News from the Midwest Sectional Meetings, March 16-18, 1998, Des Moines, Iowa
Contacts:
Dick Steffen, Southern Illinois University, (618) 453-6985
Tom Jirik, ASAS/ADSA Media Coordinator, North Dakota State University,
(701) 231-9629.
Illinois Researchers Flex Mussels Over Swine Waste
The zebra mussel, a foreign invader that is jeopardizing freshwater ecosystems in the United States, may be put to work filtering livestock waste.
In preliminary laboratory studies at Southern Illinois University in Carbondale, researchers used the mussel to remove solids and some nutrients from diluted liquid swine waste.
"In our study we found a 90 percent improvement in water turbidity (suspended solids)," says researcher Dick Steffen. The mussels also appeared to reduce odor, although that effect wasn’t measured in the experiments.
But removing the solids from the water was significant, Steffen says. Particles as small as—and including—some bacteria were removed. "Some particles in waste-water remain suspended practically forever and are very difficult to remove," he says"
He presented results of his research at the joint Midwest meeting of the American Society of Animal Science and the American Dairy Science Association in Des Moines, March 16-18.
The zebra mussel is a natural water filter, constantly pulling water through its body. It filters out any nutrients it needs to live and coats remaining particles in a mucus-like film called pseudofeces which settle out of water.
"That ability to take bacteria and other small particles out, is where the future of this technology lies," Steffen predicts.
He is trying to determine if the mussels themselves or those pseudofeces have value as a plant nutrient. "Is there nutrient value? What processing is needed? What’s the commercial value of any products. Those are questions we need to look at," he explains. And that’s just for a start. Steffen cautions that the research is in its early stages and waste-processing using living organisms often can be fickle. "At this point, a major question is, can we keep them alive in a long-term system?" he says.
Still, he optimistically envisions a continuous processing system where zebra mussels do a lion’s share of filtering out bacteria and other particles from livestock waste. In the ideal system, waste would be flushed from barns through screens to remove the largest particles. From there the water would be routed to enclosed chambers where zebra mussels provide additional filtering. Once the mussels have done their job, the water would be recycled back to the barn for another flushing.
"We see this as an enclosed system that will keep the mussels contained. That should work best and will help allay conservationists’ concerns about spreading them any further," Steffen says.
Other researchers have looked at using zebra mussels to process municipal waste or to filter bacteria from water before it entered municipal drinking water treatment facilities. "We saw treatment of livestock waste as an obvious extension of that work," Steffen says. His research was supported by the Illinois Council for Food and Agricultural Research.
####