Fresno State dairy eyes earthworm technology
for wastewater treatment

A coalition of Fresno State water technology and animal science specialists has partnered with a Chile-based wastewater treatment company to test a new technology for enhancing water use efficiency on the university dairy. 

The highly innovative method employs biotechnology – earthworms – as an agent to filter unwanted nutrients out of dairy wastewater. The recycled water can then be used in a greater variety of irrigation applications.

The process is called biofiltration – featuring the use of natural organisms rather than chemical processes to recycle the water. The company, Biofiltro USA Inc., recently opened an office at Fresno State’s Water and Energy Technology (WET) Center as a start-up business in Central California.

At left, Fresno State dairy herdsman Lenny De Leon looks over the pilot-scale biofiltration unit at the campus dairy.

“Our company has developed and patented a sustainable and environmentally friendly technology for the treatment of domestic and industrial wastewater at low cost,” stated Sanjar Taromi, chief marketing officer for Biofiltro USA. “We are cleaning wastewater so it is available for broader irrigation use. In the case of a dairy, prior to recycling it was only available for flood irrigation. Recycling through our system allows the option of more efficient water use technologies, such as sprinkler or drip systems."

Biofiltro’s patented technology is relatively simple: the filtering system features a bottom layer of gravel with space for aeration and water percolation, covered by a bed of wood shavings loaded with California red worms. Wastewater is sprinkled at intervals over the worm beds. The worms thrive in the moist environment, consuming the solids in the effluent. The bacterial micro flora in the worm castings consume and metabolize nitrates, phosphorus, oils, fats and other compounds. Treatment is completed in four hours.The water percolating through is collected for reuse. It is not potable, but having been cleaned of solids and other unwanted organic compounds, it is available for a broader range of agricultural uses.

“In this sense, it does save water, because before all you could do was flood a land area and sometimes not grow anything. Now the recycled water is available for more applications,” Taromi said.

Fresno State Animal Science Professor Jon Robison, who oversees the university’s commercial dairy, welcomed the proposal made by Biofiltro last year to build a pilot-scale filtration unit on some unused ground adjacent to the dairy. He and University Agricultural Laboratory administrators agreed to partner with Biofiltro to test the process.

“I think it’s a very good concept. In the dairy waste stream there are nutrients that are beneficial to the ecosystem, and there are some compounds that are detrimental, such as nitrates and salts,” Robison said. “Where I see the value is that this process takes both the good and the bad and recycles them for useful purposes – though I’m not sure yet of the commercial application relative to a larger-scale operation.”

The filtering unit at the university dairy is relatively small (20 by 30 feet square) and processes only a fraction of the waste stream. But the key is in testing the process, Robison said.

Here’s an opportunity to discover some things that we didn’t know about,” he said. “This could be a breakthrough, as we have the opportunity to learn some things for the entire industry. The challenge is in adapting this to a full-scale commercial operation.”

At left, sprinklers spread water over the filtration bed.

Biofiltro is new to California and the United States, but not internationally, Taromi said. The company has more than one hundred installations in Chile, Brazil, Mexico, Spain and New Zealand. And the recycling technology applies not only to the dairy industry. Users include wineries, food and meat processors, municipalities, even a hotel and casino, he said.

“Biofiltro has the potential to fundamentally change biological approaches toward water treatment,” Taromi said. “Unlike conventional water treatment facilities, Biofiltro uses no chemicals – the system is all natural, and it’s very low in energy use, as essentially the only power used is to pump water through the system.”

Robison said the existing pilot project will be reviewed after one year to determine whether the technology might be expanded or recommended to the dairy industry. Biofiltro plans to build their first commercial system in California at a dairy in Hilmar this year.

Biofiltro has three more pilot projects operating in the winery, tomato processing, and municipal waste sectors in the Central Valley, Taromi said. Biofiltro is deploying pilot projects to familiarize customers and regulators with the technology, and to prove its efficacy prior to a commercial system being built

For more information on Biofiltro on the web.