The Columbia herald. [volume] (Columbia, Tenn.) 18??-1935, 1904-10-21
HOW ST. LOUIS WATER SUP
PLY Is PURIFIED.


st. Louis for purifying its water
supply:
Until recently this city has only
been supplied with river water i'm
proved by ordinary sedimentation.
Prior to the present year. the water
was allowed to stand in large sub
sidence basins for periods VARYING
from twenty-foui to seventy two houTs.
where a large amount of the sus-
pended matter was deposited. but the
finer clayey particles, the colorlng
matter and many of the bacteria Ie-
manned.
s'It has been known for long time
that sulphate of iron and milk of lime.
when used properly, will collect fine
particles of mud, render insoluble col
orine matter and cause q rapid sub
sidence of suspended constituents. but
these facts were not put into practical
use in the publication of muddy
stream until last spring, when the
water used here was treated with these
substances on a large scale.
hThe st. Louis water supply is
taken about fifteen feet from the shore.
opposite Chain of Rocks. 1t flows by
gravity through ninefoot conduit to
a receiving gallery at the low service
pumping station. opposite the intake.
From this gallery the water is lifted
some eighty or rinety feet, depending
on the stage of the river, by pumps.
and discharged into the open end of
the distributing conduit. AS the
water flows from the river to the
pumps it receives in solution about one
gram of sulphate of iron to the gallon,
and as it is discharged into the open
end of the distributing conduit. after
leaving the pumps, it is further treated
with about six grams of milk of lime
to the gallon. The amount of iron
and lime, however, depends upon the
condition of the river and varies
through considerable range. Daily
tests are made of the water and the
amount of coagulants governed thereby.
LAS soon as the sulphate of iron is
added to the water it acts upon the
carbonates OF hme and magnesia dis
solved therein and forms a preclpitate
coloring matter. entraps the bacteria
and gathers together suspended par
ticles of clay. but ready subsistence
does not take place. Milk of lime acts
IN much the same way. 1t makes up
the tree carbonic acid, unites with the
soluble blcarbonate of lime and allows
" to preclpitate az normal carbonate.
It also converts the bicarbonate of
fnagnesia successfully into a normal
carbonate and then into hydrate of
magnesla, which preclpitates. Neither
the lime nor the magnesium com.
pounds will subside readily, but when
kno h.,a, - >xxcIx, odd n
the water and the amount of milk OF
lime is properly governed by cheml-
cal tests. subsistence takes place within
a few minutes, and the water becomes
quite clear. free from coloring sub
stances, and has very large per-
centage of its organic matter and
bacteria removed. And the expense
for labor, chemicals. power. etc., to
do this work. averages about So % per
million gallons of water treated.
"These changes are effected in six
settling basins, joined side by side.
each 825 feet long by 400 feet broad,
and having an average depth of fifteen
feet and capacity of 81.0OO.0OO gal
Ions. Under ordinary conditions OF
operation, the water after being
treated with the chemicals flows into
the nearest settling basin; from this
It passes over weir into the second
basin, and SO on until it leaves the
sixth basin through gate into con-
duit which carries it to the Baden and
the Grand avenue pumping stations.
where 1t is distributed to the city.
Much of the mud and other i'm
puritles are precIpitated in the first
settling basin and the water is greatly
improved in appearance. The weiis
assist in the precipitation and also
mriate the water. so by the time it
reaches the third or fourth basin it is
quite clear and satisfactory for drink
ing. The basins are cleaned every
few weeks and are connected with by
passes, 80 that any one can be taken
out of service while being cleaned
without affecting the others.
THE purified water as delivered to
the city has slight opalescence. due
to trace of magnesium hydrate and
fine clay, hut the amount of suspended
matter is ordinarily less than half a
part per million of water treated and
the water is entirely tree from iron.
The organic matter is removed by this
process SO thoroughly that, the albu-
mfnoid ammonia which is usually
about 1. 200 parts per 1000. 600 in the
raw wafer IS only about .160 part in
the purified water. while more than 80
per cent, of the bacteria disappears.
The water thus delivered to the
city 10 gEAat improvement on what
was, formerly consumed. and 1t was
foftunate for ST. Louis that the process
was discovered and put into use in
time Tor the Louisiana Exposition. as
the city can now boast of having a
water supply that compares favorably
IN appear ance and purity with the
water Of other IIver cities, while the
typhoid rate during the last six
months has been very small.
'sThe above mentioned process is, of
course only in its experimental de.
velopment. and may be greatly changed
before permanent plan is adopted,
but II has produced such wonderful
results here that IL is worthy Of con-
sideration in any preliminary expert
mental river water investigation.
We reproduce the above. for sugges-
tion to our City Fathers. Nearly half
the time the water furnished by the