Out of this number twenty-five were officials, viz. five lawyers, six
medical men, six chemists and eight engineers. Four officials were
further managers of artificial sewage purification works, but not one
single manager of natural purification works, i.e. a sewage farm
manager, was called, the term “sewage farm manager” being used here to
indicate an official whose sole duty it is to manage a sewage farm.
The entire absence of this latter class of official is so striking
that it cannot be due to accident, but must be the outcome of a
settled policy not to reopen questions conclusively settled by
previous inquiries.
Another point that strikes the observer is that the Commission only
called one zoologist and one botanist, as it is to these scientists
that belongs in the first instance the question of studying the fauna
and flora of sewage before the subject is taken up by other branches
of natural science.
Speaking on the whole, the evidence taken by the Commissioners forms
very interesting reading, and ought to be carefully studied by those
who have to deal with the subject. When now and again opinions are
expressed, which seem directly opposed to each other, it must be borne
in mind that here, as in other things human, unanimity of opinion,
though much desired, is apparently unobtainable.
To understand the conclusions fully, at which the Commissioners in
their Interim Report have arrived, it ought to be pointed out that
they had either to accept the recommendations in favour of land passed
by all previous Royal Commissions and authoritative inquiries, or they
had to show by incontestable evidence that their predecessors had made
grievous mistakes, and where!
Of these two courses, the present Commissioners have adopted, no doubt
for very good reasons of their own, the first, and they have started
therefore, in the conclusions to which they have come, at the point
where previous inquiries had left off, viz. that land treatment is a
very proper method of sewage purification.
But before referring more in particular to their observations on land
treatment, it will be necessary to point out that the Commissioners
evidently divide all methods of sewage purification into two main
classes, viz. natural and artificial methods. Into the former they
only place land treatment, whilst they call all other methods
artificial.
This division seems to have given a great deal of offence to all those
who have expressed decided and frequently very one-sided views in
favour of the “bacterial” treatment of sewage; but on closer
examination it cannot be denied that the Commissioners were quite
right in forming this view, as the following remarks will show.
For main divisions of all methods of sewage treatment two factors seem
to be of primary importance, viz. the agencies which bring about this
purification, and the way in which these agencies are employed. Now,
it will not be denied that all agencies are natural ones, whether the
process employed is a purely chemical one, a purely “bacterial” one,
land treatment pure and simple, or a combination of these, and, at the
present time no such thing as an artificial agency is known; indeed,
it is perhaps not too much to say that there cannot be such a thing
as an artificial agency. Hence it is impossible to divide sewage
purification methods in this respect by the agencies employed, and one
is bound to fall back upon the way in which these agencies are
employed. Here it is no longer open to argument whether a chemical
process or the contact bed system—oxidation bed system—is artificial,
or whether the land treatment is natural! For who would deny that
masonry or concrete tanks and the materials contained in the same are
artificial products—i.e. products formed by man—and that land is a
natural product—i.e. formed by nature—and that further the soil is the
natural home of bacteria. Hence it must be perfectly clear, even to a
casual observer, that the line of demarcation drawn by the
Commissioners between all known systems of sewage purification is a
correct and legitimate one, and that all objections to such a division
are based on misconceptions.
Concerning land treatment, the Commissioners observe, “We doubt if any
land is entirely useless,” but further on they observe that peat and
stiff clay lands are generally unsuitable for the purification of
sewage. Concerning peat, nobody acquainted with the subject would
probably differ from their conclusions owing to the great amount of
moisture contained in this material; but as to clay soils, the
Commissioners when making this statement must have known that there
are several successful sewage farms on this kind of land in existence,
such as the sewage farms at South Norwood, Wimbledon, Warwick and
Leicester, not to mention others. In the case of Leicester, although
the land is a very dense boulder clay, the Corporation of this town
have just purchased the freehold of the farm for about 160,000_l._
Dealing with the artificial processes from a chemical point of view,
the Commissioners are of opinion that it is practicable to produce by
these processes alone, either from sewage or from certain mixtures of
sewage and trade refuse, effluents which might be discharged without
fear of creating a nuisance, and that in consequence the Local
Government Board would be justified in modifying, under proper
safeguards, the present rule as regards the application of sewage to
land.
The artificial processes referred to in the observations appear to be
the following:—
Closed septic tanks and contact beds.
Open septic tanks and contact beds.
Chemical treatment, subsidence[6] tanks and contact beds.
Subsidence tanks and contact beds.
Contact beds alone.
Closed septic tank followed by continuous filtration.
Open septic tank followed by continuous filtration.
Chemical treatment, subsidence tanks, and continuous filtration.
Subsidence tanks followed by continuous filtration.
Continuous filtration alone.
The Commissioners do not say what these safeguards are, in fact they
state that no general rules concerning them can be laid down, and that
in the case of these artificial processes it is necessary to consider
every case on its own merits.
The next point dealt with is the bacteriological quality of effluents,
and here the Commissioners observe: “We find that, while in the case
of effluents from land of a kind suitable for the purification of
sewage there are fewer micro-organisms than in the effluents from most
artificial processes, yet both classes of effluents usually contain
large numbers of organisms, many of which appear to be of intestinal
derivation, and some of which are of a kind liable under certain
circumstances at least to give rise to disease.”
No particulars of effluents from sewage farms are given, and later on
it will be shown that this conclusion of the Commissioners is not in
accord with the results published up to now and available concerning
the bacterial purity of effluents from land treatment.
The report concludes with some remarks on rivers pollution. The
Commissioners state that it is of the utmost importance to provide the
simplest possible means for adequately protecting all rivers, and they
think that this subject is of such grave importance “as to demand the
creation of a separate Commission or a new department of the Local
Government Board, which shall be a supreme Rivers Authority, dealing
with matters relating to rivers and their purification, and which,
when appeal is made to them, shall have power to take action in cases
where the local authorities have failed to do so.”
Summing up the observations on the practice of sewage treatment, it
may be said that as a result of their extended inquiries, the present
Royal Commissioners have at the end of the century re-established land
in its position as the first and only natural method of sewage
purification, beside which they have recognised artificial
(biological) treatments as being under proper safeguards admissible
for the purification of sewage.
Before concluding this portion of the observations, it is necessary to
mention the valuable work done by Mr. Scott-Moncrieff and Mr. Cameron,
who, contemporaneous with Mr. Dibdin, but quite independently, had
experimented with sewage and evolved their own artificial methods of
sewage treatment.
These remarks must suffice for the more historic portion of the
subject, viz. the progress of sewage purification during the last
century, and it is time now to direct attention first to natural and
afterwards to artificial sewage treatments.
[4] Two of these have since retired.
[5] This report has just been issued (August 18, 1902), and
although the special reports it contains are of the greatest
interest, it is not necessary to refer to it again in these
observations.
[6] The expression “subsidence tanks” is intended to denote
tanks which are used in such way that little or no septic
action is produced.