Treating waste as “artificial resources”
Achieving environment friendly resource recycling
| Department of Resources and Environmental Engineering Professor |
| Shuji Owada |
The Department of Resources and Environmental Engineering conducts education and research regarding topics ranging from the exploitation of resources to their use, recycling, disposal, and environmental problems resulting from the above activities. The Department of Resources and Environmental Engineering is one of the few places where one can study such a wide range of topics encompassing both the environment and resources.
In seeking to optimize resource recycling, the Owada Laboratory takes a technological approach to advanced component separation. Broadly speaking, separation technologies can be divided into two categories: physical separation, and chemical or high-temperature separation. Physical separation processes lack a strong theoretical background and present many unsolved problems. Resolving such problems is the main theme of this laboratory’s research.
At the lab, we refer to waste as “artificial resources.” This is because there is a need for society to reduce waste disposal by recycling more waste as artificial resources.
Waste processing processes can be roughly categorized as dismantling, comminution, sorting, smelting and refining. The problem with comminution is that it lacks precision, so the products are often contaminated with impurities and the recovery rate of valuable material is considerably low. A more advanced technology is required.
Making better use of artificial resources
by maximizing use of advanced technology
Let me give some examples of some of the cutting edge research we are conducting. “Smart comminution” and “Smart sorting” are new technology frameworks for comminution and sorting. This new cutting-edge technology makes it possible to comminute and sort materials with greater precision. Here’s how it works.
1) Smart comminution
When comminuting and sorting waste, efficiency could be greatly increased if it were possible to first extract reusable items, since this would greatly improve the rates of reutilization and/or material reuse. For example, a computer is made up of all sorts of assemblies, such as keyboards, monitors, circuit boards and so on. If those assemblies could be broken up into their separate parts, they could be reused in their existing form.
The process of breaking the individual parts of such an item into separate components is called “liberation.” And the process which makes full use of the latest technology to liberate such components is called “smart comminution.”
2) Smart sorting
Once components have been liberated, they must be sorted.
Past practice has been to use different types of machinery to concentrate particular types of component material, but recently the hardness, density, chemical composition, etc. of solids running on a conveyor belt can be detected for example using X-rays and special lasers, and desired component types can be separated from other materials using puffs of compressed air. This process is referred to as “smart sorting.”
In 2015, we developed a LIBS* sorter which uses smart sorting technology. This sorter irradiates the material to be sorted with a laser which instantaneously heats the surface of the material to plasmatize it. By spectroscopic analysis of the plasma, it is possible to quantitatively identify a wide range of elements ranging from hydrogen to uranium.
* Abbreviation for “Laser-Induced Breakdown Spectroscopy.” The method uses a laser to plasmatize part of the target material for analysis of its component elements.
Research at the Department of Resources and Environmental Engineering
can also be viewed as a social experiment
I always tell my students to concentrate on “why” and “therefore”. Even if an experiment yields interesting results, they will be of no practical value if nothing can be said about “why” and “therefore.”
Education and research activities at the Department of Resources and Environmental Engineering can be regarded as a sort of a social experiment. Since this research is of high public interest, mistakes can have a profound impact on society. I regard it as my mission to continue cultivating researchers with an appreciation for the scientific method and a sense of responsibility.