Under average conditions a man discharges daily about 3-1/2 ounces of
moist feces and 40 ounces of urine, the total in a year approximating 992
pounds.[1] Feces consist largely of water and undigested or partially
digested food; by weight it is 77.2 per cent water. 2 Urine is about 96.3
per cent water.[2]
[1] Practical Physiological Chemistry, by Philip B. Hawk, 1916, pp. 221,
359.
[2] Agriculture, by F. H. Storer, 1894, vol. 2, p. 70.
The excrements constitute but a small part of ordinary sewage. In
addition to the excrements and the daily water consumption of perhaps
40 gallons per person are many substances entering into the economy of
the household, such as grease, fats, milk, bits of food, meat, fruit,
and vegetables, tea and coffee grounds, paper, etc. This complex product
contains mineral, vegetable, and animal substances, both dissolved and
undissolved. It contains dead organic matter and living organisms in the
form of exceedingly minute vegetative cells (bacteria) and animal cells
(protozoa). These low forms of life are the active agents in destroying
dead organic matter.
The bacteria are numbered in billions and include many species, some
useful and others harmful. They may be termed tiny scavengers, which under
favorable conditions multiply with great rapidity, their useful work
being the oxidizing and nitrifying of dissolved organic matter and the
breaking down of complex organic solids to liquids and gases. Among the
myriads of bacteria are many of a virulent nature. These at any time may
include species which are the cause of well-known infections and parasitic
diseases.