406
W. Torpey, H. Heukelekian, A.J. Kaplovsky, and R. Epstein
Enrichment of the atmosphere over the specific stages was accomplished by enclosing
the disk assembly above the water surface with 1,27 cm thick transparent plexiglass
placed in a box-like form to provide a sealed hood. Oxygen was fed at 0.5 to 2-liters per
minute and gas pressure was maintained between 0 to 2.54 cm of water. The hood was
found to have small leaks which, in conjunction with a pressure of less than 0.32 cm of
water under the hood, were able to transmit the nitrogen evolved from the wastewater
and the C0 2 generated by respiration.
The carbon adsorption system consisted of six packed bed columns 1.78m long and
7.62 cm in diameter. About 10.08 Kg of virgin granular carbon (12 x 40 mesh) was used
resulting in a bed expansion of about 50% during the daily backwashing operation. The
pressure across the six columns, operated in series, at first was found to increase at a rate
of about 2,812 Kgs/m
2 in 24 hours until the mixed media filter was interposed and the
rate was lowered to less than 703.1 Kgs/m
2 in 24 hours.
Samples of influent were taken between 3 and 6 p.m. and prepared for analysis by
microstraining through a 5.08 cm diameter 35 micron "hand" microstrainer.
OPERATING RESULTS
A. Organic Removal in Terms of B.O.D. s
From previous investigations (Torpey et al 1971) the effluents from stages 3 to 10
were known to contain from 2 to 5 mg/1 of dissolved oxygen, yet from stages 1 and 2
they were generally devoid of dissolved oxygen. The oxygen demand of the slimes in the
upper two stages were not being satisfied. As a means of overcoming this limitation, stage
1 was modified by increasing the number of disks from 48 to 60 and installing a hood for
oxygen enrichment studies. Oxygen gas, fed at 1.5 liters/min., increased the percentage of
oxygen under the hood of stage 1 from 50% to 70%. The dissolved oxygen in the effluent
from this stage varied between 8 and 14 mg/1, and provided oxygen for stage 2.
Coincident with the changes to stage 1 equipment, the disks in stage 2 were increased
from 48 to 71.
Data obtained for the base period, July to November, 1969, as to the B.O.D. 5 in the
effluents from the 10 stages is shown in Fig. 1. The influent B.O.D. 5 of 124 mg/1 was
reduced progressively to 19 mg/1 at stage 5. Thereafter the rate of removal decreased and,
at stage 10, to 9 mg/1.
Also shown in Fig. 1 is the profile of B.O.D. 5 when stage 1 was equipped with a hood.
This data was obtained under the same flow conditions as the base period. The B.O.D.5
of 101 mg/1 in the influent was reduced to 35 mg/1 by stage 1 alone and to 16 mg/1 after
stage 3. During treatment through stages 4 to 6, the rate of removal of B.O.D. 5 decreased,
and remained at 12 mg/1 after stage 6.
The stability of the process with respect to the B.O.D.5 remaining after the various
stages is evident from the daily maximum, minimum and average values for influent and
the stage effluents. In general the B.O.D. s of the downstream stage effluents varied from
one half to twice the average.
W. Torpey, H. Heukelekian, A.J. Kaplovsky, and R. Epstein
Enrichment of the atmosphere over the specific stages was accomplished by enclosing
the disk assembly above the water surface with 1,27 cm thick transparent plexiglass
placed in a box-like form to provide a sealed hood. Oxygen was fed at 0.5 to 2-liters per
minute and gas pressure was maintained between 0 to 2.54 cm of water. The hood was
found to have small leaks which, in conjunction with a pressure of less than 0.32 cm of
water under the hood, were able to transmit the nitrogen evolved from the wastewater
and the C0 2 generated by respiration.
The carbon adsorption system consisted of six packed bed columns 1.78m long and
7.62 cm in diameter. About 10.08 Kg of virgin granular carbon (12 x 40 mesh) was used
resulting in a bed expansion of about 50% during the daily backwashing operation. The
pressure across the six columns, operated in series, at first was found to increase at a rate
of about 2,812 Kgs/m
2 in 24 hours until the mixed media filter was interposed and the
rate was lowered to less than 703.1 Kgs/m
2 in 24 hours.
Samples of influent were taken between 3 and 6 p.m. and prepared for analysis by
microstraining through a 5.08 cm diameter 35 micron "hand" microstrainer.
OPERATING RESULTS
A. Organic Removal in Terms of B.O.D. s
From previous investigations (Torpey et al 1971) the effluents from stages 3 to 10
were known to contain from 2 to 5 mg/1 of dissolved oxygen, yet from stages 1 and 2
they were generally devoid of dissolved oxygen. The oxygen demand of the slimes in the
upper two stages were not being satisfied. As a means of overcoming this limitation, stage
1 was modified by increasing the number of disks from 48 to 60 and installing a hood for
oxygen enrichment studies. Oxygen gas, fed at 1.5 liters/min., increased the percentage of
oxygen under the hood of stage 1 from 50% to 70%. The dissolved oxygen in the effluent
from this stage varied between 8 and 14 mg/1, and provided oxygen for stage 2.
Coincident with the changes to stage 1 equipment, the disks in stage 2 were increased
from 48 to 71.
Data obtained for the base period, July to November, 1969, as to the B.O.D. 5 in the
effluents from the 10 stages is shown in Fig. 1. The influent B.O.D. 5 of 124 mg/1 was
reduced progressively to 19 mg/1 at stage 5. Thereafter the rate of removal decreased and,
at stage 10, to 9 mg/1.
Also shown in Fig. 1 is the profile of B.O.D. 5 when stage 1 was equipped with a hood.
This data was obtained under the same flow conditions as the base period. The B.O.D.5
of 101 mg/1 in the influent was reduced to 35 mg/1 by stage 1 alone and to 16 mg/1 after
stage 3. During treatment through stages 4 to 6, the rate of removal of B.O.D. 5 decreased,
and remained at 12 mg/1 after stage 6.
The stability of the process with respect to the B.O.D.5 remaining after the various
stages is evident from the daily maximum, minimum and average values for influent and
the stage effluents. In general the B.O.D. s of the downstream stage effluents varied from
one half to twice the average.