Biodigesters: Transforming Waste into Gas and Fertilizer

Looking for a creative way to turn waste like manure and food scraps into something useful? Biodigesters offer farmers a smart solution — recycling nutrients and producing renewable cooking gas in the process.

The liquid digestate can be applied directly as a nutrient-rich fertilizer, while the solids can be dried and reused as animal bedding, the EPA explains. 

Additionally, the use of a biodigester is an NRCS Conservation Practice (Code 366). To learn more about biodigester resources and support that may be available, contact your local NRCS office. Use this locator to find the office closest to you. 

Biodigesters at Tierra Viva Cantalagua 

At Tierra Viva Cantalagua, Jennifer (Jenni) González and her family have two biodigestors that provide them with both gas and fertilizer while also helping to recycle nutrients – one of a multitude of sustainable practices that the farm implements. Tierra Viva also provides consultations and installations of biodigester systems and welcomes visitors to their educational farm who are curious about these systems. 

"All these technologies also involve a commitment,” Jenni says. 

The family’s farm in the community of Los Criques, in San Ramón de Alajuela, Costa Rica, incorporates biodynamic, integral and regenerative agricultural practices, flowing with natural rhythms and intentionally improving soil health. In a previous edition of the Green Corner, we highlighted Jenni and Tierra Viva’s composting practices.  

One of the farm’s two biodigesters receives black and grey water that comes from the family’s home – preventing this wastewater from reaching the groundwater. This system produces digestate that is used to fertilize ornamental plants at the farm, while gas from the system returns to the house through a system of pipes which also connects to a second biodigestor system. The gas from the two systems is used for cooking – and sometimes for fueling a gas-powered water heater. 

The second biodigester system at Tierra Viva has a slightly different setup. The family adds food scraps, manure, and a little bit of water to this system. (Manure helps to speed up the process.) The digestate this system produces is funneled to an array of tanks that holds the digestate until it is used to fertilize crops, Jenni explains.  

Resources 

If you’re interested in learning more about biodigesters or would like to start your own system, check out this article from our friends at the National Center for Appropriate Technology. It features a biodigester system installed at Dickinson College Farm in Pennsylvania, supported by NRCS and a local dairy farm. The article also includes practical tips and links to resources for starting your own small-scale biodigester.

Contact us at info@asekia.org with any questions – we’re excited to connect with you!