Spectrum Logo
A non-profit publication of the Office of the University Relations of Virginia Tech,
including The Conductor, a special section of the Spectrum printed 4 times a year

BioConverter system safely treats infectious medical waste

By Liz Crumbley

Spectrum Volume 17 Issue 36 - July 13, 1995

A unique infectious-waste disposal method that uses chemicals and naturally occuring enzymes to destroy dangerous pathogens has been developed by BioConversions Technologies (BCT) of Roanoke and the Virginia Center for Innovative Technologies (CIT), with the expertise of researchers from the Virginia Tech Department of Mechanical Engineering and College of Veterinary Medicine.

Since August 1994, the BioConverter system has been turning 1,500 pounds per day of waste at Lewis-Gale Hospital in Roanoke into environmentally safe materials. So far, Lewis-Gale is the only facility in the United States using the BioConverter, but BCT is considering proposals for installation of the system at hospitals in other states and at Virginia Tech. The company also is designing a larger version of the BioConverter for use as a regional infectious waste disposal system.

About 100 incinerators in Virginia are turning most of the state's 21,000 tons per year of infectious waste into ash and air emissions. Virginia recently lifted a moratorium on licensing new medical-waste incinerators, and new regulations for incinerators have been hotly debated in the state.

Clark Fuqua, the president of BCT and a medical-device engineer, began working on an alternative to medical waste incineration about six years ago. "There's strong evidence that hospital incineration emissions are high in dioxin," Fuqua said.

To achieve low emissions rates, incinerators must burn constantly and the incineration of plastics increases emissions rates. Fuqua said hospitals have to dispose of plastics and typically do not have enough waste to run incinerators constantly.

The solid and liquid remains of the waste treated in the BioConverter at Lewis-Gale are safe for final disposal in Roanoke's municipal landfill and sewage system. Rebecca Clark of the Virginia Department of Environmental Quality said the system's final product contains no toxic residue, and the BioConverter has met the requirements of "an alternative treatment for regulated medical waste."

Ingenuity was needed to find the right combination of expertise to bring Fuqua's original concept to reality. The CIT, which helped fund the development of the BioConverter, put Fuqua in touch with Virginia Tech mechanical engineering and veterinary medicine researchers. Together, they designed a treatment system that handles every type of medical waste--including bandages, bodily fluids, bloody sheets, metal surgical instruments, garbage bags--except radioactive waste and chemotherapy drugs.

Charles Reinholtz and Alan Kornhauser, professors of mechanical engineering at Tech, were recommended by the CIT to design the system, which consists of a hopper that receives waste, a shredder that grinds the waste into particles, a HEPA filter for exhaust, an enzyme and chemical reaction tank where pathogens are destroyed, and a tank in which the treated liquids and solids are separated.

The mechanical design of the BioConverter posed special challenges, because the system has to grind several types and weights of materials at once, Reinholtz said. "The biggest problem we had was figuring out how to shred everything from metal to linens to plastic bags."

Shredding reduces the volume of hospital waste and also allows the BioConverter's enzymes and chemicals to attack bacteria, viruses, and spores. Thomas Toth, Nammalwar Sriranganathan, and the staff at Tech's veterinary school experimented with combinations of various enzymes, chemicals, temperatures, and pH levels to find the correct range within which the enzymes and chemicals would destroy the full spectrum of hospital pathogens.

The enzymes in the BioConverter attack pathogens in much the same way that enzymes in our digestive systems attack food. One enzyme used in the bioremediation system reduces the quantity of paper waste by breaking up complex carbohydrates; a second enzyme renders viruses harmless by digesting proteins, while the chemicals inactivate bacteria and spores. By the time waste comes out the other end of the BioConverter, it is reduced in volume by as much as 60-70 percent and is no longer infectious.

The 1995 Virginia General Assembly authorized a $1.6-million capital project for an infectious-waste disposal system at Virginia Tech. John Kuykendall, assistant to the university architect, said the university is proposing to conduct a pilot project to determine whether the BioConverter system can be modified to handle the special needs at Tech. "The bioconversion process shows a lot of promise," Kuykendall remarked.