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the outfalls; 1,135 samples collected in the middle river (London Bridge to outfalls) and 162 samples
of the water of the upper tideway were subjected to extended examination in the laboratories; the
remaining 2,000 being entirely examined in situ.
Dumping of high explosives in River Thames.—Representatives of the department attended two
meetings of a conference called by the Board of Agriculture and Fisheries to consider the proposed
experiment of the Ministry of Munitions of dumping 50 tons of amatol or other tri nitrotoluene explosives
i nto the river, below the outfall and some miles from the open sea. The representatives of the Council and
the Port Authority urged objections against the disposing of such materials in shallow water, basing
their views on the results of investigations on the properties of the materials in question carried out by
the chemists of the two authorities. The valuable fertilising properties of one constituent of amatol
were also strongly urged as a reason against dumping without some previous treatment.
The chief engineer and the engineer of the Port Authority also made suggestions, which were
gladly received by representatives of the Ministry of Munitions, as to a less expensive means of conveying
the waste materials to deep water for disposal, and advocated this method. The proposal to dispose of
the materials in shallow water was abandoned.
Pollution of River Lee.—In consequence of an adverse report of the Lee Conservancy Board on
the effluent discharged from Enfield Sewage Works into the Lee Navigation, observation has been
maintained upon the water of the River Lee at its point of entry into the County of London Samples
of the water were obtained by the Council's chemist, whose report on the examination thereof substantiated
that made by the chemist of the Lee Conservancy Board. On the recommendation of the Main
Drainage Committee the Council, in July, decided to call the attention of the Minister of Health to the
pollution of the water of the River Lee below Tottenham Lock, resulting from the effluent discharged
from the Enfield Sewage Works, which entered the river through an intercepting drain. He was also
urged to take such steps as might be necessary to secure that the conditions producing this pollution
should be remedied at the earliest possible moment.
Bacteriological treatment of sewage.-— During the latter part of the year representatives of the
Public Health Department visited the cities of Manchester, Worcester and Sheffield, where the treatment
of sewage by the " activated sludge " process has been attempted on a working scale.
The subject dealt with is one of great importance both to the health and the amenities of London.
The river is one of the open spaces in London, the importance of which is greater perhaps than is generally
recognised, and this and other issues raised in connection with the treatment of London sewage should
be regarded as of the first importance to the welfare of the inhabitants of London.
Attention has been drawn to the desirability of investigating the relative advantages of aeration
by the following means:—
1. By diffusing tiles, as used at Manchester and Worcester.
2. By agitation and circulation, as at Sheffield.
3. By spraying the mixture of sewage and activated sludge through nozzles of the kind used,
for instance, in cooling condenser water.
In experimenting on these alternative methods of attaining the desired condition, of intimate
contact of air with the mixture of activated sludge and sewage, it is most necessary to work in such a
manner that strictly comparable results may be obtained. To do this the sewage supplied to the
respective experimental plants should be of the same quality, the same surface area should be
exposed to the normal superincumbent atmosphere, and there should be adequate means of measuring
the power supplied, the sewage treated and, in the case of the diffusers, the air blown through the liquid.
A natural corollary to these experiments would be a full investigation of the composition and
properties of the activated sludge obtained as soon as the amounts formed exceeded those needed for the
experiments themselves.
The third method of t eatment suggested is one that so far as I am aware has not hitherto been
attempted. It is suggested by a consideration of the conditions which are required for securing optimum
results, arrived at after a review of the many and different attempts at sewage treatment which have
been made. So far as can be judged from theoretical considerations it offers the best prospect, of any
method hitherto employed, of securing what are known to be the greatest desiderata in affecting the
most rapid oxidation of the putrescent matters in sewage. The admixture with the activated sludge is a
preliminary to any of the methods of subsequent treatment which it is suggested should for comparative
purposes be attempted. By spraying the sewage into the air and allowing it to fall in a fine state of
division into the tank which should be set aside for this purpose, the maximum aeration of the sewage
will be secured. At the time of this maximum aeration the sewage will have in it the agents, the humus
or activated sludge, capable of making use of these optimum conditions, and in this respect the treatment
will differ from any attempts hitherto made on other lines. In the end the relative merits of these
different methods of application will have to be judged by the question of cost in relation to the results
attained.