Method for disinfecting drinking water by combining solid hydrogen peroxide with ultrasonic waves and ultraviolet rays

Abstract

The invention belongs to the technical field of drinking water disinfection, and particularly relates to a method for disinfecting drinking water by combining solid hydrogen peroxide with ultrasonic waves and ultraviolet rays, which is specifically divided into two sections of disinfection: the first section of disinfection is coating solid hydrogen peroxide and ultrasonic wave combined disinfection; the water subjected to the first-stage disinfection enters the second-stage disinfection, and the second-stage disinfection is to irradiate ultraviolet rays into the water so as to complete the disinfection of the drinking water. Sodium citrate and quaternary ammonium salt are used for coating solid hydrogen peroxide, so that the solid hydrogen peroxide is good in stability, non-toxic, suitable for disinfecting drinking water and free of influence on the quality of the drinking water, and the coating process is simple; the prepared coating solid hydrogen peroxide, ultrasonic waves and ultraviolet rays are combined to disinfect drinking water, a synergistic effect is achieved, the disinfection effect of the coating solid hydrogen peroxide is improved through the ultrasonic waves and the ultraviolet rays, the whole disinfection time is short, and the sterilization rate is high; the disinfection method is simple, low in cost, easy to operate, suitable for large-scale popularization and use and wide in market prospect.

Description

Technical field:

[0001] The invention belongs to the technical field of drinking water disinfection, and in particular relates to a method for disinfecting drinking water by combining solid hydrogen peroxide with ultrasound and ultraviolet rays. Background technology:

[0002] Hydrogen peroxide is a strong oxidant. A certain concentration of hydrogen peroxide solution can kill microorganisms including bacterial propagules, spores, fungi and viruses without any residue or toxicity. It is often used for disinfection in water plants. However, hydrogen peroxide is a hazardous chemical and is inconvenient to transport and use.

[0003] Solid hydrogen peroxide, also known as sodium percarbonate, is a strong oxidant with a chemical formula of 2Na2CO3·3H2O2. It is a white crystalline powder that can release oxygen when exposed to moisture. Sodium percarbonate is an addition compound of hydrogen peroxide and sodium carbonate. It is mainly used as a bleaching agent and oxidant, as well as a detergent, cleaning agent, and disinfectant in the chemical, papermaking, textile, dyeing and finishing, food, medicine, and health sectors. Since solid hydrogen peroxide is unstable, a stabilizer is added during production, and a coating agent is added to the external stabilizer. In the past, borates, perborates, phosphoric acid or phosphates were used for coating, and the coating effect was good. It was mainly used in washing, sewage treatment and other fields. However, drinking water disinfection has more stringent requirements on the coating components of the disinfectant. At present, no coated solid hydrogen peroxide with good disinfection effect and simple process for drinking water disinfection has been found, and there are few studies on the method of using coated solid hydrogen peroxide to disinfect drinking water. Further research and improvement are needed to make the drinking water disinfection method simple, low-cost and effective. Summary of the invention:

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for disinfecting drinking water by using solid hydrogen peroxide in combination with ultrasound and ultraviolet rays. The solid hydrogen peroxide coated with sodium citrate is combined with ultrasound and ultraviolet rays to disinfect drinking water, and the disinfection effect is good and the amount of chemical reagents used is small.

[0005] In order to achieve the above object, the present invention provides a method for disinfecting drinking water with solid hydrogen peroxide combined with ultrasound and ultraviolet light, and the specific steps are as follows:

[0006] (1) Preparation of coated solid hydrogen peroxide: The coating material is a mixture of sodium citrate and quaternary ammonium salt cationic surfactant, according to the mass percentage: sodium citrate 55-75%, quaternary ammonium salt cationic surfactant 25-45%; anhydrous magnesium sulfate is selected as a desiccant and stabilizer; quaternary ammonium salt is selected as a surfactant. Quaternary ammonium salt cationic surfactant can improve wet stability and thermal stability, has a lower critical micelle concentration when dissolved, and has good emulsification performance, foaming and foam stabilization ability, and has good water solubility and salt resistance. It can more effectively reduce surface tension and has a significant synergistic effect on the bactericidal effect of solid hydrogen peroxide. The specific preparation method is:

[0007] 1) mixing sodium citrate and a quaternary ammonium salt cationic surfactant uniformly to prepare a mixed solvent, which is a coating material;

[0008] 2) preheating the fluidized bed to 40-45° C., spraying the prepared coating material onto the surface of the solid hydrogen peroxide in the fluidized bed to obtain solid hydrogen peroxide with a primary coating;

[0009] 3) Continue to spray the coating material on the solid hydrogen peroxide that has been coated once in the fluidized bed, and the coating material sprayed twice accounts for 0.1-5% of the mass of the solid hydrogen peroxide; the particle size of the solid hydrogen peroxide particles after the two coatings is 1-3 mm;

[0010] 4) The solid hydrogen peroxide after the double coating is sent to a fluidized bed dryer through a conveying system for drying, the drying temperature is controlled at 70-80° C., and the feeding and discharging speed of the dryer is controlled to ensure the material layer thickness and good fluidization state of the dryer. After drying, it is mixed with anhydrous magnesium sulfate to obtain a coated solid hydrogen peroxide product, which is then packaged, inspected, and stored in accordance with production requirements; the amount of anhydrous magnesium sulfate added is 1%-2% of the mass of the coated solid hydrogen peroxide;

[0011] (2) Disinfection: The water is disinfected using coated solid hydrogen peroxide combined with ultrasound and ultraviolet light. The disinfection is specifically divided into two stages. The first stage of disinfection is the combined disinfection of coated solid hydrogen peroxide and ultrasound. The mass volume ratio of the input amount of coated solid hydrogen peroxide to water is 3-6 mg:1L. The ultrasonic frequency is 59kHz and the power is 90W. The water that has completed the first stage of disinfection enters the second stage of disinfection. The second stage of disinfection is to irradiate the water with ultraviolet light. The total duration of the two-stage disinfection of the water is 5-10 minutes to complete the disinfection of the drinking water.

[0012] The specific process of the first stage of disinfection of the present invention is as follows: an ultrasonic generator is arranged in the first stage disinfection tank, water enters the disinfection tank from the water inlet, and the coated solid hydrogen peroxide prepared in step (1) is added through the top opening of the disinfection tank, and the first stage disinfection takes 4-8 minutes.

[0013] The specific process of the second stage of disinfection of the present invention is as follows: an ultraviolet generator is arranged in the second stage disinfection pool, and the irradiation intensity is 70 μw / cm 2 The second disinfection time is 1-2 minutes.

[0014] Compared with the prior art, the invention uses sodium citrate and quaternary ammonium salt to coat solid hydrogen peroxide, so that the solid hydrogen peroxide has good stability and is non-toxic, is suitable for disinfecting drinking water, has no effect on the quality of drinking water, and has a simple coating process; the prepared coated solid hydrogen peroxide is combined with ultrasound and ultraviolet rays to disinfect drinking water, and has a synergistic effect; the ultrasound and ultraviolet rays improve the disinfection effect of the coated solid hydrogen peroxide, the entire disinfection time is short, and the sterilization rate is high; the disinfection method is simple, low in cost, easy to operate, suitable for large-scale promotion and use, and has broad market prospects. Description of the drawings:

[0015] Figure 1 It is a schematic diagram of the principle of the disinfection method involved in the present invention. Specific implementation method:

[0016] The present invention will be further described in detail below through specific embodiments in conjunction with the accompanying drawings.

[0017] Embodiment 1:

[0018] This embodiment relates to a method for disinfecting drinking water with solid hydrogen peroxide combined with ultrasound and ultraviolet light, and the specific steps are as follows:

[0019] (1) Preparation of coated solid hydrogen peroxide: The coating material is a mixture of sodium citrate and a quaternary ammonium salt cationic surfactant, wherein the mass percentage is: 55-75% sodium citrate and 25-45% quaternary ammonium salt cationic surfactant; sodium citrate is used as the coating material; anhydrous magnesium sulfate is selected as a desiccant and stabilizer; and a quaternary ammonium salt is selected as a surfactant. The quaternary ammonium salt cationic surfactant can improve wet stability and thermal stability, has a lower critical micelle concentration when dissolved, and has good emulsifying properties, foaming and foam stabilizing abilities, and has good water solubility and salt tolerance, can more effectively reduce surface tension, and has a significant synergistic effect on the bactericidal effect of solid hydrogen peroxide; the specific preparation method is as follows:

[0020] 1) mixing sodium citrate and a quaternary ammonium salt cationic surfactant uniformly to prepare a mixed solvent, which is a coating material;

[0021] 2) preheating the fluidized bed to 40-45° C., spraying the prepared coating material onto the surface of the solid hydrogen peroxide in the fluidized bed to obtain solid hydrogen peroxide with a primary coating;

[0022] 3) Continue to spray the coating material on the solid hydrogen peroxide that has been coated once in the fluidized bed, and the coating material sprayed twice accounts for 0.1-5% of the mass of the solid hydrogen peroxide; the particle size of the solid hydrogen peroxide particles after the two coatings is 1-3 mm;

[0023] 4) The solid hydrogen peroxide after the double coating is sent to a fluidized bed dryer through a conveying system for drying, the drying temperature is controlled at 70-80° C., and the feeding and discharging speed of the dryer is controlled to ensure the material layer thickness and good fluidization state of the dryer. After drying, it is mixed with anhydrous magnesium sulfate to obtain a coated solid hydrogen peroxide product, which is then packaged, inspected, and stored in accordance with production requirements; the amount of anhydrous magnesium sulfate added is 1%-2% of the mass of the coated solid hydrogen peroxide;

[0024] (2) First stage disinfection: The water is disinfected by using coated solid hydrogen peroxide combined with ultrasound. Specifically, an ultrasonic generator is set in the first stage disinfection tank. Water enters the disinfection tank from the water inlet. Coated solid hydrogen peroxide is added to the water. The mass volume ratio of solid hydrogen peroxide to water is 3 mg: 1 L. The ultrasonic frequency applied is 59 kHz and the ultrasonic power is 90 W. The water stays in the first stage disinfection tank for 4 minutes and then enters the second stage disinfection tank.

[0025] (3) Second stage disinfection: UV light is used to disinfect the water containing coated solid hydrogen peroxide. Specifically, a UV reactor (ultraviolet light reactor) is set in the second stage disinfection pool, the UVT (ultraviolet light transmittance / penetration) of the incoming water is greater than 90%, the total power of the UV reactor is 90 kW, and the ultraviolet dose is 200-800 mJ / cm 2 , the water residence time is 1 minute, completing the disinfection of drinking water.

[0026] The total duration of the two-stage disinfection in this embodiment is 5 minutes. The disinfection method of this embodiment can be used to disinfect a flow rate of 40,000 m 3 / d of water for disinfection.

[0027] This example tests drinking water before and after disinfection and finds that this disinfection process has a good control effect on macromolecular components represented by microbial degradation products and proteins, and has a good removal effect on DOC (soluble organic carbon), total organic matter uv254, 2-MIB (2-methylisoborneol) and THMs (trihalomethanes), HAAs and other disinfection byproduct precursors. The results are shown in Table 1.

[0028] Table 1 Test results of drinking water before and after disinfection

[0029] project DOC / (mg.L-') <![CDATA[UV254 / cm -1 ]]> 2-MIB / (ng.L') THMs precursor / (μg.L') HAAs precursor / (μg.L') Before disinfection 2.6～2.8 0.053～0.056 14～22 47.1～68.5 58.7～70.2 After disinfection 1.5～1.9 0.018～0.027 <5～10 22.7～41.2 31.5～37.4

[0030] Embodiment 2:

[0031] This embodiment relates to a method for disinfecting drinking water using sodium percarbonate combined with ultrasound and ultraviolet rays. The difference from Example 1 is that the mass volume ratio of the amount of coated solid hydrogen peroxide added to water is 6 mg:1 L, and the total disinfection time is 5 minutes.

[0032] Embodiment 3:

[0033] In order to verify the sterilization effect of the disinfection method of Example 1 and Example 2, this embodiment sets up 5 comparative examples, which are different from Example 1 in that: Comparative Example 1: only ultraviolet rays are used to disinfect drinking water; Comparative Example 2: only coated solid hydrogen peroxide is used to disinfect drinking water; Comparative Example 3: only ultrasound is used to disinfect drinking water; Comparative Example 4: coated solid hydrogen peroxide and ultraviolet rays are used for combined disinfection; Comparative Example 5: drinking water is disinfected using coated solid hydrogen peroxide and ultrasound; the contents of Escherichia coli and Staphylococcus aureus in the water before and after disinfection in Examples 1-2 and Comparative Examples 1-5 are detected, and the sterilization rate is calculated. The results are shown in Table 2.

[0034] Table 2 Bactericidal effect test results

[0035]

[0036] As can be seen from Table 2, both ultrasound and ultraviolet light have a synergistic effect on the sterilization of coated solid hydrogen peroxide, and the combined use of the three has the best disinfection effect. Ultraviolet irradiation can promote the decomposition of coated solid hydrogen peroxide to produce free radicals, which act on bacterial proteins and cortex, causing the microorganisms to die quickly.

[0037] Embodiment 4:

[0038] This example relates to the stability test of the coated solid hydrogen peroxide prepared in Example 1. The active oxygen content, moisture content, pH value, thermal stability, wet stability and total phosphorus content were tested by conventional testing methods in the art, with uncoated solid hydrogen peroxide as a comparison. The test results are shown in Table 3.

[0039] Table 3 Comparison of test results

[0040]

[0041]

[0042] From the comparison of the experimental results in Table 3, it can be clearly seen that the stability of coated solid hydrogen peroxide is much higher than that of uncoated solid hydrogen peroxide, and it will not affect its content and other properties. This is because the coating material composed of sodium citrate and quaternary ammonium salt cationic surfactant can form a coating on the surface of solid hydrogen peroxide particles. The formation of the coating material improves the thermal stability and wet stability of solid hydrogen peroxide; while uncoated sodium percarbonate has a strong hygroscopic effect, and its stability is greatly reduced after absorbing water. The hydrophilic and lipophilic properties of the surfactant are used to modify the surface of the solid hydrogen peroxide particles, reduce its water absorption, and improve the stability of sodium percarbonate.

Claims

1. A method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light, characterized in that: The disinfection is specifically divided into two stages. The first stage is the combined disinfection of coated solid hydrogen peroxide and ultrasound. The water that has completed the first stage of disinfection enters the second stage of disinfection. The second stage of disinfection is to irradiate ultraviolet rays into the water to complete the disinfection of drinking water.

2. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that: The mass volume ratio of the input amount of coated solid hydrogen peroxide to water is 3-6 mg:1L.

3. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that: The ultrasonic frequency is 59kHz and the power is 90W.

4. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that: The UV irradiation intensity is 70μw / cm 2 .

5. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that: The total time for the two-stage disinfection of water is 5-10 minutes; the first disinfection time is 4-8 minutes, and the second disinfection time is 1-2 minutes.

6. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that: The coated solid hydrogen peroxide is prepared by coating the solid hydrogen peroxide with sodium citrate and quaternary ammonium salt.

7. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 1, characterized in that: The preparation method of the coated solid hydrogen peroxide is: 1) mixing sodium citrate and a quaternary ammonium salt cationic surfactant uniformly to prepare a mixed solvent, which is a coating material; 2) preheating the fluidized bed to 40-45° C., spraying the prepared coating material onto the surface of the solid hydrogen peroxide in the fluidized bed to obtain solid hydrogen peroxide with a primary coating; 3) Continue to spray the coating material onto the solid hydrogen peroxide that has been coated once in the fluidized bed; 4) The solid hydrogen peroxide after the double coating is sent to a fluidized bed dryer through a conveying system for drying, the drying temperature is controlled at 70-80° C., and the feeding and discharging speed of the dryer is controlled to ensure the material layer thickness and good fluidization state of the dryer. After drying, it is mixed with anhydrous magnesium sulfate to obtain coated solid hydrogen peroxide.

8. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 7, characterized in that: The coating material sprayed twice accounts for 0.1-5% of the mass of solid hydrogen peroxide.

9. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet light according to claim 8, characterized in that: The added amount of anhydrous magnesium sulfate is 1%-2% of the mass of the coated solid hydrogen peroxide.

10. The method for disinfecting drinking water using solid hydrogen peroxide combined with ultrasound and ultraviolet rays according to claim 9, characterized in that: The mass percentages of sodium citrate and quaternary ammonium salt cationic surfactant are 55-75%: 25-45%.

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