JP2014187962A - Water quality testing method using algae - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water quality testing method using algae for simply and accurately determining water quality of environmental water, treated factory wastewater, culture solution of algae, or the like.SOLUTION: Water to be tested is irradiated with white light from a light-emitting section 2 of a transmission color sensor 1, a light receiving section 3 receives light transmitted through culture solution 4, a color filter (not shown) decomposes the received light and detects green light (500 to 570 nm) and red light (620 to 740nm), absorbance of each color is calculated from a light intensity of the green light and a light intensity of the red light, a culture state of algae is determined based on a ratio (absorbance ratio) of the light intensities, algal growth potential (AGP) or growth inhibition property of the algae in water to be tested is determined by comparing with a reference absorbance ratio of environmental water or the like.

Description

  The present invention relates to a water quality test method using algae for judging the water quality of environmental water, industrial wastewater treated water, or algae culture solution.

  Environmental water such as rivers, lakes, and seawater is not preferable in an environment where microalgae such as blue-green algae can easily propagate. Also, treated water that has been treated from factory wastewater should not be allowed to be discharged to the outside environment with water quality that adversely affects the environment. For example, even highly treated water is often richer in nutrient salts such as nitrogen and phosphorus than in general water, and there is a risk that the growth of microalgae may be promoted. In general, therefore, environmental water and factory wastewater are collected and analyzed for water quality, and the contents of pH, various heavy metals, organic carbon components, total nitrogen (TN) and phosphorus are analyzed. However, there has been a problem that the results of the analysis of these various components cannot necessarily be an accurate indicator of the influence on the environment such as treated water.

  In addition, microalgae are used for industrial purposes and are grown in a culture solution for industrial use. To make this culture solution suitable for growth, fertilizer components can be added to environmental water. doing. However, the current situation is that it is not possible to determine whether the culture solution is suitable for culturing actual algae without culturing the algae.

  This is because there are many kinds of harmful substances and growth promoting factors in environmental water, and it is not realistic to analyze all of these components individually. On the other hand, it is possible to evaluate the water quality by biological tests as the sum of the chronic effects on living organisms.

  Therefore, various biological test methods for actually culturing algae and judging the water quality based on the results have been performed. For example, as a biotoxicity test, there is an AGP test method which is one of sewer test methods. Here, AGP is an abbreviation for Algal Ground Potentials. In this AGP test method, algae is inoculated into the effluent water (treated water), and this is maintained in a predetermined condition, and the degree of growth is determined in the effluent water area. By comparing it with that of, the effect of this effluent on eutrophication in the effluent area is evaluated.

  The National Institute for Environmental Studies has developed an algae growth inhibition test. This algae growth inhibition test is required for notification of new chemical substances. By exposing algae to test substances (environmental water and treated water) and comparing the growth inhibition rate with the discharge water area, It reveals the toxicity of the test substance to growth.

  In these methods, algae are measured by dry weight method, particle measurement method, absorbance method, chlorophyll method, direct measurement method and the like.

  These AGP test and algal growth inhibition test are both objectively reliable. However, these test methods have the following various problems. In other words, the dry weight method requires a certain amount of test period, but it is necessary to collect and keep analyzing the culture solution over time for analysis, so a large amount of test substances (environmental water and treated water) and culture Not only is liquid required, but the operation of concentration measurement is complicated. Further, the particle measurement method, the absorbance method, and the chlorophyll method are not versatile because they require very expensive measuring instruments. Further, the direct measurement method is likely to cause measurement errors because the measurement accuracy depends on the skill level of the measurer. Thus, although it is possible to evaluate water quality by biological tests, there has been no conventional method for accurately performing water quality.

  The present invention has been made in view of the above problems, and provides a water quality test method using algae for easily and accurately judging the water quality of environmental water, industrial wastewater treated water, or algae culture solution. With the goal.

  In order to solve the above-described problems, the present invention adds algae to water to be tested, and changes the color of water to be tested containing the algae to blue light (450 to 490 nm), green light (500 to 570 nm) and red light ( 620 to 740 nm) to detect at least two or more wavelength ranges, and determine the algae productivity (AGP) or growth inhibition of the algae based on the light intensity of these two or more light wavelengths. Provided is a water quality test method utilizing algae (Invention 1).

  According to this invention (Invention 1), in order to decompose the color of water to be tested containing algae into blue light, green light and red light, the chromaticity of visible light may be detected separately for RGB, and it is inexpensive. A color sensor can be applied. By applying the color sensor, online measurement is possible, and the measurement time can be greatly shortened and the measurement can be simplified. Furthermore, this color sensor can detect a wide range of color tone changes such as satellite photographs with only visible light. Thus, it is possible to determine the algae productivity (AGP) or the algae growth inhibitory property of the water under test by efficiently monitoring the culture state of the algae and comparing it with the standard environmental water or the like. .

  In the said invention (invention 1), the said green light (500-570 nm) and the said red light (620-740 nm) are decomposed | disassembled and detected, The light intensity of the wavelength of the said green light, and the light intensity of the wavelength of red light From these, it is preferable to determine the algae productivity (AGP) or the growth inhibition of algae (Invention 2). The absorbance of the green light is calculated from the light intensity of the green light wavelength, the absorbance of the red light is calculated from the light intensity of the red light wavelength, and the red light absorbance is divided by the absorbance of the green light. It is preferable to determine the algal productivity (AGP) of the test water or the growth inhibition of the algae (Invention 3).

  According to such inventions (Inventions 2 and 3), the intensity ratio between the absorbance of red light and the absorbance of green light is correlated with the culture rate of green algae performing photosynthesis, and the absorbance ratio increases as the culture rate increases. Therefore, it is possible to determine the algae productivity (AGP) or the growth inhibition of algae by comparing with the absorbance ratio of the environmental water or the like as a reference.

  In the said invention (invention 1-3), the spectrum of the water to be tested is compared by comparing the light intensity of each wavelength obtained by spectroscopy of the water under test containing the algae with the light intensity of each wavelength obtained by separating white light. It is preferable to calculate the absorbance of each wavelength and determine the algae productivity (AGP) or growth inhibition of the algae based on the absorbance of each light (Invention 4). In the said invention (invention 3), it is preferable that the said white light is the reflected light from the white substance which permeate | transmitted the clear water or the clear water (invention 5).

  According to the inventions (Inventions 4 and 5), the blue light, green light and red light intensity of water to be tested containing algae is compared with the light intensity of each wavelength obtained by spectrally dividing white light. By calculating the absorbance, it is possible to accurately determine the algal productivity (AGP) of the water to be tested or the growth inhibition of the algae.

  According to the present invention, the color of the water to be tested containing algae is detected by decomposing it into blue light, green light and red light, and the culture state of the algae is determined by comparing the light intensity of the band light of these wavelengths. Therefore, it is possible to measure the culture state of the algae on-line, and the measurement time can be greatly shortened and the measurement can be simplified. By this, the culture state of algae is efficiently monitored, and the algae productivity (AGP) or the growth inhibition of algae is determined by comparing with the standard absorbance ratio of environmental water, etc. Can do.

  In particular, the color of the water under test containing algae is detected by decomposing green light and red light, and the red light absorbance is determined from the light intensity of the band light of the green light wavelength and the light intensity of the band light of the red light wavelength. The absorbance of green light is determined, the value obtained by dividing the absorbance of red light by the absorbance of green light (absorbance ratio) is calculated, and the algae productivity (AGP) of the test water of the algae is calculated from the value of this absorbance ratio. Or it becomes possible to determine the growth inhibitory property of algae.

It is the schematic which shows the apparatus which can implement the water quality test method using the algae concerning 1st embodiment of this invention. It is the schematic which shows the apparatus which can implement the water quality test method using the algae concerning 2nd embodiment of this invention. It is a graph which shows the relationship between the light absorbency in the water quality test method using the algae in Example 2, and a specific growth rate.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, this embodiment is only an example, and the present invention is not limited to this.

  In this embodiment, algae that have been cultured in advance are added to the water to be tested, and the color of the water to be tested containing the algae is changed to blue light (450 to 490 nm), green light (500 to 570 nm), and red light ( 620 to 740 nm) to detect at least two or more wavelength ranges, and determine the algae productivity (AGP) or growth inhibition of the algae based on the light intensity of these two or more light wavelengths. To do.

  Specifically, in the case of green algae performing photosynthesis, the green light (500-570 nm) and the red light (620-740 nm) are decomposed and detected from the color (chromaticity) of the culture solution containing algae, The algae productivity (AGP) of the water to be tested or the growth inhibition of algae is determined from the light intensity in the wavelength range of the green light and the light intensity in the wavelength range of the red light.

  In the present embodiment, the water to be tested is not particularly limited, and environmental water such as rivers, lakes, and seawater, treated water that has been processed from factory wastewater, and culture solution for using algae for industrial purposes are tested. can do. In the water to be tested as described above, pretreatment such as filtration, pyrolysis and dilution can be performed, or fertilizer components such as nitrogen and phosphorus can be added depending on the purpose of evaluation.

  Common algae, microalgae, cyanobacteria, and the like can be used as the algae inoculated into the test water, and microalgae are particularly preferable. Specifically, when the water to be tested is fresh water, Selenastrum capricornutum, Chlorella ellipsisidea, Chlorella vulgaris, Microcystis aeruginosa, f. aeruginosa Microcystis aeruginosa f. flosaquae, Stigeoclonium tenue, Anabaena flosaquae, Chlamydomonas sp, Cyclotella genus, Nitzschia sp, Synedra genus, Nitzschia Palea, and Pseudokirchneriella subcapitata (Korshikov) but such F.Hindak is preferred, but is not limited thereto.

  Moreover, when test water is seawater, Skeletonema costatum, Thalassiosira pseudona, Chattonella antique, Dunaliella teriolecta, and Heterosigma genus can be preferably used.

  These algae are preferably cultured in advance (preculture) in a necessary amount.

  When the algae is inoculated into the test water, it is cultured. The culture with the water to be tested is preferably performed at a temperature of 20 ± 2 ° C. or 25 ± 2 ° C., and a temperature adjusting mechanism may be provided in the culture tank for that purpose. Moreover, it is preferable to irradiate the algae with light in the range of illuminance of 1,000 to 4,000 lux, and a mechanism capable of adjusting the light amount within the above range is provided. Furthermore, it is preferable to culture while stirring and mixing the culture solution. For this reason, a shaking mechanism or an aeration mechanism is required.

  When the algae inoculated in this way are cultured in the test water for a predetermined period, the chromaticity of the cultured water to be tested is detected. As a means for detecting the chromaticity of the water under test, it is preferable to use a color sensor because it is inexpensive and can separately detect green light, red light and blue light. This color sensor has a mechanism in which measured colors are separated into RGB components by a color filter, and the light intensity of each color component is detected by a photo diode or the like. This color sensor can detect changes in a wide range of color tones such as satellite photographs using only visible light.

  Specifically, the color sensor is used to determine the algae culture state (growth rate) as follows. That is, first, white light is irradiated to transparent water (for example, pure water) that does not absorb light, and the transmitted light is detected by a color sensor. Since this white light is decomposed into RGB components by the color filter of the color sensor and received, the respective light intensities of the red band light (green light) R1 and the green band light (green light) G1 are measured. To do.

  Next, the test water in which the algae is cultured is irradiated with white light in the same manner using the same color sensor, and the transmitted light is detected by the color sensor. Since this transmitted light is separated into RGB components by the color filter of the color sensor and received, the respective light intensities of the red band light (red light) R2 and the green band light (green light) G2 are measured. To do.

  The red band light (red light) and the green band light (green light) can be measured using, for example, a transmissive color sensor 1 as shown in FIG. 1 described in Japanese Patent Application Laid-Open No. 2010-151605. it can. The transmissive color sensor 1 includes a light emitting unit 2 and a light receiving unit 3 including a color filter (not shown), and irradiates white light from the light emitting unit 2 and transmits light transmitted through the culture solution 4. Light is received by the light receiving unit 3, and the light intensity of each of the red band light (green light) and the green band light (green light) is calculated by a control mechanism (not shown).

  A reflective color sensor 11 as shown in FIG. 2 described in JP 2010-181150 can also be used. The reflective color sensor 11 includes a light receiving unit 13 including a light emitting unit 12 and a color filter (not shown), and a reflective plate 14. The reflective color sensor 11 irradiates white light from the light emitting unit 12, and The light that has passed through the culture medium 15 is received by the light receiving unit 13, and the light intensity of each of the red band light (green light) and the green band light (green light) is calculated by a control mechanism (not shown).

In this way, when the red light and green light absorption intensities of the water to be tested containing transparent water and microalgae are measured, the red light absorbance and green light absorbance and the ratio (absorbance ratio) of the two according to the following formula Are calculated respectively.
Red band light absorbance: A _R = −log (R2 / R1)
Green band light absorbance: A _G = −log (G2 / G1)
Absorbance ratio: X = _AR / _AG

On the other hand, the weight concentration of microalgae in the water to be tested is measured, and the specific growth rate is measured. This specific growth rate is obtained, for example, by measuring the weight of a suspended substance in a culture solution with a glass fiber filter having a pore diameter of 1 μm and measuring the weight thereof, and calculating the weight concentration from the amount of the culture solution (test water). Then, the weight concentration C1 [mg / L] and the amount of culture solution V1 [L] at the culture day T1 [day], and the weight concentration C2 [mg / L] and the culture solution amount at the culture day T2 [day]. The specific growth rate ν [1 / day] is calculated from V2 [L] by the following formula.
Specific growth rate: ν = (ln (m2 / m1)) / (T2-T1) (1)
(In Formula (1), m1 = C1 × V1, m2 = C2 × V2)

  According to the study of the present inventor, it was found that a high correlation was observed between the specific growth rate (ν) and the absorbance ratio (X). As a result of analyzing this correlation, it can be determined that the specific growth rate (ν) decreases when the absorbance ratio (X) decreases, and the algal growth inhibition is large. On the other hand, the specific growth rate when the absorbance ratio (X) increases. It can be judged that (ν) decreases and the algal productivity is large. Therefore, for example, in the case of treated water of factory wastewater, the algae is cultured in advance in the water of the discharge water area, the absorbance ratio (X) is measured, and compared with this, the treated water of the factory wastewater is What is necessary is just to judge whether it shows the increase tendency of productivity or the increase tendency of the growth inhibitory property of algae. In the case of a new culture solution, the algae is cultured in advance with a reference culture solution, and the absorbance ratio (X) is measured. It is sufficient to determine whether or not it shows a tendency to increase or a growth inhibition of algae.

  Furthermore, if this correlation is applied, the treatment conditions will be changed in the case of treated water of factory effluent, or the components will be changed in the case of a culture solution so that the absorbance ratio (X) will have a desired tendency. You may make it take the measures.

  As mentioned above, although this invention has been demonstrated based on the said embodiment, this invention is not restricted to the said embodiment, A various change implementation is possible. For example, in the present embodiment, for green microalgae, the culture state of microalgae is determined based on green light (500 to 570 nm) and red light (620 to 740 nm). In the case of red microalgae, absorbance data of blue light (450 to 490 nm) can be used.

The present invention will be described in more detail based on the following specific examples and comparative examples, but the present invention is not limited to the following examples.
Example 1

Using an AAP medium having the composition shown in Table 1 adjusted to pH 7.5 ± 0.1 Chlorella vulgaris Beijerinck (NIES-2170 strain: hereinafter referred to as test strain 1) distributed from the National Institute for Environmental Studies microbial strain preservation facility, Place this AAP medium in a 1 L glass flat culture bottle, add industrial CO ₂ at a concentration of 3% by volume, ventilate, and illuminate with fluorescent lamp (light / dark = 12 hr / 12 hr, illuminance 4000 lux) For 7 days.

  Then, the test strain 1 that has been precultured and collected by centrifugation (1,000 G, 5 minutes) is added to a sterilized sodium hydrogen carbonate solution (15 mg / L), shaken, and sufficiently suspended. After that, it was centrifuged again to collect algal bodies. AAP medium (condition 1; reference condition) using the collected algal cells of test strain 1 as simulated water for test water, AAP medium (condition 2) with a sodium nitrate concentration increased to 400 mg / L, and hypochlorous acid AAP medium (condition 3) supplemented with 0.1 mg / L of sodium was inoculated so as to have an algal body concentration of about 0.4 g / L, respectively, and cultured in a 1 L glass flat culture bottle. . Condition 1 was assumed to be a standard condition, condition 2 was a condition simulating water with high algal productivity, and condition 3 was a condition simulating water having an algal growth inhibitory property.

Culturing was carried out for 14 days under a fluorescent lamp illumination (bright / dark = 12 hr / 12 hr, illuminance 4000 lux), aerated with industrial CO ₂ added to a concentration of 3% by volume, as in the pre-culture described above. The culture solution (test water) of this test strain 1 was irradiated with white light, and the transmitted light was measured using a detector equipped with the photosensor shown in FIGS. The optical sensor received light through three color filters of RGB, and measured the light intensity of each of the red band light R2 and the green band light G2.

  On the other hand, the pure water produced by the pure water production apparatus WG270 manufactured by Yamato Kagaku Co., Ltd. is transparent water that does not absorb light, the pure water is irradiated with white light, and the transmitted light is similarly detected by the detector. . Similarly, the light intensities of the red band light R1 and the green band light G1 were measured, and the absorbance and the absorbance ratio were calculated by the following equations.

Red band light absorbance: A _R = −log ₁₀ (R2 / R1)
Green band light absorbance: A _G = −log ₁₀ (G2 / G1)
Absorbance ratio: X = _AR / _AG

  At the same time, the weight concentration of test strain 1 in the culture solution was measured, and the specific growth rate was calculated by the following equation. The specific growth rate was calculated by measuring the weight by filtering the suspended matter in the culture solution with a glass fiber filter having a pore size of 1 μm and calculating the weight concentration. Then, the weight concentration C1 [mg / L] and the amount of culture solution V1 [L] at the culture day T1 [day], and the weight concentration C2 [mg / L] and the culture solution amount at the culture day T2 [day]. The specific growth rate ν [1 / day] was calculated from V2 [L] by the following formula. Table 2 shows the measurement results of the absorbance ratio X and specific growth rate ν of red band light and green band light under conditions 1, 2 and 3.

Specific growth rate: ν = (ln (m2 / m1)) / (T2-T1) (1)
(In Formula (1), m1 = C1 × V1, m2 = C2 × V2)

As apparent from Table 2, there is a correlation between the absorbance ratio X of the red band light and the green band light and the specific growth rate ν, and the algal productivity of the water to be tested is higher than that of the condition 1 as a reference. The value of the absorbance ratio X increases (Condition 2), and if the water under test has a high algal growth inhibitory property, the value of the absorbance ratio X tends to decrease (Condition 3). It was confirmed that it can be an index for judging the algal productivity and algae growth inhibition of water.
(Example 2)

Desmodesmus sp. Sold by the National Institute for Environmental Studies microbial strain preservation facility. (NIES-96 strain) was adjusted to pH 6.5 to 7.5, and C medium having the composition shown in Table 3 and Table 4 was used. Industrial CO ₂ was added to C medium at a concentration of 3% by volume. The material was aerated and cultured with fluorescent lamp illumination (bright / dark = 12 hr / 12 hr). The culture solution was subjected to half-batch culture under the four conditions shown in Table 5, and the change over time in the absorbance ratio X of the red band light and the green band light and the specific growth rate ν was calculated in the same manner as in Example 1. The results are shown in FIG.

  As shown in FIG. 3, a high correlation was observed between the absorbance ratio X and the specific growth rate ν, and it was confirmed that the absorbance ratio X can serve as an index for determining the algal productivity and algal growth inhibition of the water to be tested.

  According to the water quality test method using algae as described above, the color of water under test containing algae is detected by decomposing into blue light, green light and red light, and the absorbance ratio is determined from the light intensity in these wavelength regions. Calculated and compared with the absorbance ratio of environmental water, etc., as a reference, and the algae productivity (AGP) or growth inhibition of the algae is determined by the water under test, so an inexpensive detection device such as a color sensor Thus, the productivity and growth inhibition of algae can be determined with good reproducibility. In particular, since a color sensor can be used, it is possible to provide a water quality test method having high stability without being influenced by the proficiency level of the measurer.

DESCRIPTION OF SYMBOLS 1 ... Transmission type color sensor 2 ... Light-emitting part 3 ... Light-receiving part 4 ... Culture solution 11 ... Reflection type color sensor 12 ... Light-emitting part 13 ... Light-receiving part 14 ... Reflecting plate 15 ... Culture solution

Claims (5)

Add algae to the water under test,
The color of water to be tested containing algae is decomposed into blue light (450 to 490 nm), green light (500 to 570 nm) and red light (620 to 740 nm), respectively, and at least two wavelength ranges are detected.
A water quality test method using algae, wherein the algae productivity (AGP) of the water to be tested or the growth inhibition of algae is determined based on the light intensity of the wavelength of two or more light.   The green light (500 to 570 nm) and the red light (620 to 740 nm) are decomposed and detected, and algae is produced from the light intensity of the green light wavelength and the light intensity of the red light wavelength. The water quality test method using algae according to claim 1, wherein force (AGP) or growth inhibition of algae is determined.   The absorbance of the green light is calculated from the light intensity of the green light wavelength, the absorbance of the red light is calculated from the light intensity of the red light wavelength, and the red light absorbance is divided by the absorbance of the green light. The water quality test method using algae according to claim 2, wherein the algae productivity (AGP) or growth inhibition of algae is determined.   By comparing the light intensity of each wavelength obtained by spectroscopy of the test water containing the algae with the light intensity of each wavelength obtained by separating white light, the absorbance of each wavelength obtained by spectroscopy of the test water was calculated. The water quality test method using algae according to any one of claims 1 to 3, wherein algae productivity (AGP) or growth inhibition of algae is determined based on light absorbance.   5. The water quality test method using algae according to claim 4, wherein the white light is white light transmitted through clear water or reflected light from a white substance immersed in clear water.

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