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124
Sewage
treatment.
The experiments in connection with the biological treatment of sewage on the
activated sludge basis have continued during the year with the new tanks which
have been equipped with different types of appliances for agitating the sewage.
Three processes are now in operation, namely (i.) the diffusion of air through the
sewage by means of porous tiles fitted in the bottom of the tank; (ii.) the agitation
of the sewage by paddle wheels which constantly expose fresh layers of the sewage
to the air; and (iii.) the spraying of the sewage into the air through a nozzle.
Experiments are being continued but it would be premature to attempt at present
to make a final decision on the merits of the three methods.
Owing to the condition of the Thames during the summer, due principally
to the small flow of water over Teddington weir, the use of chemicals for precipitating
solids at the main drainage outfalls was resumed. Treatment had lasted for less
than two months when the condition of the river improved, and it was possible to
discontinue the use of chemicals. The cost, including expenditure on preliminary
work, chemicals and labour, amounted to approximately £2,(XX).
Northern
outfall.
The Council on 19th December, 1922, approved expenditure of £14,000 in
respect of the installation of two new boilers of the water tube pattern at the
Northern outfall in place of the boilers in the eastern boiler house which were worn
out after more than 33 years' service. During 1923 tenders were accepted for the
boilers and accessory plant as follows:—Stirling Boiler Company, Limited, for
boilers, £8,834 ; John Mowlem and Company, Limited, for foundations, etc., £2,298 :
Wilson and Perrett, Limited, for water softening and oil extracting plant, £794 5s.;
Dilworth and Carr, Limited, for piping, £1,156 ; Leeds Engineering and Hydraulic
Company, Limited, for hydraulic ash-hoist, £254. A soft water tank of re-inforced
concrete was constructed by the Council's jobbing works contractors (John Mowlem
and Company, Limited), the price tendered being £543. The overhead sludge
tanks were found to need considerable repair, and the Council on 14th February,
1923, accepted the tender, amounting to £3,434 of Messrs. Flavell and Churchill
for the work. Further repairs to the pier, which have proceeded continuously
since 1913, have been carried out during the year at a cost of about £1,000. This
work was executed by direct employment of labour as was also the work of repairing
the railways at the outfall, at an estimated cost of £450.
Repairs to the river banks were carried out by the jobbing works contractors
at a cost of about £2,500. Repairs to the pipes and valves controlling the supply
of water from the river to the ponds and condensers were authorised at a cost not
exceeding £1,800.
Southern
outfall.
After the opening in 1916 of the new engine house at the southern outfall, it
became possible to lay off for overhaul the main beam-engines and pumps. The
work is proceeding continuously. The expenditure authorised during 1923 amounted
to £1,500 for work to be executed by direct employment of labour, and for the purchase
of valves and other parts from Clayton, Goodfellow and Company, Limited,
at a cost of £486 10s.
Sludge
vessels.
The roads and paving at the outfall have been repaired at a cost of £430 1s. 8d.,
and a new sludge loading pump has been installed at a cost of £263 12s. 4d.
The fleet of vessels for conveying sludge from the outfalls to the Black Deep
was built up between 1887 and 1895 when six vessels were obtained, each of a carrying
capacity of about 1,000 tons. These arrangements were not altered until the
present year. The new sludge vessel, the s.s. Henry Ward, built by William
Beardmore and Company, Limited, was completed at a cost of £42,914, and placed
in commission on 28th September, 1923. She has a carrying capacity of 1,500 tons
and is manned by a crew of the same size as the older and smaller vessels.
The question of dealing with the older vessels has received careful consideration.
The s.s. Bazalgette was re-conditioned during the year 1921 at a cost of £55,207, and
such re-conditioning may give her a further life of 15 years. Extensive repairs were
carried out to the hull of the s.s. Barking and it was intended to complete her