DOM-tolerant calcium salt-based microcystis algaecide and algae removal method

Abstract

The invention belongs to the field of removal of microcystis in a water body, and particularly relates to application of a crystallization system formed on the basis of Ca < 2 + > and C2O4 < 2-> in removal of microcystis in the water body, and an algaecide of salts containing Ca < 2 + > and C2O4 < 2-> crystal ions. The key point of the invention is to protect the application of a crystallization system formed by Ca < 2 + > and C2O4 < 2-> in removal of microcystis in a water body, namely the application of a CaC2O4 crystal substance in removal of microcystis in a water body. The invention further provides an algaecide containing the CaC2O4 crystal substance and application of the algaecide. After 30 days, the total removal rate of the microcystis aeruginosa can be finally kept at 95% or above, the total removal rate of the microcystis Wheatstone can be finally kept at 99% or above, and the total removal rate of the microcystis algal bloom can be finally kept at 96% or above, so that the CaC2O4 crystal has an excellent and stable removal effect on the microcystis.

Description

Technical Field

[0001] The present invention belongs to the field of removal of Microcystis in water, and specifically relates to a method based on Ca 2+ With C 2 O 4 2- The application of the formed crystal system in removing Microcystis from water bodies, and the Ca 2+ and C 2 O 4 2- Salts of these two crystal-forming ions are algaecides. Background Art

[0002] Cyanobacteria bloom is one of the most common blooms in freshwater areas. It usually refers to the phenomenon that under suitable environmental conditions and eutrophication of water bodies, cyanobacteria cells in water bodies multiply in large numbers and accumulate on the surface of water bodies to form a special blue-green "film coat", which causes the water body to turn blue-green. Common cyanobacteria mainly include: Microcystis, Anabaena, Oscillatoria, Aphanizomenon, etc., which have the characteristics of the widest distribution, the greatest impact, and the most serious harm. Under the background of global warming, the outbreak degree, scope, and frequency of cyanobacteria blooms have increased year by year, bringing great harm to the aquatic ecological environment. It has an impact on human health, aquatic ecosystems, and industries such as aquaculture and tourism that cannot be underestimated. Therefore, the prevention, control and governance of cyanobacteria blooms have become an environmental pollution problem that needs to be solved urgently.

[0003] Regarding the treatment method of cyanobacteria bloom, there are documents that disclose the use of calcium chloride to kill algae. For example, a certain proportion of liquid calcium chloride is added to the water to achieve the purpose of inhibiting the growth of algae. In the above method, since calcium chloride has certain toxicity, it cannot be used in excess, otherwise it will affect the water ecological environment. In addition, calcium chloride can only kill algae and cannot completely remove algae in the water, so it is necessary to check the water quality regularly and use different prevention and control methods for different types of algae. And in this application, through experiments, it is confirmed that the addition of calcium ions alone has a limited effect on the removal of Microcystis.

[0004] There are also documents that disclose the effect and mechanism of calcium carbonate crystallization in tap water to remove algae. 3 The purpose of algae removal is to remove crystals. The calcium carbonate coagulation method for algae removal still has the following problems: first, the effect is unstable for different algae; second, the effect is not ideal for natural water bodies rich in DOM. Summary of the invention

[0005] In order to solve the above technical problems, the present invention provides a method of using Ca 2+ With C 2 O 4 2-The method of removing Microcystis by forming a crystal system, considering that there will also be DOM in the water containing Microcystis, therefore, the application also investigates the influence of DOM on the process of removing algae through specific experiments. The results show that the overall removal rate of Microcystis can be maintained above 95% by the method of the present invention, and over time, CaC 2 O 4 The removal efficiency of Microcystis by crystallization was not affected by humic acid.

[0006] This application focuses on protecting Ca 2+ With C 2 O 4 2- The formed crystal system is used for removing Microcystis from water bodies.

[0007] The above-mentioned Microcystis refers to any one of Microcystis aeruginosa, Microcystis whitley, and Microcystis algae, but is not limited to the above-mentioned types. Blue algae blooms with similar characteristics to the above-mentioned Microcystis can be removed by the method of the present application.

[0008] In the above application, specifically, the Ca 2+ and C 2 O 4 2- The salts of these two crystal-forming ions are added to water containing Microcystis to achieve the purpose of inhibiting the growth of algae or removing algae.

[0009] As a preferred method, Ca 2+ and C 2 O 4 2- Finally, glucose or substances containing glucose can be added to the water.

[0010] Contains Ca 2+ and C 2 O 4 2- The calcium salt-based microcystis algaecide of the salts of these two crystal-forming ions and capable of tolerating DOM is also the focus of protection of the present invention.

[0011] Preferably, the algaecide contains CaC 2 O 4 Crystals.

[0012] The method for removing Microcystis using the algaecide comprises the following steps:

[0013] (1) Preparation of CaCl 2 Solution and Na 2 C 2 O 4 Solution;

[0014] (2) Prepared CaCl 2 Solution and Na 2 C 2 O 4 The solution was poured into the water containing Microcystis, and allowed to stand for precipitation; 2+ The concentration of C 2 O 4 2- With CaCl in (1) 2 Ca in solution 2+ The molar ratio is: 0.25~1:1.

[0015] Preferably, when CaCl is added 2 Solution and Na 2 C 2 O 4 Before the solution is added, hydrogen peroxide is added to the water at a ratio of 0.5 mL hydrogen peroxide / 200 mL water by direct addition, and allowed to stand for 2 to 3 hours. Then, CaCl 2 Solution and Na 2 C 2 O 4 Solution.

[0016] CaC 2 O 4 The crystals were used in the removal of Microcystis with excellent results. The possible reasons and mechanisms are analyzed as follows: (1) Adsorption charge neutralization theory: The surface of Microcystis cells carries a negative charge, and most of the CaC 2 O 4 The crystals carry positive charges, and the two produce an adsorption and electrical neutralization effect, which reduces the electrostatic repulsion between algae cells, making it easier for algae cells to combine and aggregate, and promoting the sedimentation of algae cells;

[0017] (2) Net-capture and sweep theory: A large number of crystal-forming ions in the algae liquid are distributed around the algae cells, forming positively charged crystal products, which attract the algae cells with negative charges on the surface to accumulate and form aggregates. When these crystal products shrink and settle, they capture and sweep the algae cells in the water;

[0018] (3) Co-flocculation: Under the influence of external forces, algal cells and crystalline products with similar particle sizes collide and aggregate with each other, forming a larger precipitate that is separated from the aqueous solution, so that the algal cells and the crystalline products are precipitated together.

[0019] Regarding the above mechanism, this application has not been deeply verified, but all experimental data show that CaC 2 O 4 The crystals are effective in removing Microcystis.

[0020] The beneficial effects of the present invention are:

[0021] (1) In this application, it was verified experimentally that CaC 2 O 4 The overall removal rate of Microcystis aeruginosa, Microcystis whitleyii and Microcystis blooms was maintained above 95% and 99% respectively in 30 days after the addition of CaC 2 O 4 Crystallization has excellent and stable effect on the removal of Microcystis. In the process of removing Microcystis, it is almost not affected by DOM, that is, it has strong tolerance to DOM.

[0022] (2) Using CaC 2 O 4 The crystals were used to remove Microcystis. For the first time, it was found that oxalate + calcium salt had a better algae removal effect. It had a good effect on three types of Microcystis blooms, especially the thick-sheathed and difficult-to-remove Microcystis. The DOM experiment confirmed that even in the case of many types of DOM and rich content, its continuous algae removal effect (30 days of effect) was still very stable. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 For single dosing of CaCl 2 The removal effect on Microcystis aeruginosa;

[0024] Figure 2 For single dosing of CaCl 2 The removal effect on Microcystis whitleyi;

[0025] Figure 3 For single dosing of CaCl 2 The removal effect on Microcystis algae;

[0026] Figure 4 For single dosing of CaCl 2 Effects of removing Microcystis on water pH;

[0027] Figure 5 For different NaC 2 O 4 :CaCl 2 The effect of comparison on the removal efficiency of Microcystis aeruginosa;

[0028] Figure 6 For different NaC 2 O 4 :CaCl 2 The effect of comparison on the removal efficiency of Microcystis whitleyi;

[0029] Figure 7 For different NaC 2 O 4 :CaCl 2 The effect of (w:w) ratio on the removal efficiency of Microcystis flos-water;

[0030] Figure 8 For different NaC 2 O 4 :CaCl 2 Effect of algae removal on water pH;

[0031] Fig. 9 CaC 2 O 4 Crystalline XRD pattern;

[0032] Fig.10 CaC 2 O 4 Crystalline IR pattern;

[0033] Fig.11 For a single component DOM to CaC 2 O 4 the impact of removing Microcystis aeruginosa;

[0034] Fig.12 For a single component DOM to CaC 2 O 4 the impact of removing Microcystis whitley;

[0035] Fig.13 For a single component DOM to CaC 2 O 4 Removal of the effects of Microcystis blooms;

[0036] Fig.14 For a single component DOM to CaC 2 O 4 Effect of water pH value on removal of Microcystis;

[0037] Fig.15 The multi-component DOM has a great influence on CaC 2 O 4 Effects of crystallization on removal of Microcystis aeruginosa;

[0038] Fig.16 The multi-component DOM has a great influence on CaC 2 O 4 Effects of crystallization removal of Microcystis whitleyi;

[0039] Fig.17 The multi-component DOM has a great influence on CaC 2 O 4 Effects of crystallization on removal of Microcystis blooms;

[0040] Fig.18 DOM to CaC within 30 days 2 O 4 Effects of crystallization to remove Microcystis;

[0041] Fig.19 CaC 2 O 4 XRD pattern of crystalline deposits;

[0042] Fig. 20 CaC 2 O 4 IR spectrum of the crystal. DETAILED DESCRIPTION

[0043] In order to enable those skilled in the art to better understand the present invention, the present invention is further described in conjunction with specific implementation methods.

[0044] In this application, Microcystis species with common algal blooms were selected as experimental objects. Microcystis aeruginosa, Microcystis whitley, and Microcystis aquaeum were purchased from the Freshwater Algae Species Bank of the Institute of Hydrobiology, Chinese Academy of Sciences (Wuhan), and the algae species numbers were FACHB-315, FACHB-908, and FACHB-1028, respectively.

[0045] Example 1

[0046] 1.1 Cultivation of Microcystis: Use BG-11 culture medium to culture Microcystis aeruginosa, Microcystis whitleyi and Microcystis aquaeum respectively. Take each component agent according to the specified amount and add it to a conical flask, dilute it with deionized water, and then seal the mouth of the conical flask with a sealing film. Move the sealed culture solution into a high-temperature steam pressure sterilizer for sterilization (temperature 121°C, time 30min), take out the culture solution after sterilization, add algae solution after the culture solution cools down, and move it into an intelligent incubator for culture (culture conditions: 25±1°C, light intensity 3000Lux, day and night ratio 12:12h, shake 3 times a day in the morning, noon and evening. Use a hemocytometer to count and monitor the growth of algae cells under a microscope, and select the algae solution in the exponential growth phase for the experiment (the absorbance A680 of the algae solution is between 0.25 and 0.45).

[0047] 1.2 Investigation of CaC 2 O 4 Algaecide effect of crystals

[0048] 1.2.1 Adding CaCl alone 2 Study on the effect of removing Microcystis

[0049] Investigate different concentrations of CaCl 2 The removal effect of CaCl 2The concentration gradient of the dosage was set to 0, 2, 4, 6, 8, and 10 mmol / L, and the water was allowed to settle for 4 h. After the precipitation was completed, a water sample was taken 3 cm below the liquid surface and the absorbance at 680 nm (A 680 ) detection, chlorophyll (Chl-a) concentration determination and pH value determination. The experimental results are shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 .

[0050] From the attached Figure 1-3 It can be seen that the removal rate of algae cells and Chl-a is due to the increase of CaCl 2 The removal rate of Chl-a was higher than that of algae cells. 2 With the increase of dosage, the removal rate of algal cells and Chl-a of Microcystis aeruginosa, Microcystis whitley and Microcystis aquae increased, but the removal effect of algal cells and Chl-a was very limited. 2 When the dosage reached 10mmol / L, the removal rates of algae cells and Chl-a were the highest, but the removal rates of Chl-a in the three algae were lower than 15%, 10%, and 20%, respectively. 2 When removing Microcystis aeruginosa, Microcystis whitleyi, and Microcystis aquae, increasing the CaCl 2 The effect of concentration on the removal rate of Microcystis aeruginosa was also very limited. Therefore, the addition of low concentration of CaCl alone was not considered. 2 Remove Microcystis aeruginosa.

[0051] from Figure 4 It can be seen that the addition of CaCl alone 2 Removal of Microcystis will reduce water pH and increase the CaCl 2 The increase in the dosage, the greater the decrease in the pH value of the water body, the lower the pH value of the water body. 2 When the dosage reached 10mmol / L, the pH value of the water body was the lowest. Compared with the pH value of the algae stock solution, the pH value of the water body decreased to 0.55 for Microcystis aeruginosa, 0.68 for Microcystis whitley, and 0.58 for Microcystis aquaticus, all of which were less than 1. 2 The pH value of the water bodies of the three types of Microcystis decreased in the following order: Microcystis whitley> Microcystis blooms> Microcystis aeruginosa. Therefore, the addition of low concentration of CaCl 2 Removal of Microcystis has little effect on the pH value of water.

[0052] 1.2.2 Different NaC 2 O 4 :CaCl 2Study on the effect of removing Microcystis under different conditions

[0053] Study on the CaCl in Microcystis aeruginosa, Microcystis whitley and Microcystis aquae 2 Under the optimal dosing concentration conditions, different NaC 2 O 4 :CaCl 2 Effect of (w:w) molar ratio on the removal efficiency of three Microcystis species, CaCl 2 Dosage concentration: Microcystis aeruginosa (6mmol / L), Microcystis whitley (8mmol / L), Microcystis aquae (8mmol / L), NaC 2 O 4 With CaCl 2 The ratio of the amount of added substances (w:w) was 0.25:1, 0.5:1, and 1:1, respectively, and the mixture was allowed to settle for 6 hours. After the sedimentation was completed, a water sample was taken 3 cm below the liquid surface and the absorbance at 680 nm (A 680 ) detection, chlorophyll (Chl-a) concentration determination, turbidity determination and pH value determination. The experimental results are shown in Figure 5 , Figure 6 , Figure 7 , Figure 8 .

[0054] The detection methods of various indicators are as follows: (1) Turbidity determination: Turbidity is one of the important criteria for measuring water quality. The turbidity of the supernatant of the water body is measured by a portable Lei magnetic (WZB-170) turbidity meter.

[0055] (2) Determination of pH value: The pH value of the water sample was measured using a Leix PHS-25 pH acidity meter.

[0056] (3) Determination of algae cell number: The algae were counted using the hemocytometer method in the early stage. The algae density obtained by the hemocytometer method was functionally related to the absorbance obtained by the spectrophotometer, and a curve between the number of algae and the absorbance was drawn. After the algae cells were fixed on the hemocytometer plate, the number of algae cells was observed and recorded using an optical microscope. The experiment was repeated three times and the average value of the three algae cell counts was taken as the final calculation result.

[0057] (4) Determination of algae density: The algae density of the solution was determined by the absorbance value of the algae solution at a wavelength of 680 nm. 680 Said; algae cell removal rate (R) = (initial A 680 -Supernatant A 680 ) / Initial A 680 ×100%; the absorbance of water was directly measured by UV-visible spectrophotometer (Q-6). Experiments have shown that the density of algae cells is related to the algae-containing water A 680There is a good linear relationship, the relationship is as follows: Microcystis aeruginosa: y = 0.1187x-0.018, R 2 =0.9992; Microcystis whitleyi: y = 0.0224x + 0.0054, R 2 =0.9992; Microcystis flos-aquae: y=0.0169x+0.005, R 2 =0.9999, so A is used 680 As a measure of algal cell density.

[0058] (5) Determination of chlorophyll concentration (μg / L): Chlorophyll (Chl-a) was directly measured using a phytoplankton classification fluorescence instrument (PPAB0168).

[0059] According to Example 1, CaCl was added separately 2 When removing Microcystis aeruginosa, the removal effect on algal cells and chlorophyll is very limited, but the use of CaC 2 O 4 When algae removal is performed by crystallization, the algae removal effect is significantly enhanced, such as Figure 5 As shown. Figure 5 (a) It can be seen that when NaC 2 O 4 With CaCl 2 When the ratio of the added substances reached 0.25:1, 0.5:1, and 1:1 respectively, the removal rates of algae cells and Chl-a were able to reach more than 95%, and the removal rates of NaC 2 O 4 :CaCl 2 When (w:w) = 0.25:1, the removal rates of algae cells and Chl-a reached 97.0% and 95.7%, respectively. 2 O 4 :CaCl 2 When (w:w) = 0.5:1, the removal rates of algae cells and Chl-a reached 97.9% and 96.7%, respectively. 2 O 4 :CaCl 2 When (w:w)=1:1, the removal rates of algae cells and Chl-a reached 98.9% and 97.0%, respectively. 2 O 4 :CaCl 2 With the increase of the (w:w) substance ratio, the removal effect of algae cells and Chl-a did not improve significantly. Under the conditions of the three substance ratios, the removal rates were basically the same.

[0060] from Figure 5 (b) It can be seen that without CaC 2 O 4The turbidity of the algae stock solution after crystallization algae removal is 51.4NTU. 2 O 4 The turbidity of the water body after crystallization algae removal is greatly reduced. 2 O 4 With CaCl 2 When the ratio of the added substances reached 0.25:1, 0.5:1, and 1:1, the turbidity of the water after algae removal dropped to 3.8, 8.4, and 17.3 NTU, respectively. 2 O 4 With CaCl 2 As the amount of substance increases, the turbidity of the water increases. Therefore, when ensuring CaC 2 O 4 While crystallization removes Microcystis aeruginosa, consider CaC 2 O 4 The effect of crystallization on water turbidity is that when CaCl 2 The addition concentration reaches 6mmol / L, NaC 2 O 4 :CaCl 2 When (w:w)=0.25:1, CaC 2 O 4 Crystallization has better algae removal effect.

[0061] Likewise, Figure 6 The medium target was Microcystis whitleyi, and H 2 O 2 During the pre-oxidation treatment (the pre-treatment scheme is: direct addition method, adding 0.5mL hydrogen peroxide / 200mL system, pre-treatment for 2-3h and standing), the "system" refers to the cultured Microcystis algae solution in Example 1. In the actual water treatment process, the "system" refers to the water body with Microcystis bloom. When NaC 2 O 4 With CaCl 2 When the ratio of the added substances reached 0.25:1, 0.5:1, and 1:1, respectively, the removal rates of algae cells reached 41.5%, 50.0%, and 70.2%, respectively, and the removal rates of Chl-a reached 34.6%, 51.3%, and 74.6%, respectively; 2 O 2 After pre-oxidation treatment, when NaC 2 O 4 With CaCl 2 When the ratio of the amount of added substances reached 0.25:1, 0.5:1, and 1:1, respectively, the removal rates of algae cells reached 64.0%, 70.5%, and 75.0%, respectively, and the removal rates of Chl-a reached 57.4%, 76.7%, and 86.3%, respectively. According to the experimental results, the use of H 2 O2 After pre-oxidation, the 2 O 2 The removal rates of algae cells and Chl-a after pre-oxidation were improved, and with the increase of NaC 2 O 4 :CaCl 2 As the amount of substance increases, the removal effect of algae cells and Chl-a is significantly improved. Figure 3-6 (b) It can be seen that after H 2 O 2 Pre-oxidized but without CaC 2 O 4 The turbidity of the algae stock solution after crystallization algae removal was 42.8 NTU, while the turbidity of the algae stock solution after CaC 2 O 4 The turbidity of the water body after crystallization algae removal is greatly reduced. 2 O 4 With CaCl 2 When the ratio of the added substances reached 0.25:1, 0.5:1, and 1:1, the turbidity of the water after algae removal was 18.7, 16.0, and 14.8 NTU, respectively. 2 O 4 With CaCl 2 As the amount of substance increases, the turbidity of the water decreases slightly. Therefore, when ensuring CaC 2 O 4 While crystallization removes Microcystis whitley, consider CaC 2 O 4 The effect of crystallization on water turbidity is that when CaCl 2 The addition concentration reaches 8mmol / L, NaC 2 O 4 :CaCl 2 When (w:w)=1:1, CaC 2 O 4 Crystallization has better algae removal effect.

[0062] Figure 7 The results showed that the removal effect of algal cells and chlorophyll was very limited when targeting Microcystis aquaticus. 2 O 4 When algae removal is performed by crystallization, the algae removal effect is significantly enhanced, such as Figure 7 As shown. Figure 7 (a) It can be seen that when NaC 2 O 4 With CaCl 2When the ratio of the added substances reached 0.25:1, 0.5:1, and 1:1 respectively, the removal rate of algae cells could reach more than 70%, and the removal rate of Chl-a could reach more than 80%. 2 O 4 :CaCl 2 When (w:w)=0.25:1, the removal rates of algae cells and Chl-a reached 72.7% and 80.8% respectively; 2 O 4 :CaCl 2 When (w:w)=0.5:1, the removal rates of algae cells and Chl-a reached 84.5% and 88.9% respectively; 2 O 4 :CaCl 2 When (w:w)=1:1, the removal rates of algae cells and Chl-a reached 74.7% and 83.0%, respectively. 2 O 4 With CaCl 2 As the amount ratio of substances increases, the removal effect of algae cells and Chl-a increases first and then decreases. Figure 7 (b) It can be seen that without CaC 2 O 4 The turbidity of the algae stock solution after crystallization algae removal is 55.5NTU. 2 O 4 The turbidity of the water body after crystallization algae removal is greatly reduced. 2 O 4 With CaCl 2 When the ratio of the added substances reached 0.25:1, 0.5:1, and 1:1, the turbidity of the water after algae removal was 25.3, 12.7, and 25.5 NTU, respectively. 2 O 4 With CaCl 2 As the amount of substance increases, the turbidity of the water body decreases first and then increases. 2 O 4 While crystallization is effective in removing Microcystis blooms, CaC 2 O 4 The effect of crystallization on water turbidity is that when Ca 2+ The addition concentration reaches 8mmol / L, NaC 2 O 4 :CaCl 2 When (w:w)=0.5:1, CaC 2 O 4 Crystallization has better algae removal effect.

[0063] from Figure 8It can be seen from the curve in the figure that adding CaC 2 O 4 Crystallization to remove Microcystis will reduce the pH of the water, and as NaC 2 O 4 :CaCl 2 The increase of the amount ratio of (w:w) substance, the lower the pH value of water body is, the higher the pH value of water body is. 2 O 4 The degree of pH reduction of the three types of Microcystis water bodies by crystallization is Microcystis whitley> Microcystis aeruginosa> Microcystis aquae. 2 O 4 :CaCl 2 The ratio of the amount of substance (w:w) is 0.25:1 for Microcystis aeruginosa, 1:1 for Microcystis whitleyi, and 0.5:1 for Microcystis aquatica. The pH value of the water body decreases to 0.50, 0.32, and 0.12, respectively. Therefore, the addition of CaC 2 O 4 Crystallization removal of Microcystis has little effect on the pH value of water.

[0064] 1.2.3 Investigation of sediment characteristics

[0065] (1) XRD analysis

[0066] XRD measurement is a research method to determine the material composition, molecular structure and morphology, and crystal structure of the material by performing X-ray diffraction on the sample and analyzing its diffraction pattern. 2 O 4 Crystallinity analysis: Relative crystallinity calculation formula: ε=I c / (I c +I a )×100%(Where: I c is the integrated intensity of the crystallization peak in the XRD pattern, I a is the integrated intensity of the amorphous peak in the XRD pattern).

[0067] Table 1 CaC 2 O 4 Analysis of relative crystallinity of crystals

[0068]

[0069]

[0070] Through CaC 2 O 4 The XRD analysis of the crystalline pure material detected the presence of crystal peaks at the interplanar spacings d = 0.591, 0.364, 0.296, 0.235 and 0.197 nm, which were respectively attributed to the corresponding peaks of calcium oxalate monohydrate (COM). (020) (130) and Crystalline surface, such as Fig. 9 As shown, the results show that COM is generated. And compared Fig. 9 The three figures in the figure show that Fig. 9 The peak value of the crystallization peak of the pure substance in (b) is the highest. Fig. 9 The peak value of the crystallization peak of the pure substance in (c) is second, Fig. 9 The peak value of the crystallization peak of the pure substance in (a) is the lowest. The results show that as NaC 2 O 4 With CaCl 2 The increase in the amount of substance, CaC 2 O 4 The crystallization peak value of the crystal increases accordingly. And according to the relative crystallinity ε calculation formula, combined with the XRD pattern, CaC 2 O 4 The relative crystallinity ε of the pure crystalline substance is shown in Table 1. The results show that when NaC 2 O 4 With CaCl 2 When the ratio of the added substances reached 0.25:1, 0.5:1, and 1:1 respectively, CaC 2 O 4 The relative crystallinity ε of the crystals are 91.88%, 93.80%, and 96.99% respectively. 2 O 4 With CaCl 2 The increase in the amount of substance, CaC 2 O 4 The relative crystallinity ε of the crystalline pure substance increases accordingly. 2 O 4 After the crystal algae removal test, CaC 2 O 4 The peak value of the crystallization peak and the relative crystallinity ε of the crystals are reduced, such as Fig. 9 As shown in Table 1, the results show that when using CaC 2 O 4 During the crystallization algae removal process, algae cells 2 O 4 Inhibits the crystallization process and reduces CaC 2 O 4 The relative crystallinity ε of the crystal.

[0071] (2) IR analysis

[0072] IR measurement is to analyze the functional groups carried in the object to be tested. By comparing the characteristic wavenumbers of the chemical bonds of the sample with those in the standard spectrum, the chemical bond type is analyzed and the type of compound is identified. The sample to be tested is rolled into a transparent sheet and infrared measurement is performed by an infrared spectrometer (Vertex 70).

[0073] Fig.10 It can be seen that by CaC 2 O 4 The crystalline pure substance was subjected to IR detection and analysis, and it was detected that when NaC 2 O 4 With CaCl 2 When the ratio of the added substances reached 0.25:1, the infrared absorption peak was mainly concentrated at a wavelength of 3464cm -1 1320~1650cm -1 、510~920cm -1 Nearby; when NaC 2 O 4 With CaCl 2 When the ratio of the added substances reaches 0.5:1, 3060~3440cm -1 1310~1620cm -1 、510~960cm -1 Nearby; when NaC 2 O 4 With CaCl 2 When the ratio of the added substances reaches 1:1, 3060~3490cm -1 1310~1620cm -1 、510~960cm -1 Nearby; through CaC 2 O 4 After the crystallization experiment, the material was subjected to IR detection and analysis, and it was detected that when NaC 2 O 4 :CaCl 2 When the ratio of the added substances reached 0.25:1, the infrared absorption peak was mainly concentrated at a wavelength of 3431 cm -1 1060~1650cm -1 、510~920cm -1 Nearby; when NaC 2 O 4 With CaCl 2 When the ratio of the added substances reaches 0.5:1, 3060~3440cm -1 1320~1620cm -1 、510~890cm -1 Nearby; when NaC 2 O4 With CaCl 2 When the ratio of the added substances reaches 1:1, 3060~3440cm -1 1320~1620cm -1 、510~950cm -1 Nearby. Contrast Fig.10 CaC 2 O 4 The absorption peak of the crystalline pure substance, Fig.10 The absorption peak ratio of pure substance in (a-1) Fig.10 (b-1) and Fig.10 The absorption peaks of the pure substance in (c-1) are reduced by two, at 3060 cm -1 and 3440cm -1 The results show that with the increase of NaC 2 O 4 With CaCl 2 The different ratios of the amount of substances will cause CaC 2 O 4 The change of the absorption peak position of the crystal. Fig.10 CaC 2 O 4 Absorption peaks of pure crystalline substance and experimental substance, peak values ​​of the experimental substance at each absorption peak position and CaC 2 O 4 The peak values ​​of the pure crystalline substance are basically the same. The results show that when using CaC 2 O 4 During the crystallization algae removal process, the algae cells basically did not change CaC 2 O 4 The composition of functional groups and chemical bond activity inside the crystal.

[0074] Example 2

[0075] Since DOM in the environment is an external factor that affects the treatment of Microcystis blooms, it will have a certain impact on the treatment effect of Microcystis blooms. DOM will compete with negatively charged algal cells for cationic flocculants, hindering the flocculation process and reducing the removal effect; react with oxidants, reducing the oxidative effect of oxidants and reducing the removal effect; it can participate in the process of photosensitization conversion as a special light-induced factor, and participate in the indirect photodegradation process of algae toxins, which has a positive effect on the degradation of algae toxins.

[0076] In this example, three different types of DOM (humic acid, glucose, amino acids) and their mixtures were added to the algae solution to study the effect of CaC 2 O 4The effect of crystallization system on the removal efficiency of three types of Microcystis was investigated by changing the type and concentration of DOM in the reaction system. 2 O 4 Effect of crystallization on algae cell removal efficiency in algae-containing water, CaC 2 O 4 The algaecide efficiency of crystallization was evaluated.

[0077] 2.1 Effect of single component DOM on CaC 2 O 4 Study on the effect of crystallization on algae removal efficiency

[0078] To investigate the effects of different concentrations of humic acid, glucose, tryptophan and tyrosine on CaC 2 O 4 The effect of crystallization on the removal of Microcystis aeruginosa, Microcystis whitleyi and Microcystis aquaeum. The concentration gradient of humic acid and glucose was set to 0, 2, 4, 6, 8, 10 mg / L, and the concentration gradient of tryptophan and tyrosine was set to 0, 0.4, 0.8, 1.2, 1.6, 2 mg / L. After standing for 6 hours, the water sample 3 cm below the liquid surface was taken for absorbance at 680 nm (A 680 ) detection, chlorophyll (Chl-a) concentration determination and pH value determination. The experimental results are shown in Fig.11 , Fig.12 , Fig.13 , Fig.14 .

[0079] Depend on Fig.11 It can be seen that adding different types of DOM (humic acid, glucose, tryptophan, tyrosine) alone has a significant effect on CaC 2 O 4 Crystallization has an inhibitory effect on the removal of Microcystis aeruginosa, and as the DOM concentration increases, the inhibitory effect becomes greater. When the dosage of humic acid reaches 10 mg / L, the removal rate of algal cells reaches more than 62%, the removal rate of Chl-a reaches more than 69%, and the inhibitory effects of humic acid are 32% and 25% respectively; when the dosage of glucose reaches 10 mg / L, the removal rate of algal cells reaches more than 91%, the removal rate of Chl-a reaches more than 92%, and the inhibitory effects of glucose are 4% and 4% respectively; when the dosage of tryptophan reaches 2 mg / L, the removal rate of algal cells reaches more than 93%, the removal rate of Chl-a reaches more than 94%, and the inhibitory effects of tryptophan are 2% and 1% respectively; when the dosage of tyrosine reaches 2 mg / L, the removal rate of algal cells reaches more than 82%, the removal rate of Chl-a reaches more than 84%, and the inhibitory effects of tyrosine are 11% and 9% respectively. Analyzing the above experimental results, the factors affecting CaC in water bodies 2 O 4The main DOM components of crystallization removal of Microcystis aeruginosa were humic acid and some types of amino acids, which showed an inhibitory effect, while the remaining components had an inhibitory effect on CaC 2 O 4 Crystallization had little effect on removing Microcystis aeruginosa.

[0080] Depend on Fig.12 It can be seen that adding different types of DOM (humic acid HA, tryptophan Trp, tyrosine Tyr) alone has a significant effect on CaC 2 O 4 Crystallization can remove the inhibitory effect of Microcystis whitley, and as the DOM concentration increases, the inhibitory effect becomes greater. The inhibitory effect is: humic acid > tryptophan > tyrosine. Adding glucose alone has an inhibitory effect on CaC 2 O 4 Crystallization promotes the removal of Microcystis whitleyii, and the greater the DOM concentration, the greater the promotion effect. When the dosage of humic acid reaches 10 mg / L, the removal rate of algae cells reaches more than 56%, the removal rate of Chl-a reaches more than 72%, and the inhibitory effect of humic acid is 25% and 13% respectively; when the dosage of glucose reaches 10 mg / L, the removal rate of algae cells reaches more than 91%, the removal rate of Chl-a reaches more than 92%, and the promotion effect of glucose is 2% and 1.5% respectively; when the dosage of tryptophan reaches 2 mg / L, the removal rate of algae cells reaches more than 68%, the removal rate of Chl-a reaches more than 83%, and the inhibitory effect of tryptophan is 11% and 6.5% respectively; when the dosage of tyrosine reaches 2 mg / L, the removal rate of algae cells reaches more than 71%, the removal rate of Chl-a reaches more than 83%, and the inhibitory effect of tyrosine is 9% and 7% respectively. After analyzing the above experimental results, it is believed that the influence of CaC in water 2 O 4 The main DOM components of Microcystis whitleyi removed by crystallization were humic acid and amino acids, which showed an inhibitory effect. Glucose (Glu) had an inhibitory effect on CaC 2 O 4 Crystallization had little effect on removing Microcystis whitley.

[0081] Depend on Fig.13 It can be seen that the addition of humic acid alone has an effect on CaC 2 O 4 Crystallization can remove the inhibitory effect of Microcystis blooms, and the inhibitory effect is greater with the increase of DOM concentration. The effect of adding different types of DOM (glucose, tryptophan, tyrosine) on CaC 2 O 4Crystallization promotes the removal of water bloom Microcystis, and as the DOM concentration increases, the promotion effect is greater, and the promotion effect is: glucose>tryptophan>tyrosine. When the dosage of humic acid reaches 10mg / L, the removal rate of algae cells reaches more than 65%, the removal rate of Chl-a reaches more than 76%, and the inhibitory effect of humic acid is 6% and 5% respectively; when the dosage of glucose reaches 10mg / L, the removal rate of algae cells reaches more than 89%, the removal rate of Chl-a reaches more than 92%, and the promotion effect of glucose is 8% and 11% respectively; when the dosage of tryptophan reaches 2mg / L, the removal rate of algae cells reaches more than 84%, the removal rate of Chl-a reaches more than 86%, and the promotion effect of tryptophan is 5.5% and 4.5% respectively; when the dosage of tyrosine reaches 2mg / L, the removal rate of algae cells reaches more than 84%, the removal rate of Chl-a reaches more than 85%, and the promotion effect of tyrosine is 5.5% and 4% respectively. After analyzing the above experimental results, it is believed that the influence of CaC in water 2 O 4 The main DOM components of crystallization removal of Microcystis algae are humic acid and glucose. Humic acid has an inhibitory effect, glucose has a promoting effect, and amino acids have a positive effect on CaC 2 O 4 Crystallization has little effect on removing Microcystis blooms.

[0082] like Fig.14 As shown in the figure, it can be seen from the curve that the addition of humic acid has an effect on CaC 2 O 4 Crystallization to remove Microcystis will reduce the pH value of the water body. The reduction degrees for Microcystis aeruginosa, Microcystis whitley and Microcystis aquae are 0.1, 0.4 and 0.3 respectively. Adding glucose has a significant effect on CaC 2 O 4 Crystallization of Microcystis had little effect on the pH value of the water body; the addition of tryptophan and tyrosine had little effect on CaC 2 O 4 Crystallization to remove Microcystis will increase the pH value of water, and the increase for Microcystis aeruginosa, Microcystis whitley, and Microcystis aquae is 0.3 and 0.2, respectively. Humic acid, glucose, tryptophan, and tyrosine have an impact on CaC 2 O 4 The influence of water pH on crystallization removal of Microcystis is in the following order: humic acid > tryptophan > tyrosine > glucose.

[0083] 2.2 Effects of multi-component DOM on CaC 2 O 4 Study on the effect of crystallization on algae removal efficiency

[0084] The effects of mixed DOM on CaC 2 O 4The effect of crystallization on the removal of Microcystis aeruginosa, Microcystis whitley and Microcystis aquaeum was shown in Table 2. The amount of humic acid, glucose, tryptophan and tyrosine was set aside for 6 hours. After the precipitation, the water sample at 3 cm below the liquid surface was taken for absorbance at 680 nm (A 680 ) detection and chlorophyll (Chl-a) concentration determination, the experimental results are shown in Fig.15 , 16 、17.

[0085] Depend on Fig.15 It can be seen that the CaC 2 O 4 The removal rates of Microcystis aeruginosa cells and chlorophyll by crystallization were lower than those of the blank control group. The removal rates of CaC 2 O 4 The inhibitory effect of crystallization on the removal of Microcystis aeruginosa was the most obvious, indicating that HA is an inhibitory factor for CaC 2 O 4 Crystallization is the key DOM substance in the removal of Microcystis aeruginosa.

[0086] Depend on Fig.16 It can be seen that the CaC 2 O 4 The removal rates of Microcystis whitleyi cells and chlorophyll by crystallization were lower than those of the blank control group. The removal rates of CaC 2 O 4 The inhibitory effect of crystallization on the removal of Microcystis whitley was the most obvious, indicating that HA is the inhibitory factor of CaC 2 O 4 Crystallization is the key DOM substance for the removal of Microcystis whitley, but a certain concentration of Glu will weaken the effect of other types of DOM on CaC 2 O 4 Crystallization removes the inhibitory effect of Microcystis whitley.

[0087] Depend on Fig.17 It can be seen that the CaC 2 O 4 The removal rate of Microcystis aquatica cells and chlorophyll by crystallization was basically the same as that of the blank control group, indicating that Glu, Trp, and Tyr have a significant effect on CaC 2 O 4 The promoting effect of crystallization in removing Microcystis blooms basically offset the inhibitory effect of HA.

[0088] 2.2.1 Orthogonal experimental study

[0089] The effects of different concentrations of mixed DOM on CaC 2 O 4In order to study the effect of crystallization on the removal efficiency of Microcystis aeruginosa, Microcystis whitley and Microcystis aquae, a three-factor three-level orthogonal experiment was designed. The dosages of humic acid, glucose, tryptophan and tyrosine are shown in Table 2. The mixture was allowed to settle for 6 hours. After the sedimentation, water samples were taken 3 cm below the liquid surface for absorbance detection at 680 nm (A680). The experimental results are shown in Tables 2-4, respectively. The results were analyzed and compared by calculating the range.

[0090] Table 2 Results of three-factor three-level orthogonal experiment (Microcystis aeruginosa)

[0091]

[0092] Through the above orthogonal experiment, it can be seen that the range of HA is the largest at 0.082, followed by Trp+Tyr with a range of 0.044, and finally Glu with a range of 0.033. According to the size of the range R, different types of DOM affect CaC 2 O 4 The order of crystallization removal of Microcystis aeruginosa is HA concentration > Trp + Tyr concentration > Glu concentration. It can also be determined that the influence of CaC 2 O 4 The most unfavorable conditions for crystallization removal of Microcystis aeruginosa are HA concentration of 8 mg / L, Glu concentration of 8 mg / L, Trp+Tyr concentration of 4 mg / L, and the removal efficiency of Microcystis aeruginosa cells is 74.65%.

[0093] Table 3 Results of three-factor three-level orthogonal experiment (Microcystis whitleyi)

[0094]

[0095] Through the above orthogonal experiment, it can be seen that the range of HA is the largest at 0.033, followed by Glu with a range of 0.028, and finally Trp+Tyr with a range of 0.023. According to the size of the range R, different types of DOM affect CaC 2 O 4 The order of crystallization removal of Microcystis whitleyi is HA concentration > Glu concentration > Trp + Tyr concentration. It can also be determined that the influence of CaC 2 O 4 The most unfavorable conditions for crystallization removal of Microcystis whitleye were HA concentration of 4 mg / L, Glu concentration of 4 mg / L, and Trp+Tyr concentration of 4 mg / L, and the removal efficiency of Microcystis whitleye cells was 71.97%.

[0096] Table 4 Results of three-factor three-level orthogonal experiment (Microcystis flos-aquae)

[0097]

[0098] Through the above orthogonal experiment, it can be seen that the range of HA is the largest at 0.021, followed by Trp+Tyr with a range of 0.017, and finally Glu with a range of 0.003. According to the size of the range R, different types of DOM affect CaC 2 O 4 The order of crystallization to remove Microcystis blooms is HA concentration > Trp+Tyr concentration > Glu concentration. It can also be determined that the influence of CaC 2 O 4 The most unfavorable conditions for crystallization removal of Microcystis aquae are HA concentration of 8 mg / L, Glu concentration of 8 mg / L, Trp+Tyr concentration of 4 mg / L, and the removal efficiency of Microcystis aquae cells is 86.19%.

[0099] 2.3 CaC within 30 days 2 O 4 Effect of crystallization duration on the removal efficiency of Microcystis

[0100] Investigate CaC within 30 days 2 O 4 The crystallization was continued to remove Microcystis aeruginosa, Microcystis whitley and Microcystis aquae. The dosage of DOM is shown in Table 7. NaC 2 O 4 :CaCl 2 (w:w) = 0.5:1; let it settle for 30 days, and take water samples 3 cm below the liquid surface every 5 days during the experiment, and measure the absorbance at 680 nm (A 680 ) detection, the experimental results are as follows Fig.18 To avoid the accidental nature of the experimental results, each group of experiments was performed 3 times and the final results were averaged.

[0101] Table 5 Three-factor three-level orthogonal test

[0102]

[0103] After 30 days of continuous measurement of the absorbance of the supernatant, the effect of DOM on CaC 2 O 4 Crystallization did not have much effect on the removal efficiency of Microcystis. The overall removal rate of Microcystis aeruginosa was finally maintained at more than 95%. However, with the passage of time, the removal rate of Microcystis aeruginosa cells showed a downward trend, with Glu being the most obvious. The overall removal rate of Microcystis whitley was finally maintained at more than 99%. With the passage of time, the removal rate of Microcystis whitley cells showed an upward trend, which may be due to the fact that H 2 O 2 Has a sustained algaecidal effect and stabilizes CaC 2 O 4Removal effect of crystallized Microcystis cells; in the first 25 days, the overall removal rate of Microcystis blooms showed a slight downward trend with the passage of time, but in the next 5 days, the removal rate of Microcystis blooms cells increased instead, and the overall removal rate was finally maintained at more than 96%.

[0104] 2.4 Study on sediment characteristics

[0105] When sampling, BG-11 culture medium was added to the water of Qingshan Lake after filtering through a 0.45 μm filter membrane to dilute the algae cell stock solution for algae cultivation, and later for CaC 2 O 4 Crystallization algae removal experiment. Ca 2+ With C 2 O 4 2- The dosage reached the most suitable algae removal concentration for Microcystis aeruginosa, Microcystis whitleyi, and Microcystis aquae. The experimental period was 2 days. During the experiment, the sedimentation experimental phenomenon of algae cells was recorded. After the experiment, water samples were taken 3 cm below the liquid surface for absorbance at 680 nm (A 680 ) detection, chlorophyll (Chl-a) concentration determination and turbidity determination, and XRD analysis of the sediment after precipitation and CaC 2 O 4 Analysis of the three-dimensional fluorescence characteristic changes and three-dimensional fluorescence spectrum index of natural water DOM during the crystallization algae removal process. To avoid the accidental nature of the experimental results, each group of experiments was performed three times and the final results were averaged.

[0106] (1) XRD analysis

[0107] Table 6 CaC 2 O 4 Relative crystallinity analysis of crystalline deposits

[0108]

[0109] Through CaC 2 O 4 The crystalline deposits were subjected to XRD analysis, such as Fig.19 As shown, the results showed that HA, Glu, Trp, Tyr compared with the control group, CaC 2 O 4 The crystal form of the crystals did not change significantly, and CaC 2 O 4 There is no obvious shift in the position of the crystallization peak of the crystals, but HA will cause CaC 2 O 4 The peak height of the crystallization peak decreases, and Glu does not change CaC 2 O 4The peak height of the crystallization peak, Trp and Tyr will lead to CaC 2 O 4 The peak height of the crystallization peak increases. According to the relative crystallinity ε calculation formula, combined with the XRD pattern, CaC 2 O 4 The relative crystallinity ε of the crystalline sediments is shown in Table 6. The results show that in CaC 2 O 4 During the crystallization algae removal process, HA will reduce CaC 2 O 4 The relative crystallinity ε of the crystal inhibits CaC 2 O 4 Crystal nucleation; Glu on CaC 2 O 4 The relative crystallinity ε of the crystal has little effect; Trp and Tyr will increase CaC 2 O 4 The relative crystallinity ε of the crystal promotes CaC 2 O 4 Crystal nucleation, HA, Glu, Trp, Tyr to CaC 2 O 4 The effect of crystal nucleation is Trp>Tyr>Glu>HA.

[0110] (2) IR analysis

[0111] After adding DOM components, CaC 2 O 4 The sediment after crystallization and algae removal was subjected to IR detection and analysis, and compared Fig.10 Medium CaC 2 O 4 IR graph of the crystal experimental group, CaC was detected 2 O 4 The infrared absorption peak of the crystal is still mainly concentrated in the wavelength range of 3060-3490 cm -1 1310~1620cm -1 、510~960cm -1 Nearby, and CaC after adding DOM components 2 O 4 The peak values ​​of the sediment after crystallization and algae removal at each absorption peak position and CaC 2 O 4 The peak values ​​of the crystallization experimental group were basically the same. The results showed that after adding DOM components, CaC 2 O 4 During the crystallization algae removal process, the DOM components basically did not change CaC 2 O 4 The composition of functional groups and chemical bond activity inside the crystal.

[0112] As can be seen from Example 1, when CaCl 2 Solution and Na 2 C 2 O 4 When the solutions are used together, the CaC 2 O 4 The removal effect of crystals on algae is far better than that of Ca 2+ The result of a single action; and when C 2 O 4 2- With Ca 2+ The molar ratio of Ca is 0.25-1:1. 2+ The input concentration is 6-8mM, which has a better effect on removing algae.

[0113] It can be seen from Example 2 that even when the DOM in the water changes, the method of the present invention will not be affected by external factors. After the water is treated by the method of the present invention for 30 days, the overall removal rate of Microcystis can finally be maintained at more than 96%.

Claims

1. Ca 2+ With C2O4 2- The formed crystal system is applied in removing Microcystis from water bodies.

2. The use according to claim 1, characterized in that The microcystis is any one of Microcystis aeruginosa, Microcystis whitleyi and Microcystis flos-aquae.

3. The use according to claim 1, characterized in that Contains Ca 2+ and C2O4 2- Salts of these two crystal-forming ions are added to a body of water containing Microcystis.

4. The use according to claim 3, characterized in that Ca 2+ and C2O4 2- Finally, add glucose or substances containing glucose into the water.

5. The use according to claim 3, characterized in that Contains Ca 2+ The salt is CaCl2, containing C2O4 2- The salt is NaC2O4; C2O4 2- With Ca 2+ The molar ratio is: 0.25~1:1, Ca 2+ The input concentration is 6~8mM.

6. A calcium salt-based microcystis algaecide tolerant to DOM, characterized in that: The algaecide contains Ca 2+ and C2O4 2- Salts of these two crystal-forming ions.

7. The algaecide according to claim 6, characterized in that The algaecide contains CaC2O4 crystals.

8. The method for removing Microcystis using the algaecide according to claim 6, comprising the following steps: (1) Prepare CaCl2 solution and Na2C2O4 solution; (2) Pour the prepared CaCl2 solution and Na2C2O4 solution into the water containing Microcystis, let it stand and settle; 2+ The concentration of C2O4 was maintained at 6~8mM. 2- With the Ca in the CaCl2 solution in (1) 2+ The molar ratio is: 0.25~1:

1.

9. The method for removing Microcystis according to claim 8, characterized in that: In (2), before adding the CaCl2 solution and the Na2C2O4 solution, hydrogen peroxide is added to the water body by direct addition at a ratio of 0.5 mL hydrogen peroxide / 200 mL water body, and the mixture is allowed to stand for 2 to 3 h. Then, the CaCl2 solution and the Na2C2O4 solution are added to the water body.

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