Established nearly 100 years ago, Meijo University is one of the largest universities in the Chubu region of Japan. The learning institution is known for its strong research capabilities, and of particular importance to the university is its pursuit of sustainability and carbon neutrality.
Water resource depletion is a serious global problem caused by a variety of factors, including population growth, climate change, and overuse of water resources. Severe droughts in the Middle East, Africa, and parts of North America, for example, continue to cause water demand to exceed supply. Intensifying climate change and inefficient water management are further exacerbating the situation, with significant impacts on agriculture, industry, and the daily lives of millions of people. It is therefore essential to rethink water resource management. In your opinion, what are the main obstacles to achieving sustainable water resources management globally, especially as climate change intensifies?
Climate change is causing a marked difference between areas that receive rainfall and those that do not. In addition, rainfall is becoming more concentrated, resulting in flooding, which makes it impossible to use water effectively. In terms of water resource management, we believe it is necessary to enhance the water storage function as well as flood control.
The cost of transporting water is very high and energy consuming, making it inefficient to transport to areas where water is scarce. We believe that it is desirable to use water in a cyclical manner in each region. Used water becomes a resource when it is treated appropriately. We believe that efficient water use can be achieved by selecting the most appropriate water treatment technology according to the contamination of the water, setting the treatment level according to the intended use, and considering not to over-treat the water. In addition to the development of water recycling technology, it is also very important to prepare people to accept the use of recycled water.
I belong to the Department of Environmental Technology, Faculty of Science and Engineering, Meijo University. My main research areas are water resource conservation technology and water resource recycling technology that combines biological functions and separation technology.
Could you tell our readers about your research field and the major research projects you are currently working on?
I am developing various technologies for water purification. We are developing a portable water treatment system with membrane filtration technology at its core, which will be useful in times of disaster and in areas without water infrastructure. We are also developing the use of microorganisms that are not generally used in water treatment but have special abilities, such as the ability to break down persistent substances. Furthermore, we are also working on the effective use of sludge, which is always discharged in the microbial treatment of water.
In 2023, a research project entitled “Development of Advanced Dehydration Processes for Conversion of Sewage Sludge into Biofuel” was initiated in the professor's laboratory as part of the 2023 Academic Research Grant Research Results Deployment Project. In addition, a jointly authored paper on ultrasonic treatment and recoagulation of sludge was published this year.
What are the main research goals of this project and what do you see as the main areas of future application for this technology?
Sewage sludge is thickened, dewatered, and incinerated, and the incinerated ash is used for construction materials. However, since 80% of sewage sludge is organic, it can be considered biomass and has the potential for other effective uses. It can be used as a raw material for biofuel or SAF (Sustainable Aviation Fuel). We believe that the organic components of sewage can be used as energy, which is not only renewable, but can also make a significant contribution to the realization of carbon neutrality. A major problem at present is that sewage sludge has an extremely high water content of over 99% when it is generated, and it is difficult to dewater. If a large amount of energy is invested in removing the water content, it will be difficult to use the sludge as a fuel. Therefore, we are developing a technology to dewater sludge in an energy-saving operation. Since sludge contains microorganisms that have grown through sewage treatment, the water content will not decrease unless the water in the microorganism cells (equivalent to 60-70%) is discharged. In a recently published paper, we showed that ultrasonic treatment of sludge for a very short time facilitates the expulsion of intracellular water.
Another major area of research is advanced water treatment and water resource recycling technologies that utilize biological functions and separation techniques. We study how natural processes purify water contaminated by humans, utilizing the special functions of living organisms to detoxify toxic substances and use the water as recycled water.
How do you see the practical applications of this technology being realized in the industrial sector and at the municipal level?
For example, plate tests can be used to identify microorganisms that have the ability to degrade dyes. If we can understand the mechanism of this biological function, and if we can prepare the environment by using separation technology and other means so that it can be used in water treatment, we can realize decolorization treatment of wastewater from dyeing factories. Understanding the biological function and creating the environment are important, and if we can clear these issues, I think it can be applied to a variety of applications.
Next, as a technical question, I would like to ask you in relation to specific applications of this technology. In a closed water recycling system, what measures are you taking to sustain biological functions for a long period of time and ensure efficient operation? Also, what mechanisms are in place to prevent biofouling (biological contamination) and degradation?
We have not yet reached the stage of long-term operation, but we are taking the following steps. There are two processes: the production of enzymes by microorganisms and the degradation of environmental pollutants by enzymes. By separating and optimizing these two processes, we believe it will be possible to utilize biological functions over a long period of time.
White rot fungi are one of the primary biological materials used in wastewater treatment and remediation research, where separation membranes are used to create a microbe-free environment for the microorganisms to function.
What are the main characteristics and special abilities that make white rot fungi suitable for this application?
White rot fungi are members of the wood-rotting mushroom family and are able to break down lignin, a persistent polymer that is a major component of wood. It can be extracted from white rotten wood, but when it is used for water treatment, the environment, including the amount of water and surrounding microorganisms, can vary greatly. Therefore, the special ability it possesses may not be expressed, making its application to water treatment difficult. We have the ability to decompose various environmental pollutants such as dioxins, PCBs, environmental hormones, synthetic polymers, pesticides, pharmaceuticals, and dyes, and we are working to create an environment that allows these functions to be realized. By preparing a microbe-free environment with separation membranes and using waste molasses from food waste as a nutrient source, we have found that the enzymes involved in the degradation of environmental pollutants can be efficiently produced.
Meijo University is known for its strong research capabilities, as part of the MS-26 program, and is committed to improving its research capacity and strengthening its research base. Meijo University is also famous for its Nobel Prize-winning research on blue LEDs and continues to conduct innovative research in a wide range of fields. What do you consider to be the main strengths of Meijo University's research capabilities?
Meijo University offers an environment conducive to devoting oneself to research. Meijo University has established the “Carbon Neutral Research Promotion Organization” with the aim of realizing a carbon neutral society, which has become a hot topic in recent years. The Organization for the Promotion of Carbon-Neutral Research has been working to realize Meijo University's goal of “creative practical learning” through the promotion of research that contributes to carbon neutrality.
For more information, visit: www.meijo-u.ac.jp/english
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