The primary goals of composting are pathogen reduction or elimination and a reduction in the mass of the waste. Ideally, the output of the composting process is a biologically safe, pathogen free humus, usable as fertilizer for gardens. Waste can be composted in two ways: thermophilic composting and mesophilic composting.
Thermophilic composting is high temperature composting, where the pile temperature is 50 – 75°C. The activity of microorganisms acting on the waste is responsible for the temperature increase and consequential pathogen destruction. Exposure to these temperatures for several hours (less than one day) may totally eliminate dangerous pathogens. The minimum ambient temperature surrounding the pile for this method of composting is 13°C.
Mesophilic composting is low temperature composting which relies on microorganism breakdown over time, rather than temperature, to destroy pathogens. Decomposers such as red worms and a bulking agent are added to the pile. This form of composting is slower, but more appropriate in settings with lower ambient air temperatures. The minimum ambient temperature surrounding the pile is 4°C.
The main challenge to composting in high alpine environments is keeping the pile warm. Insulation and supplemental heating (solar, electric, propane, etc.) are required. Incomplete composting may result in dangerous pathogens existing in portions of the waste, causing a health risk. Some jurisdictions require the removal of waste from the area even after being composted. This may still require removal by helicopter; however, the mass to be removed should be greatly reduced.
Composting is a biological process that requires skilled management to function well. Enough feed of the right composition is important in order to reach temperatures high enough for efficient inactivation of pathogens. Small-scale composting at mesophilic temperatures needs to be further evaluated.
Phoenix Composting Toilet System
Wells Gray Adventures, Trophy Chalet, BC
Janet's Cabin, above 12,000 feet in the Colorado Rockies
As long as the composting vessel is kept warm, waste decomposes as rapidly as it does at sea level. Photovoltaic panels charge the batteries that power the pumps, fans, and lights.
Lesser Slave Lake Boreal Bird Centre, (AB)