Helping California’s Dairy Industry Promote Clean Water, Naturally

To protect clean water for people and wildlife — and to meet state water quality regulations — California dairy farmers are working harder to apply nitrogen to crops in more precise amounts and at the right time in the crop’s growth cycle.

Sustainable Conservation’s projects have included: promoting solids separators to remove and recycle organic matter and nutrients, and composting manure to produce a beneficial soil amendment. One of our latest efforts to reduce the risk of applying too much nitrogen (and potentially polluting local water) is to reduce the concentration of nitrogen in wastewater.

Our Role

Sustainable Conservation is demonstrating an innovative system to naturally treat nitrogen in wastewater at commercial dairies. In our pilot system at Fanelli Dairy in the San Joaquin Valley, wastewater is pumped through a series of filters to remove sand and other solids before being sprayed via sprinklers into the so-called worm box – a concrete container housing the worms and beneficial microbes, as well as layers of wood shavings and rocks. The worms consume organic matter in the wastewater as it percolates through the layers – removing approximately 90% of total nitrogen from the liquid in the four hours it takes to exit the tank.

California Polytechnic State University natural wastewater treatment system.

California Polytechnic State University natural wastewater treatment system.

Treated wastewater then moves on to irrigate the crops that feed Vic’s cows, and the worms leave behind their own nutrient-rich co-product, known as castings, that can be sold as a high-value soil amendment to operations like nurseries and vineyards. There are also notable air-quality benefits with the system, such as reduced levels volatile organic compounds, greenhouse gases and odors.

Our ultimate goal is to show the effectiveness of this low-tech clean-water solution and spur adoption of the technology in the Central Valley — especially in the San Joaquin Valley where most of the state’s dairies are located. The technology will be especially helpful in regions with limited available cropland for applying excess manure, regions that have highly permeable soils and those with shallow groundwater tables.

Sustainable Conservation previously partnered with California Polytechnic State University (Cal-Poly) to test this novel technology at the university’s research dairy — the first time the technology had been used at a dairy. The Cal-Poly system has been operational since December 2009 and has consistently removed 85-95% of the total ammonia nitrogen in dairy lagoon water, with more than 50% removal of total nitrogen and total suspended solids.

The technology was originally developed in the early 1990s by the Tennessee Valley Authority and has been used at commercial poultry and swine facilities, as well as several other non-agricultural facilities, in the southern U.S. and internationally.

Both effective and energy-efficient, this biological wastewater treatment system is an attractive option for dairy farmers who have more manure than they can utilize to fertilize their crops and are unable to acquire additional land or move the excess manure off-farm. It enables them to protect water resources and comply with Regional Water Quality Control Board nitrogen application limits.




California State Polytechnic University, San Luis Obispo

Fanelli Dairy

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