Research Topics

“Water” is essential for our lives and livelihoods, and also works as a medium of transporting substances on both local and global scales. Therefore, the sustainability of our life and ecosystem can be easily threatened by the excess usage and pollution of water resources.
We are doing education and researches on “water quality control technology (water treatment)” and “relationship between material transport and aquatic ecosystems” to solve or prevent such issues for water resources. We hope to make our society safe, comfortable, and sustainable.

Wastewater to food production: A new wastewater treatment process

In the future world with more increased population, we will need more food and fertilizer. But, fertilizer reserve is limited, and the fertilizer production causes environmental pollution. Wastewater from increased population will be an another environmental issue. To protect the environment and supply enough food for our children, we have been developing a new wastewater treatment process not only to treat the wastewater but also recover nutrients for fertilizer. More than that, we have been trying to increase the value of the recovered products using microalgae. This microalgae produces astaxanthin, a high value antioxidative red pigment. The pigment can be used as an supplement or an ingredient of fish feed. Our goal is to establish a society in which wastewater treatment is economically beneficial, and resources in wastewater are recovered and recycled for sustainable food production.

Evaluation of the groundwater function for conservation of coastal ecosystems

Seagrass and seaweed meadows are regarded as an important coastal ecosystem for their functions of “ecosystem service”, such as carbon stock and habitats. Though conservation of these meadows is a global issue for the healthy cycles of food and materials, their biomass has been decreasing worldwide. Diversity in the coastal environment (e.g. variation in salinity, water temperature, nutrients, bottom materials etc.), produced by both sea-factors and terrestrial-factors, is important for seagrass and seaweed meadows to coexist with the other primary producers. We will evaluate the function of “submarine groundwater discharge (SGD)” for diversity production in the coastal environment by field observations, satellite data, and hydrological models. The results of this work will provide new scientific insights for material cycles in coastal areas. This work will also contribute to the conservation measures of seagrass and seaweed meadows, and associated coastal ecosystems through the development of future strategies based on the groundwater management in terrestrial areas.

Publication List

• Nagare, H., Nomura, Y., Nakanishi, K., Akao, S. and Fujiwara, T.: Characterization of Effluent Water Quality from Hydroponic Cultivation System, J. Water Environ. Technol. Vol. 19, No. 2, pp. 64-73, 2021.
• Nagare, H., Iwata, T., Ebi, A., Akao, S., Maeda, M., Yasutake, D. and Fujiwara, T.: Simultaneous recovery of phosphorus and potassium from biomass as magnesium salt, 土木学会論文集G（環境）. Vol. 76, No. 7, pp. III_181-III_187, 2020.
• Akao, S., Yasutake, D., Kondo, K., Nagare, H., Maeda, M. and Fujiwara, T.: Effects of cultivation period on catch crop chemical composition and potential for bioenergy production, Industrial Crops and Products. Vol. 111, No. 787-793, 2018.
• 永禮英明, 渡辺諒, 藤原拓, 赤尾聡史 and 前田守弘: 大型水生植物からのリン回収, 土木学会論文集G（環境）. Vol. 72, No. 8, pp. III_249-III_254, 2016.
• Sato, H., Nagare, H., Huynh, T. N. and Komatsu, H.: Development of a new wastewater treatment process for resource recovery of carotenoids, Wat Sci Tech. Vol. 72, No. 7, pp. 1191-1197, 2015.
• Saito, M., Okuda, N. & Onodera, S. I., Material transport and cycle in watersheds: toward the interdisciplinary collaboration between limnology and the other research disciplines, Limnology, 21(3), 427-428, 2020.
• Ye, Z., Chen, J., Gao, L., Liang, Z., Li, S., Li, R., Jin, G., Shimizu, Y., Onodera, S. I., Saito, M. & Gopalakrishnan, G., 210Pb dating to investigate the historical variations and identification of different sources of heavy metal pollution in sediments of the Pearl River Estuary, Southern China, Marine Pollution Bulletin, 150, https://doi.org/10.1016/j.marpolbul.2019.110670 , 2020.
• Zhu, A., Saito, M., Onodera, S. I., Shimizu, Y., Jin, G., Ohta, T. & Chen, J., Evaluation of the spatial distribution of submarine groundwater discharge in a small island scale using the 222Rn tracer method and comparative modeling, Marine Chemistry, 209(11), 25-35, 2019.
• Saito, M., Onodera, S. I., Jin, G., Shimizu, Y. & Taniguchi, M., Nitrogen dynamics in a highly urbanized coastal area of western Japan: impact of sewage-derived loads, Progress in Earth and Planetary Science, 5(1), https://doi.org/10.1186/s40645-018-0177-6 , 2018.
• Saito, M., Onodera, S., Okubo, K., Takagi, S., Maruyama, Y., Jin, G. & Shimizu, Y., Effects of physical and morphometric factors on nutrient removal properties in agricultural ponds, Water Science and Technology, 72(12), 2187-2193, 2015.

Related Link

• HP URL：Water Environment and Sanitation[New window]