The record-union., 1899-10-21
What Engineer and Expert Herring
Says of Our Facilities.
Fa1OrS Natural Filtration, and Says the Question
of Permanency Can be Tested for
Few Thousand Dollars.

! months without washing. Slow
! filters, he said, sometimes had to be
| cleaned out once a week, the process
F., generally employed being to scrape off
about two inches of the sand and then
! fill in the tank after the sand had been
cut down to- a thickness of two feet.
| Mechanical filters. he said, would
necessarily have to be cleaned oftener
i-once and sometimes twice a day.
| Many cities had employed the rotary
/ cylinder process to precipitate the sus-
pended matter in the water after the
alum or other coagulent had been
| added.
Mr. Herring said the relative value
! of slow and mechanical or rapid filters
| differed little as to efficiency, and in
making a selection the item of cost
) would be the principle thing TO con-
slider. In either case intelligent super
vision would be needed-indeed, it was
! indispensable. A fast filter would ne
cessitate employing a mechanical engi-
neer, and while that parsonage might
! be dispensed with in case a slow filter
were adopted, there would still be need
| for a careful competent man to take
| charge, and in either case a chemist
should be employed. He explained that
if the coagulated covering of the rapid
| filter should break, the result would be
/ impure water for the city.
! Mr.. Herring explained that the essen
| tial point in a mechanical filter used
! for removing bacteria was film which
/ formed on the top of the sand, caused
! by the addition to the water of certain
coagulating chemicals, forming a kind
I
from going through He also explained
that after washing the mechanical filter
| the water should be allowed to run to
waste half hour until the film form
ed In a slow filter the water would
have to run to waste twenty-four hours
before the film would form.
The slow filters Mr.. Herring explain
ed, We're those through which ten cubic
feet of water would pass per square
foot of filter in a day, and the rapid
or mechanical filter would pass 300 Gu
bic feet of water through the same
filter space in the same time. For that
reason, if anything got wrong with the
mechanical filter it would be a more
serious matter than with the slow filter
The engineer said that the bacteria
which passes through the filters are
He did not know whether or not there
had been any definite decision about the
matter, but he believed the idea pre-
vailed among scientists that the slow
filter was the better.
Mr.. Herring could not, of his own
knowledge, state whether the quantity
Of alum necessary for filtration would
be deleterious to health. though medi-
al E,o =
that it would have a bad effect upon
delicate organizations if taken contin-
uously. From one to four grains of
alum was used per gallon, and portion
of that would be precipitated and left
in the filter. Indeed, it was stated
that by careful watching all of the
alum might be precipitated and left in
the filter. He had never known of
complaints. from a health standpoint,
from the use of alum for coagulation
purposes. He thought that with proper
care no evil would result from the use
Of alum He had never hesitated to
recommend it's use.
Mr. Herring thought there would be
no difficulty in fltering the water be-
cause of the fineness of the silt, mas
much as it was. he understood. COM
said. that in some instances the fine silt
would not be deposited in settling ba-
sins, but the addition Of alum had rem
edied the matter. He thought there
would be no serious difficulty in separ-
ating the silt from the water here If
responsible men were put in charge.
he thought, the water would come out
clear.
r6 70
the odor noticeable when the water
runs down from the tules. he had never
known of an instance where filtration
had not removed such odor. He recall
ed a number of instances where odors
arising from vegetable matter had been
entirely removed.
In answer to question by DR.. Hen
derson, as to whether the water in
wells east of this city might become
contaminated from surface or sipage
water Mr.. Herring was positive that
it could not Water. he explained. is
very soon purified after it comes in
contact with the soil. In most instances
it is purified in passing through the
twelve inches next the surface Rain
water, he explained contains much bac-
terra and vegetable matter, and on one
occasion rain fell in London which was
nearly as impure as the sewage of the
city
On the surface Of the soil. Mr.. Her
ring explained. bacteria begin to work
and separate from the water as 1t goes
down The oxygen in the ground had,
he thought. much to do with the puri-
fication, inasmuch as after passing be-
low the surface four or five feet the
publication ceased to a great extent.
The water from manure and sewage,
when used as a fertilizer, was fire.
quently wholly purified by passing
through four or five feet of soil Water
in eesspools, ETC., would not become
purified by sipage through the bottom
of the receptacle, though there might
De an Improvement.
In answer TO a question as to whether