Zero emission method based on combination of membrane method salt separation and evaporative crystallization

Abstract

The invention provides a zero discharge method based on combination of membrane process salt separation and evaporative crystallization, which comprises the following steps: pretreating wastewater to obtain impurity-removed wastewater; separating salt and other dissolved substances in the impurity-removed wastewater by using a membrane-method salt separation technology to form separated wastewater, and evaporating water in the separated wastewater by using an evaporative crystallization technology to realize zero discharge of the wastewater. According to the method, a membrane separation technology and an evaporative crystallization technology are combined, so that industrial wastewater is efficiently treated in an environment-friendly manner, zero discharge of the wastewater is realized, and meanwhile, salt and other dissolved substances in the wastewater are recycled, so that economic benefits and environmental protection benefits are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of wastewater treatment, and in particular to a zero-discharge method based on the combination of membrane salt separation and evaporation crystallization. Background Art

[0002] With the acceleration of modern industrialization, the amount of wastewater discharged from industrial production activities is growing at an unprecedented rate, which poses a serious threat to the natural ecological environment and human living environment. If the various harmful substances contained in the wastewater are directly discharged without effective treatment, it will not only seriously pollute water resources and destroy the water ecological balance, but also may accumulate through the food chain and affect human health.

[0003] Traditional wastewater treatment technologies cover multiple aspects such as physical treatment, chemical treatment and biological treatment. Physical treatment mainly relies on filtration, sedimentation and other means to remove suspended matter and some soluble solids in wastewater; chemical treatment precipitates, oxidizes or neutralizes pollutants in wastewater by adding chemical reagents; biological treatment uses the metabolic activities of microorganisms to decompose organic matter and purify wastewater. Although these technologies can reduce the pollution of wastewater to the environment to a certain extent, they generally have problems such as low treatment efficiency, high operating costs and inability to achieve zero discharge of wastewater. Especially when the wastewater contains high concentrations of salt, the treatment effect of traditional methods is particularly limited, because salt is difficult to be effectively removed and is prone to corrosion and scaling of treatment equipment. Due to the technical limitations of traditional wastewater treatment methods, the current industry has been exploring new processes for wastewater treatment that meet the requirements of contemporary social development.

[0004] In view of this, the present invention is proposed. Summary of the invention

[0005] The first purpose of the present invention is to provide a zero-emission method based on the combination of membrane salt separation and evaporation crystallization. This method uses the selective separation effect of high-precision membrane technology to efficiently separate the salt in the wastewater, and then uses evaporation crystallization technology to convert the separated salt into solid crystals to solve the problems existing in the existing wastewater treatment methods, thereby achieving deep purification and zero emission of wastewater.

[0006] The second object of the present invention is to provide a processing system for realizing the above-mentioned zero-discharge method based on the combination of membrane salt separation and evaporative crystallization.

[0007] In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: A zero-emission method based on the combination of membrane salt separation and evaporative crystallization comprises the following steps: The wastewater is first pretreated to obtain wastewater for removing impurities, and then the membrane salt separation technology is used to separate the salt and other dissolved substances in the wastewater for removing impurities to form separated wastewater, and then the evaporation crystallization technology is used to evaporate the water in the separated wastewater to achieve zero wastewater discharge.

[0008] Preferably, the pretreatment method for pretreating the wastewater includes one or more combinations of physical methods, chemical coagulation methods and biological methods.

[0009] As the initial step of wastewater treatment, pretreatment aims to effectively remove large particles, grease, suspended matter and other impurities in wastewater by using a variety of methods, such as physical sedimentation using gravity to settle suspended matter, filtration using media to remove particulate matter and grease, flotation using bubble adhesion to remove low-concentration suspended matter and grease, chemical coagulation adding coagulants to form floccules to remove colloidal particles and soluble organic matter, and biological methods using microorganisms to degrade organic matter. These methods can be flexibly selected according to the specific characteristics of wastewater and treatment requirements, effectively removing large particles, grease, suspended matter and other impurities in wastewater, creating favorable conditions for subsequent treatment processes, not only improving the operating efficiency and stability of treatment equipment, but also reducing energy consumption and drug consumption, while significantly reducing the risk of membrane contamination and effectively extending the service life of membrane components. This allows for high flexibility in pretreatment of wastewater, thereby maximizing the overall treatment efficiency of wastewater.

[0010] Preferably, after obtaining the de-impurity wastewater, a proper amount of chemical agent is added thereto to adjust the pH value and ion concentration in the de-impurity wastewater.

[0011] By adding acid and alkali reagents, the Ph value of the wastewater for removing impurities can be adjusted to an appropriate range. The Ph value adjustment can affect the concentration of ions in the wastewater for removing impurities, thereby creating more favorable conditions for the subsequent membrane salt separation step. Such adjustment is not only conducive to improving the separation efficiency of the subsequent membrane salt separation technology; at the same time, by accurately controlling the dosage of chemical agents, secondary pollution to the environment can be avoided.

[0012] Preferably, the membrane salt separation technology uses membrane separation technology, and separation of molecules of different particle sizes is achieved by adjusting the pore size and operating parameters of the membrane.

[0013] In the present invention, the wastewater is pre-treated and regulated by chemical agents to form primary treated wastewater, which flows into the membrane salt separation process; membrane separation technology has the advantages of high separation efficiency, simple operation, and small footprint.

[0014] Preferably, the membrane used in the membrane separation technology is at least one of a reverse osmosis membrane, a nanofiltration membrane and an electrodialysis membrane.

[0015] In membrane separation technology, reverse osmosis membrane has high selectivity and high flux, and can effectively remove salt, organic matter and microorganisms in wastewater; nanofiltration membrane is between ultrafiltration and reverse osmosis, and can effectively remove divalent ions and multivalent ions in wastewater, and at the same time, the retention rate of organic matter is also high; electrodialysis membrane uses the action of electric field to make ions in wastewater pass through the membrane layer under the action of electric field force to achieve ion separation. Electrodialysis membrane is suitable for treating wastewater containing specific ions or wastewater that needs to recover specific ions. By selecting at least one membrane that meets the characteristics of wastewater, the salt and other dissolved substances in the preliminary treated wastewater can be efficiently separated, which not only significantly improves the purity and quality of the recycled water, but also brings convenience to subsequent treatment, improves the efficiency and effect of evaporation and crystallization, reduces the energy consumption in the evaporation and crystallization process, and reduces the overall cost, and effectively reduces the pollution of salt to the environment.

[0016] Preferably, the evaporation crystallization technology utilizes heat energy to evaporate the separated wastewater to form water vapor, leaving crystals.

[0017] Preferably, the water vapor formed by evaporation is condensed to produce recycled water, and the recycled water can be used again in the production process.

[0018] Evaporation and crystallization technology can not only effectively remove moisture from wastewater, but also convert salt into solid crystals, which is convenient for subsequent treatment and disposal, and realizes efficient separation of moisture and inorganic salts in the separated wastewater, improves the purity of the recycled water, provides convenience for the resource recycling of inorganic salts, and achieves the goal of zero discharge of wastewater. At the same time, the water vapor formed by evaporation can produce recycled water after condensation, and this recycled water can be used again in the production process, which can save the use of fresh water and alleviate the problem of water shortage, thereby realizing the resource utilization of wastewater and promoting sustainable development.

[0019] The present invention also provides a processing system for realizing a zero-discharge method based on a combination of membrane salt separation and evaporation crystallization, comprising: Pretreatment equipment, membrane salt separation equipment, evaporation crystallization equipment; The pretreatment equipment is used to remove large particles, grease, and suspended matter in wastewater; The membrane salt separation equipment is connected to the pretreatment equipment to separate the salt and other dissolved substances from the impurity removal wastewater discharged from the pretreatment equipment; The evaporation crystallization device is connected to the membrane salt separation device to perform water evaporation treatment on the separated wastewater flowing out of the membrane salt separation device.

[0020] Preferably, the processing system also includes automated control and monitoring equipment for real-time monitoring and adjustment of the operation of each device.

[0021] Specifically, the treatment system effectively removes different impurities from the wastewater through pretreatment, and provides relatively clean wastewater with impurities removed for the subsequent membrane salt separation and evaporation crystallization process, thereby ensuring the efficiency and stability of the entire wastewater treatment process. The application of membrane salt separation equipment enables the salt and other dissolved substances in the wastewater with impurities removed to be effectively separated. This link not only improves the treatment quality of the wastewater, but also reduces the burden on the subsequent evaporation and crystallization steps, and improves the treatment efficiency. The treatment system can achieve zero discharge of wastewater by evaporating the separated wastewater flowing out of the membrane salt separation equipment through evaporation and crystallization equipment, which not only meets environmental protection requirements, but also helps to save water resources and achieve sustainable development. The automated control and monitoring equipment equipped in the treatment system can monitor and adjust the operation of each device in real time. This function not only improves the stability and reliability of the system, but also reduces the difficulty and cost of manual operation, making the entire treatment link more intelligent and automated.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) The technical combination of the present invention achieves deep purification and zero emission of wastewater treatment. The pretreatment step effectively removes large particles, grease, suspended matter and other impurities in the wastewater, creating favorable conditions for subsequent treatment processes. Next, the membrane salt separation technology uses the selective separation effect of high-precision membranes to efficiently separate the salt and other dissolved substances in the wastewater, significantly improving the purity and quality of the recycled water. Finally, the evaporation crystallization technology uses thermal energy to evaporate the separated wastewater, forming water vapor and leaving crystals, achieving the goal of zero emission of wastewater. This combined process not only improves the treatment efficiency of wastewater, but also ensures that the quality of the treated water meets environmental protection standards, truly realizing the resource utilization of wastewater.

[0023] (2) The pretreatment step can flexibly select a variety of methods such as physical methods, chemical coagulation methods and biological methods according to the specific characteristics and treatment requirements of the wastewater, so as to effectively deal with high-salt wastewater from different sources and different components. At the same time, the type of membrane used in the membrane salt separation technology can also be selected according to the characteristics of the wastewater, such as reverse osmosis membrane, nanofiltration membrane and electrodialysis membrane, to achieve more efficient salt separation. This flexibility and adaptability enable the process combination of the present invention to be widely used in the field of wastewater treatment in different industries and regions.

[0024] (3) The pretreatment step effectively removes impurities from wastewater, reducing energy and chemical consumption in the subsequent treatment process. The efficient separation effect of membrane salt separation technology reduces energy consumption in the evaporation and crystallization process. Compared with traditional chemical precipitation or ion exchange methods, membrane salt separation technology not only has higher treatment efficiency, but also reduces the use of chemical agents, reduces treatment costs, and avoids secondary pollution to the environment.

[0025] (4) The treatment system of the present invention is equipped with automatic control and monitoring equipment, which can monitor and adjust the operation of each device in real time. This function not only improves the stability and reliability of the system, but also reduces the difficulty and cost of manual operation, making the entire treatment process more intelligent and automated; this intelligent treatment method not only improves the efficiency and quality of wastewater treatment, but also reduces operation and maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] By describing the embodiments of the present application in more detail in conjunction with the accompanying drawings, the above and other purposes, features and advantages of the present application will become more apparent. The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation of the present application. In the accompanying drawings, the same reference numerals generally represent the same components or steps. Figure 1 A schematic diagram of the overall process of a zero-emission method based on a combination of membrane salt separation and evaporative crystallization provided in an embodiment of the present application. DETAILED DESCRIPTION

[0027] The technical scheme of the present invention will be clearly and completely described below in conjunction with specific embodiments and the accompanying drawings of the specification, but it will be understood by those skilled in the art that the following described embodiments are some embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention, and should not be considered as limiting the scope of the present invention. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative work are within the scope of protection of the present invention. If the specific conditions are not indicated in the embodiments, they are carried out according to normal conditions or the conditions recommended by the manufacturer. If the manufacturer is not indicated in the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0028] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below in conjunction with specific implementation methods.

[0029] The present application provides a zero-discharge method based on the combination of membrane salt separation and evaporation crystallization, see Figure 1As shown. First, the wastewater is sent to the pretreatment equipment to remove large particles, grease, suspended matter and other impurities in the wastewater; the pretreatment equipment contains a sedimentation tank, a flotation device, a filter device, and an adjustment tank; the sedimentation tank removes large particles and suspended matter in the wastewater by natural gravity sedimentation, and the suspended matter particles in the wastewater settle to the bottom to form sludge. The specific sedimentation tank adopts a rectangular structure, and a sludge bucket is set at the bottom to facilitate regular cleaning of the sludge at the bottom of the tank; the flotation device adopts the principle of dissolved air flotation. By injecting tiny bubbles into the wastewater, grease and suspended matter adhere to the bubbles and rise to the water surface to form scum, which is then scraped off by a scraper; the filter device uses media of different particle sizes (such as sand, activated carbon, etc.) for filtration; the adjustment tank is made of stainless steel and is equipped with a stirring device to ensure uniform mixing of wastewater and chemical agents for adjusting the pH and ion concentration of wastewater.

[0030] The wastewater pretreated by the pretreatment equipment is sent to the membrane salt separation equipment, which can separate the salt and other dissolved substances in the pretreated wastewater to form separated wastewater. The membrane salt separation equipment contains multiple membrane components; among them, the reverse osmosis membrane component is made of polyamide material, which has high selectivity and permeability, and can effectively intercept the salt and organic matter in the pretreated wastewater. At the same time, the component is also equipped with an automatic cleaning device to regularly clean the membrane surface to prevent membrane pollution; the nanofiltration membrane component is made of cellulose acetate, which can effectively remove divalent ions and multivalent ions in the pretreated wastewater, while retaining some organic matter; the electrodialysis membrane component can efficiently separate the ions in the pretreated wastewater, especially for divalent ions and multivalent ions.

[0031] The separated wastewater in the membrane salt separation equipment is sent to the evaporation crystallization equipment to evaporate the separated wastewater to produce crystals. The equipment contains an evaporator and a crystallizer. The separated wastewater first enters the evaporator. The evaporator adopts the falling film evaporation principle. The separated wastewater is evenly sprayed on the heating tube wall through a nozzle to form a thin film. The heat conduction effect of the heating tube wall is used to quickly evaporate the water in the separated wastewater. At the same time, the evaporator contains a condensation component to condense the evaporated water vapor into water for recycling; the crystallizer is equipped with a stirring device to prevent crystals from depositing on the wall and bottom of the device.

[0032] The specific method to achieve zero wastewater discharge is carried out in the following steps: First, the wastewater is sent to a sedimentation tank for sedimentation treatment to remove large particles and suspended matter to obtain precipitated wastewater; then the precipitated wastewater is sent to a flotation device through a pipeline for flotation treatment to remove grease and fine suspended matter; then the flotation wastewater is sent to a filtration device for filtration treatment to further remove suspended matter and impurities; then the filtered wastewater is sent to an equalization tank for adjustment treatment, and a pH adjuster is added to the equalization tank to make it evenly mixed with the filtered wastewater, which can ensure that the salt and other dissolved substances in the adjusted wastewater are more easily separated by the membrane salt separation technology used in subsequent links. Then the regulated wastewater is sent to the reverse osmosis membrane assembly for reverse osmosis treatment, and the selective permeability of the reverse osmosis membrane is used to remove the salt and most of the organic matter in the wastewater to obtain fresh water and concentrated water, and the fresh water is discharged through a pipeline; then the concentrated water in the reverse osmosis wastewater is sent to the nanofiltration membrane assembly to further separate the multivalent ions to obtain purer fresh water and high-concentration concentrated water, and the fresh water obtained after nanofiltration is discharged through a pipeline; then the concentrated water obtained after nanofiltration is sent to the evaporator, and the concentrated water after nanofiltration is evaporated by heat energy to evaporate its water, and the evaporated water is introduced into the condensation assembly for condensation treatment to obtain condensed water, and the condensed water is transported to the recovery pool through a pipeline, and the remaining salt and other substances in the concentrated water obtained after evaporation and nanofiltration are sent to the crystallizer for crystallization treatment to form crystals; in the whole process, the operation of each equipment is monitored and processed by automatic control and monitoring equipment.

[0033] Through the above steps, the present invention achieves the effect of zero wastewater discharge by combining membrane salt separation with evaporative crystallization. At the same time, the recovered fresh water and inorganic salts are effectively utilized, reducing production costs and resource consumption; in addition, the process also has a high degree of automation and stability, which can ensure the continuity and reliability of wastewater treatment.

[0034] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A zero-emission method based on the combination of membrane salt separation and evaporative crystallization, characterized in that: The steps include: The wastewater is first pretreated to obtain wastewater for removing impurities, and then the membrane salt separation technology is used to separate the salt and other dissolved substances in the wastewater for removing impurities to form separated wastewater, and then the evaporation crystallization technology is used to evaporate the water in the separated wastewater to achieve zero wastewater discharge.

2. The zero-emission method according to claim 1, characterized in that: The pretreatment method for pretreating the wastewater includes one or more combinations of physical method, chemical coagulation method and biological method.

3. The zero-emission method according to any one of claims 1 to 2, characterized in that: After obtaining the wastewater from which impurities are removed, a proper amount of chemical agents is added thereto to adjust the pH value and ion concentration in the wastewater from which impurities are removed.

4. The zero-emission method according to claim 1, characterized in that: The membrane salt separation technology uses membrane separation technology, which can achieve the separation of molecules with different particle sizes by adjusting the pore size and operating parameters of the membrane.

5. The membrane salt separation technology according to claim 4, characterized in that: The membrane used in the membrane separation technology is at least one of a reverse osmosis membrane, a nanofiltration membrane and an electrodialysis membrane.

6. The zero-emission method according to claim 1, characterized in that: The evaporation crystallization technology utilizes heat energy to evaporate the separated wastewater to form water vapor, leaving crystals.

7. The evaporation crystallization technology according to claim 6, characterized in that: The water vapor formed by evaporation is condensed to generate recycled water, and the recycled water can be used again in the production process.

8. A processing system for the zero-emission method according to any one of claims 1 to 7, characterized in that: include: Pretreatment equipment, membrane salt separation equipment, evaporation crystallization equipment; The pretreatment equipment is used to remove large particles, grease, and suspended matter in wastewater; The membrane salt separation equipment is connected to the pretreatment equipment to separate the salt and other dissolved substances from the impurity removal wastewater discharged from the pretreatment equipment; The evaporation crystallization device is connected to the membrane salt separation device to perform water evaporation treatment on the separated wastewater flowing out of the membrane salt separation device.

9. The processing system according to claim 8, characterized in that The processing system also includes automatic control and monitoring equipment for real-time monitoring and adjusting the operation of each device.

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