Method for treating red tide by seawater micro-electrolysis to improve flocculation and sedimentation of clay

Abstract

The present application belongs to the technical field of red tide prevention and control, and particularly relates to a method for improving the flocculation and sedimentation of clay to treat red tide by seawater micro-electrolysis. The method for improving the efficiency of clay in treating red tide by micro-electrolysis is to apply the clay treated by micro-electrolysis to the sea area to be treated, so that the red tide organisms in the sea area can be removed. The efficiency of removing red tide organisms of the clay suspension liquid prepared by seawater and subjected to micro-electrolysis is much higher than that of the clay suspension liquid without electrolysis, is significantly higher than that of only electrolyzing seawater, and is also significantly higher than the sum of the removal rates of red tide organisms of the two. Therefore, compared with only using clay to remove algae, the method for treating red tide by micro-electrolyzing the clay suspension liquid can effectively reduce the dosage of clay in the water body; compared with only electrolyzing to remove algae, the method can reduce the introduction of algicidal active substances.

Description

Technical Field

[0001] This invention belongs to the field of red tide control technology, specifically a method for controlling red tides by improving clay flocculation and sedimentation through seawater micro-electrolysis. Background Technology

[0002] Red tides are ecological disasters caused by the abnormal proliferation or accumulation of algae in seawater, leading to large-scale discoloration of seawater and toxic or harmful effects on fish, birds, shellfish, shrimp, marine mammals, and humans. In recent years, with global climate change and increased human activities, red tide outbreaks have shown a trend of increasing frequency, wider impact, and more severe damage, urgently requiring efficient control methods.

[0003] Clay flocculation sedimentation is one of the few technologies currently available, both domestically and internationally, that can be applied on a large scale to the on-site management of red tide disasters. The principle of this method is that clay minerals collide and combine with red tide organisms in the water, rapidly flocculating and settling to the bottom, reducing the density of red tide organisms in the water. This method has advantages such as wide availability of materials, low cost, and safe use. However, it suffers from low algae removal efficiency and requires large amounts of clay. In recent years, electrolysis technology has begun to be applied to small-scale research on the eradication of red tide organisms. Existing electrolysis methods for removing red tide organisms use DC power as an energy source, utilizing a strong electric field to ionize H2O and O2 to generate a high-concentration hydroxyl radical solution, which acts on the red tide organisms, killing them. This method has a good algae-killing effect, but forming a strong electric field capable of ionizing H2O and O2 requires ultra-high voltage conditions. This not only requires a large amount of energy but also poses certain safety hazards during operation. Furthermore, the direct application of high doses of hydroxyl radicals to open water poses a potential risk of secondary ecological damage. Currently, electrolysis is only used to kill red tide organisms in small bodies of water in some special scenarios, such as ballast water and industrial condensate. Summary of the Invention

[0004] The purpose of this invention is to combine electrolysis technology and clay technology to provide a method for controlling red tides by improving clay flocculation and sedimentation through micro-electrolysis.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for improving the efficiency of clay in controlling red tides through micro-electrolysis involves applying micro-electrolyzed clay to the sea area to be treated, thereby removing red tide organisms from the sea area.

[0007] The clay is natural inorganic clay with particles smaller than 100 μm or modified natural inorganic clay.

[0008] The natural inorganic clay is one or more of kaolin, montmorillonite, and silica.

[0009] The clay treated by micro-electrolysis is prepared by mixing the clay with seawater to form a clay suspension with a concentration of 5-50 g / L, and then treating it by micro-electrolysis.

[0010] The micro-electrolysis uses a voltage of 5-50V and a current of 10-1000mA / cm. 2 Electrolysis time is 1-20 minutes.

[0011] The amount of clay applied after micro-electrolysis treatment is 0.05-0.5 g / L.

[0012] Advantages of this invention:

[0013] This invention utilizes micro-electrolysis of a clay suspension prepared with seawater. The resulting efficiency in removing red tide organisms is significantly higher than that of an unelectrolyzed clay suspension, significantly higher than that of seawater electrolysis alone, and significantly higher than the combined removal rates of both. Therefore, micro-electrolysis of clay suspension for red tide control effectively reduces the amount of clay added to the water compared to clay-based algae removal alone; and compared to electrolysis-based algae removal alone, it reduces the introduction of algicidal active substances.

[0014] This invention employs micro-electrolysis under low voltage and low current conditions when electrolyzing clay suspensions. Compared to high-voltage electrolysis, micro-electrolysis offers lower energy consumption and better safety. Seawater is used as the electrolyte in the micro-electrolysis process, utilizing locally available materials.

[0015] Seawater undergoing micro-electrolysis can generate highly reactive free radicals and oxidizing agents such as hypochlorite and hydrogen peroxide. Direct application of these to red tide waters can easily cause oxidative damage to other organisms. This application combines micro-electrolysis and clay technology, first preparing an electrolytic clay suspension, which is then sprayed onto the red tide water. The reactive free radicals generated in the suspension are rapidly quenched in the electrolysis equipment before spraying, while algicidal active substances such as sodium hypochlorite and hydrogen peroxide are adsorbed and accumulated on the clay surface in large quantities. This combined approach improves the algae-removing efficiency of the clay while eliminating reactive free radicals and effectively reducing the presence of free sodium hypochlorite, hydrogen peroxide, and other algicidal active substances in the water, thus mitigating the ecological risks associated with spraying into red tide waters. Attached Figure Description

[0016] Figure 1 The figure shows the effect of microelectrolysis of clay suspension provided in the embodiments of the present invention on the removal efficiency of red tide organisms.

[0017] Figure 2 The diagram shows the removal efficiency of red tide organisms by electrolyzed seawater and electrolyzed kaolin suspension provided in the embodiments of the present invention.

[0018] Figure 3The diagram illustrates the effect of clay particles and liquid components in the micro-electrolytic clay suspension provided in this embodiment of the invention on the removal of red tide organisms.

[0019] Figure 4 The figure shows the effect of microelectrolysis of clay suspension provided in the embodiments of the present invention on the removal rate of red tide organisms.

[0020] Figure 5 The effect of clay type on the efficiency of red tide removal by micro-electrolysis clay suspension provided in the embodiments of the present invention. Detailed Implementation

[0021] The following examples further illustrate specific embodiments of the present invention. It should be noted that the specific embodiments described herein are merely for illustration and explanation and are not intended to limit the scope of the present invention.

[0022] This invention combines electrolysis technology with a clay method. It utilizes seawater to prepare a clay suspension, which is then subjected to micro-electrolysis before spraying. This micro-electrolysis generates algicidal active substances, which are partially enriched on the clay surface. This achieves highly efficient algae removal with low clay dosages while also being environmentally friendly. Furthermore, the presence of clay significantly reduces the amount of electrolytic active substances required for algae removal, lowers electrolysis energy consumption, and reduces ecological risks, making it a promising candidate for large-scale application in red tide control.

[0023] Example 1

[0024] Two 1g portions of kaolin were weighed and added to 100mL of nearshore Yellow Sea seawater filtered through a 0.45μm membrane to prepare two 10g / L kaolin suspensions. One of the kaolin suspensions was placed in an electrolytic cell for electrolysis. The electrolysis conditions were: Pt electrodes for both anode and cathode, an electrolysis pressure of 10V, and a current density of 0.49A / cm². 2 The electrolysis time is 5 minutes.

[0025] Heterosigma akashiwo, a red tide algae in its growth plateau phase, with a cell density of approximately 8.5 × 10⁻⁶ cells, was collected. 6 Add (cells / L) to 25 mL colorimetric tubes, then add unelectrolyzed kaolin suspension and electrolyzed kaolin suspension respectively, to make the concentration of kaolin suspension in the system 0.04, 0.08, 0.12, 0.16, 0.20 and 0.24 g / L. Shake well and let stand for 3 hours, then calculate its algae removal efficiency (see [reference]). Figure 1 ).

[0026] The calculation method for the red tide organism removal efficiency of modified clay is as follows:

[0027]

[0028] In the formula, R is the removal efficiency, and N is the removal efficiency. t N represents the number of algal cells in the supernatant after settling in the experimental group. c The number of algal cells in the supernatant of the control group after standing is shown.

[0029] Figure 1 The results showed that the removal efficiency of kaolin suspension after micro-electrolysis was significantly improved for Heterosigma erythrorhizoma compared with that of unelectrolyzed kaolin suspension. This result indicates that micro-electrolysis of the clay suspension produced some algicidal active substances, which played a certain role in promoting the removal of Heterosigma erythrorhizoma.

[0030] Example 2

[0031] A red tide heterosigma (algal cell density approximately 9.1 × 10⁻⁶) was collected during the late growth plateau phase. 7 Add (cells / L) to 25 mL colorimetric tubes, and then add unelectrolyzed kaolin suspension, electrolyzed seawater, and electrolyzed kaolin suspension, respectively. The dosages for each substance are 100 μL, 200 μL, and 300 μL. After shaking well, let stand for 3 hours to test the effect of the presence of kaolin on the removal of Heterosigma heterotruncatum by microelectrolysis (see [link to test]). Figure 2 ).

[0032] The concentration in both the unelectrolyzed and electrolyzed kaolin suspensions was 10 g / L.

[0033] The electrolyzed seawater is obtained by directly electrolyzing natural seawater, and the electrolysis conditions are as described in Example 1.

[0034] For the preparation of the electrolyzed kaolin suspension, please refer to Example 1.

[0035] Experimental results are as follows Figure 2 As shown. Figure 2 The results showed that compared with direct seawater electrolysis, the removal efficiency of micro-electrolysis of kaolin suspension for Heterosigma auriculata was significantly improved. Furthermore, the figure shows that the removal efficiency of micro-electrolysis of clay suspension for Heterosigma auriculata was significantly higher than the sum of the removal rates of seawater electrolysis alone and unelectrolyzed clay, indicating a synergistic effect between the algicidal active substances generated in the micro-electrolysis of clay suspension and the clay itself.

[0036] Example 3

[0037] A red tide heterosigma (algal cell density approximately 1.1 × 10⁻⁶) was collected during the late growth plateau phase. 8Add cells / L) to a 25 mL colorimetric tube, then add unelectrolyzed kaolin suspension, filtrate after electrolysis to remove kaolin, and kaolin resuspension after electrolysis to remove filtrate. Each substance was added in doses of 100 μL, 200 μL, and 300 μL. After shaking well, let stand for 3 hours and compare the removal efficiency of Heterosigma erythrorhizoma after adding the three substances.

[0038] The electrolysis conditions for the kaolin suspension in the experiment were the same as in Example 1. Both the unelectrolyzed and electrolyzed kaolin suspensions were 10 g / L. The electrolyzed kaolin suspension was filtered through a 0.22 μm mixed-fiber membrane to obtain a filtrate after kaolin removal. The kaolin retained on the mixed-fiber membrane was then re-selected with seawater to prepare a 10 g / L electrolyzed kaolin resuspension. The concentrations of the unelectrolyzed kaolin suspension, the filtrate after kaolin removal, and the kaolin resuspension after filtrate removal were set at 4 mL / L, 8 mL / L, and 12 mL / L, respectively. The experimental results are as follows: Figure 3 As shown in the figure. The results indicate that, compared with the unelectrolyzed kaolin suspension, the algae removal efficiency of the electrolyzed kaolin resuspension was still significantly higher. This result suggests that the kaolin surface has a certain adsorption and enrichment effect on the algicidal active substances generated by micro-electrolysis.

[0039] Example 4

[0040] A sample of *Heterosigma erythroplasma* at its growth plateau stage (algal cell density approximately 8.5 × 10⁻⁶) was collected. 6 Add cells / L) to a 25 mL colorimetric tube, add the unelectrolyzed kaolin suspension and the electrolyzed kaolin suspension described in Example 1, shake well, monitor the dynamic changes in the number of algal cells of Heterobacter erythrorhizon in the supernatant, and calculate its algae removal efficiency.

[0041] The control group and experimental group were respectively given 0.20 g / L of unelectrolyzed and electrolyzed kaolin suspension, and samples were continuously monitored and taken. The sampling time is as follows: Figure 4 .

[0042] Figure 4 The results showed that after spraying a 0.20 g / L unelectrolyzed kaolin suspension onto the red tide water, the removal rate of red tide organisms did not fully stabilize after 180 minutes. However, when using 0.20 g / L electrolyzed kaolin to remove red tide organisms, most of the organisms were removed within 15 minutes of spraying; the algae removal efficiency stabilized after only about one hour. These results indicate that electrolysis of kaolin can significantly reduce the time required for algae removal and significantly improve the algae removal rate.

[0043] Example 5

[0044] A sample of *Heterosigma erythroplasma* in its logarithmic growth phase (algal cell density approximately 8.5 × 10⁻⁶) was collected. 6Add (cells / L) to 25 mL colorimetric tubes, then add unelectrolyted kaolin suspension, electrolyzed kaolin suspension, electrolyzed montmorillonite suspension, and electrolyzed silica suspension respectively. Shake well and let stand for 3 hours. Calculate the algae removal efficiency (see [reference]). Figure 5 ).

[0045] All clay suspensions used in the experiment were prepared using seawater, with a concentration of 10 g / L. The electrolysis conditions for each clay suspension were the same as in Example 1. After different types of clay suspensions were added to the red tide water, their concentration gradients in the water were set to 0.04, 0.08, 0.12, 0.16, and 0.20 g / L. The experimental results are as follows: Figure 5 As shown. Figure 5 The results showed that, compared with the unelectrolyzed kaolin suspension, the electrolyzed kaolin suspension, the electrolyzed montmorillonite suspension, and the electrolyzed silica suspension all had significantly higher algae removal efficiency.

Claims

1. A method for improving the efficiency of clay in controlling red tides through micro-electrolysis, characterized in that: The clay suspension treated with micro-electrolysis is applied to the sea area to be treated, thereby removing red tide organisms in the sea area. The clay suspension treated by microelectrolysis is obtained by preparing a clay suspension with a concentration of 5-50 g / L using seawater, followed by microelectrolysis. The microelectrolysis voltage is 5-50 V, and the current is 10-1000 mA / cm². 2 The micro-electrolysis time is 1-20 min; The clay is natural inorganic clay with particles smaller than 100μm or modified natural inorganic clay. The natural inorganic clay is one or more of kaolin, montmorillonite, and silica. The amount of clay applied after micro-electrolysis treatment is 0.05-0.5 g / L.

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