Harnessing the Power of Microscopic Organisms
There are four general ways to deal with human excrement. The first is to dispose of it as a waste material. People do this by defecating in drinking water supplies, or in outhouses or latrines. Most of this waste ends up dumped, incinerated, buried in the ground, or discharged into waterways.
The second way to deal with human excrement is to apply it raw to agricultural land. This is popular in Asia where "night soil," or raw human excrement, is applied to fields. Although this keeps the soil enriched, it also acts as a vector, or route of transmission, for disease organisms. In the words of Dr. J. W. Scharff, former chief health officer in Singapore, "Though the vegetables thrive, the practice of putting human [manure] directly on the soil is dangerous to health. The heavy toll of sickness and death from various enteric diseases in China is well-known." It is interesting to note Dr. Scharff's suggested alternative to the use of raw night soil: "We have been inclined to regard the installation of a water-carried system as one of the final aims of civilization." 1 The World Health Organization also discourages the use of night soil: "Night soil is sometimes used as a fertilizer, in which case it presents great hazards by promoting the transmission of food-borne enteric [intestinal] disease, and hookworm."2
This book, therefore, is not about recycling night soil by raw applications to land, which is a practice that should be discouraged when sanitary alternatives, such as composting, are available.
The third way to deal with human excrement is to slowly compost it over an extended period of time. This is the way of most commercial composting toilets. Slow composting generally takes place at temperatures below that of the human body, which is 370C or 98.60F. This type of composting eliminates most disease organisms in a matter of months, and should eliminate all human pathogens eventually. Low temperature composting creates a useful soil additive that is at least safe for ornamental gardens, horticultural, or orchard use.
Thermophilic composting is the fourth way to deal with human excrement. This type of composting involves the cultivation of heat-loving, or thermophilic, microorganisms in the composting process. Thermophilic microorganisms, such as bacteria and fungi, can create an environment in the compost which destroys disease organisms that can exist in humanure, converting humanure into a friendly, pleasant-smelling humus safe for food gardens. Thermophilically composted humanure is entirely different from night soil.
Perhaps it is better stated by the experts in the field: "From a survey of the literature of night soil treatment, it can be clearly concluded that the only fail-safe night soil method which will assure effective and essentially total pathogen inactivation, including the most resistant helminths [intestinal worms] such as Ascaris [roundworm] eggs and all other bacterial and viral pathogens, is heat treatment to a temperature of 550 to 6000C for several hours." 3 These experts are specifically referring to the heat of the compost pile.
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