Cleaning up after cows Revolutionizing wastewater treatment at Royal Dairy

As the office at Royal Dairy closes for the day and most of the workers go home, there are two distinct groups of workers that stay for the long haul — the thousands of cows that eat, gestate and prepare to be milked, and the millions upon millions of worms that labor to make use of what comes out of the operation’s back end.

Royal Dairy uses the BioFiltro wastewater treatment system to turn an expensive and unsightly waste-product — liquid run-off from the manure produced by thousands of heads of cattle — and turns it into irrigation water.

“One more stage of filtration and this water could be potable,” Allred said.

The old system of wastewater management was arduous and odious. First, liquid run-off needed to be separated from solid manure using slope screens and centrifuges, where it would be stored in a large lagoon that produced noxious odors and sludge. Tanker trucks would pump up 50 million gallons of that water each year and spread it as liquid fertilizer over thousands of acres of crops.

That process is expensive, but it also comes with environmental costs. Nitrogen in the ‘green water’ is absorbed by crops, but excess amounts can leach into groundwater, rivers and aquifers where it can be toxic to humans and wildlife. Phosphorus, another key nutrient found in fertilizer effluent, can feed the kind of algal blooms that have plagued the Gulf Coast and other large bodies of water where agricultural run-off is common, and can also damage wetlands.

In comes the BioFiltro, which boasts 93 percent removal of nitrogen and 90 percent removal of phosphorus on the green water that Royal Dairy filters through it. The effluent is piped into large concrete pits filled with stones, sawdust and millions of worms.

At the top, worm castings — worm poop — and sawdust filter suspended solids out of the water. Worms eat the solids and aerate the soil, which supports water flow and provides oxygen to the system. The water then passes through cobblestones inoculated with bacteria that help retain and break down waste.

The worms are arguably one of the hardest workers in the whole dairy. While milking cows eat, produce, and repeat, the millions of worms the dairy employs produce by eating, and for worms, eating is a 24-7 operation.

Worm castings are also a highly sought-after fertilizer, due to high microbial activity and physical qualities that help retain water and keep the soil aerated. Though it will still be some time before a full harvest of casings, Allred has already seen some interest for his product from local growers.

The BioFiltro system is in regular use these days, nearly a year after implementation, though Royal Dairy is still working out some of the final kinks to optimize the system. Most of those kinks are on the front-end; liquids still need to be separated from manure solids before being piped into the BioFiltro. Making these moving parts sync up like clockwork has been an involved process, but one Allred said they hope to have mastered in the coming months.

Implementation has been complicated for a simple reason: at 80,000 square-feet, the BioFiltro system Royal Dairy has deployed is the largest of its kind in the nation, and one of the few being used on a commercial dairy farm, Allred said.

The scope and goals of the project earned Allred and Royal Dairy the 2018 Outstanding Dairy Farm Sustainability Award from the Innovation Center for U.S. Dairy in May. Allred thinks back jokingly to the “very formal” event, and to the speechwriter who was assigned to him.

“I didn’t realize that it would be this big of a deal,” Allred said.

That’s because, despite the publicity and the steps taken toward sustainability, Allred had implemented the BioFiltro system because of it was practical and economical, not because it had lofty ideals. After all, Allred said, economic sustainability is key if businesses are going to become more environmentally sustainable.

“Practicality has to be the first step in anything that’s sustainable,” Allred said. “If it’s really sustainable, it’s got to last forever.”