A composting toilet is a system that collects human waste and then processes it by aerobic microbial activity, which decomposes it and kills off potentially hazardous substances. Composting toilets are environmentally friendly, do not require water or sewage treatment, and produce an end-product that is ideal for fertilizing trees and landscapes. Composting toilets are more carefully implemented than pit toilets or pit latrines, which are essentially just waste ditches that can pollute groundwater.
A composting toilet can be built indoors or outdoors, and the designs range from simple, do-it-yourself kits to more expensive and elaborate manufactured systems. Users simply apply small amounts of absorbent materials, such as peat, sawdust, or other carbon-laden products after each use. Doing so will soak up superfluous fluids, and aids in aeration for enhanced aerobic action. Composting toilets typically incorporate vents which run upward and outward from the device, and these act to circulate air and eliminate odors. Fans may also be installed to increase air flow.
Remote composting is a type of composting toilet system where collected materials are manually transported to a composting bin that is established to process yard and kitchen waste. Another system is continuous composting, in which waste material decomposes in the same receptacle where waste is deposited. Because the material is not moved as in remote composting, microbial activity is unimpeded, and the decomposition takes place faster as heat builds up. Batch-composting is another type, which employs multiple composting receptacles that are alternated: One processes material as the other collects new waste. Finally, dry composting toilets are those that separate urine from feces, which diminishes moisture and the nitrogen content of the compost material.
Besides the environmental benefits, there are other advantages of composting toilets. Because no water is required for composting toilets and they employ aerobic activity to break down waste, they are an ideal option in areas that lack access to running water. Also, less water usage means less stress on freshwater supplies, and a lower household water bill. Composting toilets are relatively simple to install, as no plumbing, septic tank, or sewage treatment is required. In addition, local soils maintain their respective fertility, as nutrient-dense humus is returned to the ground. Finally, compost toilets can be installed in both rural and urban environments, depending on local ordinances.
Still, there are some drawbacks of composting toilets, as they require proper commitment, attention and maintenance. The system receptacles need to be emptied periodically, anywhere from every few months to every few years. Plus, the systems may be aesthetically unappealing, especially those which allow excrement to remain visible. All units require periodic cleaning, which may be unpleasant if the system is not functioning properly.