Concentrated alkali wastewater resource utilization system in solar cell production
By combining a system for collecting, pretreating, separating, and adjusting the concentration of concentrated alkali wastewater, the problems of equipment blockage and high costs in the treatment of concentrated alkali wastewater are solved, achieving efficient resource utilization and improving the alkali recovery efficiency and environmental protection level.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- KAIDE ELECTRONIC ENG DESIGN CO LTD
- Filing Date
- 2025-04-17
- Publication Date
- 2026-05-12
AI Technical Summary
Existing technologies for treating concentrated alkaline wastewater suffer from problems such as membrane clogging risk, large footprint, high treatment cost, low recovery efficiency, and high energy consumption, making it difficult to effectively utilize resources.
The system employs a combination of a concentrated alkaline wastewater collection module, a pretreatment module, a membrane separation module, a reuse module, and a permeate treatment module. Through sedimentation, pH adjustment, membrane separation, and concentration adjustment, it achieves the resource utilization of concentrated alkaline wastewater, avoids equipment blockage, and improves the purity of the alkaline solution.
This technology enables the efficient recycling and utilization of concentrated alkaline wastewater, improves the utilization rate of alkali solution, reduces pollutant emissions, lowers treatment costs, aligns with the concept of green manufacturing, and enhances the competitiveness of enterprises.
Smart Images
Figure CN224226829U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of industrial wastewater treatment, specifically a system for the resource utilization of concentrated alkaline wastewater from solar cell production. Background Technology
[0002] Currently, in the photovoltaic industry, concentrated alkaline wastewater is generally treated using traditional physicochemical methods. This involves collecting the concentrated alkaline wastewater generated in the workshop separately to a wastewater treatment plant, where it enters a regulating tank and is then neutralized with concentrated acid wastewater. The mixture undergoes processes such as defluorination, desiliconization, and hardness removal to precipitate silicates. The effluent, once meeting standards, is then directly discharged. This treatment method has certain drawbacks. When mixing concentrated alkaline and concentrated acid wastewater, a specific ratio is required. Excessive mixing can easily lead to silicate crystal formation, increasing the pressure on downstream treatment systems and potentially causing membrane clogging if a membrane system is present. Furthermore, concentrated alkaline wastewater requires separate collection and regulating tanks, necessitating a larger wastewater treatment plant area and increasing wastewater treatment costs.
[0003] With increasing emphasis on green development in recent years, some factories have begun exploring methods for recycling concentrated alkaline wastewater and utilizing it as a resource. Common methods include evaporation crystallization, where the concentrated alkaline wastewater is evaporated and crystallized, precipitating out as crystals. Another approach involves using ion exchange resins, which adsorb alkaline ions from the wastewater. Once the resin is saturated, a regeneration process washes away the alkaline ions, thus recovering the alkaline solution. However, these recycling methods still have certain drawbacks, including high technical difficulty and cost, high energy consumption, carbon emissions, low recycling efficiency, and difficulty in handling impurities. Utility Model Content
[0004] Therefore, in order to overcome the above-mentioned shortcomings, this utility model provides a concentrated alkaline wastewater resource utilization system for solar cell production. It is used to collect and reuse alkaline water in the production process of TOPCon (Tunnel Oxide Passivated Contact) solar cells. By pre-treating the wastewater, the blockage of transport pipelines by particles in the waste liquid and the impact on the reuse equipment are avoided. Concentrated alkaline liquid is obtained through concentration and separation, so that the alkaline water can be reused by the reuse equipment.
[0005] Specifically, a system for the resource utilization of concentrated alkaline wastewater from solar cell production includes...
[0006] Concentrated alkaline wastewater collection module, used to collect concentrated alkaline wastewater;
[0007] The pretreatment module is connected to the concentrated alkaline wastewater collection module and is used to perform sedimentation treatment and pH adjustment on the collected concentrated alkaline wastewater.
[0008] A membrane separation module, connected to the pretreatment module, is used for membrane separation of the pretreated concentrated alkaline wastewater;
[0009] A reuse module, connected to the membrane separation module, is used to reuse the concentrated alkali after membrane separation; and
[0010] The permeate treatment module is connected to the membrane separation module and is used to re-treat the permeate after membrane separation before discharge.
[0011] Optionally, the system further includes a concentration adjustment module connected between the membrane separation module and the reuse module. The concentration adjustment module mixes the recovered alkali solution with the fresh alkali solution to change the alkali solution concentration to meet the alkali solution concentration requirements of the reuse module.
[0012] Optionally, the pretreatment module includes a sedimentation tank, in which a filter frame is provided on the inlet side, and the sedimentation tank has an adjustment unit for adjusting the pH of the liquid.
[0013] Optionally, the regulating unit includes a stirrer, a pH monitor, and a reagent dosing area.
[0014] Optionally, the reuse module is an acid-base scrubbing tower from the TOPCon battery production process.
[0015] This utility model has the following advantages:
[0016] This invention relates to a system for the resource utilization of concentrated alkaline wastewater from solar cell production. It collects and reuses alkaline water generated during the production of TOPCon (Tunnel Oxide Passivated Contact) solar cells. Pretreatment of the wastewater prevents particles in the waste liquid from clogging transport pipelines and affecting recycling equipment. Concentrated alkaline liquid is obtained through concentration and separation, facilitating reuse in the recycling equipment. This system achieves the recycling of concentrated alkaline wastewater, improving alkali utilization efficiency, realizing resource recycling, and reducing pollutant emissions.
[0017] The pretreatment module removes impurities from concentrated alkaline wastewater, which contains silicates, metal ions (such as aluminum and iron), particulate matter, and organic matter. These impurities affect the quality of the recovered alkali solution, thus impacting the cleaning effect of the reuse module (acid-alkali scrubbing tower). The pretreatment module performs sedimentation and filtration on the wastewater, while membrane separation modules (such as nanofiltration and reverse osmosis) remove impurities to ensure the purity of the recovered alkali solution.
[0018] Since the concentration of the recovered alkali solution may be unstable, both excessively high and low concentrations can affect the process efficiency of the reuse module (acid-alkali washing tower). The concentration of the concentrate is precisely controlled by a concentration adjustment module connected to the membrane separation module. The recovered alkali solution is mixed with fresh alkali solution and adjusted to the required concentration (e.g., 5%-15%).
[0019] Impurities (such as silicates and metal ions) in concentrated alkaline wastewater can cause corrosion and blockage of acid-alkali scrubbing towers and related equipment. Therefore, filtration and sedimentation in the pretreatment module can remove impurities and optimize equipment materials (such as using corrosion-resistant materials).
[0020] Because the permeate produced after membrane separation in the membrane separation module contains low concentrations of impurities, further treatment is required to meet discharge or reuse standards. The permeate treatment module performs biochemical or advanced oxidation treatment on the permeate to ensure it meets environmental emission standards. Attached Figure Description
[0021] Figure 1 This is a structural block diagram of the concentrated alkaline wastewater resource utilization system in the production of solar cells according to the present invention;
[0022] Figure 2 This is a schematic diagram of the preprocessing module described in this utility model;
[0023] Figure 3 This is a cross-sectional schematic diagram of the preprocessing module shown in this utility model;
[0024] In the diagram: 100, concentrated alkaline wastewater collection module; 200, concentrated alkaline wastewater collection module; 300, pretreatment module; 301, sedimentation tank; 302, filter frame; 303, stirrer; 304, reagent dosing area; 400, membrane separation module; 500, reuse module; 600, permeate treatment module; 700, concentration adjustment module. Detailed Implementation
[0025] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.
[0026] In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, without necessarily requiring or implying any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.
[0027] As mentioned in the background section, with the increasing emphasis on green development in recent years, some factories have begun to explore methods for recovering concentrated alkaline wastewater and utilizing it as a resource. Common methods include evaporation crystallization, where the concentrated alkaline wastewater is evaporated and crystallized, precipitating out as crystals. Another approach involves using ion exchange resins, which adsorb alkaline ions from the wastewater. Once the resin is saturated, the alkali ions are eluted through a regeneration process, thus recovering the alkaline solution. However, these recovery methods still have certain drawbacks, including high technical difficulty and cost, high energy consumption, carbon emissions, low recovery efficiency, and difficulty in handling impurities.
[0028] Based on the above problems, this embodiment provides a system for the resource utilization of concentrated alkaline wastewater in solar cell production, such as... Figure 1 As shown, the system includes:
[0029] Concentrated alkaline wastewater collection module 200, used to collect concentrated alkaline wastewater 100;
[0030] The pretreatment module 300 is connected to the concentrated alkaline wastewater collection module and is used to perform sedimentation treatment and pH adjustment on the collected concentrated alkaline wastewater.
[0031] The membrane separation module 400 is connected to the pretreatment module and is used for membrane separation of the pretreated concentrated alkaline wastewater.
[0032] The reuse module 500 is connected to the membrane separation module and is used to reuse the concentrated alkali after membrane separation.
[0033] A permeate treatment module 600, connected to the membrane separation module, is used to further treat the permeate after membrane separation before discharge; and
[0034] A concentration adjustment module 700 is connected between the membrane separation module and the reuse module. The concentration adjustment module mixes the recovered alkali solution with the fresh alkali solution to change the concentration of the alkali solution, so as to meet the needs of the reuse module for the concentration of the alkali solution.
[0035] The aforementioned technical features enable the collection and reuse of alkaline wastewater generated during the production of TOPCon (Tunnel Oxide Passivated Contact) solar cells (e.g., trough-type alkaline polishing and cleaning, RCA cleaning, quartz boat cleaning, etc.). Pre-treatment of the wastewater prevents particles in the waste liquid from clogging transport pipelines and affecting reuse equipment. Concentrated alkaline liquid is obtained through concentration and separation, facilitating reuse in the equipment. This achieves the recycling of concentrated alkaline wastewater, improving alkali utilization, realizing resource recycling, and reducing pollutant emissions. In operation, concentrated alkaline wastewater is collected through the concentrated alkaline wastewater collection module. After collection, it undergoes initial sedimentation, followed by further sedimentation and filtration in a pretreatment sedimentation tank. The pH value of the concentrated alkaline wastewater is then adjusted. The pretreated concentrated alkaline wastewater enters the membrane separation module, where it is separated into alkaline solution and permeate. The alkaline solution is adjusted in concentration by the concentration adjustment module and then sent to the reuse module for the reuse of waste alkali. The permeate enters the permeate treatment module, where it undergoes biochemical treatment or advanced oxidation treatment to ensure compliance with environmental emission standards.
[0036] To enable the pretreatment module to pretreat concentrated alkaline wastewater, in one embodiment, the pretreatment module includes a sedimentation tank 301, with a filter frame 302 installed on the inlet side of the sedimentation tank. The sedimentation tank has an adjustment unit for adjusting the pH of the liquid. The adjustment unit includes a stirrer 303, a pH monitor 305, and a reagent dosing area 304.
[0037] The stirrer is used to adjust the pH value. After the reagent (acid or alkali) is added, it is stirred to make the liquid uniform. After the specified pH value is reached, stirring is stopped, and precipitation begins. After the specified precipitation time, the supernatant is discharged to the membrane separation module.
[0038] For example, the membrane separation module is an existing device employing membrane separation technology (such as nanofiltration or reverse osmosis). Optionally, the operating pressure of this device can be 0.5-2.0 MPa, and the temperature can be 20-40℃, yielding a concentrated solution (NaOH or KOH concentration of 5-15%) and a permeate. The concentration of the NaOH or KOH concentrated solution obtained from membrane separation is then adjusted by a concentration adjustment module (e.g., NaOH concentration of 10%).
[0039] For example, the reuse module is an acid-alkali washing tower in the TOPCon battery production process, used for cleaning and texturing silicon wafers. The acid-alkali washing tower is mainly used for cleaning and surface treatment of silicon wafers, and the use of concentrated alkali (such as NaOH or KOH) is one of the key steps in the cleaning process. Typically, a 1%-10% NaOH or KOH solution is used, the alkali washing temperature is generally 50-80℃, and the alkali washing time is usually several minutes to over ten minutes. The following is the principle and function of using concentrated alkali in the acid-alkali washing tower:
[0040] (1) Surface etching: Silicon (Si) reacts with sodium hydroxide (NaOH) to produce sodium silicate (Na2SiO3) and hydrogen (H2), which can remove the damaged layer and oxide layer on the surface, forming a clean and activated surface.
[0041] Si + 2NaOH + H₂O → Na₂SiO₃ + 2H₂↑
[0042] (2) Removal of surface contaminants: Organic matter, particulate matter, metallic impurities, etc. may adhere to the surface of silicon wafers. Concentrated alkali can dissolve or decompose these contaminants. The following is a method for using concentrated alkali to saponify organic contaminants (such as grease, photoresist residue, etc.) on the surface of silicon wafers, decomposing them into water-soluble substances.
[0043] R-COOH + NaOH → R-COONa + H₂O
[0044] Concentrated alkali can also react with certain metal ions (such as aluminum and iron) to form soluble compounds, thereby removing metal impurities.
[0045] Al₂O₃ + 2NaOH → 2NaAlO₂ + H₂O
[0046] Adjusting surface morphology: By controlling the concentration and temperature of the alkaline solution, the microstructure of the silicon wafer surface can be adjusted, providing favorable surface conditions for subsequent processes (such as diffusion, coating, etc.).
[0047] The concentrated alkaline wastewater resource utilization system described in this embodiment significantly reduces the consumption of fresh alkali solution and improves resource utilization efficiency by recovering NaOH / KOH from the concentrated alkaline wastewater. Reusing the recovered alkali solution reduces the procurement cost of fresh alkali solution and lowers wastewater treatment costs. By recovering and reusing concentrated alkaline wastewater, the discharge of high-concentration alkaline wastewater is significantly reduced, thus lowering environmental pollution. The recovery process removes pollutants such as silicates and metal ions from the wastewater, reducing the difficulty and cost of subsequent wastewater treatment. This aligns with the concepts of green manufacturing and sustainable development, helping to enhance the company's social image and brand value. Through the resource utilization of concentrated alkaline wastewater, companies can reduce production costs, improve environmental protection standards, and thus enhance market competitiveness.
[0048] The above description of the disclosed embodiments enables those skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A system for the resource utilization of concentrated alkaline wastewater in solar cell production, characterized in that: include Concentrated alkaline wastewater collection module, used to collect concentrated alkaline wastewater; The pretreatment module is connected to the concentrated alkaline wastewater collection module and is used to perform sedimentation treatment and pH adjustment on the collected concentrated alkaline wastewater. A membrane separation module, connected to the pretreatment module, is used for membrane separation of the pretreated concentrated alkaline wastewater; The reuse module is connected to the membrane separation module and is used to reuse the concentrated alkali after membrane separation. as well as The permeate treatment module is connected to the membrane separation module and is used to re-treat the permeate after membrane separation before discharge.
2. The system for resource utilization of concentrated alkaline wastewater in solar cell production according to claim 1, characterized in that: It also includes a concentration adjustment module, which is connected between the membrane separation module and the reuse module.
3. The system for resource utilization of concentrated alkaline wastewater in solar cell production according to claim 1, characterized in that: The pretreatment module includes a sedimentation tank, in which a filter frame is provided on the inlet side, and the sedimentation tank has an adjustment unit for adjusting the pH value of the liquid.
4. The system for resource utilization of concentrated alkaline wastewater in solar cell production according to claim 3, characterized in that: The regulating unit includes a stirrer, a pH monitor, and a reagent dosing area.
5. The system for resource utilization of concentrated alkaline wastewater in solar cell production according to claim 1, characterized in that: The reuse module is the acid-base washing tower used in the TOPCon battery production process.