Royal Dairy in Royal City, Washington has a problem that’s common to dairy farms. The hundreds of millions of gallons of water used by their dairy and beef cows eventually become wastewater carrying animal waste, nitrates, and other harmful chemicals into the groundwater which people could one day drink. 

Luckily, Royal Dairy employs a nifty solution to this problem: earthworms. 

Dirt-eaters cleaning water 

Specifically, the dairy farm uses earthworms in a process called vermifiltration. Half a million gallons of wastewater are pumped every day through a wood chip and shavings bed filled with earthworms. These worms get busy eating the manure and harmful chemicals from the water, which is then filtered through a layer of crushed rock.  After this process, the water collects at the bottom of the bed and then is pumped up to be reused again. Royal Dairy reuses its water 10 times before it leaves the farm. 

Royal Dairy is one of two farms in the United States that uses this vermifiltration installed by BioFiltro. Alfred Allred, Royal Dairy’s owner, wants to scale this process up to be used on as many farms as possible around the country. 

“[We’re] taking regenerative ag and the concepts that we’ve learned from these small-scale farms and blowing it up, to be able to feed the masses,” said Allred. 

One study conducted by BioFiltro found that vermifiltration removed 84 percent of the nitrate from wastewater. A study conducted by the University of Nebraska, Lincoln found that it reduced the nitrate levels between 53 and 61 percent. Other wastewater treatment systems are energy intensive, while these earthworms require nothing but space and time. They treat and aerate the water naturally. 

The best and cheapest option 

Not only do the earthworms keep nitrogen out of the water, but their poop helps “nutrify” the soil. The earthworms’ vermicompost contains microbes that tie nitrogen to the soil the worms live in, making a densely rich compost that farmers can sell or use on their own crops. 

Vermifiltration also helps to reduce dairy farms’ methane emissions, one of the most harmful greenhouse gasses. BioFiltro’s study found that a vermifiltration system reduced methane emissions by 97 percent. This could be a major improvement over manure digesters that remove methane but many climate advocates say aren’t foolproof. 

“Farmers are looking to clean their water up and to keep nutrients on their farm the best they can, in forms that support our soils,” Allred said. Vermifiltration is a powerful tool toward this goal.

BioFiltro’s vermifiltration system was recently approved to become a working component of the California Department of Food and Agriculture’s Alternative Manure Management Program, which offers grant funding to farmers and programs that install sustainable greenhouse-gas reducing systems.