ITHACA, N.Y. — Cornell University is not letting cow waste, well, go to waste by converting it into clean bedding for its dairy cows and a power source for the City of Ithaca.
At the Cornell Teaching Dairy Barn on Thursday, as part of the work of keeping the 200 dairy cows fed, cared for and milked, a worker in a Bobcat scraped muck from the stalls into the “manure reception pit,” which holds a sloppy mixture of sand and manure.
“You can’t make milk without making a lot of cow manure,” said Paul Jennette, director of biocontainment operations at Cornell’s College of Veterinary Medicine. “And you can’t have dairy without the dairy air, they say.”
Before long, the sand-manure mixture in the pit is processed and separated. More than 95 percent of the sand is reused for bedding and the separated liquid manure is transported to the Ithaca Area Wastewater Treatment Facility, where it is used for power.
Courtesy of Cornell University, here’s a breakdown of how the system works:
Sand is considered state-of-the-art bedding for cows that more and more dairy farms are using. The sand is more comfortable for the cows, who will roost on it for up to 17 hours per day, and a healthier alternative to organic matter like wood chips or hay because there is less bacteria growth, Jennette said.
Previously, the manure from the Cornell Teaching Dairy Barn was used as fertilizer on commodity crops kept by the College of Agriculture. However, the school stopped growing those crops for economic reasons about a year ago and no longer needed the manure. So they needed to figure out something else to do with all the manure, Jennette said.
“We looked at what other farms were doing and we found … a few of them had implemented this sand separation technique that we have,” Jennette said.
He said they worked with the manufacturer of the technology to implement a relatively new version better suited for a small-scale operation. Most other dairy farms that use the technology have over 1,000 cows.
The technology works by pulling in the sand-laden manure from the reception pit. It’s then diluted with recycled separated manure and filtered through a course screen to remove big chunks of hay and other debris. It is then pumped through a cyclone that as it spins, separates most of the manure from the sand. It is processed a little more to separate any remaining manure and is eventually sprayed down with tap water as a final step before being dried.
The technology has two main benefits: it helps prevent the need to truck 30 tons of sand into the facility every week, which has financial and environmental benefits and makes the manure easier to work with. Cornell already operates a “carcass digester” with a liquid end result. That combined with the liquid manure are trucked down to the Ithaca Area Wastewater Treatment Facility for processing.
C.J. Kilgore, chief operator of the Ithaca Area Wastewater Treatment Facility, could not be reached for comment Friday but previously told the Cornell Chronicle that microbial activity breaks down the manure along with other organic matter and generates methane gas in the facility’s anaerobic digester, which is like a big fermentation system. The methane gas is used to run microturbines to generate electricity to help power the facility and reduce their electric load.
In total, Cornell trucks 40-50,000 gallons of liquid waste to the facility a week. Though it sounds like a lot, the treatment plant on average treats about 6.5 million gallons of sewage daily. In addition to what Cornell trucks in, the facility treats septage, landfill leachate and municipal sludge.
The manure-sand separating system is an operational benefit to Cornell and will pay for itself over time, Jennette said.
“It’s a win-win for us,” Jennette said. “Yes it costs some money so there’s a longer payback, but the win win is that we get to use sand bedding that’s healthier for the cows, recycle that sand or reuse that sand and not have to truck sand in and out of the facility all the time and then have an energy benefit, an environmental benefit.”
Featured image: Cows in the Cornell Dairy Teaching Barn rest Thursday. (Kelsey O’Connor/The Ithaca Voice)