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56
was given as to measures which should be taken to improve the quality of the water.
At one of these wells (Hollesley Bay labour colony) a chlorinating plant was installed,
and at Mitcham children's home the well sump and tanks were twice treated with a
strong dose of bleaching powder.
Greenwich
power
station.
In addition to the sampling and examination of fuels for the tramways and other
departments and the routine necessary for the maintenance of adequate control
in the water system of the power station and in the combustion of the various fuels
employed, the work of the Greenwich laboratory during the year has included the
investigation of a number of problems connected with coal economy and corrosion.
Outfalls.
The regular examination of the sewage treated at the outfalls and of the effluent
and sludge produced has been carried on since the present treatment was begun
in 1888 and 1890 respectively. At the southern outfall the percentage of dry matter
in the sludge was slightly below 6 per cent., the corresponding figure for the northern
outfall being 8-1 per cent.
River
Thames.
ihe dry matter in individual cargoes varied from 4 to 14 per cent, at the southern
outfall, the mode lying between 8 and 9 per cent. The corresponding figures for the
northern outfall varied between 3 and 16 per cent., the mode lying between 7 and 8
per cent., with a decided skew distribution in favour of drier sludges.
The examination of the water of the Thames near the outfalls, begun in 1885,
and more extended examinations in the course of the sludge ships and at a few places
above the outfalls have been continued. The condition of the upper reaches of the
tideway have been investigated. The weather conditions during the summer were
such as to obviate the necessity for treatment of the effluent from the Council's
outfall works.
Sludge
digestion.
Experiments are being conducted at Crossness on the anaerobic digestion of
sludge. The plant is designed to allow of agitation and of digestion at varying
temperatures. The gas evolved can be measured and its calorific value determined.
This work has not progressed sufficiently for any useful discussion of the results
obtained.
Biochemical
purification
plant at
northern
outfall.
The large plant designed to treat some five million gallons per day has been
brought into partial use. Towards the end of July the re-aeration tanks were filled
with crude sedimented effluent and air blowing started. Actual treatment was begun
on 25th November. At the end of the year about two million gallons of this effluent
were being successfully purified by the action of the humus (" activated sludge ")
which had then been formed. This amount has since been increased, and it is
anticipated that as the amount of humus available for treatment is increased, a much
larger volume of crude effluent can be purified to the desired degree.
The working of the plant, which is of entirely novel design, has so far presented
no special difficulty, although naturally it has required constant skilled supervision.
A point that will be of interest is the provision of settling tanks of two different
types, enabling a comparison to be made between the results respectively obtained
in them.
British
engineering
standards and
other
committees.
The chemist has served as a nominee of the Council on three committees of the
British Standards Association; one on the Sampling and Analysis of Coal, which
has during the year extended its activities to include coke; one on Standard
Definitions and Tests for Fire Resistance and the combustibility ; and more recently
one on Containers for Acids and Corrosive Liquids. The two first-named committees
have issued tentative reports which have been circulated for comments to organisations
concerned in the matters dealt with. The chemist is chairman of two panels
of these committees. He is also a member of the Government Committee on
Atmospheric Pollution.
Vehicular
tunnels.
The regular examination of the air in the vehicular tunnels at Blackwall and
Rotherhithe was continued throughout the year, attention being concentrated
on the period about 10 a.m. when the worst atmospheric conditions have been
proved to occur. The new blowing fans in No. 2 shaft at Blackwall came into operation
at the end of July, thus completing the new ventilation scheme at this tunnel.
The 104 samples examined there during the year gave an average carbon monoxide