Water source water algae removal method based on hydrogen peroxide-light damage synergistic effect

Abstract

The invention discloses a green and efficient algae removal method based on a light-hydrogen peroxide synergistic mechanism. According to the method, cascade amplification of exogenous chemical oxidation and algae cell endogenous oxidative stress is realized by constructing a synergistic system of visible light (500-3000 W / m) with specific intensity and hydrogen peroxide (5-50 mg / L) with gradient concentration. The action mechanism comprises the following steps: hydrogen peroxide permeation initiates algae cell lipid peroxidation; antioxidant substances such as superoxide dismutase and catalase in cells are consumed, so that the active oxygen scavenging ability is depleted; meanwhile, a photosynthetic system II is inhibited by high light intensity, light damage is accelerated, and finally programmed death of algae cells is induced. According to the method, algae can be efficiently inactivated within a short time, secondary pollution caused by dissolution of a large amount of intracellular substances is effectively avoided, hydrogen peroxide decomposition products are water and oxygen, and the method is environmentally friendly. The method is easy to operate and suitable for algae emergency control of various water bodies such as drinking water sources and landscape water bodies.

Description

Technical Field

[0001] This invention belongs to the field of water treatment and ecological restoration technology, specifically involving a novel algae removal method based on the synergistic effect of photochemical oxidation and biochemical stress. Background Technology

[0002] In recent years, rising global temperatures, coupled with issues such as substandard upstream discharges and slow water quality turnover in some river basins and reservoirs, have led to eutrophication. This has resulted in the increasing prevalence of harmful algal blooms (HABs) in inland waterways, a growing global environmental concern. The massive proliferation of algae not only significantly reduces dissolved oxygen levels in water bodies, causing large-scale mortality of aquatic organisms, but also leads to the release of foul-smelling gases by some phytoplankton, severely impacting water quality. Furthermore, the algal toxins released when algae die or rupture are often difficult to remove effectively using traditional drinking water treatment processes (such as coagulation and sedimentation) due to their hydrophilic surface, electrostatic repulsion, and steric hindrance, posing a significant risk to water supply safety.

[0003] Typically, ultraviolet (UV) light or hydrogen peroxide (H2O2) can effectively disrupt algal cell structure and reduce algal density in lakes and reservoirs. However, using either method alone has limitations: UV treatment alone is energy-intensive, H2O2 treatment alone has a long cycle, and neither can completely eliminate algal cells. Incompletely eliminated algal cells can undergo photorepair under sufficient light conditions, further damaging the water. Although the combined use of both methods can generate strong oxidizing agents—hydroxyl radicals—effectively killing algae, the excessive oxidizing power can severely damage algal cells, leading to the release of large amounts of intracellular substances (especially algal toxins) and causing secondary water pollution. Therefore, research on using a photo-H2O2 synergistic system to treat algae-contaminated water sources still faces many challenges. Summary of the Invention

[0004] In order to overcome the shortcomings and deficiencies of the prior art, the primary objective of this invention is to provide a new green and efficient algae removal method that utilizes a photo-hydrogen peroxide synergistic system.

[0005] The purpose of this invention is to provide a novel algae removal method based on the synergistic effect of photochemical oxidation and biochemical stress. This method can rapidly and effectively remove cyanobacterial cells from water bodies without causing secondary pollution due to the large-scale dissolution of intracellular substances from the algae cells. It can be used for emergency treatment of cyanobacterial blooms in contaminated drinking water and lake / reservoir water sources.

[0006] This invention provides a novel algae removal method based on a spatiotemporal synergistic mechanism of light and hydrogen peroxide. This invention utilizes a multi-level light intensity (500-3000 W / m²) system. 2This invention utilizes a spatiotemporal synergistic system of exogenous chemical oxidation and gradient H2O2 (5-50 mg / L) addition to achieve a cascade amplification effect of exogenous chemical oxidation and endogenous oxidative stress in algal cells. From a molecular mechanism perspective, this invention achieves a triple synergistic algal-killing pathway: 1) Exogenous H2O2 induces lipid peroxidation in algal cells through osmosis; 2) Algae consume large amounts of endogenous antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) to resist oxidative stress, leading to a depletion of ROS scavenging capacity; 3) High light intensity inhibits photosynthetic system II (PSII), accelerating photodamage and ultimately causing programmed cell death in algae.

[0007] Compared with the prior art, the present invention has the following beneficial effects: 1. The visible light-H2O2 synergistic technology of the present invention can efficiently inactivate algae in a short time. Compared with using H2O2 alone or light treatment alone, this synergistic technology has higher algae-killing efficiency, can induce programmed cell death in algae, and causes less damage to the algae cell structure, thereby effectively avoiding the massive dissolution of intracellular substances.

[0008] 2. The visible light-H2O2 synergistic technology adds only an appropriate amount of H2O2 to the water during the algae removal process. The main products of its decomposition are water and oxygen, which will not introduce harmful chemicals and avoid the secondary pollution that may be caused by traditional chemical algaecides (such as hypochlorous acid, chlorine dioxide, etc.).

[0009] 3. This technology is simple to operate, requiring only the addition of an appropriate amount of H2O2 to the water and the provision of a visible light source (such as sunlight or artificial light). It is suitable for algae control in various water bodies of different sizes, such as drinking water sources, landscape water bodies, and industrial cooling water systems, and is particularly suitable for water bodies with high water quality requirements. The dosage of H2O2 and the light intensity can be flexibly adjusted according to the algae density and water quality conditions of the water body to achieve the best algae removal effect. Attached Figure Description

[0010] Figure 1 The graphs show the changes over time in the removal efficiency of chlorophyll a in water by the method described in this invention under four different experimental conditions. Figure 2 Scanning electron microscope (SEM) images of cyanobacterial cells after treatment for 2.5 hours under four different experimental conditions; Figure 3 A comparison chart showing the effect of the system of the present invention on the removal rate of cyanobacteria under different hydrogen peroxide concentrations; Figure 4 A comparison chart showing the effect of the system of the present invention on the removal rate of cyanobacteria under different light intensities; Figure 5This is a comparison chart showing the effect of the system of the present invention on the removal rate of cyanobacteria at different temperatures. Detailed Implementation

[0011] The present invention will be further described below with reference to the accompanying drawings and preferred embodiments.

[0012] The following examples use Microcystis aeruginosa (Microcystis aeruginosa) Microcystis aeruginosa (represented by) , and used as the case study object, Microcystis aeruginosa The (FACHB 905) algal strain was purchased from the Freshwater Algae Culture Bank of the Chinese Academy of Sciences and was cultured on BG-1 medium. The incubator temperature was set at 25 ℃, the light intensity was 2000 Lux, the light duration was 14 h, and the dark duration was 10 h. Microcystis aeruginosa After the cells were cultured to the logarithmic growth phase, subsequent experiments began.

[0013] In the following examples, the chlorophyll a removal rate is used as an indicator of the degree of algal cell inactivation. The extraction and determination of chlorophyll a mainly refer to the People's Republic of China Water Resources Industry Standard "Determination of Chlorophyll in Water by Spectrophotometry", which will not be repeated here. Example 1

[0014] In this embodiment, the changes in algal cell surface morphology are compared by comparing four different treatment methods: light alone, H2O2 alone, visible light (isolated ultraviolet light) / H2O2, and simulated sunlight / H2O2.

[0015] Measure 100 mL of algal solution (OD680 ≈ 0.314) into a reaction vessel. The H2O2 dosage is 8 mg / L, and the light intensity is 2000 W / m². 2 The algal solution was continuously stirred, and the pH was controlled at approximately 7.2, with a temperature of 25 °C. The change in chlorophyll a during the reaction was used to represent the reaction. Microcystis aeruginosa The degree of inactivation. For example... Figure 1 The results showed that, compared with light and H2O2 treatment alone, the synergistic effect of the two greatly improved the algae removal effect.

[0016] To address the above experimental results, a visible light / H2O2 experiment was added to eliminate the influence of ultraviolet light. However, visible light radiation, even after UV filtering, unexpectedly exhibited a similar enhancing effect, indicating that UV light is not the dominant factor in the enhanced effect of visible light on H2O2. This may be because the transmembrane permeation of exogenous H2O2 leads to an increase in intracellular H2O2 concentration, amplifying the photodamage effect under high light stress, causing the photosynthetic and antioxidant systems to collapse, ultimately resulting in programmed cell death. Example 2

[0017] In this embodiment, the changes in algal cell surface morphology are compared by comparing four different treatment methods: light alone, H2O2 alone, visible light (isolated ultraviolet light) / H2O2, and simulated sunlight / H2O2.

[0018] Measure 100 mL of algal solution (OD680 ≈ 0.314) into a reaction vessel. The H2O2 dosage is 8 mg / L, and the light intensity is 2000 W / m². 2 The algal solution was continuously stirred, and the pH was controlled at approximately 7.2, while the temperature was maintained at 25 °C. SEM was used to analyze the algal solutions after 2.5 h of treatment with four different methods. Microcystis aeruginosa Take photos. For example... Figure 2 As shown, the magnification is 30,000x. No significant changes in cell surface morphology were observed after treatment with visible light or H2O2 alone, indicating that these treatments did not damage the algal cell morphology. After treatment with visible light / H2O2 and simulated sunlight / H2O2, most cell surfaces showed varying degrees of indentation, but no significant rupture. This is presumably due to the accumulation of free radicals inside the algal cells, leading to changes in cell permeability and resulting in varying degrees of shrinkage. Example 3

[0019] The effect of H2O2 concentration on algae removal efficiency was investigated in this case study, with experiments conducted at different H2O2 concentrations. The specific procedures are as follows: 100 mL of algal solution (OD680 ≈ 0.314) was measured into a reaction vessel. The H2O2 dosage was 5, 10, 15, 25, and 50 mg / L, and the light intensity was 2000 W / m². 2 The algal solution was continuously stirred, and the pH was controlled at approximately 7.2, with a temperature of 25 °C. The change in chlorophyll a during the reaction was used to represent the reaction. Microcystis aeruginosa The degree of inactivation.

[0020] The results are as follows Figure 3 As shown, the algae removal effect varies with different H2O2 concentrations. After 2.5 h of reaction, the chlorophyll a removal efficiency from highest to lowest was: 50 mg / L > 25 mg / L > 15 mg / L > 10 mg / L > 5 mg / L. No significant differences were observed under different H2O2 concentrations, suggesting that the large-scale inactivation of cyanobacteria is likely a result of the synergistic effect of light and H2O2. Example 4

[0021] The effect of temperature on algae removal efficiency was investigated in this case study, with experiments conducted at different temperatures. The specific procedures are as follows: Measure 100 mL of algal solution (OD680≈0.314) into a reaction vessel. The H2O2 dosage is 8 mg / L, and the light intensity is 2000 W / m².2 The algal solution was continuously stirred, and the pH was controlled at approximately 7.2. The temperatures were 20 ℃, 25 ℃, 30 ℃, and 35 ℃, respectively. The change in chlorophyll a during the reaction was expressed as the result. Microcystis aeruginosa The degree of inactivation.

[0022] The results are as follows Figure 4 As shown, the algae removal effect varies with temperature. After 2.5 h of reaction, the chlorophyll a removal effect is relatively similar. No significant differences were observed at different temperatures, indicating that temperature has a relatively positive effect on the system. Microcystis aeruginosa The impact on removal efficiency is minimal. Example 5

[0023] The effect of light intensity on cyanobacteria removal was investigated in this case study, with experiments conducted under different light intensities. The specific procedures are as follows: 100 mL of algal solution (OD680≈0.42) was measured into a reaction vessel. The H2O2 dosage was 8 mg / L, and the light intensity was 1000 W / m². 2 2000W / m 2 3000W / m 2 The algal solution was continuously stirred, and the pH was controlled at approximately 7.2, with the temperature at 25°C; the change in chlorophyll a during the reaction was expressed as the result. Microcystis aeruginosa The degree of inactivation.

[0024] The results are as follows Figure 5 As shown, the algae removal effect varies under different light intensities. After 2.5 hours of reaction, the chlorophyll a removal efficiency decreased from 3000 W / m² to 3000 W / m². 2 >2000 W / m 2 >1000 W / m 2 The observed significant differences under different light intensities suggest that the intracellular H2O2 concentration may be increased due to exogenous H2O2 transmembrane permeation, and the addition of light exacerbates this effect. Microcystis aeruginosa Oxidative stress in cells leads to the collapse of the photosynthetic and antioxidant systems, ultimately resulting in programmed cell death.

Claims

1. A method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage, characterized in that... Includes the following steps: Dispersing an appropriate amount of H2O2 in algae-containing water and irradiating it with a light source of a certain intensity under stirring conditions can achieve damage and programmed cell death of algae cells in a short period of time.

2. The method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage as described in claim 1, characterized in that: The wavelength range of the light radiation source is similar to that of natural light, with the main wavelength range being 290 ~ 760 nm.

3. The method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage as described in claim 1, characterized in that: The light intensity range is 1000 ~ 4000 w / ㎡, preferably 2000 w / ㎡.

4. The method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage according to claim 1, characterized in that: The range of H2O2 irradiation is 5 ~ 50 mg / L.

5. The method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage according to claim 1, characterized in that: The visible light irradiation time is 60-160 min.

6. The method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage according to claim 1, characterized in that: The algal cell concentration is 5 × 10⁻⁶. 5 ~ 5×10 7 per mL.

7. The method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage according to claim 1, characterized in that: The pH range of the algae-containing water is 6 to 9, preferably pH = 7.

8. The method for algae removal from source water based on the synergistic effect of hydrogen peroxide and photodamage as described in claim 1, characterized in that: The temperature range of the algae-containing water is 20 ℃ ~ 35 ℃, preferably 35 ℃.

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