CN115088720B

CN115088720B - Sophorolipid-based azolla killing agent

Info

Publication number: CN115088720B
Application number: CN202210569181.4A
Authority: CN
Inventors: 马晓静; 邵君前; 方向东; 荀尚培; 程旭
Original assignee: Hefei University of Technology
Current assignee: Hefei University of Technology
Priority date: 2022-05-24
Filing date: 2022-05-24
Publication date: 2023-10-10
Anticipated expiration: 2042-05-24
Also published as: CN115088720A

Abstract

The application belongs to the technical field of environmental ecological protection, and provides a sophorolipid-based azolla killing agent, which comprises the following raw materials: sophorolipid, ethanol and water, comprising the following preparation steps: step 1, dissolving sophorolipid produced by candida globosa in ethanol to prepare mother liquor; and 2, adding water into the mother liquor, and then stirring by using a stirrer until the killing agent is formed. The method provided by the application has the advantages of strong killing effect, high action speed, no odor of the treated water body, long control and killing time, low treatment cost, no secondary pollution and the like, can realize large-scale treatment, and can be added into the water body which is propagated by the duckweed in a flooding way in the past year in advance or directly added into the water body which is not grown by the duckweed in a flooding way, and the method also has a good prevention and control effect.

Description

Sophorolipid-based azolla killing agent

Technical Field

The application belongs to the technical field of environmental ecological protection, and particularly relates to a sophorolipid-based azolla killing agent.

Background

Landscape water bodies, such as small rivers, ecological ponds and the like which are constructed and beautified artificially, are important methods for increasing the environment grace and purifying the ecology of cities. However, the manually reformed water body is in a closed or semi-closed state generally, so that the fluidity of the water body is small; and the ecological structure is single, the self-cleaning capability of the water body is poor, so that once the water body is polluted by the outside, the self-recovery is difficult to complete.

Azolla (Soirodela polyrhiza) is a more common aquatic plant, particularly in paddy fields, ponds, streams and the like. Azolla is one of the natural baits of some edible fishes (non-filter-feeding fishes, such as grass carp, bream, crucian, etc.). For a wild water body, a certain amount of duckweed is beneficial to the growth and propagation of fishes, but excessive propagation of duckweed can cause full coverage of the water surface of the water body, seriously affect the gas exchange between the water body and the outside, and can also block sunlight from irradiating the water body, so that the oxygen content in the water body is greatly reduced, and the phenomena of oxygen deficiency and even pond turning of fishes, shrimps and shellfishes in the water body are finally caused. Therefore, duckweed in the fish pond needs to be reasonably controlled to avoid the phenomenon.

Currently, manual salvaging is still the most dominant emergency treatment method for duckweed. The method has the defects of low salvaging efficiency, heavy workload and the like; the duckweed can reproduce surprisingly, and after salvaging, the duckweed can be spread over the whole water surface again under the proper temperature and illumination condition for 1-2 weeks, so that the symptoms and root causes are not treated.

In order to solve the problems, various special equipment for fishing duckweed is developed, for example, patent application number CN202120571745.9 discloses a duckweed collecting device arranged on a ship body, and the device has the advantages of automatic fishing, high flexibility, low labor intensity, convenience in use, good stability and the like; patent application number CN202120236877.6 discloses a duckweed salvage device capable of preventing salvage from overflowing and flexible and convenient to use. However, due to the diversity and complexity of the water environment in which duckweed grows, such as small-sized swamps, paddy fields and the like, the adaptability of many devices is poor, and the use is difficult, so that the duckweed cannot be effectively popularized.

The biological duckweed control method is mainly used for controlling the overgrowth and propagation of duckweed by the food chain principle, and is the safest duckweed control method. The measure of biologically controlling and killing duckweed mainly by the stocking of aquatic animals (such as silver carp, bighead carp, daphnia magna, and the like) can not cause ecological damage, but has the problems of slow effect, low efficiency, and the like.

In addition, chemical duckweed killers, such as copper sulfate, quicklime, and the like, are also used to control duckweed growth. Although the chemical duckweed killing agent has a certain duckweed killing effect, the chemical duckweed killing agent cannot be used for treating drinking water, and is easy to produce secondary pollution in the use process, so that the environmental safety of the water is negatively influenced.

The natural degradable biological duckweed killing agent which is derived from biology (especially plants and microorganisms) provides a new idea for solving the problems. For example, patent application number CN201610128083.1 discloses a herbicide prepared from natural medicinal plants and a compound bacteria preparation, and has remarkable killing effect on duckweed. However, the introduction of the bacterial preparation may break the balance between the original bacterial groups, and there is a certain use risk.

In order to solve the problems, the application provides a sophorolipid-based azolla killing agent which can be used for emergency killing of duckweed and prevention and control of duckweed growth.

Disclosure of Invention

The application aims to solve the technical problems in the prior art and provides a sophorolipid-based azolla killing agent.

In order to achieve the above purpose, the application adopts the following technical scheme: an azolla killing agent based on sophorolipid comprises the following raw materials: sophorolipids, ethanol and water, and comprises the following preparation steps:

step 1, dissolving sophorolipid produced by candida globosa in absolute ethyl alcohol to prepare mother liquor;

and 2, adding water into the mother liquor, and then stirring by using a stirrer until the killing agent is formed.

In a preferred embodiment of the present application, the sophorolipids are crude sophorolipid fermentation products, pure products of lactone type sophorolipids, or a mixture of lactone type sophorolipids and acid type sophorolipids mixed in different proportions.

In a preferred embodiment of the present application, the volume ratio of the crude sophorolipid fermentation product, absolute ethanol and water is 1:0.1-0.4:4-10, wherein the content of the crude sophorolipid fermentation product is 40-60%.

In a preferred embodiment of the present application, the volume ratio of the crude sophorolipid fermentation product, absolute ethanol and water is 1:0.15-0.2:5-8, wherein the content of the crude sophorolipid fermentation product is 40-60%.

In a preferred embodiment of the present application, the stirring speed is 50 to 200r/min and the stirring time is 2 to 8min.

In a preferred embodiment of the present application, the stirring speed is 60 to 100r/min and the stirring time is 3 to 5min.

In a preferred embodiment of the application, the method of use is: the prepared killing agent is added into the knapsack electric sprayer according to the actual volume of the water body, and then the mixture is sprayed into the water body through the knapsack electric sprayer.

In a preferred embodiment of the application, in step 1, the concentration of sophorolipid is controlled to be 60-150 mg/L when the duckweed killing effect is achieved; the sophorolipid concentration is 10-50 mg/L when the duckweed growth inhibition effect is achieved.

The principle and the beneficial effects of the application are as follows: the duckweed killing agent takes secondary metabolite sophorolipid generated by fermentation of candida globosa as an effective duckweed killing substance, overcomes the defects of high environmental toxicity, short duration, low prevention and control efficiency and the like of chemical agents and biological control killing methods, and achieves the purposes of quick killing of duckweed and continuous inhibition of duckweed growth. The method for preventing and controlling the water duckweed from flooding has the characteristics of high efficiency, durability and the like, and has important practical significance for environmental protection, aquaculture and the like.

Additional aspects and advantages of the application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the application.

Drawings

The foregoing and/or additional aspects and advantages of the application will become apparent and may be better understood from the following description of embodiments taken in conjunction with the accompanying drawings in which:

FIG. 1 shows the killing effect of duckweed killers based on sophorolipids at 100mg/L and 50mg/L for duckweed at high and low densities.

Fig. 2 is a graph showing the change of COD, ammonia nitrogen, total nitrogen and total phosphorus in the water body under the conditions of each embodiment.

Detailed Description

Embodiments of the present application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative only and are not to be construed as limiting the application.

In the description of the present application, unless otherwise specified and defined, it will be understood to those skilled in the art that the specific meaning of the terms described above will be understood as appropriate.

The application provides a sophorolipid-based azolla killing agent, which comprises the following raw materials: sophorolipids, ethanol and water.

In this example, sophorolipid is a secondary metabolite obtained by fermentation of candida globosa strains with glucose and vegetable oil, and sophorolipid may be a crude product of sophorolipid fermentation, a pure product of lactone type sophorolipid (purity of 95% or more), or a mixture of lactone type sophorolipid and acid type sophorolipid mixed in a volume ratio of 1:1. The ethanol is absolute ethanol.

The preparation is carried out according to the actual demand, and comprises the following steps:

step 1, selecting sophorolipids with different concentrations according to the killing requirement or the inhibiting requirement, wherein the concentration of the sophorolipids is as follows: 60-150 mg/L, which inhibits the demand, the concentration of sophorolipid is: 10-50 mg/L. And dissolving sophorolipid in absolute ethanol with minimum volume (used as cosolvent) to prepare mother liquor. The volume ratio of the sophorolipid to the absolute ethyl alcohol is 1:0.1-0.04.

Step 2, adding water into the mother solution, wherein the volume ratio of sophorolipid to water is 1: 4-10 (i.e. the volume ratio of sophorolipid, absolute ethyl alcohol and water is 1:0.1-0.4:4-10), and then stirring by using a stirrer until the killing agent is formed. In this example, the stirring speed was 50 to 200r/min and the stirring time was 2 to 8min.

In yet another embodiment of the present application, the killing agent of the present application is formulated as a kit.

The preparation method comprises the following steps of:

step 1, the concentration of sophorolipid is 80-120 mg/L (for killing), 20-50 mg/L (for preventing and curing), ethanol is absolute ethanol, and the adding amount of the cosolvent is sophorolipid: absolute ethyl alcohol=1:0.15-0.02, and sophorolipid is added into absolute ethyl alcohol to prepare mother liquor.

And 2, adding water (water is natural water in the implementation site, such as lake water, pool water and the like) into the mother liquor, stirring at a stirring speed of 50-200 r/min for 3-5 min, and uniformly mixing until the killing agent is formed.

In the above embodiments, the method of using the killing agent: the prepared killing agent is added into the knapsack electric sprayer according to the actual volume of the water body, and then the mixture is sprayed into the water body through the knapsack electric sprayer.

The experimental mode is as follows:

experiment 1:

the preparation method of the duckweed killer comprises the following preparation steps:

(1) Taking 6.9L of sophorolipid stock solution with concentration of 547g/L, adding 1.035L of absolute ethyl alcohol as cosolvent, stirring at 200r/min for 5min, and stirring to mix uniformly.

(2) Slowly pouring the stirred sophorolipid-ethanol stock solution into natural water with the volume of 8 times to form a three-substance composite system.

The duckweed killing and growth inhibition experiment is carried out by using the prepared duckweed killing agent, wherein the duckweed killing agent is added into a water body in a pond with the depth of 10 multiplied by 8.3m and the water depth of 1.5m, the concentration of the duckweed killing agent is controlled to be 100mg/L, the duckweed killing agent is uniformly sprayed and added into the pond by using a backpack electric sprayer, the duckweed is spread over the whole water surface, the duckweed killing agent is observed once every 1 day in the first 3 days, and the duckweed killing agent is observed once every 2 days in the last 11 days. As can be seen from the attached figure 1, for the duckweed killer with the sophorolipid concentration of 100mg/L, the duckweed killing rate reaches 80% in 7 days; after 14 days of continuous observation, the killing rate of duckweed reaches 100%.

Experiment 2:

the preparation method of the duckweed killer comprises the same preparation steps and experimental conditions as in experiment 1, and is characterized in that the concentration of the sophorolipid is 547g/L, the adding amount of the sophorolipid is 3.45L, the duckweed killer is sprayed into water body which is full of the water surface after the preparation, the concentration of the sophorolipid of the duckweed killer is controlled to be 50mg/L, so that the inhibition effect of the duckweed killer on the growth is explored, the duckweed killer is observed once every 1 day in the first 3 days, and the duckweed killer is observed once every 3 days in the last 11 days. The field experiment result shows that when duckweed killers with the sophorolipid concentration of 50mg/L are used, the number of duckweed is not increased within 7 days, and the color of duckweed is changed from green to yellow; after 14 days of continuous observation, a slight decrease in the amount of duckweed was found. Therefore, the treatment concentration of duckweed which is fully distributed on the water surface should reach more than 50mg/L.

Experiment 3: the preparation method of the duckweed killer is the same as that of experiment 1 in preparation steps and experimental conditions, and is different in that the concentration of the duckweed killer is 547g/L, the adding amount of the sophorolipid is 3.45L, the duckweed killer is added into a water body which is only fully distributed on 1/5 water surface after the preparation is finished, the total concentration of the sophorolipid is controlled to be 50mg/L, so that the inhibition effect of the duckweed killer with the concentration of the sophorolipid of 50mg/L on proliferation of duckweed is explored. The first 3 days were observed every 1 day, and the second 11 days were observed every 2 days. The duckweed killing agent with the concentration of sophorolipid of 50mg/L applied at one time has excellent control effect on duckweed growth and reproduction. The duckweed quantity is not increased within 7 days, the duckweed color is changed from green to yellow, and the inhibition rate of proliferation of duckweed reaches 100%; after 14 days of continuous observation, the duckweed proliferation inhibition rate can still be kept 100%.

Comparative cases:

the control was performed in a pond with 10X 8.3m and a depth of 1.5m, with the initial duckweed being placed over approximately 1/5 of the water surface. The pond water body is not treated, the original growth condition of duckweed is maintained, and the pond water body is continuously observed for 14 days. The field experiment result shows that the duckweed is fully distributed on the water surface of about 1/2 after 7 days, and the duckweed is fully distributed on the whole water surface after 14 days, so that the duckweed grows and grows vigorously and has good state.

Experiments of the application show that the duckweed killing agent which takes sophorolipid as a main duckweed killing substance has good capability of killing and preventing duckweed from excessive proliferation, and the total nitrogen, the total phosphorus and the ammonia nitrogen of a water body are not increased in a short time after the duckweed killing agent is added, as shown in figure 2.

The foregoing is merely a preferred embodiment of the present application, and it should be noted that the above-mentioned preferred embodiment should not be construed as limiting the application, and the scope of the application should be defined by the appended claims. Modifications and alterations may be made without departing from the spirit and scope of this application, and such modifications and alterations should also be considered as being within the scope of this application.

In the description of the present specification, reference to the terms "preferred implementation," "one embodiment," "some embodiments," "example," "a particular example" or "some examples" and the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the application. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the application, the scope of which is defined by the claims and their equivalents.

Claims

1. The sophorolipid-based azolla killing agent is characterized by comprising the following raw materials:

sophorolipids, ethanol and water; the sophorolipid is an industrial sophorolipid fermentation crude product with the content of 40-60%; the ethanol is absolute ethanol;

the volume ratio of the industrial sophorolipid fermentation crude product with the content of 40-60 percent to the absolute ethanol to the water is 1:0.1-0.4:4-10.

2. The sophorolipid-based azolla killing agent according to claim 1, wherein the volume ratio of the crude product of industrial sophorolipid fermentation, absolute ethanol and water is 1:0.15-0.2:5-8, and the content is 40-60%.

3. The sophorolipid-based azolla killing agent according to claim 2, which is prepared by the following method:

step 1, dissolving an industrial sophorolipid fermentation crude product produced by candida globosa in absolute ethyl alcohol to prepare mother liquor;

4. The sophorolipid-based azolla killing agent according to claim 3, wherein the stirring speed is 50-200 r/min and the stirring time is 2-8 min.

5. The sophorolipid-based azolla killing agent according to claim 4, wherein the stirring speed is 60-100 r/min and the stirring time is 3-5 min.