Water treatment system

Abstract

Various embodiments of the present application relate to a water treatment system. The water treatment system includes a manufacturing tool that produces wastewater, a strong acid cation unit, and at least one activated carbon filter unit. The strong acid cation unit receives the wastewater and includes an ion exchange bed for treating the wastewater into an acidic wastewater stream. The at least one activated carbon filter unit is downstream of the strong acid cation unit and includes at least one activated carbon compacted bed stage for adsorbing perfluoroalkyl substances present in the acidic wastewater stream. The wastewater stream exiting the activated carbon filter unit can be reused, recycled, or discharged without polluting emissions.

Description

Technical Field

[0001] This utility model relates to a water treatment system. Background Technology

[0002] Integrated circuits are formed on semiconductor chips. The photolithography patterning process uses ultraviolet light to transfer the desired photomask pattern onto a photoresist layer on the semiconductor chip. An etching process is then used to transfer the pattern to a layer beneath the photoresist. This process is repeated multiple times using different patterns to create different layers on the chip substrate and fabricate useful devices. Water is used in several steps, generating wastewater that requires treatment. Utility Model Content

[0003] Some embodiments disclosed herein pertain to a water treatment system comprising a wastewater production apparatus, a strong acid cation exchange unit, and at least one activated carbon filter unit. The strong acid cation exchange unit receives the wastewater and includes an ion exchange layer for treating the wastewater into an acidic wastewater stream. The at least one activated carbon filter unit is located downstream of the strong acid cation exchange unit and includes at least one activated carbon compacted bed stage for adsorbing perfluoroalkyl substances present in the acidic wastewater stream. Attached Figure Description

[0004] When with attachment Figure 1 The best understanding of all aspects of this disclosure can be obtained from the detailed description below. It should be noted that, in accordance with industry standard practice, the various features are not drawn to scale. In fact, for clarity, the dimensions of the various features may be increased or decreased arbitrarily.

[0005] Figure 1 This is a schematic diagram of one embodiment of a water treatment system based on some embodiments of the present disclosure.

[0006] Figure 2 This is a schematic diagram of a strong acid cation (SAC) unit.

[0007] Figure 3 This is a schematic diagram of an activated carbon filter (ACF) unit.

[0008] Figure 4 This is a schematic diagram of another embodiment of a water treatment system based on some embodiments of the present disclosure. This embodiment includes a SAC unit and a plurality of ACF units, which are arranged in parallel and series with each other.

[0009] Figure 5 These are schematic diagrams based on some embodiments of the present disclosure, illustrating the flow of water through a semiconductor manufacturing process.

[0010] Figure 6A , Figure 6B and Figure 6C The diagram illustrates semiconductor manufacturing steps in a manufacturing tool using perfluoroalkyl substances (PFAS) and / or tetramethylammonium hydroxide (TMAH), according to some embodiments.

[0011] Figure 7 This is a flowchart illustrating, according to certain embodiments, a method for recovering wastewater from a semiconductor or display panel manufacturing process, or more broadly, a method for removing perfluoroalkyl substances (PFAS) from an initial fluid stream.

[0012] Figure 8 This is a schematic diagram of a water treatment system for producing ultrapure water for semiconductor manufacturing, based on some embodiments.

[0013] Figure 9 The present invention illustrates, according to some embodiments, a flowchart of a method for producing ultrapure water for the manufacture of semiconductors or display panels.

[0014] Figure 10 It is a graph showing the zeta potential of three different types of activated carbon versus pH. Detailed Implementation

[0015] The following disclosure provides numerous different embodiments or examples for implementing various features of the provided subject matter. Specific examples of components and configurations are described below to simplify this disclosure. Of course, these are merely examples and are not intended to be limiting. For example, in the following description, the formation of a first feature over or on a second feature may include embodiments where the first and second features are formed in direct contact, and may also include embodiments where additional features are formed between the first and second features such that the first and second features are not in direct contact. Furthermore, reference numerals and / or letters may be repeated in various instances in this disclosure. This repetition is for simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed.

[0016] Furthermore, for ease of explanation, this document uses spatially relative terms such as "beneath," "below," "lower," "above," and "upper" to describe the relationship between one component or feature shown in the figures and another component or feature. These spatially relative terms are intended to cover different orientations of the device in use or operation, in addition to those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein can be interpreted accordingly.

[0017] The numerical values ​​in this specification and the claims of this application should be understood to include the same numerical values ​​when reduced to the same significant figures, as well as numerical values ​​whose difference from the stated values ​​is less than the experimental error of the conventional measurement techniques described in this application. All scopes disclosed herein include the endpoints described.

[0018] The term "about" can be used to include any numerical value that can vary without altering the underlying functionality of the value. When used with a range, "about" also reveals a range defined by the absolute values ​​of its two endpoints; for example, "about 2 to about 4" also reveals a range "from 2 to 4". The term "about" can refer to ±10% of the stated numerical value.

[0019] The terms "inlet" and "outlet" are relative to a given structure through which fluid flows; for example, fluid flows into the structure through an inlet and out through an outlet. The terms "upstream" and "downstream" are also relative to the direction of fluid flow through various components; that is, fluid flows through an upstream component before flowing through a downstream component. It should be noted that when a loop exists, the first component can be described as being both upstream and downstream of the second component.

[0020] The term "fluidly connected" refers to two components connected in such a way that fluid in one component will eventually reach the second component. This term allows for the presence of other structures and components between two fluidly connected components.

[0021] The term "directly" is used to indicate that the fluid in the first component then flows into the second component without affecting the composition of the fluid in any other component.

[0022] As used herein, the term "wastewater" refers to water that has been used in the manufacturing process and therefore includes byproducts of these processes. The term "tap water" or "feed water" refers to influent water that has been treated to drinking water standards and has a conductivity of approximately 200 to approximately 300 microsiemens per centimeter (µS / cm). The term "ultrapure water" or "UPW" refers to water with very low levels of contaminants such as particles and ions, having a conductivity of less than 1 (µS / cm) or a resistivity of 18.0 to 18.25 Mohm-cm.

[0023] Water is used in many aspects of semiconductor manufacturing, such as cleaning or rinsing chips to remove debris between individual manufacturing steps (surface conditioning, stripping, wet etching, solvent treatment, chemical mechanical planarization (CMP)). The resulting wastewater contains several different types of contaminants, including acids such as sulfuric acid or hydrofluoric acid; polymers; silicates; hydrogen peroxide, slurry particles, metals such as copper or iron; and inorganic ions. These contaminants need to be removed before the water can be reused, redirected, or disposed of. For some background information, a single manufacturing plant may use 2 million to 5 million gallons (7,500 to 19,000 cubic meters) of water per day.

[0024] This disclosure relates to systems and methods for removing perfluoroalkyl substances (PFAS) from wastewater, particularly wastewater generated during semiconductor or display panel manufacturing processes, or from tap water. PFAS are compounds having a number of fluorine atoms along an alkyl chain (e.g., ranging from C3 to C12). Some non-limiting examples include perfluorooctanesulfonic acid (PFOS), perfluorooctanoic acid (PFOA), fluoroalkyl sulfonamides, fluorinated polymers, and fluorinated sulfonamide alcohols. PFAS are used in manufacturing processes, for example, to reduce surface tension or improve the resolution of lithographic patterns and reduce pattern collapse. They are used in lubricants, photoresists, wet etching formulations, etching chamber gases, solvents, developers, rinsing solutions, or as materials in equipment such as tanks, valves, pumps, and pipes. However, PFAS also have effects on reproduction and development. Therefore, government regulations limit the amount of PFAS emissions that may occur.

[0025] The disclosed system includes the use of a strong acid cation exchange (SAC) unit or tank, through which the treated fluid is passed directly or fed into an activated carbon filter (ACF) unit or tank. The ACF unit uses activated carbon derived from bituminous coal. This almost completely adsorbs PFAS contaminants, particularly short-chain C3–C7 PFAS. No backwashing step is required, no chemicals are added, and no pollution emissions are generated. Furthermore, tetramethylammonium hydroxide (TMAH), commonly used as a developer or solvent in semiconductor or display panel manufacturing, is also captured by the system. The resulting treated water is used as secondary water in various applications.

[0026] Figure 1 This is a schematic diagram of one embodiment of a water treatment system 100 for treating wastewater generated in the manufacture of semiconductors or display panels, based on some embodiments. The system includes a strong acid cation exchange (SAC) unit 130, which is located directly upstream of an activated carbon filter (ACF) unit 140. In other words, the ACF unit is located directly downstream of the SAC unit.

[0027] The figure also shows a buffer tank 120, located downstream of the feed line of wastewater flow 110. The buffer tank serves to buffer downstream system components from sudden surges in fluid flow into the water treatment system. This occurs, for example, when water is used in different manufacturing steps and then fed into the water treatment system.

[0028] The wastewater stream is generated during semiconductor manufacturing or display panel manufacturing. In certain embodiments, the wastewater stream contains perfluoroalkyl substances (PFAS), which are used in various manufacturing steps of semiconductor or display panel production. In other specific embodiments, the wastewater stream also contains tetramethylammonium hydroxide (TMAH), which is commonly used as a developer or solvent. Other contaminants are also present in the wastewater stream.

[0029] Filter 122 is located downstream of buffer tank 120 and upstream of SAC unit 130. Filter 122 is, for example, a fibrous matrix formed of polymer fibers. In a particular embodiment, the polymer is polypropylene, polyethersulfone, cellulose acetate, nylon, polyester, polyamide, polyethylene, polytetrafluoroethylene, polysulfone, or polyimide. Homopolymers and copolymers of these polymers may also be used if desired. In a particular embodiment, the average diameter of the fibers in the fibrous matrix is ​​from about 0.1 micrometers (µm) to about 10 µm. This can be measured using conventional methods. However, other ranges and values ​​are also considered and are within the scope of this disclosure. The filter has high permeability and high ion absorption, enabling it to effectively control the concentration of various ions in the wastewater stream. The filter also effectively captures suspended solids present in the wastewater stream.

[0030] like Figure 1 As shown, the pH value of the wastewater stream 112 entering SAC unit 130 is typically alkaline; in other words, its pH value is between 7 and 14. (Refer to...) Figure 2 This is a schematic diagram of an SAC unit 130, with a housing or tank 132 receiving an influent stream 131, shown here entering from the top of the tank. The tank 132 includes an ion exchange layer 136 where various cations in the wastewater stream are captured. These cations include tetramethylammonium ions of TMAH, other quaternary ammonium ions, and other metal cations that may be present, such as calcium, magnesium, iron, or sodium. These cations exchange with hydrogen ions. The ion exchange layer is, for example, an ion exchange resin provided in bead form and packaged in a bed or column. This ion exchange resin is, for example, made of cross-linked polystyrene containing sulfonic acid groups. A top space 134 exists above the ion exchange layer within the tank. After the influent stream passes through the ion exchange layer under pressure, an outfluent stream 139 flows out from the bottom of the tank.

[0031] like Figure 1 As shown, the pH of wastewater stream 114 exiting SAC unit 130 and entering ACF unit 140 is no longer alkaline but acidic; in other words, its pH ranges from 7 to 1. In a more specific embodiment, the pH of the acidic wastewater stream entering ACF unit 140 is 5 or lower, i.e., from 5 to 1. The TMAH concentration of wastewater stream 114 is also significantly reduced, for example, by more than 90%, including more than 95%, including more than 99%, or more than 99.9%, or more than 99.99%, compared to the TMAH concentration in the initial wastewater stream. Other ranges and values ​​are also considered and are within the scope of this disclosure.

[0032] Now refer to Figure 3 This is a schematic diagram of the ACF unit 140. Similarly, the housing or tank 142 receives the feed stream 141, shown here as entering from the top of the tank. As shown here, the tank contains two bed stages 146, 148, containing compacted activated carbon particles. However, any number of bed stages can exist, including one or more stages, depending on the requirements. Wastewater flows through one or more bed stages. The activated carbon particles adsorb PFAS present in the wastewater and remove them from the wastewater stream. In particular, short-chain PFAS (C3-C7) are adsorbed at a high rate. A top space 144 exists within the tank above the bed stages. After the feed stream passes under pressure through the activated carbon, the output stream 149 flows out from the bottom of the tank. The PFAS concentration in the outflowing output stream is significantly lower than that of the incoming feed stream. In some embodiments, the PFAS concentration in the output stream of the ACF unit is reduced by more than 95%, including more than 99%, including more than 99.9%, or more than 99.99%, or more than 99.999%, compared to the PFAS concentration in the feed stream. Furthermore, as shown herein, the pH of the outflowing output stream remains acidic.

[0033] The activated carbon particles used in the ACF unit are derived from coal. In a more specific embodiment, the activated carbon particles are derived from bituminous coal. These activated carbon particles contain micropores with a diameter of less than 2 nanometers. Notably, at acidic pH, the activated carbon derived from coal is positively charged, while the activated carbon derived from coconut shells is negatively charged at acidic pH. Activated carbon can be provided as powdered, granular, or pelletized activated carbon as needed.

[0034] like Figure 1 As shown, the pH of wastewater stream 116 exiting ACF unit 140 remains acidic. The PFAS concentration of this wastewater stream 116 is reduced by more than 95%, including more than 99%, including more than 99.9%, or more than 99.99%, or more than 99.999%, compared to the initial wastewater stream 110. In some specific embodiments, the PFAS concentration in this effluent wastewater stream 116 is 10 parts per trillion (10 ppt) or less. The TMAH concentration of this wastewater stream 116 is also reduced by more than 90%, including more than 99%, compared to the initial wastewater stream 110. The effluent wastewater stream 116 can then be reused, recycled, or discharged. For example, the effluent wastewater stream can be used for secondary water applications, such as water for cooling towers or local scrubbers.

[0035] Now refer to Figure 4In some specific embodiments, the wastewater flow passes through the SAC unit 130 at a linear velocity of about 10 m / hr to about 20 m / hr, including from about 12 m / hr to about 16 m / hr. Similarly, the wastewater flow passes through the ACF unit 140 at a linear velocity of about 3 m / hr to about 8 m / hr, including from about 4 m / hr to about 6 m / hr. In other specific embodiments, the ratio of the linear velocity through the SAC unit to the linear velocity through the ACF unit ranges from about 2:1 to about 4:1, including about 3:1. Other ranges and values ​​are also considered and are within the scope of this disclosure. Due to the lower linear velocity through the ACF unit, it is considered that multiple (or more) ACF units exist in the system and are arranged in parallel with each other. Figure 4 An example of such a system is shown. Here, the acidic wastewater stream 114 exiting a SAC unit 130 is split into multiple parallel streams, each passing through at least one ACF unit. Three distinct streams are shown here, each passing sequentially through one or two ACF units 140 / 154, 150 / 156, and 152 / 158. The wastewater streams exiting the ACF units are then recombined. Here, a second buffer tank 124 is located after the SAC unit and upstream of the ACF units, and a recovery tank 160 is shown in the figure, in which the PFAS-free wastewater streams from the ACF units are combined for recovery and / or further downstream treatment. Using multiple ACF units also allows for servicing of individual ACF units without shutting down the entire process. Each ACF unit includes, for example, a tensiometer to measure surface tension and help determine if the ACF unit is saturated.

[0036] Figure 5A schematic diagram of some parts of the water movement during semiconductor manufacturing is shown. A chemical transfer unit (CTU) 200 is used to transfer one or more chemicals to one or more mixing tanks 210 along fluid path 212. A waste liquid path 214 is also shown, extending from CTU 200 to a collection pit 220, where waste liquid is collected and combined. Non-limiting examples of chemicals transferred and mixed include deionized water (DIW), ultrapure water (UPW), surfactants, ammonia, or other additives. Fluid is transferred from mixing tank 210 to chemical mixing system (CMU) 230, where the fluid is mixed again to improve consistency and reduce variations that occur in mixing tank 210. CMU 230 delivers its fluid output along fluid path 216 to metering tank 240, where the fluid is stored for final use. Chemical dispense system (CDU) 250 controls the fluid flow along fluid path 252 from metering tank 240 to the desired manufacturing tool 260. Wastewater path 254 extends from CDU 250 to sump 220. Other chemicals, such as TMAH, are also supplied directly to the required manufacturing tools 260.

[0037] Manufacturing tool 260 generates a wastewater flow 262 that is fed into buffer tank 120. Sump 220 also transfers the wastewater flow 222 to buffer tank 120.

[0038] A buffer tank serves as the feed source for a water treatment system 100, which includes a SAC unit 130 and an ACF unit 140 as previously described. The treated wastewater exiting the ACF unit, containing significantly reduced PFAS and / or TMAH levels / concentrations, is collected in a wastewater tank 270 for further downstream treatment. A separate tool 280 is also shown in the figure, which feeds into a separate wastewater treatment system 290 and then into the wastewater tank 270. This may occur, for example, for tools that do not produce PFAS-containing wastewater streams.

[0039] Figures 6A-6C This is a side cross-sectional view showing how a tool or process in the manufacture of a semiconductor or display panel uses TMAH and / or PFAS. Figure 6A In this process, a metal layer 310 exists on a substrate 300. A photoresist layer 320 on the metal layer has been applied, patterned, and developed.

[0040] For semiconductor devices, substrate 300 may be a chip made of semiconductor materials, such as silicon, for example, in the form of crystalline silicon. In alternative embodiments, the substrate may be made of other elemental semiconductors (such as germanium), or may include compound semiconductors (such as silicon carbide (SiC), gallium arsenide (GaAs), gallium carbide, gallium phosphide, indium arsenide (InAs), indium phosphide (InP), silicon germanium, silicon germanium carbide, gallium arsenide phosphide, or indium gallium phosphide). For display panels, substrate 300 may be glass.

[0041] Typically, photoresist layers are applied by methods such as spin coating, spray coating, roller coating, dip coating, or extrusion coating. Generally, in spin coating, the substrate is placed on a rotating platform that includes a vacuum fixture to hold the substrate in place. The photoresist composition is then applied to the center of the substrate. The speed of the rotating platform is then increased to allow the photoresist to spread uniformly from the center of the substrate to its periphery. The rotational speed of the platform is then fixed, which controls the final thickness of the photoresist layer.

[0042] Next, the photoresist composition is baked or cured to remove the solvent and harden the photoresist layer. In some specific embodiments, baking is performed at a temperature of about 90 degrees Celsius to about 110 degrees Celsius. Baking can be performed using a hot plate or oven, or similar equipment. In this way, a photoresist layer is formed on the substrate.

[0043] The photoresist layer is then patterned by exposure to radiation. The radiation is any wavelength of light carrying the desired shielding pattern. In a particular embodiment, EUV light with a wavelength of about 13.5 nm is used for patterning because this allows for smaller feature sizes. This results in some portions of the photoresist layer being exposed to radiation, while other portions are not. This exposure makes some portions of the photoresist soluble in the developer, while other portions remain insoluble.

[0044] An additional photoresist baking step (post-exposure bake, PEB) is performed after exposure to radiation. For example, this helps to release acid leaving groups (ALGs) or other molecules that are important in chemically amplified photoresists.

[0045] The photoresist layer is then developed using a developer. The developer can be an aqueous solution or an organic solvent. The soluble portions of the photoresist layer dissolve and are washed away during the development step, leaving the photoresist pattern (i.e., the mask). A common example of a developer is water-soluble tetramethylammonium hydroxide (TMAH). Figure 6A The resulting structure is shown.

[0046] The metal layer is then etched, for example using dry etching or wet etching. (See reference...) Figure 6BTrench 315 exists in the metal layer. Figure 6C In the process, the photoresist layer is then removed, for example, using a rinsing solution. This is accomplished, for example, using various solvents such as N-methyl-pyrrolidone (NMP) or alkaline media or other stripping agents at high temperatures, or by dry etching using oxygen plasma.

[0047] In these process steps, PFAS are present in the photoresist or in the etching formulation. TMAH is used as a developer for photoresist patterning and also in the rinsing solution. Therefore, refer to... Figure 5 PFAS and TMAH are present in any wastewater stream leaving this type of manufacturing tool 260.

[0048] Figure 7 A flowchart illustrating some embodiments is provided, showing a method 400 for recovering wastewater from a semiconductor or display panel manufacturing process, or more broadly, removing perfluoroalkyl substances (PFAS) from an initial wastewater stream. This method generally involves... Figure 1 As shown below. Although the methods and steps discussed below refer only to certain components of a water treatment system, this discussion should also be broadly understood to allow for the presence of other components.

[0049] Reference Figure 1 The initial wastewater stream 110, for example, originates from semiconductor manufacturing or display panel manufacturing. Figure 7 In optional step 405, the initial wastewater stream 110 passes through filter 122. For example, the filter is used to capture large particles present in the initial wastewater stream. Next, in Figure 7 In step 410, the wastewater stream passes through and is treated in the strong acid cation exchange (SAC) unit 130. The resulting output can be referred to as acidic wastewater stream 114. As previously described, the TMAH content of the acidic wastewater stream is reduced, and it has an acidic pH value. Then, in Figure 7 In step 415, the acidic wastewater stream then passes through and is treated in the activated carbon filter (ACF) unit 140 to remove PFAS.

[0050] It is also considered to use the combination of SAC unit 130 and ACF unit 140 to remove PFAS from tap water entering semiconductor or display panel manufacturing facilities. Figure 8 This is a schematic diagram of water treatment system 102, which is used to produce ultrapure water (UPW) for use in the facility. The system includes SAC and ACF units, as well as other units or components for performing different types of treatment on the water to obtain the desired ultrapure water. Figure 9 The following is a flowchart illustrating a method 500 for producing ultrapure water, based on some embodiments. These two figures will be discussed together.

[0051] In very general terms, other units or components of a water treatment system include one or more of the following: a multi-media filter (MMF) 430, a 2-bed 3-tower (2B3T) unit 435, a reverse osmosis (RO) unit 440, an ultraviolet (UV) unit 445, a stratified bed polisher (SBP) unit 450, a membrane degassing (MDG) unit 455, a second ultraviolet (UV) unit 457, a cautionary polish (CP) unit 460, a second membrane degassing (MDG) unit 462, and an ultrafiltration (UF) unit 465. Additional tanks, filters, heat exchangers, piping, valves, gauges, sensors, etc., which are also typically present, are not listed here.

[0052] Tap water typically has a total organic carbon (TOC) content greater than 0.1 ppm to a maximum of 1.0 ppm. For comparison purposes, final ultrapure water (UPW) produced at the end of a water treatment system and supplied at the point of use requires a TOC content of less than 1.0 ppb (parts per billion), or even more ideally less than 0.5 ppb or less than 0.3 ppb. UPW also has a resistivity of 18.0 to 18.25 Mohm-cm and a dissolved oxygen content of less than 10 ppb.

[0053] Continue, in Figure 9 In step 505, the initial fluid flow 110 enters the MMF 430. This is a filter typically formed by at least three layers of different media, stratified by size and density. Larger and less dense particles are arranged at the top, while smaller and denser particles are arranged at the bottom. Common media include anthracite (less dense), sand, and garnet (densest), with a gravel support layer at the bottom. The media form a bed within the tank. Water is fed into the top of the tank and, driven by pressure, flows laminarly to the bottom, where the treated water exits. Stratification causes larger contaminants to be captured near the top and smaller contaminants near the bottom, thus utilizing the entire bed depth for filtration.

[0054] MMF is used to reduce the amount of suspended solids (turbidity) in water flow. These solids include, for example, small stones, soil / silt, organic matter, and plants / microorganisms. MMF removes large particles ranging from approximately 10 micrometers (µm) to approximately 25 µm in average diameter.

[0055] Next, in Figure 9In step 510, the fluid flow is processed in SAC unit 130. Figure 9 In step 515, the fluid flow is processed in ACF unit 140. The functions of these two units have been previously described. As a result, PFAS and other ions, chlorine, organic molecules, and other oxidants present in the water flow are removed.

[0056] exist Figure 9 In step 520, the fluid stream exiting the SAC / ACF combination is subsequently treated in unit 435 (2B3T). This is used to remove other cations and anions, or in other words, to remove minerals from the water stream and improve water quality. Typically, this unit includes a cation exchange tower containing a bed of cation exchange resin for removing cations from the water stream. The output stream of the cation exchange tower is used as the feed stream to a decarbonation tower (DC) or degasifier (DG), where carbon dioxide is removed from the water stream. Inside the decarbonation tower, the water stream is broken into multiple small droplets. An airflow blows through these droplets, transferring gas from the droplets into the airflow. The decarbonized / degassed droplets are collected at the bottom of the tower. The output stream of the decarbonation tower is used as the feed stream to an anion exchanger tower (AEX). The anion exchange tower includes a bed of anion exchange resin for removing anions from the water stream. The output stream of the anion exchanger tower continues to subsequent downstream treatment units.

[0057] exist Figure 9 In step 525, the fluid flow is processed in RO unit 440. The RO unit forces water through the membrane by applying pressure to one side of the partial permeation membrane, ideally retaining any solutes on the pressurized side. The RO unit removes particles as small as 26 angstroms, depending on the selectivity of the partial permeation membrane.

[0058] exist Figure 9 In step 530, the fluid flow is treated in UV unit 445. Here, the water flow is exposed to UV light, typically at a wavelength of approximately 254 nm. This destroys viruses and / or bacteria present in the water flow. UV exposure also breaks covalent bonds in organic matter, which facilitates further treatment to reduce TOC content.

[0059] exist Figure 9 In step 535, the fluid flow is processed in SBP unit 450. This unit is used to remove metals and ions from the water flow, as well as other remaining suspended solids or organic matter. The SBP unit has a structure similar to MMF, but with multiple layers of resin acting as adsorbents.

[0060] exist Figure 9In step 540, the fluid flow is processed in MDG unit 455. This unit is used to remove dissolved gases from the water flow. For example, dissolved oxygen reacts with and oxidizes metals used in integrated circuits on semiconductor chips, causing defects. Another example is that dissolved carbon dioxide (and other ions) increases the conductivity of water, which leads to short circuits and other defects within integrated circuits. These gases are removed by replacing them with nitrogen (N2). For example, in the MDG unit, pure nitrogen comes into contact with the water flow through a hydrophobic membrane. Gases can pass through the membrane, but water cannot. This adjusts the gas concentration across the membrane, reducing the O2 concentration in the water flow and increasing the N2 concentration. Figure 9 In step 542, the fluid flow is processed in the second UV unit 457.

[0061] exist Figure 9 In step 545, the fluid flow is processed in CP unit 460. The alert polishing (CP) unit, similar to the SBP unit, is also used to further remove metals and ions present in the water flow. Upstream processes (such as UV units) generate new ions, which the CP unit removes from the water flow. The CP unit can also be considered a second SBP unit, or as a secondary polishing step or a final polishing step. Figure 9 In step 547, the fluid flow is processed in the second MDG unit 462.

[0062] exist Figure 9 In step 550, the fluid flow is processed in UF unit 465. This unit is used to filter very small particles and molecules, down to 2 nanometers (nm). The UF unit is typically the final filtration step in obtaining ultrapure water (UPW). It is also considered that any of these processing steps can be performed again if needed, and / or at different locations in the processing. In step 555, the UPW is then sent to the point of use (POU) 470. In step 560, the UPW is used in semiconductor or display panel manufacturing processes, such as those described above. Figure 5 and Figures 6A-6C As discussed in the article.

[0063] The system disclosed here has several advantages. PFAS contaminants are almost completely removed from the fluid stream, complying with regulatory requirements. No backwashing step is required, resulting in reduced emissions. No chemicals need to be added to capture PFAS, and the generated wastewater stream can be recycled or reused. For example, water emissions are reduced by up to 95% due to reuse in secondary water applications such as cooling towers, local scrubbers, etc. Another example is the ability to recycle up to 400 tons of water per day at a given manufacturing plant while maintaining component yield and achieving significant cost savings.

[0064] Some embodiments disclosed herein therefore relate to a method for removing perfluoroalkyl substances (PFAS) from an initial wastewater stream generated from a semiconductor or display panel manufacturing process. The initial fluid stream is passed through a strongly acidic cation exchange (SAC) unit to obtain an acidic wastewater stream. The acidic wastewater stream is then passed through an activated carbon filter (ACF) unit to remove PFAS.

[0065] Other embodiments disclosed herein relate to a water treatment system for treating wastewater from semiconductor or display panel manufacturing processes, the system including a strongly acidic cation exchange (SAC) unit upstream of an activated carbon filter (ACF) unit.

[0066] The embodiments herein also describe methods for recovering wastewater from semiconductor or display panel manufacturing processes. The wastewater passes through a filter. The wastewater then passes through a strongly acidic cation exchange (SAC) unit to obtain a wastewater stream with an acidic pH. The wastewater stream with the acidic pH then passes through an activated carbon filter (ACF) unit to remove perfluoroalkyl substances (PFAS).

[0067] Various embodiments herein also disclose water treatment systems for producing ultrapure water (UPW). These systems include a strongly acidic cation exchange (SAC) unit upstream of an activated carbon filter (ACF) unit. They also include a filter upstream of the SAC unit; a buffer tank upstream of the SAC unit; and / or multiple ACF units arranged in parallel, such that each ACF unit receives fluid flow from the SAC unit. They further include at least one reverse osmosis (RO) unit; at least one ultraviolet (UV) unit; at least one membrane degassing (MDG) unit; and / or at least one ultrafiltration (UF) unit.

[0068] The methods and systems disclosed herein are further illustrated in the following non-limiting working examples. It should be understood that these examples are for illustrative purposes only, and this disclosure is not intended to be limited to the materials, conditions, process parameters, etc., described herein.

[0069] Figure 10 This is a graph showing the potential of arrival (PoA) versus pH for three different types of activated carbon. This demonstrates the adsorption capacity of activated carbon for PFAS. Types A and B are derived from coconut husks. Type C is derived from bituminous coal. As can be seen here, Type C exhibits a significantly higher PoA across the entire pH range from 3 to 7, particularly in the pH range from 3 to 5.

[0070] Next, combinations of SAC units located directly upstream of ACF units were implemented in the wastewater systems of 11 plants, and the total amount of PFAS in the effluent was measured. The average PFAS removal rate increased by 95.5%, with improvements ranging from 93.3% to 99.6%.

[0071] The features of the above embodiments are designed to facilitate understanding of this disclosure by those skilled in the art. Those skilled in the art should understand that this disclosure can be used as a basis to design and vary other processes and structures to achieve the same purpose and / or the same advantages as the above embodiments. Those skilled in the art should also understand that these equivalent substitutions do not depart from the spirit and scope of this disclosure, and changes, substitutions, or modifications can be made without departing from the spirit and scope of this disclosure.

[0072] Some embodiments disclosed herein pertain to a wastewater treatment method comprising the following steps: Passing an initial wastewater stream through a strong acid cation exchange unit to obtain an acidic wastewater stream. Passing the acidic wastewater stream through at least one activated carbon filter unit to remove perfluoroalkyl substances. In some embodiments, the strong acid cation exchange unit captures tetramethylammonium hydroxide in the initial wastewater stream. In some embodiments, the initial wastewater stream passes through the strong acid cation exchange unit at a linear flow rate of less than 15 m / h. In some embodiments, the acidic wastewater stream passes through at least one activated carbon filter unit at a linear flow rate of less than 5 m / h. In some embodiments, the acidic wastewater stream has a pH of 5 or lower. In some embodiments, at least one activated carbon filter unit comprises activated carbon derived from bituminous coal. In some embodiments, at least one activated carbon filter unit comprises two activated carbon compaction bed stages. In some embodiments, the initial wastewater stream passes through a filter located upstream of the strong acid cation exchange unit. In some embodiments, the acidic wastewater stream is divided into multiple streams, each of which flows through an independent activated carbon filter unit, and the multiple activated carbon filter units are arranged in parallel with each other.

[0073] Some embodiments of this disclosure pertain to a water treatment system comprising a wastewater production apparatus and a strong acid cation exchange unit. The strong acid cation exchange unit receives the wastewater and is located upstream of at least one activated carbon filter unit. In some embodiments, the water treatment system further includes a filter located upstream of the strong acid cation exchange unit. In some embodiments, the water treatment system further includes a buffer tank located upstream of the strong acid cation exchange unit. In some embodiments, the water treatment system has a plurality of activated carbon filter units arranged in parallel, such that each of the plurality of activated carbon filter units can receive a fluid flow from the strong acid cation exchange unit. In some embodiments, at least one activated carbon filter unit comprises activated carbon derived from bituminous coal. In some embodiments, at least one activated carbon filter unit comprises two activated carbon compaction bed stages.

[0074] Some embodiments disclosed herein pertain to a wastewater treatment method comprising the following steps: passing wastewater through a filter; passing the wastewater through a strong acid cation exchange unit to obtain an acidic wastewater stream with an acidic pH value; passing the acidic wastewater stream with the acidic pH value through at least one activated carbon filter unit to remove perfluoroalkyl substances. In some embodiments, the wastewater treatment method further comprises sending the wastewater stream from the at least one activated carbon filter unit to a recovery tank. In some embodiments, the wastewater passes through the strong acid cation exchange unit at a linear flow rate of less than 15 m / h. In some embodiments, the acidic wastewater stream passes through the at least one activated carbon filter unit at a linear flow rate of less than 5 m / h. In some embodiments, the at least one activated carbon filter unit comprises activated carbon derived from bituminous coal.

Claims

1. A water treatment system, characterized in that, include: Manufacturing tools that generate wastewater; A strong acid cation unit receives the wastewater and includes an ion exchange layer for treating the wastewater into an acidic wastewater stream. as well as At least one activated carbon filter unit is located downstream of the strong acid cation unit, and the at least one activated carbon filter unit includes at least one activated carbon compacted bed stage for adsorbing perfluoroalkyl substances present in the acidic wastewater stream.

2. The water treatment system according to claim 1, characterized in that, It also includes a filter located upstream of the strong acid cation unit.

3. The water treatment system according to claim 1, characterized in that, It also includes a buffer tank located upstream of the strong acid cation unit.

4. The water treatment system according to claim 1, wherein the water treatment system has a plurality of activated carbon filter units arranged in parallel, such that each of the plurality of activated carbon filter units receives the acidic wastewater flow from the strong acid cation unit.

5. The water treatment system according to claim 4, characterized in that, it further... include: A recovery tank is located downstream of the plurality of activated carbon filter units, wherein wastewater flows from the plurality of activated carbon filter units are merged in the recovery tank.

6. The water treatment system according to claim 1, wherein the at least one activated carbon filter unit comprises two activated carbon compacted bed stages.

7. The water treatment system according to claim 1, characterized in that, Also includes: The wastewater tank is located downstream of the at least one activated carbon filter unit.

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