The key to solving many of the world's hazardous-waste problems may be rotting on forest floors, a Utah State University biochemist says.
Five years ago, Steven D. Aust, USU's director of biotechnology, found that white rot fungus, a powdery organism commonly found in rotting wood, can degrade many hazardous materials.The substances include dichlorvos (DDT), polychlorinated biphenyls (PCB), creosote, coal tar, dioxin and many other harmful and possibly carcinogenic substances, he said.
White rot fungus thrives on cellulose and secretes enzymes to break lignin down. The same enzymes can break down hazardous waste, Aust said.
"Most bacteria absorbs something, then degrades it," he said. "But white rot fungus secretes enzymes to break down a material."
So far, the fungus has degraded the 50 to 60 solid and liquid hazardous wastes tested, Aust said. Some wastes degrade within days. Others take long periods of time.
The best results have come from tests on creosote, coal tar and pesticides.
Last summer, Aust took his white rot fungus experiments out of the lab and into the field to a Utah Power & Light Co. site in Idaho Falls, where power poles were treated with creosote, with promising results.
"They have wells pumping groundwater there, and the ground is contaminated, so we were trying to clean both soil and water," Aust said.
Wooden boxes were built, and contaminated soil placed inside. The white rot fungus was added, and within 40 days the hazardous waste degraded in some of the plots, he said.
Aust now is convinced he is ready to work on other sites contaminated with coal tar, creosote and pesticides. Pesticide-contaminated orange groves in California's Orange County, and possibly carcinogenic sites where coal was converted to gas for lamps before electricity was widely available, are of particular interest to him.
"One of the best hazardous materials I'd like to work on is DDT in Orange County," he said. "DDT was used for years in orange groves, and luckily the DDT stuck on top of the soil. This technology should be effective and cheap enough to take care of that."
Cleaning coal conversion sites, commonly called "town gas" sites, may also be equally quick and effective, Aust said. There are about 2,000 such sites in the United States.
"When you convert coal to gas, you only convert about 50 percent," he said. "The rest was usually dumped on the site so there are carcinogenic chemicals all over the former town gas sites."
Aust believes his white rot fungus research eventually can be used to clean hazardous wastes at old implement shops, car salvage yards and metal salvage yards.
He first published a paper on white rot fungus four years ago, and he said he receives three to four inquiries about his research each week.
"Everyone around the world is jumping on this," he said.