By Peter Chawaga, Associate Editor, Water Online
All too often, nutrient pollution issues from industrial and agricultural wastewater operations fall on local utilities to solve.
To be fair, it’s no easy task for these operations to remove all the nutrients from their effluent before it reaches source water. But one dairy system in Washington state has taken steps to change this.
“Out of the Columbia Basin, a system of worm feces, wood chips and river rocks could spell a new solution to a vexing issue of nitrate pollution and greenhouse gas,” reported the Yakima Herald. “To deal with nitrate-laden wastewater generated by some 7,000 milk cows, the Royal Dairy in Royal City … commissioned a Chile-based company to build what is the largest treatment facility of its kind in the world.”
According to the Herald, Royal Dairy’s new system takes place over three large boxes of soil permeated with about 1,000 worms per cubic foot. Below that is a layer of wood shavings and, below that, a layer of river rocks. When the worms’ excrement combines with other microbes, a biofilm is produced and it attaches to the wood chips and rocks. This biofilm captures the nitrates as the wastewater travels through the system and the worms eat them.
The process takes about four hours, is capable of treating 200,000 gallons of wastewater per day, and cost the dairy about $2 million. If it truly works, it could prove to be a much-needed solution for similar operations around the country.
“Nitrates have become a big issue for many dairies,” the Herald reported. “When manure is flushed from farms with water and reused for irrigation, nitrates from the manure can seep into the soil, potentially contaminating drinking wells. High levels of nitrates in the water cause health problems, especially for pregnant women and young children.”
To read more about getting rid of nitrates visit Water Online’s Nutrient Removal Solutions Center.
Image credit: "Dairy," Alabama Farmers Federation © 2011, used under an Attribution 2.0 Generic license: https://creativecommons.org/licenses/by/2.0/