Washington state dairy wows with innovative water treatment system

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.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 fee