Dual-molecular ultraviolet synergistic algae-removal method and application thereof

Abstract

The application provides a dual-molecular ultraviolet synergistic algae removal method and application thereof. The algae removal method comprises the following steps: adding an algae-containing water body to be treated into an ultraviolet reaction device, and irradiating by using a first ultraviolet light source and a second ultraviolet light source; wherein the main emission peak wavelength of the first ultraviolet light source is 222 nm; the main emission peak wavelength of the second ultraviolet light source is 308 nm; and the algae-containing water body contains cyanobacteria. The algae removal method can be applied to water treatment, can realize rapid inactivation of algae cells, can significantly reduce the revival rate of algae cells, and can improve the durability of the algae removal effect and the stability of long-term algae control. The algae removal method provided by the application does not need to add any chemical agent, has the advantages of green environmental protection, simple operation, easy integration with existing water treatment processes, and the like, and has wide application prospect.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology, specifically relating to a method for algae removal in water using ultraviolet radiation, and more particularly to a dual-excimer ultraviolet synergistic algae removal method and its application. Background Technology

[0002] With the increasing severity of eutrophication in water bodies, frequent cyanobacterial blooms have become a significant threat to the ecological environment quality of water sources and the safety of drinking water supply. Cyanobacterial blooms not only damage the structure and function of aquatic ecosystems and disrupt the stable operation of water intake, distribution, and conventional water purification processes, but also release algal toxins, odor substances, algal organic matter, and disinfection byproduct precursors during their growth, metabolism, decay, lysis, and treatment. This further increases the difficulty of drinking water treatment and exacerbates the risks to water supply safety.

[0003] Currently, the main treatment technologies for algae-containing water bodies and cyanobacterial blooms include physical methods, chemical algae removal methods, pre-oxidation methods, coagulation and sedimentation methods, and ultraviolet irradiation methods. However, existing algae removal technologies still have limitations in practical applications. Physical methods (such as mechanical dredging and physical barriers) can directly remove algae that have already accumulated in the water, but they are costly to operate and usually only address surface blooms, failing to curb the continued proliferation and recurrence of algae at the source. Ultrasonic and pressure methods mainly work by destroying the air sac structure of algal cells and weakening their buoyancy, causing them to settle naturally. Although these methods can increase the proportion of algal cells settling under certain conditions, they do not effectively inactivate algal cells. Settled algal cells still have the ability to regain buoyancy and regrow, thus limiting their effectiveness in long-term algae control and preventing recurrence. Chemical algicides and oxidants can quickly inactivate or inhibit the growth of algae in a short time, but under high algae density conditions, it is often necessary to increase the dosage to ensure treatment effectiveness. Insufficient dosage can cause algal cells to experience stress, potentially inducing the synthesis or release of algal toxins. Excessive dosage, on the other hand, can lead to massive cell lysis, triggering the concentrated release of intracellular algal toxins and algal organic matter, thus increasing the processing load on subsequent water purification processes and posing a potential threat to drinking water safety. The removal efficiency of conventional coagulation and sedimentation processes for algal cells is also limited by the characteristics of cyanobacteria themselves. Cyanobacterial cells contain gas sacs with strong buoyancy, making it difficult for them to sink effectively during coagulation and sedimentation, thus affecting solid-liquid separation and overall algae removal efficiency. Furthermore, traditional ultraviolet (UV) treatment technologies (such as 254 nm UV radiation) have limited destructive effects on cyanobacterial cell membranes and intracellular biomolecules, resulting in poor algae suppression and allowing algal cells to proliferate and re-emerge within a short period.

[0004] Therefore, there is an urgent need to develop an algae removal method that can efficiently inactivate algal cells, effectively inhibit their regeneration, and have a long-term algae control effect. Summary of the Invention

[0005] This application aims to provide an algae removal method based on the synergistic effect of dual-wavelength ultraviolet light, in order to solve the technical problems that are common in existing algae removal technologies, such as low algae removal efficiency, easy reactivation of algae cells, difficulty in maintaining treatment effect, and insufficient long-term algae control stability.

[0006] To achieve the above objectives, this application provides the following technical solution: A dual-excimer ultraviolet synergistic algae removal method includes the following steps: The algae-containing water to be treated is added to the ultraviolet reaction device and irradiated with the first ultraviolet light source and the second ultraviolet light source; The main emission peak wavelength of the first ultraviolet light source is 222 nm; The main emission peak wavelength of the second ultraviolet light source is 308 nm; The algae-containing water body contains cyanobacteria.

[0007] This application also provides the following technical solutions: The aforementioned dual-excimer ultraviolet synergistic algae removal method is applied in water treatment.

[0008] The technical solution provided in this application has the following beneficial effects: (1) The algae removal method provided in this application utilizes a first ultraviolet light source with a main emission peak wavelength of 222 nm and a second ultraviolet light source with a main emission peak wavelength of 308 nm for synergistic irradiation. The first ultraviolet light source destroys the integrity of algal cell membranes and the activity of intracellular reactive oxygen species scavenging enzymes, and the second ultraviolet light source generates more intracellular ROS to further damage nucleic acid structures. This forms a multi-site synergistic destructive effect on algal cell membrane system, antioxidant defense system and genetic material, which significantly improves the inactivation efficiency and inactivation depth of algal cells.

[0009] (2) The algae removal method provided in this application can significantly reduce the reactivation rate of algae cells while achieving rapid inactivation of algae cells, thereby improving the durability of algae removal effect and the stability of long-term algae control.

[0010] (3) The algae removal method provided in this application does not require the addition of any chemical agents, thus avoiding the risk of secondary pollution and algal toxin release that may be caused by chemical algae removal. It has the advantages of being green and environmentally friendly, easy to operate, and easy to integrate with existing water treatment processes, and has broad prospects for promotion and application. Attached Figure Description

[0011] Figure 1 The changes in chlorophyll (a) and photosynthetic activity (b) of Microcystis aeruginosa with UV irradiation dose (C t This indicates the chlorophyll content of algal cells after treatment with the current ultraviolet irradiation dose; C0 indicates the chlorophyll content of algal cells without irradiation; Fv This indicates the photosynthetic activity level of algal cells after treatment with the current ultraviolet irradiation dose; F m (This indicates the photosynthetic activity level of algal cells that have not been irradiated).

[0012] Figure 2 This indicates the recovery status of algal cells (chlorophyll content).

[0013] Figure 3 The change in the number of intact membrane cells in algae with UV222 + UV308 irradiation dose (C0 represents the number of unirradiated intact membrane cells, C... t This represents the number of intact membrane cells after treatment with the current UV irradiation dose.

[0014] Figure 4 The content of SOD and CAT after UV222+UV308 treatment (relative to the blank group).

[0015] Figure 5 The percentage of ROS-positive algal cells after ultraviolet irradiation treatment. Invention Details In this application, numerical ranges can be represented by a hyphen "-" or a tilde "~". Unless otherwise stated, the range should be understood to encompass both the endpoint values ​​and any values ​​between the endpoints. There are no particular restrictions on the numerical types within the range, including but not limited to integers, decimals, fractions, percentages, etc., unless explicitly excluded by the context or a particular numerical type is technically unavailable. The numerical types within the range are not limited by the specific representation of the endpoints.

[0017] In this application, the terms "including," "containing," and similar expressions have a non-restrictive meaning.

[0018] The term "pretreatment" as used herein refers to conventional water treatment procedures performed before ultraviolet (UV) irradiation, based on the water quality characteristics of the algae-containing water body to be treated. For example, pretreatment includes, but is not limited to, any one or more of the following: screen filtration, sedimentation, pre-oxidation, pH adjustment, and coagulation. The purpose of pretreatment is to remove suspended particulate matter, large floating objects, and other impurities that may affect UV light penetration efficiency, or to adjust the physicochemical properties of the water body to optimize the algae removal effect of subsequent UV irradiation. Pretreatment may not be necessary if the algae-containing water body to be treated meets the conventional conditions for UV irradiation treatment.

[0019] One embodiment of this application is as follows: A dual-excimer ultraviolet synergistic algae removal method includes the following steps: The algae-containing water to be treated is added to the ultraviolet reaction device and irradiated with the first ultraviolet light source and the second ultraviolet light source; The main emission peak wavelength of the first ultraviolet light source is 222 nm; The main emission peak wavelength of the second ultraviolet light source is 308 nm; The algae-containing water body contains cyanobacteria.

[0020] In some specific implementations, the first ultraviolet light source is a KrCl excimer lamp.

[0021] In some specific implementations, the second ultraviolet light source is an XeCl excimer lamp.

[0022] In some specific implementation schemes, both the first ultraviolet light source and the second ultraviolet light source are water-immersed cylindrical lamp tubes.

[0023] In some specific implementations, the irradiance of the first ultraviolet light source is 0.1-1.0 mW / cm². 2 The preferred value is 0.35 mW / cm 2 .

[0024] In some specific implementations, the irradiance of the second ultraviolet light source is 0.1-1.5 mW / cm². 2 The preferred value is 0.42 mW / cm 2 .

[0025] In some specific implementations, the total irradiation dose of the first and second ultraviolet light sources is 10-200 mJ / cm². 2 Preferably 20-50 mJ / cm 2 .

[0026] In some specific implementations, the ratio of the irradiation dose of the first ultraviolet light source to that of the second ultraviolet light source is 1:(1-1.5), more preferably 1:1.2.

[0027] In some specific implementations, the first ultraviolet light source and the second ultraviolet light source irradiate simultaneously or alternately.

[0028] In some specific implementations, the cyanobacteria are one or more of the genera Microcystis, Chromocystis, Synechocystis, Cynocystis, and Coelophyta.

[0029] In some specific implementations, the cyanobacteria are one or more species of the genus Microcystis.

[0030] In some specific implementation schemes, the cyanobacteria are one or more of the following: Microcystis aeruginosa, Microcystis sinensis, Microcystis algal bloom, Microcystis radiata, Microcystis solidus, Microcystis flocculation, Microcystis nervosa, Microcystis nervosa, Microcystis candida, Microcystis smithii, Microcystis viridans, and Microcystis whitney.

[0031] In some specific implementation schemes, the cyanobacteria density of the algae-containing water body is greater than zero and does not exceed 1.0 × 10⁻⁶.7 Cells / mL, preferably not exceeding 1.0 × 10⁻⁶. 5 per mL.

[0032] In some specific implementations, the turbidity of the algae-containing water body does not exceed 5 NTU, preferably not more than 1 NTU.

[0033] In some specific implementations, the ultraviolet reaction device is an intermittent cylindrical reactor with a built-in ultraviolet light source.

[0034] Another implementation scheme of this application is as follows: The application of any of the aforementioned dual-excimer ultraviolet synergistic algae removal methods in water treatment; wherein the algae-containing water body is surface water.

[0035] In some specific implementation plans, the surface water is a eutrophic water body.

[0036] In some specific implementation plans, the surface water is lake water or reservoir water.

[0037] In some specific implementation schemes, the algae-containing water body is pretreated before irradiation. Detailed Implementation

[0038] The following specific embodiments are used to further describe the implementation of the present invention and do not limit the scope of the present invention.

[0039] Example 1 Microcystis aeruginosa was selected as the target algal species for large-scale cultivation. After the Microcystis aeruginosa was cultured to the exponential growth phase, the algal culture was centrifuged, the supernatant was discarded, and the cells were resuspended in ultrapure water to adjust the final cell density to approximately 1.0 × 10⁻⁶. 5 The algae-containing water sample was obtained by measuring algae per mL to simulate the actual algal bloom state. The turbidity of the obtained algae-containing water sample was 0.9 NTU.

[0040] The aforementioned algae-containing water sample was added to a UV reaction apparatus and simultaneously irradiated with a KrCl excimer lamp with a main peak wavelength of 222 nm and a XeCl excimer lamp with a main peak wavelength of 308 nm. The UV reaction apparatus was an intermittent cylindrical reactor with a volume of 350 mL. The UV light sources (UV222 and UV308) were both water-immersed cylindrical lamps, installed side-by-side inside the reaction apparatus, each with its own independent power supply and adjusted irradiance. Irradiation was conducted at room temperature. The UV light intensity was measured using the KI / KIO3 chemiphotometric method, and the calculated UV222 light intensity was 0.35 mW / cm². 2 The UV308 light intensity is 0.42 mW / cm². 2 The ultraviolet dose is controlled by adjusting the irradiation time, with each irradiation providing 10 mJ / cm² of ultraviolet light. 2A sample was then taken, with a volume of 1 mL and a total irradiation dose of 50 mJ / cm². 2 .

[0041] Comparative Example 1 The algae-containing water sample to be treated was obtained according to the method in Example 1, and then added to an ultraviolet reaction device for irradiation using a KrCl excimer lamp with a main peak wavelength of 222 nm. The ultraviolet light intensity was measured using the KI / KIO3 chemiphotometric method, and the calculated UV222 light intensity was 0.35 mW / cm². 2 The ultraviolet dose is controlled by adjusting the irradiation time, with each irradiation providing 10 mJ / cm² of ultraviolet light. 2 A sample was then taken, with a volume of 1 mL and a total irradiation dose of 50 mJ / cm². 2 .

[0042] Example 2 The chlorophyll content and photosynthetic activity of algal solutions (algae-containing water samples irradiated according to Example 1 or Comparative Example 1) were measured using a phytoplankton fluorometer to evaluate changes in the physiological activity of algal cells. Chlorophyll content characterizes the biomass level of algal cells, while photosynthetic activity characterizes the degree of damage to the algal cell photosystem and its metabolic activity. Lower chlorophyll content and photosynthetic activity indicate more severe UV damage and a higher degree of inactivation of the algal cells.

[0043] result( Figure 1 The results showed that both UV222 irradiation alone and synergistic irradiation with UV222 and UV308 reduced chlorophyll content in algal slurry and weakened photosynthetic activity. In particular, synergistic irradiation with UV222 and UV308 had a more significant effect on reducing chlorophyll content in algal slurry, and could achieve this with a lower total radiation dose (20 mJ / cm²). 2 The complete inhibition of photosynthetic activity was achieved under UV222, indicating that irradiation treatment in combination with UV308 on the basis of UV222 can more effectively inhibit algal cell activity and remove algal cells.

[0044] Example 3 This embodiment conducts a reactivation inhibition experiment. The UV222+UV308 treatment group (Example 1, 20 mJ / cm²) was subjected to ultraviolet irradiation. 2 UV222 treatment group (Comparative Example 1, 20 mJ / cm) 2 Algal solutions from both the control group (without UV irradiation) and the untreated control group were added to BG11 medium and cultured in a light incubator for 7 days. The conditions for recovery culture were: temperature 25±1℃, light intensity 2000 lux, and light-dark cycle 12h:12h. During the culture period, chlorophyll content of the algal solutions was measured every 24 hours to evaluate the inhibitory effects of UV222 and UV222+UV308 irradiation on algal cell reactivation. Results ( Figure 2 The results showed that, compared with the control group, the chlorophyll recovery of algal cells in the UV222 treatment group and the UV222+UV308 treatment group was slow, indicating that algal cell growth was inhibited. In particular, the inhibitory effect of the UV222+UV308 treatment group on algal cell regeneration was significantly higher than that of the UV222 treatment group.

[0045] Example 4 The UV222+UV308 treatment group (Example 1, 10-50 mJ / cm) was detected using the SYTOX Green staining method. 2 The integrity of algal cell membranes in the control group and the stained algal solution were also assessed. The stained algal solution was analyzed using a fluorescence microscope or flow cytometry, and the changes in the number of cells with intact cell membranes were recorded.

[0046] result( Figure 3 The results showed that after synergistic irradiation treatment with UV222 and UV308, the number of cells with intact cell membranes in the algal solution decreased and the membrane permeability increased.

[0047] Example 5 This embodiment describes the detection of ROS scavenging enzyme activity. Algal cells from the blank group, the UV222+UV308 treatment group (Example 1), and the UV222 treatment group (Comparative Example 1) were collected, prepared into cell homogenates, and the supernatant was collected by centrifugation for detection. The relative contents of superoxide dismutase (SOD) and catalase (CAT) were determined using an enzyme-linked immunosorbent assay (ELISA) kit to evaluate the effect of synergistic UV222+UV308 irradiation on the algal cell ROS scavenging enzyme system.

[0048] The results showed that, compared with the control group, the levels of SOD and CAT in algal cells irradiated by synergistic UV222 and UV308 were significantly decreased. Figure 4 20 mJ / cm 2 This indicates that the ROS scavenging enzyme system was inhibited. Furthermore, the percentage of ROS-positive algal cells in the UV222+UV308 treatment group ( Figure 5 The concentrations of ROS in the UV222+UV308 group were significantly higher than those in the UV222 treatment group, indicating that synergistic irradiation of UV222+UV308 induced intracellular ROS accumulation. These results suggest that synergistic irradiation of UV222+UV308 can cause multi-target damage to algal cells by disrupting the cell membrane, inhibiting the ROS scavenging enzyme system, and inducing intracellular ROS accumulation.

Claims

1. A dual-excimer ultraviolet synergistic algae removal method, characterized in that, Includes the following steps: The algae-containing water to be treated is added to the ultraviolet reaction device and irradiated with the first ultraviolet light source and the second ultraviolet light source; The main emission peak wavelength of the first ultraviolet light source is 222 nm; The main emission peak wavelength of the second ultraviolet light source is 308 nm; The algae-containing water body contains cyanobacteria.

2. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, The first ultraviolet light source is a KrCl excimer lamp; the second ultraviolet light source is an XeCl excimer lamp.

3. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, Both the first and second ultraviolet light sources are water-immersed cylindrical lamp tubes.

4. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, The irradiance of the first ultraviolet light source is 0.1-1.0 mW / cm². 2 The preferred value is 0.35 mW / cm 2 The irradiance of the second ultraviolet light source is 0.1-1.5 mW / cm². 2 The preferred value is 0.42 mW / cm 2 .

5. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, The total irradiation dose of the first and second ultraviolet light sources is 10-200 mJ / cm². 2 Preferably 20-50 mJ / cm 2 ; Preferably, the ratio of the irradiation dose of the first ultraviolet light source to that of the second ultraviolet light source is 1:(1-1.5), more preferably 1:1.

2.

6. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, The first ultraviolet light source and the second ultraviolet light source irradiate simultaneously or alternately.

7. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, The cyanobacteria are one or more of the genera *Microcystis*, *Chromocystis*, *Synthia*, *Synthia*, and *Cyclocarya*, preferably one or more of the genera *Microcystis*, more preferably one or more of the genera *Microcystis aeruginosa*, *Microcystis sinensis*, *Microcystis algal bloom*, *Microcystis radiata*, *Microcystis solidus*, *Microcystis ichthyophthirius*, *Microcystis nervosa*, *Microcystis candida*, *Microcystis smithii*, *Microcystis viridans*, and *Microcystis whitney*.

8. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, The cyanobacteria density in the algae-containing water body is greater than zero and does not exceed 1.0 × 10⁻⁶. 7 Cells / mL, preferably not exceeding 1.0 × 10⁻⁶. 5 cells / mL; Preferably, the turbidity of the algae-containing water body does not exceed 5 NTU, more preferably not exceeding 1 NTU.

9. The dual-excimer ultraviolet synergistic algae removal method according to claim 1, characterized in that, The ultraviolet reaction device is an intermittent cylindrical reactor with a built-in ultraviolet light source.

10. The application of the dual-excimer ultraviolet synergistic algae removal method of claim 1 in water treatment, characterized in that, The algae-containing water body is surface water; Preferably, the surface water is a eutrophic water body; Preferably, the surface water is lake water or reservoir water; Optionally, the algae-containing water body is pretreated before irradiation.

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