WPL Diamond DMC, Operation & Maintenance Manual

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2. HOW THE DIAMOND WORKS
2.1 Operating Conditions
The plant is designed to operate automatically with the minimum
of maintenance after it has been commissioned. The plant will provide
e
ffl uent within the designed discharge consent standard after an initial
start up period of 4-10 weeks, depending on the water temperature. It
is important that the sewage input conditions are kept within the plant
design criteria, including the population equivalent (as set by British
Water).
2.2 Inside the Diamond
The Diamond system consists of two treatment chambers in a single
tank. The central aeration chamber is a circular tank with a sloped,
open bottom which empties into the bottom of the outer clari
fi er
chamber. Located in the centre of the aeration chamber is a circular
draft tube, which extends towards the bottom of the clari
fi er.
2.3 The Treatment Process
Air is released at the bottom of the draft tube through a disc plate
di
ff user and as the di ff used air rises in the draft tube, it causes an
upward fl ow of process fl uid. This draws the settled solids from the
bottom of the clari fi er up through the draft tube where they are
discharged at the surface of the aeration chamber. The design of the
draft tube ensures continuous and complete mixing of oxygen with the
sewage, allowing for the growth of various aerobic organisms that
biologically degrade the wastewater contaminants.
Gravity causes the aerated solids to settle back to the bottom of the
tank where they are again drawn back up through the draft tube. As
raw sewage enters the aeration chamber it displaces biological solids
from the aeration chamber to the clari
fi er. Quiescent conditions in the
clari fi er allow the digested solids to settle to the bottom of the clari fi er
where they are again returned back to the aeration compartment.
The clari fi ed (treated) e ffl uent fl ows slowly up through the clari fi er it is
then discharged through a 110mm-pipe connection. A ‘T’ connector, fi tted
to the outlet pipe, prevents fl oating solids from passing out of the plant.
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