A method for treating harmful algal bloom water body by in-situ strengthening an enzymatic fenton reaction system with ultraviolet light

Abstract

The application discloses a method for treating harmful algal bloom water by using an ultraviolet light in-situ reinforced enzymatic Fenton reaction system, which comprises the following steps: feeding the harmful algal bloom water into a reaction chamber, then adding glucose oxidase, glucose and green rust into the water in the reaction chamber, and applying ultraviolet light to the water in the reaction chamber to initiate a Fenton-like reaction, so that the harmful algal bloom water is treated, and the treated water is discharged from the reaction chamber. The method makes full use of the high-dissolved-oxygen environment of the harmful algal bloom water, combines the ultraviolet light with the enzymatic Fenton reaction system, controls the slow release of H2O2 in-situ, improves the types and quantity of oxidizing active substances, and improves the catalytic capacity of the enzymatic Fenton reaction system by using the ultraviolet light, so that the algae is removed in the natural water environment in a mild and efficient manner, the integrity of the algae cells is maintained to the maximum extent, and the release of intracellular organic matters is avoided.

Description

Technical Field

[0001] This invention relates to a method for treating harmful algal blooms in water bodies using an in-situ enhanced enzymatic Fenton reaction system under ultraviolet light, belonging to the field of wastewater treatment.

[0002] Background Area

[0003] Eutrophication of water bodies has become a global environmental challenge. The abnormal growth of harmful algal blooms not only leads to the death of aquatic plants and animals, but also poses a serious threat to human health due to their toxic metabolites. In recent decades, researchers have employed various methods to prevent harmful algal blooms, including physical, chemical, and biological approaches. While these methods have achieved some success in controlling cyanobacterial blooms, they generally suffer from high costs, low removal efficiency, and secondary pollution. Therefore, there is an urgent need to find an economical, efficient, and feasible algae removal method. Compared with other advanced oxidation technologies, the Fenton process is widely favored as a prominent method for algae removal due to its wide applicability, strong resistance to interference, simple operation, rapid degradation, and mineralization capabilities. In conventional Fenton algae removal technology, Fe... 2+ The Fenton reaction with hydrogen peroxide in a strongly acidic environment produces hydroxyl radicals, which can rapidly remove algae and their disinfection byproducts. However, Fe... 2+ The addition ratio of H2O2 is strictly controlled, the pH range is narrow (2~3), and Fe 2+ Low utilization rates limit the practical application of Fenton reactions in algal bloom waters. It is worth noting that the violent reaction of traditional Fenton reactions causes rapid rupture of algal cells, releasing large amounts of intracellular organic matter into the environment, triggering a series of disinfection byproducts and causing secondary pollution. Therefore, maintaining a mild algae-removing environment, achieving a high algae removal efficiency while preserving the integrity of algal cells to the maximum extent, is key to efficient algae control. Summary of the Invention

[0004] The technical problem to be solved by this invention is to provide a method for treating harmful algal blooms in water bodies by using an in-situ enhanced enzymatic Fenton reaction system with ultraviolet light, which addresses the shortcomings of the existing technology. This method fully utilizes the high dissolved oxygen environment of the harmful algal bloom water body and combines ultraviolet light with the enzymatic Fenton reaction system. While controlling the slow release of H2O2 in situ, it can not only increase the types and quantities of oxidative active substances, but also enhance the catalytic ability of the enzymatic Fenton reaction system with ultraviolet light, thereby achieving mild and efficient algae removal in natural water body environment, maximizing the preservation of algal cell integrity and avoiding the release of intracellular organic matter.

[0005] The technical solution adopted by the present invention to solve the above-mentioned problems is as follows:

[0006] A method for treating harmful algal bloom water bodies using an in-situ enhanced enzymatic Fenton reaction system under ultraviolet light is described below. The specific process is as follows: the harmful algal bloom water body is sent into a reaction chamber, glucose oxidase, glucose, and green rust are added to the water body in the reaction chamber, and ultraviolet light is applied to the water body in the reaction chamber to initiate a Fenton-like reaction, thereby treating the harmful algal bloom water body. The treated water body is then discharged from the reaction chamber.

[0007] According to the above scheme, the harmful algal bloom water body is natural harmful algal bloom wastewater (or natural algae-containing wastewater, natural algae-containing sewage), with an algal cell density of 1.5 × 10⁻⁶. 7 ~1.5×10 8 The concentration of cells / ml is 5-9 (preferably pH 6-8, with the most preferred pH around 7), and the dissolved oxygen concentration is 6-8 mg / L.

[0008] According to the above scheme, the wavelength of ultraviolet light is 300~400nm, and the intensity of ultraviolet light is 250~350uW / cm. 2 .

[0009] According to the above scheme, the dosage of green rust, glucose and glucose oxidase are all calculated per liter of water. The dosage of green rust is 10~30 mL / L, the dosage of glucose is 60~90 mmol / L, and the dosage of glucose oxidase is 5~20 mmol / L.

[0010] According to the above scheme, the reaction time for harmful algal blooms in the reaction chamber is 3-5 hours. After the reaction is complete, the green rust can be recovered using a magnet.

[0011] The present invention also provides a reactor for implementing the above-mentioned enzymatic Fenton reaction system for treating harmful algal blooms in water bodies under ultraviolet conditions, comprising: an inlet pump, a reaction chamber, and an ultraviolet light generating device; wherein, the inlet pump is connected to an inlet located at the lower part of the outer wall of the reaction chamber, for pumping the harmful algal bloom water body to be treated into the reaction chamber; the ultraviolet light generating device includes an ultraviolet lamp tube installed at the center of the reaction chamber cavity; a dosing port is provided at the top of the reaction chamber, which is connected to three dosing devices containing glucose oxidase, glucose, and green rust respectively through connecting pipes; a stirring device is also provided in the reaction chamber cavity, an overflow port is provided at the upper part of the outer wall of the reaction chamber, and the outer wall of the reaction chamber is covered with a reflective film.

[0012] Furthermore, the stirring blades of the stirring device are located in the lower part of the reaction chamber.

[0013] Furthermore, the ultraviolet lamp is connected to an ultraviolet wavelength and intensity adjustment device located outside the reaction chamber. The ultraviolet lamp is positioned at the center of the reaction chamber, and its wavelength and intensity are adjusted by the ultraviolet wavelength and intensity adjustment device.

[0014] Furthermore, an outlet is provided on the bottom of the outer wall of the reactor chamber, away from the inlet, for discharging the treated water after the reaction is completed.

[0015] Furthermore, the reaction chamber is also equipped with multiple magnetic adsorption devices that can be opened and closed. By opening the magnetic adsorption devices, the green rust in the water can be adsorbed. The magnetic adsorption devices are inserted into the reaction chamber from the top.

[0016] Compared with traditional Fenton technology, the advantages of this invention are as follows:

[0017] This invention fully utilizes the high dissolved oxygen environment of harmful algal bloom water bodies, combining ultraviolet light with an enzyme-catalyzed Fenton reaction system. Without the need for external Fenton reagent, it can controllably release H2O2 in situ, increasing not only the types and quantities of oxidatively active substances, but also enhancing the catalytic ability of the enzyme-catalyzed Fenton reaction system using ultraviolet light. This achieves gentle and efficient algae removal in natural water environments, maximizing the preservation of algal cell integrity, avoiding the release of intracellular organic matter, improving reaction safety, and effectively reducing costs.

[0018] Moreover, this invention, specifically designed for wastewater from naturally occurring harmful algal blooms, maximizes its advantages in an environment of pH 7-8. Unlike traditional Fenton reactions, it eliminates the need for pre-treatment with reagents to maintain the pH at 2-3, effectively reducing treatment costs. The high dissolved oxygen environment of algal-containing wastewater provides abundant substrates for glucose oxidase catalysis, enabling in-situ slow release of H2O2 and avoiding the quenching of oxidizing active substances due to excessively high H2O2 concentrations. Furthermore, ultraviolet light significantly enhances glucose oxidase activity, reducing the concentration of glucose reactants and allowing for continuous H2O2 production even at lower reactant concentrations, thus reducing the amount of glucose oxidase required. This invention also cleverly utilizes the high dissolved oxygen environment of algal-containing wastewater, overcoming the high dissolved oxygen requirement of traditional biological enzyme Fenton systems, eliminating the need for additional aeration and minimizing costs.

[0019] In addition to generating ·OH, the system of this invention can effectively stimulate the release of harmful substances (such as algal organic matter) by algal cells, further generating a large number of reactive oxides that attack algal cells, achieving waste-to-waste treatment and breaking the traditional understanding that ultraviolet light has a negative impact on enzymatic reactions. The glucose oxidase in the system of this invention produces gluconic acid and other substances that can further become raw materials for the biochemical reaction stage, improving the biodegradability of polluted water bodies and making it environmentally friendly. The system of this invention also contains high levels of Fe in the green rust. 2+ It can effectively achieve pre-oxidation and enhanced coagulation, thus optimizing conditions for further coagulation treatment of algae-containing wastewater. Attached Figure Description

[0020] Figure 1This is a schematic diagram of the reactor used in this invention.

[0021] In the diagram: 1-Inlet pump; 2-Reaction chamber; 3-Stirring device; 4-Dosing device one, 5-Dosing device two, 6-Dosing device three, used for the addition of glucose oxidase, glucose, and green rust respectively; 7-Ultraviolet lamp tube; 8-Ultraviolet wavelength and intensity adjustment device; 9-Magnetic adsorption device; 10-Overflow port; 11-Reflective membrane; 12-Outlet; 13-Inlet; 14-Dosing port. Detailed Implementation

[0022] To better understand the present invention, the following embodiments further illustrate the content of the present invention, but the present invention is not limited to the following embodiments.

[0023] like Figure 1 As shown, the reactor used in the method of treating harmful algal bloom water bodies by the enzyme-catalyzed Fenton reaction system under ultraviolet conditions according to the present invention mainly includes: an inlet pump 1, a reaction chamber 2, and an ultraviolet light generating device; wherein, the inlet pump 1 is connected to the inlet 13 provided at the lower part of the outer wall of the reaction chamber 2, and is used to pump the harmful algal bloom water body to be treated into the reaction chamber 2.

[0024] The ultraviolet light generating device includes an ultraviolet lamp 7 installed at the center of the inner cavity of the reaction chamber 2. The ultraviolet lamp 7 is connected to an ultraviolet wavelength and intensity adjustment device 8 located outside the reaction chamber 2. The ultraviolet lamp 7 is located at the center of the reaction chamber 2. By utilizing central scattering, light attenuation and light blocking can be effectively avoided, thereby improving the utilization efficiency of light energy. The wavelength and intensity of the ultraviolet lamp can be easily adjusted by the ultraviolet wavelength and intensity adjustment device 8 to adapt to changes in reaction conditions caused by fluctuations in water quality.

[0025] The reaction chamber 2 has a dosing port 14 at its top. A stirring device 3 is also installed inside the reaction chamber 2. An overflow port 10 is located on the upper part of the outer wall of the reaction chamber 2 (to prevent excessive water in the reaction chamber), and the outer wall of the reaction chamber 2 is covered with a reflective film 11. The stirring blades of the stirring device 3 are located at the lower part of the inner cavity of the reaction chamber 2. The reflective film 11 is specifically a polyethylene terephthalate (PET) film, which can reflect ultraviolet light back into the reaction chamber 2, effectively avoiding light pollution and harm to experimental personnel. It also prevents insufficient ultraviolet light irradiation in areas near the reaction chamber wall due to light attenuation, effectively improving the uniformity of the reaction. The dosing port 14 is connected via connecting pipes to dosing devices 4, 5, and 6, which are sequentially filled with glucose oxidase, glucose, and green rust, respectively.

[0026] An outlet 12 is provided on the bottom of the outer wall of the reaction chamber 2 away from the inlet 13, which is used to discharge the treated water in the reaction chamber 2 after the reaction is completed; the inner cavity of the reaction chamber 2 is also provided with multiple magnetic adsorption devices 9 that can be opened and closed, which can adsorb green rust in the water by opening the magnetic adsorption devices 9; the magnetic adsorption devices 9 are inserted into the inner cavity of the reaction chamber 2 from the top of the reaction chamber 2.

[0027] In this invention, the target water body for treatment is a naturally occurring harmful algal bloom, preferably with an algal density of 1.5 × 10⁻⁶. 7 ~1.5×10 8 The algae concentration was 5-9 cells / ml, pH was 5-9, and dissolved oxygen was 6-8 mg / L. The main algae included cyanobacteria, diatoms, green algae, and euglena. In Example 1, the natural harmful algal bloom water body to be treated (i.e., the algae-containing wastewater to be treated) was taken from a lake in Wuhan. The pH was around 7, and the dissolved oxygen was 6-8 mg / L. The specific algal species and algal density are shown in Table 1.

[0028] Table 1. Algal species and algal density

[0029]

[0030] In the following examples, the green rust used is wet sulfate green rust, which is a transitional compound containing Fe(II) and Fe(III) with a water content of 96-97%, and is generally prepared by co-precipitation method.

[0031] Example 1

[0032] A method for treating harmful algal blooms in water bodies using an in-situ enhanced enzymatic Fenton reaction system under ultraviolet light, the specific process of which is as follows: 5L of natural algae-containing wastewater to be treated is introduced into the inlet 13 of reaction chamber 2 (the effective reaction volume of reaction chamber 2 is 6L), the ultraviolet light wavelength is adjusted to 345nm, and the ultraviolet light intensity is 300uW / cm². 2 Then add 0.1 L of 500 U / mL glucose oxidase (concentration approximately 1.38 × 10⁻⁶). -8 mol / L (the molecular weight of glucose oxidase is about 160,000 Daltons), then 375 mM glucose solution was added, and the reaction was allowed to proceed for 15 min until H2O2 in the system accumulated to about 5 mM. 0.1 L of green rust was added, and the Fenton-like reaction was started. After 240 min of reaction, it flowed out from outlet 12.

[0033] During the above reaction process, samples were taken at regular intervals. Sodium thiosulfate was immediately added to the water samples taken at different time points to quench the reaction, followed by filtration and measurement of chlorophyll A. Table 1 shows the chlorophyll A removal rate in the water at different time points in Example 1. It can be seen that after 240 minutes of reaction, the chlorophyll A removal rate in the treated harmful algal bloom water reached over 90%, achieving gentle and efficient algae removal in a natural water environment. In algae removal systems, chlorophyll A is commonly used as an indicator of algal biomass; it is an essential pigment for photosynthesis in all algae.

[0034] Table 1

[0035]

[0036] Example 2

[0037] Referring to the method in Example 1, the removal rate of chlorophyll A in algae-containing wastewater under different initial pH values ​​was studied. The specific operation method was as follows: the pH of the natural harmful algal bloom wastewater to be treated was adjusted to 3, 5, 6, 7, 9, and 11, respectively. The remaining steps were the same as in Example 1.

[0038] Samples were taken periodically during the reaction. The chlorophyll A removal rate in the water at different time points in Example 2 is shown in Table 2. The results indicate that pH has a significant impact on the removal of algal cells by the system. At pH 3 and 11, the chlorophyll a removal rate of the system of this invention decreased to 48.74% and 34.52% respectively under strongly acidic or strongly alkaline conditions. Within the pH range of 5–9, the system exhibited good algal cell removal performance, with removal rates all above 71.35%. In particular, the algal cell degradation rate of the system of this invention was optimal at pH 7, reaching 91.67%.

[0039] Table 2

[0040]

[0041] Example 3

[0042] Referring to the method in Example 1, the removal rate of chlorophyll A in algae-containing wastewater with different coexisting cations was studied. The specific operation method was as follows: The following metal cations K were added to the natural harmful algal bloom wastewater to be treated. + Mn 2+ Al 3+ Cu 2+ Hg 2+ The concentration of the additive was controlled at 0.01 mmol / L, and the remaining steps were the same as in Implementation 1.

[0043] Samples were taken periodically during the reaction. Table 3 shows the chlorophyll A removal rate in the water at different time points in Example 3. It can be seen that K... +It has virtually no impact on the removal of Microcystis aeruginosa. Mn 2+ And Al 3+ The introduction of Cu enhanced the system's ability to degrade chlorophyll a; 2+ and Hg 2+ This resulted in varying degrees of inhibition of the removal of Microcystis aeruginosa. Specifically, with the increase of Mn... 2+ And Al 3+ With the addition of Cu, the efficiency of algal cell removal in the system of this invention increased to 92.6% and 90.1%, respectively; conversely, with the addition of Cu... 2+ and Hg 2+ With the addition of [the substance], the system's effectiveness in removing algal cells decreased to 68.9% and 57.4%, respectively.

[0044] Table 3

[0045]

[0046] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the inventive concept of the present invention, and these all fall within the protection scope of the present invention.

Claims

1. A method for treating harmful algal blooms in water bodies using an in-situ ultraviolet light-enhanced enzymatic Fenton reaction system, characterized in that, The reactor used in the method includes: an inlet pump, a reaction chamber, and an ultraviolet light generator; wherein, the inlet pump is connected to an inlet located at the lower part of the outer wall of the reaction chamber, for pumping the water containing harmful algal blooms to be treated into the reaction chamber; the ultraviolet light generator includes an ultraviolet lamp tube installed at the center of the reaction chamber; a dosing port is opened at the top of the reaction chamber, which is connected to three dosing devices containing glucose oxidase, glucose, and green rust respectively through connecting pipes; a stirring device is also provided in the reaction chamber, and an outlet is provided on the bottom side of the outer wall of the reaction chamber away from the inlet, and the outer wall of the reaction chamber is covered with a reflective film; The method for treating harmful algal bloom water bodies using the aforementioned reactor with in-situ enhanced enzymatic Fenton reaction system under ultraviolet light is as follows: The harmful algal bloom water body is introduced into the reaction chamber. Glucose oxidase, glucose, and verdigris are then added to the water within the chamber. Ultraviolet light is then applied to the water to initiate a Fenton-like reaction. The reaction time is 3-5 hours, thus treating the harmful algal bloom water body. The treated water body is then discharged from the reaction chamber. The harmful algal bloom water body is natural harmful algal bloom wastewater with an algal density of 1.5 × 10⁻⁶. 7 ~1.5×10 8 Cells / ml, pH 5-9, dissolved oxygen 6-8 mg / L; UV wavelength 300-400 nm, UV intensity 250-350 μW / cm² 2 .

2. The method for treating harmful algal blooms in water bodies using an in-situ enhanced enzymatic Fenton reaction system according to claim 1, characterized in that, The green rust is wet sulfate green rust, and the dosage is 10~30mL / L; the glucose dosage is 60~90mmol / L, and the glucose oxidase dosage is 5~20U / L.

3. The method for treating harmful algal blooms in water bodies using an in-situ enhanced enzymatic Fenton reaction system according to claim 1, characterized in that, The ultraviolet lamp is connected to an ultraviolet wavelength and intensity adjustment device located outside the reaction chamber. The ultraviolet lamp is positioned in the center of the reaction chamber, and its wavelength and intensity are adjusted by the ultraviolet wavelength and intensity adjustment device.

4. The method for treating harmful algal blooms in water bodies using an in-situ enhanced enzymatic Fenton reaction system according to claim 1, characterized in that, The stirring blades of the stirring device are located in the lower part of the reaction chamber; an overflow port is provided on the upper part of the outer wall of the reaction chamber.

5. The method for treating harmful algal blooms in water bodies using an in-situ enhanced enzymatic Fenton reaction system according to claim 1, characterized in that, The reaction chamber is also equipped with multiple magnetic adsorption devices that can be opened and closed. By opening the magnetic adsorption devices, green rust in the water can be adsorbed. The magnetic adsorption devices are inserted into the reaction chamber from the top.

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