[Peter]

Comparing landfills and anaerobic digestion of a mechanical separated organic fraction, anaerobic digestion captures much more of the potential methane emissions, conserves limited landfill space, and in some cases can recover soil nutrients.

Landfills only capture methane after cells have been closed. When a new cell is being filled the food waste is degrading (some aerobically, some anaerobically) releasing emissions to the atmosphere. At the same time landfill space is limited and permitting new landfills can take a long time due to the environmental risks. That being said, landfills aren’t going anywhere and will remain an important part of MSW management and the biogas landscape even if 100% of organics could be diverted.

While digestion of MSW is not always the best available option, there are several pretreatment and digestion technologies that have been used effectively. The anaerobic digester technology that will be most effective at treating a mechanically separated organic fraction will depend on the characteristics of the local MSW waste stream. Characteristics will be substantially different if there are organics diversion, paper recycling, or glass recycling programs in place. The design decisions will also be influenced by local prices for disposal of residuals, water, and energy.

If you are interested in MSW digestion and feedstock characterization you can reach me at peter.quosai@azuraassociates.com.