Lens polishing machine wastewater treatment system and treatment method

Abstract

This application relates to a wastewater treatment system and method for lens polishing machines, comprising: a primary sedimentation tank for primary physical sedimentation of polishing liquid; a primary filter connected to the primary sedimentation tank via a pump, configured to perform preliminary filtration of the polishing machine wastewater after primary physical sedimentation; and a secondary filter connected to the primary filter via a pump, configured to perform secondary filtration of the pre-filtered polishing machine wastewater. Each unit of the invention is sequentially connected to the pump via pipelines to form a closed-loop treatment system. The system employs a two-stage precision filtration combined with physical sedimentation technology to efficiently remove micron and nano-sized polishing powder, ensuring effluent meets discharge standards. Furthermore, it integrates an automatic backwashing function to prevent filter element clogging, extend filter element lifespan, and reduce maintenance costs. Additionally, it includes a sludge chemical treatment unit to achieve sludge reduction and harmlessness, avoiding secondary pollution.

Description

Technical Field

[0001] This invention relates to a wastewater treatment system and method for lens polishing machines, belonging to the field of industrial wastewater treatment and environmental engineering technology. Background Technology

[0002] With the development of industries such as semiconductors, precision optics, and automobile manufacturing, processes such as chemical mechanical polishing (CMP) are widely used, generating a large amount of complex and highly polluting waste liquid. This waste liquid mainly originates from coolants, lubricants, chemical polishing agents, and rinsing water used in the workpiece grinding and polishing process. It typically contains high concentrations of suspended solids, heavy metal ions, organic pollutants, recalcitrant complexes, and acidic and alkaline substances. In particular, the polishing process for optical lenses involves the use of polishing machines, resulting in the generation of large amounts of polishing waste liquid. If discharged directly without proper treatment, this will lead to water turbidity, accumulation of ecotoxicities, and soil pollution, seriously threatening the environment and human health.

[0003] Currently, the mainstream methods for treating polishing waste liquid from polishing machines include:

[0004] 1. Physical method: Sand filtration, activated carbon filtration or membrane separation (ultrafiltration, reverse osmosis) are used to further remove particulates and dissolved organic matter.

[0005] 2. Chemical methods: Neutralization is achieved by using lime, sodium hydroxide, etc., to adjust the pH to neutral, reducing corrosiveness and promoting the precipitation of metal hydroxides; or by adding sulfides or iron salts to chemically precipitate heavy metals into insoluble sulfides or coprecipitates; or by using advanced oxidation methods such as Fenton's reagent or ozone catalytic oxidation to destroy the molecular structure of organic matter and improve biodegradability.

[0006] 3. Biological method: This method is used less frequently. For wastewater with low organic matter concentration and good biodegradability, activated sludge or biofilm methods can be used for degradation.

[0007] The main drawbacks of the three commonly used methods mentioned above are as follows: For physical methods, the particle size in the polishing waste liquid is mostly in the micrometer or even nanometer range, and some of them are charged. Traditional sedimentation processes are difficult to effectively aggregate them, which can easily lead to excessive suspended solids (SS) in the effluent. At the same time, conventional chemical precipitation cannot completely remove them, requiring additional complexation breaking steps, which increases chemical consumption and process complexity, and the cost of chemical treatment is also high. While membrane separation in biological methods can improve the quality of effluent, it is easily contaminated by suspended solids and organic matter, requiring frequent cleaning or replacement, which increases the burden of operation and maintenance.

[0008] In summary, existing processes suffer from incomplete treatment, complex procedures, high costs, and susceptibility to clogging, failing to meet the demands for continuous, efficient, and low-cost treatment of optical lens polishing wastewater. Therefore, developing a simple, highly accurate, and easily maintainable wastewater treatment system and method for lens polishing machines has become a pressing technical challenge in this field. Summary of the Invention

[0009] In view of the problems existing in the background technology, the technical solution of this application aims to provide a lens polishing machine wastewater treatment system and treatment method that can combine physical, chemical and biological methods, shorten the treatment cycle in the treatment process, reduce treatment costs and simplify the process.

[0010] An embodiment of the first aspect of this application provides a wastewater treatment system for a lens polishing machine, comprising:

[0011] Primary sedimentation tank, in which the polishing fluid undergoes primary physical sedimentation;

[0012] The primary filter, connected to the primary sedimentation tank via a pump, is configured to perform preliminary filtration of polishing machine wastewater that has undergone primary physical sedimentation.

[0013] The secondary filter, connected to the primary filter via a pump, is configured to perform secondary filtration of the polishing machine wastewater that has undergone preliminary filtration.

[0014] In some embodiments, the primary sedimentation tank is a primary sedimentation tank in which the polishing slurry stock solution is discharged and transferred through a pipeline, and primary physical sedimentation is completed in the primary sedimentation tank.

[0015] In some embodiments, the primary filter is a primary bag filter, comprising:

[0016] Filter cylinder I;

[0017] The filter bag, installed inside filter housing I, is configured to filter polishing machine wastewater down to 0.1 microns.

[0018] Specifically, because physical sedimentation is required first, followed by biofilm treatment, it is divided into a two-stage sedimentation method.

[0019] In some embodiments, the secondary filter is a secondary ultrafine filter, comprising:

[0020] Filter cylinder II;

[0021] The ultra-fine filter element, installed inside filter housing II, is configured to filter polishing machine wastewater down to 0.01 microns after it has passed through the primary filter.

[0022] In some embodiments, a backwasher is also included, configured to work in conjunction with a secondary filter and capable of pumping backwash liquid after backwashing back into the primary sedimentation tank for physical settling.

[0023] In some embodiments, a secondary sedimentation tank is also included, configured to be used in conjunction with the primary sedimentation tank, and capable of pumping the sludge settled in the primary sedimentation tank into the secondary sedimentation tank for reaction and treatment.

[0024] An embodiment of the first aspect of this application provides a method for treating wastewater from a lens polishing machine, comprising the following steps:

[0025] The polishing machine wastewater is transferred to a primary sedimentation tank for first-stage physical sedimentation.

[0026] When the supernatant level in the initial sedimentation tank reaches the overflow port, the supernatant is transferred to the primary filter by the pump for coarse filtration.

[0027] After being filtered by the primary filter, the supernatant is pumped back into the secondary filter for fine filtration, and the filtered water is then discharged into the sewage network.

[0028] In some embodiments, a backwashing step is also included, including...

[0029] Backwashing determination: If the discharge flow rate of the flow meter installed at the downstream end of the ultrafiltration unit is less than 1 m³ / h or the drainage pressure is higher than 2.5 bar after cleaning, then the ultrafiltration element backwashing operation will be initiated.

[0030] If cleaning is required, clean water is pumped into the secondary filter to backwash the ultrafine filter element, and the backwash solution is pumped back into the primary sedimentation tank for primary physical sedimentation.

[0031] In some embodiments, the method further includes a step of secondary treatment of the sludge in the primary sedimentation tank, specifically: setting up a secondary sedimentation tank, and using a sludge pump to transfer the sludge in the primary sedimentation tank into the secondary sedimentation tank for reaction and disposal.

[0032] In some embodiments, the reaction carried out in the secondary settling tank is as follows:

[0033] Al2O3 + 2NaOH = 2NaAlO2 + H2O.

[0034] In this embodiment, the main innovation is the combination of physical, chemical and biological treatment methods, which optimizes the polishing slurry waste liquid treatment process, simplifies the process system, improves treatment efficiency and shortens the treatment cycle.

[0035] This invention proposes a wastewater treatment system for a lens polishing machine, comprising a primary sedimentation unit, a first-stage filtration unit, a second-stage filtration unit, a backwashing unit, and a sludge treatment unit. Each unit is sequentially connected to a pump via pipelines, forming a closed-loop treatment system. It employs a two-stage precision filtration combined with physical sedimentation technology to efficiently remove micron- and nano-sized polishing powders, ensuring effluent meets discharge standards. Furthermore, it integrates an automatic backwashing function to prevent filter clogging, extend filter life, and reduce maintenance costs. Additionally, it includes a sludge chemical treatment unit to reduce and render harmless the sludge, preventing secondary pollution.

[0036] In summary, the system boasts a simple structure, high degree of automation, and short processing flow, making it suitable for continuous operation in industrial settings and demonstrating great promise for industrial applications. Attached Figure Description

[0037] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0038] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of this application.

[0039] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0040] When using the terms “including,” “having,” and “comprising” as described herein, another component may be added unless explicitly qualifying terms such as “only,” “consisting of,” etc. are used. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0041] It should be understood that although the terms “first,” “second,” etc., may be used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of this application, a first element may be referred to as a second element, and similarly, a second element may be referred to as a first element.

[0042] It should also be understood that, in interpreting an element, although not explicitly described, the element is interpreted as including a range of error, which should be within the acceptable deviation range of a particular value as determined by a person skilled in the art. For example, "approximately," "about," or "substantially" can mean within one or more standard deviations, without limitation herein.

[0043] Furthermore, the accompanying drawings are not drawn to a 1:1 scale, and the relative dimensions of the components are shown in the drawings only as examples and not necessarily to actual scale.

[0044] Reference Figure 1 As shown, in response to the problem of polishing wastewater treatment in the lens polishing machine of this application, the inventors' team proposed a method combining physical, chemical, and biological technologies. Specifically, a physical sedimentation module is designed as the primary sedimentation treatment; a secondary biological treatment module is designed, which, combined with the characteristics of the polishing wastewater, is divided into two secondary combined treatment modules; and finally, a chemical treatment module is designed. Because sludge is generated during the primary sedimentation treatment in the primary sedimentation tank, the sludge needs to be treated quickly through chemical methods. This forms the core technical solution of this application: a comprehensive treatment system integrating physical, biological, and chemical technologies.

[0045] It should also be noted that this system also involves a backwashing module. The backwashing module is designed to better protect the performance of the biofilter adsorber, while also improving the overall system's lifespan and reducing the failure rate.

[0046] Specifically, regarding the main innovative technical ideas of this application, the first aspect of this application provides a wastewater treatment system for lens polishing machines, particularly suitable for the purification and treatment of wastewater containing micron- and nano-sized suspended particles and alumina polishing powder generated from chemical mechanical polishing (CMP) of optical lenses and semiconductor wafers. This system falls within the scope of environmental engineering and precision manufacturing supporting water treatment technologies. Its features include:

[0047] Primary sedimentation tank, in which the polishing fluid undergoes primary physical sedimentation;

[0048] In some embodiments, the primary sedimentation tank is a conical tonne tank, through which the wastewater from the intermediate polishing machine is discharged for primary physical sedimentation. In specific implementation, the raw polishing liquid is discharged through a pipeline to the "intermediate tonne tank" for initial sedimentation treatment. When the liquid level in the "intermediate tonne tank" reaches the upper limit, the upper clean water is pumped into the "conical tonne tank" for discharge treatment using a self-priming pump. The bottom sediment is finally pumped to the "disposal tonne tank" by a sludge pump for disposal.

[0049] Specifically, the conical ton tank is equipped with an inlet and an overflow outlet at the top, and a sludge discharge outlet at the bottom. A level sensor is installed inside the tank to monitor the supernatant level. After the polishing machine wastewater enters the primary sedimentation tank, it undergoes primary physical sedimentation under gravity, with large abrasive particles and sludge settling to the bottom. The supernatant is discharged through the overflow outlet. A level gauge is also installed to indicate the liquid level in the overflow outlet. When the liquid level in the conical ton tank reaches the upper limit (overflow outlet position), the centrifugal pump automatically starts.

[0050] A primary filter, connected to the primary sedimentation tank via a pump, is configured to perform preliminary filtration of the polishing machine wastewater after primary physical sedimentation; the primary filter is a primary bag filter, comprising:

[0051] Filter cylinder I is connected to the overflow port of the primary sedimentation tank via a centrifugal pump;

[0052] The filter bag, installed inside the filter cylinder I, is configured to filter the polishing machine wastewater down to 0.1 microns, and is used to trap micron-sized suspended particles remaining after settling, thus achieving preliminary filtration.

[0053] The secondary filter, connected to the primary filter via a pump, is configured to perform secondary filtration of the polishing machine wastewater that has undergone preliminary filtration.

[0054] The secondary filter is a secondary ultra-fine filter, comprising:

[0055] Filter cylinder II;

[0056] The ultra-fine filter element, installed inside filter housing II, is configured to filter polishing machine wastewater down to 0.01 microns after it has passed through the primary filter.

[0057] In some specific embodiments, a backwasher is also included, configured to work in conjunction with a secondary filter and capable of pumping backwash liquid after backwashing back into the primary sedimentation tank for physical settling.

[0058] Specifically, the backwashing unit includes a backwashing pump, a clean water tank, a flow meter, and a pressure sensor. The flow meter and pressure sensor are installed at the outlet of the secondary ultrafine filter, and the backwashing pump is connected to both the clean water tank and the secondary ultrafine filter. When the outlet flow rate is ≤1m³ / h or the outlet pressure is ≥2.5bar, backwashing is automatically started, and clean water backwashes the ultrafine filter element. The backwash liquid is returned to the primary sedimentation tank for re-settling, thus achieving water reuse.

[0059] In some specific embodiments, the secondary sedimentation tank is a treatment ton, which is configured to be used in conjunction with the primary sedimentation tank. It can pump the sludge settled in the primary sedimentation tank into the secondary sedimentation tank for reaction and treatment. When the sediment in the conical ton reaches the suction port of the centrifugal pump, the sludge pump is turned on to pump the sediment to the treatment ton for disposal.

[0060] Specifically, a sludge pump connects the primary sedimentation tank to the sludge discharge outlet at the bottom. Sodium hydroxide solution is added to the secondary sedimentation tank, causing a chemical reaction between the alumina in the primary sedimentation tank sludge and the sodium hydroxide. The reaction equation is: Al₂O₃ + 2NaOH = 2NaAlO₂ + H₂O. This converts solid alumina into soluble sodium aluminate, achieving sludge reduction and harmless treatment.

[0061] On the other hand, regarding the aforementioned processing system, this application also discloses a second aspect: a method for treating wastewater from a lens polishing machine, comprising the following steps:

[0062] The polishing wastewater is transferred to the primary sedimentation tank for primary physical sedimentation. The polishing wastewater enters the primary sedimentation tank through the inlet and settles for 30 minutes. The supernatant is then brought to the upper limit of the liquid level sensor.

[0063] When the supernatant level in the initial sedimentation tank reaches the overflow port, the supernatant is transferred to the primary filter by the pump for coarse filtration; the centrifugal pump pumps the supernatant into the primary bag coarse filter to remove micron-sized particles.

[0064] After being filtered by the primary filter, the supernatant is pumped back into the secondary filter for fine filtration, and the filtered water is discharged into the sewage network. The sewage first passes through the primary bag filter (precision: 0.1 microns), and then through the secondary ultrafine filter (precision: 0.01 microns). Finally, the booster pump pumps the wastewater into the secondary ultrafine filter, and the filtered water is discharged into the network through the outlet. The treated water is directly discharged into the sewage network.

[0065] In some specific embodiments, a backwashing step is also included, including

[0066] Backwashing is determined by the following criteria: if the flow rate observed after backwashing is less than 1 m³ / h or the drainage pressure is higher than 2.5 bar (normal flow rate is 4-5 m³ / h), then the ultrafine filter cartridge backwashing operation is initiated. In some specific embodiments, when the outflow rate is less than 0.8 m³ / h or the pressure is higher than 2.5 bar after backwashing, the filter cartridge needs to be replaced.

[0067] If cleaning is required, clean water is pumped into the secondary filter to backwash the ultrafine filter element, and the backwash solution is pumped back into the primary sedimentation tank for primary physical sedimentation.

[0068] Specifically, the backwash pump is started to pump the clean water in the clear water tank back into the secondary ultrafine filter to flush the ultrafine filter element; the backwash liquid is returned to the primary sedimentation tank for primary physical sedimentation to avoid water waste.

[0069] When the liquid level in the primary sedimentation tank reaches the suction port of the primary pump, start the sludge pump to pump the sludge into the secondary sedimentation tank. Add approximately 1 kg of sodium hydroxide granules at a ratio of 1:1000 to the secondary sedimentation tank and stir. Adjust the pH value to 9-10 so that the alumina reacts with the sodium hydroxide to convert the solid sludge into a soluble solution, thus completing the harmless treatment of the sludge.

[0070] As needed, the sludge pump can be started weekly to pump the sludge from the primary sedimentation tank into the secondary sedimentation tank, add 10% NaOH solution, and react for 2 hours to complete the sludge treatment.

[0071] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0072] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A wastewater treatment system for a lens polishing machine, characterized in that, include: Primary sedimentation tank, in which the polishing fluid undergoes primary physical sedimentation; The primary filter, connected to the primary sedimentation tank via a pump, is configured to perform preliminary filtration of polishing machine wastewater that has undergone primary physical sedimentation. The secondary filter, connected to the primary filter via a pump, is configured to perform secondary filtration of the polishing machine wastewater that has undergone preliminary filtration.

2. The wastewater treatment system for a lens polishing machine according to claim 1, characterized in that, The primary filter is a primary bag filter, comprising: Filter cylinder I; The filter bag, installed inside filter housing I, is configured to filter polishing machine wastewater down to 0.1 microns.

3. The wastewater treatment system for a lens polishing machine according to claim 1, characterized in that, The secondary filter is a secondary ultra-fine filter, comprising: Filter cylinder II; The ultra-fine filter element, installed inside filter housing II, is configured to filter polishing machine wastewater down to 0.01 microns after it has passed through the primary filter.

4. The wastewater treatment system for a lens polishing machine according to claim 1, characterized in that, It also includes a backwasher, configured to work in conjunction with a secondary filter, and capable of pumping the backwash liquid back into the primary sedimentation tank for physical settling after backwashing.

5. The wastewater treatment system for a lens polishing machine according to claim 1, characterized in that, It also includes a secondary sedimentation tank, which is configured to be used in conjunction with the primary sedimentation tank and can pump the sludge settled in the primary sedimentation tank into the secondary sedimentation tank for reaction and treatment.

6. A method for treating wastewater from a lens polishing machine, characterized in that, Includes the following steps: The polishing machine wastewater is transferred to a primary sedimentation tank for first-stage physical sedimentation. When the supernatant level in the initial sedimentation tank reaches the upper limit position of the level sensor, the supernatant is transferred to the primary filter by the pump for coarse filtration. After being filtered by the primary filter, the supernatant is pumped back into the secondary filter for fine filtration, and the filtered water is then discharged into the sewage network.

7. The method for treating wastewater from a lens polishing machine according to claim 6, characterized in that, It also includes a backwashing step, including Backwashing determination: If the discharge flow rate of the flow meter installed at the downstream end of the ultrafiltration unit is less than 1 m³ / h or the drainage pressure is higher than 2.5 bar after cleaning, then the ultrafiltration element backwashing operation will be initiated. If cleaning is required, clean water is pumped into the secondary filter to backwash the ultrafine filter element, and the backwash solution is pumped back into the primary sedimentation tank for primary physical sedimentation.

8. The method for treating wastewater from a lens polishing machine according to claim 7, characterized in that, It also includes a secondary treatment step for the sludge in the primary sedimentation tank, specifically: setting up a secondary sedimentation tank, and using a sludge pump to transfer the sludge in the primary sedimentation tank into the secondary sedimentation tank for reaction and disposal.

9. A method for treating wastewater from a lens polishing machine according to claim 8, characterized in that, The reaction that takes place in the secondary settling tank is as follows: Al2O3 + 2NaOH = 2NaAlO2 + H2O.

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