Posted November 14, 2017 by Rino Rakhmata Mukti, Dr. rer.nat in Guest Seminar

Water environmental remediation techniques for removal of pollutants and Water environmenttrol of algal blooms in eutrophic freshwater systems

Prof. Takayoshi Hara
Chiba University, Department of Applied Chemistry and Biotechnology, Japan

Eutrophication is caused by large amount of nutrient input (mainly nitrogen and phosphorus) accompanying population growth, urbanization, and industrialization. In eutrophic freshwater systems such as lakes, algal blooms appear in summer, causing various water environmental issues. In our laboratory, we have aimed to reduce the degree of eutrophication and to suppress algal blooms by several approaches based on laboratory and field experiments.
For the reduction of the degree of eutrophication, we have attempted to prepare high-performance activated carbons for removal of nitrate and phosphate ions, and organic pollutants and cationic ions as well. We prepared original activated carbons possessing different pore structures and surface functional groups by applying chemical and physical activation methods, outgassing, and oxidation treatments, and revealed that the removal of anionic ions (nitrate and phosphate ions), organic pollutants (dyes), and cationic ions (heavy metals) were strongly attributed to basic sites, mesopores, and acidic functional groups on the activated carbons, respectively.
We have also examined the effective way for the control of algal blooms. A typical bloom-forming cyanobacterium Microcystis produces extracellular polysaccharides (EPS), and forms colony by being covered with EPS. Because of its less gravity than water, Microcystis can rise up to the water surface by expanding colony size (stokes’ low). Based on the hypothesis that Microcystis would effectively rise up by increasing EPS production, promoting colony formation, and expanding colony size, we isolated EPS from cyanobacterial blooms, and added EPS into algal blooms samples to increase the amount of EPS in the solution. The results indicated that the size of Microcystis colonies was enlarged by adding EPS, and that Microcystis cells could effectively be separated by lake water accompanying enhanced floating velocity.

Selected papers
D. Jiang, Y. Amano, M. Machida, Environ. Sci. Pollut. Res., 24, 8210-8218 (2017).
T. Goto, R. Dolphen, Y. Amano, P. Thiravetyan, M. Machida, Desalin. Water Treat., 59, 287-294 (2017).
M. Sato, K. Omori, T. Datta, Y. Amano, M. Machida, Environ. Eng. Sci., 34, 149-157 (2017).