Anaerobic digestion falls just behind feeding animals on the food recovery hierarchy. Diverting food waste to a food waste only digester or to be co-digested with another feedstock, e.g. manure, has a two fold benefit:
(1) food waste is being diverted from landfills and being put to beneficial use
(2) biogas production should increase
"The biogas market is continually shifting and changing, often influenced by the changes in peripheral issues or markets that can open up new opportunities. A current push by many communities for food and organic waste diversion is paving the way for new potential anaerobic digester projects. Similarly, as the drive for renewable energy and alternative fuels continues, the biogas sector is being recognized as a potential solution to help meet sustainability goals." 
Considerations when starting off
- Feedstock characteristics are very important; not all food waste is created equal. See below for some lab scale biomethane potential data on common feedstocks codigested with manure. More codigestion characterization and results data is available through both case studies and academic literature.
- Feedstock logistics including transportation, storage, and pre-processing, e.g. depackaging and grinding, also need to be considered before accepting new materials. The EPA (2014) paper cited on the right hand side of the page describes these details for each of the 6 co-digestion facilities located at water resource recovery facilities identified.
- The general practice is to have a 30:70 (%w/w) ratio of food waste to manure. However, research, lab testing, and/or slow and controlled introduction of new materials is strongly encouraged. See System Performance list to better understand what to watch for when introducing feedstocks.
- The amount of food waste allowable into your digester will likely be permit-limited. Review your permit and discuss with appropriate DEC contact to find out more.
- Based on lab experience and research, here are a few process parameters to moniter for process stability after adding a new feedstock: pH, total volatile acids/alkalinity ratio (TVA/Alk), methane productivity, biogas methane concentration, biogas hydrogen sulfide (H2S) concentration, and specific methane yield.
- Your system capacity should be reviewed before adding a new feedstock; the addition will likely increase the biogas production.
- Depending on the feedstock, the characteristics of the digester effluent will change. These changes should also be reviewed.
- Based on lab experience and research, we have put together a troubleshooting guidance table for when you encounter these common issues during the phase in period.
Note: Detailed information about each of these considerations is contained in the case studies and literature provided on the right side of this page.
If you have additional comments or questions, feel free to Contact Us.
Case Studies and Resources
Below are several resources, including on-farm case studies provided by Cornell University, about digester facilities currently codigesting with food scraps.
On Farm Case Studies:
Non-Farm Case Studies:
Biogas Casebook: NYS On-farm Anaerobic Digesters, Cornell University - Detailed collection of active digesters in NYS as of 2010. The report also includes lessons learned and common problems.
Food Waste to Energy: How Six Water Resource Recovery Facilities are Boosting Biogas Production and the Bottom Line, EPA (2014) - Extensive report describing the efforts by 6 Water Resource Recovery Facilities that are currently co-digesting with food scraps. Includes information such as biogas potential, storage practices, and biosolids management for each facility.
Lab Scale Co-Digestion Results with Common Substrates