Los Angeles daily herald., 1890-01-02

,ass, hsrm nal of the two, might be turne6 into
J s., ali stre am of quiet water with cempara-
piUelv little danger OF causing nuisance For
this purpose the sewage 10 turneo lIso % coaior ar
similar substances. by this metnoo srvas
deal of the suspended matter is kept BACK py tne
filter, but enough OF it escapes 70 cause auiansSa
fyom nollution or nuisances II the n!ter Is
coarse enough to serve for sny length OF ime.
In case it consists Of material nne enough 70
retsin all of he suspended after, II soon CLOGS
M and becomes a nuisance ITSELF II seoi zen
tation is resorted to, the sewage Is allowed 10
siow slow v through a series OF tanks, wnere,
by reason of the velocity, 1t is largely 9epriveo
OF its solid contents, the same accumuiaSns aa a.
from time to time. ne effiuent Is rarely, II
ever, much better fitted than Ordinary cruue
sewage to be washed into small stream OF
still water Both these methods have rarely, II
ever. proved satisfactory, and tney are lonkeo
unon AS Insufficient and undesirable means 10
purify and dispose OF sewage
S-cHEMIcAL PRECIPITATION.
Another method often applied for the dispo-
sal f sewage. before 1t is finally discharged on
land or into large bodies of water, is the use OF
cheap chemicals, which precipitate the solids
kept in suspension, and some OF the offensive
matt II which is in solution. A higher degree
| of purity is obtained thereby than by any OF
| the former methods. We find this method ap-
piled in about fifty cities in England. The
suspended and some of the dissolved impurt-
must be held comparatively at Test in large
tanks, by the admixIure of milk OF lime, SUI
phate of slumina, or other salts. To clarity or
dinary city sewage requires about one ton OF
quick lime, slaked and ground fine, for each
million gallons OF sewage. The preclpltate,
consisting of . greyish mud, will amount to
about one ton for each fifty Thousand gallons
OF sewage. 1t contains over ninety per cent OF
water.
when near large river or the sea. this pre-.
| cipitate commonly called sludge, is pumped
/ ~ kfan,s TO-, ~ 1a
points, or it is dried and lpaded into the soil.
In still other cases it is passed through filter
presses and reduced to cakes, which can be
tate, OF sludge, is almost vaiueless, even in
England. The smount of putrescible matter,
held in solution, alter the suspended matter
has been removed, is still considerable, and
the efiuent becomes foul in a short time. un-
less diluted with large quantities of water, or
filtered slowly through land.
The cost of precipitation is considerable. 1t
head per annum. 1t was esiimat ed at SO cents
Of Boston: and e5 cents for Milwaukee, Wis.
4.-LAND DISPOSAL.
It is universally accepted by sanitarians and
engineers that the most efficient and most de-
rigation on suitable lands. The propertie, OF
the soil as powerful deodorizer have long
been recognized. Its capacity as filter ex-
ceeds that of an artificial one, chiefly because
the irrigation fields represent vastly greater
area
Recent scientific researches and experiments
have vastly contributed to the under stan ding
OF the properties Of the soil as destroyer Of
hfeless organic matter, and sewage irrigation
will in the future ce carried on with more sci
entific precision than heretofore. Although ii
can now be relied upon as q safe and efficient
method for sewage disposal, it will be more and
more appreciated by the public at large, as sci
ence Can explain the wonderful workings OF
| invisible organisms in the soil upon organic
Inns for hrO N wit ., ba faa
are that sewage can be made chemically pure
only by land filtration. and that this should al
ways be resorted to for the disposition of sew
| age whenever practicable.
| The soil upon which the sewage is to be
spread, or through which it is TO be filtered,
should be light, sands or gravelly. Heavy soils
are -ess suitable, and they msy be OF such ma
| ture that they are absolutely WORTHLESS for sew
age disposal. In all instances the subs oil
waters must not be closer to the surface than
six or seven feet in order to Iertect publication
and the water must therefore have q chance tC
drain off. Where the underground water natu
rally stands higher, the land must be artif
| cislly sub-drained. This must be done also II
the ground is lot porous enough to admit the
| sewage to seep through readily.
There are two methods in vogue for the dis
posal of sewage by irrigation; one has in view
| the use of land for cultivation, the other ha'
only the publication OF sewage for its object.
The former method requires far more lant
than the latter. Where sewage irrigation il
carried on to raise crops the water is eithe
| BpIGGQ
| burrows till it soaks away.
| Where publication is the only object, tn,
| sewage is crowded upon subdraiued lands in
termittently. time being given to each field be
| thoroughly AIRED. In all cases where irrigs
| ton is carried on successfully, the land has t.
be specially prepared for the reception of tn
sewage waters.
in many cities, mainly in Europe. Berlin ant
PARIS have ths largest tracts devoted to thi
purpose.
In Berlin the sewage of about one million pei
SONS is delivered upon ia ms consisting OF owe
IL 900 acres OF sandy soil, ditched and partl.
sub drained. The water is applied both il
summer and In winter, during rains and wheI
dry. Crops of various kinds are raised, but tht
income from sales does not equal the expendi
lures.
| In Paris the sewage of about one-ffth of th,
population, or of about 900 persons, /
conducted upon about 1000 acres o. sand.
soil, some of which is under-drained, but thu
| sewage is used only wnen he farmers desire it
AT other times it runs into the river, A variety
| of products are raised, and the value of thu
wafer is considerable, having increased tn,
| rent OF the land tenfold
| Pullman, ILL.,, has the largest sewer farm il
our own country, next to the one south OF Lo
| Angeles. 1t receives the sewage OF over 500
persons, and contains about 100 acres of lanC
prepared and underdrained. The most pro
ductive crops are garden yegetables. Durinl
the period when the application of sewage
might tnjure the crops i5 is turned into Lake
| Calumet. Under these conditions the profit O
the farm is about fifty dollars per acre per an
mum.
In Los Angeles the sewage of about IL 90,
persons is applied to about !, 700 acres. 1t i
not used during wet weather. The crops ar,
abundant and profitable.
Il Where the land is not sufficiently por GUS t
allow of the filtration of such large quantitie
i OF water the sewage is used simply for surface
irrigation, where the publication Is largely oh
tanned by aration ana oxidation on the surfac
OF the land before 1t sinks, and com parativel
greater portion is absorbed by vegetation
From the experience gained with sewag
irrigation works, it is found that the eff1ueu
| water may, with care, be made quite satisfa
tory. 1t is also found that SUCH works ar
profitable only If the sewage is applied whe
the crops can I've benefited.
II On toe sewage farm at Reading, England
land is rented at fifty dollars per acie If sewag
Can be used only when needed, and in sue
amounts as may be desired. 1t cannot be rente
at any price when it is necessary to take tn
: sewage at all times. Ordinary land withou
7 sewage rents at ten to fifteen dollars per acre.
Sewage farms need not cause any nuisance
Some smell may be noticeable at the ditche
toward evening when the air is damp, and OF
D muggy days. IT may particularly be the cas-,
when the sewage is not delivered fresh.
. There is no we'll authenticated case wher
sewage farms have caused sickness. In Eng
land DAODp rasida lands ad hon