Out on the Columbia Basin, a system of worm feces, wood chips and river rocks could spell a new solution to the vexing issue of nitrate pollution and greenhouse gases.
To deal with nitrate-laden wastewater generated by some 7,000 milk cows, the Royal Dairy in Royal City - about 25 miles northwest of Othello - commissioned a Chile-based company to build what is the largest treatment facility of its kind in the world.
Whether the system can be, or should be, widely adopted by dairies remains to be seen. But in Yakima County, where dairy cows outnumber people, and in other places with mega-size dairies, the technology is being watched carefully.
That’s because nitrates have become a big issue for many dairies. 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 can cause health problems, especially for pregnant women and young children.
Additionally, when farmers use lagoons to store their wastewater before reuse — a common practice — the large pool of untreated water can emit greenhouse gases. These problems have some state and regional water boards urging dairy farmers to switch to more environmentally friendly methods of disposal.
Austin Allred, who along with his father, Jerry, and brothers, Derek and Tyson, own and operate the Royal Dairy, was looking for a more environmentally sustainable way to dispose of the more than 1 million gallons of wastewater the dairy generates weekly. That’s when they heard about a system being used in Hilmar, Calif., that reportedly reduced gas emissions by 90 percent.
Working with BioFiltro, a wastewater filtration company based in Chile, Allred initially ran a small, two-year pilot project. Results were so promising he moved ahead this summer with a full-scale system, costing him in the ballpark of something less than $2 million; he refused to reveal an exact figure.
“I liked the simplicity of it,” he said. “I understand pipes and pumps, and this system made way more sense to me than other systems that use reverse osmosis or ultrafiltration and things like that.”
The system is divided into three large boxes, each with a dense layer of soil permeated with worms — an average of 1,000 worms per cubic foot. Underneath is a layer of wood shavings, and at the bottom is a layer of river cobble.
Worm feces, when mixed with other microbes, including bacteria, creates a sticky “biofilm” that clings to the wood chips and rocks. Nitrates and other contaminants stick to the biofilm as water percolates through the system, leaving them to be consumed by worms and microorganisms.
After 4 hours, the now-cleaner water drips into drainage basins under the beds before being used for irrigation. The system, which encompasses 81,000 square feet, treats 200,000 gallons of wastewater per day.
Kirk Robinson, deputy director of the state Department of Agriculture, said further research is needed to determine if BioFiltro’s system is the best alternative to traditional disposal methods.
“This is just one technology of many that might be an option,” Robinson said. “There’s definitely more research to be done, and a lot of farmers are given funding to do that, but we can say with confidence that we’re excited about all the new technology moving forward.”
With the system, farms no longer need to store wastewater in lagoons, which means they’ll no longer emit an abundance of gases, such as methane and ammonium — the latter of which causes the all-too-recognizable smell of most wastewater treatment facilities.
A 2015 study done at the Hilmar farm in California showed the system cut greenhouse gas emissions by 90 percent. At a ribbon-cutting ceremony at Royal Dairy last month, Frank Mitloehner, a professor at University of California at Davis who conducted the study, said the system converted the wastewater gases into a environmentally benign form of nitrogen.
Initially skeptical of BioFiltro’s promise that its system would drastically reduce greenhouse gas emissions, Mitloehner said the result surprised him.
“The test proved to me what I thought was impossible,” he said. “The system cut emissions by (90 percent); that was unbelievable, I could not believe that.”
Mitloehner cautioned that while conducted over two years, the study was only done once, and does not guarantee other farms using BioFiltro’s system will see such a dramatic decrease in emissions.