The Pacific commercial advertiser. [volume] (Honolulu, Hawaiian Islands) 1885-1921, 1908-12-31

! system, to filter 100000 gallons G
water, would cost tor construction
the neighborhood of from $250,0U0
, 100000. The entire artesian system
, as above outlined, would cost approx
mateIy 100000 Against the filtratio
plan, besides the original cost, Nigh
be added that it would be expensive t
operate. as it would have to be il
charge of thoroughly competent opera
tors, assisted By chemists, etc, SO tina
constant analyses OF the raw and eff
fluent waters could be made. Without
Such assistance, filtration would result
/ in worse conditions than raw waters
Further, all the sands necessary for the
I filters would have to be imported from
/ California, whereas, with the proposed
artesian system, as outlined above, with
new pumps, we would not require any
employed at present, as they would be
housed under the same roofs as at pres
emit occupied Items of cost. as given
by Expert Civil Engineer Rudolph
Herring, was over $2G per million gal
Ions. by the method of filtration, but
probably the cost could be reduced con-
siderably, as since that time methods
have improved.
In reply to my question as to the dis
IL
its use for power purposes, superin-
tendent Campbell stated that there are
three channels of Nuuanu valley water
that converge into Nuuanu valley, viz.
stream, main Nuuanu stream,
and its branches. During ordinary
weather these streams are full, and
there is more or less drainage from
cesspools and yards, etc., and they be-
come a catchment basin. The idea is
to utilize the waste waters and to keep
a constant and steady stream of water
flowing through the main channel This
would also stop mosquito breeding. 1t
might also be used for irrigation of |
upper lands.
Continuous Filters and Their Con-
struction.
Filtration of water consists in pass
ing it through some substance which |
retains or removes some of its impuri- |
ties. In its simplest form, filtration |
is straining process and the results
obtained depend on the fueness of the |
strainer, and this in turn is regulated |
by the character of the water and the |
uses to which it is to be put. Thus |
in the manufacture of paper an enOr-
nous volume of water is required, free
from particles, which, if they should |
become imbedded in the paper, would |
injure its appearance or texture. OBJ |
viously for this purpose the removal
Of the smaller particles separately in
visible to the unaided eye, and thus
not affecting the appearance of the /
paper, and the removal of which would
require the use of a finer filter at in
creased expense, would be a simple
waste of money. When, however, a
water is to be used for a domestic
water supply and transparency is an
object, the still finer particles which
would not show themselves in paper,
Dut which are still able, in bulk, to
render a water turbid, should be as
FAR as possible removed, thus neces-
stating finer filter; and when there
s reason to think that the water con
aims the germs of disease, the filter
must be fine enough to remove with
those organisms SO extraor-
linarily small that millions of them
nay exist in glass of water without
visible tmbiaity.
1t is now over a half century since
he first successful attempts were
made to filter public water supplies,
md there are now hundreds of cities
With clear, healthy, filtered water. In
act it might be said that so universal
lbs bttu Aut u'liidui luI pure NdltE |
hat no city with any pretensions or
growth has failed to avail
tself of this or other means of fur
fishing a purer water supply. While
he details of the filters used in differ
mt places present considerable varia-
ions, the general form is everywhere
he same. The process is as follows:
The raw water is. taken into a settling
'asin, where the heaviest mud is al
owed to settle. In the case of lake
md pond waters the settling tank is
dispensed with nut it is essential for
urbid river water, as otherwise the
mud clogs the filter too rapidly. The
clarified water then passes
o the filter, which consists of a hori-
.ontal layer of rather fine sand sup
ported by gravel and underdrained, the |
whole being enclosed in suitable bas- |
N or tank. The water in passing |
through the sand leaves behind upon |
he sand grains the extremely small |
PARTICLES which were too fine to settle |
nut in the settling basin, and is quite !