Page 11 - Shimadzu Journal vol.3 Issue1

Interview

Contributing to Develop Environmental

Technologies Based on Biodiversity

The Earth’s ecosystem comprises a diverse variety of plants and animals. Due to the benefits we enjoy from these
ecosystems, there is increased interest, including internationally, in biodiversity conservation, sustainable use and
equitable sharing of genetic resources and associated benefits. To expand on this topic, we interviewed professor
Michihiko Ike, from the Division of Sustainable Energy and Environmental Engineering, Graduate School of
Engineering, Osaka University, who is involved in cutting-edge research on environmental technologies based on
biodiversity.

Firstly, could you please tell us about your research work? time and synthesize a semiconductor substance called cadmium
selenide. Such facts demonstrate the remarkable potential of a
My research mainly involves developing technologies for new manufacturing method that converts wastewater
cleaning up wastewater and soil by carefully using the forces containing toxic metals into high value-added materials while
of nature, such as plants and microorganisms. Nature and treating.
other earth systems are fundamentally very robust and, unless
we do something quite extreme, nature tends to clean itself to
keep the environment in constant balance. Furthermore, the
plants responsible for a part of this work generate their own
energy through photosynthesis and are able to propagate
themselves. Therefore, they are almost like a perpetual motion
machine. As an engineer, I have been focused on developing
equipment that can utilize the ability of plants and
microorganisms to decompose pollutants and so on.
In the past, my work mainly involved so-called “end-of-pipe”
wastewater treatment systems, which are analogous to our
veins. More recently, I have been thinking about integrating a
kind of manufacturing, in the form of collecting and
recirculating natural resources, which is analogous to our
arteries.

Specifically what types of methods are involved?
Take rare earth metals, for example. Due to advances in
scientific technology, this class of substances is being used in I am starting to think that microorganisms are an ideal
massive quantities. However, though they are extremely useful catalyst of purification and resource recovery, but does it
to modern industry, they also cause environmental pollution
when concentrated and discharged in effluents and gas have any problems?
emissions. As a result, these elements, such as selenium, The various actions by the microorganisms are collectively referred
nickel, and antimony, are already subject to established to as metabolism. The metabolites that result from this process
environmental standards or other regulatory limits.
sometimes include troublesome substances that can require special
In particular, selenium is an essential nutrient for humans, if processing measures. Microorganisms can often produce
taken in very small quantities, and also offers a diverse range intermediate metabolites that are chemically difficult to predict
of industrial applications, such as for semiconductor synthesis and can be quite difficult to process. For example, when
or in materials used in photocopier photoconductive drums. microorganisms decompose a type of detergent called
However, discharged water from refinery plants contains high nonylphenol ethoxylate, an accumulation of even more toxic
concentrations of selenium and coal-fired power plants emit it metabolites may occur. This is known as an endocrine disrupter
as well. Therefore, there is concern that selenium is having a and has resulted in the sex of fish changing from male to female.
negative effect on the water and soil environments.
The microorganisms clean up the detergent, but generate a
Currently, removing selenium from the environment requires an separate risk. Therefore, whenever microorganisms are used to
extremely expensive physicochemical process that consumes a decompose chemical substances, they must be investigated to
large amount of energy. However, it ends up not being determine whether or not their metabolites contain toxic
recycled, but rather either diluted to a non-harmful level or substances. Essentially, this is similar to the process of
landfilled. investigating the adverse side effects of drugs. It is also important
to investigate the growing environment and types of food that
In sharp contrast to the physicochemical process,
microorganisms are able to detoxify and recycle the substance promote microorganism metabolism or result in complete
at a low cost and modest energy consumption. Certain decomposition.
microorganisms collect the selenium and accumulate it in their In the selenium research mentioned earlier, we also have to verify
body. Therefore, we utilize that characteristic. There are also whether the microorganisms absorbed all of the selenium
microorganisms that consume hazardous cadmium at the same dissolved in the water.

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