The evening times. [volume] (Grand Forks, N.D.) 1906-1914, 1912-03-07
F|lTER|NG PLANT To
Be IN COMPLETE
OPERATION
All Parts Will Be Open For
Public Inspection at Open
House Tonight

Open house will be the order at the
city filtration plant tonight and per-
sons interested in seeing how the filter
works will be shown through by
experts who will explain the plant as
they go.
The new filter plant is what. is
known as a rapid sand filter. It con-
sists of a building 35x7s feet and two
stories high. built in the south end of
what was formerly a sand bed. The
remaining portion occupied by the
sand bed is divided by concrete walls
running lengthwise into two settling
basins,
The water from the Red Lake river
enters a trough-like basin 24X124 feet.
from there the water goes into a gate
chamber where the coagulent is added
and which has provisions 80 that the
water may be utrned into either of the
two large settling basins.
Have Big Capacity.
+ The large basins are 61x140 feet in
size and have a capacity Of 100000
gallons each. The water enters from
either or both of these big basins into
the filter building proper and is con-
trolled by gates 81 hat the water will
now but n or all four units, which
each have a capacity Of 500. 900 gall
Ions every twenty-four hours.
." ASOI toOl1l ClllCI0u Ill LI0 UullOs
Ing from the street contains the 1,OOO,-
700 centrifugal wash pump and root
oloWer or air compressor. A. stairway
leads to the second floor which con-
tatns the appliances for operating the
filter and controlling it's operation;
also the Office room and room for stor-
ing and mixing the coagulent.
Settling Is Important.
In the ftltering operation. which Is
very simple. much depends upon the
settling of the water. The trough
like basins take out most of the mud
when the water is riley and are easily
cleaned. They are SO arranged that
either n may be placed out of COM
mission for cleaning purposes.
The coagulent acting and rcacting
with the line or hardness of water
forms an insoluable jelly-like sticky
flake hat gathers up quantities of fine
SIT and bacteria in the water and car
ries 1t to the bottom Of the larger
basins. These basins can be used al
ternately and cleaned.
When h water reaches the filters
it Will be fairly clear except that it
VII! contain some of the jelly-likc per.
ctpitate that has not become settled
and which will lodge on top of the
sand and in reality form the princi-
pal altering medium. taking out the
SIAS I'LL bdClcIld.
Thirty Inches of Sand.
The water OF the beds sinks through
about thirty inches of special quartz
sand and Is collected at the bottom by
seven brass %strainers. imbeded in con.
crete and flows through a device
which controls the rate of flow for
filter into a 1000, 900 gallon clear
water basin.
When the coating on top of the sand
becomes so thick that the rate of
hlteration Is diminished the wash
pump is started and filtered water is
forced up from the bottom of the
sand together with compressed air. the
sand being thoroughly washed and
secured and the dirt washed into the
sewer. About five minutes is taken
To- each washing operation Of each
PED. NO sand is wasted during the
and the filters are imimedf-
ately ready for another run. -.
The chief mechanism of the filter
consists OF gates. controllers and ap-
p!iances for insuring a uniform rate of
liberation and the washing Of the
beds. ~
Tho coagulent used in Grand Forks
sulphate Of aluminium. which forms
upon being mixed with
OF lime in the water. giving the alum
mum hydrate jeIty-like t~asteless sub
which in nature forms the
OF all clays. II is a substance
used. and necessarily. where the wa
ter contains much fine silt and ia no
a peculiar feature of the rapid sand
The use Of hypo-chloride ozone or
any other germicide is not an essen
tial feature Of the plant although used
from time to time. and is used
extensively ali owe the country where
the water is much contaminated with
sewage and then irrespective Of what
OF hitter or other means Of water
Is employed.