research content |
- Development of energy-saving wastewater treatment technology using the functions of photosynthetic microorganisms
Human activity and wastewater generation are inseparably linked, and proper treatment of wastewater is essential to prevent water pollution and the spread of epidemics. However, existing wastewater treatment technologies have been popularized mainly in developed countries with stable economic foundations and the ability to invest in environmental conservation measures, and it is difficult to introduce them as they are in developing countries where economic growth is a higher priority than environmental conservation. In my research, I focus on wastewater treatment using photosynthetic microorganisms that utilize the nearly infinite energy of sunlight. For example, instead of the conventional activated sludge method that requires mechanical aeration, I am conducting research on wastewater treatment using a "microalgae-bacteria coexistence system" that combines photosynthesis by microalgae with removal of organic pollutants by bacteria, and wastewater treatment using "purple photosynthetic bacteria" that have the characteristic of accumulating useful components such as proteins, carbohydrates, PHA, and carotenoids in their bodies by utilizing organic pollutants and nutrients in wastewater. These technologies are particularly suitable for use in the relatively warm and sunlight-rich region on Earth, located between 35 degrees north and 35 degrees south latitude, known as the Sunbelt region. The Sunbelt region is home to developing countries in Latin America, Africa, Southeast Asia, and other areas where wastewater treatment is not widely used. I hope that by advancing research and development of this technology and accumulating knowledge and know-how, it will mature into a next-generation wastewater treatment technology that can be introduced and disseminated regardless of the presence or absence of an economic foundation. Our university will mainly conduct basic research, while applied research and demonstration tests will be carried out with collaborative research institutions in Mexico, Ethiopia, and other countries. Applicable projects: Development of nitrogen-containing wastewater treatment technology by microalgae-nitrification symbiotic process using flow carriers Japan Society for the Promotion of Science Grant-in-Aid for Young Scientists (B) 17K12851 (2017-2018) Principal Investigator URL: https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-17K12851/ Treatment of wastewater containing high concentrations of nitrogen by a symbiotic system of microalgae, nitrifiers and denitrifiers using sponge carriers Japan Society for the Promotion of Science Overseas Research Fellowship 201860754 (2018-2020) Principal Investigator URL: https://www.jsps.go.jp/j-ab/ab_list/list_h30.html Low-cost treatment of nitrogen-containing wastewater using microalgae-nitrifying bacteria immobilized light-blocking gel: A case study in Mexico Japan Society for the Promotion of Science, Grants-in-Aid for Scientific Research, International Joint Research Acceleration Fund (Strengthening International Joint Research (B)) 20KK0249 (2020-2024) Co-investigator URL: https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-20KK0249/ Advanced treatment of poultry farm wastewater and production of useful substances by purple photosynthetic bacteria-methane fermentation coexistence system Maekawa Hoonkai Academic Research Grant 2020 (2020-2022) Principal Investigator
- Development of resource-recycling urine treatment technology for long-term human activities on the lunar surface
Space is the greatest frontier remaining for humanity. Its development will expand the human habitat and area of activity, lead to the acquisition of useful mineral resources, advances in science and technology through research using the space environment, and the creation of space utilization industries, and will greatly contribute to the development of a rich and sustainable society. In recent years, the race to develop space has intensified among developed countries, and space development organizations such as NASA, JAXA, and space development organizations in Europe, China, and India are promoting projects. There is a common understanding that the next 30 years will focus on lunar development in particular, and the goal is to build a manned settlement on the moon in the 2040s and begin industrial use such as the involvement of private companies and tourism by the general public. In settlements on the moon, resources essential for human survival such as water, oxygen, and food are extremely limited. Therefore, technology to recycle resources within the settlement is essential for long-term manned activities. In particular, urine is produced daily and contains abundant nutrients such as nitrogen and phosphorus, so it is considered to be one of the resources that should be most utilized during long-term manned activities in space. Microalgae can purify nutrients in urine through photosynthesis, and the microalgae biomass produced has the potential to be used for functional foods, biofuels, animal feed, and other purposes. Furthermore, urine treatment using microalgae is expected to remove carbon dioxide and supply oxygen, which are essential for maintaining life in space facilities, making it a suitable technology for lunar habitats. In my research, I am conducting basic research into, for example, how a microgravity environment affects the metabolism of microalgae, with the aim of establishing a technology for recycling urine resources based on microalgae. Applicable projects: Development of lunar urine treatment technology using lunar regolith immersion - a coexistence system of microalgae and flocculated nitrifying bacteria Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research (B) 21H03665 (2021-2024) Principal Investigator URL: https://kaken.nii.ac.jp/ja/grant/KAKENHI-PROJECT-21H03665/
- Development of high-speed methane fermentation processing technology for aquatic plant biomass that grows excessively in Lake Tana, Ethiopia
The vast Lake Tana, the source of the Nile River, is known as a place rich in natural environment and scenic beauty. However, currently, the lake surface of more than 500 km2, which is equivalent to the area of Tokyo's 23 wards, is covered with water hyacinth, causing harm to more than 500,000 agricultural and fishing workers, and the establishment of appropriate management and treatment methods is a national priority. Since 2020, our university has been working to solve these problems after being selected for the Science and Technology Research Partnership for Sustainable Development (SATREPS) program by the Japan Science and Technology Agency (JST) and the Japan International Cooperation Agency (JICA). Specifically, we aim to establish a water hyacinth management method using Information and Communication Technology (ICT) such as remote sensing technology for Lake Tana, and to develop a series of systems that convert the collected water hyacinth into valuable materials (microalgae, agricultural crops, etc.) through high-speed methane fermentation and carbonization after squeezing it. In my research, I am working to develop high-speed methane fermentation technology for water hyacinth juice, by investigating energy-saving, low-cost pretreatment methods for the juice and fixed-bed methane fermentation methods that use locally available waste materials such as bagasse as a microbial carrier. Applicable projects: Establishment of a method for managing and effectively utilizing the excessive aquatic plant biomass in Lake Tana, Ethiopia, the source of the Nile Japan Science and Technology Agency (JST) Japan International Cooperation Agency (JICA) International Science and Technology Research Partnership Program for Sustainable Development (2020-2025) Research Co-Investigator (Theme 2 Leader), Project Manager URL: https://www.jst.go.jp/global/kadai/r0205_ethiopia.html https://www.youtube.com/watch?v=WdPNfQOv3Lk
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Main Papers and Publications |
book
- Akizuki, S., S., Sato, S. Addis, G. Cuevas-Rodríguez (accepted).
Treatment of piggery wastewater with an integrated microalgae-nitrifiers process: current status and prospects.
-Integrated and Hybrid Process Technology for Water and Wastewater Treatment, Edited by W. Ang and A. Mohammad, Elsevier, BV, Amsterdam.
Overview
- Akizuki, S., Nishi, K., Toda, T., and Ida, S. (2020).
Immobilization technology aimed at reducing photoinhibition of nitrifying bacteria. -Chemical Engineering, 65(1): 19-24.
Academic Papers (peer reviewed)
- Akizuki S., K. Izumi, N. Nagao, T. Shiotani, C. Niwa, T. Toda (2013).
Effect of COD/NO3−–N ratio and seed sludge on simultaneous methanogenesis and denitrification in intermittent organic solid waste treatment.
- International Biodeterioration & Biodegradation, 83: 8-13.
- Akizuki, S.*, T. K. Wong, Y. Aoki, G. Cuevas-Rodríguez, C. Niwa, T. Toda (2015).
Effects of substrate COD/NO2−-N ratio on simultaneous methanogenesis and short-cut denitrification in the treatment of blue mussel using acclimated sludge.
- Biochemical Engineering Journal, 99: 16-23.
- Akizuki, S., T. Matsuyama, T. Toda (2016).
An anaerobic-aerobic sequential batch system using simultaneous organic and nitrogen removal to treat intermittently discharged organic solid wastes.- Process Biochemistry, 51: 1264-1273.
- Kodera, T., S. Akizuki, T. Toda (2017).
Formation of simultaneous denitrification and methanogenesis granules in biological wastewater treatment.
- Process Biochemistry, 58: 252-257.
- Akizuki, S., N. Nagao, T. Toda (2018).
A multifunctional single-stage process for the effective methane recovery and denitrification of intermittently discharged wastes.- International Biodeterioration & Biodegradation, 127: 201-208.
- Akizuki, S., T. Toda (2018).
An anaerobic-aerobic sequential batch process with simultaneous methanogenesis and short-cut denitrification for the treatment of marine biofoulings.
- Waste Management, 74: 168-176.
- Sekine, M., S. Akizuki, M. Kishi, T. Toda (2018).
Stable nitrification under sulfide supply in a sequencing batch reactor with a long fill period.
- Journal of Water Process Engineering, 25: 190-194.
- Praveena, S. M., S. N. Mohamad Shaifuddin, S. Akizuki (2018).
Exploration of microplastics from personal care and cosmetic products and its estimated emissions to marine environment: An evidence from Malaysia.
- Marine Pollution Bulletin, 136: 135-140.
- Akizuki, S., G. Cuevas-Rodríguez, T. Toda (2019).
Microalgal-nitrifying bacterial consortium for energy-saving ammonia removal from anaerobic digestate of slaughterhouse wastewater.
- Journal of Water Process Engineering, 31: 100753.
- Fujiwara, M., M. Koyama, S. Akizuki, K. Watanabe, K. Ishikawa, S. Ban, T. Toda (2019).
Seasonal changes in the chemical composition and anaerobic digestibility of harvested submerged macrophytes.
- BioEnergy Research, 13: 683-692.
- Akizuki, S., M. Kishi, G. Cuevas-Rodríguez, T. Toda (2020).
Effects of different light conditions on ammonium removal in a consortium of microalgae and partial nitrifying granules.
- Water Research, 171: 115445.
- Sekine, M., S. Akizuki, M. Kishi, N. Kurosawa, T. Toda (2020).
Simultaneous biological nitrification and desulfurization treatment of ammonium and sulfide-rich wastewater: Effectiveness of a sequential batch operation.
- Chemosphere, 244: 125381.
- Liu, X., M. Fujiwara, T. Kodera, K. Watanabe, S. Akizuki, M. Kishi, M. Koyama, T. Toda, S. Ban (2020).
Conditions for continuous cultivation of Chlorella sorokiniana and nutrient removal from anaerobic digestion effluent of aquatic macrophytes.
- International Biodeterioration & Biodegradation, 149: 104923.
- Nishi, K., S. Akizuki, T. Toda, T. Matsuyama, J. Ida (2020).
Development of light-shielding hydrogel for nitrifying bacteria to prevent photoinhibition under strong light irradiation.
- Process Biochemistry, 94: 359-364.
- Iweh, N. S., M. Koyama, S. Akizuki, S. Ban, T. Toda (2020).
Novel wet-solid states serial anaerobic digestion process for enhancing methane recovery of aquatic plant biomass.
- Science of The Total Environment, 730: 138993.
- Akizuki, S., N. Natori, G. Cuevas-Rodríguez, T. Toda (2020).
Application of nitrifying granular sludge for stable ammonium oxidation under intensive light.
- Biochemical Engineering Journal, 160: 107631.
- Sekine, M., A. Yoshida, S. Akizuki, M. Kishi, T. Toda (2020).
Microalgae cultivation using undiluted anaerobic digestate by introducing aerobic nitrification–desulfurization treatment.
- Water Science and Technology, 82: 1070-1080.
- Akizuki, S., G. Cuevas-Rodríguez, T. Toda (2020).
Anaerobic digestion effluent treatment using microalgae and nitrifiers in an outdoor raceway pond with fluidized carriers.
- Water Science and Technology, 82: 1081-1091.
- Qian, J., X. Liu, S. Ban, M. Fujiwara, T. Kodera, S. Akizuki, T. Toda (2020).
pH treatments in continuous cultivation to maximize microalgal production and nutrient removal from anaerobic digestion effluent of aquatic macrophytes.
- Journal of Applied Phycology, 32: 3349-3362.
- Akizuki, S., G. Cuevas-Rodríguez, T. Toda (2021).
Nitrification of anaerobic digestate using a consortium of microalgae and nitrifiers in an open photobioreactor with moving bed carriers.
- Chemosphere, 263: 127948.
- Cervantes-Avilés, P., J. B. Durán Vargas, S. Akizuki, T. Kodera, J. Ida, G. Cuevas-Rodríguez (2021).
Cumulative effects of titanium dioxide nanoparticles in UASB process during wastewater treatment.
- Journal of Environmental Engineering, 277: 111428.
- Akizuki, S., H. Joo, M. Koyama, T. Toda (accepted).
Mechanism of cell proliferation during starvation in a continuous stirred tank anaerobic reactor treating food waste.
- Bioprocess and Biosystems Engineering.
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