[3.2.1
Sludge Transfer
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NOTE: Delete wording within brackets, except for
complete mixing type.
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Sludge transfer shall be accomplished by one of the following methods:
a.
Separate pumps for return sludge and waste sludge with valved
control on discharge side.
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NOTE: Delete item (b) except for extended aeration
type.
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[b.
One pump with valved connections for return sludge and waste
sludge.]
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NOTE: Delete item (c) for complete mixing type.
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[c.
One pump discharging to sludge division box for return sludge and
waste sludge.]
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NOTE: Delete item (d) in its entirety for step
aeration type and for extended aeration type when
eventual conversion to step aeration is
contemplated; delete wordings in brackets within (d)
for extended aeration type; retain item (d) in its
entirety for complete mixing type.
**************************************************************************
[d.
Traveling pump discharging [directly into aeration tank and] into
[waste sludge] trough with movable divider plate for proportioning
return sludge and waste sludge.]
Discharge piping from sludge transfer pump(s) shall be not less than 75 mm
3 inches in diameter, flanged, and arranged to maintain a velocity of not
less than 0.61 meters per second 2 feet per second when sludge pump(s) are
operating at normal rates. Valves on return sludge and waste sludge piping
on the downstream side of sludge transfer pumps shall be gate valves or
plug valves. Materials for piping and valves shall be as specified in
paragraph entitled "Piping." Sludge division box or trough shall be as
specified under paragraph entitled "Appurtenances and Accessories."
]3.2.2
Return Sludge Mixing
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NOTE: Delete paragraph except for complete mixing
type.
**************************************************************************
A positive means shall be provided for the thorough and rapid mixing of
return sludge with aeration tank contents. One of the following means
shall be provided:
SECTION 11375N
Page 99
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