Seed Grant: Optimizing Energy Production, Water Treatment, and Greenhouse Gas Reductions in Low-tech Digesters


Wastewater from livestock results in contamination of waterways and the release of methane, which is a greenhouse gas with 21 times the global warming potential of carbon dioxide. When properly harnessed in a low-tech digester, however, animal waste can be transformed into an environmental and economic benefit. A digester provides an optimal environment for microorganisms, which produce methane from the carbon and nutrients in the wastewater. The digestion process results in three benefits related to Carbon, Water and Climate, respectively:

  1. renewable energy is produced from the transformation of organic matter to methane,
  2. water pollution is sharply reduced, and
  3. greenhouse gases are sharply reduced.

In addition, small-scale agricultural digesters are inexpensive and easy to build, which makes them an appropriate technology to enhance the environment and livelihoods of farmers. Currently, there are over 5 million existing small-scale digesters in India and China alone. Unfortunately, research and development in digestion technology has focused on large-scale, capital-intensive systems, which are appropriate for industrial-scale farms, but are largely inaccessible to the small farmer.

In order to address this research gap, this international project determined methods to optimize the ability of small-scale digesters to produce methane, treat wastewater, and reduce greenhouse gas emissions in Costa Rica. Specifically, we tested the impacts of codigesting grease and fats with animal manure in field-scale and full-scale digesters. By performing systematic research on low-tech digesters this research advanced the field of digestion technology and provide methods to improve digester performance. The global impact is underscored by the millions of users of low-tech digesters who will benefit from these results.

Project Status

4 publications and 4 presentations have resulted from this project as of April, 2009.

After developing knowledge about these low-cost digesters from this research, our new goal is to adapt this technology so that small and medium-size livestock farms in the United States can benefit from this technology to generate renewable energy and improve water quality. Remaining funds are now being used to support this effort and build experimental digesters at Waterman Farm.


Jay Martin
Food, Agricultural, and Biological Engineering
College of Food, Agricultural, and Environmental Sciences