When an anaerobic digester processes organic material, it produces a gas (biogas) plus liquid and solid digested material. Those liquids and solids are called digestate.
Raw or whole digestate produced by a biogas system is physically and chemically different from the organic input material used to produce it.
Key Changes To Organic Materials From Anaerobic Digestion
- Often heterogeneous, hard to obtain sample for accurate characterization or analysis
- May contain bulk physical contaminants such as packaging or non-organic physical contaminants
- Many contain and facilitate growth of pathogens, weed seeds
- Highly unstable, putrescible (odors, VOCs, methane)
- Nutrients predominantly in the organic form, lower plant availability
- May be bulky, low transport efficiency
- Homogeneous, highly representative sampling for accurate characterization
- Physical contaminants largely removed in pretreatment
- Substantial (>90%) reduction in pathogen levels, and kills viable weed seeds
- Substantial stabilization and reduction in odor, VOC and methane potential
- Nutrients predominantly shifted to inorganic form, greater plant availability PLUS additional micronutrients resulting from the die-off of the microorganisms and when used, added micronutrients.
- Densified, higher transport efficiency
Learn more about anaerobic digestion and biogas systems
- How biogas systems work https://www.americanbiogascouncil.org/biogas_howSystemsWork.asp
- What is anaerobic digestion https://www.americanbiogascouncil.org/biogas_what.asp
- Biogas 101 fact sheet https://www.americanbiogascouncil.org/pdf/ABC%20Biogas%20101%20Handout%20NEW.pdf
- Biogas Project Profiles https://www.americanbiogascouncil.org/biogas_projectProfilesNEW.asp
- Map of Operational Biogas Systems https://www.americanbiogascouncil.org/biogas_maps.asp