A method for improving the algal removal effect of copper-loaded biochar

Abstract

The application discloses a method for improving the algae removal effect of copper-loaded biochar, and comprises the following aspects: 1) taking corn stalks as raw materials, and preliminarily preparing original biochar through high-temperature anaerobic pyrolysis, and then loading copper sulfate on the carrier original biochar to obtain a copper-loaded biochar algae removal agent; 2) adding a certain amount of the copper-loaded biochar into a water body in which a Microcystis aeruginosa algal bloom breaks out, and inoculating a certain proportion of an inorganic salt solution; and 3) determining the best proportion of the inorganic salt by comparing the changes of indexes such as the algae cell removal rate. The application utilizes the inorganic salt ions to increase the particle size of the copper-loaded biochar, improves the contact efficiency of the copper-loaded biochar and algae, increases the salt stress and cell membrane damage of the algae cells, and further improves the algae removal efficiency. The application inoculates the inorganic salt solution into the Microcystis aeruginosa algal liquid to strengthen the algae removal effect of the copper-loaded biochar, and can be applied to the killing of harmful blue-green algae in lakes and sewage treatment plants.

Description

Technical Field

[0001] This invention belongs to the field of aquatic ecological restoration, specifically relating to a method and application for improving the algae removal effect of copper-loaded biochar. Background Technology

[0002] The increasing eutrophication of water bodies and climate change have exacerbated the outbreaks of harmful cyanobacterial blooms in inland and coastal waters worldwide. Harmful cyanobacteria, such as Microcystis aeruginosa, which are widely distributed in water bodies, rapidly consume dissolved oxygen through respiration and secrete algal toxins into the surrounding environment, posing a serious threat to aquatic biodiversity and public health. Several relatively mature strategies and technologies exist for controlling and remediating harmful cyanobacterial blooms, including physical, chemical, and biological methods. While these technologies have potential in management and practical applications, their complexity and long onset time limit their large-scale application. In-situ chemical remediation involves applying a certain amount of algaecide to the water body experiencing an algal bloom, rapidly inhibiting algal cell growth and causing mass lysis and death of algal cells, thereby controlling the development of the bloom.

[0003] In-situ chemical remediation is mainly used in the emergency treatment of algal blooms in small and medium-sized lakes, reservoirs, sewage treatment plants, and landscape water bodies. To achieve ideal removal results, the selection of algaecides is crucial, typically requiring strong cytotoxicity or oxidizing properties. Commonly used algaecides mainly contain copper-containing products, strong oxidants, organic allelochemicals, and photocatalysts. For example, slow-release algaecides are prepared using allelochemicals such as gallic acid, coumaric acid, and salicylic acid, with natural adsorption and loading properties as carriers, to target and remove harmful cyanobacteria (CN117502450A); or modified attapulgite is used as a catalyst to activate persulfate, generating high-strength free radicals to remove cyanobacterial cells and other organic pollutants (CN113287626A).

[0004] In recent years, the research and development of new materials has led to a surge in research on optimizing the algae-removing effects of active algaecides using high-performance carrier materials. For example, using kaolin, clinoptilol, and montmorillonite as load carriers for calcium peroxide can synergistically remove phosphorus from algal bloom waters and simultaneously enhance the collision frequency between the algaecide and algal cells, adsorbing organic matter released after algal cell death (CN115490340B). Furthermore, loading p-tert-butylcatechol onto multi-walled carbon nanotubes to prepare a slow-release composite algaecide can maintain an algae removal efficiency of 98.6% after 96 hours (CN115571946A). However, the carriers used in these technologies merely endow the algaecide with new functions and properties; they cannot further enhance the final lethality and removal rate of algal cells.

[0005] When algal cells are subjected to salt stress, it directly leads to a decrease in cell growth rate, impaired cell membrane function, and even complete cell membrane damage and mass cell death. Therefore, when algal cells are subjected to the dual stress of salt and algaecides, it may enhance the final algae-removing effect of the algaecide, which will provide insights for further improving the algae-removing efficiency and final algae-removing effect of materials. However, current research and practical application results are still relatively lacking. Summary of the Invention

[0006] The purpose of this invention is to provide a method for improving the algae removal effect of copper-loaded biochar.

[0007] To achieve the above objectives, the present invention provides a method for improving the algae removal effect of copper-loaded biochar, comprising the following steps: inoculating an inorganic salt solution into a copper-loaded biochar-algae bloom liquid system to enhance the removal effect on algae blooms; wherein the copper-loaded biochar is obtained by loading copper sulfate onto raw biochar, washing, and drying; the raw biochar is a nanoscale carrier obtained by crushing, loading, high-temperature anaerobic calcination, and washing of corn stalks.

[0008] In the method described, the inoculation process involves: after colonization and expansion culture of the algal bloom seed, obtaining algae in the exponential growth phase with an algal cell density of 102... 7 For algae solutions with an algal count of 1000 cells / mL or higher, add copper-loaded biochar and inorganic salt solution and mix.

[0009] In the method described, algal colonization and expansion culture are carried out by using N2:CO2 (80:20) to remove oxygen from the liquid culture medium, followed by sterilization in an autoclave at 121°C for 15 minutes, and then inoculating the algal strain into the cooled culture medium.

[0010] In the method described, the expanded culture conditions are as follows: culture temperature is 27℃, day and night light intensity is 2000 Lux / 0 Lux, and day and night cycle is 12 hours / 12 hours. The culture medium was BG-11 medium specifically for cyanobacteria, with the following components: 1500 mg / L NaNO3, 40 mg / L K2HPO4·3H2O, 75 mg / L MgSO4·7H2O, 36 mg / L CaCl2·2H2O, 6 mg / L citric acid, 6 mg / L ferric ammonium citrate, 20 mg / L Na2CO3, 2.86 mg / L H3BO3, 1.81 mg / L MnCl2·2H2O, 0.222 mg / L ZnCl2·7H2O, 0.079 mg / L CuCl2·5H2O, 0.39 mg / L Na2MoO4·2H2O, 0.049 mg / L Co(NO3)2·6H2O, and 1 mg / L LEDTA.

[0011] In the method described, the algal bloom species is Microcystis aeruginosa.

[0012] In the method described, the inorganic salt solution is one or more of magnesium sulfate, potassium chloride, calcium chloride, and sodium sulfate.

[0013] The method described herein includes the following preparation process of copper-supported biochar: the original biochar is rinsed multiple times with deionized water, dried at 40-50℃, CuSO4·5H2O solution and original biochar powder are added according to a certain mass ratio, stirred and mixed, the solid biochar in the mud mixture is separated by filtration, the solid biochar is washed with deionized water and dried to obtain nano-sized copper-supported biochar.

[0014] The method described above involves the following process for preparing raw biochar: corn stalks are rinsed multiple times with deionized water, dried, and then crushed through a 100-mesh sieve using a plant crusher. The straw powder is then placed in a tube furnace and pyrolyzed at 400-700℃ with nitrogen gas to obtain raw biochar.

[0015] Compared with existing technologies, the advantages of this invention are: by preparing copper-supported biochar and simultaneously using non-toxic and harmless inorganic salts as reagents to enhance the algae-removing effect, both are applied together to kill Microcystis aeruginosa cells. Since inorganic salts typically have a damaging and disruptive effect on the normal biological functions of Microcystis aeruginosa cell membranes and can increase the frequency of interaction and collision between copper-supported biochar and algal cells, the removal effect on Microcystis aeruginosa is ultimately effectively improved. Attached Figure Description

[0016] Figure 1 This is a flowchart of the method for improving the algae removal effect of copper-loaded biochar according to the present invention.

[0017] Figure 2 This is a graph showing the changes in chlorophyll a concentration over 72 hours after inoculation with magnesium sulfate solutions of different concentrations.

[0018] Figure 3 This is a graph showing the changes in chlorophyll a concentration over 72 hours after inoculation with different concentrations of potassium chloride solution. Detailed Implementation

[0019] This invention provides a method for improving the algae removal effect of copper-supported biochar. The method first involves preparing copper-supported biochar and then culturing an algae culture. The specific steps are as follows:

[0020] 1) Preparation of copper-loaded biochar: Washed corn stalks were crushed using a plant crusher and passed through a 100-mesh sieve. The crushed stalks were then transferred to a tube furnace and pyrolyzed at 400-700℃ under anaerobic conditions for 1-5 hours. After natural cooling to room temperature, raw biochar with a particle size less than 0.15 mm was obtained. Subsequently, the raw biochar powder was soaked in CuSO4·5H2O solution at a mass ratio of 0.1-5.0%, and the solution was stirred for more than 6 hours using a high-speed magnetic stirrer to ensure sufficient copper loading into the nano-biochar particles. Finally, the mixture was filtered through a solvent filter and dried to obtain copper-loaded biochar powder.

[0021] 2) Algal Culture: *Microcystis aeruginosa*, a model cyanobacterial bloom species in my country, was selected. The strain was preserved at the Institute of Hydrobiology, Chinese Academy of Sciences, strain number: FACHB-905. Under aseptic conditions, the algal strain was inoculated into Erlenmeyer flasks containing sterilized BG-11 medium, and then placed in a 27℃ light incubator with the following parameters: light intensity 2000 Lux, light-dark ratio 12:12. The culture was continued until the algal cell density reached 102... 7 The culture ends when the number of cells / mL reaches a certain level.

[0022] 3) Preparation of reagents to enhance algae removal effect: Dissolve inorganic salt reagents of analytical grade or higher in deionized water at a certain ratio, and prepare a uniform inorganic salt solution by shaking at 180 rpm / min for more than 1 hour at room temperature. This solution is used to enhance the removal effect of copper-supported biochar on Microcystis aeruginosa.

[0023] 4) The prepared copper-supported biochar was inoculated into the Microcystis aeruginosa solution at a ratio of 0.5 mg / L, and an inorganic salt solution was added at a ratio of 0.5-5.0%. The synergistic effect of the toxicity between the inorganic salt and the copper-supported biochar was used to enhance the removal effect of the algaecide on Microcystis aeruginosa.

[0024] The present invention will now be described in detail with reference to specific embodiments and accompanying drawings. However, these embodiments do not limit the scope of the invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are all conventionally available commercially available raw materials and reagents.

[0025] Example 1

[0026] 1) Preparation of copper-supported biochar

[0027] The collected corn stalk biochar was rinsed multiple times with deionized water to remove surface dirt and impurities, and then dried in an oven at 50°C to constant weight. The corn stalks were then crushed using a plant crusher and passed through a 100-mesh sieve. The corn stalk powder was transferred to a tube furnace and pyrolyzed at a rate of 10°C / min from room temperature to 500°C in a nitrogen-filled atmosphere for 2 hours. After the pyrolysis process was terminated and the tube furnace was allowed to cool naturally to room temperature, nanoscale original biochar with a particle size of less than 0.15 mm was finally obtained.

[0028] Further preparation of copper-loaded biochar: First, 0.004 g of CuSO4·5H2O and 1 g of nano-biochar were added to 400 mL of deionized water to form a 1% (w / w) copper-loaded biochar. The mixture was stirred at 180 rpm for 6 hours in a magnetic stirrer to achieve complete copper loading on the nano-sized original biochar. Subsequently, the mixture was filtered through a vacuum filtration device to obtain solid biochar particles. Simultaneously, the biochar was repeatedly rinsed with deionized water to remove loosely attached salts from the surface. After drying in an oven at 40°C overnight, copper-loaded biochar was obtained.

[0029] 2) Cultivation of Microcystis aeruginosa algal blooms in water

[0030] Microcystis aeruginosa (catalog number: FACHB-905) was purchased from the Institute of Hydrobiology, Chinese Academy of Sciences (Wuhan, China). The inoculum was inoculated into Erlenmeyer flasks containing sterile BG-11 standard medium specifically for cyanobacterial growth for colonization. The temperature was set at 25°C, and the light intensity at 2000 Lx (light-dark ratio 12:12). The morphology and color of the algal solution in the Erlenmeyer flasks were monitored daily to observe for any contamination by other microorganisms. When the inoculated algal cells were in the exponential growth phase, the algal solution was harvested and diluted to 10⁻⁶. 7 cells / mL (OD) 680 The value is approximately 0.35, simulating the water body during an algal bloom.

[0031] 3) Preparation of magnesium sulfate solution

[0032] Dissolve 10g of magnesium sulfate in 1L of deionized water, then stir at high speed in a magnetic stirrer for 2 hours to obtain a homogeneous and stable magnesium sulfate solution with a concentration of 2g / L. Store the solution at 4°C for later use.

[0033] 4) Inoculation with copper-loaded biochar and magnesium sulfate solution

[0034] In this embodiment, the prepared copper-loaded biochar and magnesium sulfate solution were inoculated into simulated Microcystis aeruginosa bloom water bodies at ratios of 0.5 mg / L and 50-1000 mg / L, respectively. The cytotoxicity of copper-loaded biochar to algal cells and the stress effect of salt on the normal biological functions of algal cells were used to synergistically enhance the algae removal effect of copper-loaded biochar.

[0035] The specific method is as follows: Add 100 mL of water to each of seven 250 mL Erlenmeyer flasks. The water should be in the exponential growth phase with a cell density of approximately 10⁻⁶ cells. 7 Microcystis aeruginosa algal solutions with a concentration of cells / mL were numbered as Group 1, Group 2, ..., Group 7. 0.5 mg of copper-loaded biochar was added to each of the seven Erlenmeyer flasks containing the algal solutions. Then, 0.5 mL of 10 g / L magnesium sulfate solution was added to Group 2, 1 mL to Group 3, 2.5 mL to Group 4, 5 mL to Group 5, 7.5 mL to Group 6, and 10 mL to Group 7. The resulting magnesium sulfate concentrations from Group 2 to Group 7 were 50 mg / L, 100 mg / L, 250 mg / L, 500 mg / L, 750 mg / L, and 1000 mg / L, respectively. The Erlenmeyer flasks were manually shaken to ensure thorough mixing and contact between the algal cells, copper-loaded biochar, and magnesium sulfate solution. The conical flasks were placed in an artificial incubator to simulate the natural environment. The environmental parameters were set as follows: 25℃, light intensity of 2000 Lx (light-to-dark ratio of 12:12), and incubation time of 72 hours. During the reaction, starting from hour 0, 5 mL of algal solution was collected every 12 hours using a sterile sampler to determine its chlorophyll a concentration to characterize the removal effect of the algaecide. A total of 7 samples were collected.

[0036] result:

[0037] As shown in Table 1 and Figure 2 As shown, the chlorophyll a concentration before the reaction started was 1.39 mg / L. During the 3-day culture period, the algal cells proliferated rapidly, and the chlorophyll a concentration eventually reached 2.98 mg / L. The chlorophyll a concentration in all treatment groups gradually decreased with the extension of exposure time. The first group, which used copper-loaded biochar alone, saw a 49% decrease in chlorophyll a concentration after 3 days, indicating that the material had good algae removal effect and performance. With the increase of the magnesium sulfate inoculation ratio, the chlorophyll a removal rate gradually increased from 53.82% to 83.06% after 3 days. When the magnesium sulfate concentration after inoculation was 1 g / L, the chlorophyll a concentration was the lowest and the removal rate was the highest, indicating that the presence of magnesium sulfate improved the algae removal effect of copper-loaded biochar.

[0038] Table 1. Chlorophyll a concentration and removal rate 72 hours after inoculation with different concentrations of magnesium sulfate.

[0039] Group Magnesium sulfate concentration (mg / L) Chlorophyll a concentration (mg / L) Removal rate (%) 1 0 1.52 49.00％ 2 50 1.37 53.82％ 3 100 1.25 57.95％ 4 250 1.11 62.50％ 5 500 0.95 68.15％ 6 750 0.74 75.20％ 7 1000 0.50 83.06％

[0040] Example 2

[0041] 1) Preparation of potassium chloride salt solution

[0042] Dissolve 10g of potassium chloride in 1L of deionized water to prepare a potassium chloride salt solution with a concentration of 2g / L. Store the solution in a refrigerator at 4℃ until use.

[0043] 2) Inoculation with copper-supported biochar and potassium chloride solution

[0044] In this embodiment, the prepared copper-supported biochar and potassium chloride solution were inoculated at ratios of 0.5 mg / L and 50-1000 mg / L, respectively, into cells in the exponential growth phase with a cell density of approximately 10. 7 The algal solution of *Microcystis aeruginosa* was prepared using cells / mL. The specific method was as follows: Similar to Example 1, 0.5 mg of copper-loaded biochar was added to seven conical flasks containing algal solutions. Then, 0.5 mL, 1 mL, 2.5 mL, 5 mL, 7.5 mL, and 10 mL of 10 g / L potassium chloride solution were added to groups two through seven, respectively (corresponding potassium chloride concentrations of 50 mg / L, 100 mg / L, 250 mg / L, 500 mg / L, 750 mg / L, and 1000 mg / L). The culture time was 72 hours. During the reaction, starting from hour 0, 5 mL of algal solution was collected every 12 hours using a sterile sampler to determine its chlorophyll a concentration to characterize the removal effect of the algaecide. A total of seven samples were collected.

[0045] result:

[0046] As shown in Table 2 and Figure 3 As shown, after 3 days of cultivation, the chlorophyll a concentration in the control group algal solution increased from 1.49 mg / L to 3.17 mg / L. In the experimental group, the chlorophyll a concentration gradually decreased with increasing reaction time, indicating that copper-supported biochar can inhibit algal cell growth and remove chlorophyll a. The removal rate after 72 hours was 51.48% when copper-supported biochar was used alone. When combined with potassium chloride solution inoculation, the final removal rate of chlorophyll a ranged from 50.96% to 79.62%. The removal rate gradually increased with increasing potassium chloride concentration, reaching its maximum of 79.62% at a concentration of 1 g / L, indicating that inoculation with high-concentration potassium chloride solution can enhance the removal effect of copper-supported biochar.

[0047] Table 2. Chlorophyll a concentration and removal rate 72 hours after inoculation with different concentrations of potassium chloride.

[0048] Group Potassium chloride concentration (mg / L) Chlorophyll a concentration (mg / L) Removal rate (%) 1 0 1.54 51.48 2 50 1.55 50.96 3 100 1.41 55.38 4 250 1.26 60.30 5 500 1.02 67.83 6 750 0.81 74.57 7 1000 0.65 79.62

[0049] As can be seen from the above embodiments, the method of the present invention for improving the algae removal effect of copper-loaded biochar can effectively enhance the inhibition of Microcystis aeruginosa cell growth by copper-loaded biochar and improve the removal rate of chlorophyll a in water. Considering the algae removal effect, practicality, and application cost, the present invention is suitable for the remediation of water bodies experiencing Microcystis aeruginosa blooms.

Claims

1. A method for improving the algae removal effect of copper-loaded biochar, inoculating copper-loaded biochar and inorganic salt solution in algal liquid to enhance the algae removal effect. wherein The copper-loaded biochar is obtained by loading CuSO4·5H2O on the original biochar, washing and drying treatment, and the mass ratio of CuSO4·5H2O to biochar is 0.004:1; the inoculation ratio of copper-loaded biochar and inorganic salt solution is 0.5 mg / L and 50-1000 mg / L, respectively. The original biochar is a nanoscale carrier obtained by rinsing, crushing, charging and high-temperature anaerobic calcination cleaning treatment of corn straw. The inorganic salt solution is one or several of magnesium sulfate, potassium chloride, calcium chloride and sodium sulfate.

2. The method of claim 1, wherein, The inoculation process is as follows: after the colonization and expansion culture of the algae species, algae liquid in the exponential growth phase with an algae cell density of 10 7 or more per mL is obtained, copper-loaded biochar and inorganic salt solution are added and mixed.

3. The method of claim 2, wherein, Algal species colonization and expansion culture are carried out by removing oxygen in the liquid medium with N2:CO2=80:20, sterilizing in an autoclave at 121°C for 15 min, and then inoculating the algal species into the cooled medium.

4. The method of claim 3, wherein, The expansion culture conditions are as follows: the culture temperature is 27°C, the day-night light intensity is 2000 Lux / 0 Lux, and the day-night cycle is 12 hours / 12 hours; the culture medium is BG-11 medium specially used for cyanobacteria, and the composition is 1500 mg / L NaNO3, 40 mg / L K2HPO4·3H2O, 75 mg / L MgSO4·7H2O, 36 mg / L CaCl2·2H2O, 6 mg / L citric acid, 6 mg / L ferric ammonium citrate, 20 mg / L Na2CO3, 2.86 mg / L H3BO3, 1.81 mg / L MnCl2·2H2O, 0.222 mg / L ZnCl2·7H2O, 0.079 mg / L CuCl2·5H2O, 0.39 mg / L Na2MoO4·2H2O, 0.049 mg / L Co(NO3)2·6H2O and 1 mg / L EDTA.

5. The method of claim 2, wherein, The algal species is Microcystis aeruginosa.

6. The method of claim 1, wherein, The preparation process of copper-loaded biochar is as follows: The original biochar is rinsed with deionized water for multiple times, dried at 40-50°C, and then CuSO4·5H2O solution and original biochar powder are added in a certain mass ratio and stirred to mix, the mass ratio of CuSO4·5H2O to biochar is 0.004:1, the solid biochar in the slurry mixture is separated by suction filtration, the solid biochar is washed with deionized water, and then dried to obtain nanoscale copper-loaded biochar.

7. The method of claim 6, wherein, The preparation process of original biochar is as follows: corn straw is rinsed with deionized water for multiple times, dried, crushed with a plant crusher to pass through a 100-mesh sieve, and then pyrolyzed in a tube furnace by passing nitrogen at 400-700°C to obtain original biochar.

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