Method and system for activating percarbonic acid to inactivate bacteria in water body by using sunlight

Abstract

The invention discloses a method and system for activating percarbonate to inactivate bacteria in a water body by using sunlight, and belongs to the technical field of water body bacteria inactivation, the method for inactivating bacteria in the water body comprises the following steps: dissolving percarbonate in a to-be-treated bacteria-containing water body to form a mixed system; the obtained mixed system is subjected to a reaction under the sunlight illumination condition, and bacteria inactivation is achieved. The percarbonate is excited by sunlight for water sterilization and disinfection for the first time, rapid and efficient inactivation of bacteria in water can be achieved, the method can adapt to various different water conditions, the provided method is safe and stable, an excitant does not need to be introduced, the risk of releasing other excitant components is avoided, disinfection by-products are not generated in the disinfection process, and the method is environmentally friendly. Safety is realized; in addition, chemical reagents and equipment required by the method provided by the invention are easy to obtain, and the method is simple and convenient to operate, high in application value and easy to popularize.

Description

Technical Field

[0001] The present application relates to the technical field of water body bacteria inactivation, and in particular to a method and system for inactivating bacteria in water bodies by using sunlight to activate percarbonate. Background Art

[0002] With the development of science and technology, aquatic pathogenic microbial pollution has attracted more and more attention. Among them, bacterial contamination of water bodies is an increasingly common problem around the world, posing a huge threat to human health. Traditional water treatment sterilization and disinfection methods include chlorination disinfection, chlorine dioxide disinfection, ozone disinfection and ultraviolet disinfection. Among them, chlorination disinfection has the risk of incomplete microbial removal and disinfection by-products; chlorine dioxide disinfection has the problem of high cost and unstable toxicity; ozone disinfection and ultraviolet disinfection are not sustainable and have high production costs. Therefore, it is urgent to develop safe, efficient and stable water bacterial disinfection technology.

[0003] Advanced oxidation technology can produce active species such as hydroxyl radicals and superoxide radicals, which are used to inactivate bacteria in water. For example, a study achieved complete inactivation of two types of bacteria through ultraviolet light-catalyzed chlorine disinfection. Other researchers used ascorbic acid and pyrite to activate periodate to quickly inactivate bacteria in water. However, these technologies inevitably introduce low-concentration impurities in the environment such as disinfection by-products, iron ions, and iodates, which can easily cause secondary pollution.

[0004] Existing methods for inactivating bacteria in water bodies may release ions or other components on the catalyst by adding additional stimulants to the water, thereby causing secondary pollution. These methods will inevitably introduce secondary pollutants such as organic matter, iron ions, and sulfate ions. If some chlorine-containing disinfectants are used, carcinogenic, teratogenic, and mutagenic disinfection byproducts will be produced. In summary, these technologies will have the risk of secondary pollution after being put into large-scale practical application, which is a major defect of the existing technology. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the present invention provides a method and system for inactivating bacteria in water by homogeneously activating percarbonate using sunlight, so as to solve the problems in the prior art. The method for inactivating bacteria in water using this technology can reduce secondary pollution and save energy.

[0006] The present invention adopts the following technical solution.

[0007] The first aspect of the present invention discloses a method for inactivating bacteria in water by activating percarbonate with sunlight, comprising the following steps:

[0008] dissolving percarbonate in the bacteria-containing water to be treated to form a mixed system;

[0009] The obtained mixed system is placed under sunlight illumination to react and achieve bacterial inactivation.

[0010] Preferably, the mixed system is prepared by weighing a bacteria-containing water body with a set bacteria concentration, adding percarbonate thereto to reach the set concentration, and mixing evenly to obtain a mixed system.

[0011] Preferably, the percarbonate is one or both of sodium percarbonate or potassium percarbonate.

[0012] Preferably, the percarbonate concentration of the mixed system is 0.1 to 4 mmol / L.

[0013] Preferably, the bacteria-containing water body refers to water body containing Escherichia coli, Bacillus subtilis or Pseudomonas.

[0014] Preferably, the set bacterial concentration of the bacteria-containing water body is 1×10 7 Total colony count / mL.

[0015] Preferably, the sunlight illumination condition is any one of natural sunlight illumination or xenon lamp simulated sunlight illumination.

[0016] Preferably, the illumination intensity of the sunlight illumination condition is 25 to 100 mW / cm2, and the illumination time is 10 to 40 minutes.

[0017] Preferably, the temperature is controlled at 25°C during the reaction.

[0018] The second aspect of the present invention discloses a system for inactivating bacteria in water by using sunlight to activate percarbonate, and the method for inactivating bacteria in water by using sunlight to activate percarbonate comprises: a mixing module and a reaction module;

[0019] The mixing module includes a beaker and a circulating water system, which is used to dissolve percarbonate in the bacteria-containing water to be treated to obtain a mixed system;

[0020] The reaction module includes a xenon lamp, which is used to react the mixed system under sunlight conditions to achieve bacterial inactivation.

[0021] Compared with the prior art, the beneficial effects of the present invention include at least:

[0022] This application is the first to use sunlight to stimulate percarbonate for water disinfection and sterilization; this technology can achieve rapid and efficient inactivation of bacteria in water, inactivating 1×10 7Total colony count / ml of bacteria; this technology can completely inactivate bacteria in water, and dead bacteria can no longer be reborn through culture; this technology can adapt to a variety of different water conditions, including: different concentrations of common anions and cations, different concentrations of natural organic matter, different pH values, etc. This technology performs well in water bodies from various sources, such as: tap water, river water, lake water, sea water, secondary sedimentation tank effluent and other actual water bodies; the method provided by the present application is safe and stable, does not require the introduction of an stimulant, and has no risk of release of other stimulant components. No disinfection by-products are produced during the disinfection process, and residual hydrogen peroxide will be consumed by bacterial residues, and ultimately only carbonate / bicarbonate will be introduced, which is green and safe; in addition, the chemical reagents and equipment required for the method provided by the present application are easy to obtain, simple to operate, high in application value, and easy to promote. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 is the disinfection performance of different reaction systems on E. coli in water;

[0024] Figure 2 is the disinfection performance of the percarbonate / simulated sunlight system against different bacteria in water;

[0025] Figure 3 It is the detection of hydroxyl radicals and superoxide radicals in the process of simulating the sunlight activation of percarbonate reaction;

[0026] Figure 4 It simulates the bacterial disinfection performance of the sunlight / percarbonate system in different water bodies;

[0027] Figure 5 It is the disinfection performance of the percarbonate / simulated sunlight system coupled with a continuous flow device against bacteria;

[0028] Figure 6 It is the disinfection performance of the natural sunlight / percarbonate reaction system in a tank containing actual water;

[0029] Figure 7 It is the disinfection performance of the natural sunlight / percarbonate reaction system in plastic bottles containing actual water. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present invention clearer, the technical scheme of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The embodiments described in this application are only embodiments of a part of the present invention, rather than all embodiments. Based on the spirit of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention.

[0031] At present, photoactivation technology is considered to be one of the most promising technologies for inactivating bacteria in water due to its advantages in reducing secondary pollution and saving energy. Among them, solar radiation (wavelength is mostly greater than 300nm) as a renewable energy source can be used to excite percarbonate for inactivating bacteria in water, but no relevant research has been reported.

[0032] Solid percarbonate (PC) is finally converted into bicarbonate, water and oxygen after the reaction. The product is green and safe. After activation, it can produce active species such as hydroxyl radicals and carbonate radicals for use in water treatment. Photoactivation is a cleaner technology compared to chemical catalysis. It has attracted much attention in the field of pollution control, especially in the field of water treatment. Studies have found that PC is activated by ultraviolet light. 254 After excitation, highly active carbonate radicals will be generated in water, which can degrade common organic pollutants, but UV activation requires the use of UV lamps, which consumes a lot of energy. Considering that solar radiation (wavelength greater than 300nm) is a renewable energy source, it is expected to stimulate PC to produce active species, but no research has been reported so far.

[0033] The inventors have found through research that percarbonate in water will decompose into common substances present in natural water bodies such as water and carbonate after being stimulated by sunlight and sterilized. These substances are completely non-toxic and harmless, and do not cause the generation of other harmful by-products. Under this premise, this technology is also relatively excellent in the inactivation of bacteria in water bodies. Therefore, this technology not only avoids the generation of disinfection by-products, but also can efficiently inactivate bacteria in water bodies.

[0034] The purpose of this technology is to provide a method for inactivating bacteria in water by homogeneously activating percarbonate using sunlight, so as to solve the problems existing in the prior art. The method for inactivating bacteria in water using this technology can reduce secondary pollution and save energy.

[0035] The invention discloses a method for inactivating bacteria in water by activating percarbonate using sunlight, comprising the following steps:

[0036] Step 1, dissolving percarbonate in the bacteria-containing water to be treated to form a mixed system;

[0037] In a preferred but non-limiting embodiment of the present invention, step 1 specifically includes weighing bacteria-containing water with a set bacteria concentration, adding percarbonate thereto to reach the set concentration, and mixing evenly to obtain a mixed system.

[0038] Preferably, the percarbonate is one or both of sodium percarbonate or potassium percarbonate.

[0039] Preferably, the percarbonate concentration of the mixed system is set to 0.1-4 mmol / L.

[0040] Preferably, the bacteria-containing water body refers to water body containing Escherichia coli, Bacillus subtilis or Pseudomonas.

[0041] Preferably, the set bacterial concentration of the bacteria-containing water body is 1×10 7 Total colony count / mL.

[0042] Step 2, placing the mixed system obtained in step 1 under sunlight conditions for reaction to achieve bacterial inactivation.

[0043] In a preferred but non-limiting embodiment of the present invention, the sunlight illumination condition in step 2 is any one of natural sunlight illumination or xenon lamp simulated sunlight illumination.

[0044] Further preferably, the illumination intensity of the sunlight illumination condition is 25 to 100 mW / cm2.

[0045] Preferably, the illumination time of the sunlight illumination condition is 10 to 40 minutes.

[0046] Preferably, the temperature is controlled at 25°C during the reaction.

[0047] Example 1

[0048] Disinfection of Escherichia coli in water by different reaction systems

[0049] In a 100 mL double-layer beaker, add 50 mL of E. coli S-17 dispersion (initial bacterial concentration is 1×10 7 percarbonate was added to the water containing E. coli to a concentration of 1 mmol / L, and the mixture was thoroughly mixed under magnetic stirring to obtain a composite system. The composite system was irradiated with simulated sunlight, wherein the light intensity was set to 50 mW / cm 2 ), and the temperature was maintained at 25°C by a circulating water system. Under the same conditions, five reaction systems were selected as control systems, including: only irradiated with simulated sunlight, adding percarbonate and placed in a dark environment, adding carbonate and irradiated with simulated sunlight, adding hydrogen peroxide and irradiated with simulated sunlight, and adding percarbonate and irradiated with simulated sunlight. Samples were taken at regular intervals during the reaction, inoculated onto solid culture media by the dilution coating plate method, and placed in a constant temperature incubator and cultured at 37°C for 24 hours. The data were obtained to draw a bactericidal kinetic curve. The results are shown in the figure. Figure 1 As shown, sodium percarbonate has the best disinfection effect on Escherichia coli under a system of simulated sunlight.

[0050] Example 2

[0051] Disinfection of different bacteria in water by percarbonate / simulated sunlight system

[0052] Example 1 was repeated with the following differences: the E. coli dispersion was replaced with Bacillus subtilis, E. coli MG1655, and Pseudomonas dispersions. During the reaction, the reaction time of sampling was 0, 5, 10, 20, 30, 40, and 60 minutes. The results are as follows: Figure 2 As shown, under the percarbonate / simulated sunlight system, different bacteria in the water body are disinfected effectively.

[0053] Example 3

[0054] Detection of free radicals in the process of percarbonate activation by simulated sunlight

[0055] Take 99 μL of sodium percarbonate aqueous solution (20 mM) and hydrogen peroxide (H2O2) aqueous solution (30 mM), add 1 μL of 5,5-dimethyl-1-pyrrolidine-N-oxide (DMPO) to form a mixed solution, which is used as the test solution for hydroxyl radicals and carbonate radicals. Add 5 μL of sodium percarbonate aqueous solution to 94 μL of dimethyl sulfoxide (DMSO) to make the final concentration 5 mM, and add 1 μL of DMPO to form a mixed solution, which is used as the test solution for superoxide radicals. Use capillaries to absorb the above test solutions respectively, place them in an electron spin resonance spectrometer (ESR; Bruker EMX / Plus, Germany), and detect them under simulated sunlight. The generation of the corresponding free radicals can be inferred from the characteristic peak type, and the results are as follows. Figure 3 shown.

[0056] Example 4

[0057] Disinfection of bacteria in different water bodies by simulated sunlight / percarbonate system

[0058] In a 100 mL double-layer beaker, add 50 mL of tap water, river water, and water from the secondary sedimentation tank, respectively, and add Escherichia coli S-17 stock solution to make its initial viable bacterial concentration 1×10 7 CFU / mL. Percarbonate was added to the above-mentioned water containing E. coli to a concentration of 1 mmol / L, and the composite system was fully mixed under magnetic stirring. The composite system was irradiated with simulated sunlight, wherein the light intensity was set to 50 mW / cm 2 The temperature was maintained at 25°C by a circulating water system. Samples were taken regularly during the reaction, inoculated onto solid culture medium by dilution and spreading plate method, and placed in a constant temperature incubator for 24 hours at 37°C. The data were obtained to draw a bactericidal kinetic curve. The results are shown in Figure 4 It can be seen that the sunlight / percarbonate system is effective in disinfecting bacteria in different water bodies.

[0059] Example 5

[0060] Percarbonate / simulated sunlight system coupled with continuous flow device for bacterial disinfection

[0061] The reaction was carried out in a continuous flow device. The solution containing E. coli S-17 was mixed with the percarbonate solution and then passed into the reaction device. The reaction device was irradiated with simulated sunlight, wherein the light intensity was set to 50 mW / cm 2 During the reaction, samples were taken from the effluent at regular intervals, inoculated onto solid culture medium by dilution and coating plate method, and placed in a constant temperature incubator for 24 hours at 37°C. The data were obtained to draw the sterilization kinetic curve of the effluent live bacteria concentration. The results are shown in the figure. Figure 5 .

[0062] Example 6

[0063] Disinfection of bacteria by natural sunlight / percarbonate reaction system in a tank containing real water

[0064] A 1L rectangular water tank was used as the reaction vessel. Different water bodies were added, including 0.9% sodium chloride brine, tap water, river water, and secondary sedimentation tank effluent. Escherichia coli S-17 stock solution was added to make its initial viable bacterial concentration 1×10 7 CFU / mL. Add percarbonate to the above water containing E. coli to make its concentration 1mmol / L. Place the reaction device under natural sunlight, take samples from the effluent at regular intervals during the reaction, inoculate them onto solid culture medium by dilution coating plate method, and place them in a constant temperature incubator and culture them at 37℃ for 24 hours. The data obtained are used to draw the bactericidal kinetic curve of the effluent live bacteria concentration. The results are as follows Figure 6 .

[0065] Example 7

[0066] Disinfection of bacteria in plastic bottles containing real water using a natural sunlight / percarbonate reaction system

[0067] A 5L plastic bottle was used as a reaction container. Different water bodies were added, including 0.9% sodium chloride brine, tap water, river water, and secondary sedimentation tank effluent. Escherichia coli S-17 stock solution was added to make its initial viable bacterial concentration 1×10 7 CFU / mL. Add percarbonate to the above water containing E. coli to make its concentration 1mmol / L. Place the reaction device under natural sunlight, take samples from the effluent at regular intervals during the reaction, inoculate them onto solid culture medium by dilution coating plate method, and place them in a constant temperature incubator and culture them at 37℃ for 24 hours. The data obtained are used to draw the bactericidal kinetic curve of the effluent live bacteria concentration. The results are as follows Figure 7 .

[0068] The present invention also discloses a system for inactivating bacteria in water by activating percarbonate using sunlight, comprising: a mixing module and a reaction module;

[0069] A mixing module, including a beaker and a circulating water system, is used to dissolve percarbonate in the bacteria-containing water to be treated to obtain a mixed system;

[0070] The reaction module includes a xenon lamp, which is used to react the mixed system under sunlight conditions to achieve bacterial inactivation.

[0071] Compared with the prior art, the beneficial effects of the present invention include at least:

[0072] This application is the first to use sunlight to stimulate percarbonate for water disinfection and sterilization; this technology can achieve rapid and efficient inactivation of bacteria in water, inactivating 1×10 7 Total colony count / ml of bacteria; this technology can completely inactivate bacteria in water, and dead bacteria cannot be revived by culture; this technology can adapt to a variety of different water conditions, including: different concentrations of common anions and cations, different concentrations of natural organic matter, different pH values, etc. This technology performs well in water bodies from various sources, such as: tap water, river water, lake water, sea water, secondary sedimentation tank effluent and other actual water bodies; the method provided by the present application is safe and stable, does not require the introduction of an stimulant, and has no risk of release of other stimulant components. No disinfection by-products are produced during the disinfection process, and residual hydrogen peroxide will be consumed by bacterial residues, and ultimately only carbonate / bicarbonate will be introduced, which is green and safe; in addition, the chemical reagents and equipment required for the method provided by the present application are easy to obtain, simple to operate, high in application value, and easy to promote.

[0073] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the relevant field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents, and any modifications or equivalent replacements that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for inactivating bacteria in water by activating percarbonate using sunlight, characterized in that: The following steps are involved: dissolving percarbonate in the bacteria-containing water to be treated to form a mixed system; The obtained mixed system is placed under sunlight illumination to react and achieve bacterial inactivation.

2. A method for inactivating bacteria in water by using sunlight to activate percarbonate according to claim 1, characterized in that: The mixed system is prepared by weighing a bacteria-containing water body with a set bacteria concentration, adding percarbonate thereto to reach the set concentration, and mixing evenly to obtain the mixed system.

3. A method for inactivating bacteria in water by using sunlight to activate percarbonate according to claim 2, characterized in that: The percarbonate is one or both of sodium percarbonate and potassium percarbonate.

4. A method for inactivating bacteria in water by using sunlight to activate percarbonate according to claim 2, characterized in that: The percarbonate concentration of the mixed system is 0.1-4 mmol / L.

5. A method for inactivating bacteria in water by using sunlight to activate percarbonate according to claim 2, characterized in that: The bacteria-containing water body refers to a water body containing Escherichia coli, Bacillus subtilis or Pseudomonas.

6. A method for inactivating bacteria in water by using sunlight to activate percarbonate according to claim 2, characterized in that: The set bacterial concentration of the bacteria-containing water body is 1×10 7 Total colony count / mL.

7. A method for inactivating bacteria in water by activating percarbonate with sunlight according to claim 1, characterized in that: The sunlight illumination condition is any one of natural sunlight illumination or xenon lamp simulated sunlight illumination.

8. A method for inactivating bacteria in water by activating percarbonate with sunlight according to claim 1, characterized in that: The illumination intensity of the sunlight illumination condition is 25 to 100 mW / cm2, and the illumination time is 10 to 40 minutes.

9. A method for inactivating bacteria in water by activating percarbonate with sunlight according to claim 1, characterized in that: The temperature was controlled at 25°C during the reaction.

10. A system for inactivating bacteria in water by using sunlight to activate percarbonate, which implements the method for inactivating bacteria in water by using sunlight to activate percarbonate according to any one of claims 1 to 9, characterized in that: include: Mixing module and reaction module; The mixing module includes a beaker and a circulating water system, which is used to dissolve percarbonate in the bacteria-containing water to be treated to obtain a mixed system; The reaction module includes a xenon lamp, which is used to react the mixed system under sunlight conditions to achieve bacterial inactivation.

Images