Copyright Bruce Loxton No parts may be copied without express approval
Design Changes for Higher Temperature The problem with self composting toilets is not the odor (there really is none) but the time to leave the composting material to ensure all pathogens are destroyed and the waste is safe to remove. There are two primary factors that destroys pathogens in the compost. The first is The second factor is time. The lower the temperature of the compost, the longer the subsequent retention time needed for the destruction of pathogens. Given enough time, the wide biodiversity of microorganisms in the compost will destroy pathogens by the antagonism, competition, consumption, and antibiotic inhibitors provided by the beneficial microorganisms from within the compost itself. This is the relationship of the internal compost temperature and time. At Kimberley, we made a new design that could introduce a membrane heater to accelerate the heating process. This would be useful to shorten the time just prior to last use. As most people use the toilet in the morning, the target safe period is 10 hours and 55 degrees C for the composting process to produce safe to empty results the following day. The Kimberley Kruiser already had a system to accelerate this heating process: Air from the drying chalet on a Kimberley Kruiser passes into the composting toilet and is vented out through the roof. The temperature of this air will heat the base of the toilet and increase the thermophilic temperature to the maximum of 65 degrees C. As you can see from the chart, at this temperature, pathogens are destroyed in just over an hour. However for general use with Kampers and Karavans an independent membrane heater is designed to operate and achieve the same result. This design places the membrane heater between the outer base unit and an inside liner. temperature. A compost pile that is properly managed will destroy pathogens with the heat it generates.
The membrane heater is 25W. (using 2 Amps approx.) 4 hours use generates 100W of heat and uses 8 amp hours of battery capacity. You should only need this before emptying or in ambient temperatures below 20 degrees c. Image shows cut away design. The membrane heater sits between the liner and base unit.
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