A pretreatment system for water reuse

Abstract

The utility model relates to a kind of pretreatment system of reclaimed water, including hard-removal mechanism, depth processing mechanism, aeration homogenate pool, manganese sand filter tank, sand filter water tank, integrated membrane processing unit and reuse water pool;Hard-removal mechanism, depth processing mechanism, aeration homogenate pool, manganese sand filter tank, sand filter water tank, integrated membrane processing unit and reuse water pool are sequentially communicated by pipeline in order;Hard-removal mechanism is used to remove calcium, magnesium ion in workshop tail water;Depth processing mechanism is used for depth processing pollutant in water;Integrated membrane processing unit is used to remove suspended, colloidal material in water.The water that entire process meets production reuse standard after system processing is stored in reuse water pool, and the water of reuse water pool can be used as papermaking workshop water supply (such as boiler water etc.), water is recycled, water is saved.Simplify process flow, remove redundant unit, save land area, and first end removes hard, improve the service life of integrated membrane processing unit.

Description

Technical Field

[0001] This utility model relates to the field of papermaking wastewater treatment technology, specifically to a pretreatment system for recycled water. Background Technology

[0002] In the process of papermaking wastewater treatment, the pretreatment process of recycled water is a key link to ensure the efficiency of subsequent deep treatment and extend the service life of equipment. The core objective is to remove suspended solids, colloids, floating matter, some organic matter and microorganisms from the raw water, and reduce the pollution load of water quality on subsequent treatment units (such as membrane filtration and disinfection).

[0003] Current pretreatment processes for reclaimed water reuse are lengthy, involve numerous unit operations, require large land areas, and incur high infrastructure and operating costs. Mechanically accelerated clarifiers have poor hardness removal efficiency, leading to scaling in subsequent membrane systems (ultrafiltration, reverse osmosis), frequent cleaning, and short membrane lifespan. Backwash water is not treated and reused, resulting in low water resource utilization and high operating costs. Utility Model Content

[0004] Therefore, a pretreatment system for reclaimed water reuse is needed to address the current pretreatment processes for reclaimed water reuse, which are characterized by lengthy processes, numerous unit operations, large footprint, and high infrastructure and operating costs. Mechanically accelerated clarifiers have poor hardness removal efficiency, leading to scaling, frequent cleaning, and short membrane lifespan in subsequent membrane systems (ultrafiltration, reverse osmosis). Furthermore, backwash water is not treated and reused, resulting in low water resource utilization and high operating costs.

[0005] To achieve the above objectives, the inventors provide a pretreatment system for recycled water, including a hardening removal mechanism, a deep treatment mechanism, an aeration homogenizing tank, a manganese sand filter, a sand filter permeate tank, an integrated membrane treatment unit, and a recycled water tank.

[0006] The hardening removal mechanism, the deep treatment mechanism, the aeration homogenizing tank, the manganese sand filter, the sand filter permeate tank, the integrated membrane treatment unit, and the recycled water tank are connected in sequence through pipelines.

[0007] The hardness removal mechanism is used to remove calcium and magnesium ions from the workshop effluent;

[0008] The advanced treatment unit is used for the advanced treatment of pollutants in the water;

[0009] The integrated membrane treatment unit is used to remove suspended and colloidal substances from water.

[0010] As a preferred structure of this utility model, the deep treatment mechanism includes a coagulation reaction tank, a coagulation sedimentation tank, a Fenton reaction tank, a transfer tank, and a cooling tower.

[0011] The coagulation reaction tank is connected to the hardening removal mechanism via a pipeline;

[0012] The coagulation reaction tank, the coagulation sedimentation tank, the Fenton reaction tank, the transfer tank, and the cooling tower are connected in sequence via pipelines.

[0013] The cooling tower and the aeration homogenizing tank are connected by pipelines.

[0014] As a preferred structure of this utility model, the integrated membrane treatment unit includes an ultrafiltration mechanism, an ultrafiltration permeate tank, a reverse osmosis mechanism, and a reverse osmosis permeate tank.

[0015] The ultrafiltration unit is connected to the sand filter water production tank via a pipeline;

[0016] The ultrafiltration unit, the ultrafiltration product water tank, the reverse osmosis unit, and the reverse osmosis product water tank are connected in sequence through pipelines.

[0017] The reverse osmosis permeate tank and the recycled water tank are connected by pipelines.

[0018] As a preferred structure of this utility model, the reverse osmosis mechanism includes a multi-stage reverse osmosis membrane, and there are multiple reverse osmosis product water tanks;

[0019] The reverse osmosis membranes are connected to the reverse osmosis permeate tanks via pipelines, and the multiple reverse osmosis membranes correspond to multiple reverse osmosis permeate tanks.

[0020] As a preferred structure of this utility model, the pretreatment system for recycled water also includes a filtration mechanism, which is installed on the pipeline between the sand filter water production tank and the ultrafiltration mechanism, and is used to filter fine suspended solids in the water.

[0021] As a preferred structure of this utility model, the pretreatment system for recycled water also includes a concentrate tank, which is connected to the reverse osmosis unit via a pipeline.

[0022] As a preferred embodiment of this invention, the pretreatment system for recycled water further includes an electro-deionization device, which is installed on the pipeline between the reverse osmosis permeate tank and the recycled water tank. The electro-deionization device is used to remove impurities from the water to deeply purify the water quality.

[0023] As a preferred structure of this utility model, the pretreatment system for recycled water further includes a backwash wastewater collection tank, the manganese sand filter is connected to the backwash wastewater collection tank through a pipeline, the filtration mechanism is connected to the backwash wastewater collection tank through a pipeline, and the ultrafiltration mechanism is connected to the backwash wastewater collection tank through a pipeline.

[0024] As a preferred structure of this utility model, the pretreatment system for recycled water further includes a sedimentation tank, which is connected to the backwash wastewater collection tank via a pipeline, and the supernatant of the sedimentation tank is connected to the aeration homogenizing tank via a pipeline.

[0025] As a preferred embodiment of this utility model, the pretreatment system for greywater reuse further includes an intermediate water tank and a first lift pump. The intermediate water tank is connected to the hardening removal mechanism via a pipeline, and the first lift pump is installed on the pipeline between the intermediate water tank and the hardening removal mechanism; or

[0026] The pretreatment system for recycled water also includes an intermediate water tank, a first lift pump, an emergency tank, and a second lift pump. The intermediate water tank is connected to the hardening removal mechanism via a pipeline, and the first lift pump is installed on the pipeline between the intermediate water tank and the hardening removal mechanism. The emergency tank is connected to the intermediate water tank via a pipeline, and the emergency tank is connected to the hardening removal mechanism via a pipeline. The second lift pump is installed on the pipeline between the emergency tank and the hardening removal mechanism.

[0027] The advantages of the above technical solution, compared with existing technologies, are as follows: The pretreatment system for recycled water in this invention uses a hardening removal mechanism to thoroughly remove hardening at the beginning, thus extending the service life of the integrated membrane treatment unit. This mechanism reduces the hardness of the wastewater and removes calcium and magnesium ions through chemical precipitation. The hardened water then enters a deep treatment mechanism for further purification. The deeply treated water enters an aeration homogenization tank, where aeration homogenizes the water quality. It then enters a manganese sand filter to remove iron and manganese ions, and the effluent is temporarily stored in a sand filter permeate tank. The sand filter permeate enters the integrated membrane treatment unit, where it filters out colloids and large organic molecules, ultimately flowing into a recycled water tank. Water that meets the production reuse standards after system treatment is stored in the recycled water tank, where it can be used as water for the paper mill (e.g., boiler water). This water recycling saves water and improves water resource utilization. The system also simplifies the process flow, eliminates redundant units (such as machining tanks, manganese sand filters, and aerated biological filters), saves space, and improves the overall efficiency and stability of the system.

[0028] The above description of the utility model is merely an overview of the technical solution of this application. In order to enable those skilled in the art to better understand the technical solution of this application and to implement it based on the description and drawings, and to make the above-mentioned objectives and other objectives, features and advantages of this application easier to understand, the following description is provided in conjunction with the specific embodiments and drawings of this application. Attached Figure Description

[0029] The accompanying drawings are only used to illustrate the principles, implementation methods, applications, features, and effects of specific embodiments of this application and other related content, and should not be considered as limitations on this application.

[0030] In the accompanying drawings of the instruction manual:

[0031] Figure 1 This is one of the flowcharts of the pretreatment system for greywater reuse described in the specific implementation method;

[0032] Figure 2 This is the second schematic diagram of the pretreatment system for greywater reuse described in the specific implementation method;

[0033] Figure 3 This is a flowchart illustrating the deep processing mechanism described in a specific implementation.

[0034] Figure 4 This is a schematic diagram of the integrated membrane processing unit described in a specific embodiment;

[0035] Figure 5 This is a schematic diagram of the reverse osmosis mechanism described in a specific implementation.

[0036] The reference numerals used in the above figures are explained as follows:

[0037] 1. Central water tank,

[0038] 2. First booster pump,

[0039] 3. Emergency pool,

[0040] 4. Second booster pump,

[0041] 5. In addition to hard mechanisms,

[0042] 6. Deep processing mechanism,

[0043] 61. Coagulation reaction tank,

[0044] 62. Coagulation sedimentation tank,

[0045] 63. Fenton reaction tank,

[0046] 64. Transfer pool,

[0047] 65. Cooling tower

[0048] 7. Aeration homogenizing tank,

[0049] 8. Manganese sand filter,

[0050] 9. Sand filter water production tank,

[0051] 10. Integrated membrane processing unit,

[0052] 101. Ultrafiltration unit,

[0053] 102. Ultrafiltration permeate tank,

[0054] 103. Reverse osmosis mechanism,

[0055] 1031. Reverse osmosis membrane

[0056] 104. Reverse osmosis product water tank,

[0057] 11. Reclaimed water tank,

[0058] 12. Filtration mechanism,

[0059] 13. Backwash wastewater collection tank,

[0060] 14. Sedimentation tank,

[0061] 15. Electrodeionization device,

[0062] 16. Concentrated water pool. Detailed Implementation

[0063] To illustrate the possible application scenarios, technical principles, implementable specific solutions, and achievable objectives and effects of this application in detail, the following description, in conjunction with the listed specific embodiments and accompanying drawings, provides a detailed explanation. The embodiments described herein are merely illustrative of the technical solutions of this application and are therefore intended to limit the scope of protection of this application.

[0064] In this document, the term "embodiment" means that a specific feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The term "embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment, nor does it specifically limit its independence or connection with other embodiments. In principle, in this application, as long as there are no technical contradictions or conflicts, the technical features mentioned in each embodiment can be combined in any way to form corresponding implementable technical solutions.

[0065] Unless otherwise defined, the technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the use of related terms herein is merely for the purpose of describing particular embodiments and is not intended to limit this application.

[0066] In the description of this application, the term "and / or" is used to describe the logical relationship between objects, indicating that three relationships can exist. For example, A and / or B means: A exists, B exists, and A and B exist simultaneously. Additionally, the character " / " in this document generally indicates that the preceding and following objects have an "or" logical relationship.

[0067] In this application, terms such as “first” and “second” are used only to distinguish one entity or operation from another, and do not necessarily require or imply any actual quantity, hierarchy or order relationship between these entities or operations.

[0068] Unless otherwise specified, the use of terms such as “comprising,” “including,” “having,” or other similar expressions in this application is intended to cover non-exclusive inclusion, which does not exclude the presence of additional elements in a process, method, or product that includes the stated elements, such that a process, method, or product that includes a list of elements may include not only those defined elements but also other elements not expressly listed, or elements inherent to such a process, method, or product.

[0069] As understood in the Examination Guidelines, in this application, expressions such as "greater than," "less than," and "exceeding" are understood to exclude the stated number; expressions such as "above," "below," and "within" are understood to include the stated number. Furthermore, in the description of the embodiments in this application, "multiple" means two or more (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups" and "multiple times," unless otherwise explicitly specified.

[0070] In the description of the embodiments of this application, the space-related expressions used, such as "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "vertical," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," indicate the orientation or positional relationship based on the orientation or positional relationship shown in the specific embodiments or drawings. These expressions are only for the convenience of describing the specific embodiments of this application or for the reader's understanding, and do not indicate or imply that the device or component referred to must have a specific position, a specific orientation, or be constructed or operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. Furthermore, in this context, it should be understood that when it is mentioned that an element is connected "on" or "below" another element, it can be directly connected not only to the other element "on" or "below," but also indirectly connected to the other element "on" or "below" through an intermediate element.

[0071] Unless otherwise expressly specified or limited, the terms "installation," "connection," "linking," "fixing," and "setting," as used in the description of the embodiments of this application, should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal connection of two components or the interaction between two components. For those skilled in the art to which this application pertains, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0072] Please see Figures 1 to 5 This embodiment relates to a pretreatment system for recycled water, including a hardening removal mechanism 5, a deep treatment mechanism 6, an aeration homogenizing tank 7, a manganese sand filter 8, a sand filter product water tank 9, an integrated membrane treatment unit 10, and a recycled water tank 11; the hardening removal mechanism 5, the deep treatment mechanism 6, the aeration homogenizing tank 7, the manganese sand filter 8, the sand filter product water tank 9, the integrated membrane treatment unit 10, and the recycled water tank 11 are connected in sequence through pipelines.

[0073] Optionally, the hardness removal mechanism 5 is used to remove calcium and magnesium ions from the effluent of the workshop; in this embodiment, the hardness removal mechanism 5 is a hardness removal fluidized bed, which is a wastewater treatment process that combines fluidized bed technology with crystallization principles. It is used to reduce the concentration of hardness ions (such as calcium and magnesium ions) in the water. Its core is to add crystals and reaction agents (such as sodium hydroxide and sodium carbonate) to cause hardness ions to form calcium carbonate and other crystals on the surface of the carrier, and achieve efficient separation through the fluidized bed process. By providing the hardness removal mechanism 5, the problem of incomplete hardness removal in traditional mechanically accelerated clarification tanks is solved, reducing the entry of calcium and magnesium ions into the subsequent membrane system from the source, reducing membrane scaling rate, increasing the service life of the subsequent integrated membrane treatment unit 10, and reducing maintenance costs.

[0074] Optionally, the advanced treatment unit 6 is used for advanced treatment of pollutants in the water; the advanced treatment unit 6 is a process for further removing residual recalcitrant organic matter (such as lignin), suspended solids and colloids in the water after hardening removal, providing high-quality feed water for subsequent membrane treatment and reducing the risk of membrane fouling.

[0075] Optionally, in the aeration homogenizing tank 7, "aeration" refers to introducing air to achieve oxygenation and agitation; "homogenization" refers to making the water quality (such as pH value and pollutant concentration) uniform; and "tank" refers to the enclosed tank used to achieve this function. By setting up the aeration homogenizing tank 7, the problem of water quality fluctuations is solved, and filter media clogging caused by uneven water quality is avoided.

[0076] Optionally, "manganese sand" in manganese sand filter 8 refers to natural filter media whose main component is manganese dioxide; "filter" refers to a filtration device filled with manganese sand filter media, used to remove iron and manganese ions from water. By setting up manganese sand filter 8 to remove iron and manganese ions, the formation of oxide scale on the subsequent membrane surface is avoided, further protecting the integrated membrane treatment unit 10; at the same time, manganese sand filter media has low cost and long service life, reducing operating costs.

[0077] Optionally, the sand filter permeate tank 9 is a buffer storage tank for the effluent after filtration by the manganese sand filter 8. By temporarily storing the effluent from the manganese sand filter 8 in the sand filter permeate tank 9, the influent flow rate of the subsequent integrated membrane treatment unit 10 is balanced (to avoid a sudden increase in membrane pressure due to flow fluctuations), thus playing a flow buffering role. The operating pressure fluctuation of the integrated membrane treatment unit 10 is controlled within ±0.1MPa, avoiding membrane damage caused by flow shocks.

[0078] Optionally, the integrated membrane treatment unit 10 is used to remove suspended and colloidal substances from the water, wherein pollutants are removed through the sieving action of the membrane, further purifying the water quality.

[0079] Optionally, the recycled water tank 11 is a storage tank for water that has been treated by the system and meets the standards for reuse in production. The recycled water tank 11 is the final water storage unit, ensuring continuous water supply for the paper mill. Water that has been treated by the system and meets the standards for reuse in production is stored in the recycled water tank 11. The water in the recycled water tank 11 can be used as water supply for the paper mill (such as boiler water), thus recycling water and saving water.

[0080] Specifically, in the pretreatment system for recycled water in this embodiment, the initial hardening is performed by the hardening removal mechanism 5, which thoroughly removes hardness and improves the service life of the integrated membrane treatment unit 10. The hardening removal mechanism 5 reduces the hardness of the tailwater and removes calcium and magnesium ions from the water through chemical precipitation. The hardened water then enters the deep treatment mechanism 6 for deep purification. The deep-treated water enters the aeration homogenization tank 7, where aeration makes the water quality uniform. It then enters the manganese sand filter tank 8 to remove iron and manganese ions. The effluent is temporarily stored in the sand filter product water tank 9. The sand filter product water enters the integrated membrane treatment unit 10, where colloids and macromolecular organic matter are filtered out. Finally, it flows into the recycled water tank 11. The water that meets the production reuse standards after the entire process is stored in the recycled water tank 11. The water in the recycled water tank 11 can be used as water supply for the paper mill (such as boiler water), thus recycling water, saving water, and improving water resource utilization. The process flow is simplified, redundant units (such as mechanical tanks, manganese sand filters, aerated biological filters, etc.) are removed, saving space and improving the overall efficiency and stability of the system.

[0081] Optionally, in some embodiments, such as Figure 3As shown, the deep treatment mechanism 6 includes a coagulation reaction tank 61, a coagulation sedimentation tank 62, a Fenton reaction tank 63, a transfer tank 64, and a cooling tower 65; the coagulation reaction tank 61 is connected to the hardening removal mechanism 5 through a pipeline; the coagulation reaction tank 61, the coagulation sedimentation tank 62, the Fenton reaction tank 63, the transfer tank 64, and the cooling tower 65 are connected in sequence through pipelines; the cooling tower 65 is connected to the aeration homogenization tank 7 through a pipeline.

[0082] The process involves several steps: Coagulation reactor 61 adds polyaluminum chloride or polyacrylamide, which, through stirring, forms flocs that adsorb fine suspended solids and colloids in the water; coagulation sedimentation tank 62 contains inclined tube packing material, allowing the flocs to settle rapidly and removing over 80% of suspended solids; Fenton reactor 63 adds hydrogen peroxide and ferrous sulfate, generating hydroxyl radicals at pH 3-4 to oxidize and degrade recalcitrant organic matter, reducing chemical oxygen demand (COD); transfer tank 64 temporarily stores the Fenton-treated water, acting as a buffer to prevent fluctuations in the influent to cooling tower 65; and cooling tower 65, a crossflow cooling tower, lowers the water temperature from 35-45℃ to 25-30℃, meeting the temperature requirements of the subsequent aeration homogenization tank 7 and integrated membrane treatment unit 10. Integrating these four dispersed units (coagulation, sedimentation, oxidation, and cooling) shortens the process flow, reduces floor space, and simultaneously removes suspended solids and recalcitrant organic matter, providing high-quality influent for subsequent membrane treatment and reducing the risk of membrane fouling.

[0083] Optionally, in some embodiments, such as Figure 4 As shown, the integrated membrane treatment unit 10 includes an ultrafiltration unit 101, an ultrafiltration permeate tank 102, a reverse osmosis unit 103, and a reverse osmosis permeate tank 104. The ultrafiltration unit 101 is connected to the sand filtration permeate tank 9 via a pipeline. The ultrafiltration unit 101, the ultrafiltration permeate tank 102, the reverse osmosis unit 103, and the reverse osmosis permeate tank 104 are sequentially connected via pipelines. The reverse osmosis permeate tank 104 is connected to the recycled water tank 11 via a pipeline. The ultrafiltration unit 101 uses a hollow fiber membrane module, and the reverse osmosis unit 103 uses a spiral wound reverse osmosis membrane 1031 module.

[0084] The ultrafiltration unit 101 filters colloids, large organic molecules (such as residual lignin), and microorganisms from the water, providing pretreatment for the reverse osmosis unit 103. The ultrafiltration product water tank 102 temporarily stores the ultrafiltration effluent, balancing the influent flow rate and pressure of the reverse osmosis unit 103. The reverse osmosis unit 103, operating at a pressure of 0.8-1.2 MPa, retains more than 99% of ions (such as sodium, chloride, and silicon ions) and small organic molecules in the water. Integrating the ultrafiltration unit 101 and the reverse osmosis unit 103 reduces piping connections and equipment footprint, increases the desalination rate to over 99.5%, and ensures that the product water quality meets the needs of different recycling scenarios in papermaking.

[0085] Optionally, in some embodiments, such as Figure 5 As shown, the reverse osmosis mechanism 103 includes multiple stages of reverse osmosis membranes 1031, and multiple reverse osmosis permeate tanks 104. The reverse osmosis membranes 1031 and the reverse osmosis permeate tanks 104 are connected by pipelines, and the multiple stages of reverse osmosis membranes 1031 correspond to the multiple reverse osmosis permeate tanks 104. The reverse osmosis mechanism 103 can be configured with multiple stages (such as three stages), corresponding to multiple reverse osmosis permeate tanks 104 (each stage of reverse osmosis membrane 1031 corresponds to one permeate tank). The three-stage reverse osmosis system further improves the desalination rate, and each stage of permeate tank stores water independently, allowing for the selection of permeate with different purities according to reuse requirements (e.g., the first-stage reverse osmosis permeate is used for cooling, and the second-stage is used for pulping).

[0086] Optionally, in some embodiments, such as Figures 1 to 5 As shown, the pretreatment system for recycled water also includes a filtration mechanism 12, which is installed on the pipeline between the sand filter water production tank 9 and the ultrafiltration mechanism 101. The filtration mechanism 12 is used to filter fine suspended solids in the water. The filtration mechanism 12 further removes fine suspended solids through fine particle filter media. The filtration mechanism 12 serves as a pre-protection for the ultrafiltration mechanism 101, further extending the service life of the ultrafiltration mechanism 101. Specifically, in this embodiment, the filtration mechanism 12 is a self-cleaning filter.

[0087] Optionally, in some embodiments, such as Figure 4 As shown, the pretreatment system for wastewater reuse also includes a concentrate tank 16, which is connected to the reverse osmosis unit 103 via a pipeline. The concentrate tank 16 is used to store the high-concentration ion wastewater retained by the reverse osmosis unit 103, collecting the reverse osmosis concentrate to avoid direct discharge and pollution, while also enabling the secondary use of the concentrate (such as for flushing sludge), improving overall water resource utilization and reducing wastewater discharge costs.

[0088] Optionally, in some embodiments, such as Figures 1 to 5 As shown, the pretreatment system for recycled water also includes an electro-deionization (EDI) device 15. The EDI device 15 is installed on the pipeline between the reverse osmosis permeate tank 104 and the recycled water tank 11. The EDI device 15 is used to remove impurities from the water for deep purification. The EDI device 15 is a deep purification device that removes ions through electric field-driven ion migration and synergistic action with ion exchange resin. The EDI device 15 removes residual trace ions (such as silicon and boron ions) from the permeate of the reverse osmosis unit 103, improving the resistivity of the effluent and meeting the high-precision production requirements of papermaking (such as high-grade paper pulping). By using the EDI device 15, chemical regeneration is eliminated, reducing chemical reagent consumption and regeneration wastewater discharge, resulting in higher permeate purity.

[0089] Optionally, in some embodiments, such as Figure 4 As shown, the pretreatment system for recycled water also includes a backwash wastewater collection tank 13. The manganese sand filter 8 is connected to the backwash wastewater collection tank 13 via pipelines, the filtration mechanism 12 is connected to the backwash wastewater collection tank 13 via pipelines, and the ultrafiltration mechanism 101 is connected to the backwash wastewater collection tank 13 via pipelines. The backwash wastewater collection tank 13 is used to collect and store the wastewater containing suspended solids generated during the backwashing of the manganese sand filter 8, the filtration mechanism 12, and the ultrafiltration mechanism 101; thereby improving the backwash wastewater recovery rate, further enhancing the overall water resource utilization rate, and reducing operating costs.

[0090] Optionally, in some embodiments, such as Figure 4 As shown, the pretreatment system for recycled water also includes a sedimentation tank 14, which is connected to the backwash wastewater collection tank 13 via a pipeline. The supernatant from the sedimentation tank 14 is also connected to the aeration homogenizing tank 7 via a pipeline. The sedimentation tank 14 is used to treat the backwash wastewater. The sedimentation tank 14 is connected to the backwash wastewater collection tank 13, and the treated supernatant is returned to the aeration homogenizing tank 7 via a pipeline. Sediment is periodically discharged.

[0091] Optionally, in some embodiments, such as Figure 1 As shown, the pretreatment system for recycled water also includes an intermediate water tank 1 and a first lift pump 2. The intermediate water tank 1 is connected to the hardening removal mechanism 5 via a pipeline, and the first lift pump 2 is installed on the pipeline between the intermediate water tank 1 and the hardening removal mechanism 5. Specifically, the intermediate water tank 1 is a buffer tank for temporarily storing workshop effluent; the first lift pump 2 and the second lift pump 4 are power equipment for transporting wastewater; the emergency tank 3 is a backup buffer tank to cope with water quality fluctuations. The intermediate water tank 1 temporarily stores workshop effluent to balance the influent flow rate; the first lift pump 2 is installed between the intermediate water tank 1 and the hardening removal mechanism 5 and is responsible for transporting the effluent to the hardening removal mechanism 5.

[0092] Or in other embodiments, such as Figure 2As shown, the pretreatment system for recycled water also includes an intermediate water tank 1, a first lift pump 2, an emergency tank 3, and a second lift pump 4. The intermediate water tank 1 is connected to the hardening removal mechanism 5 via a pipeline. The first lift pump 2 is installed on the pipeline between the intermediate water tank 1 and the hardening removal mechanism 5. The emergency tank 3 is connected to the intermediate water tank 1 via a pipeline, and the emergency tank 3 is also connected to the hardening removal mechanism 5 via a pipeline. The second lift pump 4 is installed on the pipeline between the emergency tank 3 and the hardening removal mechanism 5. The emergency tank 3 is connected to the intermediate water tank 1. When the water quality in the intermediate water tank 1 exceeds the standard or the first lift pump 2 fails, the second lift pump 4 starts, transporting the backup water (pretreated low-pollution water) in the emergency tank 3 to the hardening removal mechanism 5, ensuring continuous system operation, solving the downtime problem caused by influent water quality and equipment failure, and ensuring the stability of system operation.

[0093] Specifically, such as Figures 1 to 5 As shown, the working principle of the pretreatment system for water reuse in this embodiment is as follows:

[0094] (a) Conventional treatment process (main water flow)

[0095] Inlet water storage and transportation: The wastewater from the papermaking workshop first enters the intermediate water tank 1 for temporary storage, and is then transported to the hardening removal mechanism 5 at a stable flow rate by the first lift pump 2;

[0096] First-end hardness removal: The hardness removal unit 5 reduces the hardness of the effluent to below 50 mg / L through chemical precipitation (addition of sodium carbonate + sodium hydroxide) or ion exchange, removing calcium and magnesium ions;

[0097] Deep purification: The water after hardening enters the deep treatment unit 6:

[0098] First, PAC / PAM is added to coagulation reaction tank 61 to form flocs;

[0099] It enters coagulation sedimentation tank 62, where alum flocs are separated by sedimentation.

[0100] The contents flow into Fenton reactor 63, where they oxidize recalcitrant organic matter and reduce chemical oxygen demand.

[0101] After being buffered in the transfer pool 64, it enters the cooling tower 65 to be cooled to 25-30℃;

[0102] Homogenization and iron and manganese removal: The cooled water enters the aeration homogenization tank 7, where aeration makes the water quality uniform, and then enters the manganese sand filter tank 8 to remove iron and manganese ions. The effluent is temporarily stored in the sand filter product water tank 9.

[0103] Membrane separation and purification: After passing through the filtration unit 12, the sand-filtered permeate enters the integrated membrane treatment unit 10.

[0104] The ultrafiltration unit 101 filters out colloids and macromolecular organic matter, which are then temporarily stored in the ultrafiltration product water tank 102.

[0105] Ultrafiltration permeate enters the reverse osmosis unit 103 (three stages in series), where ions are retained under a pressure of 1.0 MPa. The first-stage reverse osmosis permeate is temporarily stored in the first-stage reverse osmosis permeate tank 104, the second-stage permeate is temporarily stored in the second-stage reverse osmosis permeate tank 104, and the third-stage permeate is temporarily stored in the third-stage reverse osmosis permeate tank 104.

[0106] The reverse osmosis concentrate (containing high concentrations of ions) enters the concentrate tank 16 and is used for sludge flushing or landscaping.

[0107] Final reuse: If high-purity water is required, the tertiary reverse osmosis permeate enters the electro-deionization unit 15, where the resistivity is increased; the final qualified water enters the reuse water pool 11, and is then transported to the papermaking workshop for reuse (such as pulping, cooling, boiler water, etc.).

[0108] (II) Backwash wastewater circulation process

[0109] After the manganese sand filter 8, filtration unit 12, and ultrafiltration unit 101 have been running for 3-10 days (judged based on pressure difference; if pressure difference > 0.2 MPa), start backwashing:

[0110] Backwash wastewater (containing suspended solids) is discharged into backwash wastewater collection tank 13 through pipelines;

[0111] Wastewater is pumped to coagulation sedimentation tank 62, where PAC is added to form flocs, which then settle and separate.

[0112] The supernatant is returned to the aeration homogenizing tank 7 and re-enters the treatment process; the sludge is discharged periodically.

[0113] (III) Emergency Response Procedures

[0114] When the water quality in intermediate water tank 1 exceeds the standard or the first booster pump 2 malfunctions:

[0115] The system automatically switches to emergency mode and activates the second booster pump 4 in emergency pool 3;

[0116] The backup water in emergency pool 3 is transported to hardening removal mechanism 5 to ensure continuous water supply to subsequent units;

[0117] Once the water quality in intermediate pool 1 returns to normal or the first booster pump 2 is repaired, the system will switch back to the normal process.

[0118] Specifically, the beneficial effects of the pretreatment system for water reuse described in this embodiment are as follows:

[0119] Thorough hardening removal extends the lifespan of the integrated membrane treatment unit 10: The hardening removal mechanism 5 reduces hardness to below 50mg / L, lowering the membrane fouling rate, extending membrane lifespan, and reducing maintenance costs; it also enhances the hardening removal effect, reducing membrane system fouling at the source.

[0120] The process is compact, reducing land area and infrastructure costs: The deep treatment unit 6 and the integrated membrane treatment unit 10 integrate 4 and 2 decentralized units respectively, shortening the process flow, reducing the land area, and reducing infrastructure costs; the process flow is simplified, and redundant units (such as mechanical tank, manganese sand filter 8, aerated biological filter, etc.) are removed, saving land area and improving the overall efficiency and stability of the system.

[0121] Water resource utilization rate is significantly improved: Water that meets the production reuse standards after system treatment is stored in the reuse water tank 11. The water in the reuse water tank 11 can be used as water supply for the papermaking workshop (such as pulping, cooling, boiler water, etc.), water recycling saves water; backwash wastewater is recycled to improve water resource utilization rate; concentrated water is recycled for reuse to improve the overall water resource utilization rate.

[0122] Stable operation and wide range of applications: Aeration homogenizing tank 7 and emergency tank 3 ensure stable water quality and flow, reducing system downtime; multi-stage reverse osmosis and EDI devices can provide water of different purities, suitable for various scenarios such as paper cooling, pulping, and high-grade paper production.

[0123] Finally, it should be noted that although the above embodiments have been described in the text and drawings of this application, this should not limit the scope of patent protection of this application. Any technical solutions that are based on the essential concept of this application and utilize the content described in the text and drawings of this application, resulting in equivalent structural or procedural substitutions or modifications, as well as the direct or indirect application of the technical solutions of the above embodiments to other related technical fields, are all included within the scope of patent protection of this application.

Claims

1. A pretreatment system for greywater reuse, characterized in that: It includes a hardening removal mechanism, a deep treatment mechanism, an aeration homogenizing tank, a manganese sand filter, a sand filter permeate tank, an integrated membrane treatment unit, and a reclaimed water tank. The hardening removal mechanism, the deep treatment mechanism, the aeration homogenizing tank, the manganese sand filter, the sand filter permeate tank, the integrated membrane treatment unit, and the recycled water tank are connected in sequence through pipelines. The hardness removal mechanism is used to remove calcium and magnesium ions from the workshop effluent; The advanced treatment unit is used for the advanced treatment of pollutants in the water; The integrated membrane treatment unit is used to remove suspended and colloidal substances from water.

2. The pretreatment system for greywater reuse according to claim 1, characterized in that: The advanced treatment facility includes a coagulation reaction tank, a coagulation sedimentation tank, a Fenton reaction tank, a transfer tank, and a cooling tower; The coagulation reaction tank is connected to the hardening removal mechanism via a pipeline; The coagulation reaction tank, the coagulation sedimentation tank, the Fenton reaction tank, the transfer tank, and the cooling tower are connected in sequence via pipelines. The cooling tower and the aeration homogenizing tank are connected by pipelines.

3. The pretreatment system for greywater reuse according to claim 1 or 2, characterized in that: The integrated membrane treatment unit includes an ultrafiltration unit, an ultrafiltration permeate tank, a reverse osmosis unit, and a reverse osmosis permeate tank; The ultrafiltration unit is connected to the sand filter water production tank via a pipeline; The ultrafiltration unit, the ultrafiltration product water tank, the reverse osmosis unit, and the reverse osmosis product water tank are connected in sequence through pipelines. The reverse osmosis permeate tank and the recycled water tank are connected by pipelines.

4. The pretreatment system for greywater reuse according to claim 3, characterized in that: The reverse osmosis mechanism includes multiple reverse osmosis membranes, and there are multiple reverse osmosis product water tanks; The reverse osmosis membranes are connected to the reverse osmosis permeate tanks via pipelines, and the multiple reverse osmosis membranes correspond to multiple reverse osmosis permeate tanks.

5. The pretreatment system for greywater reuse according to claim 3, characterized in that: The pretreatment system for recycled water also includes a filtration mechanism, which is installed on the pipeline between the sand filter water production tank and the ultrafiltration mechanism. The filtration mechanism is used to filter fine suspended solids in the water.

6. The pretreatment system for greywater reuse according to claim 3, characterized in that: The pretreatment system for recycled water also includes a concentrate tank, which is connected to the reverse osmosis unit via pipelines.

7. The pretreatment system for greywater reuse according to claim 3, characterized in that: The pretreatment system for recycled water also includes an electro-deionization device, which is installed on the pipeline between the reverse osmosis permeate tank and the recycled water tank. The electro-deionization device is used to remove impurities from the water to deeply purify the water quality.

8. The pretreatment system for greywater reuse according to claim 5, characterized in that: The pretreatment system for recycled water also includes a backwash wastewater collection tank. The manganese sand filter is connected to the backwash wastewater collection tank via a pipeline. The filtration mechanism is connected to the backwash wastewater collection tank via a pipeline. The ultrafiltration mechanism is connected to the backwash wastewater collection tank via a pipeline.

9. The pretreatment system for greywater reuse according to claim 8, characterized in that: The pretreatment system for recycled water also includes a sedimentation tank, which is connected to the backwash wastewater collection tank via a pipeline, and the supernatant of the sedimentation tank is connected to the aeration homogenizing tank via a pipeline.

10. The pretreatment system for greywater reuse according to claim 1, characterized in that: The pretreatment system for recycled water also includes an intermediate water tank and a first lift pump. The intermediate water tank is connected to the hardening removal mechanism via a pipeline, and the first lift pump is installed on the pipeline between the intermediate water tank and the hardening removal mechanism; or The pretreatment system for recycled water also includes an intermediate water tank, a first lift pump, an emergency tank, and a second lift pump. The intermediate water tank is connected to the hardening removal mechanism via a pipeline, and the first lift pump is installed on the pipeline between the intermediate water tank and the hardening removal mechanism. The emergency tank is connected to the intermediate water tank via a pipeline, and the emergency tank is connected to the hardening removal mechanism via a pipeline. The second lift pump is installed on the pipeline between the emergency tank and the hardening removal mechanism.

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