Development of Suppression and Reduction System for Toxic Cyanobacteria in Asia Pacific Region

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In this study, suppressing effect to harmful cyanobacteria, such as Microcystis by hybrid system which has combined channel planting hydrophyte for removal of nutrients and bioreactor fixing predacious microanimals was examined on experiment pond in Thailand. The fibroid carrier produced with waste plastic which had become unused in the locale was filled to the bioreactor, and Puckboong as eatable hydrophyte had been planted to the channel. The removal ability of toxic Microcystis was examined for a long term by this hybrid system, as a result the bioreactor achieved removal ratio more than 95%. Microanimal almost not detected on the experiment pond was gathered with high dense to the surface of carrier in bioreactor, and a lot of the microanimal community preying on Microcystis was observed. There is a possibility that microcystin remains in the bioreactor after the microanimal preys on Microcystis. As a result of the analysis that used high price performance liquid chromatography (HPLC), microcystin was not detected from outflow water of the bioreactor. This result suggests having the ability to produce enzymes by which either the microanimal or the bacteria in the bioreactor decomposes microcystin. The safety of hydrophyte as for food has improved because microcystin was completely decomposed though outflow water of the bioreactor enters the channel. The average removal ratio of nitrate-nitrogen and ammonium-nitrogen in the channel was 40% and 30% respectively. Moreover, a part of Puckboong that grew up was able to be harvested from the channel once about two weeks. Proper management to remove the nutrient from the pond water became possible by taking out Puckboong that grew up from the channel. In addition, the main material of this hybrid system confirmed obtaining was easy in Thailand.