COMMERCIAL COMPOSTING TOILETS
Commercial composting toilets have been popular in Scandinavia for some time; at least twenty-one different composting toilets were on the market in Norway alone in 1975.9 One of the most popular types of commercially available composting toilets in the United States today is the multrum toilet, invented by a Swedish engineer and first put into production in 1964 (see Figure 6.4). Fecal material and urine are deposited together into a single chamber with a double bottom. The decomposition takes place over a period of years, and the finished compost gradually falls down to the very bottom of the toilet chamber where it can be removed. Again, the decomposition temperatures remain cool, not usually climbing above 32°C (90°F). Therefore, it is recommended that the finished compost be buried under one foot of soil or used in an ornamental garden.10
Because no water is used or required during the operation of this toilet, human excrement is kept out of water supplies, conserving water. According to one report, a single person using a Clivus (pronounced Clee-vus) Multrum (see Figure 6.5) will produce 40 kg (88 lbs) of compost per year while refraining from polluting 25,000 liters (6,604 gallons) of water annually.11 The finished compost can be used as a soil additive where the compost will not come in contact with food crops.
A 1977 report issued by Clivus Multrum USA analyzed the nutrient content in finished compost from seven Clivus Multrum toilets which had been in use for 4 to 14 years. The compost averaged 58% organic matter, with 2.4% nitrogen, 3.6% phosphorous, and 3.9% potassium, reportedly higher than composted sewage sludge, municipal compost, or ordinary garden compost. Suitable concentrations of trace nutrients were also found. Toxic metals were found to exist in concentrations far below recommended safe levels.12
If a multrum toilet is managed properly, it should easily be odor and worry-free. As always, a good understanding of the basic concepts of composting helps anyone who wishes to use a composting toilet. Nevertheless, the multrum toilets, when used properly, should provide a suitable alternative to flush toilets for people who want to stop defecating in their drinking water. You can probably grow a heck of a rose garden with the compost, too.
Inexpensive versions of multrum toilets were introduced into the Philippines, Argentina, Botswana, and Tanzania, but were not successful. According to one source, "Compost units I inspected in Africa were the most unpleasant and foul-smelling household latrines I have experienced. The trouble was that the mixture of excreta and vegetable matter was too wet, and insufficient vegetable matter was added, especially during the dry season." 13 Poor management and a lack of understanding of how composting works will create problems with any compost toilet. Too much liquid will create anaerobic conditions with consequent odors. The aerobic nature of the organic mass can be improved by the regular addition of carbonaceous bulking materials. Compost toilets are not pit latrines. You cannot just defecate in a hole and walk away. If you do, your nose will let you know that you're doing something wrong.
Besides the Scandinavian multrum toilets, a variety of other composting toilets are available on the market today. One manufacturer claims that over 200,000 of their composting toilets have been sold worldwide. The same manufacturer produces a fiberglass and stainless steel toilet which consists of a drum under the toilet seat or under the bathroom floor into which the feces and urine are deposited. The drum is rotated by hand in order to blend the ingredients, which should include food scraps and a carbon material such as peat moss. The toilet can come equipped with an electric heating system and an electrical fan ventilation system. The compost, produced in small quantities which are removed by pulling out a drawer beneath the drum, is said to be suitable for garden purposes. Some of the models require water as well as electricity (although some require no electricity or water).14
Other composting toilets cost upwards of $10,000 or more, and can be equipped with insulated tanks, conveyers, motor-driven agitators, pumps, sprayers, and exhaust fans.15 According to a composting toilet manufacturer, waterless composting toilets can reduce household water consumption by 40,000 gallons (151,423 liters) per year.16 This is significant when one considers that only 3% of the Earth's water is not salt water, and two-thirds of that freshwater is locked up in ice. That means that less than one percent of the Earth's water is available as drinking water. Why shit in it?
Source: The Humanure Handbook. Jenkins Publishing,
PO Box 607, Grove City, PA 16127. To order, phone: 1-800-639-4099.