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Air—Safety tests (Northern Outfall) 5,940
Air—tunnels 255
Building materials 872
Chemical, drugs and medical supplies 63
Clays, sub.soils and borehole waters 2,580
Detergents and soaps 170
Fertilisers and feeding stuffs 83
Floor oils 83
Foods 596
Gases from sludge digestion plant 371
Instrument sets (ambulance) for sterilisation 114
Lamps, gas detector 605
Laundry tests 102
Liquor (effluent from Beckton Gas Works) 721
Meals 56
Miscellaneous 570
Oils, lubricating and fuel, etc 48
Paints, varnishes and distempers 1,905
Petroleum and allied samples 58
Rain water (atmospheric pollution deposit gauges) 80
Rubber and rubber substitutes 144
Sewage and effluent 2,800
Sludge, primary and digested 1,996
Sludge, activated 1,946
Smoke in air, determinations 4,153
Sulphur gases in air, determinations:
Lead peroxide cylinder method 129
Volumetric method 4,255
Trade effluents 2,178
Water, etc., from steam raising plants 1,054
Water, chemical and bacteriological examinations:
Drinking water 841
Swimming baths 2,112
River water 2,955
Water, miscellaneous 59
Research and investigation samples at Northern and Southern Outfall
Works 2,196
42,090
Sewage treatment
The scientific work on this subject is carried out in close collaboration with the staff of
the Chief Engineer. Officers of the two departments work side by side at both outfall works
and have daily consultations and exchanges of information; the Scientific Adviser and the
Divisional Engineer in charge of main drainage hold weekly meetings, at which analytical
results and research progress are discussed and policy of operation and ways and means
of improving efficiency are considered.
Early in the year the modernising of laboratories and offices at the Northern Outfall
Works was completed and up-to-date and time-saving equipment installed. This greatly
improved the facilities for investigating, on both laboratory and pilot plant scale, problems
associated with the operation of new and greatly enlarged treatment works.
A brief survey of the work carried out at the laboratories at both outfall works follows:
NORTHERN OUTFALL WORKS LABORATORY—
Primary sedimentation—This is effected mainly in the new tanks installed in 1955. An
exceptionally rainy summer caused a marked increase in the average daily flow to the
works, and it was necessary to settle about one.sixth of the total flow in the old sedimentation
channels. The sewage admitted to these channels is considerably stronger than that
entering the new sedimentation tanks because of the position of the incoming sewers.
Although the detention period in the old channels is sufficient to permit of a high percentage
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