Oct - Dec 2009 • Vol. No. 32 Issue No. 2 • - L&T Construction

Raw water receiving cum distribution
chamber
The receiving chamber is a reinforced cement
concrete structure. The raw water flows through
the mains of 2400mm pipes at the inlet tank of
the treatment plant. The top of the chamber is
accessible by the general walkway along the
Clarifier distribution chamber
Provision has also been made (with the help of
Penstocks and RCC Channel) to bypass the clarifiers
for direct feed to filters.
The water from the clarifier is filtered in a battery of 18
gravity-operated filters.
measuring channel. The receiving chamber has The filter plant includes two rows of filters each with a
been connected to the drainage system by 151.4 m² useful surface area. These are covered by a
means of a wall duct with gate valve. A mild steel central gallery for housing the individual filter
ladder has been provided in the chamber to consoles.
access the bottom.
Water from measuring channel enters the clarifier
distribution chamber. The inlet and outlet of the
Parameters
Aquazur V filter : 18 numbers
(15.14 m x 5 m twin bed)
Size : 112 m x 50m x16 m
distribution chambers are designed to provide Plan area : 5600 sq.m
overflow in clarifier distribution box.
Concrete : 7690 cu.m
The Distribution Chamber has been provided with
two compartments, Inlet Compartment and Overflow
Compartment to reduce short-circuiting and to
enable dispersion of chemicals. Each Compartment
is isolated with the help of Penstocks.
Raw water distribution & clarified water collection are
perpendicular with respect to the sludge blanket. This
clarifier is a flat bottom sludge blanket of pulsator type.
Raw water feed takes place through perforated pipes at
the bottom with PVC stilling plates. Air blowers are used
to pulsate the water within the range of 0.6 m to 1 m
using sequential short flushes & prolonged periods of
rest (20 – 40 sec) alternately, hence ensuring sludge
blanket expansion. Automatic sludge draw-off takes
place at the sludge Blanket level. Clear water collection
is through perforated V troughs at the top. Pulsators
have maximum flexibility in case of variable raw water
flow rate and quality of water. It has no submersible
moving mechanical equipment. There is substantial
saving of chemicals is achived due to strong
flocculation in the sludge blanket. Sludge blanket acts
as an absorbent filter which is highly efficient as far as
the removal of colloids and plankton / algae are
concerned .
Filtration
Form work : 36000 sq.m
Reinforcement : 650 t
Parameter Dimension Capacity
Receiving Chamber 28 x25 x 4 700 sq m
Main Distribution Chamber 8.5 x 7.5 x 6 63.75 sq m
Parshall flume with channel 66 x 6.2 x4 409.2
Design Flow 1060 mld
Stage I 624 mld
Stage II 436 mld
Features
An open channel parshall flume with ultra sonic level sensor
Electrically operated penstock at the end of the chamber for the
pulsator distribution chamber.
Alum injection through feeder pipe ensures thorough mixing in the
inlet chamber.
Pre-chlorination through submerged PVC perforated pipes which
are easily detachable for maintenance without disturbing the flow.
PLC controlled on-line water analyzer for the measurement of
ph and turbidity of the raw water.
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ECC Concord Oct-Dec 09