Spiral flow channel plug flow type electrochemical disinfection device and disinfection method

Abstract

The invention relates to a spiral flow channel plug flow type electrochemical disinfection device and a disinfection method.The device comprises an inlet and outlet component provided with an inlet and an outlet, concentric tubular negative and positive electrodes are arranged between the inlet and the outlet, and the concentric tubular negative and positive electrodes are arranged in pairs and connected with a power source respectively; and a spiral flow channel structure is additionally arranged between the concentric tubular cathode and anode to promote turbulent flow. After the spiral flow channel is added, the flowing state in the flow channel can be improved, the shearing force and mixing in the fluid are increased, fluid generation is facilitated, the turbulence intensity is enhanced, laminar flow areas and dead zones in the fluid are effectively reduced, and the mixing and mass transfer performance of a whole flow field is improved.

Description

Technical Field

[0001] The present invention relates to the field of fluid sterilization, and in particular to a spiral flow channel push-flow electrochemical disinfection device and a disinfection method based on 3D printing. Background Art

[0002] In recent years, electrochemical disinfection has become a research hotspot as an efficient and safe method. Compared with traditional disinfection methods such as chlorine disinfection, ultraviolet disinfection and ozone disinfection, the electrochemical disinfection process does not require the addition of chemical agents, and has the advantages of high automation, strong controllability, multiple functions, high efficiency, small footprint, and strong environmental adaptability. Currently, common electrochemical disinfection devices include complete mixing, filtration and plug flow types. For example, CN213171603U discloses a three-dimensional electrochemical disinfection device with a synergistic effect, CN115768730A discloses a system and method for electrochemical disinfection, CN101746857A discloses a method and equipment for electrochemical disinfection of water, and CN1485282A discloses electrochemical disinfection technology and devices for bacterial sewage.

[0003] However, the distance between electrodes in a hybrid reactor is relatively large, which leads to problems such as long disinfection cycle, high energy consumption, and poor disinfection effect. Filtration reactors have problems with electrode degradation and electrode blockage caused by microorganisms or other substances in actual water. A plug flow reactor in which the water flow direction is parallel to the electrode plate can solve the problem of low mass transfer rate in a completely hybrid reactor. A water pump is used to allow water to flow continuously through the electrode plate, thereby ensuring that microorganisms are in uniform and stable contact with the electrode. It can also avoid the problem of electrode blockage in a filtration reactor, and can solve problems such as the upper limit of mass transfer by further optimizing the reactor configuration. Therefore, the plug flow electrochemical disinfection device has obvious advantages over the completely hybrid and filtration types.

[0004] Conventional plug-flow electrochemical disinfection devices also have shortcomings, such as low turbulence intensity and dead zones between electrodes and flow channels, which affect their disinfection effects. Summary of the invention

[0005] In view of the above-mentioned state of the prior art, the inventors of the present invention have conducted in-depth research in the field of electrochemical disinfection devices and found that the use of spiral flow channels between the cathode and anode in the electrochemical disinfection device can improve the turbulence intensity and mass transfer efficiency of the electrochemical disinfection device, thereby improving the disinfection effect and operational stability. At the same time, with the appropriate electrochemical disinfection process, a good electrochemical disinfection effect can be achieved. The present invention is completed based on the above-mentioned findings.

[0006] Therefore, one object of the present invention is to provide a spiral flow channel plug flow electrochemical disinfection device. The use of a cylindrical electrode structure combined with a spiral flow channel design can effectively improve the flow state inside the device from a fluid mechanics perspective, improve turbulence intensity and mass transfer efficiency, and improve the disinfection effect.

[0007] The second invention objective of the present invention is to provide an electrochemical disinfection method based on the spiral flow channel plug flow electrochemical disinfection device, and further cooperate with a suitable electrochemical disinfection process to achieve a good electrochemical disinfection effect.

[0008] The technical solution for achieving the above-mentioned invention object can be summarized as follows:

[0009] The spiral flow channel plug flow electrochemical disinfection device comprises: a cathode and an anode arranged in a concentric tubular shape, a spiral flow channel is arranged between the cathode and the anode, a feed component and a discharge component are respectively arranged at the bottom and the top of the cathode and the anode, the feed component is provided with a feed port, and the discharge component is provided with a discharge port.

[0010] According to the present invention, preferably, the spiral flow channel includes a spiral structure and a supporting structure arranged on the spiral structure.

[0011] According to the present invention, preferably, the cathode and the anode are both cylindrical structures, and more preferably, they are cylindrical structures made of metal; more preferably, the thickness of the cylindrical structure is 1-3 mm and the height is 130-180 mm.

[0012] According to the present invention, preferably, the anode is located outside, and further preferably, the inner diameter of the anode is 60-80 mm;

[0013] Preferably, the cathode is located inside, and further preferably, the inner diameter of the cathode is 40-60 mm.

[0014] According to the present invention, preferably, the distance between the cathode and the anode is the same as the width of the spiral structure, and further preferably the width is 10-20 mm.

[0015] According to the present invention, the spiral flow channel plug flow electrochemical disinfection device is used for electrochemical disinfection and sterilization; it is further preferably used for electrochemical disinfection and sterilization in the sewage treatment process.

[0016] According to the present invention, there is also provided an electrochemical disinfection method, comprising using the above-mentioned spiral flow channel plug flow electrochemical disinfection device, comprising the following steps:

[0017] The cathode and anode of the spiral flow channel plug flow electrochemical disinfection device are connected to the power supply respectively, the liquid to be treated enters the spiral flow channel plug flow electrochemical disinfection device through the feed inlet, the liquid flows along the spiral flow channel, and the power supply is started to electrochemically disinfect the liquid.

[0018] According to the present invention, preferably, the flow rate of the feed liquid to be treated at the feed inlet is ≤110 mL / min, and more preferably ≤100 mL / min.

[0019] According to the present invention, preferably, the voltage between the cathode and the anode is 2.8-3.6V.

[0020] According to the present invention, preferably, electrolytes are added to the liquid to be treated during the electrochemical disinfection process;

[0021] Preferably, the type of electrolyte is hydrochloride, more preferably sodium chloride;

[0022] Preferably, the concentration of electrolyte added is controlled to be 10-100 mmol / L.

[0023] Beneficial effects of the present invention:

[0024] 1. The flow channel between the anode and cathode in the electrochemical disinfection device of the present invention adopts a spiral flow channel, which improves the turbulence intensity and mass transfer efficiency of the electrochemical disinfection device, thereby improving the disinfection effect and operation stability.

[0025] 2. The addition of the spiral structure of the present invention makes the fluid flow trajectory tend to flow in the spiral structure, the speed of the spiral flow channel is increased to 10 times that of the flat flow channel, and the turbulence intensity distribution is also more uniform.

[0026] 3. The turbulence on the electrode surface of the spiral flow channel device of the present invention increases, and the turbulence intensity increases by more than 10 times compared with the flat flow channel. The dead zone between the electrode and the flow channel components is reduced, thereby improving the mass transfer efficiency of the device.

[0027] 4. The inactivation rate of E. coli by the spiral flow channel disinfection device of the present invention is higher than that of the flat flow channel disinfection device, and the sterilization effect is better than that of the flat flow channel. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic diagram of the main structure of the spiral flow channel plug flow type electrochemical disinfection device of the present invention.

[0029] Figure 2 It is a three-dimensional schematic diagram of the longitudinal section of the spiral flow channel plug flow type electrochemical disinfection device of the present invention.

[0030] Figure 3 It is a schematic diagram of the structure of the spiral flow channel in the spiral flow channel plug-flow electrochemical disinfection device of the present invention.

[0031] Figure 4 It is a schematic diagram of the structure of the positive and negative electrodes in the spiral flow channel plug flow electrochemical disinfection device of the present invention.

[0032] Figure 5 It is a schematic diagram of the structure of the feeding component in the spiral flow channel plug flow type electrochemical disinfection device of the present invention.

[0033] Figure 6 It is a three-dimensional schematic diagram of the feeding component in the spiral flow channel plug flow type electrochemical disinfection device of the present invention.

[0034] Figure 7 It is a schematic diagram of the main structure of a plug-flow electrochemical disinfection device without a spiral flow channel according to a comparative example of the present invention.

[0035] Figure 8 It is a three-dimensional schematic diagram of the longitudinal interface of a plug-flow electrochemical disinfection device without a spiral flow channel according to a comparative example of the present invention.

[0036] Fig. 9 Schematic diagram of the structure of the experimental device used in the test example of the present invention.

[0037] Fig.10 This is a diagram showing the effect of voltage change on the disinfection effect of the two devices in Experimental Example 1.

[0038] Fig.11 This is the effect of voltage on the disinfection effect of the two disinfection devices after adding electrolyte in Experimental Example 1.

[0039] Fig.12 This is the sterilization rate diagram after adding sodium thiosulfate in Test Example 2.

[0040] Fig.13 This is a diagram showing the effect of flow rate on the disinfection efficiency of two disinfection devices in Experimental Example 3.

[0041] Fig.14 This is a diagram of the sterilization effect of electrolytic Na2SO4 in Experimental Example 4.

[0042] Fig.15 This is a graph showing the current changes under 10 mM NaCl conditions in Experimental Example 5.

[0043] Fig.16 This is a graph showing the current changes under 100 mM NaCl conditions in Experimental Example 5.

[0044] Fig.17 This is a graph showing the change in E. coli concentration during storage after disinfection in Experimental Example 6.

[0045] Fig.18 This is a graph showing the survival percentage of E. coli during storage after disinfection in Experimental Example 6.

[0046] Fig.19This is the disinfection characteristic diagram of the disinfection device in Test Example 7 when it is running for a long time.

[0047] Fig. 20 This is a graph showing the current changes during long-term operation of the disinfection device in Test Example 7.

[0048] Wherein: 1. cathode, 2. anode, 3. spiral flow channel, 301. spiral structure, 302. support structure, 4. feed component, 401. feed port, 5. discharge component, 501. discharge port. DETAILED DESCRIPTION

[0049] The present invention provides a spiral flow channel plug flow electrochemical disinfection device and a disinfection method. Based on a cylindrical plug flow electrode, the present invention adopts 3D printing technology to manufacture a spiral flow channel between the cathode and anode of the disinfection device, optimizes the reactor configuration, improves the turbulence intensity and mass transfer efficiency of the reactor, and thus improves the disinfection effect and operation stability.

[0050] like Figure 1 , 2 As shown, the spiral flow channel plug flow electrochemical disinfection device of the present invention comprises: a cathode 1 and an anode 2 arranged in a concentric tubular shape, a spiral flow channel 3 is arranged between the cathode 1 and the anode 2, a feed component 4 and a discharge component 5 are respectively arranged at the bottom and the top of the cathode 1 and the anode 2, the feed component 4 is provided with a feed port 401, and the discharge component 5 is provided with a discharge port 501.

[0051] like Figure 3 As shown, in one or more preferred embodiments, the spiral flow channel 3 includes a spiral structure 301 and a support structure 302 disposed on the spiral structure 301. The support structure 302 can improve the strength and stability of the spiral structure 301.

[0052] In one or more preferred embodiments, the cathode 1 and the anode 2 are both cylindrical structures, and more preferably, they are cylindrical structures made of metal; more preferably, the thickness of the cylindrical structure is 1-3 mm and the height is 130-180 mm.

[0053] In one or more preferred embodiments, the anode 2 is located outside, and further preferably, the inner diameter of the anode 2 is 60-80 mm;

[0054] Preferably, the cathode 1 is located inside, and further preferably, the inner diameter of the cathode 1 is 40-60 mm.

[0055] In one or more preferred embodiments, the distance between the cathode 1 and the anode 2 is the same as the width of the spiral structure 301, and a further preferred width is 10-20 mm.

[0056] According to the present invention, the spiral flow channel plug flow electrochemical disinfection device is used for electrochemical disinfection and sterilization; it is further preferably used for electrochemical disinfection and sterilization in the sewage treatment process.

[0057] According to the present invention, there is also provided an electrochemical disinfection method, comprising using the above-mentioned spiral flow channel plug flow electrochemical disinfection device, comprising the following steps:

[0058] The cathode 1 and anode 2 of the spiral flow channel plug flow electrochemical disinfection device are connected to the power supply respectively, and the feed liquid to be treated enters the spiral flow channel plug flow electrochemical disinfection device through the feed inlet 401, and the feed liquid flows along the spiral flow channel 3, and the power supply is started to perform electrochemical disinfection on the feed liquid. The feed liquid after electrochemical disinfection is discharged from the discharge port 501.

[0059] In one or more preferred embodiments, the flow rate of the feed liquid to be treated at the feed inlet 401 is ≤110 mL / min, more preferably ≤100 mL / min, for example: 30 mL / min, 40 mL / min, 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 90 mL / min.

[0060] In one or more preferred embodiments, the voltage between the cathode 1 and the anode 2 is 2.8-3.6V, for example: 3V, 3.1V, 3.2V, 3.3V, 3.4V.

[0061] In one or more preferred embodiments, electrolytes are also added to the liquid to be treated during the electrochemical disinfection process;

[0062] Preferably, the type of electrolyte is hydrochloride, more preferably sodium chloride;

[0063] Preferably, the concentration of electrolyte added is controlled to be 10-100mmol / L, for example: 15mmol / L, 20mmol / L, 30mmol / L, 40mmol / L, 50mmol / L, 60mmol / L, 70mmol / L, 80mmol / L.

[0064] The present invention will be further described below through specific embodiments in conjunction with the accompanying drawings, but is not limited thereto.

[0065] Example 1

[0066] like Figure 1 , 2As shown, the spiral flow channel plug flow electrochemical disinfection device of the present invention comprises: a cathode 1 and an anode 2 arranged in a concentric tubular shape, a spiral flow channel 3 is arranged between the cathode 1 and the anode 2, a feed component 4 and a discharge component 5 are respectively arranged at the bottom and the top of the cathode 1 and the anode 2, the feed component 4 is provided with a feed port 401, and the discharge component 5 is provided with a discharge port 501.

[0067] like Figure 3 As shown, the spiral flow channel 3 includes a spiral structure 301 and a support structure 302 disposed on the spiral structure 301. The thickness of the single-turn spiral structure 301 is 3 mm and the width is 20 mm. The support structure 302 can improve the compressibility disadvantage of the spiral structure 301, and the support structure 302 is at the beginning of each turn.

[0068] like Figure 4 As shown, the cathode 1 and anode 2 described in this embodiment are both cylindrical structures, the thickness of the cylindrical structure is 1 mm, and the height is 130 mm. The cathode 1 is a pure titanium electrode, and the anode 2 is a titanium-based ruthenium-iridium electrode. The anode 2 is plated with a precious metal ruthenium-iridium layer by brush coating technology.

[0069] The anode 2 is located on the outside, and the inner diameter of the anode 2 is 60 mm; the cathode 1 is located on the inside, and the inner diameter of the cathode 1 is 40 mm. The distance between the cathode 1 and the anode 2 is the same as the width of the spiral structure 301, both of which are 20 mm.

[0070] Example 2

[0071] As described in Example 1, except that:

[0072] The cathode 1 and anode 2 are both cylindrical structures made of stainless steel, with a thickness of 3 mm and a height of 180 mm. The anode 2 is located on the outside, and the inner diameter of the anode 2 is 80 mm; the cathode 1 is located on the inside, and the inner diameter of the cathode 1 is 60 mm. The distance between the cathode 1 and the anode 2 is the same as the width of the spiral structure 301, both of which are 20 mm.

[0073] Example 3

[0074] As described in Example 1, except that:

[0075] The cathode 1 and anode 2 are both cylindrical structures made of stainless steel, with a thickness of 2 mm and a height of 170 mm. The anode 2 is located on the outside, and the inner diameter of the anode 2 is 70 mm; the cathode 1 is located on the inside, and the inner diameter of the cathode 1 is 60 mm. The distance between the cathode 1 and the anode 2 is the same as the width of the spiral structure 301, both of which are 10 mm.

[0076] Example 4

[0077] An electrochemical disinfection method, comprising using any one of the spiral flow channel plug flow electrochemical disinfection devices of Examples 1-3, comprising the following steps:

[0078] The cathode 1 and anode 2 of the spiral flow channel plug flow electrochemical disinfection device are connected to the power supply respectively, and the feed liquid to be treated enters the spiral flow channel plug flow electrochemical disinfection device through the feed inlet 401, and the feed liquid flows along the spiral flow channel 3, and the power supply is started to perform electrochemical disinfection on the feed liquid. The feed liquid after electrochemical disinfection is discharged from the discharge port 501.

[0079] In this embodiment, the flow rate of the liquid to be treated at the feed inlet 401 is 50 mL / min, and the voltage between the cathode 1 and the anode 2 is 3V.

[0080] Example 5

[0081] As described in Example 4, except that:

[0082] The flow rate of the treated liquid at the feed inlet 401 is 80 mL / min, and the voltage between the cathode 1 and the anode 2 is 3.2V.

[0083] Example 6

[0084] As described in Example 4, except that:

[0085] During the electrochemical disinfection process, electrolytes are added to the treated liquid. The type of electrolyte is sodium chloride, and the concentration of the electrolyte added is controlled to be 10 mmol / L.

[0086] Example 7

[0087] As described in Example 6, except that:

[0088] During the electrochemical disinfection process, electrolytes are added to the treated liquid. The type of electrolyte is sodium chloride, and the concentration of the electrolyte added is controlled to be 100 mmol / L.

[0089] Example 8

[0090] As described in Example 4, except that:

[0091] The flow rate of the treated liquid at the feed inlet 401 is 60 mL / min, and the voltage between the cathode 1 and the anode 2 is 3.4 V. During the electrochemical disinfection process, an electrolyte is added to the treated liquid, the type of the electrolyte is calcium chloride, and the concentration of the electrolyte added is controlled to be 50 mmol / L.

[0092] Comparative Example

[0093] As described in Example 1, except that:

[0094] like Figure 7 , 8As shown, no spiral flow channel 3 is provided between the cathode 1 and the anode 2 .

[0095] Test example

[0096] Use Fig. 9 The experimental device shown in the figure is used for the test, and the experimental device includes: a peristaltic pump, a power supply, an electrochemical disinfection device, and a container. One of the containers is filled with bacterial liquid, and connected to the electrochemical disinfection device through a peristaltic pump. The cathode and anode of the electrochemical disinfection device are respectively connected to the power supply, and the discharge port of the electrochemical disinfection device is connected to another container.

[0097] 1. Microbial culture

[0098] 1.1 Bacterial culture: Take out the frozen E. coli centrifuge tube from the -80℃ refrigerator, pick out the bacteria and inoculate them on the solid culture medium by streaking to obtain a single colony, shake and culture in a constant temperature incubator at 37℃ and 300r / min for 24 hours, and then place it in a 4℃ refrigerator for subsequent use. Take the cultured bacteria plate stored in the 4℃ refrigerator, pick out the colony at the end of the streaking and inoculate it into the sterile broth liquid culture medium, and shake and culture it at 37℃ and 300r / min for 24 hours.

[0099] 1.2 Self-prepared water sample: Transfer the bacterial solution to a 50mL sterile centrifuge tube, centrifuge at 8000rpm for 10min, discard the supernatant, add 20mL of high temperature sterilized 10mM NaCl solution, and resuspend. Repeat the centrifugation operation after the bacterial solution is resuspended. Repeat the above "resuspend-centrifuge" cleaning steps 2 to 3 times to obtain a bacterial suspension. Add the bacterial solution to a sterile 10mM NaCl solution, measure its absorbance (OD 600), and configure the initial concentration to be about 10 by concentration conversion. 6-7 The bacterial suspension with CFU / mL was used as the treated water sample. The conductivity of 10mM NaCl solution (1300-1500μS / cm) is close to the conductivity of the effluent from the reclaimed water plant. The concentration of bacteria was determined using the plate count method, and the plate was a sterilized nutrient agar medium.

[0100] 2. Disinfection experiment

[0101] 2.1 Test process

[0102] After assembling the disinfection device, use the peristaltic pump to adjust to the preset flow rate, pump the water sample to be treated into the disinfection device, connect the electrode to the power supply, adjust the preset voltage, wait for the liquid to fill the internal cavity of the device for 5-10 minutes and the current is stable, and then use a sterilized centrifuge tube to collect the water sample to determine the disinfection effect. Take out the water sample for plate counting. During the disinfection process, measure the parameters such as the current of the disinfection test solution and the concentration of active substances in the water.

[0103] 2.2 Bacterial plate count

[0104] After collecting the water sample, expose it to ultraviolet for 20 minutes and ventilate for 15 minutes. Perform aseptic operation, dilute the water sample with a 10-fold gradient using sterile saline (0.85% NaCl solution), and oscillate it thoroughly to mix it evenly, and dilute it to the required multiple. Take 1mL / 100μL of the gradient dilution solution and add it to the nutrient agar medium prepared in advance, and use a sterile coating rod to evenly spread the liquid on the surface of the medium. After the plate is coated and sealed, place it upside down in the incubator and culture it overnight at 37°C. The final colony count on the solid culture medium is 10-300 as the effective value. Each bacterial liquid sample is repeated 2 to 3 times, and the count average is taken.

[0105] 2.3 Evaluation of disinfection effect

[0106] Finally, according to the number of colonies on the plate, the concentration of Escherichia coli in the initial influent sample (N0, CFU / mL) and the concentration of surviving Escherichia coli in the effluent sample after treatment by the electrochemical device (N, CFU / mL) can be obtained.

[0107] 2.4 Data Analysis

[0108] The t-test is used for sample analysis, which takes into account the size and standard error of the sample, as well as the difference between the sample means. When performing a t-test, the t statistic is first calculated, and then the corresponding P value is determined based on the t distribution table or software tool, and then the P value is interpreted based on the significance level (usually 0.05). If the P value is less than the significance level, it is considered that there is a significant difference between the two sample means.

[0109] The experiment was conducted using the electrochemical disinfection device with a spiral flow channel in Example 1, and compared with the electrochemical disinfection device with a flat flow channel in the comparative example.

[0110] Test Example 1: Effect of Voltage on Disinfection Effect

[0111] Apply 2.8V to 3.4V voltage to carry out sterilization test of Escherichia coli self-prepared water sample. The treated solution contains ~10 7 CFU / mL E. coli in 100mM NaCl solution, flow rate set at 75mL / min. Take water samples before and after treatment for subsequent plate counts to determine concentration.

[0112] The voltage effect results are as follows Fig.10 As shown. Fig.10 It can be seen that as the voltage gradually increases, the two sets of disinfection devices have better and better sterilization effects on bacteria. When a voltage of 3.0V or above is applied, both sets of devices can completely inactivate bacteria at the same electrolyte concentration (100mM NaCl) and flow rate, showing the same sterilization ability.

[0113] However, under the voltage of 2.8V, the logarithmic removal rate of E. coli in the spiral flow channel structure disinfection device under the flow condition of 75mL / min reached 6.0log, achieving complete inactivation, and the logarithmic removal rate of E. coli in the flat flow channel device was 5.4log. By comparison, it can be seen that the disinfection device with a spiral structure has a better treatment effect than the flat flow channel under this condition, which is 0.6log higher. The results show that the spiral structure promotes the velocity distribution on the electrode surface of the device to a certain extent. The high speed near the electrode increases the mass transfer between the electrode and the solution, accelerates the electrolysis rate of the electrochemical disinfection device, and increases the contact probability between bacteria and active substances and the device, so that it shows a better sterilization effect under lower voltage (2.8V) conditions.

[0114] Under different voltage conditions, the flow rate was set to 50mL / min and the ion concentration of the treatment liquid was 10mM NaCl. The results are as follows: Fig.11 As shown in the figure, the inactivation ability of the two groups of disinfection devices on E. coli decreased with the decrease of the concentration of electrolytes in the treated water. At the voltages of 2.8V and 3.0V, the sterilization effect was not ideal. At 3.2V and 3.4V, the inactivation rates were 2.6log and 2.7log (spiral flow channel) and 2.4log and 2.5log (horizontal flow channel), respectively.

[0115] Compared with high ion concentration (100mM NaCl), the sterilization effect is significantly worse, and only a small number of bacteria can be killed. This phenomenon shows that the electrochemical disinfection device will electrolyze and produce more active oxidizing substances for sterilization under high ion concentration conditions, while lowering the ion concentration will weaken the indirect oxidation effect and the sterilization effect will become worse. This shows that the electrolyte ion concentration has a greater impact on the disinfection effect, and it can also explain that the indirect oxidation contribution of active oxidizing substances generated in the device accounts for the main part of the disinfection process.

[0116] Test Example 2: Disinfection Mechanism

[0117] The active chlorine in the water was neutralized by adding an excess of sodium thiosulfate solution, and the difference in disinfection effect between the two groups of devices with a flat flow channel and a spiral flow channel was compared. A 100mM NaCl electrolyte concentration bacterial solution was used, the flow rate was 50mL / min, and the voltage was used as the independent variable.

[0118] The results are as follows Fig.12In Test Example 1, under the condition of 100mM NaCl electrolyte concentration, the inactivation rate of E. coli by both devices can reach more than 5.6log or even completely inactivate. However, after adding sodium thiosulfate solution, the killing effect on bacteria decreased significantly, from complete inactivation (logarithmic removal rate>6log) to about 1log. In addition, by comparing the sterilization effects of the two groups of devices after adding sodium thiosulfate, it was found that the inactivation logarithm of the spiral structure flow channel device at different voltages was 0.45log, 0.87log and 1.1log (inactivation percentage 65%, 87% and 92%), which was higher than the 0.35log, 0.65log and 0.95log (inactivation percentage 55%, 77% and 89%) of the flat flow channel.

[0119] The disinfection mechanism of the electrochemical disinfection device used in this test example is a synergistic mechanism of direct oxidation and indirect oxidation. The active substances produced by indirect oxidation significantly improve the sterilization effect of the device.

[0120] The results showed that the inactivation rate of Escherichia coli in the spiral flow channel device was higher than that in the flat flow channel. This shows that the spiral flow channel reduces the dead zone near the electrode by enhancing the turbulence intensity and velocity distribution in the device, while also increasing the reaction contact time of the reactants in the cavity, allowing the bacteria to more fully contact the electrode, promoting the direct oxidation of the electrode, and increasing the contribution of direct oxidation of the electrode in the sterilization process.

[0121] Test Example 3: Effect of flow rate on disinfection effect

[0122] The same voltage (2.8V) was applied to disinfect the E. coli self-prepared water samples at flow rates of 50mL / min, 75mL / min, 100mL / min, and 125mL / min. The electrolyte concentration of the treated water samples was 100mM NaCl.

[0123] The inactivation effect of Escherichia coli in the two groups in 100mM NaCl electrolyte is shown in Figure 2. Fig.13 As shown. In general, there is no significant difference in the inactivation effect of the two groups of disinfection devices on E. coli, especially at flow rates of 50mL / min and 125mL / min. However, the same results as in the previous section show that the disinfection effect of the spiral flow channel device is slightly better than that of the flat flow channel at a flow rate of 75mL / min, and it is also found that the inactivation rate of E. coli in the spiral flow channel device is 0.6log higher than that of the flat flow channel at a flow rate of 100mL / min, which also reflects the sterilization advantage. With the increase of flow rate, the inactivation rate of bacteria in the two groups of disinfection devices gradually decreased. The inactivation rate of E. coli in the spiral flow channel decreased from 6.0log at 75mL / min to 5.7log at 100mL / min, and the flat flow channel also decreased from 5.4log to 5.1log.

[0124] In the experiment, the device with a spiral flow channel has a better disinfection effect, and the inactivation rate drops less when the flow rate changes than that of the flat flow channel. This is because the addition of the spiral structure makes the flow path of the fluid in the device longer. For the same reaction time, the rate of material reaction will increase, allowing the bacteria to be oxidized to a greater extent in the electrochemical device, achieving a better disinfection effect.

[0125] Test Example 4: Effect of different ion types on disinfection effect

[0126] This test case explores the effect of other salt ions on the disinfection efficiency of the electrochemical device. Na2SO4 is selected as a new electrolyte and added to the reaction for sterilization test. The configuration is equivalent to 100mM NaCl ion strength and the ion concentration is 34mMNa2SO4 solution. The fixed flow rate is 50mL / min, and the sterilization effect under different voltage conditions is investigated. The results are as follows Fig.14 .

[0127] From the previous results, it can be seen that under the same ionic strength conditions, when the electrolyte is NaCl and the water flow rate is the same, applying a voltage of 3.0V can achieve complete inactivation of E. coli, while Fig.14 Under the same treatment conditions, the logarithmic removal rates of Escherichia coli in solutions with electrolyte Na2SO4 were only 0.36log and 0.25log (inactivation percentages 56% and 44%), and the other two groups of voltage conditions were at a lower level; and the disinfection effects of the two groups of disinfection devices were very similar. The change in electrolyte caused the disinfection effects of the two groups of devices to decline significantly.

[0128] This is because almost no active oxidizing substances are produced during the electrolysis of sodium sulfate solution, and the disinfection effect becomes poor, which confirms that the indirect oxidation of the electrochemical disinfection device dominates the disinfection process, while the small number of bacteria killed is a manifestation of direct oxidation.

[0129] Test Example 5: Current Changes

[0130] The current changes were recorded at two electrolyte concentrations: 10 mM and 100 mM NaCl. The voltage change current was recorded as Fig.15 and Fig.16 As shown. The currents of both ion concentrations increase with the increase of voltage. Under the condition of 10mM NaCl, comparing the current changes of the two groups of devices, the current intensity of the flat channel is slightly higher than that of the spiral channel; under the condition of high ion concentration, the currents of the two groups of devices tend to be the same. Therefore, as the ion concentration increases, the difference in current intensity will gradually decrease. The low-concentration spiral structure does not show the advantage of promoting the electric field current but is lower than the flat channel. This is because after adding the spiral structure, part of the volume of the electrochemical reaction device is sacrificed, resulting in a reduction in the effective area of ​​the treated water contacting the electrode, and the current intensity is relatively low. The volume of the spiral channel is about 79.5cm3 , accounting for nearly 28% of the internal volume of the flow channel; the effective surface area of ​​the anode and cathode is 56.54cm 2 , the contact area of ​​spiral flow channel accessories is about 13.85cm 2 , occupying nearly 1 / 4 of the contact area. Under high concentration conditions, due to the high electrolyte concentration, the phenomenon that occurs at low ion concentration can be alleviated.

[0131] In terms of the sterilization effect under low ion concentration (10mM NaCl), the inactivation rates of E. coli in the two groups of disinfection devices were similar. When a voltage of more than 3.2V was applied, the disinfection effect of the spiral flow channel device was slightly better than that of the flat flow channel. In this case, although the current of the spiral flow channel disinfection device was lower, the sterilization effect was better than that of the flat flow channel, indicating that the spiral structure enhanced the turbulence intensity and velocity distribution inside the device, increased the contact efficiency between bacteria and electrolytes and electrodes, and thus improved the disinfection level.

[0132] Test Example 6: Storage growth and decline characteristics after disinfection

[0133] In this test example, the electrochemical disinfection device with spiral flow channel accessories was used at a voltage of 3.0V and different ionic strengths (10mM and 100mM NaCl). The treated water was stored at room temperature for 12 hours. Similarly, the raw water sample that was not disinfected was taken as the control group and stored for 12 hours under the same conditions. Sampling was carried out immediately after the water was discharged, 2 hours, 4 hours, 6 hours, and 12 hours, and the change in bacterial concentration of the disinfected water samples was determined by plate counting. The change in the concentration of E. coli during storage is shown in Figure 2. Fig.17 .

[0134] According to the previous results, the bactericidal effect is good under high salinity conditions, so Fig.17 Under medium salinity conditions of 100 mM NaCl, the bacteria were completely inactivated after disinfection by the device, and no bacteria revived and grew again during the 12 h storage period. Under low salinity conditions (10 mM NaCl), the bacterial concentration in the water sample immediately after disinfection was about 2 × 10 6 CFU / mL. During the 12h storage, the number of bacteria showed a downward trend. After 12h, the bacterial concentration was about 1×10 5 CFU / mL, Fig.18 About 80% of the bacteria lost their activity during storage. In contrast, during the storage of the raw water sample used as the control group, the concentration curve remained relatively flat, and the change in bacterial concentration was negligible.

[0135] From the above results, it can be seen that the bacteria disinfected by plug-flow electrochemical reaction did not revive and regrow, and even the number of bacteria decreased during storage in the water.

[0136] This shows that the damage to bacterial cells caused by the disinfection device in this study is irreversible. Under certain conditions, bacteria that are not completely inactivated will also show a decreasing trend in the number of water samples taken out during storage, indicating that some bacteria are also damaged during the disinfection process. However, if they are spread on nutrient agar solid culture medium, these bacteria can still survive and reproduce; the cell membrane of bacteria stored in the water body will be further damaged, and they will gradually die. Therefore, the disinfection device achieves the ability to continuously kill bacteria through the free chlorine it produces.

[0137] Test Example 7: Long-term operation characteristic test

[0138] The long-term operation characteristics of the spiral flow channel device were tested, including the inactivation performance of E. coli and the change of current during operation. The device was operated for 72 hours at a voltage of 3.0V, an ion concentration of 10mM NaCl, and a flow rate of 10mL / min. Water samples were taken and plate counted at 2h, 4h, 6h, 12h, 24h, 48h, 60h, and 72h. The disinfection effect was as follows: Fig.19 , under the set time and conditions, complete inactivation of Escherichia coli is achieved, and no live bacteria are detected on the plate coated with the effluent after 72 hours, which can maintain a high-efficiency disinfection effect.

[0139] This test example also monitors the current fluctuation of the disinfection device during long-term operation, such as Fig. 20 As shown in the figure, the current remains relatively stable and shows a gradual upward trend. This may be because some electrolytes remain on the electrode surface after long-term operation, causing the current to increase slowly. Therefore, the disinfection device is stable and sustainable, providing the possibility for long-term operation applications.

[0140] Test conclusion:

[0141] A numerical simulation comparison analysis was conducted on the disinfection device with a spiral flow channel structure and the flat flow channel disinfection device, and the distribution of flow velocity, turbulence intensity, etc. of the two disinfection devices was obtained. It was found that the addition of the spiral structure makes the fluid flow trajectory tend to flow in a spiral special structure; when the water inlet flow rate is 50m / min, the overall average speeds in the spiral flow channel and the flat flow channel device are 0.005m / s and 0.0005m / s respectively, and the speed of the spiral flow channel is increased to 10 times that of the flat flow channel; the turbulence intensity distribution is also more uniform, the turbulence intensity in the flow channel area of ​​the flat flow channel device is only 0.1%, and the inside of the spiral flow channel remains at 0.4%, which is 300% higher than that in the flat flow channel device; the speed close to the electrode in the spiral flow channel device reaches 0.01m / s, the turbulence on the electrode surface increases, the turbulence intensity is at 0.5%, and the turbulent kinetic energy increases from 0.000001m in the flat flow channel. 2 / s 3 Increased more than 10 times to 0.000016m 2 / s3 , the dead zone between the electrode and the flow channel components is reduced, and the mass transfer efficiency of the device is improved.

[0142] A comprehensive analysis was conducted on the results of the two groups of devices under different experimental conditions. When a voltage of 2.8V was applied and the electrolyte concentration of 100mM NaCl bacterial solution was treated at a flow rate of 75mL / min and 100mL / min, the spiral flow channel disinfection device had a 0.6log higher inactivation rate for Escherichia coli than the flat flow channel disinfection device, and the bactericidal effect was better than the flat flow channel. When the flow rate was set to 50mL / min and a voltage of 3.2V and 3.4V was applied to treat a low ion concentration (10mM NaCl) bacterial solution, the spiral flow channel device had a 0.1log higher inactivation rate for Escherichia coli than the flat flow channel, which also reflected a better bactericidal effect.

Claims

1. A spiral flow channel plug flow electrochemical disinfection device, characterized in that: The device comprises: a cathode and an anode arranged in a concentric tubular shape, a spiral flow channel is arranged between the cathode and the anode, a feed component and a discharge component are arranged at the bottom and top of the cathode and the anode respectively, the feed component is provided with a feed port, and the discharge component is provided with a discharge port.

2. The spiral flow channel plug flow electrochemical disinfection device according to claim 1, characterized in that: The spiral flow channel comprises a spiral structure and a supporting structure arranged on the spiral structure.

3. The spiral flow channel plug flow electrochemical disinfection device according to claim 1, characterized in that: The cathode and anode are both cylindrical structures; preferably, they are cylindrical structures made of metal.

4. The spiral flow channel plug flow electrochemical disinfection device according to claim 1, characterized in that: The anode is located on the outside, and the cathode is located on the inside.

5. The spiral flow channel plug flow electrochemical disinfection device according to claim 1, characterized in that: The distance between the cathode and the anode is the same as the width of the spiral structure.

6. Use of the spiral flow channel plug flow electrochemical disinfection device according to any one of claims 1 to 5, characterized in that: Used for electrochemical disinfection and sterilization; preferably used for electrochemical disinfection and sterilization in sewage treatment processes.

7. An electrochemical disinfection method, comprising using the spiral flow channel plug flow electrochemical disinfection device according to any one of claims 1 to 5, comprising the following steps: The cathode and anode of the spiral flow channel plug flow electrochemical disinfection device are connected to the power supply respectively, the liquid to be treated enters the spiral flow channel plug flow electrochemical disinfection device through the feed inlet, the liquid flows along the spiral flow channel, and the power supply is started to electrochemically disinfect the liquid.

8. The electrochemical disinfection method according to claim 7, characterized in that: The flow rate of the liquid to be treated at the feed inlet is ≤110mL / min.

9. The electrochemical disinfection method according to claim 7, characterized in that: The voltage between cathode and anode is 2.8-3.6V.

10. The electrochemical disinfection method according to claim 7, characterized in that: During the electrochemical disinfection process, electrolytes are also added to the liquid to be treated; Preferably, the type of electrolyte is hydrochloride; Preferably, the concentration of electrolyte added is controlled to be 10-100 mmol / L.

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