MIL-HDBK-1005/16
6.5
Waterless Toilets
6.5.1
Humus "Composting" Toilets. The U.S. Forest Service
and several manufacturers have developed several types of humus
toilets (see The Composting Option for Human Waste Disposal in
the Backcountry, Fay and Walke, 1975, and Utilization of
Earthworms and Micro-organisms in Stabilization and
Detoxification of Residue Sludges from Treatment of Wastewaters,
Hartenstein and Mitchell, 1978). All humus toilets are
watertight and depend upon microbiological decomposition for
their reduction in volume and their destruction of pathogens.
The patented "Clivus Multrum" is the forerunner of the modern
composting toilet. The Clivus Multrum essentially involves only
a toilet seat and a large sloped container with floor tilted at
33 degrees. This allows excreta to aerate and to gradually move
to the base of the chute toward an access hatch. Excess moisture
evaporates through a 6-inch (150 mm) roof vent. The system
depends upon the user depositing peat moss or soil into the chute
periodically. Kitchen waste, toilet paper, shredded paper or
other biodegradable waste should also be added regularly.
After about 3 years, and once each year thereafter, a
small amount of "humus-like" compost may be removed from the
access port and used as fertilizer. Humus toilets are simple,
very efficient, and easy to install. However, they are
moderately expensive, are space intensive, and also require a
slope or must be installed on the second floor. They should be
seriously considered in mountainous terrain or when buildings are
built on slopes. Smaller box-like units have been designed and
installed in Scandinavia and England but these require an
electric heater (see New Options for a Sewerless Society, Liech,
1976.)
6.5.2
Chemical Toilets. Chemical toilets are usually
manufactured of fiberglass and are inexpensive to install and
maintain. The chemicals used have a high pH and have been known
to cause minor burns. A fragrance is usually added to mask odors
because no biological degradation occurs between cleanings.
After cleaning, pumper trucks usually transport the treated
wastes to a sewage treatment plant. Chemical units are less
desirable than humus units because they require not only greater
energy costs but also constant maintenance and hauling to a
treatment plant.
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