In goes the waste food, plastic packaging and all, and the outcome is just liquid and gas, with no solid waste. (Sunface)

Plastic is notorious for the harm it causes to the environment as a result of its resistance to biological degradation. But moves are afoot to render it into a less permanent substance. Some are targeted at the disposal of conventional petroleum-based plastic used in packaging, such as plastic bags and styrofoam containers. One new method in this category uses microorganisms to break plastic down into water and carbon dioxide. Others are focused on the production of plastic from vegetable matter like corn instead of petroleum. In either case, plastic that does not need to be separated from other waste for disposal is the end result.

Putting 240 Microorganisms to Work
An environmentally friendly way of disposing of waste food containing plastic was developed jointly by Sunface (site is Japanese only), an environmental-technology company located in Suita City, Osaka Prefecture, and Hideaki Miyata, a professor at Setsunan University in the Faculty of Pharmaceutical Sciences. This "biodisposer" (which is being marketed under the name Kuishinbo) was made public in November 2002. Afterwards, the small company was overwhelmed with inquiries, and in just two weeks its website received 20,000 hits.

The process has two steps. First the waste food along with any plastic packaging, such as bags or styrofoam containers, is put through a crusher. Next it is introduced to the main unit, where a mixture of approximately 240 types of microorganisms go to work on it, breaking the food and plastic down into such natural substances as water and carbon dioxide. The liquid content is recycled back into the degradation process, where it helps to sustain the microorganisms. The gaseous content is passed through a deodorizer to remove the odor, which is mainly caused by ammonia, and released into the environment.

Under the Food Recycling Law, businesses that produce food waste, such as hotels, supermarkets, and companies with cafeterias, must take steps to recycle it, and many such firms have expressed interest in the device. Nobuyoshi Shimosako, president of Sunface, reports, "We've already provided our system to Toyota Motor and Mori Building."

Corn-Made Plastic Taking Root in Japan
The production of biodegradable plastics made from substances other than petroleum has been making headway. One method uses polylactic acid derived from corn as the raw material. Technology for this became practical in Europe in the late 1980s and was introduced to Japan in the early 1990s. Bags made out of this type of plastic can be crushed and composted with the rest of the food waste. In other words, they can be returned to the soil without damaging the environment. The rubbish releases heat (about 60 degrees Celsius, or 140 degrees Fahrenheit), which initiates a hydrolysis reaction that breaks the polylactic acid down into smaller molecules. These molecules can be more easily consumed by microbes, which complete the decomposition process. Again water and carbon dioxide are about all that remain at the end.

All sorts of products can be made from biodegradable plastics, not just plastic garbage and shopping bags and agricultural materials like pots for plants. These plastics are also coming into use for such office supplies as pens and rulers and for computer parts. And automakers have recently been exploring their use in auto parts.

While biodegradable plastics are not yet widespread - they account for less than 1% of all plastic produced - their use is growing steadily. One institute projects that demand for them in Japan, which rose from 4,000 tons in 2000 to 6,000 tons in 2001, is poised for takeoff. Within 10 years or so, they may come to account for some 10% of plastic production.