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4.
Fitting the set-up kit
4.10 Fitting sludge return in final sedimentation tank
The sludge is returned to the preliminary sedimentation using
air lift pumps. The air lift pumps have several intake pipes to
ensure that the sludge is extracted evenly over the tank
base.
The lift pumps are supplied in two parts made of HT pipes.
The two parts are connected with the sleeve and pointed
end.
For final sedimentation tanks with a dividing wall, a lift pump
is fitted on each side of the dividing wall.
They are secured with stainless steel pipe clamps. The upper
fastening point should be in the topmost segment of the
dividing wall and the lower one in the first segment of the
lower part of the dividing wall.
The lift pump’s intake points should be 5 cm above the tank
base. The intake points should be arranged such that they
are evenly distributed over the base area.
The tank connection for the sludge return line is connected to
the dome shaft. Holes on the dome shaft are made in the
factory. Each final sedimentation tank has its own sludge
return line. The individual sludge return lines are combined to
form one pipe. The sludge is returned to the second
preliminary sedimentation tank. A DN 87.5° (DN 100) waste
water bend should be attached to the pipe in the dome shaft
with its opening at the top to prevent excess sludge from
flowing back.
This bend positions the inlets from the excess sludge lifters.
