Daily Kennebec journal., 1902-04-15
Filtration Of DRINKING Water.

In recent article, William G. Toplis
cd WIZ the zone lnterestirrs facts connect
et w. the Hitration of water on large
scale, from which the following is taken:
it mas long been known that impure
Wdter percoiated through a deep bed OF
sana sam issues greatly improved in chemical
ct+traC t put the precise nature OF th9
changes We're not thoroughly understood
unql koch made possible the isola tion
,nd teria s'luf sde OF Individual species Of bac
iena - ~, seeks TO copy the changes 50
lohs carried out in springs, but with the
precise care of scientific exactness. tn
sahd inter- therefore, means the most eX-
actlhs painStaking care to establish the
proper conditions, together with the wise
apPd.cd'dot ia5itai a Oh much chemical, Dacteilo-
loSlcal, ana engineering knowledge.
ne sdnu Is not the filter. the sand Is
Simply me bones upon which the hitter
grows. Surrounding each individual bao-
terium, under the microscope may be
seen a gelatlnous envelope, when MAN.
bacteria are Joined together in mass; this
envelope may be seen collectively With
out q lens, forming jelly-like mass and
IS then called a Zoogloea. In sand hi
ter this Zoogloea attaches to and covers
completely each grain of sand in the fl
ter Ihe, grains form fine avenues
through which the water is compelled tc
pass. Inc bacteria line these az
@ @enues. me me, water carrying its organic
contents DflngS 1t as a food for the BAG
terra in the Zoogloea. AS the water
! passes along, 1t is gradually relieved o.
It's organic matter, because it is dlgeSted
! by the bacteria. and in its place bears
away the products of the decomposition.
Sublime in its beautiful simplicity! We
| have chemical and biological proof Of
| each change
| 'WinoSradsky has shown that nitrify-
! ing or oXidizing bacteria grow upon
| media altogether Inorganic. No less thdn
three separate and distinct classes OF or
ganisms are concerned in the transition
of nitrogenous organic matter g the i'll
| c FOL
| down INTO ammonia-as the first change
| by one class of organisms. and here be
comes trHiy lnorganic The second step
| is enc of oxidation, and the ammonia
becomes nitrous acid through the agency
| Of another entirely separate organism
quite different from the first. In the thlrd
and final step, the oxidation is completed
by another organism entirely distinct
| acid becomes nitric acid, which unites
| with any base at hand, and is delivered
| as such in the efiluent. This is why our
filter working under favorable condition;
| shows neither free nor albuminOid am
| monia, but does return the equivalent in
| nitr3tes that an ammonia determination
| on the raw water would call for As be
| fore stated, the proper conditions must
| be preserved, and one of these is the e.-
| ement of time; how rapidly may we
| pass the water through the sand as an
economical proposition? AS might be pre-
| dicted the character of these changes
! NpuiC ItitilTe IL SLOW rate Ol NOW, l!ltlt-
| fore, filtration must be restrained or con-
| troled and maintained at uniform rate
| notwithstanding constantly diminishing
ffltering capacity due to the clogSing
| This is accomplished in several ways by
| automatic devices. 1t is not safe to carry
the filtering rate much beyond three mil
| lion gallons per acre twentyfour hours
| This has been found by actual working
| conditions to be the safe limit so far a.
| meteorological and chemical conditions
are concerned. "A three million gallon
rate is equivalent to filtering ten vertica
feet of water over the entire area of fiji
| ter in twenty-four hours. The problem;
| met with in water purification seem tt
| change with each source of supply, anl
| so variable are they that no municipality
| would undertake the erection of a fitra-
| ton plant without exhaustive study OF
| the condition covering practically a whole
| year"