There are 4 factors that affect the efficiency of a composting toilet:
In optimum conditions, the composting material has the consistency of a well-wrung sponge – about 45% to 70% moisture. When below 45%, there is not sufficient moisture for the microorganisms to function, and above 70%, saturated conditions begin to develop, and oxygen depletion becomes a limiting factor.
In your BioLet the moisture content is maintained by proper ventilation, addition of proper mulch, frequent mixing of the compost and adjustment of the thermostat.
The typical temperature range for most composting toilets is 68°F to 112°F. Lower temperatures result in a moldering process that takes a significantly longer period of time to compost and therefore requires a much larger composting chamber.
Since there is a constant flow of air through your toilet the ambient room temperature needs to be maintained above 64°F during periods while the unit is in use. The toilet heater is unable to maintain sufficient heat to evaporate the excess liquid and sustain the composting process when temperatures decrease below this level.
During periods of lower ambient temperatures (late autumn, early spring, and winter) you may find it necessary to increase the thermostat to maintain the proper operating state of a moist, loamy material with no indication of liquid. Conversely, you may find it necessary to decrease the thermostat during higher ambient temperatures (late spring, summer, early autumn) to keep from drying out the material inside the toilet. (see “Adjusting the thermostat, Things to watch”)
The aerobic organisms responsible for the composting process require free atmospheric or molecular oxygen to survive. Without oxygen, they will die and be replaced by anaerobic microorganisms that will slow the composting process and generate odors. For composting toilets to work most effectively, the materials being composted should be unsaturated with liquids, and have a loose texture to allow air to circulate freely within the pile.
Although the fan in your BioLet does help with the flow of air through your ventilation pipe, it is designed primarily for circulating the air throughout the unit. Therefore, maximum aeration can be achieved by:
1) Keeping the product inside the composting chamber in a loamy consistency.
2) Proper installation of the ventilation pipe. Keep in mind that the addition of any angles in the vent pipe will reduce the airflow.
3) Ensure a good flow of air to the bathroom from the living area.
4) Proper mixing of the product inside the composting chamber (see “Use and Care”).
Carbon to Nitrogen ratio (C:N)
Microorganisms require digestible carbon as an energy source for growth, and nitrogen and other nutrients for protein synthesis. When measured on a dry weight basis, an optimum C:N ratio for aerobic bacteria is about 25:1.
A small handful of starter mulch per person per day or approximately 1 quart per person every week is a good rule of thumb to maintain a helpful C:N ratio, absorb excess moisture, and maintain pores in the composting material.
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