Montour American. (Danville, Pa.) 1866-1920, 1909-05-20
PUR|FICAT|ON
Of Sewage

tlOu Vi bne seWaR5 ulsposal pldnb De
ing constructed at the hospital for the
insane at this place. The description
will be perused with 20 little interest,
as there is great deal about a sew.
age disposal plant that is not under.
stood by the general public. Our read.
ers will be glad to learn by what me-
thod sewage publication is accom-
plished.
The object in treating the sewage as
described is of course to take out of
the waste water the Impurities which
have been put in it. The removal of
these impurities is accom- plished in
several ways, either by keeping the
sewage in quiescent state, in large
tanks or vats, which allows much of
the matter in suspension to settle in
the bottom, or collect on the top of the
water after which the clearer water
may De drawn on or again the sew
age may be passed through filter
something.lik water filter which
holds back the impurities Experience,
| however, has shawn that the most
practicable method is a combination
of settling and filtration and this is
the scheme adopted at the Danville
! hospital.
Sewer systems in towns generally
provide for taking both storm water
and house drainage. This WAS the
scheme at the hospital and besides. the
sewers were so constructed that all the
sewage could not be taken to one
point, which is necessary for a sewage
disposal publication plant. 1t became
necessary to construct new system
of sanitary sewers which will dis
charge in we'll near the barn. In
this we'll are set automatically con-
rolled electrically operated sewage
pumps which Will force the sewage for
distance of 1900 fees to the new plant
in the fields above the farmers house.
Tie pumps are set in triplicate to
make action certain al all times, and
are so connected electrically that when
the sewage rises to a fixed height in
the we'll. an automatic switch will be
thrown in by means OF float and one
of the pump will start; aud when the
well becomes empty, it will again
automatically stop.
After the sewage.reaches the plant
it first passes through a screen cham
ber TO take out coarse material, and
then it passes very slowly through
three large settling tanks each 50 feet
long, s feet deep and 16 feet wide In
the tanks perhaps thirty per cent. of
the suspended matter settles out and
the clearer water flows on to the fit
er. Provision is made for cleaning the
settling tanks and drawing off the
heavy matter or sludge on a sand fit (
er.
The floor of the settling tanks Is /
higher than the top of the filter. The (
area of the filter is little less than
one quarter of ansacre; its dimensions
are length ll5 feet, width 81 feet, ,
depth feet. The filtering material is /
of pebbles from one to four inches in .
size. Terra Gotta pipe underdrains
are laid under the .fltering material.
These draw the water from the body
of the filter to drainage channels on
the side. The water from the settling
tanLe Houc 6rct into q tank hoIdInn
$500 gallons and as this'tank fills up,
syphon set in it discharges the sewage
on the filter through "a spraying noz-
zles under a varying head of three and
one half to five feet. With these noz-
zles, the water is sprayed on top of the
filter bed, the operation being almost
exactly the same as IL it were done by
and with an ordinary garden sprinkl-
ing pot. This type of filter is known
as 'sprinkling" or percoIating"
filter. The water after 1t falls ON the
stones or pebbles slowly trickles down
through the body Of the bed leaving
the impurities in the bed. Water from
this filter will not be quite clear and
1t is passed second time through a
settling tank and filtered second time
through sand TO remove all impurities,
Or treated with disinfectsnt to make
sure that every disease breeding germ
Is killed.
This scheme of sewage treatment is
known as the bacterial or biological
system. 1t has been developed within
The last 20 years, and the greatest ad-
vance has been made within the past
ten or twelve years. The type of plant
under construction at the hospital was
first used on an extensive scale in
England, where there
are about 30 acres of sprinkling filter
beds. Recently a few such plants have
been constructed in this country at
Ohio, Washington and Read
ing, Pa. This type of filter is also us
I'D at Mount Alto Sanitorium and will
be constructed at the State hospitals
at Wernersville, Norristown and Polk.
1t should be borne in mind that a
plant of this kind must be put in
,harpe OF competent and reliable
man whose sole duty is to see that its