Wastewater treatment system and method

Abstract

The present application relates to wastewater treatment technical field, disclose a kind of wastewater treatment system and method, the wastewater treatment system includes: liquid waste treatment subsystem, can form solid waste and fine wastewater;And solid waste treatment subsystem, can form concentrated liquid and building material. Waste water is first formed by pretreatment coarse waste water, a part of coarse waste water is concentrated to form concentrated liquid, another part of coarse waste water is finely processed to form solid waste and fine waste water, concentrated liquid is mixed with solid waste and is aggregated to form mixture, the mixture is shaped, and building material capable of secondary utilization is obtained. The system and method treat solid waste in wastewater to form building material, so that solid waste can be reused, instead of the way of disposing solid waste as garbage, reduce the possibility of secondary pollution of solid waste to atmosphere, water body, soil.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and more specifically to a wastewater treatment system and method. Background Technology

[0002] Water resources are a key resource affecting the development of human society. In order to reduce the waste of water resources, it is necessary to treat industrial wastewater, such as wastewater from coal-fired power plants. The purpose of wastewater treatment is to separate pollutants in wastewater by some method or decompose them into harmless and stable substances, thereby purifying the wastewater. Generally, it is necessary to meet the requirements of preventing the spread of toxins and germs and avoiding visible objects with unpleasant odors and unpleasant smells.

[0003] Solid waste is also generated during the wastewater treatment process. In the prior art known to the inventor, some of the solid waste generated during the treatment of wastewater from coal-fired power plants is disposed of as garbage, that is, through landfill, ash storage ponds, open-air storage, etc. This treatment method is prone to causing secondary pollution to the atmosphere, water bodies, and soil. Summary of the Invention

[0004] The purpose of this invention is to overcome the problem of secondary pollution caused by the disposal of solid waste as garbage in the existing wastewater treatment process, and to provide a wastewater treatment system and method that can treat solid waste and reduce the possibility of secondary pollution from solid waste.

[0005] To achieve the above objectives, a first aspect of the present invention provides a wastewater treatment system, comprising: a liquid waste treatment subsystem, the liquid waste treatment subsystem including a filtration unit, a grit chamber, and a fine treatment unit connected in sequence, wherein the filtration unit is configured to filter particulate impurities in the wastewater, the grit chamber is configured to settle sand from the wastewater from the filtration unit and form coarse wastewater, the grit chamber having a first outlet and a second outlet for discharging the coarse wastewater, the first outlet of the grit chamber being connected to the inlet of the fine treatment unit, and the fine treatment unit being configured to treat the coarse wastewater entering therein to form solid waste and fine wastewater; and a solid waste treatment subsystem, the solid waste treatment subsystem including a concentrator, a mixer, and a molding machine connected in sequence, the inlet of the concentrator being connected to the second outlet of the grit chamber, the concentrator being configured to concentrate the coarse wastewater entering therein to form a concentrated liquid, the mixer being configured to mix the concentrated liquid from the concentrator with the solid waste from the fine treatment unit and polymerize it to form a mixture, and the molding machine being configured to solidify the mixture from the mixer to form a reusable building material.

[0006] Preferably, the solid waste treatment subsystem also includes a curing chamber, the entrance of which is connected to the outlet of the molding machine, and the curing chamber is capable of storing building materials.

[0007] Preferably, the filtration unit includes a coarse screen tank and a fine screen tank connected sequentially along the wastewater flow direction. The coarse screen tank is equipped with a coarse screen, and the fine screen tank is equipped with a fine screen. The gap between the bars of the coarse screen is larger than the gap between the bars of the fine screen.

[0008] Preferably, the spacing between the bars of the coarse grid is 16mm to 25mm; and / or, the spacing between the bars of the fine grid is 1.5mm to 10mm.

[0009] Preferably, the fine treatment unit includes a primary sedimentation tank, an aeration tank, an oxidation reaction tank, and a secondary sedimentation tank connected in sequence. The secondary sedimentation tank has a solid waste outlet, which is connected to the solid waste inlet of the mixing machine.

[0010] Preferably, the liquid waste treatment subsystem further includes a flocculation tank, a filter, and a disinfection tank connected in sequence. The secondary sedimentation tank also has a liquid waste outlet. The inlet of the flocculation tank is connected to the liquid waste outlet of the secondary sedimentation tank. The flocculation tank can oxidize and degrade harmful substances in the fine wastewater from the secondary sedimentation tank. The filter can filter the fine wastewater from the flocculation tank. The disinfection tank can disinfect the fine wastewater from the filter and form qualified water that can be discharged.

[0011] The second aspect of the present invention provides a wastewater treatment method, comprising the following steps: pretreating wastewater to obtain coarse wastewater; concentrating a portion of the coarse wastewater to obtain a concentrate; further treating another portion of the coarse wastewater to obtain solid waste and fine wastewater; mixing the concentrate and solid waste and polymerizing them to form a mixture; and molding the mixture to obtain a building material that can be reused.

[0012] Preferably, the wastewater treatment method further includes storing building materials.

[0013] Preferably, the pretreatment step of the wastewater specifically includes: after the wastewater is subjected to coarse filtration and fine filtration in sequence, the sand and gravel in the wastewater are settled to obtain coarse wastewater; and / or, the fine treatment step of another part of the coarse wastewater specifically includes: after the other part of the coarse wastewater is subjected to primary sedimentation, aeration, oxidation and secondary sedimentation in sequence, solid waste and fine wastewater are obtained.

[0014] Preferably, the wastewater treatment method employs the wastewater treatment system described above.

[0015] The above technical solution involves pre-treating wastewater to form coarse wastewater, concentrating a portion of the coarse wastewater to form a concentrated liquid, and further treating the remaining coarse wastewater to form solid waste and fine wastewater. The concentrated liquid and solid waste are mixed and polymerized to form a mixture, which is then molded to obtain reusable building materials. This system and method treat solid waste from wastewater to form building materials, enabling the reuse of solid waste and replacing the method of disposing of solid waste as garbage, thus reducing the possibility of secondary pollution of the atmosphere, water bodies, and soil by solid waste. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the wastewater treatment system structure of the present invention; and

[0017] Figure 2 This is a schematic diagram of another form of the wastewater treatment system of the present invention.

[0018] Explanation of reference numerals in the attached figures

[0019] 1. Coarse screen tank; 2. Fine screen tank; 3. Grit chamber; 4. Primary sedimentation tank; 5. Aeration tank; 6. Oxidation reaction tank; 7. Secondary sedimentation tank; 8. Flocculation tank; 9. Filter; 10. Disinfection tank; 11. Concentrator; 12. Mixer; 13. Molding machine; 14. Curing room; 100. Liquid waste treatment subsystem; 101. Filtration unit; 102. Fine treatment unit; 200. Solid waste treatment subsystem. Detailed Implementation

[0020] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.

[0021] See Figure 1 and Figure 2 As shown, the present invention provides a wastewater treatment system, including: a liquid waste treatment subsystem 100, which includes a filtration unit 101, a grit chamber 3, and a fine treatment unit 102 connected in sequence. The filtration unit 101 is configured to filter particulate impurities in the wastewater, and the grit chamber 3 is configured to settle sand from the wastewater from the filtration unit 101 to form coarse wastewater. The grit chamber 3 has a first outlet and a second outlet for discharging the coarse wastewater. The first outlet of the grit chamber 3 is connected to the inlet of the fine treatment unit 102, which is configured to discharge the coarse wastewater into the fine treatment unit 102. The system treats coarse wastewater to form solid waste and fine wastewater; and includes a solid waste treatment subsystem 200, which includes a concentrator 11, a mixer 12, and a molding machine 13 connected in sequence. The inlet of the concentrator 11 is connected to the second outlet of the grit chamber 3. The concentrator 11 is configured to concentrate the coarse wastewater entering it to form a concentrated liquid. The mixer 12 is configured to mix and polymerize the concentrated liquid from the concentrator 11 with the solid waste from the fine waste treatment unit 102 to form a mixture. The molding machine 13 is configured to solidify the mixture from the mixer 12 to form a building material that can be reused.

[0022] In this embodiment, the wastewater is first pretreated through the filtration unit 101 and the grit chamber 3 to form coarse wastewater. The filtration unit 101 and the grit chamber 3 remove particulate impurities and sand from the wastewater through physical filtration. The coarse wastewater is divided into two parts: one part enters the fine treatment unit 102, and the other part enters the concentrator 11 of the solid waste treatment subsystem 200. The coarse wastewater entering the fine treatment unit 102 is further treated to form solid waste and fine wastewater. The solid waste mainly consists of sludge and settled suspended solids. The coarse wastewater entering the concentrator 11 is concentrated, mainly to form a concentrated liquid, which is then fed into the mixer 12 along with the solid waste. An inorganic polymerizing agent is added to the mixer 12. Figure 1 or Figure 2 (The broken arrow on the right side of the mixing mill 12 is shown in the diagram). Utilizing the chemical bonding and adsorption of pollutants and salts by inorganic polymers, as well as the physical barrier effect of the inorganic polymer cage structure, a low-permeability, high-strength inorganic polymer solid is generated. This solid directly solidifies and encapsulates the pollutants and salts. The inorganic polymer solid is a mixture of solid waste and concentrated liquid. Through different component ratios, it is then molded by the molding machine 13 into various environmentally acceptable building materials, such as curb stones and sidewalk bricks. These materials can be used as raw materials for curb stone and sidewalk brick production, or as fillers for roads and buildings, thus achieving resource utilization through waste treatment and wastewater resource recovery. The combination of solid waste and concentrated liquid forms reusable building materials. This system allows solid waste to be treated and reused, replacing the existing method of treating solid waste as garbage, and reducing the possibility of secondary pollution of the atmosphere, water bodies, and soil.

[0023] Specifically, the wastewater treated by this wastewater treatment system is wastewater generated by coal-fired power plants. This wastewater has a high salt content and also contains chlorine, calcium, magnesium, and heavy metals. The solid waste contains coal ash, slag, and other substances.

[0024] It should be noted that building materials need to be tested before they are put into use. Only when the building materials meet the condition that they will no longer cause secondary pollution can they be reused.

[0025] See Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the solid waste treatment subsystem 200 further includes a curing chamber 14, the inlet of which is connected to the outlet of the molding machine 13, and the curing chamber 14 is capable of storing building materials.

[0026] In this embodiment, the curing chamber 14 is used to store the molded building materials, providing them with storage space and preventing them from being affected by the external environment and rendered unusable. When the building materials are needed, they are taken out of the curing chamber 14.

[0027] See Figure 1 and Figure 2As shown, in one embodiment of the present invention, the filtration unit 101 includes a coarse screen tank 1 and a fine screen tank 2 connected sequentially along the wastewater flow direction. The coarse screen tank 1 is provided with a coarse screen, and the fine screen tank 2 is provided with a fine screen. The gap between the bars of the coarse screen is larger than the gap between the bars of the fine screen.

[0028] In this embodiment, wastewater enters the coarse screen tank 1, passing through the coarse screen. Large-diameter particulate impurities in the wastewater are intercepted by the coarse screen and remain in the coarse screen tank 1 for subsequent cleaning. The wastewater continues into the fine screen tank 2, passing through the fine screen. Small-diameter particulate impurities in the wastewater are intercepted by the fine screen and remain in the fine screen tank 2 for subsequent cleaning. The wastewater continues into the grit chamber 3, where sand in the wastewater settles and remains in the grit chamber 3. The water in the upper layer of the grit chamber 3 forms coarse wastewater, and the sand particle size is smaller than that of the small-diameter particulate impurities. The coarse screen tank 1 and the fine screen tank 2 filter particulate impurities of different sizes through the different gaps between the screen bars. Combined with the grit chamber 3, a gradient physical filtration of the wastewater is achieved, removing as many particulate impurities and sand as possible from the wastewater.

[0029] See Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the spacing between the bars of the coarse grid is 16mm to 25mm; the spacing between the bars of the fine grid is 1.5mm to 10mm.

[0030] In this embodiment, particulate impurities with a minimum size greater than 16mm to 25mm in the wastewater are classified as large-diameter impurities. The coarse screen is specifically used to filter large-diameter particulate impurities, and the number of large-diameter particulate impurities intercepted by the coarse screen is moderate. Particulate impurities with a minimum size greater than 1.5mm to 10mm are classified as small-diameter impurities, and the fine screen is specifically used to filter small-diameter particulate impurities, and the number of small-diameter particulate impurities intercepted by the fine screen is also moderate. The combination of coarse screen tank 1 and fine screen tank 2 achieves gradient physical filtration, avoiding excessive particulate impurities in a single filtration that could cause the screen bars to clog, thereby avoiding affecting the filtration efficiency.

[0031] See Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the fine treatment unit 102 includes a primary sedimentation tank 4, an aeration tank 5, an oxidation reaction tank 6 and a secondary sedimentation tank 7 connected in sequence. The secondary sedimentation tank 7 has a solid waste outlet, and the solid waste outlet of the secondary sedimentation tank 7 is connected to the solid waste inlet of the mixer 12.

[0032] In this embodiment, the primary sedimentation tank 4 removes fine suspended solids from the coarse wastewater entering it through overflow; the aeration tank 5 aerates the coarse wastewater treated by the primary sedimentation tank 4, and the aeration tank 5 is equipped with an aerator that stirs the coarse wastewater in the aeration tank 5, decomposing the organic matter that may cause pollution in the coarse wastewater and reducing the concentration of such organic matter in the coarse wastewater; the oxidation reaction tank 6 oxidizes the coarse wastewater treated by the aeration tank 5, adsorbing the fine particulate matter in the coarse wastewater, that is, the coarse wastewater... Fine particulate matter is removed from the water. The secondary sedimentation tank 7 further settles the coarse wastewater after treatment in the oxidation reaction tank 6, separating the solids and liquids and removing sludge, activated sludge, and other substances. The sludge-water separation in the secondary sedimentation tank 7, combined with the aeration tank 5 and oxidation reaction tank 6, provides contact oxidation and aeration treatment to the coarse wastewater, effectively reducing its toxicity. After solid-liquid separation in the secondary sedimentation tank 7, the coarse wastewater forms fine wastewater and solid waste. The fine wastewater continues to be treated in subsequent treatment equipment. The solid waste after the fine treatment unit 102 is free of pollutants or its pollutant content meets requirements. Further treatment of the solid waste ensures that the final building materials will not cause secondary pollution.

[0033] See Figure 1 and Figure 2 As shown, in one embodiment of the present invention, the liquid waste treatment subsystem 100 further includes a flocculation tank 8, a filter 9, and a disinfection tank 10 connected in sequence. The secondary sedimentation tank 7 also has a liquid waste outlet. The inlet of the flocculation tank 8 is connected to the liquid waste outlet of the secondary sedimentation tank 7. The flocculation tank 8 can oxidize and degrade harmful substances in the fine wastewater from the secondary sedimentation tank 7. The filter 9 can filter the fine wastewater from the flocculation tank 8. The disinfection tank 10 can disinfect the fine wastewater from the filter 9 and form qualified water that can be discharged.

[0034] In this embodiment, the fine wastewater treated in the secondary sedimentation tank 7 enters the flocculation tank 8, and a flocculant is added to the flocculation tank 8. Figure 1 or Figure 2The vertical downward arrow between the secondary sedimentation tank 7 and the flocculation tank 8 indicates that the secondary sedimentation tank 7 degrades harmful substances such as colloids and fine suspended solids in the fine wastewater, and then, after coagulation and sedimentation, performs cement separation. The filter 9 adsorbs and filters the fine wastewater treated by the flocculation tank 8, intercepting fine solids in the wastewater through physical filtration. The disinfection tank 10 disinfects the fine wastewater treated by the filter 9, eliminating bacteria and other toxic substances in the wastewater, forming qualified water that meets discharge standards and will not cause pollution or harm to the environment. It can also be used as recycled water for production. The flocculation tank 8, filter 9, and disinfection tank 10 are used to further treat the fine wastewater, ensuring that it meets discharge requirements and avoiding pollution from both solid and liquid waste. This system offers low cost, high efficiency, and stable performance in wastewater treatment.

[0035] Specifically, filter 9 is a porous carbon filter 9; disinfection tank 10 is an ultraviolet disinfection tank 10. The flocculant is a composite flocculant.

[0036] The second aspect of the present invention provides a wastewater treatment method, comprising the following steps: pretreating wastewater to obtain coarse wastewater; concentrating a portion of the coarse wastewater to obtain a concentrate; further treating another portion of the coarse wastewater to obtain solid waste and fine wastewater; mixing the concentrate and solid waste and polymerizing them to form a mixture; and molding the mixture to obtain a building material that can be reused.

[0037] In this embodiment, pretreatment removes particulate impurities and sand from the wastewater through physical filtration, yielding coarse wastewater. This coarse wastewater is divided into two parts: one part is concentrated to form a concentrate, which is used to mix with solid waste; the other part undergoes further fine treatment to obtain fine wastewater and solid waste. The mixture can be processed into building materials, enabling the solid waste to be reused, replacing the existing method of treating solid waste as garbage, and reducing the possibility of secondary pollution of the atmosphere, water bodies, and soil.

[0038] In one embodiment of the present invention, the wastewater treatment method further includes: storing building materials.

[0039] In this embodiment, the stored building materials are isolated from the outside world to prevent the external environment from affecting the building materials.

[0040] In one embodiment of the present invention, the pretreatment step of wastewater specifically includes: subjecting the wastewater to coarse filtration and fine filtration in sequence, and then settling the sand and gravel in the wastewater to obtain coarse wastewater.

[0041] In this embodiment, the wastewater undergoes gradient physical filtration, where large-diameter particulate impurities, small-diameter particulate impurities, and even smaller-diameter sand are filtered out sequentially. This gradient filtration method ensures that particulate impurities and sand in the wastewater are removed as completely as possible, while also preventing the filtration efficiency from being affected by removing too many particulate impurities and sand at once.

[0042] In one embodiment of the present invention, the step of further treating another portion of the coarse wastewater specifically includes: subjecting the other portion of the coarse wastewater to a first sedimentation, aeration, oxidation, and a second sedimentation in sequence to obtain solid waste and fine wastewater.

[0043] In this embodiment, fine suspended solids in the coarse wastewater are removed through primary sedimentation; aeration is used to stir the coarse wastewater and decompose the polluting organic matter in the coarse wastewater, reducing the concentration of polluting organic matter in the coarse wastewater; oxidation is used to treat the coarse wastewater and adsorb the fine particulate matter in the coarse wastewater, thereby removing the fine particulate matter in the coarse wastewater; and secondary sedimentation is used to separate the solid and liquid in the coarse wastewater, removing substances such as mud and activated sludge from the coarse wastewater.

[0044] Specifically, the fine wastewater undergoes flocculation, filtration, and disinfection to obtain qualified water that meets discharge requirements. This process treats solid waste to prevent pollution of the environment, while also preventing pollution of the environment by liquid waste, and allows the qualified water to be reused as production water.

[0045] Please see Figure 1 and Figure 2 In another embodiment of the present invention, the wastewater treatment method uses the above-described wastewater treatment system and specifically includes the following steps:

[0046] S1. Large-diameter particulate impurities and small-diameter particulate impurities in the wastewater are filtered and removed sequentially through coarse screen tank 1 and fine screen tank 2.

[0047] S2. The wastewater treated by coarse screen tank 1 and fine screen tank 2 is introduced into grit chamber 3. The grit in the wastewater is removed by sedimentation in grit chamber 3 to obtain coarse wastewater.

[0048] S3. A portion of the coarse wastewater is introduced into the concentrator 11 for concentration, resulting in a concentrated liquid. This concentrated liquid is then introduced into the mixer 12. Another portion of the coarse wastewater is introduced into the primary sedimentation tank 4. The overflow from the primary sedimentation tank 4 removes fine suspended solids from the coarse wastewater. The treated coarse wastewater from the primary sedimentation tank 4 is then introduced into the aeration tank 5, where it is aerated for 50 minutes and then allowed to stand for 40 minutes. Through the aeration and stirring action of the aeration tank 5, the organic matter that may cause pollution in the coarse wastewater is decomposed, reducing the amount of pollutants. The concentration of polluted organic matter is determined by introducing the coarse wastewater treated in aeration tank 5 into oxidation reaction tank 6. Through the curing effect of oxidation reaction tank 6, fine particulate matter in the coarse wastewater is adsorbed. The coarse wastewater treated in oxidation reaction tank 6 is then introduced into secondary sedimentation tank 7, where it stays for 0.5h to 2h. Through the sedimentation effect of secondary sedimentation tank 7, solid-liquid separation is performed on the coarse wastewater, removing sludge, activated sludge and other substances from the coarse wastewater, resulting in fine wastewater and solid waste. The fine wastewater is then introduced into flocculation tank 8, and the solid waste is introduced into mixing machine 12.

[0049] S4. Add an inorganic polymerizing agent to the mixer 12. Mix and polymerize the concentrate and solid waste through the mixer 12. Utilize the chemical binding and adsorption of pollutants and salts by the inorganic polymerizing agent and the physical barrier effect of the inorganic polymer cage structure to generate a low-permeability, high-strength inorganic polymer solid. This directly solidifies and encapsulates pollutants and salts. The inorganic polymer solid is the mixture. Introduce the mixture into the molding machine 13 to form a building material that can be reused. Store the building material in the curing room 14.

[0050] S5. Add a composite flocculant to the flocculation tank 8. The amount of flocculant added is 0.01% to 0.05% of the amount of wastewater entering the flocculation tank 8. This degrades harmful substances such as colloids and fine suspended solids in the fine wastewater. After coagulation and sedimentation, cement separation is performed. The fine wastewater treated by the flocculation tank 8 is introduced into the filter 9. Through the adsorption and filtration effect of the filter 9, the fine solids in the fine wastewater are adsorbed and intercepted. The fine wastewater treated by the filter 9 is then introduced into the disinfection tank 10. Through the disinfection effect of the disinfection tank 10, bacteria and other toxic substances in the fine wastewater are eliminated, forming qualified water that meets the discharge requirements.

[0051] Steps S4 and S5 can be performed simultaneously.

[0052] It should be noted that existing wastewater treatment processes, such as the patent application number 201710912221.X, disclose a paint spraying wastewater treatment process. In the wastewater treatment process, multiple agents such as neutralizing agents, demulsifiers, anaerobic bacteria, potassium permanganate, and polyethylene solution need to be added. Compared with this prior art, this wastewater treatment system and method do not require the addition of too many agents during the wastewater treatment process, and will not cause secondary pollution to the environment due to agent residues, so that the treated solid waste can meet the requirements for reuse.

[0053] The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various specific technical features in any suitable manner. To avoid unnecessary repetition, the present invention will not describe the various possible combinations separately. However, these simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A wastewater treatment system, characterized in that, include: A liquid waste treatment subsystem (100) includes a filtration unit (101), a grit chamber (3), and a fine treatment unit (102) connected in sequence. The filtration unit (101) is configured to filter particulate impurities in wastewater. The grit chamber (3) is configured to settle sand from the wastewater from the filtration unit (101) and form coarse wastewater. The grit chamber (3) has a first outlet and a second outlet for discharging the coarse wastewater. The first outlet of the grit chamber (3) is connected to the inlet of the fine treatment unit (102). The fine treatment unit (102) is configured to treat the coarse wastewater entering it to form solid waste and fine wastewater. A solid waste treatment subsystem (200) includes a concentrator (11), a mixer (12), and a molding machine (13) connected in sequence. The inlet of the concentrator (11) is connected to the second outlet of the grit chamber (3). The concentrator (11) is configured to concentrate the coarse wastewater entering it into a concentrated liquid. The mixer (12) is configured to mix and polymerize the concentrated liquid from the concentrator (11) with the solid waste from the fine treatment unit (102) to form a mixture. The molding machine (13) is configured to solidify the mixture from the mixer (12) into a building material that can be reused. The fine treatment unit (102) includes a primary sedimentation tank (4), an aeration tank (5), an oxidation reaction tank (6), and a secondary sedimentation tank (7) connected in sequence. The secondary sedimentation tank (7) has a solid waste outlet, and the solid waste outlet of the secondary sedimentation tank (7) is connected to the solid waste inlet of the mixer (12). The liquid waste treatment subsystem (100) also includes a flocculation tank (8), a filter (9) and a disinfection tank (10) connected in sequence. The secondary sedimentation tank (7) also has a liquid waste outlet. The inlet of the flocculation tank (8) is connected to the liquid waste outlet of the secondary sedimentation tank (7). The wastewater is generated by a coal-fired power plant, and the solid waste contains coal ash and slag.

2. The wastewater treatment system according to claim 1, characterized in that, The solid waste treatment subsystem (200) also includes a curing chamber (14), the entrance of which is connected to the outlet of the molding machine (13), and the curing chamber (14) is capable of storing the building materials.

3. The wastewater treatment system according to claim 1, characterized in that, The filtration unit (101) includes a coarse screen tank (1) and a fine screen tank (2) connected sequentially along the wastewater flow direction. The coarse screen tank (1) is provided with a coarse screen, and the fine screen tank (2) is provided with a fine screen. The gap between the bars of the coarse screen is larger than the gap between the bars of the fine screen.

4. The wastewater treatment system according to claim 3, characterized in that, The spacing between the bars of the coarse grid is 16mm to 25mm; and / or the spacing between the bars of the fine grid is 1.5mm to 10mm.

5. A wastewater treatment method, characterized in that, The wastewater treatment method is carried out using the wastewater treatment system according to any one of claims 1 to 4, and includes the following steps: pretreating the wastewater to obtain coarse wastewater; concentrating a portion of the coarse wastewater to obtain a concentrated liquid; further treating another portion of the coarse wastewater to obtain solid waste and fine wastewater; mixing the concentrated liquid and the solid waste and polymerizing them to form a mixture; molding the mixture to obtain building materials that can be reused.

6. The wastewater treatment method according to claim 5, characterized in that, The wastewater treatment method further includes storing the building materials.

7. The wastewater treatment method according to claim 5, characterized in that, The steps for pretreating the wastewater specifically include: subjecting the wastewater to coarse filtration and fine filtration in sequence, and then settling the sand and gravel in the wastewater to obtain coarse wastewater; and / or, the steps for fine treatment of another part of the coarse wastewater specifically include: subjecting the other part of the coarse wastewater to primary sedimentation, aeration, oxidation and secondary sedimentation in sequence to obtain solid waste and fine wastewater.

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