep emission reduction, and ensures that the effluent meets discharge standards.

[0006] The technical means employed in this invention are as follows: A biomass-to-methanol wastewater treatment system includes a polyimide monomer wastewater pretreatment system, a biochemical treatment system, and a membrane system; The polyimide monomer wastewater pretreatment system includes a wastewater collection tank, a low-temperature evaporation device, an ethanol collection tank, and a concentrated water collection tank. The inlet of the wastewater collection tank is connected to the polyimide monomer wastewater discharge pipe, the outlet of the wastewater collection tank is connected to the inlet of the low-temperature evaporation device, the first outlet of the low-temperature evaporation device is connected to the concentrated water collection tank, the second outlet of the low-temperature evaporation device is connected to the ethanol collection tank, and the outlet of the ethanol collection tank is connected to the homogenization tank. The biochemical treatment system includes a coagulation sedimentation tank, a homogenization tank, an anoxic-aerobic tank, a secondary sedimentation tank, a coagulation flotation machine, an aerated biological filter, a combined water tank, a softening sedimentation tank, an intermediate water tank, a multi-media filter, and a multi-media filter product water tank. The inlet of the coagulation sedimentation tank is connected to the black and gray water discharge pipe, and the outlet of the coagulation sedimentation tank is sequentially connected to the homogenization tank, the anoxic-aerobic tank, the secondary sedimentation tank, the coagulation flotation machine, the aerated biological filter, the combined water tank, the softening sedimentation tank, the intermediate water tank, the multi-media filter, and the multi-media filter product water tank.

[0007] Furthermore, the membrane system includes an ultrafiltration system, an ultrafiltration permeate tank, a reverse osmosis system, and a reclaimed water tank; The inlet of the ultrafiltration system is connected to the outlet of the multi-media filter permeate tank. The outlet of the ultrafiltration system is sequentially connected to the ultrafiltration permeate tank and the reverse osmosis system. The desalination outlet of the reverse osmosis system is connected to the inlet of the reclaimed water tank. The concentrate outlet of the reverse osmosis system is sequentially connected to the first concentrate tank, the ion exchange system, the desalination tank, and the concentrate reverse osmosis system. The desalination outlet of the concentrate reverse osmosis system is connected to the inlet of the reclaimed water tank. The concentrate outlet of the concentrate reverse osmosis system is connected to the inlet of the second concentrate tank.

[0008] Furthermore, the temperature range inside the low-temperature evaporation device is 30~40℃, and the pressure inside the low-temperature evaporation device is low.

[0009] Furthermore, a pervaporation membrane is provided between the second outlet of the low-temperature evaporation device and the ethanol collection tank.

[0010] Furthermore, domestic sewage and initial rainwater enter the equalization tank after passing through the screen.

[0011] Furthermore, the inlet of the integrated water tank is also connected to a circulating sewage pipe.

[0012] Furthermore, the screenings from the grid, the sludge from the coagulation sedimentation tank and the softening sedimentation tank, and the scum from the coagulation flotation machine enter the sludge tank.

[0013] Compared with the prior art, the present invention has the following advantages: This invention combines the application of heat pump evaporation and gas separation membrane to separate organic solvents and salts from water and ethanol in PI monomer wastewater; it solves the problems of high COD content, large amounts of organic solvents and salts, and extremely poor biodegradability of PI monomer wastewater; and at the same time, it realizes the resource recovery of ethanol.

[0014] Suspended solids in black and gray water are treated by coagulation and sedimentation, and then enter the biological system for carbon and nitrogen removal. The ammonia nitrogen content in the water is relatively high, and the C:N=2, so an additional carbon source is needed. Ethanol produced by PI monomer pretreatment is used as a carbon source to achieve resource utilization. In this invention, the biochemical effluent and circulating wastewater are mixed, and hardness is removed by a dual-alkali method. Then, the effluent enters a multi-media filter, ultrafiltration, and reverse osmosis system. To improve the recovery rate, the concentrated water enters an ion exchange resin. After the hardness is reduced, the concentrated water enters a concentrated water reverse osmosis system. The overall recovery rate of the system is improved, the concentrated water concentration factor is increased, and the effluent meets the requirements for pipe connection and can be directly discharged. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the system structure of the present invention. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0020] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0021] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0022] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0023] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0024] like Figure 1 As shown, the present invention provides a biomass-to-methanol wastewater treatment system, including a polyimide monomer wastewater pretreatment system, a biochemical treatment system, and a membrane system; The polyimide monomer wastewater pretreatment system includes a wastewater collection tank, a low-temperature evaporator, an ethanol collection tank, and a concentrated water collection tank. The inlet of the wastewater collection tank is connected to the polyimide monomer wastewater discharge pipe, and the outlet of the wastewater collection tank is connected to the inlet of the low-temperature evaporator. The first outlet of the low-temperature evaporator is connected to the concentrated water collection tank, and the second outlet of the low-temperature evaporator is connected to the ethanol collection tank. A pervaporation membrane is installed between the second outlet of the low-temperature evaporator and the ethanol collection tank. The outlet of the ethanol collection tank is connected to a homogenization tank. Preferably, the low-temperature evaporation device can be an air-source heat pump low-temperature vacuum evaporation and concentration system. A multi-media filter, used as pretreatment filtration before the membrane treatment system, is generally composed of garnet, quartz sand, and anthracite arranged in layers. The ion exchange system can be a sodium ion exchange system.

[0025] The biochemical treatment system includes a coagulation sedimentation tank, a homogenization tank, an anoxic-aerobic tank, a secondary sedimentation tank, a coagulation-flotation unit, an aerated biological filter, a combined water tank, a softening sedimentation tank, an intermediate water tank, a multi-media filter, and a multi-media filter product water tank. The inlet of the coagulation sedimentation tank is connected to the black and grey water discharge pipe, and the outlet of the coagulation sedimentation tank is sequentially connected to the homogenization tank, the anoxic-aerobic tank, the secondary sedimentation tank, the coagulation-flotation unit, the aerated biological filter, the combined water tank, the softening sedimentation tank, the intermediate water tank, the multi-media filter, and the multi-media filter product water tank. Domestic sewage and initial rainwater enter the homogenization tank after passing through a screen. The inlet of the combined water tank is also connected to a circulating sewage discharge pipe.

[0026] The membrane system includes an ultrafiltration system, an ultrafiltration permeate tank, a reverse osmosis system, and a reclaimed water tank; The inlet of the ultrafiltration system is connected to the outlet of the multi-media filter permeate tank. The outlet of the ultrafiltration system is sequentially connected to the ultrafiltration permeate tank and the reverse osmosis system. The desalination outlet of the reverse osmosis system is connected to the inlet of the reclaimed water tank. The concentrate outlet of the reverse osmosis system is sequentially connected to the first concentrate tank, the ion exchange system, the desalination tank, and the concentrate reverse osmosis system. The desalination outlet of the concentrate reverse osmosis system is connected to the inlet of the reclaimed water tank. The concentrate outlet of the concentrate reverse osmosis system is connected to the inlet of the second concentrate tank.

[0027] This invention presents a complete process chain, using clean water as makeup water for the intercooled circulating cooling system, while concentrated wastewater is discharged into the park's wastewater treatment plant. This maximizes water utilization while meeting reuse standards, achieving the goals of water conservation and emission reduction. The system includes a polyimide monomer wastewater pretreatment system, a biochemical treatment system, and a membrane treatment system.

[0028] Polyimide monomer wastewater pretreatment system: Polyimide monomer wastewater is a high-concentration organic wastewater with high salt, high COD, and high biotoxicity. The COD reaches hundreds of thousands and contains organic solvents such as DMF (N,N-dimethylformamide), DMAC (N,N-dimethylacetamide), and p-chloronitrobenzene; salt content is 2-3%; ethanol, etc. It must be pretreated before entering the biological system. Given the relatively small volume of PI monomer wastewater and the significant difference in boiling points between ethanol and DMF (N,N-dimethylformamide), DMAC (N,N-dimethylacetamide), and p-chloronitrobenzene, a low-temperature evaporation technology is employed for concentration. Operating at 30-40℃ and under low pressure, ethanol and water can be recovered as condensate, while DMF, DMAC, p-chloronitrobenzene, and salts remain in the concentrated liquid. The wastewater concentration is approximately 8-10 times. The concentrated liquid is disposed of as hazardous waste through an external disposal agency. The condensate is used to separate ethanol and water through a pervaporation membrane, achieving ethanol concentration and purification. Low pressure is defined as a working vacuum level within -0.093 to -0.098 MPa.

[0029] Biological treatment system: The black and grey water contains a large amount of suspended solids, with COD of 200 mg / L and ammonia nitrogen of 100 mg / L. The ammonia nitrogen content is relatively high, requiring the addition of a carbon source. The condensate from the low-temperature evaporation of the PI monomer wastewater can be used as the carbon source. The black and grey water first undergoes coagulation and sedimentation to remove suspended solids, biotoxic sulfides, and cyanides. The effluent then enters an anoxic tank, an aerobic tank, a secondary sedimentation tank, a coagulation-flotation system, and an aerated biological filter. The effluent COD is less than 40 mg / L, and the ammonia nitrogen is 5 mg / L.

[0030] Membrane system: The biochemical effluent, circulating wastewater, and desalination station wastewater are mixed and treated with a dual-alkali method to remove hardness before entering a multi-media filter. Then, it enters the membrane system, which undergoes ultrafiltration, reverse osmosis, ion exchange resin, and concentrated water reverse osmosis. The effluent is used as makeup water for the circulating cooling water. The concentrated water meets the standards for pipe connection and is directly discharged into the park's wastewater treatment plant.

[0031] The workflow of this invention is as follows: PI monomer wastewater is first collected and enters a wastewater collection tank. After being pumped, it enters a low-temperature evaporation device, which operates under slight negative pressure, maintaining a temperature of 30-40℃. The condensate from the vapor enters a pervaporation membrane for ethanol concentration and purification, then enters a collection tank. The concentrated water enters a concentrated water collection tank, awaiting outsourced treatment. Domestic sewage and initial rainwater pass through a screen and enter a homogenization tank. Black and grey water undergoes coagulation and sedimentation to remove most suspended solids and colloids, then enters the homogenization tank for homogenization and equalization with the PI condensate, domestic sewage, and initial rainwater. It then enters a pre-anaerobic / aerobic tank – secondary sedimentation tank – coagulation and flotation machine to remove suspended solids. After flotation and colloid removal, the water enters the aerated biological filter. The effluent flows into the integrated water tank and is then incorporated into the circulating wastewater system. From there, it enters the softening sedimentation tank-intermediate water tank, where it is pumped into a multi-media filter for further removal of suspended solids and colloids. After this, it enters the membrane treatment system, ultrafiltration system-reverse osmosis system. Freshwater enters the reclaimed water tank, while concentrated water undergoes ion exchange to remove hardness and enters the concentrated water reverse osmosis system. The concentrated water from the reverse osmosis enters the concentrated water tank, and after passing testing, it is discharged into the sewage network and into the park's wastewater treatment plant. Freshwater enters the reclaimed water tank to improve water recovery rate. Screenings, sedimentation tank sludge, and flotation machine scum enter the sludge tank, are dewatered by a plate and frame filter press, and are then outsourced for further treatment.

[0032] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A biomass-to-methanol wastewater treatment system, characterized in that: This includes a polyimide monomer wastewater pretreatment system, a biochemical treatment system, and a membrane system; The polyimide monomer wastewater pretreatment system includes a wastewater collection tank, a low-temperature evaporation device, an ethanol collection tank, and a concentrated water collection tank. The inlet of the wastewater collection tank is connected to the polyimide monomer wastewater discharge pipe, the outlet of the wastewater collection tank is connected to the inlet of the low-temperature evaporation device, the first outlet of the low-temperature evaporation device is connected to the concentrated water collection tank, the second outlet of the low-temperature evaporation device is connected to the ethanol collection tank, and the outlet of the ethanol collection tank is connected to the homogenization tank. The biochemical treatment system includes a coagulation sedimentation tank, a homogenization tank, an anoxic-aerobic tank, a secondary sedimentation tank, a coagulation flotation machine, an aerated biological filter, a combined water tank, a softening sedimentation tank, an intermediate water tank, a multi-media filter, and a multi-media filter product water tank. The inlet of the coagulation sedimentation tank is connected to the black and gray water discharge pipe, and the outlet of the coagulation sedimentation tank is sequentially connected to the homogenization tank, the anoxic-aerobic tank, the secondary sedimentation tank, the coagulation flotation machine, the aerated biological filter, the combined water tank, the softening sedimentation tank, the intermediate water tank, the multi-media filter, and the multi-media filter product water tank.

2. The biomass-to-methanol wastewater treatment system according to claim 1, characterized in that, The membrane system includes an ultrafiltration system, an ultrafiltration permeate tank, a reverse osmosis system, and a reclaimed water tank; The inlet of the ultrafiltration system is connected to the outlet of the multi-media filter permeate tank. The outlet of the ultrafiltration system is sequentially connected to the ultrafiltration permeate tank and the reverse osmosis system. The desalination outlet of the reverse osmosis system is connected to the inlet of the reclaimed water tank. The concentrate outlet of the reverse osmosis system is sequentially connected to the first concentrate tank, the ion exchange system, the desalination tank, and the concentrate reverse osmosis system. The desalination outlet of the concentrate reverse osmosis system is connected to the inlet of the reclaimed water tank. The concentrate outlet of the concentrate reverse osmosis system is connected to the inlet of the second concentrate tank.

3. The biomass-to-methanol wastewater treatment system according to claim 1, characterized in that, The temperature range inside the low-temperature evaporation device is 30~40℃, and the pressure inside the low-temperature evaporation device is low.

4. The biomass-to-methanol wastewater treatment system according to claim 1, characterized in that, A pervaporation membrane is provided between the second outlet of the low-temperature evaporation device and the ethanol collection tank.

5. The biomass-to-methanol wastewater treatment system according to claim 1, characterized in that, Domestic sewage and initial rainwater enter the equalization tank after passing through the screen.

6. The biomass-to-methanol wastewater treatment system according to claim 1, characterized in that, The inlet of the integrated water tank is also connected to the circulating sewage pipe.

7. The biomass-to-methanol wastewater treatment system according to claim 5, characterized in that, The sludge from the bar screen, the sludge from the coagulation sedimentation tank and the softening sedimentation tank, and the scum from the coagulation flotation machine enter the sludge tank.

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