Composting Toilets

Replacing an illogical practice
with an ecological solution

Composting toilets are becoming more and more acceptable and popular with people in all types of situations. Composting toilets are finding their way into mainstream homes due to tightening wastewater regulations, awareness of pollution, and compatible grey-water systems. Property owners are also reconsidering this alternative due to skyrocketing sewer rates and holding tank pumping costs.

Possibly the most important change in the public's reception of composting toilets is that they can be coupled with micro-flush toilet systems. This feels more traditional for many toilet users – some are put off by the 'black hole' concept of the typical composting toilet. The extra water from these toilets must be treated by evaporation, disposal, or utilisation.

Composting toilets usually require permits from town, county, or state officials and the ease of permitting them varies widely in different countries.

History

From an early age we are accustomed to relieving ourselves in the privacy of small cubicles. This has not always been the case. In the early hunter-gatherer cultures and tribal societies, disposal of human waste material was through dispersal. We assume, they paid careful attention to protection of their drinking water sources. This dispersal method was successful because of extremely low population densities. However, as populations increased issues of disease and pollution became important. Concentrating waste material in latrines poses problems. Access to the waste material by insects and rodents raise the danger of disease and therefore limits the use of latrines in populated areas. Water-borne sewage systems in the early days involved the use of cesspools, which required the unpleasant talks of emptying when full. There was also increased risk of ground and surface water contamination with this method. The use of cesspools has gradually given way to the use of centralised sewage collection and treatment facilities, but at an enormous economic and environmental cost to communities worldwide.

Sweden's extremely rocky soil conditions prompted research and development that led to the evolution of composting toilets as they are today. The rocky conditions prevented the installation of the typical water borne waste transport system. Septic tanks were also not practicable because of the lack of soil absorption capacity. The early models of composting toilets, first appeared in Sweden in the 1930s.

Types of composting toilets

Most composting toilet designs are based on either 'batch' or 'continuous' composting. With batch composting there are more than chamber and chambers are rotated as they become full. In this way, the older or finished compost is not contaminated by the new waste. In some systems the full chambers can be removed for emptying.

'Continuous' composting uses only one chamber for composting. In this system, fresh waste is continually deposited at the top of a chamber, and finished compost is removed from the other end of the chamber.

Composting toilets can be either 'self-contained' or 'central' systems. The composting reactor is separate from the toilet bowl in the central system, often in its own enclosure to the side of the building. These central systems are usually the choice of year-round homes and facilities that have multiple toilets.

The compatible micro-flush toilets use either a small amount of water to move the waste, or they use a vacuum similar to those on airplanes and trains, or they may use foam.

The composting process

Wastes decompose over a bed of carbonaceous materials (peat moss, wood chips, sawdust, chopped leaves, grass clippings or other loose organic materials) in a ratio of approximately five parts organic material to one waste matter.

The composting toilet generates carbon dioxide and water vapour. These are vented from the chamber and the remaining valuable composted material can be used as a soil amendment for shrubs, trees, grass, etc.

Maintenance of composting toilets

The prospect of maintaining composting toilets puts many prospective purchasers off. An inoculating material needs to be placed in the base of the new and unused composting chamber. This provides the 'friendly' bacteria to start the composting process.

After each use, add at least on cup of 'dry flush' organic materials eg peat moss, wood chips, sawdust, chopped leaves, grass clippings, shredded newsprint or even dirt. Less absorbent materials and therefore not highly recommended are rice hulls and straw or hay.

To insure better decomposition don't add substance that will reduce the acidity such as lime or ashes.

The composter needs to be kept free of foreign objects, meat scraps, and materials that do not easily decompose.

Keep the composter chamber free of excess fluids. Harmless human urine is rich in nitrogen and can be safely recycled in the garden. Containers of sawdust and urine make excellent lettuce bedding.

Occasional levelling of the material with a pitchfork is required in some of the composting systems.

Benefits of composting toilets

Composting toilets have many advantages: