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18
The Bakehouses and Eating Houses in the district are frequently
inspected, and the desired standard of cleanliness in these
places well maintained.
SEWAGE WORKS AND TREATMENT.
The disposal of sewage is a matter of which certainty has not
yet reached finality; new processes and modifications of existing
ones are likely to occur.
The Royal Commission's Fifth Report (1908) for their general
conclusions laid down this maxim, viz.:— "It is practicable to
purify the sewage of towns to any degree required, either by land
treatment or by artificial filters, and there is no essential difference
between the two processes, for in each case, so far as it is not
mechanical, it is chiefly affected by micro organism. The two
main questions, therefore, to be considered in adopting a system of
sewage purification are, first, the degree of purification required in
the circumstances of each town and of the river or stream into
which its liquid refuse is to be discharged, and second, how the
degree of purification required can, in each particular, be most
economically obtained." Their report necessarily deals with
systems already in vogue, and they have, by personal and skilled
examination, tabulated exactly of what these systems are capable.
In the septic tank system they have clearly proved that it has
not solved the sludge difficulty; that practically only 38 per cent.
of the solids were digested.
That it did not destroy pathogenic organism, they found as a
result of a very large number of observations that the liquor issuing
from the septic tank is, bacteriologically, almost as impure as the
sewage entering the tanks.
On the third claim—which is much the most important—that
the sewage which passed through the septic tank was more easily
oxidized than sewage from which the solids had been allowed to
settle, either with or without the aid of chemicals in tanks which
were frequently cleared of sludge. The evidence received was
conflicting, and they say as it is a great importance in the purification
of sewage, they thought it most desirable to investigate
"most exactly."
Dorking was selected as a suitable domestic sewage (which is
almost identical with our own.)
Three identical percolating filters were constructed—one was
fed with settled sewage, one with sewage that had been subjected
to chemical precipitation, and one with septic tank liquor. The
experiment was carried out by the Commission's own resident
chemist, Mr. Eric Richards, and was carried on for over a year,