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47
suspended matters beyond a certain size. A brush revolving in an
opposite direction cleans the net as it passes, and the solid matters
are cleared to one side and removed by manual labour. The
sewage then passes through a well, inside the liming house, and
from thence through two valves into one or the other of two small
detritus tanks covered with corrugated iron. These tanks have a
total capacity of 24,000 gallons. At the centre of the length of
these tanks, scum boards are fixed, the bottom edges of which
are at a distance of 24-ins. below the level, the upper edges
being above the water level; the outlet end of the tanks have also
scum boards projecting to a distance of 12-ins. below the water
level, and the top edges of same, of course, being above the water
level.
The Sewage passes under these boards and over a lip in a
continuous stream into a carrier.
Four Precipitation Tanks of 600,000 gallons capacity are in
use, with the necessary apparatus in connection therewith. The
tanks are arranged so that they may be used on the intermittent
or continuous principle.
The effluent from the Precipitation Tanks passes from the
tanks into about f acres of first Contact Beds. The feature of the
Works is the ample provision made for the effectual aeration
of the whole system.
The lower outfall takes the Sewage from one Institution only,
viz., Hanwell Asylum, and discharges into two covered tanks, the
combined capacity of which is about 57,000 gallons. The Sewage
from these tanks is pumped up through a rising main and discharges
into a well at the liming house before mentioned, and then passes
through the same process as the District Sewage. The precipitated
sludge passes into a sludge well near the low level tanks, and
is pressed into cake form by means of a filter press.
The effluent is tested every day, with a view to ascertaining
the efficiency of the process. The phenomenal growth of the
district even now requires extension of works, and the Surveyor
has the matter in hand.
The whole of the machinery at the works is driven by gas
engines, the gas being at present supplied from a Dowson gas
generating plant, but arrangements are now being made for the
laying on of town gas. It is also hoped that water will be laid on
to the farm at no very distant dale.
Much good has been done during the winter in further levelling
the land at the Farm so as to improve distributing facilities for
the Sewage.