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168
To ensure that the requirements of the several Orders in force from time to
time are being observed, and that the animals are not caused unnecessary suffering
during transit and are free from signs of disease, the Council's inspectors pay numerous
visits to railway wharves, depots, etc., where animals in transit are collected. The
visits during 1926 numbered 2,852, the animals examined being—horses 1,955,
cattle 49,343, sheep 80,697, swine 18,897, making a total of 150,892. There were
30 infringements, 26 written cautions, 4 cases of legal proceedings and 3 convictions
with penalties and costs amounting to £11 4s.
Enforcement
of orders.
CHAPTER IV.
MAIN DRAINAGE.
The district drained by the London main drainage system has an area of nearly
149 square miles with an estimated population of 5,480,000. This includes an area
of nearly 32 square miles, with a population of 868,000 outside London. When the
districts of Leyton and Walthamstow are incorporated in the area served by the
system in accordance with the provisions of the London County Council (General
Powers) Act, 1925, 11 square miles, containing a population of over 250,000, will
be added.
Drainage
area and
statistics.
The quantities of sewage, etc., dealt with during 1926 were as follows :—
Sewage treated—- Million gallons.
Northern outfall 59,857.9
„ ,, (daily average) 164.0
Southern outfall 35,163.9
„ „ (daily average) 96.3
Sludge sent to sea— Tons.
Northern outfall 1,650,000
„ „ (daily average) 4,521
Southern outfall 804,400
„ „ (daily average) 2,204
The sludge vessels made 1,724 trips and travelled altogether 190,380 nautical
miles.
For some years past experiments have been undertaken in connection with
the biological treatment of sewage on the activated sludge basis, using various types
of apparatus. The methods experimented with have comprised (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; (iii.) spraying; and (iv.) the stirring of the sewage
by means of vertical stirrers. The last-mentioned method was installed during the
year. 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.
Sewage
treatment.
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
1926 amounted to £308 5s. 8d.
Deposit of
sludge at sea.