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33
appointed to be a member of this Committee. He also continued to be a member of
the "Thames Survey Committee," which operates under the auspices of the Department
of Scientific and Industrial Research. Close liaison was maintained with
research work proceeding in this country and elsewhere, particularly in the United
States of America, on the treatment of sewage and on river sanitation.
The laboratories at the two outfall works carried out the chemical analyses
necessary for the control of the various plants during the year. Research work was
also done on several aspects of the sewage treatment problem and particularly in
reference to (a) the dewatering of sludge by a new process involving freezing after
the addition of chemicals ; (b) preaeration of sewage for grease separation ; (c) modifications
of operation of the present activated sludge plant; (d) cleaning of diffuser
tiles. Item (a) resulted in a paper on "Sludge dewatering by freezing with added
chemicals" which was presented to the Public Works Congress in November by three
officers of the Chemical Branch.
The question of trade discharges into sewers was investigated in a number of cases
as to compliance with the appropriate sections of the Public Health (London) Act,
1936, and advice was given in many instances on whether a proposed discharge would
be within the terms of the Act, sometimes with suggestions as to possible pre-treatment
which would render it so.
Safety lamps used in sewers were tested and adjusted periodically and an officer
of the Chemical Branch gave advice and assistance in training men employed on
sewerage work in the use of oxygen breathing apparatus under emergency conditions.
The sewage treatment service is a joint function of the Chief Engineer's and Public
Health departments and special mention should be made of the cordial relations which
have so greatly helped in maintaining the efficiency of the operations. Weekly
conferences of the Divisional Engineer (Main Drainage) and the Chemist-in-Chief and
their senior officers have been of the utmost value in this respect.
Regular chemical analyses and bacteriological examinations were made of the
drinking waters derived from private wells at various Council premises and also at a
number of hospitals, this service having been continued at the request of the various
hospital committees. All these water supplies are chlorinated before use and the
dosage was periodically checked.
Public
health
The air in the Council's vehicular tunnels under the river Thames was regularly
examined in order to ensure that the carbon monoxide content did not exceed the
safety limit; in view of the continued use of petrol containing lead compounds, the
lead content of the air was also checked occasionally and was found to be safe.
Considerable work was done during the year on atmospheric pollution, assays
being made by various methods of the polluting matter (total deposit, tarry matter,
sulphur gases, smoke, etc.) in the air in various places within the county and also, for
comparison, at two observation stations outside it. This work was done in conjunction
with a scheme sponsored by the Department of Scientific and Industrial Research.
In compliance with a Committee Order, a special survey was made in conjunction
with the Public Control Department of the emission of industrial chimney grit in the
vicinity of all the electricity generating stations in the county. In some instances
the quantities were judged to be unduly high and the appropriate sanitary authorities
(borough councils) were notified.
In accordance with an official arrangement, the Chemist-in-Chief accompanied
the Chief Alkali Inspector, Ministry of Health, on his periodical visits to Battersea
Power Station to test the efficiency of the flue gas-washing process for the removal of
sulphur compounds. At the close of the year only 70 per cent, of the flue gases were
being washed at this station and no part of the gas-washing plant at Fulham Power
Station has yet been reconditioned and put into operation.