Published on 02/14/01

Worms Don't Mind the Waste

Earthworms have a healthy appetite. If you get enough of them together and don't disturb them, scientists say they can safely, quietly dispose of many forms of waste.

Vermiculture is a composting system that uses worms to process organic waste, said Sid Thompson, a professor of engineering with the University of Georgia College of Agricultural and Environmental Sciences.

The process could be a viable alternative, he said, for current waste-management practices that continue to grow more expensive and impractical as the world's population expands.

Goes in Bad, Comes Out Good

The earthworms don't have to be trained for vermiculture or do anything unusual. They just do what comes naturally: eat. As the worms eat organic materials, such as sludge from wastewater treatment plants, they excrete it as castings.

Worm castings, which look much like freeze-dried coffee crystals, make good fertilizer for plants. They also improve the water and nutrient-holding capacity of the soil.


Earthworms eat and convert sludge into a more environmentally safe product.
"Castings are more microbially active," Thompson said. "The nutrients are more available to plants."

The worms get rid of the harmful waste and in return provide a much nicer product that's not as smelly. Not only are the castings easy on the environment, they can catch a good price as well. Castings are advertised on the Internet for as much as $4.25 per pound.

Cities around the world are looking to vermiculture to combat waste problems, Thompson said. Vermiculture in India, one of the most heavily populated places in the world, gets rid of as much as 30 tons of waste a day.

Thompson said vermiculture could work for Georgia, too. To be viable on a large scale, though, it must be proven economically feasible.

Worms take to sludge like mice to cheese. In fact, one worm can eat its weight in sludge every day. One pound of worms can eat and process one pound of sludge.

However, a large land area would be needed for the worms to process large amounts of sludge, said Jason Governo, a graduate student working closely with Thompson's research.

A Pound of Worms Can Tell You More

Most vermiculture research uses only one or two worms in small laboratory settings. Thompson and Governo are using pounds of worms in their research.

Their studies show that only 3 to 4 inches of sludge can be placed onto the worms at any one time, Governo said. With such a thin layer, it would take too much land and wouldn't be economically feasible for Georgia.

But Thompson said the land problem could be solved simply. He proposes placing the sludge and the worms in trays and then stacking those trays in a tall structure. "There are ways this can be done for waste in the state," he said.

Thompson said worms can convert a range of organic material, as long as the material is presented in an acceptable form.

Georgia is one of the leading poultry producers in the world. It's also one of the leading producers of manure from layer hens, the birds that lay eggs. Large quantities of this manure can strain the environment.

Worms, Thompson said, could convert layer manure into a more environmentally acceptable product. However, the natural high salt and ammonia content found in layer manure dries up and kills the worms.

Vermiculture could be the answer to the large volume of chicken litter produced in Georgia, he said. Scientists just have to find the right way to present it to the worms.

Brad Haire is the former news editor with the University of Georgia College of Agricultural and Environmental Sciences.