Method and apparatus for inactivating pathogenic microorganisms in water by sound-enhanced peracetic acid

Abstract

This invention relates to the field of wastewater treatment technology, disclosing a method and apparatus for inactivating pathogenic microorganisms in water using ultrasound-enhanced peracetic acid. Ultrasonic radiation generates a large number of cavitation bubbles. The enormous energy released by the collapse of these cavitation bubbles can destroy the cell walls and cell membranes of microorganisms, and disperse pathogenic bacterial cell aggregates attached to solid impurities into single-cell states. This reduces the cells' resistance to chemical disinfectants, facilitating further inactivation. After ultrasonic radiation, the pathogenic bacterial cells are dispersed in a single-cell state, effectively reducing the protective effect of the bacterial flocs. Peracetic acid can directly penetrate the damaged cell membrane or diffuse through the bacterial cell membrane to enter the cell interior, acting on intracellular substances to further inactivate the pathogens. This invention is simple to operate, low in cost, and has a significant sterilization effect, possessing high practical value.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, and in particular to a method and apparatus for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid. Background Technology

[0002] Water pollution caused by pathogenic microorganisms is becoming increasingly serious, attracting widespread attention worldwide. Water disinfection is crucial for preventing outbreaks of pathogens and protecting public health. Currently, a growing number of public health problems are prompting the development of more efficient, low-cost, and environmentally friendly water disinfection methods. Several disinfection technologies (i.e., chlorine, ozone, sodium hypochlorite, hydrogen peroxide, and ultraviolet light) are widely used for water disinfection. However, traditional disinfection technologies may produce harmful disinfection byproducts (DBPs), which have potential carcinogenicity and may induce drug resistance genes, posing a serious threat to the ecological environment and public safety.

[0003] Peracetic acid is an organic peroxide and broad-spectrum antibacterial agent, synthesized by reacting acetic acid with hydrogen peroxide (H₂O₂) in the presence of a catalyst such as sulfuric acid. Peracetic acid is a strong oxidizing agent with a high standard reduction potential (1.96V), close to that of H₂O₂ and higher than that of chlorine. Peracetic acid has been widely used in wastewater disinfection, pollutant degradation, and the pulp and paper industry. Compared with some traditional disinfectants, peracetic acid offers advantages for water disinfection and microbial inactivation, including strong bactericidal ability, low pH dependence, ease of technical implementation, and reduced formation of toxic byproducts in treated effluent. Therefore, peracetic acid has become a promising alternative to chlorinated disinfectants in water treatment. However, some problems still exist with peracetic acid. First, the large amount of acetic acid produced by the self-decomposition of peracetic acid can provide a carbon source for the reactivation of pathogens, increasing the risk of pathogen regrowth. Second, the addition of Cu... 2+ Ag + Co 2+ However, peracetic acid catalysts can cause secondary pollution to water. Therefore, combining peracetic acid with other technologies will become a new direction for development in the field of water disinfection.

[0004] Ultrasound refers to sound waves with a frequency of 20 kHz or higher. It has a short wavelength, good directivity, and strong penetrating power. Based on frequency, ultrasound can be divided into low-frequency ultrasound (20-100 kHz) and high-frequency ultrasound (>100 kHz). For low-frequency ultrasound (<100 kHz, typically 20-48 kHz), the key bactericidal mechanism involves mechanical impact, leading to mechanical damage to the bacterial cell membrane. Compared to low-frequency ultrasound, high-frequency ultrasound (>100 kHz) has a stronger inactivation ability against pathogenic microorganisms in aqueous solutions. High-frequency ultrasound can generate cavitation bubbles. These microbubbles can inactivate enzymes and destroy cell membranes, DNA, RNA, and proteins through physical and chemical effects, thereby achieving the purpose of inactivating pathogenic microorganisms. Summary of the Invention

[0005] The purpose of this invention is to provide a method and apparatus for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid, in order to solve the problems existing in the prior art.

[0006] To achieve the above objectives, the present invention provides a method and apparatus for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid, comprising the following steps:

[0007] Insoluble impurities in wastewater are removed through sedimentation.

[0008] Wastewater is treated with ultrasonic radiation to disperse aggregated pathogenic microorganisms into single-cell states. The ultrasonic radiation treatment includes at least two frequencies of ultrasound. When wastewater is treated with ultrasonic radiation of different frequencies, aggregated pathogenic microorganisms in the water are dispersed into single-cell states, the cell membranes are destroyed, and the resistance of pathogenic microorganisms to chemical disinfectants is significantly reduced.

[0009] A strong oxidant is added to the wastewater that has been treated with ultrasonic radiation and stirred to inactivate pathogenic microorganisms in the wastewater. The strong oxidant is a peracetic acid solution. Peracetic acid enters the cell through molecular diffusion or directly through the damaged cell membrane, oxidizes the substances inside the cell, and further inactivates the pathogenic microorganisms in the water.

[0010] Preferably, the ultrasonic radiation treatment further includes:

[0011] Low-frequency ultrasonic waves are arranged below the surface of the wastewater.

[0012] High-frequency ultrasonic waves are arranged at the bottom of the wastewater.

[0013] Preferably, the precipitation time is not less than 10 minutes.

[0014] Preferably, the ultrasonic radiation treatment time is not less than 10 minutes.

[0015] Preferably, the ultrasonic radiation treatment further includes:

[0016] The ultrasonic generator outputs a sinusoidal signal for conversion into ultrasonic waves, and the power density of the ultrasonic generator is not less than 0.038 W / mL.

[0017] Preferably, the ultrasonic radiation treatment further includes:

[0018] Low-frequency ultrasonic waves are positioned 2 cm below the surface of the wastewater.

[0019] Preferably, the concentration of peracetic acid in the wastewater is not less than 26 μM.

[0020] Preferably, the peracetic acid solution contains a peracetic acid mass fraction of not less than 18.04%.

[0021] The present invention also provides a device for inactivating pathogenic microorganisms in water by sound wave enhanced peracetic acid, comprising a sewage inlet zone, an ultrasonic radiation zone and a peracetic acid reaction zone connected in sequence.

[0022] The wastewater inlet area is equipped with an inlet pipe, a flow regulator, and a bypass pipe located at the bottom of the wastewater inlet area. A circular gate I is installed on the inlet pipe, and a circular gate II is installed on the bypass pipe. When the gate or gate plate is damaged, causing blockage of the device, or when the equipment is damaged and needs repair, the water in the wastewater inlet area can be discharged through the bypass pipe. Alternatively, when the inlet water quality is good and does not require treatment, the inlet water can be directly discharged through the bypass pipe. The flow regulator is used to ensure the stability of the water flow velocity.

[0023] The ultrasonic radiation zone is equipped with a drain pipe, an ultrasonic transducer, a power distribution cabinet, an ultrasonic generator, and a water level monitor. A butterfly valve is installed on the drain pipe. The ultrasonic generator can convert mains power into a high-frequency AC signal that matches the ultrasonic transducer, driving the ultrasonic transducer to work. The ultrasonic transducer can generate at least three different ultrasonic frequencies: 60kHz, 430kHz, and 1120kHz. When the ultrasonic equipment malfunctions, the sewage in the ultrasonic radiation zone can be discharged through the drain pipe at the bottom for quick repair.

[0024] A gate is installed between the sewage inlet area and the ultrasonic radiation area to control the water flow;

[0025] The peracetic acid reaction zone is equipped with a water level controller, an automatic dosing tank, a stirrer, and a water outlet pipe. A circular gate III is installed on the water outlet pipe. The stirrer is used to fully mix the peracetic acid solution and wastewater in the reaction zone, and the automatic dosing tank is used to add a peracetic acid solution of appropriate concentration to the reaction zone.

[0026] A hydraulic controller and a power distribution cabinet connected to the hydraulic controller are provided between the ultrasonic radiation zone and the peracetic acid reaction zone. The water level controller of the peracetic acid reaction zone and the water level monitor of the ultrasonic radiation zone are both electrically connected to the hydraulic controller.

[0027] Compared with the prior art, the present invention has the following advantages and technical effects:

[0028] 1. Ultrasound and peracetic acid exhibit excellent synergistic bactericidal effects. Ultrasonic radiation generates numerous cavitation bubbles. The enormous energy released by the collapse of these cavitation bubbles is sufficient to cause water molecules (radiolysis) to split into hydroxyl radicals (OH·) and hydrogen atoms (H·). These highly reactive intermediates inactivate pathogenic microorganisms by attacking their cell walls and membranes. The rupture of cavitation bubbles triggers enormous shear forces, instantaneous high temperatures, and high pressures, directly impacting the cell structure. Pathogenic bacterial cell aggregates attached to solid impurities are dispersed into single-cell states, reducing the cells' resistance to chemical disinfectants and facilitating further inactivation. On the other hand, ultrasonic radiation effectively disrupts the cell membranes of pathogenic bacteria, allowing peracetic acid to directly penetrate the damaged cell membrane or diffuse into the cell, acting on intracellular substances and further inactivating the pathogens.

[0029] 2. The synergistic sterilization technology of ultrasound and peracetic acid can effectively reduce the energy consumption and time cost of ultrasound sterilization alone, providing a technical reference for the large-scale and widespread application of ultrasound sterilization. At the same time, the ultrasound and peracetic acid sterilization technology does not produce disinfection byproducts and does not cause secondary pollution, making it a highly efficient and environmentally friendly disinfection technology.

[0030] 3. The ultrasonic-enhanced peracetic acid disinfection device can be adjusted in size to accommodate the inactivation of pathogens in various wastewaters, such as hospital wastewater, domestic sewage, and aquaculture wastewater. Ideally, the device can be manually moved to different locations, such as residential buildings, commercial buildings, hospitals, warehouses, and sewage treatment plants, to achieve rapid disinfection of different wastewater types. This integrated device can significantly reduce the risk of waterborne pathogens and effectively avoid the problems of toxic byproducts and high energy consumption associated with traditional disinfection methods. Attached Figure Description

[0031] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 This is a schematic diagram of the device for inactivating pathogenic microorganisms in water by sound-enhanced peracetic acid according to the present invention;

[0033] Figure 2 This is a top view of the device for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid according to the present invention.

[0034] Figure 3 This is a cross-sectional view of the device for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid according to the present invention.

[0035] Figure 4 The effect of ultrasound-enhanced peracetic acid treatment on the morphology of Escherichia coli cells;

[0036] Figure 5 The effects of treatment with separate ultrasound, separate peracetic acid, and an integrated ultrasound-enhanced peracetic acid treatment device on E. coli protein in water were investigated.

[0037] Figure 6 The effect of pH on the inactivation of Escherichia coli in water by an integrated ultrasonic-enhanced peracetic acid device;

[0038] Figure 7 The effect of temperature on the inactivation of Escherichia coli in water by an integrated ultrasonic-enhanced peracetic acid device;

[0039] Figure 8 To improve the efficiency of ultrasonic-enhanced peracetic acid integrated device in inactivating Escherichia coli in actual wastewater;

[0040] The components are as follows: 1. Inlet pipe; 2. Circular gate I; 3. Flow regulator; 4. Bypass pipe; 5. Circular gate II; 6. Gate plate; 7. Drain pipe; 8. Ultrasonic transducer; 9. Power distribution cabinet; 10. Ultrasonic generator; 11. Water level monitor; 12. Hydraulic controller; 13. Water level controller; 14. Automatic dosing tank; 15. Agitator; 16. Outlet pipe; 17. Circular gate III; 18. Butterfly valve. Detailed Implementation

[0041] It should be noted that, unless otherwise specified, the embodiments and features described in this invention can be combined with each other. The described embodiments are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this invention. The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0042] This invention provides a method and apparatus for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid, comprising the following steps:

[0043] Insoluble impurities in wastewater are removed through sedimentation.

[0044] Wastewater is treated with ultrasonic radiation to disperse aggregated pathogenic microorganisms into single-cell states. The ultrasonic radiation treatment involves at least two frequencies of ultrasound. When wastewater is treated with ultrasonic radiation of different frequencies, aggregated pathogenic microorganisms in the water are dispersed into single-cell states, the cell membranes are destroyed, and the resistance of pathogenic microorganisms to chemical disinfectants is significantly reduced.

[0045] A strong oxidant is added to the wastewater that has been treated with ultrasonic radiation, and the mixture is stirred with a stirrer 15 to inactivate pathogenic microorganisms in the wastewater. The strong oxidant is a peracetic acid solution. The peracetic acid solution is used to inactivate pathogenic microorganisms in the wastewater. Peracetic acid enters the cell through molecular diffusion and direct penetration through the damaged cell membrane, oxidizing the substances inside the cell and further inactivating the pathogenic microorganisms in the water.

[0046] Furthermore, ultrasonic radiation treatment also includes:

[0047] Low-frequency ultrasonic waves are arranged below the sewage surface. The low-frequency ultrasonic waves use probe-type ultrasonic transducers and are arranged vertically below the sewage surface.

[0048] High-frequency ultrasonic waves are placed at the bottom of the wastewater. The high-frequency ultrasonic waves use planar ultrasonic transducers and are horizontally arranged at the bottom of the solution.

[0049] Furthermore, the sedimentation time should be no less than 10 minutes.

[0050] Furthermore, the ultrasonic radiation treatment time shall not be less than 10 minutes.

[0051] Furthermore, ultrasonic radiation treatment also includes:

[0052] The ultrasonic generator outputs a sinusoidal signal for conversion into ultrasonic waves, and the power density of the ultrasonic generator is not less than 0.038 W / mL.

[0053] Furthermore, ultrasonic radiation treatment also includes:

[0054] Low-frequency ultrasonic waves are positioned 2 cm below the surface of the wastewater.

[0055] Furthermore, the concentration of peracetic acid in the wastewater is not less than 26 μM.

[0056] Furthermore, the mass fraction of peracetic acid in the peracetic acid solution is not less than 18.04%.

[0057] Furthermore, the peracetic acid solution also contains hydrogen peroxide, with a mass fraction of not less than 12%.

[0058] Furthermore, the agitator 15 should rotate at a speed of no less than 150 rpm to ensure thorough mixing of pathogenic microorganisms in the water with peracetic acid.

[0059] The present invention also provides a device for inactivating pathogenic microorganisms in water by sound wave enhanced peracetic acid, comprising a sewage inlet zone, an ultrasonic radiation zone and a peracetic acid reaction zone connected in sequence.

[0060] The sewage inlet area is equipped with an inlet pipe 1, a flow regulator 3, and a bypass pipe 4 located at the bottom of the sewage inlet area. A circular gate I2 is installed on the inlet pipe 1, and a circular gate II5 is installed on the bypass pipe 4. When the gate or gate plate is damaged, causing blockage of the device, or when the equipment is damaged and needs repair, the water in the sewage inlet area can be discharged through the bypass pipe 4. Alternatively, when the inlet water quality is good and does not require treatment, the inlet water can be directly discharged through the bypass pipe. The flow regulator 3 is used to ensure the stability of the water flow velocity.

[0061] The ultrasonic radiation zone is equipped with a drain pipe 7, an ultrasonic transducer 8, a power distribution cabinet 9, an ultrasonic generator 10, and a water level monitor 11. A butterfly valve 18 is installed on the drain pipe 7. The ultrasonic generator 10 can convert mains power into a high-frequency AC signal that matches the ultrasonic transducer 8, driving the ultrasonic transducer 8 to work. The ultrasonic transducer 8 can generate at least three different ultrasonic frequencies: 60kHz, 430kHz, and 1120kHz. When the ultrasonic equipment malfunctions, the sewage in the ultrasonic radiation zone can be discharged through the drain pipe 7 at the bottom for quick repair.

[0062] A gate 6 is installed between the sewage inlet area and the ultrasonic radiation area to control the water flow;

[0063] The peracetic acid reaction zone is equipped with a water level controller 13, an automatic dosing tank 14, a stirrer 15, and an outlet pipe 16. A circular gate Ⅲ 17 is installed on the outlet pipe 16. The stirrer 15 is used to fully mix the peracetic acid solution and sewage in the peracetic acid reaction zone. The automatic dosing tank 14 is used to add a peracetic acid solution of appropriate concentration to the peracetic acid reaction zone.

[0064] A hydraulic controller 12 and a power distribution cabinet 9 connected to the hydraulic controller 12 are provided between the ultrasonic radiation zone and the peracetic acid reaction zone. The water level controller 13 of the peracetic acid reaction zone and the water level monitor 11 of the ultrasonic radiation zone are both electrically connected to the hydraulic controller 12.

[0065] The wastewater to be disinfected first enters the wastewater inlet zone, where insoluble solid particles are removed by sedimentation. After sedimentation, the wastewater enters the ultrasonic radiation zone, where the ultrasonic generator 10 controls the ultrasonic transducer 8 to generate ultrasonic waves of different frequencies and powers, subjecting the wastewater to ultrasonic treatment for at least 10 minutes. The ultrasonically treated wastewater then enters the peracetic acid reaction zone, where the automatic dosing tank 14 adds a peracetic acid solution of appropriate concentration according to a set flow rate. The peracetic acid reaction zone is equipped with a stirrer 15, which further inactivates the ultrasonically treated pathogens for at least 10 minutes under thorough mixing. After a period of reaction, the wastewater is discharged from the peracetic acid reaction zone through the outlet pipe 16.

[0066] The device for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid provided by this invention has the following specific startup steps:

[0067] Wastewater to be disinfected enters the wastewater inlet area through inlet pipe 1, passes through flow buffer 3 and gate 6, and then enters ultrasonic transducer 8. Flow buffer 3 regulates the inlet water flow, ensuring uniform flow and stable velocity. A circular gate I2 installed on inlet pipe 1 controls the inlet flow rate. A bypass pipe 4 is located at the bottom of the wastewater inlet area, equipped with a circular gate II5. When the gate or gate 6 is damaged, causing blockage or requiring equipment repair, water can be discharged through bypass pipe 4. Alternatively, when the inlet water quality is good and does not require treatment, it can be directly discharged through bypass pipe 4. Ultrasonic transducer 8 is controlled and regulated by ultrasonic generator 10 and powered by distribution cabinet 9. Ultrasonic transducer 8 can be customized based on parameters such as ultrasonic frequency range, hydraulic residence time, and treatment flow rate. A drain pipe 7 is located at the bottom of the ultrasonic radiation area, and a butterfly valve 18 is installed on the drain pipe 7. The ultrasonically treated water flows through water level controller 13 into the peracetic acid reaction area. The hydraulic controller 12 controls the water level controller 13 by monitoring the water level through the water level monitor 11, thereby regulating the water level in the peracetic acid reaction zone. In the peracetic acid reaction zone, the peracetic acid solution is added to the reaction zone by the automatic dosing tank 14, and then stirred and mixed by the stirrer 15 to ensure a complete reaction. The size of the reaction zone is determined based on the hydraulic residence time of the wastewater in the peracetic acid reaction zone. The treated water is finally discharged from the device through the outlet pipe 16. A circular gate Ⅲ17 is installed at the outlet pipe 16. All electrical instruments in the device are powered by the distribution cabinet 9.

[0068] Example 1:

[0069] To investigate the inactivation effect of ultrasound combined with peracetic acid, *E. coli* suspensions were divided into different groups, each with a volume of 500 mL. Before sterilization, the volume of *E. coli* cell suspension added to the reactor was determined by measuring the absorbance at 600 nm to achieve a consistent initial cell concentration of (1.3–1.6) × 10⁻⁶. 7 CFUmL -1 In the case of sonication alone, the *E. coli* suspension enters the wastewater inlet zone, and then from there enters the ultrasonic radiation zone, where it is treated with different frequencies (60kHz, 430kHz, 1120kHz) for 10 minutes. In the case of peracetic acid alone, the *E. coli* suspension is added to the peracetic acid reaction zone, where peracetic acid solution is added using the automatic dosing tank, and the suspension is treated for 10 minutes. In the case of ultrasound-enhanced peracetic acid treatment, the *E. coli* suspension first enters the wastewater inlet zone, and then from there enters the ultrasonic radiation zone, where it is treated with different frequencies (60kHz, 430kHz, 1120kHz) for 10 minutes. The sonicated *E. coli* suspension then enters the peracetic acid reaction zone, where it is further treated with peracetic acid for another 10 minutes. The concentration of peracetic acid (PAA) during the treatment is 26 μM.

[0070] Table 1 shows that sonication alone at different frequencies (60kHz, 430kHz, and 1120kHz) for 10 min resulted in poor inactivation of *E. coli*, with inactivations of only 0.13-log, 0.09-log, and 0.16-log, respectively. In contrast, peracetic acid alone for 10 min achieved an inactivation rate of 2.29-log for *E. coli*. The excellent disinfection effect of peracetic acid alone is mainly due to its ability to oxidize sulfhydryl groups (-SH) and disulfide bonds (SS) in proteins and enzymes, causing significant functional disorders in the cell membrane and intracellular environment, ultimately leading to apoptosis of the pathogenic bacteria. Compared to sonication alone or peracetic acid alone, pretreatment with sonication at different frequencies (60kHz, 430kHz, and 1120kHz) for 10 min, followed by further treatment with peracetic acid for 10 min, significantly improved the inactivation efficiency of *E. coli*, reaching 4.69-log, 4.1-log, and 4.06-log, respectively. It can be observed that although ultrasound radiation alone has a poor inactivation effect on E. coli in a short period of time, E. coli cells are more dispersed after ultrasound pretreatment, cell membranes are perforated and cell contents leak out, making E. coli more sensitive to peracetic acid and further improving the bactericidal effect of peracetic acid.

[0071] Example 2:

[0072] The volume of E. coli cell suspension added to the reactor was determined by measuring the absorbance at 600 nm to achieve an initial cell concentration of (1.3–1.6) × 10⁻⁶.7 CFUmL -1 500 mL of E. coli bacterial solution first enters the wastewater inlet zone, then the ultrasonic radiation zone. The ultrasonic generator 10 is turned on and adjusted to the 60 kHz ultrasonic frequency band. The electrical signal generated by the ultrasonic generator 10 is transmitted to the ultrasonic transducer 8, which converts the electrical signal into 60 kHz ultrasound. The E. coli bacterial solution is treated with 60 kHz low-frequency ultrasound in the ultrasonic radiation zone for 10 minutes. After ultrasonic treatment, the E. coli bacterial solution enters the peracetic acid reaction zone. In the peracetic acid reaction zone, the stirrer 15 and the automatic dosing tank 14 are turned on, and peracetic acid is added to the reaction zone. Under the stirring action of the stirrer 15, the peracetic acid in the wastewater and E. coli come into full contact. After the E. coli bacterial solution is treated in the peracetic acid reaction zone for 10 minutes, a water sample is collected. The changes in the microscopic morphology of E. coli cells in the water sample are analyzed using transmission electron microscopy and scanning electron microscopy. The concentration of peracetic acid in the peracetic acid reaction zone is 26 μM.

[0073] Scanning electron microscopy (SEM) was used to observe the changes in the micromorphology of *E. coli* before and after different treatments. For example... Figure 4 As shown, untreated *E. coli* possesses uniform, smooth, and intact rod-shaped cells with a clear and plump microstructure. After treatment with ultrasound-enhanced peracetic acid (60 kHz → PAA), the surface of *E. coli* cells exhibited a certain degree of indentation, including cell collapse, cell surface perforation, and rupture of the outer wall. The results indicate that ultrasound-enhanced peracetic acid (60 kHz → PAA) treatment can effectively disrupt the cell structure of *E. coli*.

[0074] Similarly, transmission electron microscopy was used to further analyze the effect of ultrasound-enhanced peracetic acid (60 kHz → PAA) treatment on the morphology of *E. coli* cells. Figure 4 As shown, untreated E. coli cells have normal cell structure and clear cell membrane structure. E. coli cells treated with ultrasound-enhanced peracetic acid (60kHz→PAA) showed significant changes, including blurred cell membranes and leakage of cell contents. This result further confirms that ultrasound-enhanced peracetic acid (60kHz→PAA) treatment can effectively kill E. coli by disrupting cell structure.

[0075] Example 3:

[0076] The volume of E. coli cell suspension added to the reactor was determined by measuring the absorbance at 600 nm to achieve an initial cell concentration of (1.3–1.6) × 10⁻⁶. 7 CFUmL -1500 mL of E. coli bacterial solution first enters the wastewater inlet zone, then from there into the ultrasonic radiation zone. The ultrasonic generator 10 is activated and adjusted to a 60 kHz ultrasonic frequency. The electrical signal generated by the ultrasonic generator 10 is transmitted to the ultrasonic transducer 8, which converts the signal into 60 kHz ultrasound. The E. coli bacterial solution is treated in the ultrasonic radiation zone for 10 minutes. The ultrasonically treated E. coli sample is then collected and stored at 4°C for analysis. The ultrasonically treated E. coli bacterial solution then enters the peracetic acid reaction zone. In the peracetic acid reaction zone, the stirrer 15 and the automatic dosing tank 14 are activated. Peracetic acid is added to the reaction zone, and under the stirring action of the stirrer 15, the peracetic acid in the wastewater and E. coli come into full contact. After the E. coli bacterial solution is treated in the peracetic acid reaction zone for 10 minutes, a water sample is collected. Additionally, the cell concentration is (1.3–1.6) × 10⁻⁶. 7 CFUmL -1 E. coli was added to the peracetic acid reaction zone and treated with peracetic acid for 10 min. Samples were then taken and stored at 4°C for analysis. The concentration of peracetic acid (PAA) in the PAA reaction zone was 26 μM. The concentration of E. coli protein in the samples was determined using a protein assay kit.

[0077] A protein concentration assay kit was used to determine changes in E. coli protein levels before and after sterilization. For example... Figure 5 As shown, compared with the untreated group, the protein concentration of E. coli treated with ultrasound alone increased from 0.27 mg / mL. -1 Decreased to 0.25 mg / mL -1 The protein content in the ultrasound-treated group was significantly different from that in the control group (p < 0.05). Peracetic acid treatment alone also significantly reduced the intracellular protein content of E. coli, and the protein concentration was significantly different from that in the untreated group (p < 0.05). Notably, ultrasound-enhanced peracetic acid (60 kHz → PAA) treatment significantly reduced the protein concentration in E. coli.

[0078] Example 4:

[0079] To investigate the effect of different pH values ​​on the inactivation of *E. coli* by ultrasound-enhanced peracetic acid (US→PAA), the absorbance of the bacterial suspension was measured at 600 nm to determine the volume of cell suspension added to the reactor, ensuring an initial cell concentration of (1.3–1.6) × 10⁻⁶. 7 CFUmL -1The pH of the bacterial suspension was adjusted to 3, 5, 7, and 10, with a volume of 500 mL for each suspension. The 500 mL E. coli suspensions at different pH values ​​first entered the wastewater inlet zone, then from there into the ultrasonic radiation zone. The ultrasonic generator 10 was activated and adjusted to the 60 kHz ultrasonic frequency band. The electrical signal generated by the ultrasonic generator 10 was transmitted to the ultrasonic transducer 8, which converted the signal into 60 kHz ultrasound waves. The E. coli suspension was then treated with 60 kHz ultrasound in the ultrasonic radiation zone for 10 minutes. After ultrasonic treatment, the E. coli suspension entered the peracetic acid reaction zone. In the peracetic acid reaction zone, the stirrer 15 and automatic dosing tank 14 were turned on, and peracetic acid was added to the reaction zone. Under the stirring action of the stirrer 15, the peracetic acid in the wastewater and E. coli came into full contact. The E. coli bacterial solution was treated in the peracetic acid reaction zone for 10 minutes. Water samples were collected after treatment, and the plate count method was used to evaluate the inactivation effect of ultrasonic-enhanced peracetic acid (60kHz→PAA) treatment on E. coli under different pH conditions. The concentration of peracetic acid in the peracetic acid reaction zone was 26μM.

[0080] This example demonstrates the inactivation of *E. coli* by ultrasound-enhanced peracetic acid (US→PAA) at different pH values. Figure 6 It was found that under acidic conditions (pH < 7), ultrasound-enhanced peracetic acid (US→PAA) treatment showed a high inactivation efficiency for *E. coli*, exceeding 4-log. At pH > 7, the inactivation effect of ultrasound-enhanced peracetic acid (US→PAA) treatment on *E. coli* was significantly reduced. The results indicate that under acidic conditions, ultrasound-enhanced peracetic acid (60 kHz→PAA) treatment has a better inactivation effect on *E. coli*.

[0081] Example 5:

[0082] To investigate the effect of different temperatures on the inactivation of *E. coli* by ultrasound-enhanced peracetic acid (US→PAA), the absorbance of the bacterial suspension was measured at 600 nm to determine the volume of cell suspension added to the reactor, ensuring an initial cell concentration of (1.3–1.6) × 10⁻⁶. 7 CFUmL -1The temperatures of the bacterial suspensions were adjusted to 5℃, 10℃, 25℃, and 38℃, with a volume of 500mL for each suspension. The 500mL E. coli suspensions at different pH values ​​first entered the wastewater inlet zone, then proceeded to the ultrasonic radiation zone. The ultrasonic generator 10 was activated and adjusted to the 60kHz ultrasonic frequency band. The electrical signal generated by the ultrasonic generator 10 was transmitted to the ultrasonic transducer 8, which converted the signal into 60kHz ultrasound waves. The E. coli suspension was treated in the ultrasonic radiation zone for 10 minutes. After ultrasonic treatment, the E. coli suspension entered the peracetic acid reaction zone. In the peracetic acid reaction zone, the stirrer 15 and automatic dosing tank 14 were turned on, and peracetic acid was added to the reaction zone. Under the stirring action of the stirrer 15, the peracetic acid in the wastewater and E. coli came into full contact. The E. coli bacterial solution was treated in the peracetic acid reaction zone for 10 minutes. Water samples were collected after treatment, and the inactivation effect of ultrasonic-enhanced peracetic acid treatment (US→PAA) on E. coli under different pH conditions was calculated using the plate count method. The concentration of peracetic acid in the peracetic acid reaction zone was 26 μM.

[0083] The inactivation effect of peracetic acid on bacteria increases with increasing temperature. This case study investigated the effect of ultrasound-enhanced peracetic acid (60 kHz → PAA) system on the inactivation of *E. coli* at different temperatures. Figure 7 As shown, the inactivation energy of ultrasound-enhanced peracetic acid (60 kHz → PAA) treatment on *E. coli* increased from 1.84 log₂O₅ to 4.99 log₂O₅ as the temperature increased from 5 °C to 38 °C. Peracetic acid can be produced at higher temperatures. 1 O2, 1 O2 promotes the inactivation of E. coli. In addition, the disruptive effect of ultrasound pretreatment can reduce the cell's resistance to peracetic acid by damaging the cell membrane, thereby enhancing the inactivation effect of peracetic acid.

[0084] Example 6:

[0085] Using ultrapure water, untreated influent from a wastewater treatment plant, secondary effluent, and tertiary effluent as examples, this study investigated the inactivation effect of ultrasonically enhanced peracetic acid (60 kHz → PAA) on *E. coli* in different water qualities. Considering the complexity of the microbial composition in real wastewater, the wastewater was autoclaved for 20 minutes to eliminate the influence of the original microorganisms. The absorbance of the bacterial suspension was measured at 600 nm to determine the volume of cell suspension added to different water qualities, aiming to achieve an initial cell concentration of (1.3–1.6) × 10⁻⁶. 7 CFUmL -1500 mL of water containing different types of E. coli first entered the ultrasonic radiation zone. The ultrasonic generator 10 was turned on and adjusted to the 60 kHz ultrasonic frequency band. The electrical signal generated by the ultrasonic generator 10 was transmitted to the ultrasonic transducer 8, which converted the electrical signal into 60 kHz ultrasonic waves. The wastewater first entered the wastewater inlet zone, and then from there entered the ultrasonic radiation zone for 60 kHz ultrasonic treatment for 10 minutes. The ultrasonically treated wastewater then entered the peracetic acid reaction zone. In the peracetic acid reaction zone, the stirrer 15 and the automatic dosing tank 14 were turned on, and peracetic acid was added to the reaction zone. Under the stirring action of the stirrer 15, the peracetic acid and E. coli in the wastewater came into full contact. The wastewater was treated in the peracetic acid reaction zone for 10 minutes. Water samples were collected after treatment, and the plate count method was used to evaluate the inactivation effect of ultrasonic-enhanced peracetic acid (US→PAA) treatment on E. coli in different water types. In the peracetic acid reaction zone, the concentration of peracetic acid was 26 μM.

[0086] like Figure 8 As shown, the inactivation energy of ultrasound-enhanced peracetic acid (US→PAA) treatment in ultrapure water was the highest among all water matrices, at 4.67-log. The inactivation energy of ultrasound-enhanced peracetic acid (US→PAA) treatment for tertiary effluent from wastewater treatment plants was reduced by 25.05% compared to ultrapure water. Compared to ultrapure water, the disinfection performance of ultrasound-enhanced peracetic acid (US→PAA) treatment for secondary effluent decreased by 51.39%, with the lowest disinfection performance in untreated effluent at 0.49-log. Previous studies have also shown that the disinfection performance of peracetic acid is easily affected by matrices such as organic matter, inorganic particles, and suspended solids in water. Higher COD content in actual wastewater indicates more severe organic pollution, which seriously affects the inactivation efficiency of ultrasound-enhanced peracetic acid (US→PAA) treatment (60kHz→PAA) for E. coli in actual wastewater. The above results show that the typical inactivation order is: ultrapure water > tertiary effluent > secondary effluent > untreated influent.

[0087] Table 1 shows the inactivation efficiencies of ultrasound alone, peracetic acid alone, and ultrasound-enhanced peracetic acid treatment on Escherichia coli in water.

[0088]

[0089] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid, characterized in that, Includes the following steps: Insoluble impurities in wastewater are removed through sedimentation. Wastewater is subjected to ultrasonic radiation treatment to disperse aggregated pathogenic microorganisms in the wastewater into single-cell states, wherein the ultrasonic radiation treatment includes at least two frequencies of ultrasound. A strong oxidant is added to the wastewater that has been treated with ultrasonic radiation, and the mixture is stirred to inactivate pathogenic microorganisms in the wastewater. The strong oxidant is a peracetic acid solution, the concentration of peracetic acid in the wastewater is not less than 26 μM, and the mass fraction of peracetic acid in the peracetic acid solution is not less than 18.04%. The ultrasonic radiation treatment also includes: Low-frequency ultrasonic waves are deployed below the sewage surface; High-frequency ultrasonic waves are placed at the bottom of the sewage.

2. The method for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid according to claim 1, characterized in that, The precipitation time shall not be less than 10 minutes.

3. The method for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid according to claim 1, characterized in that, The duration of the ultrasonic radiation treatment shall not be less than 10 minutes.

4. The method for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid according to claim 1, characterized in that, The ultrasonic radiation treatment also includes: A sinusoidal signal for conversion into ultrasound is output by an ultrasonic generator (10), the power density of which is not less than 0.038 W / mL.

5. The method for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid according to claim 1, characterized in that, The ultrasonic radiation treatment also includes: Low-frequency ultrasonic waves are positioned 2 cm below the surface of the wastewater.

6. An apparatus for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid, applied to the method for inactivating pathogenic microorganisms in water using sound-enhanced peracetic acid as described in any one of claims 1-5, characterized in that, It includes a wastewater inlet zone, an ultrasonic radiation zone, and a peracetic acid reaction zone that are connected in sequence; The sewage inlet area is provided with an inlet pipe (1), a flow buffer (3) and a bypass pipe (4) located at the bottom of the sewage inlet area. A circular gate I (2) is installed on the inlet pipe (1) and a circular gate II (5) is installed on the bypass pipe (4). The ultrasonic radiation zone is equipped with a drain pipe (7), an ultrasonic transducer (8), a power distribution cabinet (9), an ultrasonic generator (10), and a water level monitor (11). A butterfly valve (18) is installed on the drain pipe (7). A gate (6) is installed between the sewage inlet area and the ultrasonic radiation area; The peracetic acid reaction zone is equipped with a water level controller (13), an automatic dosing tank (14), a stirrer (15) and a water outlet pipe (16), and a circular gate III (17) is installed on the water outlet pipe (16); A hydraulic controller (12) and a power distribution cabinet (9) connected to the hydraulic controller (12) are provided between the ultrasonic radiation zone and the peracetic acid reaction zone. The water level controller (13) of the peracetic acid reaction zone and the water level monitor (11) of the ultrasonic radiation zone are both electrically connected to the hydraulic controller (12).

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