A high-salinity wastewater resource recovery zero-emission device driven by solar energy and a use method thereof

Abstract

The application provides a high-salinity wastewater resource recycling zero-emission device driven by solar energy and a use method thereof. The high-salinity wastewater resource recycling zero-emission device driven by solar energy comprises a first subsystem for primary concentration of wastewater, the first subsystem comprises a solar chimney and the like for controlling heat dissipation in the system, a pump and a pipeline are arranged below a saltwater pool, and are connected to a second subsystem for secondary concentration, and belongs to the technical field of industrial wastewater treatment processes. The application realizes comprehensive utilization of solar energy through photovoltaic-photothermal coupling technology, and deeply treats high-salinity wastewater. The integrated process of photovoltaic-photothermal, a solar chimney, interfacial evaporation, thin-film evaporation, cooling crystallization and electro-catalytic oxidation realizes efficient reuse of inorganic salts in high-salinity wastewater and zero emission of wastewater, and has the characteristics of low energy consumption, low treatment cost, advanced process and environmental protection.

Description

TECHNICAL FIELD

[0001] The application relates to a high-salt wastewater resource recycling zero-emission device driven by solar energy and a use method thereof, and belongs to the technical field of industrial wastewater treatment processes. BACKGROUND

[0002] High-salt wastewater is widely sourced from industrial production processes, such as textile printing and dyeing industry wastewater, seawater desalination treatment wastewater, food processing wastewater, domestic sewage and the like. The high-salt wastewater contains high-concentration salts, and if discharged without treatment, will cause water pollution, destroy ecological balance and cause soil salinization and the like. At present, the treatment methods for the high-salt wastewater mainly include evaporation crystallization, membrane separation, flocculation sedimentation and the like, but these methods have the defects of high energy consumption, complex equipment, cumbersome operation and the like, and may face the problems of secondary pollution such as biochemical sludge, and it is difficult to realize the recycling of inorganic salts and the zero emission of wastewater.

[0003] Therefore, there is an urgent need in the field for a high-salt wastewater resource recycling zero-emission device driven by solar energy and a use method thereof. SUMMARY

[0004] The application aims to solve the problems of high energy consumption and secondary pollution in the process of treating wastewater in the prior art.

[0005] To achieve the purpose of solving the above problems, the technical scheme adopted by the application is to provide a high-salt wastewater resource recycling zero-emission device driven by solar energy and a use method thereof.

[0006] In a first aspect, the application provides a high-salt wastewater resource recycling zero-emission device driven by solar energy, which comprises a first subsystem for primary concentration of wastewater, the first subsystem comprising a solar chimney for controlling heat dissipation in the system, a first plate condenser arranged above the solar chimney, a saltwater pool and a light-heat interface evaporator for evaporating saltwater arranged below the solar chimney, and a water collection tank for collecting condensed water after evaporation arranged below the solar chimney and on both sides of the first plate condenser; a pump and a pipeline are arranged below the saltwater pool and connected to a second subsystem for secondary concentration, the second subsystem comprising a power supply device, an oxidation device and a concentration crystallization device, and a crystallization pool arranged below the power supply device and the concentration crystallization device.

[0007] Preferably, the power supply device comprises a photovoltaic power generation device, the oxidation device is a photovoltaic electrocatalytic oxidizer connected to the photovoltaic power generation device, and the concentration crystallization device comprises a double-effect heat exchanger, a solar water heater for providing heat energy to the double-effect heat exchanger, and a second plate condenser arranged above the double-effect heat exchanger.

[0008] Preferably, the solar chimney is a ring-shaped curved surface or a chamfered semi-transparent plastic shed, the curved surface is parabolic, the chamfered angle is 45-60°, the vertical distance between the chimney base and the liquid surface of the light-heat interface evaporator is kept at 15-50 cm; the solar chimney adopts a light-transmitting material film, the light transmittance is ≥95%, and the material is a polyvinyl chloride film, a polyethylene film or an ethylene-vinyl acetate copolymer film.

[0009] Preferably, the light-heat interface evaporator is composed of a composite fabric and a floating support, the floating support is in the shape of a long strip or a round strip, and the composite fabric is covered and fixed above the floating support.

[0010] Preferably, the upper surface of the composite fabric is a hydrophobic thin fabric, the material includes black polyester (PET) and nylon (PA6 or PA66), the fabric thickness is <2 mm, and the fabric surface is sprayed with carbon black powder; the middle layer is PVA gel, the thickness is <2 mm; and the lower layer is a natural cotton fiber woven fabric, the fabric thickness is <3 mm.

[0011] Preferably, the double-effect mass exchanger is in the form of a thin film evaporator, and has the dual functions of thin film evaporation and cooling.

[0012] Preferably, the double-effect mass exchanger is provided with a plate-type condenser and a water collecting tank at the outlet, for condensing water recycling.

[0013] Preferably, the crystallization pool is provided with a stainless steel mud scraper and a screw pump for collecting and transporting the bottom crystallized salt.

[0014] Preferably, the power supply device further comprises a storage battery arranged between the photovoltaic power generation device and the photovoltaic electro-catalytic oxidizer, for providing power for the motor and the pump to work at night.

[0015] Preferably, the bottom of the crystallization pool is designed with a slope.

[0016] In the second aspect, a use method of the device is provided, comprising the following steps:

[0017] Step 1, during the day, the salt water in the salt water pool of the first subsystem absorbs the heat collected by the solar chimney, evaporates the water through the light-heat interface evaporator, and condenses the water vapor through the first plate-type condenser arranged above the solar chimney, and then returns to the water collecting tank, and the concentrated salt water that is not evaporated is transported to the double-effect mass exchanger of the second subsystem through a pump and a pipeline.

[0018] Step 2, after the concentrated salt water enters the double-effect mass exchanger, the solar water heater pumps the water heated by solar energy into the heating pipe of the double-effect mass exchanger, the waste water flows along the outer wall of the heating pipe in a film shape to perform heat transfer and evaporation, and performs secondary concentration, and the concentrated water vapor is condensed through the second plate-type condenser and then returns to the crystallization pool.

[0019] Step 3, the concentrated brine in the crystallization pool is pumped into the double-effect heat exchanger at night, and the waste water flows along the outer wall of the heating pipe in a film shape to be cooled;

[0020] Step 4, due to the cooling, the salt is supersaturated at low temperature, and crystallizes at the bottom of the pool, the bottom of the pool is designed with a slope, and the crystallized salt is transported out of the pool by a mud scraper and a screw pump for post-processing for production section recycling;

[0021] Step 5, the crystallized residual liquid is pumped into the oxidation device, and the organic pollutants in the solution are mineralized and degraded under the action of the electrode.

[0022] Compared with the prior art, the present application has the following beneficial effects:

[0023] (1) The present application uses a light-heat interface evaporator composed of a composite fabric and a floating support to absorb solar heat to drive the realization of rapid evaporation of the solid-liquid interface;

[0024] (2) The present application is based on the open heat collection and enhanced flow interface evaporation principle of the solar chimney, uses the high-molecular semi-transparent film overhead structure to form a large-area heat collection and air flow effect, generates a larger evaporation potential difference, realizes the synergistic efficient phase change of water, gas and heat, and realizes the efficient low-carbon concentration of high-salinity wastewater;

[0025] (3) The present application uses a double-effect heat exchanger with double functions of membrane evaporation and cooling to realize the secondary concentration of wastewater and the crystallization and recycling of salt;

[0026] (4) The present application uses photovoltaic power generation to drive the electrode catalytic oxidation degradation technology to mineralize and degrade the organic pollutants in the high-concentration crystallization residual liquid, and reduce the influence of organic matter accumulation on salt crystallization;

[0027] (5) The present application uses a plate-type condenser and a water collecting tank to realize the recycling of condensed water. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 It is a structural schematic view of the high-salinity wastewater resource recycling zero-emission device driven by solar energy.

[0029] Figure 2 It is a schematic view of two types of solar chimneys (left: circular curved surface; right: chamfered shape).

[0030] Figure 3 It is a schematic view of a light-heat interface evaporator composed of two types of floating supports (left: rectangular strip, right: circular strip).

[0031] Figure 4 It is a schematic view of a double-effect heat exchanger with membrane evaporation (left) and cooling functions (right).

[0032] Figure 5 Flow chart for two working modes of the double-effect mass exchanger. Top: daytime concentration reflux; bottom: nighttime cooling crystallization.

[0033] Figure 6 Solubility curves of four common salts (Na2SO4, NaCl, K2SO4, KCl) in high-salinity wastewater with temperature (a, b, c, d).

[0034] The figure shows: 1-1, solar chimney; 1-2, light-heat interface evaporator; 1-3, first plate condenser; 1-4, water collection tank; 2-1, photovoltaic power generation device; 2-2, storage battery; 2-3, solar water heater; 2-4, double-effect mass exchanger; 2-5, crystallization tank; 2-6, photovoltaic electro-catalytic oxidizer; 2-7, second plate condenser; 2-8, mud scraper; 2-9, screw pump. DETAILED DESCRIPTION

[0035] In order to make the present application more apparent and easy to understand, the preferred embodiments are described in detail below with reference to the accompanying drawings:

[0036] As shown in Figures 1-6 , the present application provides a high-salinity wastewater resource recycling zero-emission device driven by solar energy and a use method, comprising the following steps:

[0037] Step 1: During the day, the salt water in the salt water pool of the first subsystem absorbs the heat collected by the solar chimney 1-1, evaporates the water through the light-heat interface evaporator 1-2, and condenses the water vapor through the first plate condenser 1-3 arranged above the solar chimney 1-1, and then returns to the water collection tank 1-4. The concentrated salt water that has not been evaporated is pumped and transported to the double-effect mass exchanger 2-4 of the second subsystem through the pipeline.

[0038] Step 2: After the concentrated salt water enters the double-effect mass exchanger 2-4, the solar water heater 2-3 pumps the water heated by solar energy into the heating pipe of the double-effect mass exchanger 2-4, and the wastewater flows along the outer wall of the heating pipe in a film-like manner to conduct heat and evaporate, thereby performing secondary concentration. At the same time, the condensed water vapor after concentration is condensed through the second plate condenser 2-7 and returned to the crystallization tank 2-5. During the process, the photovoltaic power generation device 2-1 and the storage battery 2-2 are used to generate electricity.

[0039] Step 3: At night, the concentrated salt water in the crystallization tank 2-5 is pumped into the double-effect mass exchanger 2-4, and the wastewater flows along the outer wall of the heating pipe in a film-like manner to cool down.

[0040] Step 4: Due to the cooling, the salt is supersaturated at low temperature and crystallizes at the bottom of the tank. The bottom of the tank is designed with a slope, and the crystallized salt is transported and collected outside through the mud scraper 2-8 and the screw pump 2-9 for post-processing and recycling for production.

[0041] Step 5, pumping the crystallization residual liquid into the photovoltaic electrocatalytic oxidizer 2-6, under the action of the electrode, mineralization degrades the organic pollutants in the solution.

[0042] Application Example 1

[0043] A printing and dyeing enterprise in northwest China mainly uses Na2SO4 as the main component of high-salinity wastewater, COD Cr concentration is 200 mg / L, and the concentration of TDS in the influent is 13000 mg / L. The enterprise considers that it is difficult to achieve efficient resource recovery and zero discharge of wastewater by using conventional physical, chemical and biological methods, and decides to use the solar-driven high-salinity wastewater resource recovery zero discharge process of the application to treat high-salinity wastewater. The high-salinity wastewater from the production section is first subjected to a solar chimney interface evaporation system. Under the high-temperature irradiation of the sun, the interface temperature rises sharply, causing the water to evaporate rapidly. The COD Cr of the primary concentrated brine after evaporation is 300 mg / L, and the TDS is 39000 mg / L. In this example, the light-heat interface evaporator of the solar interface evaporation system is composed of black polyester (sprayed with carbon black powder), polyvinyl alcohol gel, cotton fiber woven fabric and rectangular strip-shaped wooden floating supports (as shown in Figure 3 ).The solar chimney adopts a ring-shaped curved surface configuration and is made of polyethylene, with a height of 3 m and a gap height of 20 cm. A plate-type condenser is installed above the chimney, and a water collection tank is installed below the condenser and at the bottom of the chimney for clean water recovery (as shown in Figure 2 ). During the day, the primary concentrated brine is pumped into a double-effect heat exchanger for secondary concentration. The solar water heater pumps the water heated by solar energy into the heating pipe of the double-effect heat exchanger, and the wastewater flows along the outer wall of the heating pipe in a film-like manner to perform heat transfer and evaporation. The COD Cr of the secondary concentrated liquid is 350 mg / L, and the TDS is 80000 mg / L. The double-effect heat exchanger is equipped with a plate-type condenser and a water collection tank. When the hot water vapor contacts the plate wall, it liquefies into water droplets, and the clean water is recovered. At night, the wastewater in the crystallization tank is pumped into the double-effect heat exchanger, and the wastewater flows along the outer wall of the heating pipe in a film-like manner to perform cooling. Due to the cooling, sodium sulfate is supersaturated at low temperature and crystallizes at the bottom of the tank (as shown in Figure 4 , 5 ). The bottom of the tank is designed with a slope (3%), and the crystallized salt is transported out of the tank by a mud scraper and a screw pump for post-treatment and recycling for production section. The crystallization residual liquid is pumped into the oxidation reaction tank, BDD is the anode, and graphite is the cathode to perform the electrochemical catalytic oxidation process. The COD Cr of the treated crystallization residual liquid is 35 mg / L, which is continuously returned to the crystallization tank to dilute the COD CrThe concentration of the organic matter is reduced, and the effect of high concentration of the organic matter on the salt crystallization rate at night is reduced. Thus, the process realizes zero discharge of the high-salt wastewater, and the recovery rate of sodium sulfate is 95%.

[0044] Application Example 2

[0045] A sewage treatment plant in a northwest region has a daily treatment capacity of 30000m 3 / d, and the wastewater mainly comes from textile and dyeing enterprises in an industrial park. The enterprises themselves integrate a pretreatment-biochemical-RO system. The salt content in the concentrated liquid after the process is high, the concentration of the organic pollutants is high, and the effect on the subsequent treatment and discharge is large. The main component in the concentrated water is Na2SO4, the COD Cr concentration is 250mg / L, and the concentration of the TDS of the influent is 15000mg / L. The enterprises decide to use the solar energy driven high-salt wastewater resource recovery zero discharge process to treat the high-salt wastewater. The concentrated liquid in the pretreatment process is pumped to the solar energy interface evaporation system. In summer, the daytime temperature reaches 40℃, the interface temperature sharply rises after high-temperature irradiation, the water continuously evaporates, the COD Cr of the once concentrated salt water after evaporation is 320mg / L, and the TDS is 45000mg / L. In this example, the light-heat interface evaporator of the solar energy interface evaporation system is composed of black nylon (sprayed with carbon black powder), polyvinyl alcohol gel, cotton fiber woven fabric and round strip-shaped wooden floating supports (as shown in Figure 3 ). The solar chimney adopts a chamfered (50°) configuration, the material is polyvinyl chloride, the height is 3.2m, the gap height is 25cm, a plate type condenser is installed above the chimney, and a water collecting tank is installed below the condenser and the bottom of the chamfer for clean water recovery (as shown in Figure 2 ). During the day, the once concentrated salt water is pumped into the double-effect heat exchanger for secondary concentration. The solar water heater pumps the water heated by solar energy into the heating pipe of the double-effect heat exchanger, the wastewater flows along the outer wall of the heating pipe in a film shape to perform heat transfer and evaporation, the COD Cr of the secondary concentrated liquid is 350mg / L, the TDS is 90000mg / L, the double-effect heat exchanger is equipped with a plate type condenser and a water collecting tank, the hot water vapor liquefies into water droplets when it contacts the wall, and the clean water is recovered. At night, the wastewater in the crystallization tank is pumped into the double-effect heat exchanger, the wastewater flows along the outer wall of the heating pipe in a film shape to perform cooling. Due to the cooling, the sodium sulfate is supersaturated at low temperature, and crystallizes at the bottom of the tank. The bottom of the tank is designed with a slope (4%). The crystallized salt is collected and transported outside by a mud scraper and a screw pump for post-treatment and recycling for production. The crystallized residual liquid is pumped into an oxidation reaction tank, BDD is used as the anode, and graphite is used as the cathode to perform an electrochemical catalytic oxidation process. The COD CrThe concentration of the organic pollutants is diluted, and the crystallization rate is accelerated. Thus, the coupling process successfully realizes zero discharge of the high-salinity wastewater, and the recovery rate of sodium sulfate in the wastewater reaches 95%.

[0046] The above is only the preferred embodiment of the present application, and is not any form and substantial limitation of the present application. It should be pointed out that, for ordinary skilled in the art, without departing from the present application, a number of improvements and supplements can also be made, which should be considered as the protection scope of the present application. For those skilled in the art, without departing from the spirit and scope of the present application, some changes, modifications and equivalent changes made by using the above disclosed technical content are equivalent embodiments of the present application; meanwhile, any equivalent changes, modifications and evolution made according to the essential technology of the present application to the above embodiments are still within the scope of the technical solutions of the present application.

Claims

1. A high-salinity wastewater resource recovery zero-emission device driven by solar energy, characterized in that, The device comprises a first subsystem for primary concentration of wastewater, a solar chimney for controlling heat dissipation in the system, a first plate condenser above the solar chimney, a saltwater pool and a light-heat interface evaporator below the solar chimney for evaporation of saltwater, and a water collecting tank on both sides of the solar chimney and below the first plate condenser for collecting condensed water after evaporation; a pump and a pipeline below the saltwater pool are connected to a second subsystem for secondary concentration, which comprises a power supply device, an oxidation device and a concentration crystallization device, and a crystallization pool below the power supply device and the concentration crystallization device. The power supply device comprises a photovoltaic power generation device, the oxidation device is a photovoltaic electrocatalytic oxidizer connected to the photovoltaic power generation device, the concentration crystallization device comprises a double-effect heat exchanger, a solar water heater for providing heat energy to the double-effect heat exchanger, and a second plate condenser above the double-effect heat exchanger; the double-effect heat exchanger is in the form of a thin film evaporator, which has the dual functions of thin film evaporation and cooling. The solar chimney is a ring-shaped curved surface or a chamfered semi-transparent plastic shed, the curved surface is parabolic, the chamfered angle is 45-60°, the vertical distance between the chimney base and the liquid surface of the light-heat interface evaporator is kept at 15-50 cm; the solar chimney adopts a light-transmitting material film with a light transmittance of ≥95%, and the material is a polyvinyl chloride film, a polyethylene film or an ethylene-vinyl acetate copolymer film. The light-heat interface evaporator is composed of a composite fabric and a floating support, the floating support is in the shape of a rectangular strip or a circular strip, and the composite fabric is fixedly covered above the floating support; the upper surface of the composite fabric is a hydrophobic thin fabric, the material includes black polyester and nylon, the fabric thickness is <2 mm, and the fabric surface is sprayed with carbon black powder; the middle layer is PVA gel with a thickness of <2 mm; and the lower layer is a natural cotton fabric with a fabric thickness of <3 mm. The use method of the device for recycling high-salinity wastewater resources driven by solar energy and achieving zero discharge comprises the following steps: Step 1: During the day, the saltwater in the saltwater pool of the first subsystem absorbs the heat collected by the solar chimney, evaporates water through the light-heat interface evaporator, and condenses the water vapor through the first plate condenser above the solar chimney to return to the water collecting tank, and the concentrated saltwater that is not evaporated is pumped to the double-effect heat exchanger in the second subsystem through the pump and the pipeline; Step 2: After the concentrated saltwater enters the double-effect heat exchanger, the solar water heater pumps the water heated by solar energy into the heating pipe of the double-effect heat exchanger, the wastewater flows along the outer wall of the heating pipe in a film shape to conduct heat and evaporate, and the concentrated water vapor is condensed through the second plate condenser to return to the crystallization pool; Step 3: At night, the concentrated saltwater in the crystallization pool is pumped into the double-effect heat exchanger, and the wastewater flows along the outer wall of the heating pipe in a film shape to cool down; Step 4: Due to the cooling, the salt is supersaturated at low temperature and crystallizes at the bottom of the pool, the bottom of the pool is designed with a slope, and the crystallized salt is transported out of the pool by a mud scraper and a screw pump for post-processing and recycling for production sections. Step 5, pumping the crystallization residual liquid to the oxidation device, under the action of the electrode, the organic pollutants in the solution are mineralized and degraded.

2. The high salinity wastewater resource recovery zero emission device driven by solar energy according to claim 1, characterized in that, The double-effect plate-fin heat exchanger outlet mounting condenser and water collecting tank.

3. The high salinity wastewater resource recovery zero emission device driven by solar energy according to claim 1, characterized in that, The crystallization tank is provided with a stainless steel mud scraper and a screw pump for collecting and transporting the bottom crystallized salt.

4. The high salinity wastewater resource recovery zero liquid discharge device driven by solar energy according to claim 1, characterized in that, The power supply device further comprises a storage battery arranged between the photovoltaic power generation device and the photovoltaic electro-catalytic oxidizer.

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