The evening times. [volume] (Grand Forks, N.D.) 1906-1914, 1913-10-24
Effect OF FILTRATION N THE
CORR0DNC PROPERTIES Of WATER
Question in Which Many Grand Forks Consumers are In
terested is Fully Covered by DR.. G. F. Ruediger in
Article in the Quarterly Journal.

creasing the dissolved oxygen. 1t does
not appear to US that the dissolved
oxygen can be increased by filtration
and alum c%oagulation and, hence, the
oxygen content of water need not be
considered in this connection.
In order to make absolutely sure
that the results could not be attribute
ed to a difference in the iron Of the
three pipes used, the eXperimenters
roated the pipes in different expert
ments. II, for instance, n pipe was
ment, it was filled with filtered in the
next. In addition, they filled all the
pipes with the same sample Of water
and determined the iron content at
the expiration Of forty-eight hours.
"In one Of these experiments they
say, we found a considerable differ
ence in the iron content Of the water
from the different pipes, but in the
other two the results agreed very we'll.
We believe, therefore, that there was
no appreciate difference in the ease
ed by the same sample OF water"
The Water Treatment.
All the water used in the expert
ments was taken from the Red Lake
river which furnishes the supply for
the city. The water is polluted at
several points with untreated sewage
and is. therefore. subjected to fltra-
ton at the municipal water filter. Be-
fore h%ltratie1, the water is c~oagulated
by the addition Of from two to- three
grains of alum per gallon. Owing to
the high natural alkalinity' of the. wa.
ter, no alkali is added to decompose
the water is further treated by the
addition Of from lis to LILO grain
hypochlorite Of lime per gallon.
"The following conclusions may be
drawn from the results Of lnis inves-
tigation,"' declare the chemists:
Increased by Filtration.
1. The corrosive action Of the hard
waters in North Dakota is ~appreciably
Increased by sand filtration with alum
coagulation. We believe. however,
that most of the complaints which
were made shortly after the filter was
put into operation in Grand Forks
could not be ascribed to the slight in
crease Of the corrosive action Of the
filtered water. In. all cases where the
complaints were investigated, 1t was
found that the hot water boiler, or
was one that had been in service for
was n that ha dbeen in service for
upwards Of ten years and had prob
ably been slowly %corroding for a great
many years. We found no instance
where a comparatively new pipe had
been sufficiently corroded to cause a
tleak.- = =. ....-s
lime Water Might Help.
2. In the water Investigated, we
believe that the increase in corrosive
action after filtration and alum
coagulation is due principally to the
increase in dissolved carbon dioxide.
1t was shown that, the dissolved car
bon dioxide in the filtered water is
greater than that in the unfltered wa
ter. n that the corrosive action of
the water increases when the water
is lightly charged with carbon dioxide.
the corrosive action Of the filtered
water. but 1t would seem that this
could be accomplished by the addition
Of a small amount Of lime water. Boil
ing the water to drive off the free
|CO2 diminishes its corrosive action.