558
P. Farkas
Application ofSTOD measurements in the detection of substrate leak-through
For this purpose an instrument published on the IVth IAWPR Conference was
employed [3]. In a sludge sample aerated at constant rate, the equilibrium 0 2 deficit is
continuously monitored. If there is any unremoved substrate in an effluent sample added
to this system, a peak on the oxygen curve will result, the area under which will be
proportional to its BOD. Calibration is made by adding a known amount of acetate (or
other substrate), Ac to the system whose oxygen equivalent, K? is known and found
constant [14, 15].
Effluent soluble BOD can be calculated with the following formula:
K r A c F w
BOD=
V w Fac
where F w and F a c are the respective peak areas for waste and acetate, V w is the added
waste volume (effluent or influent), and, for acetate, K| = 0,5.
The above method — as all other STOD procedures - does not yield results coincident
with dilution BOD 5 results, but agrees mostly with the BOD 5 of filtered samples. One
measurement rarely takes more than one hour, and can be performed by unskilled
personnel more successfully than the original STOD method published by Vernimmen et
al[9].
Application of plant loading control
For the treatment of pigfarm wastes, a technology consisting of lime precipitation and
subsequent biological treatment is now being developed in Hungary [16]. In a pilot scale
unit, a breakdown was encountered, due to lime overdosing. Prior and after the
breakdown, AR/AS and effluent soluble substrate measurements were performed, and the
results included in Table 3. As a consequence of pH rise in the sludge liquor, AR/AS fell
from 109 to 10 mg"
1 1 xlO
3 , accordingly the effluent substrate rose from 20 to 190 mg/1
BOD, a sign of SSLT, as measured by the described STOD procedure. Filtered sample
dilution BOD 5 values yield similar results. SSLT obviously came from overloading or
poisoning by high pH, but the poisoning effect (negative AR/AS value) became apparent
only on the application of a higher test load of AS = 200 mg/1 COD.
Prediction of effluent quality
To a municipal treatment plant, the effluent of a pharmaceutical factory was
discharged. The latter had two units, No. 1 (B 12 fermentation) and No. 2 (fine chemicals
production). Waste flow and concentration data were as follows:
Original effluent flow
Effluent concentration
Discharge flow of Unit No. 1
Concentration, Unit No. 1
S m
= 2,7 kg/m
3 COD
Removal efficiency for discharge of Unit No. 1
(lab-scale tests)
Discharge flow of Unit No. 2
Concentration thereof
Removal efficiency
(lab-scale tests)
q
S e
qi
Soi
T?l
q2
So2
7?2
= 4000m
3 /d
= 0,40 kg/m
3
= 200m
3 /d
= 2,7 kg/m
3 (
= 0,72
= 450m
3 /d
= 4,0 kg/m
3
= 0,6
P. Farkas
Application ofSTOD measurements in the detection of substrate leak-through
For this purpose an instrument published on the IVth IAWPR Conference was
employed [3]. In a sludge sample aerated at constant rate, the equilibrium 0 2 deficit is
continuously monitored. If there is any unremoved substrate in an effluent sample added
to this system, a peak on the oxygen curve will result, the area under which will be
proportional to its BOD. Calibration is made by adding a known amount of acetate (or
other substrate), Ac to the system whose oxygen equivalent, K? is known and found
constant [14, 15].
Effluent soluble BOD can be calculated with the following formula:
K r A c F w
BOD=
V w Fac
where F w and F a c are the respective peak areas for waste and acetate, V w is the added
waste volume (effluent or influent), and, for acetate, K| = 0,5.
The above method — as all other STOD procedures - does not yield results coincident
with dilution BOD 5 results, but agrees mostly with the BOD 5 of filtered samples. One
measurement rarely takes more than one hour, and can be performed by unskilled
personnel more successfully than the original STOD method published by Vernimmen et
al[9].
Application of plant loading control
For the treatment of pigfarm wastes, a technology consisting of lime precipitation and
subsequent biological treatment is now being developed in Hungary [16]. In a pilot scale
unit, a breakdown was encountered, due to lime overdosing. Prior and after the
breakdown, AR/AS and effluent soluble substrate measurements were performed, and the
results included in Table 3. As a consequence of pH rise in the sludge liquor, AR/AS fell
from 109 to 10 mg"
1 1 xlO
3 , accordingly the effluent substrate rose from 20 to 190 mg/1
BOD, a sign of SSLT, as measured by the described STOD procedure. Filtered sample
dilution BOD 5 values yield similar results. SSLT obviously came from overloading or
poisoning by high pH, but the poisoning effect (negative AR/AS value) became apparent
only on the application of a higher test load of AS = 200 mg/1 COD.
Prediction of effluent quality
To a municipal treatment plant, the effluent of a pharmaceutical factory was
discharged. The latter had two units, No. 1 (B 12 fermentation) and No. 2 (fine chemicals
production). Waste flow and concentration data were as follows:
Original effluent flow
Effluent concentration
Discharge flow of Unit No. 1
Concentration, Unit No. 1
S m
= 2,7 kg/m
3 COD
Removal efficiency for discharge of Unit No. 1
(lab-scale tests)
Discharge flow of Unit No. 2
Concentration thereof
Removal efficiency
(lab-scale tests)
q
S e
qi
Soi
T?l
q2
So2
7?2
= 4000m
3 /d
= 0,40 kg/m
3
= 200m
3 /d
= 2,7 kg/m
3 (
= 0,72
= 450m
3 /d
= 4,0 kg/m
3
= 0,6