Composting facilities are operations that use biological processes (microorganisms) to decompose organic feedstocks such as yard debris, animal manures and food scraps. Aerobic composting uses microorganisms that prefer oxygen, while anaerobic digesters use microorganisms that thrive in low oxygen environments. Aerobic composters produce compost, while anaerobic digesters create and capture methane gas to create electricity or other fuel products. Digesters also create liquid and solid products that can be used for soil fertilizing and conditioning.
The products of composting facilities provide numerous environmental benefits. The use of compost, when incorporated into soil, can improve soil tilth and fertility; it can provide a more stable form of nitrogen less susceptible to leaching into water supplies. Compost also helps reduce compaction and increases infiltration. Incorporation of compost into soil stores carbon, helping to reduce atmospheric carbon. By capturing methane gas, anaerobic digesters avoid the release of methane to the atmosphere, a significant component of greenhouse gas.
DEQ supports and encourages composting. At the same time, DEQ is aware that, if not conducted in the proper manner, or if conducted at an improper location, composting presents potential environmental problems, most notably to surface water and groundwater.
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Regulating composting facilities and anaerobic digesters
Rules and permits
Oregon’s composting rules require permits for composting facilities and also provide exemptions from permitting requirements for certain small, low-risk composting facilities. The composting rules include permitting requirements for anaerobic digestion facilities in addition to aerobic composting facilities. Under the rules, anaerobic digesters are considered composting facilities but are issued separate anaerobic digester permits addressing issues specific to anaerobic digesters.
Composting facility rules
Reports and issues