Evening star. [volume] (Washington, D.C.) 1854-1972, 1901-01-05

cheney Of such plants az shown by statistics
could b improved by superior construction.
There Is more dangeS OF defective operation
in the use OF tie mechanical system than in
the slow sand system. The data as to what
could be accomplished by mechanical filters
vas not nearly so complete as that relating
cheney. though he had seen some recent
results OF mechanical filtration which show
ed 1t to be about equal to the slow sand
filter from Archaeological standpoint. He
thought there would be no difficulty in
building a mechanical plant for q city as
large as Washington. This mechanical
plant would have to be adjusted to local
conditions In the District of Columbia and
There have been a great many substantial
improvements he slid, In the last few
years. though he considered that there Is
great room for additional improvements In
their construction. He believed that In the
future there would be construction of nj
tratfon plant devised which would embody
features Of both the mechanical and the
SLOW sand systems. This had been prevent
att patent covers the continuous use of a
coaguiant, which patent, he understood,
would run out in q month. and so allow I'M
provements not possible in the past.
The Hyatt Patents to Expire.
Mr.. John P. Denison, representative OF
the company that now owns the Hyatt pat
ents, which would be involved in mechani-
cal filth alton in this country, was present,
and In reply to questions said that today
the aggregate Of water filtered in the United
States by the mechanical process was 3O0.-
ing at st. Joseph Mo-, where 100000 gal
Ions daily are filtered. He understood that
the Hyatt patents expire next month.
Mr.. Hazen, in speaking Of the efficiency
OF slow sand filter in taking out the
turbidity of The Potomac water. said he
thought the practical operation of large,
Sow sand plant might show better results
than were shown by the experiments on a
small scale made by Col. Miller. This
might be done by filterng more slowly in
times Of very great turbidity or by shut
ting off the water from the intake for a
short period. Col. Miller said, as the water
or the Potomac is quite turbid. third part
of the year Mr.. Hazen's suggestion would
not apply to that city Mr.. Hazen said
that from the tables prepared by Col. Mil
Ter he should think that the slow sand fill
ter would remove the turbidity from Poto-
mac water, though 1t might be that the
peculiar character of the particles causing
this turbidty might prevent its being made
Gear by that method.
Senator Mcmillan suggested that the
water he secures from his alum filter in his
home in Washington frequently has pecu-
liar taste. and he feared that the use of
alum on a large scale would make the
water delivered to the people of the Dis
trict unpleasant. Col Miller said the house
liiler IS SeiuO1u OF never managed SO per-
fectly as is a large filtration plant, and he
did not fear that result. He said it re-
quires the use of three grains of alum per
gallon to cause it to be in the filtered prod
uct, and the character of the Washington
water is such that that quantity will never
be necessary.
DR.. Woodward said he understood that
only two companies in the United States
sell alum, and that one of these companies
had lately been consolidated with the other.
" inonn mt in vic of not
that $4,000 worth of alum would be needed
yearly in Washington.
No Corner in Alum.
The witness replied that he did not an
ticipate that their could be any corner on
alum, as the materials from which it is
made Widespread and the process con-
nected with its manufacture was not COW
cred by any patent. a.;
In reply to a question by Senator Nc
MILAN, Mr.. Hazen said he considered the
slod-sand system more efficient in the case
of waters contaminated by sewage. while
the mechanical filter Is more efficient to
merely clearly! turbid water. If properly
managed, he thought, the alum should not
appear in the filtered water.
Mr.. Geo. w. Fuller, who has made an
extended study of methods of filtration
and various plants. testified.
For such clear water as is found in the
Hudson. he thought the slow-sand filter
Mississippi. which are extremely mud ~,
the mechanical filter is preferable. The
Potomac water resembled that of the Mis-
sissippi rather than that Of the Hudson.
He could not state positively whether tee
slow-sand system would produce satiSsac-
tory results IN altering Potomac water
until he had studied factors in the turbidtty
of that water. which he had not had an
opportunity of doing. He Thought that If
a mechanical system were installed in the
District of Columbia. built properly ard
conducted properly it would be sausfac-
tory 1t would be advisable that a plant
for the District should be constructed from
special plans made to meet the peculiar
condition of the place.
Alum Long Used in Filters.
Mr.. Fuller said alum in filtration had
been long in use and 1t had never been
shown to be deleterious on the health. 1t
had been used fifteen or sixteen years in
private houses, and he believed if it had
been Injurious to health that fact would
have been established. He could not tes-
tify to the effect that alum used in that
way was not injurious to health as he had
not undertaken to so carefully study that
question, but he based his opinion on the
fact that actual injury had not been en-
countered In bacterial efficiency he
thought as rule the degree of efficiency
in the operation of mechanical filters had
not been so great that of slow sand
filters. But he thought the fact that slow
sand filters have been operated on a large
sc ale for great cities and so had careful
attention while mechanical filters have
generally been used at smaller places where
they did not receive an equal amount of at
tention. was to large extent responsible
for the records showing more favorable re-
suits for the slow sand system.
Mr.. Fuller had tested the system of Alc-
Dougal at Cincinnati by which lime is
used as a coagulant, the trouble being that
too much lime remained In the filtered
water, which difficulty had been remeded.
though not in an altogether practicable
way by the use Of acid to remove the
trace Of lime but the matter had not been
pursued The plan Of McDougal's process
was the same as that Of mechanical filtra-
ton, except he proposed the use of lime
instead of alum, because of its cheapness.
Dr. Woodward asked If there were other
processes Of filtration that should be con-
sidered in connection with the filtration of
Potomac water and inquired about what is
known as the Fisher process" Mr.. Fuller
said that he knew that process had been
tested In Germany with water not as diff
cult to filter as is Potomac water, and
that the process had been withdrawn from
the test by its owners, which he thought
indicated the degree Of merit 1t involved
Favored the Mechanical Filter.
recess was taken, after which Mr.. Ed
mond B. Weston Of Providence, r. l., con-
sulting engineer, testified. Mr.. Weston de-
signed the plant for mechanical filtration at
East Proyidenca r l.. Norfolk ya. East