Another type of sanitary privy, known as a liquefying closet, makes use of
bacterial action as an aid to disposal. The excretions are deposited in a
tight receptacle containing water, where fermentation and decomposition
reduce a large part of the organic solids to liquid and gaseous forms.
Much of the liquid evaporates and the gases diffuse, so that the volume
of sewage is reduced materially. More or less insoluble and undigested
residue, known as sludge, gradually accumulates at the bottom of the
receptacle, which from time to time must be cleaned out. Disposal of the
partially clarified liquid and the sludge, however, involves much less
labor than would be needed to handle the untreated excrements.
Liquefying closets have been used many years with fair satisfaction.
The receptacle sometimes is a tight brick vault, but more frequently a
barrel or hogshead with one end nearly flush with the ground. Over this
is mounted the seat, sometimes with iron bars beneath to prevent accident
to small children, and the whole is inclosed in a small frame house. The
vault usually is bailed or pumped out two or three times a year.
Upon farms where slope, soil, and drainage conditions are favorable the
effluent from liquefying closets may be distributed and aerated by means
of drain tile laid in the top soil or in shallow beds filled with cinders,
coke, gravel, or stone. Figure 17 shows a simple one-chamber liquefying
closet with shallow distribution of the effluent in a stone-filled trench.
The vault or tank consists of vitrified sewer pipe, a simple and cheap
construction. Where a larger vault is required concrete or brick may be
used, the usual capacity being 12 or 13 gallons to a person.
[Illustration: Fig. 17.--Liquefying closet. _A_, Excavation about 3 feet 3
inches in diameter; _B_, 3-foot length vitrified Y branch, 24 by 4 inches;
_C_, 2-foot length of 24-inch hard burned drain tile or vitrified sewer
pipe; _D_, 4 by 4 inch Y branch; _E_, 1-foot length of 4-inch cast-iron
soil pipe; _F_, concrete bottom making water-tight seal; _G_, joints made
water tight by use of a strand of jute or oakum and rich Portland cement
mortar or hot bituminous jointing compound; H; submerged outlet; _I_,
removable strainer with openings 1/4 inch or larger; _J_, 4-inch removable
plug; _K_, 4-inch drain tile laid on good slope in trench about 15 inches
deep, ends of tile butting, joints covered with strips of tarred paper
extending three-fourths of the way around the tile; _L_, removable seat
supported by end cleats; _M_, 4 by 4 inch ventilating flue, bottom portion
removable; _N_, hinged door to facilitate bailing out sludge.]
Faults in liquefying closets are objectionable odor, clogging of the
screen over the outlet, or insufficient water in the vault to insure
proper bacterial action. A ventilating pipe should be provided extending
from beneath the seat to above the roof. The outlet pipe should not be
less than 4 inches in diameter, and the mesh of the screen should not be
less than one-fourth inch. The contents of the vault should be diluted
with water at intervals, depending upon the number of persons using the
closet and the rapidity of evaporation. Dilution may be effected by
pouring in 1 or 2 gallons with a pail, or a small pipe may be led from the
eaves trough of the closet to the vault. The effluent may be light colored
and apparently inoffensive, but it still is sewage, and therefore the
distributing tile never should be laid in the vicinity of a well or spring.