One of the more interesting anaerobic processes is the breakdown of municipal solid waste in landfills. I grew up not far from what we called Rumpke Mountain, the sixth largest landfill in the United States. Landfills typically require venting because anaerobic processes consume the solid waste within the landfill, producing methane and carbon dioxide gasses. If not vented properly, the gas can build up causing an explosion. Many have tried capturing the gas during venting to make the methane usable.
I recently learned how landfill waste can be processed in a bioreactor. Waste Management is working on testing new bioreactor-based landfills. In a bioreactor landfill, the landfill will degrade organic materials by increasing the moisture level of the waste. Assorted microbes consume the waste, basically composting the organic material. Inorganic material is left behind, but it substantially cuts the volume of the waste. At this stage, WM is still looking into the qualities of aerobic, anaerobic, aerobic-anaerobic, and facultative processes to determine their relative effectiveness.
The neat thing here is that WM is trying to change the way landfills work from, well, dumps, to “waste treatment” facilities. In a sense, this is a solid waste parallel to the wastewater stream. From their perspective, they would eliminate the risks associated with dumping raw waste into a landfill and the potential for leaks. Further, WM is researching whether it is possible to retrofit existing landfills to fit this model.
This is a great way to reduce the effective volume of solid waste produced if it can be done effectively and at scale.