JP5707956B2 - Algae suppression method and algae inhibitor - Google Patents

Description

  The present invention relates to an algae suppression method and an algae inhibitor, and specifically relates to a technique capable of efficiently suppressing the generation of algae without requiring complicated management and great cost.

  The supply of nutrient salts such as nitrogen and phosphorus from the basin is increasing the number of lakes and closed seas that are gradually eutrophied. In such lakes and closed waters, algae growth is a problem. As algae grows and proliferates, the water quality in the water area worsens, and phenomena such as hypoxia, aquatic organisms killed by algae-derived harmful substances, reduced transparency, and generation of odors are observed. Therefore, as a technology for controlling such algae (phytoplankton), for example, direct purification of sand cover, dredging, or water in the bottom mud for the purpose of reducing the inflow load of nitrogen, phosphorus, etc. from the basin, and suppressing the elution of nutrient salts, etc. There was a technique such as.

  In addition, an artificial floating island composed of a vegetation base made of a porous material having a three-dimensional network structure and a supporting means for supporting the vegetation base in a state of floating in water, the vegetation base suppresses the growth of phytoplankton. Artificial floating islands (see Patent Document 1) characterized by planting a water extraction plant selected from Himegama, Kusasayoshi, Makomo, and Kasasuge that release allelopathic substances have also been proposed. In addition, an artificial floating island comprising a vegetation base and support means for supporting the vegetation base in a state of floating in water, wherein a water extraction plant that releases an allelopathic substance that suppresses the growth of phytoplankton is planted on the vegetation base. Artificial floating islands (see Patent Document 2) characterized by planting have also been proposed.

Japanese Patent No. 4456654 JP 2010-213578 A

  However, in order to implement the above-described method for reducing the inflow load of nitrogen, phosphorus, etc. from the basin, it is necessary to work on water purification in the entire basin, and due to the relationship with governmental measures, etc. May take a long time. Moreover, although the method of covering sand and dredging in the bottom mud is effective immediately, there is a problem that the effect disappears with time unless the environment of the basin is improved. In addition, a direct water purification method that removes suspended matter and nutrients contained in water is immediately effective, but it is a method that requires enormous costs to continue operation and is difficult to apply widely. Met.

  On the other hand, when employing techniques such as those exemplified in Patent Documents, the water level of the artificial floating island also fluctuates due to fluctuations in the water level of the target water area, and there is a concern that the growth of the extraction plants planted on the artificial floating island may be irregular. . Moreover, when adjusting the location of the artificial floating island at any time in order to cope with this concern, very complicated management will be needed.

  Then, this invention aims at provision of the technique which can suppress generation | occurrence | production of algae efficiently, without requiring complicated management and a big cost.

The algal control method of the present invention that solves the above problems adjusts the planting density to 2 to 5 g / L on the bottom of a closed water area where new water does not flow, which is the target of algal control, for the algal pathogenic effect. And planting. According to this, the allelopathic substance eluted from kawaturum acts on various algae present in the water area, and the generation thereof can be effectively suppressed. Moreover, the kawaturum planted on the bottom of the water will settle and continue to grow naturally, so that the allelopathic substance will continue to elute into the water area without special management or cost reduction. Moreover, the allelopathic substance that elutes from kawaturum is a natural product derived from kawaturum, which is naturally decomposed over time, remains unnecessarily for a long period of time, and has little concern about other adverse effects. Therefore, the generation of algae can be efficiently suppressed without requiring complicated management and great costs.

Moreover, the algal suppression method of this invention adjusts the planting density to 2-5 g / L, and the culture solution obtained by culture | cultivating the kawaturmo which has an allelopathic effect for 6 days or more is the water area used as the suppression target of algae. It is characterized by being introduced into According to this, the allelopathic substance which elutes from kawarurumo and is contained in a culture solution acts on various algae which exist in a water body, and can suppress the generation | occurrence | production effectively. Even if the environment of the target water area (water depth, water flow, water quality, etc.) is a severe environment for the establishment of kawarumo , it is not affected by such an environment, and it is possible to effectively suppress the generation of algae just by introducing a culture solution. . Moreover, the culture solution can be easily produced simply by cultivating kawaturume for 6 days or more , and the labor and cost for production can be kept low. Further, the allelopathic substance derived from kawaturum contained in the culture solution is a natural product derived from kawaturum , which is naturally decomposed with the passage of time, and remains unnecessarily for a long time, and there is little concern about other adverse effects. Therefore, the generation of algae can be efficiently suppressed without requiring complicated management and great costs.

In addition, the algal inhibitor of the present invention is a culture solution obtained by cultivating kawaturmo having an allelopathic effect by adjusting the planting density to 2 to 5 g / L and culturing for 6 days or more . According to such an algae inhibitor, it is possible to very easily realize the allelopathic substance to be dropped into the water area where the generation of algae is desired to be suppressed. In addition, if the alga inhibitor is produced by intensively cultivating kawarumo at an appropriate facility, the production cost and labor can be further reduced, and effective algal inhibition can be realized with low cost and less labor. .

  According to the present invention, the generation of algae can be efficiently suppressed without requiring complicated management and great costs.

It is a figure which shows the example 1 of application of the algae suppression method in this embodiment. It is a figure which shows the example 2 of application of the algae suppression method in this embodiment. It is a graph which shows the relationship between the culture | cultivation period and the turbidity of a test solution obtained by the pond water single culture | cultivation test in this embodiment. It is a graph which shows the relationship between the culture | cultivation period and the turbidity of a test solution obtained by the co-culture test and the transplant water culture test in this embodiment. It is a graph which shows the influence of the amount of Kawarumoru on co-culture in the influent water of this embodiment. It is a graph which shows the influence of the amount of kawaturum on the transplant water culture in the inflow water of this embodiment. It is a graph which shows the relationship between the elapsed days in this embodiment, and turbidity.

  Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram illustrating an application example 1 of the algal control method according to the present embodiment. In the present embodiment, for example, kawarumo is planted as a submerged plant 3 having an allelopathic effect on the bottom 2 of the water area 1 where the generation of algae should be suppressed. However, the submerged plant 3 is not only planted directly on the ground of the bottom 2, but also can be assumed to be planted in a container having an appropriate amount of soil and then submerged and fixed to the bottom 2.

  The river spider 3 planted on the bottom 2 will be rooted on the bottom 2 and will continue to grow on the spot. Further, from the Kawaturumo 3, a substance having an allelopathic effect, that is, an allelopathic substance (allerochemical) is eluted in water. This allelopathic substance is a substance that suppresses the growth of other plants, and is probably a kind of organic matter. The allelopathic substance eluted from the kawaturum 3 diffuses into the water area 1 around the kawaturum and acts on algae floating in the water area 1. Various algae on which allelopathic substances have acted reduce their activity and suppress their growth.

  On the other hand, the Kawatsurumo 3 is located at the bottom 2 and grows by receiving photosynthesis through sunlight and continuously releasing allelopathic substances to the surroundings. That is, the elution of allelopathic substances into the water area 1 continues without special management or cost reduction. Further, the allelopathic substance eluted from the submerged plant, Kawarumurum 3, is a plant-derived natural product, which is naturally decomposed with the passage of time and remains unnecessarily for a long period of time with little concern for other adverse effects. Therefore, the generation of algae can be efficiently suppressed without requiring complicated management and great costs.

  In addition, regarding the planting density of the plant which has an allelopathic effect, according to the verification test mentioned later, the density (the weight of the Kawatsurumo 3 which exists in the water bottom 1 of the water area 1) the Kawatsurumo which is the submerged plant 3 is planted. Was preferably 1 g / L or more and less than 10 g / L, more preferably 2 g / L or more and less than 5 g / L. However, in the verification test, the experiment was conducted in a closed system (in the flask) with a very limited volume, and if it is an actual lake or a closed sea where there is a new inflow, etc., it is 10 g / L or more. High-density planting may be a suitable condition. Moreover, when the submerged plant 3 to employ | adopt is plants other than a Kawaturumo, it is estimated that the value of the preferable planting density mentioned above also differs. Anyway, a preferable planting density will differ according to the environment of the actual water area 1 and the nature of the submerged plant 3 to be planted.

  In addition, the algae (phytoplankton) that can be expected to be suppressed by the present embodiment are crypto algae, dinoflagellates, diatoms, Euglena algae, prasino algae, and cyanobacteria, and the test solution used in the verification test described later. Actually included.

  In addition, it is assumed that the water area 1 in which measures for algae suppression are taken is already eutrophied and the degree of pollution is severe. Under such circumstances, since the nutrients are constantly eluted from the bottom mud 10 and supplied to the algae, even if the submerged plant 3 is planted as it is, a lot of nutrient salts are obtained. It is difficult to efficiently control actively growing algae.

  Therefore, as shown in FIG. 2, the surface of the bottom mud 10 is covered with sand 11, that is, covered with sand, so that elution of nutrient salts and the like from the bottom mud 10 is stopped, and the submerged plant 3 is planted thereon. Is preferable. Alternatively, it is also preferable to perform dredging to remove the bottom mud itself, thereby removing nutrient salts and the like from the water area 1 and then planting the submerged plant 3 thereon.

  According to this, even if the bottom 2 is already covered with a large amount of nutrients and organic matter, it is prevented that they soar and diffuse in the water, or the bottom mud itself is tricked to nourish. The submerged plant 3 can be planted after removing salt and the like once. Accordingly, it is possible to suppress algae by the allelopathic substance of the submerged plant 3 after eliminating the adverse effects caused by the nutrient salts and the like that have been accumulated so far, and effective algae suppression corresponding flexibly to the current state of the target water area 1 Is realized.

  In the examples described above, it is assumed that the submerged plant 3 is planted on the bottom 2. However, unlike these assumptions, algae can be suppressed by introducing a liquid 20 containing an allelopathic substance derived from a submerged plant into the water area 1. In this case, the submerged plant 3 having an allelopathic effect, for example, a kawaturum, is immersed for a predetermined period, and the liquid 20 after the kawaturum is removed is poured from, for example, a predetermined tank 15 into the water area 1 to be a target of algae suppression. . According to this, the allelopathic substance eluted from the submerged plant 3 and contained in the liquid 20 acts on various algae present in the water area 1, and the generation thereof can be effectively suppressed. Even if the environment (water depth, water flow, water quality, etc.) of the target water area 1 is a severe environment for the settlement of the submerged plant 3, it is not affected by such an environment, and the generation of algae can be effectively suppressed by simply introducing the liquid 20. can do.

  In addition, the liquid 20 can be generated simply by immersing the submerged plant 3, and the labor and cost for generation can be kept low. Moreover, the allelopathic substance derived from a submerged plant contained in the liquid 20 is a plant-derived natural product, which is naturally decomposed with the passage of time, and remains unnecessarily for a long period of time. Therefore, the generation of algae can be efficiently suppressed without requiring complicated management and great costs. As described above, the liquid 20 may be charged after the bottom mud 10 of the water area 1 is covered with sand or dredged.

  The liquid 20 can be said to be an algae inhibitor formed by immersing the submerged plant 3 having an allelopathic effect for a predetermined period. According to such an algae inhibitor, it is possible to very easily realize the allelopathic substance dropping into the water area 1 where the generation of algae is desired to be suppressed. Moreover, if the submerged plant 3 is immersed in an appropriate facility (such as a factory facility that performs a large-scale immersion operation) and the algae inhibitor is generated, the generation cost and labor per unit amount are further reduced. Therefore, effective algal control can be realized with low cost and little effort. The liquid 20, that is, the algae inhibitor is not only used alone, but is additionally introduced into the water area 1 when the algae suppression effect is insufficient only by planting the submerged plant 3 on the bottom 2. It may be used in.

--- Outline of verification test of allelopathic effect by submerged plants ---
Then, since the verification test was done about the allelopathic effect which the submerged plant 3 has, the verification result is demonstrated. In the verification test, a pond into which water containing a large amount of substances such as nitrogen and phosphorus actually flows (hereinafter referred to as A pond) and a pond with inflow from this A pond (hereinafter referred to as B pond). The pond water was collected, and the kawarumo, which is one of the submerged plants 3, was placed in these pond waters, and culture tests were conducted under various conditions.

  As a culture test, a co-culture test and a transplanted water culture test were performed. In the co-culture test, cultivated pond water is coexisted in pond water, and the result is compared with cultivated pond water alone to grasp the influence of cultivated phytoplankton in pond water. On the other hand, in the transplanted water culture test, the culture solution is filtered after a predetermined number of days of the above-mentioned co-culture test, and the obtained filtered water (referred to as transplanted water) is inoculated with phytoplankton inoculum (this time filtered water). And the same amount of inflow water to the pond A) and culture. In addition, the growth suppression of phytoplankton is influenced by light intensity inhibition, nitrogen and phosphorus absorption competition, and zooplankton ingestion damage, in addition to the allelopathic effect of kawaturum. Therefore, in order to clarify the allelopathic effect excluding these factors, the above-mentioned transplanted water culture test was carried out.

--- Test sample ---
The following three samples were used as water samples, i.e., pond water samples, for the verification test.
(1) Inflow water (Inflow water of A pond)
(2) Outflow water (Outflow pond water of A pond)
(3) Pond water of the B pond Each of these pond water samples is stored in a refrigerator at 4 ° C, and each time it is used, it passes through a 2 mm mesh sieve to remove unnecessary substances such as dust, and it is used as a test solution. It was. In addition, the said A pond is a pond which is located in the back of a bay and makes pond water with the brackish water taken from the vicinity. The water quality of the inflow water to the pond A was about 20 ‰ for salt, about 1 ppm for nitrogen, about 0.2 ppm for phosphorus, and about 5 ppm for COD (Chemical Oxygen Demand). The phytoplankton contained in the influent water and expected to be suppressed by the allelopathic substance derived from the submerged plant were cryptoalgae, dinoflagellates, diatoms, Euglena algae, prasinoalgae, and cyanobacteria.

  Moreover, as a submerged plant 3 thrown into the said pond water sample, the kawaturmo is employ | adopted as an example. This kawaturum was collected in the A pond. In use, the adhering matter (fallen leaves, stingrays, etc.) was washed off and the wet weight was measured before being used for the experiment.

---- Test method (pond water single culture test, kawarumo co-culture test) ---
Then, the test method of a pond water independent culture test and a Kawaturumo coculture test is demonstrated. In this case, after putting the test solution (1000 mL) into an Erlenmeyer flask (1 L volume), a predetermined amount (0, 2, 5, 10 g) of kawaturum is added and cultured. Among these, the case where the amount of kawaturum is 0 g is referred to as a pond water single culture test, and the case where kawaturum is added in amounts of 2, 5, and 10 g is referred to as a kawaturum coculture test. The culture is performed in an existing lighting culture facility.

In addition, after the culturing period of 16 days has elapsed, 1 ppm of D · TN (dissolved nitrogen) and 0.5 ppm of D · PO 4 -P (dissolved phosphorous) with respect to the remaining amount of the culture broth After addition, cultivation was further continued for 7 days. The final total culture period is 21 days. The culture conditions are shown below.
-Culture temperature: 25 ° C
・ Illumination: 4000 lx
-Light / dark cycle: 14-hour light condition, 10-hour dark condition-Culture method: Stationary culture-Sample agitation: Manual agitation once a day

--- Test method (Transplantation water culture test) ---
In this case, the culture solution 6 days after the start of the co-culture in the above-described co-culture test is used as transplantation water. This transplanted water is a filtrate obtained by removing kawaturum from the culture solution obtained after 6 days in the co-culture test and further filtering with filter paper (5C). After adding the same amount of inflow water (inflow water flowing into the pond A) to this transplanted water, culturing is performed for 10 days under the same conditions as in the above-mentioned co-culture test.

  In addition, after the start of this culture and the total number of culture days has elapsed, after 16 days have elapsed, 1 ppm of D · TN and 0.5 ppm of D · PO4-P are added to the remaining amount of the culture solution, and further cultured for 7 days. Carried out.

  The culture conditions at this time are the same as those of the above-mentioned pond water single culture test and kawarumo co-culture test. In addition, 6 days after the start of the co-culture test is the first step, and the period (10 days) of the transplant water culture test in which the culture solution on the 6th day after the start of the co-culture test is used as the transplant water is the first step. 2 steps, after a total of 16 days has elapsed, add 1 ppm of D · TN and 0.5 ppm of D · PO4-P to the remaining amount of the culture solution, and further carry out a culture test period (7 days) This is called the third step.

--- Combination of test solution and test ---
As described above, the water used for the test, that is, the test solution, is the inflow water flowing into the A pond, the outflow water flowing out from the A pond, and the pond water of the B pond, as shown in Table 1 below. Each culture test was carried out under each condition of 1) to (12).

  In addition, Table 2 shows the analysis results of the water quality of each pond water of the pond water of the A pond and the pond water of the B pond, which are the test solutions.

  As shown in Table 2, in terms of turbidity, the influent water of the A pond was “7.3” degrees, the effluent water was “6.4” degrees, and the pond water of the B pond was “4.5” degrees. . Regarding COD, the influent water of the A pond was “5.0” mg / L, the effluent water was “8.9” mg / L, and the pond water of the B pond was “24” mg / L. In addition, regarding the nitrogen content of the dissolved matter, the influent water of the A pond is “0.95” mg / L, the effluent water is “0.59” mg / L, and the pond water of the B pond is “1.0” mg / L. Met. In addition, regarding the phosphorous content of the dissolved phosphoric acid body, the influent water of the A pond is “0.17” mg / L, the effluent water is “0.24” mg / L, and the pond water of the B pond is “0.77” mg / L. / L.

---- Test results (pond water single culture test) ----
The test results of the pond water single culture performed under the above conditions are shown below. FIG. 3 is a graph showing the relationship between the culture period and the turbidity of the test solution obtained by the pond water single culture test. As shown in this graph, in the condition (1): influent water, the turbidity increased from 2 days and reached a maximum of 28 degrees after 4 days, and then gradually decreased until the 11th day. In contrast, the turbidity was almost unchanged in condition (4): effluent, and the turbidity did not increase even after 16 days of culture in condition (5): N added. In addition, in the condition (6): B pond, the turbidity hardly increased.

  As described above, the AGP (AlgalGrowthPotential) of the influent water was calculated to be 28 degrees in terms of turbidity, but the turbidity of the local effluent after the water flowed down the pond A was as low as 6.4 degrees. In the pond A, it is considered that some action that suppresses the growth of suspended phytoplankton is acting.

  In addition, the AGP is only 5 to 6 degrees in turbidity, even though the nitrogen and phosphorus concentrations in the effluent to which the nitrogen content is added and the B pond are equal to or exceeding the inflow water. Absent. From this, it is considered that some action that suppresses the growth of phytoplankton works in the ponds A and B.

  The pond A has aquatic winged spiders, and the pond B has algae shark spiders. Both aquatic organisms are involved in inhibiting the growth of phytoplankton, secreting some kind of allelopathic substance, It is expected that the growth of phytoplankton is suppressed.

---- Test results (co-culture / transplant water culture test) ----
Subsequently, the results of the co-culture test and the transplanted water culture test will be described. FIG. 4 is a graph showing the relationship between the culture period and the turbidity of the test solution obtained by the co-culture test and the transplanted water culture test. In this graph, the test results are also shown for the conditions (1) to (3) in the sense of comparison with the case where an allelopathic substance derived from kawaturum is included in the test solution.

a. Change over time in co-culture Condition (1): In the case of influent water alone, the turbidity of the test solution increased from 2 days after the start of the culture, and reached a maximum of 28 degrees after 4 days. On the other hand, under the condition (8): Kawamuro 5 g / L, the turbidity remained at 4 to 5 degrees even after 4 to 5 days from the start of the culture. In addition, both nitrogen and phosphorus were reduced even under condition (7): Kawatsurumo 2 g / L, but turbidity was 11 to 11 between the condition (1): influent water alone and condition (8): 5 g / L. It was 15 degrees. Thus, the increase in turbidity was suppressed in the co-culture of kawaturum 2 g / L and 5 g / L.
On the other hand, under the condition (9): Kawamuro 10 g / L, the turbidity slowly increased from the start of the culture, became 29 degrees after 7 days, and a large amount of shiogusa was generated after 13 days, and the turbidity was also 50 degrees ( Phosphorus was clearly reduced, but the decrease in nitrogen was small after 6 days and conversely rose after 13 days).

b. Change over time in transplanted water culture In the second step, the condition (3) influent water alone had a maximum turbidity of 13 degrees after 13 days of culture, and the condition (12): Kawaturumo 10 g / L had a maximum turbidity of 34 days after the start of culture. It was time. Furthermore, in the third step in which nitrogen and phosphorus were added, the turbidity increased again. Condition (3): Inflow water alone was 11 degrees after 21 days of culture, Condition (12): Kawagurumo 10 g / L was started. It became 8 degrees after 20 days.
On the other hand, with respect to the above two conditions, almost no increase in turbidity is observed over the entire period of the culture test under the conditions (10): Kawagurumo 2 g / L and the conditions (11): 5 g / L. In the transplanted water culture in the second step, the condition (10): maximum turbidity is 4.5 degrees 9 days after the start of culturing at 2 g / L, and the condition (11): maximum at 5 days after culturing at 5 g / L. The turbidity is only 2.4 degrees. That is, even if nitrogen and phosphorus are added, or if influent water is added for the purpose of adding seed bacteria again, the turbidity hardly increases.

c. FIG. 5 is a graph showing the effect of the amount of kawaturum on co-culture in the influent water, and FIG. 6 is a graph showing the effect of the amount of kawaturum on the transplant water culture in the influent water. All graphs show the relationship between the amount of kawaturum and turbidity using the number of days of culture as a parameter.

  As shown in the graph of FIG. 5, it can be seen that under the condition (8) kawaturum 5 g / L, there is almost no increase in turbidity regardless of the number of days elapsed. Further, it can be seen that the increase in turbidity is small even under the condition (7) Kawaturumo 2 g / L, regardless of the elapsed days, compared with the condition (1) Kawaturumo 0 g / L.

  Further, as shown in the graph of FIG. 6, in the transplanted water culture, the turbidity hardly increased regardless of the elapsed days under the condition (10) kawaturum 2 g / L and the condition (11) kawaturum 5 g / L. From this, it is considered that during the 6 days of co-culture, some substances were secreted from the kawaturum, and the allelopathic activity of the secreted substances lowered the ability of the phytoplankton in the suspended state to proliferate. As described above, since this state lasted for at least 10 days (period of the second step), it is presumed that the turbidity increase can be suppressed for 10 days even in the transplanted water culture.

  The spilled water collected at the site is the water that flows into the pond A where the water flowing into the pond A has grown. The result of culturing the effluent as it was and further nitrogen added was as shown in FIG. 3 of the previous single culture, and the turbidity did not increase. This situation was the same even after 16 days of culture.

d. Life span of allelopathic activity by kawarumoru In the transplanted water culture in condition (10) kawaturumo 2 g / L and condition (11) kawaturumo 5 g / l, there is no increase in turbidity until 10 days after the start of culturing. In addition, there is no increase in turbidity after 16 days in culture of effluent alone. From this, it was found that the suspended phytoplankton lost its ability to grow due to the allelopathic activity of some substance secreted in the co-culture, and this state persisted for at least about 10 days.

e. Duration of allelopathic activity by kawaturum The series of studies did not confirm the duration of allelopathic activity. For this reason, apart from the above test, a new confirmation test was conducted in order to ascertain the number of days of allelopathic activity. Table 3 shows the quality of the influent water.

  The above condition (8): using a co-culture solution of 5 g / L kawaturum as transplantation water, b) culturing as transplantation water immediately after filtration, c) culturing after standing at 25 ° C. in the dark for 1 day, d) After filtration, each culture of 25 ° C. in a dark place for 7 days after static curing was performed, a turbidity test was performed, and the duration of allelopathic activity was evaluated. In addition, when performing transplantation water culture, it adjusted so that the nutrient salt in a solution might be 1 mg / L as D * TN and 0.5 mg / L as D * PO4-P. From the graph showing the relationship between the number of days elapsed and the turbidity in FIG. 7 as the test results, the condition (8): a solution co-cultured with 5 g / L of kawaturum is used as transplantation water, and b) when cultured as transplantation water immediately after filtration. c) In the case of culture after static curing at 25 ° C. in the dark at 25 ° C. after filtration, there was almost no difference between them, and a phytoplankton inhibitory effect was observed. d) In the case of transplanted water after stationary curing at 25 ° C in the dark for 7 days after filtration, a) Test results of influent culture alone, b) Incubation as transplanted water immediately after filtration, and c) In the dark at 25 ° C after filtration It was an intermediate value with the test result of the culture after static curing for 1 day.

---- Summary ---
In each of the above-mentioned tests, in order to clarify the allelopathic effect of the submerged plant Kawarumo, three types of pond water were used: the inflow water to the A pond, the outflow water from the A pond, and the pond water of the B pond. Each test of culture, co-culture of kawaturum and pond water, and transplanted water culture of kawaturum and pond water was carried out. The main results regarding influent and effluent are as follows.

  1) In the independent culture of influent water (condition (1)), the turbidity increased from 2 days after the start of the culture and reached a maximum of 28 degrees after 4 days. At that time, both nitrogen and phosphorus decreased. In contrast, in the single culture of the effluent as it is (condition (2)) and further with nitrogen added (condition (3)), the turbidity does not increase even after 16 days from the start of the culture. Phosphorus did not change.

  2) In co-culture of influent and Kawatsurumo 2g / L (condition (7)), or Kawatsurumo 5g / L (condition (8)), both nitrogen and phosphorus decreased, but turbidity was 2g / L (condition) (7)) and 11 to 15 degrees, and Kawagurumo 5 g / L (condition (8)). Thus, the increase in turbidity was suppressed in the co-culture of kawaturum 2 g / L (condition (7)) and kawaturum 5 g / L (condition (8)).

3) Inhibiting the growth of phytoplankton, in addition to the allelopathic effect, influences such as light quantity inhibition, NP absorption competition, and zooplankton ingestion damage. Excluding these factors, in order to clarify the allelopathic effect, the filtrate was collected after 6 days of co-culture, mixed with the same amount of influent water again, and transplanted water culture was performed.
There was almost no increase in turbidity from the beginning of the culture to 10 days after the transplanted water culture of the influent water and the kawaturum 2 g / L (condition (10)) or the kawaturum 5 g / L (condition (11)). From these results, it can be said that the planting density of kawarumo is preferably 2 g / L to 5 g / L.

  4) From the results of co-culture and transplanted water culture, "In Kawagurumo 2g / L and 5g / L, some substances are secreted from kawaturum during 6 days of co-culture, and due to the allelopathic activity of these secreted substances, suspended plants It was interpreted that the plankton's ability to grow was low, and that the state persisted for at least 10 days, resulting in "almost no increase in turbidity in transplanted water culture". This interpretation is also supported by the fact that the turbidity did not increase in the previous culture of effluent alone.

  5) In the transplanted water culture test, the culture test was conducted up to 21 days, and after 16 days of culture, 1 ppm of D • TN and 0.5 ppm of D • PO4-P were added. The matters to be noted in that case are as follows. In the case where some allelopathic effect was observed by 16 days after the cultivation, no increase in turbidity was observed.

  6) In co-culture of the influent water and Kawagurumo 10g / L (condition (9)), the results were significantly different from those of Kawagurumo 2g / L and Kawaturumo 5g / L. In this case, the turbidity reached about 50 ° C., and the decrease in nitrogen after 6 days from the start of culture was small. On the contrary, it increased after 13 days from the start of culture, and increased to 2 ppm after 22 days.

  As mentioned above, according to this embodiment, generation | occurrence | production of algae can be suppressed efficiently, without requiring complicated management and a great cost.

  Although the embodiment of the present invention has been specifically described based on the embodiment, the present invention is not limited to this, and various modifications can be made without departing from the scope of the invention.

DESCRIPTION OF SYMBOLS 1 Water body (to suppress the generation of algae) 2 Bottom of the water 3 Submerged plant (having an allelopathic effect) 10 Bottom mud 15 Tank 11 Sand (covered sand)
20 Liquid, algae inhibitor (containing allelopathic substances derived from submerged plants)

Claims (3)

An algal control method characterized by planting a kawaturum having an allelopathic effect on the bottom of a closed water area where new water does not flow, which is a target of algae control, with a planting density adjusted to 2 to 5 g / L. . Algae suppression, characterized by adjusting the planting density of 2-5 g / L of the kawaturum having an allelopathic effect and injecting a culture solution obtained by culturing for 6 days or more into a water area to be controlled by algae Method. An algal inhibitor characterized by being a culture solution obtained by adjusting a planting density to 2 to 5 g / L and cultivating kawaturmo having an allelopathic effect for 6 days or more .

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