An ultrasonic three-dimensional electrochemical algae removal and treatment system and method with nitrogen and phosphorus recovery

Abstract

The present invention discloses an ultrasonic three-dimensional electrochemical algae removal and treatment system and method with nitrogen and phosphorus recovery, which relates to the technical fields of water environment treatment and sewage treatment. The water inlet system is connected to the three-dimensional electrochemical system, and both the activated carbon dosing system and the activated carbon recovery system are connected to the three-dimensional electrochemical system. The activated carbon recovery system is also connected to the activated carbon dosing system. The three-dimensional electrochemical system is connected to the filtration system, which consists of a sump, a primary filtration system, and a precision filtration system. The primary filtration system is connected to the water inlet end of the sump, the water outlet end of the sump is connected to the precision filtration system, the precision filtration system is connected to the electrodialysis system, and the electrodialysis system is connected to the struvite generation system. The present invention realizes the recovery of relatively abundant nutrients such as nitrogen and phosphorus in algae during the algae removal process, avoids the vicious cycle of repeated formation of water blooms, has high removal efficiency, is clean and environmentally friendly, protects the health of the water ecosystem, and has broad application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of water environment treatment and sewage treatment, and particularly relates to an ultrasonic three-dimensional electrochemical algae removal emergency treatment system and method capable of recovering nitrogen and phosphorus. Background Art

[0002] With the rapid development of China's economy, a large amount of pollutants such as nitrogen and phosphorus are discharged into water bodies, causing serious pollution of China's water resources and deterioration of the water environment. It can be seen from the "China Environmental Bulletin" released by the Ministry of Ecology and Environment of China on May 18, 2020: Among the 107 important lakes (reservoirs) where eutrophication status monitoring is carried out, oligotrophic lakes (reservoirs) account for 9.3%, mesotrophic lakes account for 62.6%, slightly eutrophic lakes account for 22.4%, and moderately eutrophic lakes account for 5.6%. Among them, water bodies such as Dianchi Lake, Taihu Lake, and Chaohu Lake still have varying degrees of eutrophication. The intuitive manifestation of water body eutrophication is the explosive growth of algae and the occurrence of water blooms, resulting in the deterioration of water body quality and seriously endangering the natural ecological environment of water bodies. In fact, the large growth of algae is a stress phenomenon caused by excessive nitrogen, phosphorus and other nutrient elements in the water body. During its growth process, it will absorb a large amount of nitrogen, phosphorus and other nutrient elements. Therefore, algae are rich in nitrogen and phosphorus. Conventional algae removal technologies, such as coagulation algae removal and air flotation algae removal, have disadvantages such as the need to add chemical agents during the algae removal process, which is likely to cause secondary pollution and relatively low removal efficiency; while new algae removal technologies, such as advanced oxidation algae removal and electrochemical algae removal technologies, are restricted by long reaction times and low conductivity of natural water bodies during the algae removal process, resulting in low algae removal efficiency. Moreover, neither conventional algae removal technologies nor new algae removal technologies can treat the relatively rich nitrogen and phosphorus elements in algae, and can only discharge them into the environment, unable to completely solve the problem of water body eutrophication, which may form a vicious cycle.

[0003] In order to solve the problems existing in the algae removal technology, such as low removal efficiency, secondary pollution, long reaction time, low conductivity of water bodies resulting in low algae removal efficiency, and the inability to completely remove nutrient elements in water bodies, which may form a vicious cycle, and to make up for the deficiencies of algae removal technologies, it is particularly necessary to design a new ultrasonic three-dimensional electrochemical algae removal emergency treatment system and method capable of recovering nitrogen and phosphorus. Summary of the Invention

[0004] Aiming at the deficiencies in the prior art, the purpose of the present invention is to provide an ultrasonic three-dimensional electrochemical algae removal treatment system and method with nitrogen and phosphorus recovery, which has a reasonable structure design, high removal efficiency, is clean and environmentally friendly, realizes the recovery of relatively rich nitrogen, phosphorus and other nutrient elements in algae during the algae removal process, avoids the vicious cycle of repeated formation of water blooms, and is easy to promote and use.

[0005] To achieve the above object, the present invention is realized by the following technical solutions: An ultrasonic three-dimensional electrochemical algae removal and treatment system with nitrogen and phosphorus recovery, comprising a three-dimensional ultrasonic electrochemical system, an activated carbon dosing and recovery system, a filtration system, and a nitrogen and phosphorus recovery system. The three-dimensional ultrasonic electrochemical system is composed of a water inlet system, a three-dimensional electrochemical system, and an ultrasonic system. The activated carbon dosing and recovery system is composed of an activated carbon dosing system and an activated carbon recovery system. The nitrogen and phosphorus recovery system is composed of an electrodialysis system and a struvite generation system. The water inlet system is connected to the three-dimensional electrochemical system. The activated carbon dosing system is connected to the three-dimensional electrochemical system, adding activated carbon particles into the electrochemical system to form a three-dimensional electrochemical system. The activated carbon recovery system is also connected to the three-dimensional electrochemical system, cleaning and recovering the activated carbon particles discharged from the three-dimensional electrochemical system. The activated carbon recovery system is further connected to the activated carbon dosing system, and its function is to input the activated carbon particles cleaned and recovered by the activated carbon recovery system into the activated carbon dosing system for secondary use. The three-dimensional electrochemical system is connected to the filtration system. The filtration system is composed of a collecting pool, a primary filtration system, and a precision filtration system. The primary filtration system is connected to the water inlet end of the collecting pool. After the polluted water body is treated by the three-dimensional ultrasonic electrochemical system, it enters the primary filtration system, and after being filtered by the primary filtration system, it enters the collecting pool. The water outlet end of the collecting pool is connected to the precision filtration system, and the precision filtration system is connected to the electrodialysis system. The polluted water body enters the precision filtration system from the collecting pool, and after being filtered by the precision filtration system, it enters the electrodialysis system. The electrodialysis system is connected to the struvite generation system.

[0006] Preferably, the water inlet system is composed of a grille, a water inlet pump, a first valve, and a first flowmeter. The grille is placed on the front water inlet side of the water inlet pump. The water inlet pump is connected to the three-dimensional electrochemical system. A first valve and a first flowmeter for adjusting and controlling the water inlet flow rate of the system are installed on the pipeline connecting the water inlet pump and the three-dimensional electrochemical system.

[0007] Preferably, the three-dimensional electrochemical system includes a current stabilizer, a first stirrer, a three-dimensional electrochemical reactor, a cathode plate, and an anode plate. A first stirrer is installed in the three-dimensional electrochemical reactor. The cathode plate and the anode plate are arranged alternately and placed in the three-dimensional electrochemical reactor. The interval between adjacent plates is 1.5 cm. The positive and negative poles of the current stabilizer are respectively connected to the anode plate and the cathode plate. The cathode plate is a stainless steel cathode plate, and the anode plate is a titanium-based platinum electrode anode plate.

[0008] Preferably, the activated carbon dosing system includes an activated carbon dosing pump, a second stirrer, an activated carbon dosing tank, a second valve, and a second flowmeter. A second stirrer is installed in the activated carbon dosing tank. The activated carbon dosing tank is connected to the three-dimensional electrochemical reactor of the three-dimensional electrochemical system through the activated carbon dosing pump. A second valve and a second flowmeter are installed on the pipeline connecting the activated carbon dosing pump and the three-dimensional electrochemical reactor.

[0009] Preferably, the activated carbon recovery system includes a third valve, an activated carbon recovery pump, a third stirrer, a cleaning tank, an activated carbon circulation pump, a submersible pump, and a fourth valve. A third stirrer is installed in the cleaning tank. The cleaning tank is connected to the bottom of the three-dimensional electrochemical reactor in the three-dimensional electrochemical system through the activated carbon recovery pump. A third valve is installed on the pipeline connecting the activated carbon recovery pump and the three-dimensional electrochemical reactor. An activated carbon circulation pump is placed in the cleaning tank and is connected to the activated carbon dosing system through the activated carbon circulation pump. The submersible pump is placed in the clear water tank. The clear water tank is connected to the cleaning tank through the submersible pump. A fourth valve is installed on the pipeline connecting the submersible pump and the cleaning tank.

[0010] Preferably, the ultrasonic system includes an ultrasonic generating device, a first transducer, and a second transducer. The first transducer is placed inside the three-dimensional electrochemical reactor of the three-dimensional electrochemical system to treat algae in the water body by ultrasonic waves and enhance the treatment effect of algae and their released substances. The second transducer is placed in the activated carbon recovery system to clean the impurities attached to the surface of the activated carbon particles. Both the first transducer and the second transducer are connected to the ultrasonic generating device.

[0011] Preferably, the primary filtration system consists of a centrifugal pump, a fifth valve, a third flowmeter, a quartz sand filter, a sixth valve, an activated carbon filter, and a seventh valve. The inlet end of the centrifugal pump is connected to the three-dimensional electrochemical reactor of the three-dimensional electrochemical system. The outlet of the centrifugal pump is connected to the collection tank through the quartz sand filter and the activated carbon filter in sequence. A fifth valve and a third flowmeter are installed on the pipeline connecting the centrifugal pump and the quartz sand filter. A sixth valve is installed on the pipeline connecting the quartz sand filter and the activated carbon filter. A seventh valve is installed on the pipeline connecting the activated carbon filter and the collection tank.

[0012] Preferably, the precision filtration system consists of an eighth valve, a fourth flowmeter, a booster pump, and a precision filter. The inlet end of the booster pump is connected to the collection tank. An eighth valve and a fourth flowmeter for controlling the inlet water flow are installed on the pipeline connecting the booster pump and the collection tank. The outlet of the booster pump is connected to the electrodialysis reactor in the electrodialysis system through the precision filter.

[0013] Preferably, the electrodialysis system includes a voltage stabilizer, an electrodialysis reactor, a ninth valve, a fifth flowmeter, and a tenth valve. The electrodialysis reactor is connected to the voltage stabilizer and is in communication with the clear water tank. A ninth valve and a fifth flowmeter for controlling the flow rate are installed on the pipeline connecting the electrodialysis reactor and the clear water tank. The deionized water generated by the electrodialysis reactor enters the clear water tank through the pipeline for reuse or discharge. The electrodialysis reactor is also in communication with the struvite reactor in the struvite generation system. A tenth valve is installed on the pipeline connecting the electrodialysis reactor and the struvite reactor.

[0014] Preferably, the struvite generation system includes a fourth stirrer, a struvite reactor, a magnesium chloride dosing tank, a magnesium chloride dosing pump, an eleventh valve, and a sixth flowmeter. A fourth stirrer is installed on the struvite reactor. The magnesium chloride dosing tank is connected to the struvite reactor through the magnesium chloride dosing pump. An eleventh valve and a sixth flowmeter for controlling the dosing amount of the magnesium chloride solution are installed on the pipeline connecting the magnesium chloride dosing pump and the struvite reactor. The concentrated water generated by the electrodialysis reactor is directly discharged into the struvite reactor and reacts with the added magnesium chloride solution under suitable conditions to generate struvite. The struvite reactor is in communication with the three-dimensional electrochemical reactor in the three-dimensional electrochemical system through an ion supernatant reflux pump. A seventh flowmeter and a twelfth valve for controlling the reflux amount of the supernatant are installed on the pipeline connecting the struvite reactor and the ion supernatant reflux pump.

[0015] A method for treating algae removal by ultrasonic three-dimensional electrochemical with nitrogen and phosphorus recovery, the steps are as follows: ① The algae-containing water body enters the three-dimensional ultrasonic electrochemical system, and the algae and algae release substances in the water body are removed under the combined action of ultrasonic waves and three-dimensional electrochemical catalytic oxidation: The interaction between ultrasonic waves and the water body produces resonance effect, high-temperature cracking effect, free radical oxidation effect and mechanical shearing effect, which will damage the cell wall and cell membrane structure of algal cells, resulting in the rupture of algal cells, so that the organic matter (including algal toxins, proteins, fats, polysaccharides and other organic matters) in the algal cells is released into the water body, resulting in an increase in the content of organic matters such as algal toxins in the water body. The high-temperature cracking and free radical oxidation produced by the interaction of ultrasonic waves and water will remove some of the organic matters released by the algae into the water body. The remaining algae and algae release substances are partly oxidized on the anode surface of the three-dimensional electrochemical system, and the other part is oxidized by the hydroxyl radicals and hypochlorite ions generated in the three-dimensional electrochemical system. Finally, the carbon, nitrogen and phosphorus-containing organic matters are oxidized into carbon dioxide, water, nitrogen and phosphate, effectively removing the algae and algae release substances and purifying the water quality;

[0016] ② After the algae-containing water body is treated by the ultrasonic three-dimensional electrochemical system, it enters the filtration system. First, it passes through quartz sand filtration to remove larger suspended solid particles in the water; then it passes through activated carbon filtration to remove smaller suspended solids and soluble colloids in the water body by adsorption; then it passes through pressurized precision mechanical filtration to further remove suspended solids and bacteria in the water body;

[0017] ③ The contaminated water body is treated by the filtration system and enters the nitrogen and phosphorus recovery system: The contaminated water body first passes through the electrodialysis system to remove cations such as ammonium ions and anions such as phosphate ions in the water body. The deionized water is discharged into the collection pool and then discharged into the natural water body or reused. The concentrated water in the cathode chamber and the anode chamber enters the struvite generation system. Since the concentrated water contains a large amount of ammonium ions and phosphate ions, only an appropriate amount of magnesium ion-containing solution needs to be added to the struvite reactor, and struvite can be rapidly generated under suitable conditions, completing the recovery and utilization of nitrogen, phosphorus and other nutrient elements in the water body after the removal of algae.

[0018] It should be noted that the activated carbon particles used in the three-dimensional ultrasonic electrochemical system in step ① can be recycled. The used activated carbon particles enter the activated carbon recovery system, and the impurities attached to the surface of the activated carbon are washed by the deionized water generated by the ultrasonic and electrodialysis systems, and then the activated carbon particles after multiple washes re-enter the activated carbon dosing system for reuse.

[0019] In addition, the supernatant after the formation of struvite in the struvite generation system in step ③ will enter the three-dimensional ultrasonic electrochemical system in step ①. Since the supernatant after the formation of struvite is still an ionic solution with a relatively high concentration, if it is directly discharged into the natural water body, it will pollute the environment. Therefore, this system returns the supernatant to the ultrasonic electrochemical system to increase the ion concentration of the system, which can effectively enhance the conductivity of the ultrasonic electrochemical system, improve the electric energy utilization efficiency, strengthen the pollutant removal effect, and at the same time achieve the dual strengthening effects of zero pollutant discharge and reduction of the water treatment cost per ton.

[0020] The beneficial effects of the present invention: This system realizes the recovery and reuse of relatively abundant nitrogen, phosphorus and other nutrient elements in algae during the algae removal process, avoids the vicious cycle of repeated formation of water blooms, effectively makes up for the deficiencies of algae removal technologies, has a high removal efficiency, is clean and environmentally friendly, has zero wastewater discharge, protects the health of the water ecosystem, and has a broad application prospect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be described in detail below in conjunction with the drawings and specific embodiments;

[0022] Figure 1 It is a connection schematic diagram of the three-dimensional ultrasonic electrochemical system, the activated carbon dosing and recovery system of the present invention;

[0023] Figure 2 It is a connection schematic diagram of the filtration system of the present invention;

[0024] Figure 3 It is a connection schematic diagram of the nitrogen and phosphorus recovery system of the present invention;

[0025] Figure 4 It is a process flow diagram of the present invention. Detailed implementation mode

[0026] In order to make the technical means, creative features, achieved purposes and effects of the present invention easy to understand, the present invention will be further described below in conjunction with specific implementation modes.

[0027] Refer to Figures 1-4 In this specific implementation mode, the following technical solutions are adopted: an ultrasonic three-dimensional electrochemical algae removal and treatment system with nitrogen and phosphorus recovery, including a three-dimensional ultrasonic electrochemical system, an activated carbon dosing and recovery system, a filtration system 6 and a nitrogen and phosphorus recovery system. The three-dimensional ultrasonic electrochemical system is composed of a water inlet system 1, a three-dimensional electrochemical system 3 and an ultrasonic system 5. The activated carbon dosing and recovery system is composed of an activated carbon dosing system 2 and an activated carbon recovery system 4. The nitrogen and phosphorus recovery system is composed of an electrodialysis system 9 and a struvite generation system 10.

[0028] The water inlet system 1 is connected to the three-dimensional electrochemical system 3. The activated carbon dosing system 2 is connected to the three-dimensional electrochemical system 3 and is used to add activated carbon to the three-dimensional ultrasonic electrochemical system, adding activated carbon particles into the electrochemical system to form a three-dimensional electrochemical system. The activated carbon recovery system 4 is also connected to the three-dimensional electrochemical system 3 and is used to recover the activated carbon discharged from the three-dimensional electrochemical system 3, cleaning and recovering the activated carbon particles discharged from the three-dimensional electrochemical system. The activated carbon recovery system 4 is also connected to the activated carbon dosing system 2, and its function is to input the activated carbon particles cleaned and recovered by the activated carbon recovery system 4 into the activated carbon dosing system 2 for secondary reuse, which can effectively reduce the operating cost. The three-dimensional electrochemical system 3 is connected to the filtration system 6. The filtration system 6 is composed of a sump 6-1, a primary filtration system 7 and a precision filtration system 8. The primary filtration system 7 is connected to the water inlet end of the sump 6-1. After the polluted water body is treated by the three-dimensional ultrasonic electrochemical system, it enters the primary filtration system 7. After being filtered by the primary filtration system 7, it enters the sump 6-1. The water outlet end of the sump 6-1 is connected to the precision filtration system 8. The precision filtration system 8 is connected to the electrodialysis system 9. The polluted water body enters the precision filtration system 8 from the sump 6-1. After being filtered by the precision filtration system 8, it enters the electrodialysis system 9. The electrodialysis system 9 is connected to the struvite generation system 10.

[0029] Specifically, the composition structures of each system are as follows:

[0030] (1) The water inlet system 1 consists of a grille 1-1, a water inlet pump 1-2, a first valve 1-3, and a first flowmeter 1-4. The grille 1-1 is placed at the front water inlet side of the water inlet pump 1-2. The grille 1-1 is used to isolate larger suspended solids in the influent water to ensure the normal operation of the system. The water inlet pump 1-2 is connected to the three-dimensional electrochemical system 3. The algae-containing water enters the three-dimensional electrochemical system 3 through the water inlet pump 1-2. A first valve 1-3 and a first flowmeter 1-4 for regulating and controlling the influent water flow of the system are installed on the pipeline connecting the water inlet pump 1-2 and the three-dimensional electrochemical system 3.

[0031] (2) The three-dimensional electrochemical system 3 includes a current stabilizer 3-1, a first stirrer 3-2, a three-dimensional electrochemical reactor 3-3, a cathode plate 3-4, and an anode plate 3-5. A first stirrer 3-2 is installed in the three-dimensional electrochemical reactor 3-3. The cathode plate 3-4 and the anode plate 3-5 are arranged alternately and placed in the three-dimensional electrochemical reactor 3-3. The interval between adjacent plates is 1.5 cm. The positive and negative electrodes of the current stabilizer 3-1 are respectively connected to the anode plate 3-5 and the cathode plate 3-4. A stable current is provided to the three-dimensional electrochemical system 3 through the current stabilizer 3-1. The cathode plate 3-4 uses a stainless steel cathode plate, and the anode plate 3-5 uses a titanium-based platinum electrode anode plate. Organic matters such as algae and algae-released substances (including algal toxins, proteins, fats, and polysaccharides, etc.) in the water body directly undergo oxidation on the anode plate 3-5, and at the same time, indirect oxidation occurs under the action of hypochlorite ions generated from chloride ions in the solution.

[0032] (3) The activated carbon dosing system 2 includes an activated carbon dosing pump 2-1, a second stirrer 2-2, an activated carbon dosing barrel 2-3, a second valve 2-4, and a second flowmeter 2-5. A second stirrer 2-2 is installed in the activated carbon dosing barrel 2-3. The activated carbon dosing barrel 2-3 is connected to the three-dimensional electrochemical reactor 3-3 of the three-dimensional electrochemical system 3 through the activated carbon dosing pump 2-1 to add activated carbon to the three-dimensional electrochemical system 3. A second valve 2-4 and a second flowmeter 2-5 are installed on the pipeline connecting the activated carbon dosing pump 2-1 and the three-dimensional electrochemical reactor 3-3.

[0033] (4) The activated carbon recovery system 4 includes a third valve 4-1, an activated carbon recovery pump 4-2, a third agitator 4-3, a cleaning tank 4-4, an activated carbon circulation pump 4-5, a submersible pump 4-6, and a fourth valve 4-7. A third agitator 4-3 is installed in the cleaning tank 4-4. The cleaning tank 4-4 is connected to the bottom of the three-dimensional electrochemical reactor 3-3 in the three-dimensional electrochemical system 3 through the activated carbon recovery pump 4-2, for recovering the activated carbon in the three-dimensional electrochemical reactor 3-3 into the activated carbon recovery system 4. A third valve 4-1 is installed on the pipeline connecting the activated carbon recovery pump 4-2 and the three-dimensional electrochemical reactor 3-3. An activated carbon circulation pump 4-5 is placed in the cleaning tank 4-4 and is connected to the activated carbon dosing system 2 through the activated carbon circulation pump 4-5, for pumping the cleaned activated carbon back into the activated carbon dosing system 2 for reuse after cleaning the activated carbon. The submersible pump 4-6 is placed in the clean water tank 11. The clean water tank 11 is connected to the cleaning tank 4-4 through the submersible pump 4-6. A fourth valve 4-7 is installed on the pipeline connecting the submersible pump 4-6 and the cleaning tank 4-4.

[0034] (5) The ultrasonic system 5 includes an ultrasonic generating device 5-1, a first transducer 5-2, and a second transducer 5-3. Both the first transducer 5-2 and the second transducer 5-3 are connected to the ultrasonic generating device 5-1. The first transducer 5-2 is placed inside the three-dimensional electrochemical reactor 3-3 of the three-dimensional electrochemical system 3, for generating ultrasonic waves in the ultrasonic three-dimensional electrochemical system to treat the algae entering the three-dimensional electrochemical system 3, destroy their cell structures, remove part of the algae and the organic matter released by the algae, and strengthen the treatment effect of the algae and their released substances by ultrasonic treatment of the algae in the water body. The second transducer 5-3 is placed in the activated carbon recovery system 4, for providing ultrasonic waves to the activated carbon recovery system to clean the impurities attached to the surface of the activated carbon particles for reuse after cleaning.

[0035] (6) The primary filtration system 7 consists of a centrifugal pump 7-1, a fifth valve 7-2, a third flowmeter 7-3, a quartz sand filter 7-4, a sixth valve 7-5, an activated carbon filter 7-6, and a seventh valve 7-7. The inlet end of the centrifugal pump 7-1 is connected to the three-dimensional electrochemical reactor 3-3 of the three-dimensional electrochemical system 3. The outlet of the centrifugal pump 7-1 is connected to the collection tank 6-1 through the quartz sand filter 7-4 and the activated carbon filter 7-6 in sequence. A fifth valve 7-2 and a third flowmeter 7-3 are installed on the pipeline connecting the centrifugal pump 7-1 and the quartz sand filter 7-4. A sixth valve 7-5 is installed on the pipeline connecting the quartz sand filter 7-4 and the activated carbon filter 7-6. A seventh valve 7-7 is installed on the pipeline connecting the activated carbon filter 7-6 and the collection tank 6-1.

[0036] (7) The precision filtration system 8 is composed of an eighth valve 8-1, a fourth flowmeter 8-2, a booster pump 8-3, and a precision filter 8-4. The inlet end of the booster pump 8-3 is connected to the sump 6-1. An eighth valve 8-1 and a fourth flowmeter 8-2 for controlling the inlet water flow are installed on the pipeline connecting the booster pump 8-3 and the sump 6-1. The outlet of the booster pump 8-3 is connected to the electrodialysis reactor 9-2 in the electrodialysis system 9 through the precision filter 8-4.

[0037] (8) The electrodialysis system 9 includes a voltage stabilizer 9-1, an electrodialysis reactor 9-2, a ninth valve 9-3, a fifth flowmeter 9-4, and a tenth valve 9-5. The electrodialysis reactor 9-2 is connected to the voltage stabilizer 9-1 and is in communication with the clean water tank 11. The deionized water generated by the electrodialysis system 9 enters the clean water tank 11. A ninth valve 9-3 and a fifth flowmeter 9-4 for controlling the flow are installed on the pipeline connecting the electrodialysis reactor 9-2 and the clean water tank 11. The deionized water generated by the electrodialysis reactor 9-2 enters the clean water tank 11 through a pipeline for reuse or discharge. The clean water tank 11 is connected to the cleaning tank 4-4 through a submersible pump 4-6. The generated deionized water is used for activated carbon cleaning or discharged; the electrodialysis reactor 9-2 is also in communication with the struvite reactor 10-2 in the struvite generation system 10. The concentrated water generated by the electrodialysis system 9 enters the struvite reactor 10-2. A tenth valve 9-5 is installed on the pipeline connecting the electrodialysis reactor 9-2 and the struvite reactor 10-2.

[0038] (9) The struvite generation system 10 includes a fourth stirrer 10-1, a struvite reactor 10-2, a magnesium chloride dosing tank 10-3, a magnesium chloride dosing pump 10-4, an eleventh valve 10-5, and a sixth flowmeter 10-6. A fourth stirrer 10-1 is installed on the struvite reactor 10-2. The magnesium chloride dosing tank 10-3 is connected to the struvite reactor 10-2 through the magnesium chloride dosing pump 10-4. Magnesium chloride solution is added to the struvite reactor 10-2 through the magnesium chloride dosing pump 10-4 for generating struvite. An eleventh valve 10-5 and a sixth flowmeter 10-6 for controlling the dosing amount of the magnesium chloride solution are installed on the pipeline connecting the magnesium chloride dosing pump 10-4 and the struvite reactor 10-2. The concentrated water generated by the electrodialysis reactor 9-2 is directly discharged into the struvite reactor 10-2. The concentrated water contains a large amount of cations such as ammonium ions and anions such as phosphate ions, and reacts with the added magnesium chloride solution to generate struvite under suitable conditions. The struvite reactor 10-2 is connected to the three-dimensional electrochemical reactor 3-3 in the three-dimensional electrochemical system 3 through an ion supernatant reflux pump 3-6. The supernatant after struvite generation is pumped into the three-dimensional electrochemical system 3 through the ion supernatant reflux pump 3-6. A seventh flowmeter 3-7 and a twelfth valve 3-8 for controlling the reflux amount of the supernatant are installed on the pipeline connecting the struvite reactor 10-2 and the ion supernatant reflux pump 3-6. After the solution in the struvite generation system 10 generates struvite, a large amount of chloride ions and other ion supernatants still enter the three-dimensional electrochemical system 3, improving the conductivity of the polluted water body, increasing the current utilization efficiency, and enhancing the three-dimensional electrocatalytic oxidation treatment effect.

[0039] This specific embodiment also provides an ultrasonic three-dimensional electrochemical algae removal and treatment method with nitrogen and phosphorus recovery. The steps are as follows:

[0040] ① The algae-containing water body enters the three-dimensional ultrasonic electrochemical system, and the algae and algae release substances in the water body are removed under the combined action of ultrasonic waves and three-dimensional electrochemical catalytic oxidation: The interaction between ultrasonic waves and the water body generates resonance effects, high-temperature cracking effects, free radical oxidation effects, and mechanical shearing effects, which will damage the cell wall and cell membrane structures of algal cells, resulting in the rupture of algal cells, so that the organic substances (including algal toxins, proteins, fats, polysaccharides, etc.) in the algal cells are released into the water body, leading to an increase in the content of organic substances such as algal toxins in the water body. The high-temperature cracking and free radical oxidation generated by the interaction between ultrasonic waves and water will remove some of the organic substances released by algae into the water body, but cannot completely remove them. A part of the remaining algae and algae release substances are oxidized on the anode surface of the three-dimensional electrochemical system, and the other part is oxidized by the hydroxyl radicals and hypochlorite ions generated in the three-dimensional electrochemical system. Finally, the carbon-, nitrogen-, and phosphorus-containing organic substances are oxidized into carbon dioxide, water, nitrogen, and phosphate, which can effectively remove algae and algae release substances, purify the water quality, and avoid the harm of algal toxins released into the water body due to the destruction of algal structures by ultrasonic waves to the water ecological safety;

[0041] ② After the algae-containing water body is treated by the ultrasonic three-dimensional electrochemical system, it enters the filtration system. First, it passes through quartz sand filtration to remove larger suspended solid particles in the water; then it passes through activated carbon filtration to remove smaller suspended solids and soluble colloids in the water body through adsorption; then it passes through pressurized precision mechanical filtration to further remove suspended solids and bacteria in the water body.

[0042] ③ The polluted water body is treated by the filtration system and enters the nitrogen and phosphorus recovery system: The polluted water body first passes through the electrodialysis system to remove cations such as ammonium ions and anions such as phosphate ions in the water body. The deionized water is discharged into the collection pool and then discharged into the natural water body or reused. The concentrated water in the cathode chamber and the anode chamber enters the struvite generation system. Since the concentrated water contains a large amount of ammonium ions and phosphate ions, only an appropriate amount of magnesium ion-containing solution needs to be added to the struvite reactor, and struvite can be quickly generated under suitable conditions, completing the recovery and utilization of nitrogen, phosphorus and other nutrient elements in the water body after the removal of algae.

[0043] It should be noted that the activated carbon particles used in the three-dimensional ultrasonic electrochemical system in step ① can be recycled. The used activated carbon particles enter the activated carbon recovery system, and the impurities attached to the surface of the activated carbon are washed by the deionized water generated by the ultrasonic and electrodialysis systems, and then the activated carbon particles after multiple washes re-enter the activated carbon dosing system for reuse.

[0044] In addition, the supernatant after the formation of struvite in the struvite generation system in step ③ will enter the three-dimensional ultrasonic electrochemical system in step ①. Since the supernatant after the formation of struvite is still an ionic solution with a relatively high concentration, if it is directly discharged into the natural water body, it will pollute the environment. Therefore, this system returns the supernatant to the ultrasonic electrochemical system to increase the ion concentration of the system, which can effectively enhance the conductivity of the ultrasonic electrochemical system, improve the electric energy utilization efficiency, strengthen the pollutant removal effect, and at the same time achieve the dual strengthening effects of zero discharge of pollutants and reduction of the water treatment cost per ton.

[0045] This specific embodiment effectively solves the problems existing in the algae removal technology, such as low removal efficiency, secondary pollution, long reaction time, low algae removal efficiency due to low water body conductivity during the electrochemical algae removal process, and incomplete removal and utilization of nutrient elements in the water body. Its technical advantages are as follows:

[0046] (1) High-efficiency algae removal: Combining ultrasonic and three-dimensional electrochemical technologies, with complementary technical advantages, it can efficiently remove algae and release organic matter (including algal toxins, proteins, fats, polysaccharides, etc.), avoiding the release of algal toxins into the water body and protecting the health of the water ecosystem.

[0047] (2) Clean and environmentally friendly, zero wastewater discharge: The concentrated water generated by electrodialysis can enter the three-dimensional ultrasonic electrochemical system for reuse, enhancing the sewage treatment effect and making full use of the system wastewater to achieve zero wastewater discharge.

[0048] (3) Recycling and resource utilization of nitrogen and phosphorus: In the process of efficiently removing algae by this technology, a large amount of nitrogen, phosphorus and other nutrient elements absorbed by the algae are synthesized into struvite, which can be recycled as a high-quality slow-release fertilizer.

[0049] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. An ultrasonic three-dimensional electrochemical algae removal and treatment system with nitrogen and phosphorus recovery, characterized in that, it includes a three-dimensional ultrasonic electrochemical system, an activated carbon dosing and recovery system, a filtration system (6) and a nitrogen and phosphorus recovery system. The three-dimensional ultrasonic electrochemical system is composed of a water inlet system (1), a three-dimensional electrochemical system (3) and an ultrasonic system (5). The activated carbon dosing and recovery system is composed of an activated carbon dosing system (2) and an activated carbon recovery system (4). The nitrogen and phosphorus recovery system is composed of an electrodialysis system (9) and a struvite generation system (10). The water inlet system (1) is connected to the three-dimensional electrochemical system (3). The activated carbon dosing system (2) and the activated carbon recovery system (4) are both connected to the three-dimensional electrochemical system (3). The activated carbon recovery system (4) is also connected to the activated carbon dosing system (2). The three-dimensional electrochemical system (3) is connected to the filtration system (6). The filtration system (6) is composed of a sump (6-1), a primary filtration system (7) and a precision filtration system (8). The primary filtration system (7) is connected to the water inlet end of the sump (6-1). The water outlet end of the sump (6-1) is connected to the precision filtration system (8). The precision filtration system (8) is connected to the electrodialysis system (9). The electrodialysis system (9) is connected to the struvite generation system (10); The activated carbon dosing system (2) includes an activated carbon dosing pump (2-1), a second stirrer (2-2), an activated carbon dosing barrel (2-3), a second valve (2-4), a second flowmeter (2-5). A second stirrer (2-2) is installed in the activated carbon dosing barrel (2-3). The activated carbon dosing barrel (2-3) is connected to the three-dimensional electrochemical reactor (3-3) of the three-dimensional electrochemical system (3) through the activated carbon dosing pump (2-1). A second valve (2-4) and a second flowmeter (2-5) are installed on the pipeline connecting the activated carbon dosing pump (2-1) and the three-dimensional electrochemical reactor (3-3); The activated carbon recovery system (4) includes a third valve (4-1), an activated carbon recovery pump (4-2), a third stirrer (4-3), a cleaning pool (4-4), an activated carbon circulation pump (4-5), a submersible pump (4-6), a fourth valve (4-7). A third stirrer (4-3) is installed in the cleaning pool (4-4). The cleaning pool (4-4) is connected to the bottom of the three-dimensional electrochemical reactor (3-3) in the three-dimensional electrochemical system (3) through the activated carbon recovery pump (4-2). A third valve (4-1) is installed on the pipeline connecting the activated carbon recovery pump (4-2) and the three-dimensional electrochemical reactor (3-3). An activated carbon circulation pump (4-5) is placed in the cleaning pool (4-4) and is connected to the activated carbon dosing system (2) through the activated carbon circulation pump (4-5). The submersible pump (4-6) is placed in the clear water tank (11). The clear water tank (11) is connected to the cleaning pool (4-4) through the submersible pump (4-6). A fourth valve (4-7) is installed on the pipeline connecting the submersible pump (4-6) and the cleaning pool (4-4); The described primary filtration system (7) consists of a centrifugal pump (7-1), a fifth valve (7-2), a third flowmeter (7-3), a quartz sand filter (7-4), a sixth valve (7-5), an activated carbon filter (7-6), and a seventh valve (7-7). The inlet end of the centrifugal pump (7-1) is connected to the three-dimensional electrochemical reactor (3-3) of the three-dimensional electrochemical system (3). The outlet of the centrifugal pump (7-1) is sequentially connected to the collection pool (6-1) through the quartz sand filter (7-4) and the activated carbon filter (7-6). A fifth valve (7-2) and a third flowmeter (7-3) are installed on the pipeline connecting the centrifugal pump (7-1) and the quartz sand filter (7-4). A sixth valve (7-5) is installed on the pipeline connecting the quartz sand filter (7-4) and the activated carbon filter (7-6). A seventh valve (7-7) is installed on the pipeline connecting the activated carbon filter (7-6) and the collection pool (6-1). The described precision filtration system (8) consists of an eighth valve (8-1), a fourth flowmeter (8-2), a booster pump (8-3), and a precision filter (8-4). The inlet end of the booster pump (8-3) is connected to the collection pool (6-1). An eighth valve (8-1) and a fourth flowmeter (8-2) for controlling the inlet water flow are installed on the pipeline connecting the booster pump (8-3) and the collection pool (6-1). The outlet of the booster pump (8-3) is connected to the electrodialysis reactor (9-2) in the electrodialysis system (9) through the precision filter (8-4). The described electrodialysis system (9) includes a voltage stabilizer (9-1), an electrodialysis reactor (9-2), a ninth valve (9-3), a fifth flowmeter (9-4), and a tenth valve (9-5). The electrodialysis reactor (9-2) is connected to the voltage stabilizer (9-1). The electrodialysis reactor (9-2) is connected to the clear water tank (11). A ninth valve (9-3) and a fifth flowmeter (9-4) for controlling the flow are installed on the pipeline connecting the electrodialysis reactor (9-2) and the clear water tank (11). The electrodialysis reactor (9-2) is also connected to the struvite reactor (10-2) in the struvite generation system (10). A tenth valve (9-5) is installed on the pipeline connecting the electrodialysis reactor (9-2) and the struvite reactor (10-2). The described struvite generation system (10) includes a fourth stirrer (10-1), a struvite reactor (10-2), a magnesium chloride dosing tank (10-3), a magnesium chloride dosing pump (10-4), an eleventh valve (10-5), and a sixth flowmeter (10-6). A fourth stirrer (10-1) is installed on the struvite reactor (10-2). The magnesium chloride dosing tank (10-3) is connected to the struvite reactor (10-2) through the magnesium chloride dosing pump (10-4). An eleventh valve (10-5) and a sixth flowmeter (10-6) for controlling the dosing amount of the magnesium chloride solution are installed on the pipeline connecting the magnesium chloride dosing pump (10-4) and the struvite reactor (10-2). The struvite reactor (10-2) is connected to the three-dimensional electrochemical reactor (3-3) in the three-dimensional electrochemical system (3) through an ion supernatant reflux pump (3-6). A seventh flowmeter (3-7) and a twelfth valve (3-8) for controlling the reflux amount of the supernatant are installed on the pipeline connecting the struvite reactor (10-2) and the ion supernatant reflux pump (3-6).

2. The ultrasonic three-dimensional electrochemical algae removal and treatment system with nitrogen and phosphorus recovery according to claim 1, characterized in that, the described water inlet system (1) consists of a grille (1-1), a water inlet pump (1-2), a first valve (1-3), and a first flowmeter (1-4). The grille (1-1) is placed on the front water inlet side of the water inlet pump (1-2). The water inlet pump (1-2) is connected to the three-dimensional electrochemical system (3). A first valve (1-3) and a first flowmeter (1-4) for adjusting and controlling the water inlet flow rate of the system are installed on the pipeline connecting the water inlet pump (1-2) and the three-dimensional electrochemical system (3).

3. The ultrasonic three-dimensional electrochemical algae removal and treatment system with nitrogen and phosphorus recovery according to claim 1, characterized in that, the described three-dimensional electrochemical system (3) includes a current stabilizer (3-1), a first stirrer (3-2), a three-dimensional electrochemical reactor (3-3), a cathode plate (3-4), and an anode plate (3-5). A first stirrer (3-2) is installed in the three-dimensional electrochemical reactor (3-3). The cathode plate (3-4) and the anode plate (3-5) are arranged alternately and placed in the three-dimensional electrochemical reactor (3-3). The interval between adjacent plates is 1.5 cm. The positive and negative poles of the current stabilizer (3-1) are respectively connected to the anode plate (3-5) and the cathode plate (3-4). The cathode plate (3-4) is made of a stainless steel cathode plate, and the anode plate (3-5) is made of a titanium-based platinum electrode anode plate.

4. The ultrasonic three-dimensional electrochemical algae removal and treatment system with nitrogen and phosphorus recovery according to claim 1, characterized in that, The ultrasonic system (5) described above includes an ultrasonic generating device (5-1), a first transducer (5-2), and a second transducer (5-3). The first transducer (5-2) is placed inside the three-dimensional electrochemical reactor (3-3) of the three-dimensional electrochemical system (3), and the second transducer (5-3) is placed in the activated carbon recovery system (4). Both the first transducer (5-2) and the second transducer (5-3) are connected to the ultrasonic generating device (5-1).

5. An ultrasonic three-dimensional electrochemical algae removal and treatment method with nitrogen and phosphorus recovery, characterized in that, using the treatment system described in claim 1, the treatment steps are as follows: ① The algae-containing water enters the three-dimensional ultrasonic electrochemical system, and the algae and algae release substances in the water are removed under the combined action of ultrasonic waves and three-dimensional electrochemical catalytic oxidation; ② After the algae-containing water is treated by the ultrasonic three-dimensional electrochemical system, it enters the filtration system. First, it passes through quartz sand filtration to remove larger suspended solid particles in the water; then it passes through activated carbon filtration to remove smaller suspended solids and soluble colloids in the water through adsorption; then it passes through pressurized precision mechanical filtration to further remove suspended solids and bacteria in the water; ③ The polluted water is treated by the filtration system and enters the nitrogen and phosphorus recovery system: The polluted water first passes through the electrodialysis system to remove ammonium cations and phosphate anions in the water. The deionized water is discharged into the collection pool and then discharged into the natural water body or reused. The concentrated water in the cathode chamber and the anode chamber enters the struvite generation system. The concentrated water contains a large amount of ammonium ions and phosphate ions. A magnesium ion-containing solution is added to the struvite reactor to generate struvite, completing the recovery and utilization of nitrogen and phosphorus nutrient elements in the water after the algae are removed.

6. An ultrasonic three-dimensional electrochemical algae removal and treatment method with nitrogen and phosphorus recovery according to claim 5, characterized in that, the activated carbon particles used in the three-dimensional ultrasonic electrochemical system in step ① are recovered. The used activated carbon particles enter the activated carbon recovery system, and the impurities attached to the surface of the activated carbon are cleaned by the deionized water generated by the ultrasonic and electrodialysis systems. Then, the activated carbon particles after multiple cleanings are re-entered into the activated carbon dosing system for reuse.

7. An ultrasonic three-dimensional electrochemical algae removal and treatment method with nitrogen and phosphorus recovery according to claim 5, characterized in that, the supernatant after the struvite is formed in the struvite generation system in step ③ enters the three-dimensional ultrasonic electrochemical system in step ①. The supernatant after the struvite is formed is still an ionic solution with a high concentration. The supernatant is discharged back to the ultrasonic electrochemical system to increase the ion concentration of the system, enhance the conductivity of the ultrasonic electrochemical system, and strengthen the pollutant removal effect.

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