Pretreatment process for recycling wastewater and reclaimed water of silicon solar cell

Abstract

The invention discloses a pretreatment process for water reuse of silicon solar cell wastewater, which comprises a collection device, the output end of the collection device is communicated with a pretreatment device 1, the output end of the pretreatment device 1 is communicated with a pretreatment device 2, the output end of the pretreatment device 2 is communicated with a pretreatment device 3, and the output end of the pretreatment device 3 is communicated with a pretreatment device 4. The output end of the pretreatment device 3 is communicated with a rear-end reclaimed water recycling membrane system. The method has the advantages that specific pollutants influencing the reclaimed water reuse membrane system are subjected to targeted grading pretreatment, a new thought is provided for recycling of the silicon solar cell wastewater, and remarkable environmental benefits and economic benefits are achieved; the problems of low water production rate, short service life, high operation cost and incapability of continuous and stable operation of a reclaimed water recycling membrane system for silicon solar cell wastewater are solved.

Description

Technical Field

[0001] The invention relates to the technical field of silicon solar cell wastewater treatment and resource utilization, in particular to a pretreatment process for water reuse in silicon solar cell wastewater. Background Art

[0002] Under the guidance of the national "dual carbon" strategy, renewable energy has achieved breakthrough development, among which photovoltaic power generation has the strongest growth momentum, driving large-scale expansion of upstream, midstream and downstream enterprises in the photovoltaic industry. As an important intermediate link in the production of photovoltaic cells, the production and manufacturing of silicon solar cells not only consumes a large amount of water resources, but also produces a large amount of wastewater, which has a huge impact on municipal water supply and water ecological environment. Therefore, it is urgent to develop wastewater resource utilization technology to achieve the rational use of wastewater resources. The use of reclaimed water reuse technology can solve these problems. The treated wastewater can be reused in the workshop as recycled water, reducing the amount of wastewater discharge while also reducing the amount of water used at the source.

[0003] The wastewater discharged from silicon solar cells is large, and the pH of the mixed wastewater is low and contains complex ions such as hydrogen peroxide, silicate, calcium, magnesium, aluminum, fluorine, sulfate, chloride, and boron. Since the wastewater contains oxidizing substances, high salt and hardness, it is easy to cause corrosion or blockage of the pipes and equipment of the water reuse membrane system, reduce the equipment operation efficiency and increase the operation and maintenance costs. Therefore, it is necessary to take pretreatment measures for the raw water to improve the water production rate of the membrane system and extend the service life of the membrane. The conventional pretreatment methods of the water reuse membrane system mainly include coagulation and sedimentation method and chemical addition method, but the coagulation and sedimentation method cannot effectively remove difficult-to-precipitate substances such as high hardness and fine particles. In addition, the chemical addition method has the disadvantages of large dosage, low addition efficiency, and high addition cost.

[0004] In recent years, there have been many patents and literature reports on pretreatment methods for reclaimed water reuse systems. For example, Chinese patent application number: CN202122506321.7 proposes a pretreatment device for reclaimed water, which uses a grid + collection + precipitation + dosing combination device. Although it achieves effective removal of large particles and organic matter in wastewater, it does not involve the removal of fine particles, hardness and oxidizing substances. Another example is Chinese patent application number: CN202310471896.0, which uses a secondary softening box + adjustment box pretreatment device, and adds calcium ion de-hardening agent, magnesium ion softener, coagulant, flocculant and bactericide respectively. Although some hardness and fine particles are removed, other cations that can pass through the membrane system and oxidizing substances in the oxidation membrane system cannot be removed efficiently.

[0005] Therefore, developing a pretreatment process suitable for the water reuse membrane system of silicon solar cell wastewater is of great significance and practical value for the resource treatment of silicon solar cell wastewater. Utility Model Content

[0006] In order to solve the problems raised in the above-mentioned background technology, the purpose of the present invention is to provide a pretreatment process for water reuse in silicon solar cell wastewater, which has the ability to carry out targeted graded pretreatment of characteristic pollutants that affect the membrane system for reclaimed water reuse, and provides a new idea for the resource utilization of silicon solar cell wastewater. It has the advantages of significant environmental and economic benefits, and solves the problems of low water production rate, short service life, high operating cost, and inability of the system to operate continuously and stably in the membrane system for water reuse in silicon solar cell wastewater.

[0007] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a pretreatment process for water reuse in silicon solar cell wastewater, comprising a collecting device, wherein the output end of the collecting device is connected to a pretreatment device 1, the output end of the pretreatment device 1 is connected to a pretreatment device 2, the output end of the pretreatment device 2 is connected to a pretreatment device 3, the output end of the pretreatment device 3 is connected to a rear-end reclaimed water reuse membrane system, the feed inlets of the pretreatment devices 1, 2 and 3 are all connected to a pretreatment pH adjustment device at each stage, the interiors of the pretreatment devices 1, 2 and 3 are respectively filled with pretreatment agents 1, 2 and 3, and the pretreatment agents 1, 2 and 3 are used in conjunction with the pretreatment devices 1, 2 and 3, respectively.

[0008] As a preferred embodiment of the present invention, the interior of the pretreatment device 1 is composed of any one of an aeration stirring device, a mechanical stirring device, and a manganese sand filtering device, or a combination of more than one of the above.

[0009] As a preferred embodiment of the present invention, the interior of the pretreatment device 2 is composed of any one of a coagulation sedimentation device, a magnetic coagulation sedimentation device, and a high-density coagulation sedimentation device, or a combination of the above.

[0010] As a preferred embodiment of the present invention, the interior of the pretreatment device 3 is composed of any one or a combination of a coagulation sedimentation device, a magnetic coagulation sedimentation device, a high-density coagulation sedimentation device, and an ion exchange resin device.

[0011] As a preferred embodiment of the present invention, the pH range of each stage of the pretreatment pH adjusting device is 5-13 for pretreatment device 1, 10-13 for pretreatment device 2, and 7-10 for pretreatment device 3.

[0012] As a preferred embodiment of the present invention, the material of the pretreatment agent 1 is any one of sodium bisulfite, sodium pyrosulfite, manganese dioxide, and biological enzyme agent or a combination of the above.

[0013] As a preferred embodiment of the present invention, the material of the pretreatment agent 2 is any one of magnesium sulfate, magnesium chloride, magnesium oxide, and polyaluminium chloride or a combination of the above.

[0014] As a preferred embodiment of the present invention, the material of the pretreatment agent 3 is any one of sodium carbonate, sodium phosphate, and disodium ethylenediaminetetraacetate, or a combination of the above.

[0015] As preferred in the present invention, the water quality requirements of the pretreated water are pH: 5-10, hydrogen peroxide: not detected, silicate: 0-100 mg / L, and hardness: 0-400 mg / L.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention discloses a pretreatment process for a water reuse membrane system of silicon solar cell wastewater. Specifically, it relates to a graded pretreatment method for a water reuse membrane system of silicon solar cell wastewater. This method is widely applicable to the pretreatment of recycled water reuse of silicon solar cell wastewater containing silicon and hydrogen peroxide, and has a broad spectrum.

[0017] 2. The present invention carries out targeted graded pretreatment of characteristic pollutants that affect the reclaimed water reuse membrane system, removes hydrogen peroxide, silicate, and hardness in turn, avoids the decomposition of hydrogen peroxide affecting the sludge settling effect of silicon removal and hardness removal in the later stage, and the hardness introduced by silicon removal is removed by the later stage hardness removal process. The three-stage pretreatment ensures that the effluent meets the water quality requirements of the membrane system, improves the water production rate of the membrane system, and prolongs the service life of the membrane system, which is economical.

[0018] 3. The present invention ensures the stability of the water quality of the membrane system's inlet water through a graded pretreatment process, ensuring that the membrane system can operate stably and efficiently for a long time, which not only reduces the amount of pollution discharged by silicon solar cell manufacturers, but also reduces the consumption of raw water by recycling the water produced by the membrane system to the workshop, thereby improving the reuse rate of water resources and having significant environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 The present invention is a process flow chart of a pretreatment process of a water recycling membrane system in wastewater from silicon solar cell wafers. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] like Figure 1As shown, a pretreatment process for water reuse of silicon solar cell wastewater provided by the present invention comprises a collecting device, the output end of the collecting device is connected with a pretreatment device 1, the output end of the pretreatment device 1 is connected with a pretreatment device 2, the output end of the pretreatment device 2 is connected with a pretreatment device 3, the output end of the pretreatment device 3 is connected with a rear-end reclaimed water reuse membrane system, the feed inlets of the pretreatment devices 1, 2 and 3 are all connected with a pretreatment pH adjustment device at each stage, the interiors of the pretreatment devices 1, 2 and 3 are respectively filled with pretreatment agents 1, 2 and 3, and the pretreatment agents 1, 2 and 3 are used in conjunction with the pretreatment devices 1, 2 and 3, respectively.

[0022] refer to Figure 1 The interior of the pretreatment device 1 is composed of any one or a combination of an aeration stirring device, a mechanical stirring device, and a manganese sand filtering device.

[0023] As a technical optimization scheme of the present invention, a pretreatment device 1 composed of any one or more of an aeration stirring device, a mechanical stirring device, and a manganese sand filtering device can be used to stir and mix weak acid wastewater and weak alkaline wastewater discharged from the production of a silicon solar cell workshop with a pretreatment agent 1, thereby removing hydrogen peroxide from the wastewater.

[0024] refer to Figure 1 The interior of the pretreatment device 2 is composed of any one or a combination of a coagulation sedimentation device, a magnetic coagulation sedimentation device, and a high-density coagulation sedimentation device.

[0025] As a technical optimization scheme of the present invention, a pretreatment device 2 composed of any one or more of a coagulation sedimentation device, a magnetic coagulation sedimentation device, and a high-density coagulation sedimentation device can precipitate the wastewater after preliminary filtration, and the silicate in the wastewater can be removed by adding a pretreatment agent 2.

[0026] refer to Figure 1 The interior of the pretreatment device 3 is composed of any one or a combination of a coagulation sedimentation device, a magnetic coagulation sedimentation device, a high-density coagulation sedimentation device, and an ion exchange resin device.

[0027] As a technical optimization scheme of the present invention, through a pretreatment device 3 composed of any one or more of a coagulation sedimentation device, a magnetic coagulation sedimentation device, a high-density coagulation sedimentation device, and an ion exchange resin device, the precipitated water enters the high-density coagulation sedimentation device in the pretreatment device 3 in turn for secondary sedimentation, and after most of the hardness in the wastewater is removed by the pretreatment agent 3, it is then used in an ion exchange resin device to deeply remove the hardness.

[0028] refer to Figure 1 The pH range of each stage of pretreatment pH adjusting device is 5~13 for pretreatment device 1, 10~13 for pretreatment device 2, and 7~10 for pretreatment device 3.

[0029] As a technical optimization scheme of the present invention, the pH range of each stage of pretreatment pH adjustment device is set as 5-13 for pretreatment device 1, 10-13 for pretreatment device 2, and 7-10 for pretreatment device 3. In order to ensure the normal growth and metabolism of microorganisms during the treatment process and the optimal conditions for chemical reactions, a suitable treatment environment is maintained, thereby improving the treatment effect.

[0030] refer to Figure 1 The material of the pretreatment agent 1 is any one of sodium bisulfite, sodium pyrosulfite, manganese dioxide, and biological enzyme agent or a combination of the above.

[0031] As a technical optimization scheme of the present invention, the pretreatment agent 1 composed of any one or more of sodium bisulfite, sodium pyrosulfite, manganese dioxide, and biological enzyme agents can reduce hydrogen peroxide to water, thereby eliminating its oxidizing property and avoiding its influence on the back-end membrane system.

[0032] refer to Figure 1 The material of the pretreatment agent 2 is any one of magnesium sulfate, magnesium chloride, magnesium oxide, and polyaluminium chloride or a combination of the above.

[0033] As a technical optimization scheme of the present invention, the pretreatment agent 2 composed of any one or more of magnesium sulfate, magnesium chloride, magnesium oxide, and polyaluminium chloride can form an insoluble precipitate with silicate through a chemical reaction, thereby effectively removing silicate from the water body. This reaction is usually carried out in an alkaline environment. By adding an appropriate amount of these chemicals, a precipitate can be formed, and then the silicate can be separated from the water by flocculation and precipitation.

[0034] refer to Figure 1 The material of the pretreatment agent 3 is any one of sodium carbonate, sodium phosphate, and disodium ethylenediaminetetraacetate or a combination of the above.

[0035] As a technical optimization scheme of the present invention, the pretreatment agent 3 is formed by a combination of any one or more of sodium carbonate, sodium phosphate, and disodium ethylenediaminetetraacetate. Disodium ethylenediaminetetraacetate can chelate metal ions in the solution, thereby reducing the hardness of the wastewater, while sodium carbonate and sodium phosphate indirectly affect the solubility and existence form of calcium and magnesium ions in the water by adjusting the pH value of the water, thereby reducing the hardness of the water.

[0036] refer to Figure 1 The water quality requirements for pretreated water are pH: 5~10, hydrogen peroxide: not detected, silicate: 0~100mg / L, hardness: 0~400mg / L.

[0037] As a technical optimization scheme of the present invention, the water quality requirements of the pre-treated effluent are set as pH: 5~10, hydrogen peroxide: not detected, silicate: 0~100mg / L, and hardness: 0~400mg / L, which can meet the inlet water quality requirements of the back-end reclaimed water reuse membrane system.

[0038] The working principle and use process of the present invention are as follows: the wastewater of silicon solar cell sheets is any one or more of weak acid wastewater, weak alkaline wastewater discharged from workshop production, and the qualified effluent treated by the wastewater station. After being stored by a collecting device, the pH is first adjusted to 7 and enters the aeration stirring device in the pretreatment device 1, and the sodium bisulfite and biological enzyme agent in the pretreatment agent 1 are added to remove hydrogen peroxide. Then the effluent is adjusted to pH 10 and enters the magnetic coagulation sedimentation device in the pretreatment device 2, and magnesium oxide and polyaluminium chloride in the pretreatment agent 2 are added to remove silicate. Then the precipitated effluent enters the high-density coagulation sedimentation device and the ion exchange resin device in the pretreatment device 3 in turn. After sodium carbonate in the pretreatment agent 3 is added to the high-density coagulation sedimentation device to remove most of the hardness, the ion exchange resin device is further entered to deeply remove the hardness. The effluent indicators of the three-stage pretreatment are pH: 9, hydrogen peroxide: not detected, silicate: 20 mg / L, and hardness: 50 mg / L, thereby meeting the inlet water quality requirements of the back-end reclaimed water reuse membrane system.

[0039] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0040] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pretreatment process for water reuse in silicon solar cell wastewater, comprising a collection device, characterized in that: The output end of the collecting device is connected to the pretreatment device 1, the output end of the pretreatment device 1 is connected to the pretreatment device 2, the output end of the pretreatment device 2 is connected to the pretreatment device 3, the output end of the pretreatment device 3 is connected to the rear-end reclaimed water reuse membrane system, the feed ports of the pretreatment devices 1, 2 and 3 are all connected to each stage of pretreatment PH adjustment device, the interiors of the pretreatment devices 1, 2 and 3 are respectively filled with pretreatment agents 1, 2 and 3, and the pretreatment agents 1, 2 and 3 are used in conjunction with the pretreatment devices 1, 2 and 3, respectively.

2. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The interior of the pretreatment device 1 is composed of any one of an aeration stirring device, a mechanical stirring device, and a manganese sand filtering device or a combination of the above.

3. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The interior of the pretreatment device 2 is composed of any one of a coagulation sedimentation device, a magnetic coagulation sedimentation device, and a high-density coagulation sedimentation device, or a combination of the above.

4. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The interior of the pretreatment device 3 is composed of any one of a coagulation sedimentation device, a magnetic coagulation sedimentation device, a high-density coagulation sedimentation device, and an ion exchange resin device, or a combination of the above.

5. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The pH range of each stage of the pretreatment pH adjusting device is 5-13 for pretreatment device 1, 10-13 for pretreatment device 2, and 7-10 for pretreatment device 3.

6. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The material of the pretreatment agent 1 is any one of sodium bisulfite, sodium pyrosulfite, manganese dioxide, and biological enzymes, or a combination of the above.

7. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The material of the pretreatment agent 2 is any one of magnesium sulfate, magnesium chloride, magnesium oxide, and polyaluminium chloride or a combination thereof.

8. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The material of the pretreatment agent 3 is any one of sodium carbonate, sodium phosphate, and disodium ethylenediaminetetraacetate or a combination of the above.

9. The pretreatment process for water reuse in silicon solar cell wastewater according to claim 1, characterized in that: The water quality requirements of the pretreated water are pH: 5~10, hydrogen peroxide: not detected, silicate: 0~100 mg / L, hardness: 0~400 mg / L.

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