Middletown transcript., 1914-11-21
SEWAGE DISCUSSED
Mr.. Pugha Civil Engineer Gives
Good Advise
THREE DIFFERENT SYSTEMS


of Pugh and Hubbard, Civil engineers,
Philadelphia, who lectured on the sub
ject before the Town Board last week.
Knowing that our readers would wei
come any light upon this important
question, we give the communication
in full.
Sewage is the water from commu-
nifty that has been used and made dirty
in using. 1t contains the various house
hold and other wastes, some in solution
and some in suspension. If sewage is dis
charged into cesspools, not only do they
gradually ren1er the surrounding earth
foul, but they entail continual expense
and annoyance in the removal of their
contents.
It is the function of a sewer system
to remove these offensive and unwhole-
some wastes from the homes, shops
and stores of people and discharge
them into some stream, river or other
body of water. 1t is the purpose of
OCWdSC NASDOSdI " 81 RLCPdlC llAA0
sewage before it is discharged that no
nuisance may arise or danger threaten
the body Of water or its adjacent banks.
A ton of sewage contains about two
pounds of impurities, the balance being
pure water. Of these two pounds of
impurities, about half or one pound, is
mineral, so that the task set in sewage
disposal is the removal of this minute
but offensive quantity of polluting mat
ter from the water. To one who has
not looked into the subject it seems
like an impossible task and yet an ana
logous process is familiar to everyone
manuring a field. Every manured
field is virtually sewage disposal plant,
IN which the foul smelling manure is
changed by the action of natural agen-
cies into earth and the plants raised
upon that earth. A disposal works is
merely a device for so directing the
forces of nature that they may pro
duce the desired result.
Take a glass of water and into it,
throw a spoonful of salt and a spoonful
of earth. Stir it up the salt will go
into solution; the earth into suspension.
The one substance leaves the water
clear, the other causes it to be what
we call turbid or muddy. Likewise in
sewage, part of the impurities are in
suspension. In this mixture are
myriads of bacteria, many of them
harmless, but with others capable of
causing disease. These impurities may
be removed completely or only in part,
the extent and character of purifca-
ton required in a particular case being
dependent on the nature of the water
course into which the effluent is dis
charged, and the relative volumes of
sewage and water in the stream. It is
obvious that sewage flowing into Della
ware Bay needs much less treatment
than water flowing into small rivuIet.
In any given place, publication should
be carried to the necessary point, but
not farther, since each additional step
costs money. Failure to carry it far
enough entails nuisances and in some
Instances danger.
Sewage disposal methods may be
roughly divided into three different
types of processes:
l. Removal of suspended matter.
2. Oxidizing processes, or rendering |
the sewage stable.
8. Removal of bacteria.
A disposal plant may do any one of
these three things, or two or all three
of them, depending on where the ef1u-
ent from the plant is discharged.
The skill of the engineer is devoted
to so designing the collecting system of
sewers that it will with least expendi-
ture of money, remove the sewage to
the disposal site, where it shall be
treated so that at the least ex-
pense to the community it may flow
away causing harm and injury to no
one. Shoddy and cheap construction is
not economical. The best is none too
good, but useless expenditure and poor
design calling for needlessly costly
works should be avoided.
The Sanitary Engineer has no light
task if he strives honestly and fairly to
achieve the best possible result. Rule
of thumb must be forsaken, and Of the
several alternative arrangements plan
ned and studied to see which is best
for the problem in hand. There is no
patented cure-all for sewage disposal
any more than there is in medicine.
Each case needs its own prescription,
based on known and well proved engi-
.neering and sanitary principles.
Suspended matter is removed by
screens, sedimentation by one story and
two story tanks, or at times by com
of two of these devices.
The clarified sewage is oxidized and
the organic impurities are burned out
by means of sand filters or coarse
grained filters, the latter being further
subdivIded into contact beds and sprink-
ling filters.
Disease germs are removed by disin-
fection. Space does not permita further
description Of these various devices nor
could it be well done without the aid of
-