and 0.026 L/s 600 GPD for plants of more than 6.60
L/s 150,000 GPD capacity. For step aeration type,
insert 0.026 L/s 600 GPD. For complete mixing type,
insert 0.02 L/s 50 GPD.
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NOTE: Delete reference to mechanical sludge
collector for extended aeration type of 4.38 L/s
100,000 GPD capacity and less and for step aeration
type of 3.0 L/s 67,500 GPD capacity and less.
**************************************************************************
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NOTE: Delete reference to mixing with aeration tank
contents for extended aeration type and step
aeration type.
**************************************************************************
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NOTE: Delete reference to mechanical aeration when
step aeration type or complete mixing type is
specified, or when not allowed for extended aeration
type. Mechanical aerator may not be suitable for
use in areas having prolonged periods of
sub-freezing temperatures when spray may form
accumulation of ice. Consideration should be given
to temperature and detention time of the liquid and
freeboard in the tank in determining temperatures
that may be tolerated. Mechanical aerator is not
suitable for extended aeration type where eventual
conversion to step aeration is contemplated.
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The Sewage Treatment Plant shall be capable of treating an average design
flow of [_____] L/s gallons per day of domestic sewage, having a 5 day
(BOD) loading of [_____] milligrams/liter (mg/l) and total suspended solids
of [_____] mg/l. The raw sewage shall first pass through a [comminutor]
[screening basket] [and an influent distribution channel] into an aeration
tank of adequate capacity to provide [not less than [_____] hours detention
time and] a maximum organic loading not to exceed [_____] kg per 1000 cubic
meter [_____] pounds 5 day BOD per 1,000 cubic feet of aeration tank volume
at average design flow rate. Sewage shall then pass on to a settling tank
of adequate capacity to provide [not less than [_____] hours detention time
and] a surface settling rate not to exceed [_____] L/s per square meter GPD
per square foot at average design flow rate. The settled sludge shall [be
collected by a mechanical sludge collector and] be recirculated back to the
aeration tank [where it is to be rapidly and thoroughly mixed in with the
aeration tank contents,] or wasted to the aerobic digester. The effluent
from the settling tank shall be discharged to a chlorine contact tank of
adequate capacity to provide a detention time of not less than 15 minutes
at peak flow and then to outfall. The aerobic digester shall have a
capacity of not less than 0.057 cubic meter 2 cubic feet per capita.
Aeration shall be by diffused air [or mechanical aeration].
3.2
SLUDGE COLLECTION AND TRANSFER SYSTEM [AND RETURN SLUDGE MIXING]
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NOTE: Delete wording within brackets, except for
SECTION 11375N
Page 97
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