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of apparatus. At an early stage the experiments established the fact that London
sewage responded to treatment with activated sludge. Later experiments were
directed towards the treatment of the effluent discharged into the river from the
settling or sedimentation channels, and it has been found that effluent can be more
expeditiously dealt with than crude sewage. The tanks have been altered from time
to time and the quantities of liquid which can be dealt with have been largely
increased.
The existing experimental plant reached an ultimate capacity of about 150,000
gallons of sedimented effluent a day. At other places activated sludge plants were
working on quantities far beyond those dealt with in the Council's experimental
plant and the Council authorised the Main Drainage Committee to make a further
inspection of sewage works at provincial towns or districts. The Committee visited
the sewage works- of the Birmingham, Tame and Rea District Drainage Board and
those of the Corporations of Coventry and Reading.
The solids, known as sludge, which are obtained from the sewage after sedimentation
at the outfalls, are conveyed to, and deposited in, the Black Deep in the
Thames estuary. The Deep is also used by other authorities for the deposit of
waste materials and the cost of buoying the deposit area is apportioned among the
various authorities using it for that purpose. The Council's proportion for the year
1927 amounted to £264 0s. 11d.
The re-organisation of the Council's fleet of sludge vessels has been completed
and the fleet now consists of five vessels, namely, the Bazalgette (commissioned in 1887
and re-conditioned in 1921) of 1,000 tons capacity, and the Henry Ward (commissioned
in 1923), the J. 11. Hunter (commissioned in 1924), the G. W. Humphreys (commissioned
in 1925), and the John Perring (commissioned in 1926), each of about 1.500
tons capacity. During the year the Henry Ward became due for her first quadrennial
survey by Lloyd's, and the work entailed was carried out at a cost of £1,480. The
J. H. Hunter, the G. W. Humphreys and the John Perring underwent their annual
overhauls at a total cost of £2,450. The water supply for the boilers of the sludge
vessels consisted of hard water, and means were taken within the boilers themselves
by treatment with chemicals to prevent the formation of scale. This method is much
less satisfactory than separate treatment of the water in a softening plant. The
water softening plants at the two outfalls is therefore being connected with the supply
tanks for the sludge vessels, including the necessary pumps, at a cost estimated at
£850.
The pinnace Boqie, which is used by the superintendent of the sludge vessels,
has been overhauled and equipped with an internal combustion engine at a cost of
£456.
The repainting and decorating of the workmen's cottages at the outfall has
been undertaken, the Council having on 14th September, 1927, accepted the tender
of Messrs. George Eaglen and Son, Bow, E., amounting to £372 for the work.
Arrangements at an estimated cost of £160 have been made for the provision of
a separate cabin adjoining the flushers' mess room, in which they can dry and store
their working clothing.
The screening of the sludge produces a large amount of solid matter and a
contract was entered into with Mr. C. W. Parker, Bradwell-on-Sea, Essex, for the
removal of the refuse upon payment by the Council at the rate of 6s. a ton. The
estimated cost of this work is £1,560.
A footpath ran from Gallions Station, North Woolwich, through the property
of the Port of London Authority and the Gas Light and Coke Company to the Northern
outfall. Underneath the pathway the rising sewer main from North Woolwich
pumping station to the outfall had been constructed. The pathway has now been
closed to the general public, but is available for use by all authorised persons to and
from the outfall.
Deposit of
sludge at sea.
Sludge
vessels.
Northern
outfall.