Integrated system for pure water production and wastewater recovery

Abstract

The utility model provides a kind of pure water preparation and wastewater recovery integrated system, comprising: pure water preparation subsystem and wastewater treatment subsystem are connected in turn;Pure water preparation subsystem includes: raw water storage unit, raw water pretreatment unit and pure water preparation unit;Pure water preparation unit includes primary desalting device, secondary desalting device and raw water reflux passage, one end of raw water reflux passage is connected from secondary desalting device, the other end of raw water reflux passage is accessed raw water storage unit;Wastewater treatment subsystem includes: organic molecule oxidation unit, water quality softening unit and first reflux passage, organic molecule oxidation unit and water quality softening unit are sequentially connected, one end of first reflux passage is connected from water quality softening unit, the other end of first reflux passage is accessed raw water storage unit.It has the advantages of effectively preventing pure water preparation and wastewater recovery integrated system from scaling, reducing equipment maintenance frequency, improving water resource recovery rate and avoiding excessive use of chemical agents.

Description

Technical Field

[0001] This application relates to water treatment technology, and more specifically, to an integrated system for pure water preparation and wastewater recycling. Background Technology

[0002] Pure water production processes generally employ a process flow of pretreatment, reverse osmosis desalination, and electro-deionization purification. In this process, the reverse osmosis unit serves as the core desalination step, using high pressure to drive water molecules through a semi-permeable membrane, while retaining salts and organic matter to form wastewater. This wastewater is then recycled, repeating the above steps.

[0003] However, when existing systems process high-hardness water, if the raw water hardness is high, the wastewater produced by reverse osmosis will continuously concentrate calcium and magnesium ions during the recirculation process, easily causing scale to precipitate on the throttling device and membrane surface. This scaling phenomenon not only leads to equipment blockage and a sharp decline in water production performance, but also forces the system to shut down frequently for maintenance, significantly increasing operating costs.

[0004] To inhibit scaling, traditional processes rely on the continuous addition of acidic agents or scale inhibitors. However, this not only introduces additional chemical pollution risks but also wastes agent resources. In addition, existing recirculation water-saving systems are limited by insufficient anti-scaling capabilities and cannot effectively improve water resource recovery rates, forcing the discharge of large amounts of recyclable wastewater, which wastes water resources and increases the environmental burden.

[0005] The widespread presence of high-hardness water sources, particularly in northern my country, makes it difficult for existing technologies to achieve stable and economical long-term operation, thus failing to meet the demands for deep wastewater resource recovery. Therefore, it is urgent to address issues such as increased maintenance frequency due to scale buildup in existing equipment, water waste, and the risks associated with the introduction of chemical agents. Utility Model Content

[0006] The purpose of this application is to provide an integrated system for pure water preparation and wastewater recycling, which has the advantages of effectively preventing scaling in the integrated system, reducing equipment maintenance frequency, improving water resource recovery rate, and avoiding excessive use of chemical agents.

[0007] This application provides an integrated system for pure water preparation and wastewater recycling, the technical solution of which is as follows:

[0008] An integrated system for pure water preparation and wastewater recycling, characterized in that it comprises: a pure water preparation subsystem and a wastewater treatment subsystem connected in series; the pure water preparation subsystem includes: a raw water storage unit, a raw water pretreatment unit, and a pure water preparation unit, which are sequentially connected, wherein the raw water pretreatment unit is used to filter the raw water; the pure water preparation unit includes a primary desalination device, a secondary desalination device, and a raw water return path, wherein the primary desalination device and the secondary desalination device are sequentially connected, and one end of the raw water return path is connected to the secondary desalination device. The other end of the raw water return path is connected to the raw water storage unit; wherein, the primary desalination unit is used to desalinate the filtered raw water to obtain wastewater to be treated and primary product water, and the secondary desalination unit is used to desalinate the primary product water a second time to obtain pure water and secondary product water returned to the raw water storage unit; the wastewater treatment subsystem includes: an organic molecule oxidation unit, a water softening unit and a first return path, the organic molecule oxidation unit and the water softening unit are connected in sequence, one end of the first return path is connected from the water softening unit, and the other end of the first return path is connected to the raw water storage unit.

[0009] Furthermore, the water softening unit includes at least one of the following devices: a chemical precipitation softening device configured to precipitate scale-forming ions; a nanofiltration membrane softening device configured to retain scale-forming ions; and a fluidized bed crystallization softening device configured to crystallize and precipitate scale-forming ions.

[0010] Furthermore, the chemical precipitation softening device includes: a reagent dispenser, a softening reactor, and a floc sedimentation tank. The outlet of the reagent dispenser is connected to the inlet pipe of the softening reactor, and the softening reactor and the floc sedimentation tank are connected in sequence.

[0011] Furthermore, the wastewater treatment subsystem also includes a wastewater buffer unit, which is connected in series with the organic molecule oxidation unit.

[0012] Furthermore, the wastewater treatment subsystem also includes a second circulation path, one end of which is connected to the water softening unit, and the other end of which is connected to the wastewater buffer unit.

[0013] Furthermore, the organic molecule oxidation unit includes at least one of the following devices: an advanced oxidation device that degrades and oxidizes organic molecules by generating a strong oxidant; an electrocatalytic oxidation device that catalytically oxidizes organic molecules through an electrode reaction; a wet catalytic oxidation device configured to catalytically oxidize organic molecules through a catalyst in an environment where the temperature is greater than a first threshold and the pressure is greater than a second threshold; or a heterogeneous Fenton oxidation device that catalytically oxidizes organic molecules through a solid-phase catalyst.

[0014] Furthermore, the advanced oxidation device can be an ozone oxidation device or an ultraviolet-hydrogen peroxide catalytic oxidation device.

[0015] Furthermore, it also includes a solids recovery subsystem sequentially connected to the wastewater treatment subsystem. The solids recovery subsystem includes a solids recovery unit, which is used to purify the polluted wastewater and recover the target substances obtained from the purification process.

[0016] Furthermore, the solid recovery unit includes an evaporation crystallization device, which is used to evaporate and purify the separated dissolved salt pollutants to crystallize and precipitate salt solids.

[0017] Furthermore, the solids recovery unit includes: a pre-reduction device, which is connected in series with an evaporation crystallization device.

[0018] As can be seen from the above, the integrated system for pure water preparation and wastewater recycling provided in this application, in the process of obtaining pure water by treating raw water through the pure water preparation subsystem, produces wastewater to be treated and primary product water in the first-stage desalination unit, and uses the second-stage desalination unit to treat the primary product water to produce pure water and secondary product water. The secondary product water is recycled and re-enters the pure water preparation process, thereby reducing the consumption of raw water. At the same time, the wastewater treatment subsystem performs organic molecular oxidation and water softening treatment on the wastewater to obtain pretreated water, effectively degrading organic pollutants and removing scale-forming ions. This avoids the problem of scale formation during the return of untreated wastewater without the need for scale inhibitors. The secondary product water obtained after treatment is recycled back to the pure water preparation subsystem to achieve resource recycling. Therefore, it has the advantages of effectively preventing scale formation in the integrated system for pure water preparation and wastewater recycling, reducing equipment maintenance frequency, improving water resource recovery rate, and avoiding excessive use of chemical agents. Attached Figure Description

[0019] Figure 1 This is a flowchart illustrating one embodiment of the present invention. Detailed Implementation

[0020] The technical solutions in specific embodiments of this utility model will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. The components described and shown in the accompanying drawings of this utility model can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this utility model provided in the drawings is not intended to limit the scope of the claimed utility model, but merely represents selected embodiments of the utility model. All other embodiments obtained by those skilled in the art based on the embodiments of this utility model without inventive effort are within the scope of protection of this utility model. Furthermore, in the description of the embodiments of this utility model, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance.

[0021] The common English terms or letters used in this utility model for the purpose of clear description, as well as the concepts used, are for illustrative purposes only and are not intended to be limiting or specific. They should not be used to limit the scope of protection of this utility model based on their Chinese translations or specific letters.

[0022] Traditional pure water production systems often suffer from serious problems with the discharge of high-salinity concentrate. Specifically, traditional reverse osmosis systems typically have low recovery rates, which means that the direct discharge of high-salinity wastewater generated during pure water production not only wastes water resources but also burdens the environment.

[0023] Existing pure water preparation systems are poorly adapted to high-hardness water sources. Specifically, taking the calcium carbonate content per liter of water as an example, when the calcium carbonate concentration exceeds 400 mg / L, the throttling devices (such as wastewater proportioners) and reverse osmosis membrane surfaces in existing wastewater recirculation or recycling processes are highly susceptible to scaling due to calcium and magnesium ion supersaturation, leading to a rapid decline in system efficiency or even system failure. Furthermore, existing integrated pure water preparation and wastewater recovery systems have high energy and chemical consumption. Specifically, in most cases, to control scaling, traditional processes often require frequent chemical cleaning or the addition of large amounts of scale inhibitors, which not only increases system operating costs but may also introduce new pollutants. Simultaneously, the high-pressure discharge of wastewater at the end of the system also results in energy waste.

[0024] Therefore, the existing technology has the following problems:

[0025] 1. Scaling leads to poor system reliability: As calcium and magnesium ions in high-hardness water are continuously concentrated in the reflux circulation, they are very easy to precipitate on the throttling device and the surface of the reverse osmosis membrane to form scale, causing equipment blockage, water production performance degradation, and even the need to frequently replace membrane elements, resulting in high maintenance costs.

[0026] Second, there is an upper limit to the water resource recovery rate: In order to avoid scaling, traditional recirculation systems have to control the recovery rate to a low level, and a large amount of recyclable concentrate is still discharged, failing to truly maximize the utilization of water resources.

[0027] Third, strong dependence on chemical agents: In order to inhibit scaling, it is often necessary to continuously add acidic agents or scale inhibitors, which not only increases operating costs, but also poses the risk of chemical residues polluting water quality. Moreover, the consumption of agents is itself a waste of resources.

[0028] This application proposes an integrated system for pure water preparation and wastewater recycling, comprising: a pure water preparation subsystem and a wastewater treatment subsystem connected in series; the pure water preparation subsystem includes: a raw water storage unit, a raw water pretreatment unit, and a pure water preparation unit, which are connected sequentially, wherein the raw water pretreatment unit is used to filter the raw water; the pure water preparation unit includes a primary desalination device, a secondary desalination device, and a raw water return path, wherein the primary desalination device and the secondary desalination device are connected sequentially, and one end of the raw water return path is connected to the secondary desalination device. The other end of the raw water return path is connected to the raw water storage unit; wherein, the primary desalination unit is used to desalinate the filtered raw water to obtain wastewater to be treated and primary product water, and the secondary desalination unit is used to desalinate the primary product water to obtain pure water and secondary product water returned to the raw water storage unit; the wastewater treatment subsystem includes: an organic molecule oxidation unit, a water softening unit and a first return path, the organic molecule oxidation unit and the water softening unit are connected in sequence, one end of the first return path is connected from the water softening unit, and the other end of the first return path is connected to the raw water storage unit.

[0029] Specifically, the raw water storage unit is used to store raw water to be treated, balance the raw water supply with the processing capacity of subsequent units, and avoid the system's continuous operation from being affected by fluctuations in the raw water supply. This can be achieved through stainless steel water tanks, concrete water storage pools, or other means.

[0030] The raw water pretreatment unit is used to filter raw water, removing impurities such as suspended solids, colloids, and organic matter, reducing the turbidity and pollution index of the raw water, and protecting the core components of the subsequent pure water preparation unit from clogging or contamination. In one embodiment, the raw water pretreatment unit can be implemented using a multi-media filter and an activated carbon filter, etc.

[0031] The pure water preparation unit is used to perform deep desalination treatment on pretreated raw water, removing almost all ions, trace organic matter, microorganisms, etc., and ultimately producing pure water that meets specific standards, such as a resistivity of 18 megohms per centimeter or higher, while simultaneously separating wastewater. Both the primary and secondary desalination units can employ membrane separation, adsorption, or precipitation technologies, such as reverse osmosis membranes and microfiltration membranes. These are primarily used for wastewater desalination, separating inorganic salts, dissolved solids, and other impurities from the liquid phase. The raw water return path can be understood as the piping system connecting the secondary desalination unit and the raw water storage unit. It utilizes components such as check valves and flow control valves to precisely guide the water flow, ensuring the safe return of secondary permeate to the raw water storage unit.

[0032] The organic molecule oxidation unit is a device that degrades organic molecules in wastewater using chemical or physical methods. This can be achieved through ozone catalytic oxidation, ultraviolet photocatalytic oxidation, and other methods. Furthermore, the main function of this unit is to reduce the promoting effect of organic matter on subsequent scaling processes, thereby reducing the risk of equipment clogging.

[0033] Water softening units can be implemented by adding appropriate chemical reagents, ion exchange resin devices, electrodialysis devices, or thermal evaporation devices to selectively remove scale-forming factors such as calcium ions, magnesium ions, and silicon ions from wastewater, thus preventing precipitation during subsequent treatment.

[0034] The first return flow path can be understood as the pipeline system connecting the water softening unit and the raw water storage unit. It can achieve precise water flow guidance by setting components such as check valves and flow control valves, ensuring that the softened water can safely return to the raw water storage unit.

[0035] A raw water storage unit refers to a container or device used to temporarily store raw water. It can be implemented using structures such as water tanks or water pools, providing a stable water supply to the system and serving as a key node for water quality regulation.

[0036] Specifically, firstly, since the primary product water is treated purified water, the secondary product water is returned to the primary water storage unit through the primary water storage unit and the primary water return path, constructing a water resource reuse path in the pure water preparation process, reducing the amount of primary water used, and lowering the primary water consumption rate. Secondly, by integrating the primary water storage unit and the primary return path, a closed-loop path for safe wastewater reuse is constructed, thereby ensuring the long-term stable operation of the system under high hardness water source conditions. The primary return path precisely guides the effluent from the water softening unit to the primary water storage unit. This path selection ensures that the returned water must undergo organic molecule oxidation and water softening treatment by the wastewater treatment subsystem before entering the pure water preparation unit. Utilizing the softening unit's directional removal capability of scale-forming ions, the potential for scaling caused by ion concentration is blocked at the source. The setting of two return paths allows the treated water to participate in pure water preparation again, thereby achieving efficient recycling, improving the overall water resource recovery efficiency, and maintaining the dynamic balance of system operation.

[0037] This application solves the scaling problem caused by the concentration of scale-forming ions such as calcium and magnesium during the pure water preparation process using high-hardness water sources, and achieves efficient wastewater recovery and resource utilization. The working principle is as follows: While the pure water preparation subsystem prepares pure water, it also recycles treated secondary permeate. Wastewater generated by the pure water preparation subsystem is directly connected to the wastewater treatment subsystem. In this subsystem, the organic molecule oxidation unit and the water softening unit work synergistically to purify the water, eliminating scaling risks through organic matter degradation and scale-forming ion removal, respectively. Finally, the treated water obtained from the wastewater treatment subsystem is returned to the raw water storage unit to participate in the pure water preparation process, achieving water resource utilization and completing a closed-loop process for deep wastewater resource utilization. Thus, the subsystems are connected in series to jointly solve the problems of poor adaptability to high-hardness water sources and wastewater discharge, ensuring the long-term stable operation of the system.

[0038] In summary, the subsystems are connected in series to form a collaborative chain: the pure water preparation subsystem first internally recycles the treated water resources, then provides the wastewater to be treated; the wastewater treatment subsystem precisely eliminates scaling factors and deeply purifies the water, and then returns the purified water to the pure water preparation subsystem to continue participating in the preparation of pure water. Therefore, the integrated pure water preparation and wastewater recycling system in this embodiment can not only adapt to high hardness water sources, but also effectively solve the problems of wastewater reuse and discharge, and has low operating energy consumption while ensuring long-term stable operation.

[0039] Furthermore, the primary and secondary desalination units include, but are not limited to: reverse osmosis (RO), forward osmosis (FO), or membrane distillation (MD).

[0040] Reverse osmosis (RO) devices, driven by high pressure, desalinate wastewater by removing contaminants such as salt ions and small organic molecules, achieving high precision. However, RO devices have high requirements for the quality of the influent. Forward osmosis, on the other hand, desalinates wastewater based on osmotic pressure difference, with lower energy consumption. Membrane distillation, based on temperature difference, desalinates wastewater with a near 100% rejection rate for salt and organic contaminants, and has lower requirements for influent water quality. In one embodiment, the first-stage desalination unit uses a first-stage reverse osmosis unit (RO-1), and the second-stage desalination unit uses a second-stage reverse osmosis unit (RO-2). The RO unit can also be equipped with an energy recovery device to recover the high-pressure energy from the RO unit and use it to pressurize the influent, reducing the energy consumption of the influent.

[0041] This application further proposes that a water softening unit includes at least one of the following devices: a chemical precipitation softening device configured to precipitate scale-forming ions; a nanofiltration membrane softening device configured to retain scale-forming ions; and a fluidized bed crystallization softening device configured to crystallize and precipitate scale-forming ions.

[0042] Specifically, a chemical precipitation softening device refers to a device that converts dissolved scale-forming ions into insoluble solids through a chemical reaction. This can be achieved by adding precipitants such as sodium hydroxide, sodium carbonate, and magnesium. In one embodiment, adding sodium hydroxide can raise the pH value, causing carbonate ions to combine with calcium ions to form calcium carbonate precipitate. Further addition of sodium carbonate can dissociate calcium carbonate ions, which then combine with residual calcium ions to further form calcium carbonate precipitate. Finally, adding magnesium will react with hydroxide ions to form magnesium hydroxide flocs. These flocs have strong adsorption properties and can react with silicate ions to form a magnesium silicate complex, thereby precipitating and separating the flocs. In another embodiment, the calcium carbonate content in the wastewater output after treatment by the chemical precipitation softening device is controlled to be below 50 mg / L.

[0043] Nanofiltration (NF) membrane softening devices can utilize membrane modules with selective separation capabilities. Based on the matching relationship between membrane pore size and ion valence state, they can achieve high rejection rates for divalent calcium and magnesium ions, while having lower rejection rates for monovalent sodium and chloride ions. This allows them to effectively retain divalent scale-forming ions while allowing small molecules to pass through.

[0044] A fluidized bed crystallization softening device is a device that promotes the directional crystallization and precipitation of scale-forming ions by regulating fluid dynamics conditions. This can be achieved by setting specific flow rates and crystal nucleus carriers. In a specific embodiment, calcium carbonate seed crystals, magnesium hydroxide seed crystals, or dolomite seed crystals can be added to the fluidized bed crystallization softening device to enable the directional precipitation of scale-forming ions such as calcium and magnesium, making them easier to separate and process.

[0045] Specifically, when treating high-hardness water sources, chemical precipitation softening devices rapidly form flocs of calcium and magnesium ions through reagent addition, facilitating subsequent precipitation and separation. This avoids supersaturation precipitation of ions during the circulating concentration process, making it particularly suitable for the rapid reduction of high-concentration hardness ions. Nanofiltration membrane softening devices employ a selective membrane separation mechanism, achieving highly efficient and selective removal of hardness ions. This eliminates the need for chemical reagents, reduces reliance on chemical agents, and prevents secondary pollution caused by reagent residues in traditional softening methods. Fluidized bed crystallization softening devices utilize fluidized particles as crystal nuclei, allowing ions to form stable solid particles in a controlled environment. This prevents disordered ion deposition on pipe or membrane surfaces, significantly improving the adaptability for treating high-salinity wastewater. These three devices offer flexibility for different water quality scenarios, ensuring seamless integration between the softening process and subsequent concentration stages, fundamentally suppressing the causes of scaling in the system.

[0046] The above technical solutions provide three targeted solutions to address the problem of accurately removing scale-forming ions from high-hardness water sources. These solutions precisely control the concentration of scale-forming ions at the source, effectively avoiding the risk of scaling caused by the continuous concentration of ions during the reflux process, and ensuring the stable operation of the integrated pure water preparation and wastewater recycling system under high load conditions.

[0047] This application further proposes a chemical precipitation softening device comprising: a reagent dispenser, a softening reactor, and a floc sedimentation tank, wherein the outlet of the reagent dispenser is connected to the inlet pipe of the softening reactor, and the softening reactor and the floc sedimentation tank are connected sequentially.

[0048] A reagent dispenser is a device capable of precisely adding chemical reagents to water, which can be implemented using a metering pump, titration device, or jet mixer. In one specific embodiment, the softening reactor can be a reaction vessel with stirring function or a static mixer, providing sufficient contact and reaction space for scale-forming ions and chemical reagents. A flocculant sedimentation tank is a device used to separate suspended solids, which can adopt structural forms such as inclined plate sedimentation tanks, horizontal flow sedimentation tanks, or high-efficiency clarification tanks, achieving effective separation of flocs from water through gravity settling.

[0049] Specifically, this scheme systematically optimizes the removal process of scale-forming ions by clearly defining the specific structure of the chemical precipitation softening device. The reagent dispenser is directly connected to the inlet pipe of the softening reactor, ensuring that the chemical reagent is fully mixed with the wastewater before entering the reactor, avoiding localized over- or under-mixing issues. The softening reactor, as the core reaction space, receives the mixed water flow, providing sufficient reaction conditions for scale-forming ions and reagents to form stable flocs. Subsequently, the generated flocs enter the floc sedimentation tank with the water flow, settling and separating under gravity, effectively intercepting solid impurities. The entire process achieves continuity and stability through sequential connection, significantly reducing the risk of residual sediment.

[0050] The above technical solution not only solves the problems of inaccurate chemical reagent dosing, insufficient reaction, or incomplete precipitate separation, but also provides a reliable guarantee for the deep treatment of high-hardness water sources. When treating wastewater with high hardness, this device can effectively remove scale-forming ions, prevent scaling of reverse osmosis membranes and throttling devices, thereby improving the system's operational stability and recovery rate, and reducing maintenance costs.

[0051] This application further proposes that the above-mentioned wastewater treatment subsystem also includes: a wastewater buffer unit, which is connected in series with the organic molecule oxidation unit.

[0052] Specifically, a wastewater buffer unit is a device used to regulate and stabilize wastewater flow. It can be implemented using a tank structure with water storage function or a dynamic regulating device with flow control function. Introducing a wastewater buffer unit absorbs fluctuations in wastewater flow, preventing sudden changes in flow from impacting subsequent return paths, thereby maintaining the system's pressure stability.

[0053] Furthermore, the wastewater buffer unit, acting as a temporary storage device, supplies the received wastewater to the organic molecular oxidation unit and absorbs flow fluctuations through its capacity, effectively mitigating the problem of unstable wastewater flow. This sequential series connection with the organic molecular oxidation unit ensures that the wastewater undergoes buffering treatment before entering the unit, preventing flow fluctuations from being transmitted to the raw water storage unit and the first return pipeline. Based on this, the wastewater buffer unit significantly reduces the risk of scaling caused by unstable flow in high-hardness water treatment, ensuring the long-term reliability and continuity of the system. In addition, the wastewater buffer unit provides a more stable operating environment for the entire integrated pure water preparation and wastewater recycling system, especially when treating high-hardness water, effectively reducing scaling and thus improving the overall system performance.

[0054] This application further proposes that the wastewater treatment subsystem also includes a second circulation path, one end of which is connected to the water softening unit and the other end of which is connected to the wastewater buffer unit.

[0055] Specifically, the second return path refers to the piping structure used to guide a portion of the liquid output from the water softening unit to the wastewater buffer unit. This can be achieved using corrosion-resistant pipes to ensure stable liquid delivery and adaptability to potential chemical environments. The wastewater buffer unit is a device with containment and mixing functions; it can be a buffer tank or buffer pool with stirring capabilities, used to regulate fluctuations in influent water quality by mixing liquids of different concentrations.

[0056] Furthermore, this solution effectively alleviates the problem of influent pollutant concentration accumulation by constructing a closed-loop regulation mechanism from the water softening unit to the wastewater buffer unit. Specifically, one end of the second return path is connected to the water softening unit, enabling real-time acquisition of the liquid purified by the water softening unit. This liquid has a low concentration due to the partial separation of pollutants. The other end is connected to the wastewater buffer unit, allowing the low-concentration return liquid to fully mix with the pretreated wastewater input from the wastewater treatment subsystem within the buffer unit, thereby actively diluting the pollutant concentration in the influent. The influent water quality of the buffer unit is dynamically adjusted according to the output status of the water softening unit, preventing high-concentration liquid from directly impacting the organic molecule oxidation unit and significantly reducing the risk of supersaturation precipitation of scale-forming ions in the organic molecule oxidation unit. At the same time, it maintains the stable buffering capacity of the buffer unit, providing a fundamental guarantee for the long-term operation of the system under high-hardness water source conditions. Furthermore, the embodiments of this application not only solve the limitation that the wastewater buffer unit can only handle the raw wastewater input, but also realize the dynamic adjustment of the high concentration of pollutants generated during the operation of the organic molecule oxidation unit, thereby significantly reducing the risk of equipment maintenance frequency and system efficiency decline.

[0057] This application further proposes an organic molecule oxidation unit that includes at least one of the following devices: an advanced oxidation device for degrading and oxidizing organic molecules by generating a strong oxidant; an electrocatalytic oxidation device for catalytically oxidizing organic molecules through an electrode reaction; a wet catalytic oxidation device configured to catalytically oxidize organic molecules through a catalyst in an environment where the temperature is greater than a first threshold and the pressure is greater than a second threshold; and a heterogeneous Fenton oxidation device for catalytically oxidizing organic molecules through a solid-phase catalyst.

[0058] Specifically, advanced oxidation devices refer to equipment that uses the high reactivity of strong oxidants such as hydroxyl radicals to degrade various difficult-to-treat organic molecules. They can be achieved using advanced oxidation processes (AOPs) such as ozone oxidation and ultraviolet-hydrogen peroxide catalytic oxidation. Since organic pollutants can encapsulate scale-forming ions or chemically disperse scale-forming ions in the liquid, breaking down large organic molecular chains through advanced oxidation devices can make subsequent water softening treatment more thorough.

[0059] Electrocatalytic oxidation devices are devices that directly oxidize organic matter through electrochemical reactions on the electrode surface. They can be implemented using electrodes of different materials and structures to ensure that the oxidation process is dynamically adjusted according to the characteristics of different organic matter, and to avoid the co-deposition of organic matter and calcium and magnesium ions due to insufficient oxidation.

[0060] A wet catalytic oxidation device refers to a device that operates under high temperature and high pressure conditions, using a catalyst to completely mineralize stubborn organic matter. It can be implemented using a fixed-bed or fluidized-bed reactor. By enhancing catalyst activity, it prevents recalcitrant organic matter from interfering with the removal of scale-forming ions. In one embodiment, the first and second thresholds can be dynamically adjusted according to actual application conditions; this embodiment does not impose such limitations.

[0061] Heterogeneous Fenton oxidation equipment refers to equipment that uses solid-phase catalysts to replace traditional dissolved iron ions for catalytic oxidation. It can be implemented using supported catalysts or monolithic catalysts, and by stabilizing the catalytic active sites, it prevents the introduction of new impurities.

[0062] Specifically, the above-mentioned solutions ensure the efficient and thorough decomposition of organic pollutants in wastewater by providing a diverse range of organic molecule oxidation device options. Advanced oxidation devices utilize the broad spectrum of strong oxidants to cover complex organic compounds, preventing localized scaling caused by specific organic residues. Electrocatalytic oxidation devices ensure dynamic adjustment of the oxidation process through precise controllability of electrode reactions, avoiding secondary pollution. Wet catalytic oxidation devices significantly improve oxidation reaction kinetics under extreme environments, ensuring water softening effects. Heterogeneous Fenton oxidation devices stabilize catalytic active sites through solid-phase supports, ensuring consistently high oxidation efficiency. These devices work together to prevent scaling at the source, creating safe conditions for subsequent high-concentration processes. This effectively solves problems such as increased system blockage risk and rapid membrane element failure caused by insufficient oxidation efficiency, achieving improved water recovery rates and reduced maintenance costs.

[0063] This application further proposes that the advanced oxidation device can be an ozone oxidation device or an ultraviolet-hydrogen peroxide catalytic oxidation device.

[0064] Specifically, ozone oxidation devices utilize the high oxidation potential of ozone molecules to degrade organic matter, and can be implemented using an ozone generator in conjunction with a gas-liquid mixing device. Ultraviolet-hydrogen peroxide catalytic oxidation devices use ultraviolet light to excite hydrogen peroxide, generating highly reactive hydroxyl radicals to oxidize organic matter, and can be implemented using a combination of ultraviolet lamps and hydrogen peroxide dosing devices. These two types of devices can specifically address the problem of complex scaling caused by incomplete oxidation of organic matter.

[0065] Furthermore, the ozone oxidation device utilizes the high oxidation potential of ozone molecules to rapidly attack the double bonds and aromatic ring structures in organic molecules, achieving chain breaking and ring opening of large organic molecules. This prevents long-chain organic molecules from encapsulating scale ions and forming colloidal deposits during subsequent softening processes. The ultraviolet-hydrogen peroxide catalytic oxidation device uses ultraviolet light to excite hydrogen peroxide, generating highly reactive hydroxyl radicals. These radicals have non-selective oxidation capabilities, thoroughly mineralizing recalcitrant small-molecule organic molecules (such as humic acids) and preventing them from acting as scale promoters adsorbed onto the surface of scale-forming ions. Both devices focus on improving the thoroughness and selectivity of organic oxidation, ensuring that the organic matter content in the water entering the water softening unit is reduced to below the critical value, fundamentally reducing the possibility of complex scale formation. Simultaneously, these two devices work in conjunction with other units in the wastewater treatment subsystem, playing a crucial role in the integrated system of pure water preparation and wastewater recycling, effectively addressing the long-term stable operation requirements under high-hardness water sources.

[0066] This application further proposes that the system also includes a solids recovery subsystem sequentially connected to the wastewater treatment subsystem, the solids recovery subsystem including: a solids recovery unit, the solids recovery unit being used to purify the polluted wastewater and recover the target substance obtained from the purification.

[0067] Specifically, the solids recovery unit can be implemented using crystallization devices, drying devices, or incineration devices, such as spray dryers or fluidized bed incinerators. Its main function is to further treat the separated polluted wastewater and recover usable substances.

[0068] The treated water from the wastewater treatment subsystem is returned to the pure water preparation subsystem, while the resulting polluted wastewater enters the solids recovery subsystem. The solids recovery subsystem includes a solids recovery unit, which purifies the pollutants and recovers usable target substances, thereby realizing the resource utilization of the polluted wastewater.

[0069] This application further proposes a solid recovery unit including an evaporation crystallization device, which is used to evaporate and purify the separated dissolved salt pollutants to crystallize and precipitate salt solids.

[0070] Specifically, an evaporation crystallization apparatus refers to a device that concentrates dissolved salts by heating and evaporating a solvent, thereby forming Total Dissolved Solids (TDS) that ultimately crystallize and precipitate out. It can be implemented using a multi-effect evaporator, a mechanical vapor recompression evaporator, or a thin-film evaporator. In practical applications, evaporation crystallization apparatuses can efficiently treat high-concentration brine and realize the resource utilization of salt substances, thus solving the problem of the difficulty in recovering dissolved solids from wastewater. In one embodiment, the evaporation crystallization apparatus can also be sequentially connected to a salt separation and purification device to separate crystalline salts for specific purposes, thereby increasing the value of by-products; for example, a practical recrystallization device can be used to separate crystalline salts.

[0071] Furthermore, this solution integrates an evaporation crystallization device into the solids recovery unit, specifically targeting the evaporation and purification of dissolved salt pollutants separated from the wastewater treatment subsystem. Since the pollutants are effectively separated before entering the evaporation crystallization device, interference from organic matter or suspended impurities is avoided, allowing the evaporation process to focus on salt purification, significantly improving treatment efficiency and product purity. The evaporation crystallization device gradually concentrates the dissolved salts and, under suitable conditions, promotes their crystallization, transforming previously difficult-to-recover dissolved solids into a resource-usable solid form. This process not only reduces liquid discharge but also achieves closed-loop recovery of salts from wastewater, providing reliable support for the system to achieve near-zero emissions. In addition, the integration of the solids recovery unit with the wastewater treatment subsystem ensures greater stability and economy when treating high-salinity wastewater, while also solving the problem of low salt recovery efficiency caused by the lack of a targeted treatment mechanism.

[0072] This application further proposes that the aforementioned solid recovery unit includes a pre-reduction device, which is connected in series with an evaporation and crystallization device.

[0073] Specifically, a pre-concentration unit refers to a device capable of performing preliminary concentration treatment on brine. This can be achieved using reverse osmosis membrane modules, nanofiltration membrane modules, or electrodialysis units. It removes some water in a low-energy manner, thereby significantly reducing the load on the subsequent evaporation and crystallization stages. In one embodiment, membrane concentration methods such as vibrating membranes or Disc Tube Reverse Osmosis (DTRO) can be used to achieve volume reduction, thereby reducing the load and energy consumption of the evaporation and crystallization unit.

[0074] Specifically, this scheme effectively optimizes the energy efficiency of the solids recovery process through the structural design of a pre-concentration unit and an evaporation crystallization unit. The pre-concentration unit first performs preliminary concentration treatment on the initial brine, removing most of the water and significantly increasing the brine concentration. The high-concentration brine after the concentration treatment is then transported to the evaporation crystallization unit for further processing, avoiding the energy waste caused by excessive water content when directly evaporating low-concentration brine. This staged processing mechanism not only improves the overall resource utilization efficiency of the process but also fundamentally reduces energy consumption, while ensuring the economic efficiency and sustainability of the solids recovery process. Furthermore, the sequential series connection of the pre-concentration unit and the evaporation crystallization unit ensures the continuity and stability of the brine process during concentration, providing a reliable guarantee for efficient operation.

[0075] The above technical solution solves the problem of excessive energy consumption caused by directly processing brine using only an evaporation and crystallization device. It optimizes the energy efficiency of the solid recovery process and improves the resource utilization efficiency, demonstrating significant technical effects and practical application value.

[0076] The present application will be further described below through a specific embodiment. It should be noted that the specific devices, technologies and solutions in this embodiment are only applicable to this embodiment and do not limit the present application.

[0077] like Figure 1 As shown, the pretreatment unit is used as the raw water pretreatment unit, and the first-stage reverse osmosis unit (referred to as the first-stage RO unit) and the second-stage reverse osmosis unit (referred to as the second-stage RO unit) are used as pure water preparation units; the advanced oxidation unit is used as the organic molecule oxidation unit for illustration.

[0078] Raw water enters the pretreatment unit through the raw water storage unit for filtration, including but not limited to adsorbing suspended solids through a multi-media filter and adsorbing residual chlorine and organic matter through an activated carbon filter, ensuring that the raw water quality entering the first-stage RO unit meets the requirements for pure water preparation. The first-stage RO unit desalinates the raw water to generate primary permeate and wastewater. The primary permeate is transported to the second-stage RO unit, where it undergoes secondary desalination to obtain secondary permeate and pure water with a resistivity of 18 megohms·cm or higher. The secondary permeate is returned to the raw water storage unit for recycling in the pure water preparation process, while the primary permeate enters the wastewater treatment subsystem for further treatment.

[0079] The primary RO unit is the core desalination unit in pure water production; the secondary RO unit refers to the secondary desalination treatment of pure water to achieve deep purification of the primary product water.

[0080] Wastewater enters the wastewater buffer unit in the wastewater treatment subsystem. After the wastewater buffer unit adjusts the instantaneous fluctuations in water quality and the amount of water, it is fed into the advanced oxidation unit to degrade organic pollutants. Then it is fed into the water softening unit to precipitate and separate scale-forming ions such as calcium, magnesium, and silicon through chemical reactions. The resulting pretreated water is then fed into the wastewater treatment subsystem.

[0081] The secondary RO unit in the wastewater treatment subsystem performs deep desalination and other treatments on the pretreated water. The treated water is then returned to the raw water storage unit to participate in the preparation of pure water, while the polluted wastewater enters the solids recovery subunit.

[0082] The evaporation and crystallization unit in the solids recovery subunit receives polluted wastewater, heats it to vaporize the water, and finally crystallizes dissolved solids into salt solids, which are then discharged. This ultimately achieves zero liquid discharge and potential recovery of solid resources. This embodiment specifically demonstrates the treatment at each level of the unit and the water flow path during the treatment process, forming a complete closed-loop cycle.

[0083] Therefore, the integrated system for pure water preparation and wastewater recycling proposed in this application has the following advantages:

[0084] 1. Through a pretreatment combination of "advanced oxidation + targeted chemical softening" in the wastewater treatment subsystem, scale-forming ions and organic substances that promote scaling are precisely removed, creating safe conditions for subsequent processes. The system can stably treat wastewater with a hardness greater than 400 mg / L and exhibits excellent anti-scaling performance. Simultaneously, targeted pretreatment reduces reliance on scale inhibitors, lowers chemical reagent costs, and reduces energy and chemical consumption.

[0085] 2. The installation of the secondary RO unit effectively purifies the primary permeate produced by the primary RO unit. Finally, the secondary permeate produced by the secondary RO unit is reused in the pure water preparation subsystem, which improves the overall system recovery rate and reduces the amount of wastewater discharged, resulting in an extremely high water resource recovery rate.

[0086] 3. After the influent of the secondary RO unit is treated by the primary RO unit, the required operating pressure is reduced, and an energy recovery device can be used, which reduces the energy consumption per ton of water treated accordingly.

[0087] 4. The evaporation and crystallization unit in the solid recovery subsystem can convert the final polluted wastewater into salt solids, realizing the resource-based and harmless treatment of dissolved solids in wastewater and achieving zero discharge of liquids.

[0088] In this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus.

[0089] The above description is merely a specific embodiment of this utility model, enabling those skilled in the art to understand or implement it. Various modifications to these embodiments will be readily apparent to those skilled in the art, and this utility model is not to be limited to the embodiments described herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An integrated system for pure water preparation and wastewater recycling, characterized in that, include: A pure water preparation subsystem and a wastewater treatment subsystem are connected in series. The pure water preparation subsystem includes: a raw water storage unit, a raw water pretreatment unit, and a pure water preparation unit, which are connected in sequence. The raw water pretreatment unit is used to filter the raw water. The pure water preparation unit includes a primary desalination device, a secondary desalination device, and a raw water return path. The primary and secondary desalination devices are connected sequentially. One end of the raw water return path is connected to the secondary desalination device, and the other end is connected to the raw water storage unit. The primary desalination device is used to desalinate the filtered raw water to obtain wastewater to be treated and primary product water. The secondary desalination device is used to perform secondary desalination on the primary product water to obtain pure water and secondary product water returned to the raw water storage unit. The wastewater treatment subsystem includes an organic molecular oxidation unit, a water softening unit, and a first return flow path. The organic molecular oxidation unit and the water softening unit are connected in sequence. One end of the first return flow path is connected to the water softening unit, and the other end of the first return flow path is connected to the raw water storage unit.

2. The system as described in claim 1, characterized in that, The water softening unit includes at least one of the following devices: A chemical precipitation softening device, wherein the chemical precipitation softening device is configured to precipitate scale ions; A nanofiltration membrane softening device, the nanofiltration membrane softening device being configured to retain scale-forming ions; A fluidized bed crystallization softening device, wherein the fluidized bed crystallization softening device is configured to crystallize and precipitate scale-forming ions.

3. The system as described in claim 2, characterized in that, The chemical precipitation softening device includes: a reagent dispenser, a softening reactor, and a floc sedimentation tank. The outlet of the reagent dispenser is connected to the inlet pipe of the softening reactor, and the softening reactor and the floc sedimentation tank are connected in sequence.

4. The system as described in claim 1, characterized in that, The wastewater treatment subsystem further includes a wastewater buffer unit, which is connected in series with the organic molecule oxidation unit.

5. The system as described in claim 4, characterized in that, The wastewater treatment subsystem further includes a second return flow path, one end of which is connected to the water softening unit, and the other end of which is connected to the wastewater buffer unit.

6. The system as described in claim 1, characterized in that, The organic molecule oxidation unit includes at least one of the following devices: An advanced oxidation device that degrades and oxidizes organic molecules by generating a strong oxidant; An electrocatalytic oxidation device, wherein the electrocatalytic oxidation device catalytically oxidizes organic molecules through electrode reactions; A wet catalytic oxidation device, wherein the wet catalytic oxidation device is configured to catalytically oxidize organic molecules by means of a catalyst in an environment where the temperature is greater than a first threshold and the pressure is greater than a second threshold; A heterogeneous Fenton oxidation apparatus, wherein the heterogeneous Fenton oxidation apparatus catalytically oxidizes organic molecules using a solid-phase catalyst.

7. The system as described in claim 6, characterized in that, The advanced oxidation device can be an ozone oxidation device or an ultraviolet-hydrogen peroxide catalytic oxidation device.

8. The system as described in claim 1, characterized in that, It also includes a solids recovery subsystem sequentially connected to the wastewater treatment subsystem. The solids recovery subsystem includes a solids recovery unit, which is used to purify the polluted wastewater and recover the target substance obtained after purification.

9. The system as described in claim 8, characterized in that, The solid recovery unit includes an evaporation crystallization device, which is used to evaporate and purify the separated dissolved salt pollutants to crystallize and precipitate salt solids.

10. The system as described in claim 9, characterized in that, The solid recovery unit includes a pre-reduction device, which is connected in series with the evaporation and crystallization device.

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