Firm looks to expand plasma arc technology
By Jan TenBruggencate
Advertiser Science Writer
A Honolulu firm that is turning medical waste into inert glass and fuel gas seeks to expand its technology to other types of garbage.
Asia Pacific Environmental Technology is operating the state's first plasma arc furnace, under the name Hawai'i Medical Vitrification, at Campbell Industrial Park. Among the hospitals and medical facilities using the system is Kuakini Medical Center.
"We're happy with the technology. We feel that from an environmental standpoint, that's the way to go," said Darryl Ing, chief operating office at Kuakini.
The plasma arc process destroys waste, leaving no toxic compounds, no hazardous waste — just dark glass, a little metal, and a hydrogen-rich gas that can be used directly as fuel. Nothing needs to go to a landfill.
Asia Pacific is talking to county officials on O'ahu and Maui about using the plasma arc technology for destroying other kinds of waste, including household trash and sewage sludge.
"There are six plants under construction in Japan for hazardous waste," said Don-Michael Bradford, an environmental engineer and board member of Asia Pacific Environmental.
"It's kind of a new technique, but it represents quite a bit of potential," said Steven Chang, program manager for the state Department of Health's Solid and Hazardous Waste Branch. The branch has issued the Hawai'i Medical Vitrification facility a solid-waste permit. In more than a year of operation, the facility has had no notable problems with its handling of medical waste, he said.
A plasma arc furnace takes any kind of matter and subjects it to an electric arc that creates temperatures of 15,000 degrees Fahrenheit. At that temperature, molecular bonds collapse, converting potentially hazardous organic and inorganic compounds into their constituent elements.
"It's total destruction, and the end product is usable," unlike incineration systems that can require the treatment of ash as hazardous waste, Bradford said.
The lighter elements form gases that are taken off as a compound called syngas. Its largest component is hydrogen. The syngas can be used directly as fuel in a power plant, or cleaned up for use in fuel cells.
Heavier elements form a molten pool at the bottom of the furnace. Metals sink to the bottom, where they can be tapped off to form ingots for recycling. On top of the metals floats a pool of molten glass. It also is tapped off, and can be poured into molds or broken up as a sandblasting grit or into chunks that can be used in place of rock for road base.
"On average, 200 pounds of material results in one pound of glass," Bradford said.
Kuakini's Ing said the hospital always has had a liability concern about medical waste disposal. If it's shipped off, there is always the possibility a storm or shipwreck could result in the waste washing ashore, and if it's landfilled, it could be dug up.
"From an environmental standpoint, we feel confident that this resolves our concerns. It gives us better peace of mind," Ing said.
The Campbell Industrial Park unit is a Plasma Enhanced Melter that was purchased from Integrated Environmental Technologies of Richland, Wash. Information about the systems can be found at the company Web site.
The Honolulu unit was placed into service in February 2001. The firm also has units under construction or operating in Taiwan, Japan and on the Mainland.
