A method for inhibiting the growth of target algae by adding suspended particles

Abstract

The present invention provides a method for inhibiting the growth of target algae by adding suspended particles. The present invention determines the expected concentration of suspended particles in a water body by using the obtained growth inhibition parameters of the target algae, the particle size of the particles to be added, and the OM value, and based on this, adds particles of a specific particle size and OM value to the water body, thereby achieving the purpose of inhibiting the growth of the target algae. The method comprises the following steps: 1) determining the target algae that need to be inhibited in the water body; 2) determining the growth inhibition parameters for inhibiting the growth of the target algae; 3) determining the particle size parameters and OM value of the particles to be added, and determining the expected suspended particle concentration conditions of the water body according to the growth inhibition parameters, the particle size parameters, and the OM value; 4) adding the particles to the water body according to the expected suspended particle concentration conditions of the water body to inhibit the growth of the target algae.

Description

Technical Field

[0001] The present invention relates to the technical field of water environment restoration and water quality risk prevention and control, and in particular to a method for inhibiting the growth of target algae by adding suspended particles. Background Art

[0002] Eutrophication and harmful algal blooms have become the main water quality problems in most freshwater and coastal marine ecosystems in the world. In recent decades, under the influence of global changes and human activities, the input of large amounts of nitrogen and phosphorus nutrient pollution loads has led to increasing eutrophication of rivers, lakes and reservoirs, and even algal blooms. The massive reproduction of algae not only leads to water quality deterioration and death of aquatic organisms, but is often accompanied by secondary risk pollutants such as odor and algal toxins, which not only endanger the health of natural water environment, but also seriously affect urban water supply and drinking water safety. In response to the risk of algae pollution, existing prevention and control measures include chemical, physical and biological methods. As far as chemical methods are concerned, harmful algae are often controlled by metals, photosensitizers, algaecides and other chemicals. Although chemical and physical methods can effectively and quickly remove harmful algae, they have not been widely used due to their high cost, serious secondary pollution and negative impact on humans and other aquatic organisms, and are especially not suitable for application in natural water bodies. Biological algae control is mainly based on aquatic plants, aquatic animals and algaecidal microorganisms, using allelopathic effects, niche competition, predator-prey relationships, etc. to limit the excessive growth of algae.

[0003] As we all know, light conditions are one of the important environmental factors that affect algae growth. Studies have found that different algae species have significant differences in their adaptability to underwater light. In natural water bodies with sufficient nutrients, underwater light conditions are the key environmental factors that affect algae biology and growth rate in addition to temperature. By changing underwater light conditions, it is possible to regulate specific algae communities and even inhibit the growth and outbreak of harmful algae.

[0004] In the prior art, there have been some reports of cases of controlling underwater light by water surface shading (such as buoys, shading boards and sunshade nets, etc.). For example, patent application CN202021954278.X discloses a shading suppression device, patent application CN201120569468.4 discloses a mobile water surface shading and algae control device, and patent application CN202010270886.7 discloses a method for controlling green algae in seawater ponds based on a physical shading layer; however, the cost and engineering effect are not ideal. Summary of the invention

[0005] In view of this, the present invention provides a method for inhibiting the growth of target algae by adding particulate matter. The present invention determines the expected suspended particulate matter concentration in the water body through the obtained growth inhibition parameters of the target algae and according to the particle size and OM value of the particulate matter to be added, and adds particulate matter of a specific particle size and OM value into the water body according to the determined suspended particulate matter concentration, thereby achieving the purpose of inhibiting the growth of the target algae. The method based on the present invention is conducive to simple and economical algal bloom prevention and control and water quality regulation.

[0006] To achieve the purpose, the present invention provides the following technical solutions:

[0007] The present invention provides a method for inhibiting the growth of target algae by adding suspended particles, comprising the following steps:

[0008] 1) Identify the target algae in the water body whose growth needs to be inhibited;

[0009] 2) determining a growth inhibition parameter for inhibiting the growth of the target algae, wherein the growth inhibition parameter comprises at least one of turbidity, irradiance, and transparency of the water body;

[0010] 3) determining the particle size parameter and OM value of the particles to be added, and determining the expected suspended particle concentration condition of the water body according to the growth inhibition parameter, the particle size parameter and the OM value;

[0011] 4) Adding the particulate matter into the water body according to the expected suspended particulate matter concentration condition of the water body to inhibit the growth of the target algae.

[0012] In some embodiments, in step 3), the growth inhibition parameter, the particle size parameter and the OM value are substituted into a pre-established relationship model for calculation to determine the expected suspended particulate matter concentration condition of the water body.

[0013] In some embodiments, the relationship model includes a relationship (I), wherein the relationship (I) is a relationship between the turbidity of the water body and the concentration of suspended particles in the water body, the particle size parameter of the suspended particles, and the OM value of the suspended particles;

[0014] Preferably, the relationship (I) is established in the following manner:

[0015] Obtain multiple water samples, obtain the turbidity, suspended particle concentration and particle size parameter of each water sample, obtain the OM value of the suspended particles in each of the water samples, and obtain the relationship (I) between the turbidity and the suspended particle concentration, the particle size parameter of the suspended particles and the OM value of the suspended particles by fitting:

[0016] TUR=α1SPM+α2Dx+α3OM2(I);

[0017] Wherein, TUR is the turbidity of the water body, in NTU; SPM is the suspended particle concentration of the water body, in mg / L; OM2=exp(-OM); Dx is the particle size parameter of the suspended particles, in μm; α1, α2, α3 are the coefficients in the relation (I);

[0018] Preferably, the particle size parameter is D10, D50, D60 or D90.

[0019] In some embodiments, the growth inhibition parameter is the turbidity of the water body. In the step 3), the turbidity of the water body as the growth inhibition parameter and the particle size parameter and OM value of the particulate matter to be added are substituted into the relationship (I) to calculate the suspended particulate matter concentration, thereby determining the expected suspended particulate matter concentration condition of the water body.

[0020] In some embodiments, the relationship model further includes relationship formula (II) and relationship formula (III);

[0021] Wherein, the relational expression (II) is the relational expression between irradiance and underwater light attenuation coefficient, and the relational expression (II) is:

[0022]

[0023] Where K is the underwater light attenuation coefficient; z is the preset depth of the water body, in m; E(z) is the irradiance of the water body at the preset depth z, and E(0) is the irradiance of the water surface. The units of E(z) and E(0) are μmol / (m 2 .s);

[0024] The relation (III) is the relation between the underwater light attenuation coefficient and the turbidity of the water body;

[0025] Preferably, the relationship (III) is established in the following manner:

[0026] Water samples are obtained from multiple water bodies, E(0) and E(z) of each water body are obtained, and the underwater light attenuation coefficient of each water body is determined according to the relationship (II); the turbidity of each water sample is obtained, and the linear relationship between the underwater light attenuation coefficient and the turbidity of the water body is obtained by fitting according to the underwater light attenuation coefficient of each water body and the turbidity of each water sample:

[0027] K=a+b*TUR(III)

[0028] Wherein, TUR is the turbidity of the water body, and the unit is NTU; b is the slope of the relational formula (III), and a is the intercept of the relational formula (III).

[0029] In some embodiments, the growth inhibition parameter is irradiance, and the irradiance is used as the value of E(z) in relational formula (II) to obtain the irradiance E(0) of the water surface of the water body, and the preset depth z, E(z), and E(0) are substituted into relational formula (II) to obtain the underwater light attenuation coefficient of the water body;

[0030] Substituting the underwater light attenuation coefficient K into the relational formula (III) to calculate the turbidity of the water body;

[0031] The calculated turbidity of the water body and the particle size parameters and OM value of the particles to be added are substituted into the relationship (I) to calculate the suspended particle concentration, thereby determining the expected suspended particle concentration conditions of the water body.

[0032] In some embodiments, the relationship model further includes a relationship (IV), wherein the relationship (IV) is a relationship between the turbidity of the water body and the transparency of the water body;

[0033] Preferably, the relationship (IV) is established in the following manner:

[0034] The turbidity and transparency of each water sample are obtained, and the values ​​of the turbidity and the transparency are respectively transformed into lg logarithms and then linearly fitted to obtain the relationship between the turbidity and transparency of the water body:

[0035] log(SDD)=a+b×log(TUR) (IV)

[0036] Wherein, SDD is the transparency of the water body, in cm; TUR is the turbidity of the water body, in NTU; b is the slope of the relationship (ⅠⅤ), and a is the intercept of the relationship (ⅠⅤ).

[0037] In some embodiments, the growth inhibition parameter is the transparency of the water body. In the step 3), the transparency of the water body as the growth inhibition parameter is substituted into the relational formula (IV) to calculate the turbidity of the water body.

[0038] The calculated turbidity of the water body and the particle size parameters and OM value of the particles to be added are substituted into the relationship (I) to calculate the suspended particle concentration, thereby determining the expected suspended particle concentration conditions of the water body.

[0039] In some embodiments, in step 4), after the particulate matter is added, the water body is continuously monitored, and when the water body fails to meet the requirements of the growth inhibition parameters, the particulate matter is added again; or, in step 4), after the particulate matter is added, the water body is continuously monitored, and when the water body fails to meet the requirements of the growth inhibition parameters, the particle size parameters and / or OM values ​​of the particulate matter to be added are adjusted, and the expected suspended particle concentration conditions of the water body are re-determined according to step 3); then, the particulate matter is added to the water body according to the re-determined expected suspended particle concentration conditions of the water body.

[0040] In some embodiments, in step 4), the particulate matter is added by dry method or wet method;

[0041] And / or, in step 4), the particulate matter to be added is selected from one or more of clay minerals, sludge from sedimentation tanks of water plants, activated sludge, bottom mud of natural water bodies and harmless industrial waste particulate matter.

[0042] The present invention also provides an application of the method described above, wherein the method is applied in algal bloom prevention and control or water quality regulation.

[0043] The technical solution provided by the present invention has the following beneficial effects:

[0044] The present invention achieves the regulation of algae growth by adding particulate matter into the water body, which can effectively achieve the control and prevention of algae-derived water pollution including algal blooms, odors, etc. The method provided by the present invention has the characteristics of simple and convenient operation, low cost and ecological safety. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the relationship between suspended particle concentration, median particle size and turbidity.

[0046] Figure 2 It is the fitting relationship between turbidity TUR and light attenuation coefficient K.

[0047] Figure 3 This is the fitting relationship between turbidity TUR and transparency SDD after logarithmic transformation.

[0048] Figure 4 Figure 2 shows the relationship between expected turbidity and actual turbidity and suspended particle concentration (left), and the relationship between turbidity and Cladophora biomass (right).

[0049] Figure 5 Cell density diagram of Microcystis aeruginosa in different E(z) experimental groups. DETAILED DESCRIPTION

[0050] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0051] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0052] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents or instruments used without specifying the manufacturer are all conventional products that can be purchased commercially.

[0053] The present invention provides a method for inhibiting the growth of target algae by adding suspended particles, which mainly comprises the following steps:

[0054] 1) Identify the target algae in the water body whose growth needs to be inhibited;

[0055] 2) determining a growth inhibition parameter for inhibiting the growth of the target algae, wherein the growth inhibition parameter comprises at least one of turbidity, irradiance, and transparency of the water body;

[0056] 3) determining the particle size parameters and OM value (i.e., the organic matter mass ratio of the particles) of the particles to be added to the water body where the target algae need to be inhibited (i.e., "particles to be added"), and determining the expected suspended particle concentration conditions of the water body according to the growth inhibition parameters and the particle size parameters and OM value of the particles to be added;

[0057] 4) Adding particulate matter (i.e., the particulate matter to be added having the above-mentioned particle size parameters and OM values) into the water body according to the expected suspended particulate matter concentration condition of the water body determined in step 3) to inhibit the growth of the target algae.

[0058] The target algae in step 1) are algae in the water body whose growth needs to be suppressed, such as algae species that bring algae-derived pollutants into the water body, etc. The target algae can be determined based on actual water environment problems.

[0059] In step 2), the determination of the growth inhibition parameters for inhibiting the growth of the target algae can be determined through existing literature records. For example, according to literature reports, the growth of a specific target algae will be inhibited under a certain transparency or turbidity of the water body. Then, based on the report in the literature, the transparency data or turbidity data of the water body is used as the growth inhibition parameter; or, for example, if the literature reports the optimal growth light intensity (i.e., optimal irradiance) of a specific target algae, the irradiance that can inhibit the growth of the target algae can be set based on the literature report, for example, lower than the above-mentioned optimal irradiance; if there is a research or data basis, the growth inhibition parameters of the target algae growth can also be determined by experiments, and are not limited to the reports in the literature. The specific method for determining the algae growth inhibition parameters is known or understood by those skilled in the art based on the existing experimental means, conventional technical knowledge and / or common knowledge.

[0060] In step 3) of the present invention, the expected suspended particulate matter concentration condition in the water body is determined by substituting the growth inhibition parameter, the particle size parameter and the OM value of the particulate matter to be added into a pre-established relationship model for calculation.

[0061] In some embodiments, the relationship model includes a relationship (I), which is a relationship between the turbidity of a water body and the concentration of suspended particles in the water body, and between the particle size parameters of the suspended particles and the OM value of the suspended particles.

[0062] Specifically, relation (I) is established in the following way:

[0063] Obtain multiple water samples, the number of which is not less than 500, for example. The water samples can be obtained in lakes, reservoirs, pits, ponds, streams, and rivers (covering common surface water types) under different scenarios (including sunny days, rainy days, and after rain). Obtain the turbidity, suspended particle concentration, suspended particle size distribution, and OM value of each water sample. The OM value can be determined by filtering, drying, and burning the suspended particles in each water sample. The relationship between turbidity and suspended particle concentration, particle size parameter, and OM value is obtained by fitting the turbidity, suspended particle concentration, suspended particle size parameter, and OM value of the above water samples (I):

[0064] TUR=α1SPM+α2Dx+α3OM2(I);

[0065] Wherein, TUR is the turbidity of the water body, in NTU; SPM is the suspended particle concentration of the water body, in mg / L; Dx is the particle size parameter of the suspended particles, in μm; OM2=exp(-OM); α1, α2, α3 are the coefficients in the relationship (I).

[0066] The particle size parameter Dx may be a parameter that can represent a characteristic particle size of the suspended particles, such as D10, D50, D60 or D90.

[0067] In some embodiments, the relationship model further includes relationship (II) and relationship (III); wherein, relationship (II) is the relationship between irradiance and underwater light attenuation coefficient, and relationship (II) is:

[0068]

[0069] Where K is the underwater light attenuation coefficient; z is the preset depth of the water body, in meters; E(z) is the irradiance of the water body at the preset depth z, and E(0) is the irradiance on the water surface. The units of E(z) and E(0) are μmol / (m 2 .s);

[0070] Equation (III) is the relationship between the underwater light attenuation coefficient and the turbidity of the water body.

[0071] Specifically, the relationship (III) is established in the following manner:

[0072] Water samples are obtained from multiple water bodies, the irradiance E(0) of the water surface of each water body and the irradiance E(z) of the water body at a preset depth z are obtained, and the underwater light attenuation coefficient of each water body related to the preset depth z is calculated and determined according to the above relationship (II); the turbidity of each water sample is obtained; the turbidity of each water sample obtained and the underwater light attenuation coefficient of each water body related to the preset depth z are fitted to obtain a linear relationship between the underwater light attenuation coefficient K and the turbidity TUR of the water body:

[0073] K=a+b*TUR(III)

[0074] Wherein, TUR is the turbidity of the water body, the unit is NTU; b is the slope of equation (III), and a is the intercept of equation (III).

[0075] In some implementations, the relationship model further includes a relationship equation (IV), which is a relationship equation between the turbidity of a water body and the transparency of the water body.

[0076] Specifically, relation (IV) is established as follows:

[0077] Water samples were obtained from multiple water bodies, and the turbidity and transparency of each water sample were obtained. The values ​​of turbidity and transparency were logarithmically transformed and then linearly fitted to obtain the relationship between the turbidity and transparency of the water body:

[0078] log(SDD)=a+b×log(TUR) (IV)

[0079] Wherein, SDD is the transparency of the water body, in cm; TUR is the turbidity of the water body, in NTU; b is the slope of the relationship (ⅠⅤ), and a is the intercept of the relationship (ⅠⅤ).

[0080] The establishment process of the above relationship model is exemplarily introduced as follows. The following is only the establishment process of the relationship model in a specific embodiment, which is intended to facilitate understanding of the establishment idea of ​​the relationship model of the present invention, but it should not be understood that the present invention is limited to this:

[0081] S1) Establish the relationship (I):

[0082] Obtain water samples, the number of which shall not be less than 500, and the water samples shall be obtained from lakes, reservoirs, pits, ponds, streams, and rivers (covering common surface water types) under different scenarios (including sunny days, rainy days, and after rain). The suspended particulate matter concentration (SPM) of each water sample was determined by the weight method (national standard: GB 11901-89). Specifically, 500 ml of water sample was filtered on a 0.45 μm CN-CA filter membrane of known constant weight, dried in an oven at 105°C for 1 hour after filtration, then cooled to room temperature in a dryer, and dried, cooled, and weighed repeatedly until the weight was constant, and then the SPM concentration was calculated based on the weight difference; then the filter membrane was placed in a muffle furnace and burned at 450°C for 4 hours to remove organic matter, and the organic matter ratio OM of the suspended particulate matter was calculated according to the formula OM = (BC) / (BA), where A is the weight of the filter membrane + weighing bottle, g; B is the weight of the suspended matter + filter membrane + weighing bottle, g; and C is the weight of the inorganic suspended matter + filter membrane + weighing bottle, g. The determination of the above SPM concentration and OM value is well known to those skilled in the art, and the parts not described in detail are all known or understood by those skilled in the art based on the conventional technical knowledge or common knowledge they have mastered.

[0083] In this example, the particle size parameter of suspended particulate matter is the particle size distribution, which is measured by a Malvern laser particle size analyzer (MASTERSIZER 3000E), with D50 as the particle size parameter of suspended particulate matter (D50 is the particle size corresponding to when the cumulative particle size distribution percentage reaches 50%); the turbidity TUR of the water body is measured in situ at the sampling site by a portable multi-parameter water quality analyzer (YSI Professional Plus).

[0084] TUR was fitted with SPM, D50 and OM data by multiple linear fitting, and the OM value was converted according to OM2 = exp(-OM). In the process of establishing the relationship (I), the insignificant intercept term was removed, and finally the following relationship (I) was obtained:

[0085] TUR=α1SPM+α2D50+α3OM2(I)

[0086] In this example, The R of the relation (I) 2 =0.87, and the p-values ​​corresponding to the parameter hypothesis tests are all less than 0.05.

[0087] Figure 1 The fitting relationship between turbidity, suspended particle concentration and D50 in the example is given for reference.

[0088] S2) Relation (II) and Relation (III)

[0089] Equation (II) is the relationship between irradiance and underwater light attenuation coefficient. The calculation formula of underwater light attenuation coefficient K is as follows:

[0090]

[0091] Where K is the underwater light attenuation coefficient, z is the preset depth of the water body, in meters; E(z) is the irradiance of the water body at the preset depth z, in μmol / (m 2 .s), E(0) is the irradiance on the water surface, in μmol / (m 2 .s). The irradiance is measured using an underwater full-spectrum photosynthetically active radiometer (MQ-510). The preset depth can be specifically determined based on the prevention and control needs of the target algae in the target water body in the actual application scenario.

[0092] The relationship (III) is established as follows:

[0093] A plurality of water samples are obtained from a plurality of water bodies, E(0) of each water body and E(z) at a preset depth z are measured, and the underwater light attenuation coefficient of each water body is calculated and determined according to the relation (II); the turbidity of each water sample is obtained; the underwater light attenuation coefficient of each water body and the turbidity of each water sample are fitted to obtain the relation (II), which is specifically: K = (2.39 ± 0.20) + (0.14 ± 0.013) × TUR, R 2 =0.62. For the fitting relationship diagram, see Figure 2 .

[0094] S3) Establish the relationship (IV)

[0095] By measuring the turbidity TUR and the corresponding transparency SDD of each water sample (the transparency SDD is measured by the Secchi transparency disk), a series of turbidity and transparency data are obtained. The turbidity and transparency data are both lg-converted. The converted SDD and TUR have a good univariate linear relationship (see Figure 3 ), and the linear fitting gives the relation (IV). In this example, the relation (IV) is TUR=10 (2.48243-lg(SDD)) / 0.68243 For a schematic diagram of the fitting relationship, see Figure 3 .

[0096] In one embodiment, the growth inhibition parameter determined in step 2) is the turbidity of the water body. For example, for the target algae, its growth will be inhibited under a certain turbidity of the water body. In step 3), the following steps are mainly included: determining the particle size parameter and OM value of the particulate matter to be added to the water body, substituting the turbidity of the water body as the growth inhibition parameter, the particle size parameter value of the particulate matter to be added to the water body (corresponding to the particle size parameter Dx in the relationship (I)) and the OM value into the established relationship (I) to calculate the concentration of suspended particles, thereby determining the expected suspended particle concentration condition in the water body. In step 4), the required amount of particulate matter to be added is added to the water body according to the expected suspended particle concentration condition in the water body that has been determined, so as to achieve the purpose of inhibiting the growth of the target algae. In this embodiment, the suspended particle concentration required to achieve the target turbidity can be determined based on the particle size parameter value and OM value of the suspended particles combined with the turbidity of the water body as the growth inhibition parameter.

[0097] In another embodiment, the growth inhibition parameter determined in step 2) is irradiance. For example, for the target algae, its growth will be inhibited under a certain irradiance. Step 3) mainly includes the following steps: using the above irradiance as the growth inhibition parameter as the value of E(z) in relational formula (II), and determining the irradiance E(0) of the water surface of the water body, substituting E(z) and the preset depth z of the water body of E(0) into relational formula (II) to calculate the underwater light attenuation coefficient K;

[0098] Substitute the calculated underwater light attenuation coefficient K into the established relationship (III) to calculate the turbidity of the water body. Substitute the calculated turbidity of the water body, as well as the predetermined particle size parameters (corresponding to Dx in the relationship (I)) and OM value of the particles to be added to the water body, into the established relationship (I) to calculate the suspended particle concentration, thereby determining the expected suspended particle concentration conditions of the water body. Afterwards, in step 4), adding suspended particles to the water body according to the determined expected suspended particle concentration conditions of the water body can achieve the purpose of inhibiting the growth of target algae.

[0099] In another embodiment, the growth inhibition parameter determined in step 2) is the transparency of the water body. For example, for the target algae, its growth will be inhibited under a certain water transparency; or when it is inconvenient to test the turbidity but convenient to test the transparency of the water body, step 3) can be performed as follows: In step 3), the transparency of the water body as the growth inhibition parameter is substituted into the established relationship (IV) to calculate the turbidity of the water body. Then, the particle size parameter (corresponding to Dx in the relationship (I)) and the OM value of the particulate matter to be added to the water body, as well as the calculated turbidity of the water body, are substituted into the established relationship (I) to calculate the suspended particulate matter concentration, thereby determining the expected suspended particulate matter concentration condition of the water body. Afterwards, in step 4), particulate matter is added to the water body according to the determined suspended particulate matter concentration condition, so as to achieve the purpose of inhibiting the growth of the target algae.

[0100] In the method provided by the present invention, the concentration of suspended particles in the water body required to achieve the growth inhibition of the target algae can be flexibly determined through a variety of different growth inhibition parameter information, and the growth inhibition purpose of the target algae can be achieved by adding the required amount of particles, which is convenient, flexible and easy to implement. In addition, in the relationship model established by the present invention, conversion relationships can be established between turbidity and irradiance, and between turbidity and water transparency. Ultimately, the addition operation of suspended particles can be guided by the relationship between turbidity and the concentration of suspended particles, particle size parameters and OM values. The concentration of suspended particles can be determined based on the particle size parameters and OM values ​​of the particles to be added in combination with turbidity, which has a strong practical guiding role in the addition of particles and the achievement of growth inhibition of the target algae.

[0101] In a preferred embodiment, in step 4), after adding particles to the water body, the relevant parameters of the water body are continuously monitored. When the water body cannot meet the requirements of the growth inhibition parameters, particles can be added again, for example, particles to be added that meet the particle size parameters and OM values ​​in the aforementioned step 3) are added again, for example, particles deposited in the water body are resuspended, so as to reach the required suspended particle concentration again and meet the requirements of the growth inhibition parameters, so as to achieve the purpose of continuously inhibiting the growth of the target algae. Alternatively, in step 4), after adding the particles, the water body is continuously monitored. When the water body cannot meet the requirements of the growth inhibition parameters, the particle size parameters and / or OM values ​​of the particles to be added are adjusted, for example, the particle size of the particles to be added is reduced, for example, the OM value of the particles to be added is increased, etc., so as to increase the suspendability of the particles, that is, the particles to be added are reselected, and the expected suspended particle concentration conditions of the water body are re-determined according to the step 3); then particles are added to the water body according to the re-determined expected suspended particle concentration conditions of the water body.

[0102] In step 4) of the present invention, the particulate matter can be added by dry method or wet method. In step 4), the particulate matter used for addition can be selected from one or more of clay minerals, sedimentation tank sludge of water plants (such as water plants), activated sludge, bottom mud of natural water bodies and harmless industrial waste particulate matter (such as fly ash, etc.); wherein the clay mineral can be natural or commercial clay minerals, such as shore soil, sediment, kaolin, diatomaceous earth and bentonite, etc.

[0103] In order to facilitate the understanding of the present invention, the present invention will be further described below in conjunction with examples. It should be understood that the following examples are only for a better understanding of the present invention and do not mean that the present invention is limited to the following examples.

[0104] Example 1

[0105] The target algae of this example is Cladophora.

[0106] Cladophora is a filamentous green macroalgae (Chlorophyta, Cladophora family). In eutrophic lakes, filamentous cladophora often blooms, which affects the growth of submerged plants and the recovery of vegetation. Cladophora blooms also often occur in some artificial water channels. A large amount of Cladophora biomass moves downstream with hydraulic scouring, which may cause trouble for water production in water plants. Studies have found that water transparency can affect the growth of cladophora. Transparency affects underwater light intensity and thus affects algae photosynthesis. At the same time, reduced turbidity will expand the available area for cladophora to settle on the surface of aquatic plants, thereby increasing its abundance. The water transparency in which the growth of cladophora is inhibited corresponds to a water turbidity of about 20 NTU (Guo Liangliang et al. 2022).

[0107] In this example, a village with an area of ​​600m 2 The experiment was conducted in a pond with an average water depth of 2m. Six closed enclosures were built in the middle of the pond (the closed enclosures were constructed by polyethylene transparent film) for the experiment. The experimental numbers were recorded as B1 (blank control), B2, B3, B4, B5, and B6. During the experiment, the algal biomass per unit area in the enclosure was collected at a fixed time every week, and five replicate samples were taken in parallel in each enclosure. The collected Cladophora samples were rinsed with deionized water to remove attachments, and the wet weight biomass in each sample was weighed, and then the samples were dried to constant weight at 60°C, and the total dry mass in each sample was calculated according to the wet weight / dry weight ratio of the sample to estimate the biomass per unit area. The turbidity of the water body was obtained by a portable multi-parameter water quality analyzer (YSI Professional Plus), and the transparency of the water body was measured by a Secchi transparency disk. The turbidity gradient designed in this experiment was: 5NTU, 10NTU, 15NTU, 20NTU, and 25NTU. The initial turbidity of the water before the suspended particles were added to the enclosure was 2.2 NTU.

[0108] It is predetermined that the particles to be added are high-purity kaolin (Shanlin Shiyu Mineral Products Co., Ltd., purity>99.5%), whose OM value is 0 and D50 is 1μm. Substitute the initial turbidity of the water body from the above-designed turbidities, and the OM value and D50 of the suspended particles that have been determined into the relationship (I) (TUR=0.89SPM-0.08D50+6.56OM2) for calculation, and obtain the suspended particle concentrations (i.e., SPM values) corresponding to the turbidity gradients of 5NTU, 10NTU, 15NTU, 20NTU, and 25NTU designed above: 3.24mg / L, 8.85mg / L, 14.47mg / L, 22.34mg / L, and 25.70mg / L, respectively.

[0109] Add particles to the grid according to the suspended particle concentration gradient calculated above. Measure the turbidity of the water after adding particles, that is, the actual turbidity, and compare the actual turbidity with the expected turbidity (that is, the turbidity of the above experimental design), see Figure 4 ; As can be seen from the figure, although there are some deviations between the actual turbidity and the expected turbidity after adding particles, the two are very close; the reason for the deviation may be that the turbidity of the water body is not only affected by suspended particles, but also by colored dissolved organic matter in the water body and particle flocculation and other processes.

[0110] Throughout the experiment, the relationship between the estimated biomass per unit area in the enclosure and the relative turbidity was as follows: Figure 4 As shown in the middle right figure, since the added suspended particles will cause the turbidity of the enclosure to be in a changing process during the sedimentation process, multiple data on biomass corresponding to different turbidities can be obtained in the five closed enclosures. The maximum turbidity value of 26NTU in the figure appears in the 25NTU experimental group, and the minimum turbidity value of 2NTU appears in the blank control group. The results of this figure show that when the turbidity exceeds 20NTU, the biomass is maintained at a low level, indicating that the growth of Cladophora is inhibited. At the same time, when the turbidity is less than 5NTU, there is no significant difference between the biomass and the biomass of the blank control group, indicating that the biomass of Cladophora is not affected by turbidity when the turbidity is less than 5NTU. During the experiment, in the enclosures with turbidity reaching more than 10NTU, there was originally a high Cladophora biomass in the water body. After the addition of particles, the biomass began to decrease; in the enclosures with turbidity reaching 20NTU, the biomass dropped to the lowest, and in the enclosures with turbidity in the range of 10-20NTU, the biomass decreased the fastest.

[0111] From the above experimental results, it can be seen that in this embodiment, through the corresponding relationship model, based on the particle size parameters and OM value of the particles to be added and the determined growth inhibition parameters, the suspended particle concentration conditions are determined, and particles are added to the water body according to the determined suspended particle concentration conditions, which can achieve the effect of preventing and controlling the outbreak of Cladophora. In general, the simulation results of the in-situ experiment carried out in this embodiment are similar to the relationship between water turbidity and Cladophora biomass in existing studies.

[0112] Example 2

[0113] The target algae in this example is Microcystis aeruginosa (FACHB 905, from the freshwater algae species bank of the Institute of Hydrobiology, Chinese Academy of Sciences). Previous studies have found that the optimal light intensity (i.e., irradiance) for the growth of Microcystis aeruginosa is 77.4 μmol / (m 2 .s)(Chen Xuechu et al., 2007), saturation light intensity is 40-100 μmol / (m 2 .s)(Wang Chong et al., 2010).

[0114] The experiment was carried out in a 5L open beaker (i.e., culture bottle) in a light incubator. The beaker was wrapped with tin foil to avoid the influence of side light. The culture temperature was 25°C and the day-night ratio was 14h:10h. Due to the low depth of the culture bottle, the light intensity of the light incubator was set to 200μmol / (m 2 .s).

[0115] The average light intensity (i.e., irradiance) in the culture flask was designed to be 10, 20, 40, 70, 100, and 120 μmol / (m 2 .s), i.e., the design gradient of irradiance E(z). The average light intensity at 20 cm below the water surface of the culture bottle is used as the substitute depth, i.e., the preset depth z = 0.2 m. The irradiance E(0) at the water surface of the culture bottle is 200 μmol / (m 2 .s); Substitute E(z), E(0) and z into equation (II):

[0116]

[0117] The calculated K values ​​corresponding to the designed irradiances are: 15.0, 11.5, 8.0, 5.2, 3.5, 2.6

[0118] Substituting the K values ​​obtained by the above calculation into the relationship (III) (K = (2.39 ± 0.20) + (0.14 ± 0.013) × TUR), the corresponding turbidity gradients (i.e. expected turbidity) are calculated as: 90NTU, 65NTU, 40NTU, 20NTU, 8NTU, and 2NTU.

[0119] The particles to be added are the same as those in Example 1, with an OM value of 0 and a particle size D50 of 1 μm. The turbidities in the turbidity gradients calculated above and the OM values ​​and D50 of the particles that have been determined are substituted into the relationship (I) (TUR = 0.89SPM-0.08D50+6.56OM2)) to calculate the suspended particle concentrations (i.e., SPM values) corresponding to the turbidity gradients: 101 mg / L, 73 mg / L, 45 mg / L, 23 mg / L, 9 mg / L, 2 mg / L.

[0120] According to the above-calculated suspended particle concentration, a corresponding amount of particles were added to the culture bottle, and after addition, the particles were mixed evenly in a shaker and the culture of Microcystis aeruginosa was carried out. Samples were taken on the 1st, 2nd, 5th, 7th, 12th, 14th and 16th days of the experiment, and the turbidity and cell density were measured. It was found that the actual turbidity after adding the particles was very close to the expected turbidity, which was similar to the results of Example 1. During the experiment, if the turbidity was lower than the above-mentioned expected turbidity, additional particles could be added to achieve the expected turbidity.

[0121] The experimental results can be found in Figure 5 . Figure 5 The curves in the figure correspond to the cell densities measured at different experimental days in the pre-designed experimental groups of different irradiances.

[0122] from Figure 5 It can be seen that in different experimental groups, the growth of Microcystis aeruginosa under different underwater light conditions regulated by suspended particles showed great differences. The value of E(z) was 10μmol / (m 2 ·s) and 20μmol / (m 2 ·s) experimental group, the cell density was less than 1×10 6 cells / ml, indicating that the low light environment under high turbidity conditions restricts the growth of Microcystis aeruginosa. The E(z) value of adding a small amount of particulate matter is 120μmol / (m 2 ·s) also occurred in the experimental group, and the cell density was lower than that of the group with E(z) value of 40-100 μmol / (m 2 ·s) Experimental group.

[0123] It can be seen from the experimental results of this embodiment that after obtaining the optimal growth light intensity and saturated light intensity information of Microcystis aeruginosa, the irradiance parameters for inhibiting Microcystis aeruginosa can be predicted, and then through the relationship model of the present invention, the suspended particulate matter concentration conditions can be determined based on the particle size parameters and OM values ​​of the particles to be added and the determined growth inhibition parameters. Adding particles to the water body according to the calculated suspended particulate matter concentration data can achieve the purpose of inhibiting the growth of Microcystis aeruginosa.

[0124] Under laboratory conditions, the underwater light intensity was changed by controlling the turbidity and light attenuation coefficient by adding particles, and the growth of Microcystis aeruginosa under different underwater light intensities was observed. It can be found that the particle addition control method and the corresponding relationship system proposed in the present invention can effectively control the underwater light conditions. In addition, through experiments, we found that for the toxic blue algae such as Microcystis aeruginosa, low light conditions (20μmol / (m 2 ·s) or less) can effectively inhibit the growth of algae.

[0125] It is easy to understand that the above embodiments are only examples for clear explanation and do not mean that the present invention is limited thereto. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the implementation methods here. The obvious changes or modifications derived from this are still within the protection scope of the present invention.

Claims

1. A method for inhibiting the growth of target algae by adding suspended particles, characterized in that: The steps include: 1) Identify the target algae in the water body whose growth needs to be inhibited; 2) determining a growth inhibition parameter for inhibiting the growth of the target algae, wherein the growth inhibition parameter comprises at least one of turbidity, irradiance, and transparency of the water body; 3) determining the particle size parameter and OM value of the particles to be added, and determining the expected suspended particle concentration condition of the water body according to the growth inhibition parameter, the particle size parameter and the OM value; The OM value is the mass percentage of organic matter in the particulate matter; 4) Adding the particulate matter into the water body according to the expected suspended particulate matter concentration condition of the water body to inhibit the growth of the target algae.

2. The method according to claim 1, characterized in that In step 3), the growth inhibition parameter, the particle size parameter and the OM value are substituted into a pre-established relationship model to perform calculations to determine the expected suspended particulate matter concentration condition of the water body; The relationship model includes a relationship (I), which is a relationship between the turbidity of a water body and the concentration of suspended particles in the water body, the particle size parameters of the suspended particles, and the OM value of the suspended particles.

3. The method according to claim 2, characterized in that The relationship (I) is established in the following manner: Obtain multiple water samples, obtain the turbidity, suspended particle concentration and particle size parameter of each water sample, obtain the OM value of the suspended particles in each of the water samples, and obtain the relationship (I) between the turbidity and the suspended particle concentration, the particle size parameter of the suspended particles and the OM value of the suspended particles by fitting: TUR=α1SPM+α2Dx+α3OM2(I); Wherein, TUR is the turbidity of the water body, in NTU; SPM is the suspended particle concentration of the water body, in mg / L; OM2=exp(-OM); Dx is the particle size parameter of the suspended particles, in μm; α1, α2, α3 are the coefficients in the relationship (I).

4. The method according to claim 2, characterized in that: The particle size parameter is D10, D50, D60 or D90.

5. The method according to claim 2, characterized in that: The growth inhibition parameter is the turbidity of the water body. In the step 3), the turbidity of the water body as the growth inhibition parameter and the particle size parameter and OM value of the particulate matter to be added are substituted into the relationship (I) to calculate the suspended particulate matter concentration, thereby determining the expected suspended particulate matter concentration condition of the water body.

6. The method according to claim 2, characterized in that The relationship model also includes relationship formula (II) and relationship formula (III); Wherein, the relation (II) is the relation between irradiance and underwater light attenuation coefficient, and the relation (II) is: Where K is the underwater light attenuation coefficient; z is the preset depth of the water body, in m; E(z) is the irradiance of the water body at the preset depth z, and E(0) is the irradiance of the water surface. The units of E(z) and E(0) are μmol / (m 2 .s); The relational expression (III) is the relational expression between the underwater light attenuation coefficient and the turbidity of the water body.

7. The method according to claim 6, characterized in that The relationship (III) is established in the following manner: Water samples are obtained from multiple water bodies, E(0) and E(z) of each water body are obtained, and the underwater light attenuation coefficient of each water body is determined according to the relationship (II); the turbidity of each water sample is obtained, and the linear relationship between the underwater light attenuation coefficient and the turbidity of the water body is obtained by fitting according to the underwater light attenuation coefficient of each water body and the turbidity of each water sample: K=a+b*TUR(III) Wherein, TUR is the turbidity of the water body, and the unit is NTU; b is the slope of the relational formula (III), and a is the intercept of the relational formula (III).

8. The method according to claim 6, characterized in that The growth inhibition parameter is irradiance, and the irradiance is used as the value of E(z) in relational formula (II) to obtain the irradiance E(0) of the water surface of the water body, and the preset depth z, E(z), and E(0) are substituted into relational formula (II) to obtain the underwater light attenuation coefficient of the water body; Substituting the underwater light attenuation coefficient K into the relational formula (III) to calculate the turbidity of the water body; The calculated turbidity of the water body and the particle size parameters and OM value of the particles to be added are substituted into the relationship (I) to calculate the suspended particle concentration, thereby determining the expected suspended particle concentration conditions of the water body.

9. The method according to claim 2, characterized in that: The relationship model also includes a relationship formula (IV), which is a relationship formula between the turbidity of a water body and the transparency of the water body.

10. The method according to claim 9, characterized in that The relationship (IV) is established in the following manner: The turbidity and transparency of each water sample are obtained, and the values ​​of the turbidity and the transparency are respectively transformed into lg logarithms and then linearly fitted to obtain the relationship between the turbidity and transparency of the water body: log(SDD)=a+b×log(TUR) (IV) Wherein, SDD is the transparency of the water body, in cm; TUR is the turbidity of the water body, in NTU; b is the slope of the relationship (ⅠⅤ), and a is the intercept of the relationship (ⅠⅤ).

11. The method according to claim 9, characterized in that The growth inhibition parameter is the transparency of the water body. In the step 3), the transparency of the water body as the growth inhibition parameter is substituted into the relational formula (IV) to calculate the turbidity of the water body. The calculated turbidity of the water body and the particle size parameters and OM value of the particles to be added are substituted into the relationship (I) to calculate the suspended particle concentration, thereby determining the expected suspended particle concentration conditions of the water body.

12. The method according to any one of claims 1 to 11, characterized in that: In step 4), after adding the particulate matter, the water body is continuously monitored, and when the water body fails to meet the requirement of the growth inhibition parameter, the particulate matter is added again; Alternatively, in step 4), after adding the particulate matter, the water body is continuously monitored, and when the water body cannot meet the requirements of the growth inhibition parameters, the particle size parameters and / or OM values ​​of the particulate matter to be added are adjusted, and the expected suspended particle concentration conditions of the water body are re-determined according to step 3); and then, particulate matter is added to the water body according to the re-determined expected suspended particle concentration conditions of the water body.

13. The method according to any one of claims 1 to 11, characterized in that: In step 4), the particles are added by dry or wet method; And / or, in step 4), the particulate matter to be added is selected from one or more of clay minerals, sludge from sedimentation tanks of water plants, activated sludge, bottom mud of natural water bodies and harmless industrial waste particulate matter.

14. Use of the method according to any one of claims 1 to 13, characterized in that: The method is applied in algal bloom prevention and control or water quality regulation.

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