• Korean Journal of Environmental Biology
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• v.21 no.2
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• pp.216-221
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• 2003

Various physico-chemical and biological methods have been used to remove. cyanobacteria which causes blooms and releases toxin. The purpose of the following experiment is aimed finding out which cyanobacteria are affected by $_L-lysine $ and what concentration of$_L-lysine $ inhibits cyanobacteria. The 20 samples of Microcystis sp. have been tested. To prove the growth inhibition on Microcystis sp., double-layered agar method and microplate method have been used. When the concentration of $_L-lysine $ is as heavy as 100 ${\mu}g\; ml^{-1}$~300 ${\mu}g\; ml^{-1}$, some Microcystis sp. have made halo zone. Some Microcystis sp. have shown so high activity as to be inhibited in their growth by the $_{L}$-lysine of concentration 10 ${\mu}g\; ml^{-1}$ with microplate method. These activities are various in accordance with every species. In additions, the microplate method has been proven to be an easy way which examine the lytic activity on the species of algae.e.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.10
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• pp.556-560
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• 2017

This research carried out to evaluate the disadvantage of pre-chlorination and the effect of polyamine as coagulant aids for treating the blooming water with Microcystis sp.. Pre-chlorination on blooming water makes the colony of Microcystis sp. to the smaller size. Coagulation with polyamine advanced treatment efficiency not only turbidity but also particulate matters especially less then $5{\mu}m$ size for the blooming water compared with using alum alone. Particle count was more sensitive than turbidity on water quality management of settlement and filtrate.

• Korean Journal of Environmental Biology
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• v.31 no.2
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• pp.113-120
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• 2013

This study aimed to investigate the effects of ultrasonic wave on colonial changes of Microcystis sp. causing water-bloom. The effects of frequency change and exposure time of ultrasonic wave on Microcystis sp. were also perceived by measuring the concentration of chlorophyll-a. The concentrations of chlorophyll-a showed a decreasing tendency in all experimental groups exposed to ultrasonic waves, especially the highest decrease at 70 kHz. Before exposed to ultrasonic wave, single cells of Microcystis sp. were observed in a form of colonies which were densely accumulated onto their mucilage layer. However, after one hour exposure to 70 kHz ultrasonic wave, the bonds of colonies were weakened and single cells were separated from the colonies. Moreover, the single cells of the colony were destroyed with the 5 hour exposure time at 70 kHz. As a result, we proposed that the frequency strength and the exposure time of ultrasonic wave might have effects in decrease of biomass of blue-green algae by reducing the concentration of chlorophyll-a, thereby changing and destroying forms of Microcystis sp. colonies.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.5
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• pp.351-358
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• 2012

Formation of disinfection by-products (DBPs) including trihalomethans (THM), haloacetic acid (HAA) and haloacetonitriles (HAN) from chlorination of extracellular organic matter (EOM) and cells + intracellular organic matter (IOM) of Microcystis sp., a blue-green algae, during decomposed period was investigated. Microcystis sp. cells + IOM and EOM of Microcystis sp. exhibited a high potential for DBP formation. HAAFP (formation potential) was higher than THMFP during decomposed period. In the variations of HAAFP species during decomposed period, the ratio of di-HAAFP species was gradually decreased and the ratio of tri-HAAFP species was gradually increased in the case of EOM during decomposed period, while the opposite result was in the case of cells + IOM during decomposed period. In the variations of HANFP species during decomposed period, the ratio of di-HANFP species was much higher than the ratio of tri-HAAFP species.

• Journal of Korean Society on Water Environment
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• v.16 no.4
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• pp.479-490
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• 2000

This study investigated the removal characteristics, Microcystin decomposition and generation of by-products when aqueous Microcystis sp. is oxidized by ozone. The concentration of Microcystin (MC) in aqueous solution has been found by HPLC analysis to decrease continuously by ozonation after the initial, abrupt increase. The kinetic constant of the decomposition of MC-RR and -LR were 0.0596 and 0.0243, respectively. This means that removal efficiency of MC-RR by its oxidative decomposition is preferable compared with that of MC-LR. On the other hand, it has been found that the decomposition product, TOC, exhibits the continuous decrease in the concentration by further ozonation, while DOC and UV-254 increase temporarily until 10 minutes before the decrease. Furthermore, the GC/MSD analysis has revealed that the ozonation of Microcystis sp. for 100minutes affords five kinds of aldehydes, six kinds of alcohols, and trans-1, 2-dimethyl-cyclopropane.

• Korean Journal of Environmental Biology
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• v.25 no.2
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• pp.81-87
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• 2007

The removal of Microcystis aeruginosa and Chlorella zofingiensis by ceramic powder was investigated on the basis of both the particle size (under 0.05, 0.1, 1 mm) and the dosage (0.1, 1, $10\;g\;L^{-1}$) of the ceramic powder. The removal efficiencies of M. aeruginosa and C. zofingiensis were highest with a particle size of 0.05 mm and a dosage of $1\;g\;L^{-1}$ of the ceramic powder in laboratory experiment. $chlorophyll-{\alpha}$ concentrations decreased in both field and enclosure samples with a particle size of 0.05 mm and a dosage of $1\;g\;L^{-1}$ of ceramic powder, resulting in the removal efficiencies of 67 and 69%, respectively. Consequently, it was concluded that the ceramic powder could be used to control algal bloom by removing $chlorophyll-{\alpha}$ in eutrophic waters.

• Environmental Engineering Research
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• v.24 no.3
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• pp.397-403
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• 2019

Microcystis sp. is one of the most common harmful cyanobacteria that release toxic substances. Counting algal cells is often used for effective control of harmful algal blooms. However, Microcystis sp. is commonly observed as a colony, so counting individual cells is challenging, as it requires significant time and labor. It is urgent to develop an accurate, simple, and rapid method for counting algal cells for regulatory purposes, estimating the status of blooms, and practicing proper management of water resources. The flow cytometer and microscope (FlowCAM), which is a dynamic imaging particle analyzer, can provide a promising alternative for rapid and simple cell counting. However, there is no accurate method for counting individual cells within a Microcystis colony. Furthermore, cell counting based on two-dimensional images may yield inaccurate results and underestimate the number of algal cells in a colony. In this study, a three-dimensional cell counting approach using a novel model algorithm was developed for counting individual cells in a Microcystis colony using a FlowCAM. The developed model algorithm showed satisfactory performance for Microcystis sp. cell counting in water samples collected from two rivers, and can be used for algal management in fresh water systems.

• Journal of Environmental Science International
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• v.25 no.3
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• pp.425-438
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• 2016

This study carried out zeta potential measurements of the Microcystis sp. under various solutions condition and investigated the characteristics of Microcystis sp. through the size control of microbubbles to eliminate algae that causes problems in aquatic ecosystems and human activities. DAF process was adopted and several coagulants were used to remove the Microcystis sp. CCD Camera was used to measure and analyze the size of microbubble, and fluorescent microscope was used to observe the particle, algae species and community. Zeta potential behavior of the algae was analyzed by using ELS-Z. Lab-scale and pilot-scale experiments were conducted to test flotation process. Polyaluminium chloride(PAC) coagulant was used, and the removal efficiency of the algae was assessed through Chlorophyll-a analysis. In the Lab-scale experiment, 2.2 ppm, 11 ppm, 22 ppm, and 44 ppm of polyaluminium chloride was injected to coagulate the algae. The coagulated algae was floated by the microbubble. The microbubbles in the experiments were generated at a air pressure of 450 ~ 550 kPa. The microbubble size was controlled in $36{\mu}m$, $100{\mu}m$, and $200{\mu}m$, respectively by using different diffuser. The results of lab-scale experiments on flotation plant indicated that the average removal rate was about 90% or above for 11 ppm, 22 ppm, and 44 ppm of polyaluminium chloride. On the other hand, in the pilot-scale experiment, the removal efficiency was in the range of 85% to 95% in all dose ranges of polyalumium chloride and aluminium sulfate coagulants.

• Korean Journal of Ecology and Environment
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• v.36 no.2 s.103
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• pp.208-214
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• 2003

Four species of water fleas (Daphnia magna, Daphnia pulex, Daphnia galeata, and Moina macrocopa) were examined for the clarification of their reproduction with culture conditions. The reproduction tests of water flea by the culture conditions were carried out. For the comparison of the reproduction rate, five media (manure-soil medium, DIN medium, M4 medium, EPA medium, fertilizer medium) were applied to determine the best medium. Daphnia magna, Daphnia pulex, and Moina macrocopa were appeared the best reproduction in the manure-soil medium at $20^{\circ}C.$ The lifespan and young reproduction were better in manure-soil medium than the others. But Daphnia galeata was lived for 34 days in the fertilizer medium at $20^{\circ}C.$ The culture of Daphnia galeata was difficult to rear than the other species. In the current study, the microcystin of Microcystis sp. did not particularly affect on the survival of water fleas. But the lifespan was short and the reproduction rate was low. Therefore water flea have a preference for Scenedesmus sp. than Microcystis sp. On the condition of the feeding Scenedesmus sp., all examined water fleas appeared to have the longest lifespan and the most young water fleas produced at any medium and temperature as compared with the feeding the Microcystis sp. For the culture temperature, the lifespan was longer on $20^{\circ}C$ than $15^{\circ}C$.

• Korean Journal of Environmental Biology
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• v.31 no.4
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• pp.429-439
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• 2013

This study was conducted to identify the relationship between environmental factors and algal bloom, and provide information for efficient management based on the results of monitoring the environmental parameters and algal diversity in the Jundai reservoir from March 2011 to October 2013. Little change in the weather conditions was observed during the study period except for a slight decrease in rainfall. Concentration of TN and TP in the reservoir exceeded water quality standards for agriculture and significant correlation between algal growth and environmental factors was observed. Phytoplankton in Jundai reservoir included 6 classes, 40 genus, 62 species, and the phytoplankton abundance was in the range of $1.3{\times}10^4{\sim}2.8{\times}10^6$ cells $mL^{-1}$. The annual average of phytoplankton abundance and Chl-a gradually decreased as TN and TP concentrations decreased. Overall Anabaena sp., Oscillatoria sp., and Microcystis sp. were the dominant species in Jundai reservoir. As the water temperature increased, the dominant species were Anabaena sp., Microcystis sp. and Oscillatoria sp., in that order. Anabaena sp. was dominant from spring to early summer with increase in water temperature and pollutant concentrations, and high correlation with environmental factors was observed. Microcystis sp. was dominant depending on changes in the nutrient levels. In the case of Oscillatoria sp., there was no significant correlation between phytoplankton biomess and Chl-a. However, efficient management of water environment and practical control of algal bloom in small scale reservoir polluted by livestock and farm irrigation should be achieved by identification of the relationship between algal growth and environmental factors.