496
W.W. Eckenfelder, Jr., C D . Magee and C.E. Adams, Jr.
The transfer coefficient, a, must be estimated from laboratory or field studies (18). The
required horsepower is the oxygen requirement computed from (10) divided by N,
computed from (16).
14. Check the power level (HP/MG) in each basin. If the power level is too low to
maintain all solids in suspension, the retention time should be recalculated using
Equation (6) or (7) also considering basin temperature. Under conditions of solids
deposition the feedback BOD must be considered.
15. The total effluent BOD, considering effluent suspended solids, is computed from
Equation (8).
Because of the lack of specific information at this time, the designer must judge
whether complete mixing conditions will prevail in the basin. In general pov/er levels of
14-20 HP/MG will provide complete mixing for most applications; however, power levels
as low as 4 HP/MG may result in complete mixing when the concentration of BOD and
suspended solids entering the basin is low.
This design procedure was applied to a pulp and paper mill wastewater with the
following design inputs:
Flow-5MGD
a
- 0.5
BOD-300 mg/1
a' - 0.52
Wastewater temperature - 100°F b
- 0.2
Mean air temperature - 20°F
k
- 0.015
Basin depth- 15 ft
The degradable fraction of the volatile suspended solids (x) in the basin has been
estimated as 0.72 for one day retention and 0.66 for three days retention. The results are
summarized in Fig.5. The required effluent soluble BOD is 50 mg/1 under the winter
operating conditions specified above.
NOMENCLATURE
S e
=
soluble effluent BOD (mg/1)
S Q
=
influent BOD (mg/1)
K
=
overall removal rate coefficient
Xy
=
aeration volatile suspended solids (mg/1)
x
=
active mass
k
=
BOD removal rate coefficient (1/mg-hr)
t
=
detention time (days)
a
=
sludge yield coefficient, i.e. fraction of BOD removed used for cellular
synthesis
b
=
cellular auto-oxidation rate coefficient (days"
1 )
β
=
feedback factor
D
=
depth of lagoon
Tj
=
influent temperature (°F)
T w
=
basin temperature (°F)
T a
=
average ambient air temperature (°F)
f
=
proportionality factor
a'
=
oxygen consumed per unit substrate removed
W.W. Eckenfelder, Jr., C D . Magee and C.E. Adams, Jr.
The transfer coefficient, a, must be estimated from laboratory or field studies (18). The
required horsepower is the oxygen requirement computed from (10) divided by N,
computed from (16).
14. Check the power level (HP/MG) in each basin. If the power level is too low to
maintain all solids in suspension, the retention time should be recalculated using
Equation (6) or (7) also considering basin temperature. Under conditions of solids
deposition the feedback BOD must be considered.
15. The total effluent BOD, considering effluent suspended solids, is computed from
Equation (8).
Because of the lack of specific information at this time, the designer must judge
whether complete mixing conditions will prevail in the basin. In general pov/er levels of
14-20 HP/MG will provide complete mixing for most applications; however, power levels
as low as 4 HP/MG may result in complete mixing when the concentration of BOD and
suspended solids entering the basin is low.
This design procedure was applied to a pulp and paper mill wastewater with the
following design inputs:
Flow-5MGD
a
- 0.5
BOD-300 mg/1
a' - 0.52
Wastewater temperature - 100°F b
- 0.2
Mean air temperature - 20°F
k
- 0.015
Basin depth- 15 ft
The degradable fraction of the volatile suspended solids (x) in the basin has been
estimated as 0.72 for one day retention and 0.66 for three days retention. The results are
summarized in Fig.5. The required effluent soluble BOD is 50 mg/1 under the winter
operating conditions specified above.
NOMENCLATURE
S e
=
soluble effluent BOD (mg/1)
S Q
=
influent BOD (mg/1)
K
=
overall removal rate coefficient
Xy
=
aeration volatile suspended solids (mg/1)
x
=
active mass
k
=
BOD removal rate coefficient (1/mg-hr)
t
=
detention time (days)
a
=
sludge yield coefficient, i.e. fraction of BOD removed used for cellular
synthesis
b
=
cellular auto-oxidation rate coefficient (days"
1 )
β
=
feedback factor
D
=
depth of lagoon
Tj
=
influent temperature (°F)
T w
=
basin temperature (°F)
T a
=
average ambient air temperature (°F)
f
=
proportionality factor
a'
=
oxygen consumed per unit substrate removed