The Providence news. (Providence [R.I.]) 1891-1906, 1896-04-27
WATER FILTRATION.
William B. Bull, Water Works Ex-
pert, Writes TO the News.
Tells About the Extensive Experiments
Carried on al Louisville.

THH NEWS has received a very interesting
letter from william h. Bull president Of the
water works n: Quincy, i'll.
1t Is relative TO the very interesting matter
OF water filtration and. contains valuable IN
formation concerning the extensive expert
monts carried ON at Louisville, and which
resulted in the decision of all the experts In
favor Of mechanical filtration. The letter IN
as follows:
To THE EDITOR OF The PROVIDENCE NEWS.
sIR-In view OF the agitation In your city
over an improved and purined water supply,
many OF your readers may he interested 20
know what Is being done by Western cities In
the same direction, and especially ny Louis
vile, where the water supply Is drawn from
iho ONO River. and me "Unoltions ior tnat
reason are somewhat similar TO those OF FRO
vidence.
have read With much interest the report
OF the joint committee on the city enginees,s
departinent recommending the system OF nj.
tration To your city, and am not surprised AT
their conclusions that the Pawtuxet water
requires filtration, for they are unquestion-
ably advising wbat will very soon DO the
universal practice in all large cities wher3
tLero Is doubt as TO the purity OF the pnoIic
water supply.
There are two methods OF fltration Of
water in largo volume: one ~ the sand he'd"
method, as generally practiced In Europe,
and to ~ Iinited extend in this country, and
which is known to Re an efficient means Of
water publication. Under this Dystem are
large basins several acres IN extent and In
those basins are constructed hlters CT gravel
and sand. through which the water slowly
percolates, giving an eftuent OF unquestioned
purity.
In localities Of n certain winter tempera.
ture, namely, those where the mean January
temperature is below 82 degrees, tho forma'
ton OF ice on the surface Of such tltsr bsds
requires them TO be covered ny roofs, prefer
nbiy OF vaulted masonry, and as Providence Is
much north Of the line for which the hest
authorities advise that filters SO constructed
shall be rooted, IL ~ probable that roofing tho
filters may be advised for your city N sand
bed 6lters should ultimately be adopted.
|. The great objection TO the adoption OF the
above method OF filtration Ia Its enormous
first cost. and IL is In reference to n plan OF
nltration costing much less to install that
write you.
The plan referred to Is known as 'mechani.
CAL fltration. where the hltering material
is contained In large tanks Of steel or wood,
from IL TO "a feet in diameter and In which
the hltering bed OF sand u washed and purf-
fed "a often as ID becomes foul. The rate OF
filtration IN mechanical filters Is almost so
times az rapid as in the sand-bed hlters first
referred TO. and hence they may be much
mere compact In construction. and more
economical TO purchase than the sand red
filters referred &, IN the report OF your com.
mittee. In word. the cost OF q mechanical
filter plant suiiab for the publication OF the
water supply Of your city eau be erected for
not to exceed one-haif the necessary cost OF
sand bed system.
The question at once arises, Is the mecbani-
cal filter system IS effective means OF puri.
hcation as the sand- bed blterf IL should be
stated in passing tbnt the So fold greater fl-
tration capacity possessed by mechanical
filters Is due tn the use Of small quantities OF
sulphate OF nlumina in connection with the
process. which well-known coagulant gathers
the. inorganic impurities and diseased germs
in shApa- to- ha filtered our and, slso,rby
forming n gelatinous film on the surface and
upper interstices Of the filter bed. thoroughly
prevents their passing through the bitsr. The
filters also arrest the precipitated coagulant.
and the most delicate chemical tests fail to
show q trncs OF IL in the Uttered water.
The city of Louisville has scided to, adopt
the mechanical filter process for the purifoa.
iton of it's water and 81 ia with reference to
what has been for months. and Is now going
on in Louisville. at great expense. 70 de.
mons'rate the efficiency Of mechanical filters
| TO successfully purify the water OF the Ohio
River, that ] address you this article.
| The Louisville Water Company last sum.
mer invited the various mechanical filter
companies Of the United States to q comnsti.
| tive test, which should extend over . sufflci
| entity long term 90 include all the different
| phases Of this river water In its hest and
worst conditions. Three companies resI or ded
| 10 the invitation, and the test began In Jolly.
\ 1876, and IL still in progress. The Louisville
! Water Company installed each filter company
| in separate house. lighted, warmed and
| supplied with upiltered water from the
| mains OF the company OF each competi'or. II
also supplied each filter cont papy with filtered
wntor with which their filters could bo
| washed. II wa- stipulated that the output of
each filter should not oe less than a quarter
| OF million gallons per diem, so that the condI.
| tions should approximate TO the actual work
OF unit litter ss part Of a LARGER plant.
Messrs. Long, the president. and Hermsny
the chief engineer OF the Louisville Company,
impressed with the far-react ing Importance
OF tiis test ~ effectinv not only tn ~ own
city. Int the whole question o: the pur,tica-
lion OF water supplies OF American cites.
installed largo and completely equipped
laboratory adjacent TO the filters. and plsced
IL In charge of Mr.. George W. Fuller. the
eminent bacteriologisf. recently biologist in
charge at the experimental station Mt Law
renee Of the Massachusetts State hotrl OF
health. and recognized authority on such
questions.
Mr.. Fuller selected a staff Of assistants and
entered laboriously upon his task, which was
no less than to take hourly samples OF The
filtered and unfltrred water. and to deter
mine bv analysis and bacterial culture the
reductions OF tho impurities in the water.
both chemical and bacterioloeicaI, effected by
the filters. IL is needless to say that this pro-
longed test, which will continue until August
thorougbness, either In Europe or America.
and that at it's conclusion the question of the
desirabiItty of mechanical filtration as a mode
of purification on any scale. however large,
Will Re settled one way or the other. IL NAV
also he said that while the rrecise results ard
the extent of the bacteriologic reductioY
effected by each litter will not be given to the
public at onoe. they are such as to give the
advocates OF mechanical filtration great en-.
couragement and to dem the capacity
of mechanical filters To absolutely purify the
Ohio water under its worst conditions II Ia
therefore. possible that bv or before the tima
when tho eminent engineers in charge OF
your proposed improvements reach the point
where they are roadv To construct the neces.
sary filters for the publication OF your wnter
supply, TINT they will 10 in n position 70
accurately know that mechanical filters will
meet your needs at saving OF many thou.