Composting toilets rely on the same form of decomposition found in forests and other natural environments
Toilet composting systems differ from flush toilet systems in some very fundamental and important ways. One of the most significant differences is in the manner in which the waste matter is decomposed in these systems.
Composting toilets systems generally operate using a managed form of aerobic decomposition. This is the form of decomposition most commonly found in nature. It takes place, for example, on forest floors, where tree leaves and animal droppings are slowly converted into a stable humus.
In aerobic decomposition, organic matter is decomposed in the presence of oxygen. In this process, there will be few odors, which is an important benefit of the aerobic decomposition process when applied to toilet composting systems. During aerobic decomposition, living organisms (both microorganisms and macro-organisms such as earthworms) will feed on the organic matter being decomposed. Aerobic bacteria and fungi will break down the waste. Large piles of materials composting using aerobic decomposition will tend to generate quite a bit of heat (such as garden compost heaps), which further helps speed up the aerobic decomposition process.
Toilet composting takes this natural, usually odorless form of natural composting as its guide. Toilet composting systems are built so that they maximize the benefits and speed of aerobic decomposition, while producing few if any odors. Many toilet composting systems can break down human waste to between 10 and 30 percent of its original volume and creating a stable soil-like material called humus, which is a valuable soil additive. This humus is generally used on non-edible plants and trees in the United States, although it is widely considered safe for edible plants as well, and occasionally used to fertilize edible plants in other countries.
Flush toilets, on the other hand, rely on anaerobic decomposition. Anaerobic decomposition occurs with the absence of oxygen. Septic systems are an example of an anaerobic decomposition process at work. During anaerobic decomposition, organic matter is reduced via putrefactive breakdown, and this process usually involves strong and unpleasant odors. Anaerobic decomposition also takes place in nature, although much less commonly than aerobic decomposition. An example of a place that you might find anaerobic decomposition taking place is in the muds at the bottom of marshes, where oxygen does not have access. Anaerobic decomposition in nature is often accompanied by strong sulfuric odors. Similarly, septic and sewage systems also are quite unpleasant in terms of odor (often even more so than what is found in nature).
With aerobic based toilet composting systems, the end product (the compost) is a valuable soil additive. This mimics the process in nature, where decomposing vegetable matter on the floor of forests provide nutrients to the plants currently growing. When those plants die, they will then decompose and contribute nutrients to new plants, and so forth. Toilet composting allows human waste to enter into this cycle in a similar, productive manner which benefits the environment instead of being a waste that needs to be buried or chemically treated.
For even more information and answers to questions about toilet composting systems, please return to the Toilet Composting Home Page.
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