Method for treating severe cyanobacterial bloom by combination of sodium percarbonate and EM bacteria

Abstract

The present application relates to blue-green algae bloom control technical field, disclose a kind of sodium percarbonate combined with EM bacteria reinforced severe blue-green algae bloom control method, the present application uses sodium percarbonate combined with EM bacteria to control severe blue-green algae bloom, on the basis of adding sodium percarbonate 5mg / L further add EM bacteria 0.075mg / L, the algal cell density of experimental group is always lower than the control group of simply adding sodium percarbonate, and after adding sodium percarbonate 6h immediately further add EM bacteria, and the reducing effect is most remarkable, it shows that EM bacteria has the effect of reinforcing the effect of sodium percarbonate to control algae, and it is best to add EM bacteria after adding sodium percarbonate 6h, in the experimental group of adding EM bacteria 6h, algal cell density removal rate is 94.19% when experimental duration=48h, and the algal cell density removal rate of control group of only adding sodium percarbonate is only 69.77%.

Description

Technical Field

[0001] This invention relates to the field of cyanobacterial bloom control technology, specifically a method for enhancing the control of severe cyanobacterial blooms using sodium percarbonate in combination with EM bacteria. Background Technology

[0002] In recent years, under the direct and indirect influence of human activities, large amounts of nitrogen, phosphorus, and other inorganic salts from industrial wastewater, domestic sewage, lake runoff, precipitation, and aquaculture wastewater have entered slow-flowing water bodies such as ponds, reservoirs, and lakes. This has caused the water bodies to transition from an oligotrophic state with low productivity to a eutrophic state with higher productivity, resulting in eutrophication and disrupting the aquatic ecological balance. A 2019 report from the Ministry of Ecology and Environment showed that 28% of the 107 lakes and reservoirs monitored in China exhibited eutrophic characteristics, including three important water source lakes: Taihu Lake, Chaohu Lake, and Dianchi Lake, all of which were in a state of mild eutrophication. In the following years, specifically in 2021 and 2022, the proportion of eutrophic lakes increased slightly, reaching 29% and 29.9% respectively. Eutrophication in slow-flowing water bodies such as ponds, reservoirs, and lakes has intensified and often leads to algal blooms. Algal blooms are defined as the accumulation of cyanobacteria on the surface of lakes and reservoirs. Cyanobacteria, with their unique competitive advantages such as converting atmospheric nitrogen into bioavailable nutrients like ammonia, are the most common type of algal bloom. Researchers analyzed nearly 30 years of data from 70 lakes worldwide (including 12 in China) and found that cyanobacterial blooms were on the rise in 68% of these lakes, including 10 lakes in China. Surveys indicate that cyanobacterial blooms have occurred in 163 lakes and reservoirs across 28 provinces and municipalities in China. These blooms lead to decreased water transparency and dissolved oxygen, often accompanied by the production of algal toxins and odorous substances, causing water quality deterioration and damaging aquatic ecosystems. Therefore, actively researching new technologies for the control of cyanobacterial blooms is of great significance.

[0003] Traditional algae control methods include chemical, physical, and biological methods. Chemical methods can quickly kill algae, but traditional methods, such as the well-known copper sulfate method, can cause secondary pollution to the environment, such as the release of intracellular organic matter (IOM) and an increase in the concentration of heavy metal ions in the water. Physical methods have the advantages of simple operation, mature technology, and high removal efficiency, but they are generally only suitable for controlling algae in small areas of water, with low efficiency, high manpower and material consumption, and serious recurrence. Biological methods for algae control have the advantages of safety, reliability, low risk of secondary pollution, and eco-friendly growth, but they also have disadvantages such as long treatment time, potential damage to the original ecosystem, and susceptibility to many environmental factors.

[0004] Therefore, to overcome the drawbacks of traditional algae removal technologies, research on algae removal using advanced oxidation technologies (AOPs) has received considerable attention. Advanced oxidation algae removal technologies utilize conditions such as electrocatalytic oxidation, ultrasound synergy, transition metal synergy, and ultraviolet light activation to induce a chain reaction of oxidants, generating strong free radicals to achieve safe and efficient removal of cyanobacterial cells. Compared with traditional chemical methods, advanced oxidation methods for algae treatment are more efficient, greener, and produce no secondary pollution. Currently, most research focuses on advanced oxidation technologies (AOPs) that generate hydroxyl radicals (·OH), such as ultraviolet light synergy, ultrasound synergy, and electrocatalytic oxidation. However, these methods have drawbacks such as difficulty in constructing equipment and the need for regular manual maintenance, typically limiting their application to the treatment of small water bodies and making them unsuitable for large lakes and reservoirs. Cyanobacterial blooms frequently occur in large lakes and reservoirs such as Taihu Lake and Chaohu Lake, necessitating an efficient, green, and environmentally friendly treatment method for the actual management of cyanobacterial blooms in lakes and reservoirs.

[0005] Novel green and environmentally friendly oxidants such as persulfate and percarbonate are simple to add as chemical reagents. After dissolving in water, they can generate sulfate free radicals (SO4) through a series of chain reactions. - ·), hydroxyl radical (·OH), superoxide group (O2) - Potassium persulfate contains strong oxidizing groups such as ·, which can rapidly and efficiently degrade organic pollutants and quickly kill microorganisms in water. Many researchers have applied sodium percarbonate and persulfate to water treatment. For example, sodium percarbonate can be directly used to degrade organic pollutants, including benzene and trichloroethylene (TCE), while potassium persulfate, through Fe... 2+ Activation energy can effectively degrade rhodamine B dye, ketoprofen, and other substances. Meanwhile, some researchers have also applied sodium percarbonate and potassium persulfate to the control of cyanobacterial blooms. In the process of using these environmentally friendly oxidants to control cyanobacteria, researchers have found that these oxidants not only efficiently control algae but also degrade algal toxins released during normal algal metabolism and from algal death due to oxidation, thus preventing harm to human health. It is evident that novel environmentally friendly oxidants have the advantages of high efficiency, greenness, and environmental friendliness in controlling algae, therefore, the development of novel environmentally friendly oxidants for the control of cyanobacterial blooms is of great significance.

[0006] Currently, while there are numerous research findings on the use of potassium persulfate for algae control, studies on the use of sodium percarbonate are still limited. In particular, there are few comparative studies comparing the effects of both potassium persulfate and sodium percarbonate, two environmentally friendly oxidants, on cyanobacterial bloom removal. Furthermore, when using novel environmentally friendly oxidants to treat cyanobacterial blooms in slow-flowing water bodies such as ponds, reservoirs, and lakes, it is necessary to select appropriate dosages for different bloom levels to reduce costs. However, research results on appropriate dosages for different bloom levels are scarce. Therefore, addressing the shortcomings of existing research, the inventors promptly conducted a comparative study on the algae control effects of potassium persulfate and sodium percarbonate, exploring their appropriate dosages. The study revealed that sodium percarbonate exhibits superior algae control, and for severe cyanobacterial blooms, the appropriate dosage is 5 mg / L.

[0007] In addition, like other plant cells, algae can form protective enzymes, including superoxide dismutase, peroxidase, and catalase, when subjected to environmental stress. These enzymes can scavenge free radicals and reactive oxygen species to protect themselves from damage. Therefore, when using environmentally friendly oxidants to control cyanobacterial blooms, algae may relapse under the action of these protective enzymes. Thus, it is necessary to enhance the effectiveness of new environmentally friendly oxidants in controlling algae blooms. It is well known that algae must continuously absorb nutrients from their surrounding environment to maintain normal life activities. Microorganisms can inhibit abnormal algal growth by affecting nutrient cycling, causing algae to lack the N and P elements required for growth. Furthermore, using microorganisms to control cyanobacterial blooms does not produce secondary pollution, which is crucial for controlling cyanobacterial blooms in large lakes and reservoirs. However, microorganisms have drawbacks such as long treatment times when controlling cyanobacterial blooms. New environmentally friendly oxidants are highly efficient, green, and environmentally friendly in controlling algae blooms, and the two can complement each other in the process of algae control. However, existing research on the combined use of green and environmentally friendly oxidants and microorganisms for the control of cyanobacterial blooms is extremely limited. Therefore, timely research on the combined use of green and environmentally friendly oxidants and microorganisms such as lactic acid bacteria or EM bacteria to enhance and stabilize the control effect of cyanobacterial blooms is essential and has significant research value and practical application prospects. Through comparative experiments on the enhanced algae removal effects of lactic acid bacteria and EM bacteria, the inventors found that the enhanced effect of EM bacteria was more significant. The key to the combined use of EM bacteria and sodium percarbonate as an oxidant lies in the timing of their application. If applied too early, both EM bacteria and cyanobacteria will be killed or damaged by the sodium percarbonate oxidant. If applied too late, the cyanobacteria damaged by the sodium percarbonate oxidant may self-repair under the action of protective enzymes and recur as cyanobacterial blooms. In actual water body control work involving severe cyanobacterial blooms, the inventors found that the damaged cyanobacteria sank on the day of treatment but recurred the following day. Therefore, to enhance the control effect of severe cyanobacterial blooms and prevent recurrence, this invention proposes a method for enhancing the control of severe cyanobacterial blooms using sodium percarbonate in combination with EM bacteria. Summary of the Invention

[0008] The purpose of this invention is to provide a method for controlling severe cyanobacterial blooms by combining sodium percarbonate with EM bacteria. The method proposed in this invention is applicable to the control of severe cyanobacterial blooms in various stagnant water bodies such as ponds, lakes, and reservoirs. This method not only enhances the algae removal effect and prevents recurrence, but also enhances the removal of algal toxins.

[0009] To achieve the above objectives, the present invention provides the following technical solution:

[0010] This invention provides a method for treating severe cyanobacterial blooms using sodium percarbonate in combination with EM bacteria, the method comprising the following steps:

[0011] S1: Preparation of sodium percarbonate solution

[0012] At the site of treating cyanobacterial blooms, tap water or water directly from the target water body is used to dilute and dissolve the sodium percarbonate granules into a solution.

[0013] S2: Add sodium percarbonate solution

[0014] Immediately load the prepared sodium percarbonate solution into a sprayer and spray it evenly onto the water surface from a boat. If the water area is small, it can be directly and evenly sprinkled on the shore. It is important to prepare the solution while spraying, avoiding preparing a large amount at once and then spraying it slowly, as the oxidizing properties of sodium percarbonate will deteriorate over time.

[0015] S3: Add EM bacteria

[0016] EM bacteria can be added directly and evenly sprinkled into the water.

[0017] Preferably, sodium percarbonate granules are diluted and dissolved at a ratio of 1:100 to form a drug solution.

[0018] Preferably, the dosage of sodium percarbonate is calculated based on the volume of the water body to be treated, at a rate of 5 mg / L per liter of water.

[0019] Preferably, the dosage of EM bacteria is calculated based on the volume of the water body to be treated, at a rate of 0.075 mg / L per liter of water.

[0020] Preferably, EM bacteria should be added immediately 6 hours after the sodium percarbonate solution is added.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] In this invention, when sodium percarbonate is combined with EM bacteria to control algae, the algal cell density in the experimental group with added EM bacteria is consistently lower than that in the control group. The most significant reduction is observed when EM bacteria are added 6 hours after sodium percarbonate addition, indicating that EM bacteria enhance the algae-control effect of sodium percarbonate, with the optimal addition time being 6 hours after sodium percarbonate addition. In the experimental group with added EM bacteria at 6 hours, the algal cell density removal rate reached 94.19% after 48 hours of experimentation, and the algal bloom severity decreased from severe to mild, approaching zero. In contrast, the control group with only sodium percarbonate added only achieved a removal rate of 69.77%, and the algal bloom severity remained within the range of severe bloom, only approaching the boundary of moderate bloom. Furthermore, at the end of the experiment, the final algal toxin content in the control group with only sodium percarbonate was 67.10% of the initial content, with an algal toxin removal rate of 32.90%. In contrast, the algal toxin content in the experimental group with added EM bacteria was the lowest at 6 hours, only 61.06% of the initial content, with an algal toxin removal rate 6.04% higher than the control group, reaching 38.94%. This indicates that while sodium percarbonate kills large numbers of cyanobacteria cells, it not only does not cause the dead algal cells to release more algal toxins, but it can also remove some of the existing algal toxins in the water. Moreover, the addition of EM bacteria further enhances the removal of algal toxins. Attached Figure Description

[0023] Figure 1 The graph shows the change in algal cell density over time between the control group and the experimental groups that were added with EM bacteria at different times.

[0024] Figure 2 The graph shows the initial, final, and removal rates of algal toxins in the control group and the experimental groups with EM bacteria added at different times. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] This invention provides a method for treating severe cyanobacterial blooms using sodium percarbonate in combination with EM bacteria, the method comprising the following steps:

[0027] S1: On-site preparation of sodium percarbonate solution

[0028] Sodium percarbonate granules are diluted and dissolved into a solution using tap water.

[0029] S2: Add sodium percarbonate solution

[0030] Immediately and evenly sprinkle the prepared sodium percarbonate solution into the water body to be treated.

[0031] S3: Add EM bacteria

[0032] EM bacteria are directly and evenly applied to the water body being treated.

[0033] In this embodiment, the target of the treatment is a small water body experiencing a severe cyanobacterial bloom, with an initial algal cell density of 4.3*10⁻⁶. 8 cells / L.

[0034] In this embodiment, the sodium percarbonate granules are diluted and dissolved at a ratio of 1:100 to form a drug solution.

[0035] In this embodiment, the dosage of sodium percarbonate is calculated based on the volume of the water body to be treated, at a rate of 5 mg / L per liter of water.

[0036] In this embodiment, the dosage of EM bacteria is calculated based on the volume of the water body to be treated, at a rate of 0.075 mg / L per liter of water.

[0037] In this embodiment, the EM bacteria were added immediately 6 hours after the sodium percarbonate solution was added.

[0038] After 48 hours of treatment, the algal cell density removal rate reached 94.19%, and the water body was reduced from a severe algal bloom to a mild algal bloom, approaching the boundary of no obvious algal bloom. Furthermore, the algal toxin content was reduced to only 67.10% of the initial level.

[0039] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0040] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for treating severe cyanobacterial blooms using sodium percarbonate combined with EM bacteria, characterized in that: After adding sodium percarbonate, EM bacteria are added to further enhance the treatment effect of severe cyanobacterial blooms. EM bacteria were added immediately 6 hours after sodium percarbonate was added. The dosage of sodium percarbonate is 5 mg / L, which means 5 mg of sodium percarbonate is added per liter of the water body to be treated; the dosage of EM bacteria is 0.075 mg / L, which means 0.075 mg of EM bacteria is added per liter of the water body to be treated.

2. The method for treating severe cyanobacterial blooms using sodium percarbonate combined with EM bacteria as described in claim 1, characterized in that: Sodium percarbonate granules should be diluted 1:100 to form a solution and then immediately sprayed or sprinkled evenly into the water; EM bacteria should be directly sprinkled into the water.

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