PHOSPHATE REMOVAL BY ACTIVATED SLUDGE
Amenability Studies at
Cleveland, Ohio
by
L. D. Lively, J. A. Horn, M. R. Scalf,
F. M. Pfeffer, J. L. Witherow, and C. P. Priesing*
*The authors are, respectively, Research Chemist, Research Sanitary
Engineer, Research Sanitary Engineer, Research Chemist, Research
Sanitary Engineer, and Acting Chief, Treatment and Control Research
Program, Robert S. Kerr Water Research Center, Federal Water Pollution
Control Administration, U. S. Department of the Interior, Ada,
Oklahoma.
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TABLE OF CONTENTS
Item Page
ABSTRACT ill
INTRODUCTION 1
Experimental Procedures 2
RESULTS AND DISCUSSIONS 5
Plant Characteristics 4
Typical Plant Operation 6
Plant Monitoring 7
Aeration Jug Studies 16
Sewage Characterization 33
Microbiological Studies 35
SUMMARY 36
CONCLUSIONS 38
RECOMMENDATIONS 40
APPENDIXES 41
Appendix I 41
Appendix II 45
Appendix III 49
Appendix IV 50
ACKNOWLEDGEMENT 54
TABLES
1. Plant Operating Data 7
2. Plant Monitoring Data 15
3. Extensive Plant Performance Data 17
4. Suspended Solids Variation—Components 18
5. Suspended Solids Variation—Results 19
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Item
TABLES (Continued)
6. BOD Variation—Components
7. BOD Variation—Results
8. Orthophosphate Variation
9. Chemical Addition
10. Aeration Tank-Jug Simulation . . . .
11. Acclimation-Control Comparison . . .
FIGURES
1. Plant Layout Sheet
2. Dye Detention in Aeration Tanks . . .
3. Dye Detention-Final Clarifier No. 9 .
4. Dye Detention-Final Clarifier No. 14
5. Dissolved Oxygen-Aeration Tanks . . .
6. Orthophosphate Removal vs. MLSS . . .
7. TOC-BOD Relationships
8. Phosphate Variation-Aeration Jugs . .
9. Chemical Addition-Aeration Jugs . . .
10. Aeration Tank and Jug Comparisons . .
22
23
26
29
31
34
5
9
11
12
13
21
25
27
30
32
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Ill
ABSTRACT
Phosphate removal by activated sludge was investigated in pilot-
and plant~scale research conducted at the Cleveland, Ohio Easterly
Pollution Control Center. These studies showed that the aeration
tanks were averaging 25 percent removal of the orthophosphate in the
tank influent. The following conditions were different from those
found in the San Antonio Rilling Plant: (1) biochemical oxygen demand
(BOD) and orthophosphate (as P) levels in the primary effluent (PE) were
much lower, averaging 125 and 2.5 mg/1, respectively; (2) mixed liquor
suspended solids (MLSS) concentrations were higher, ranging from 1,500
to 2,500 mg/1; (3) BOD loadings were lower, ranging from 0.20 to 0.35
lb./lh MLSS/day; and (4) aeration tank dissolved oxygen (DO) profiles
were characteristic of the tapered aeration practiced. Mixed liquor
aeration and operation of the final clarifiers were similar to those
of the Rilling Plant.
Pilot investigations were made to determine the amenability of
the waste and activated sludge to phosphate removal. A slight increase
in removal was observed with increasing MLSS or oxygen-demanding
substrate concentration. Ferric iron or aluminum salt addition caused
high orthophosphate removals. Orthophosphate addition resulted in
reduced removal efficiency. After an acclimation period of 18 to
42 hours, the sludge removed significant quantities of orthophosphate.
Excluding the chemical addition studies, the maximum removal efficiency
was 67 percent. The waste and sludge were concluded as only "moderately"
amenable to phosphate removal.
A plant trial should be undertaken to optimize operating conditions
essential for phosphate removal prior to final commitment of this
facility as a biological phosphate removal demonstration site. This
is recommended because of the "moderate" amenability attained in pilot
studies and the marked differences in loading and operating parameters
with the San Antonio Rilling Plant.
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INTRODUCTION
This report describes investigations at the Easterly Pollution
Control Center, Cleveland, Ohio, in a continuing research program
concerned with the removal of phosphate from municipal sewage by
the activated sludge process. Field research conducted at San
Antonio, Texas, established that high removals of orthophosphate
from the liquid to the mixed liquor solids were accomplished in
the aeration tanks. The efficiency of the process was controlled
by the operational parameters: aeration detention time, air
supplied, mixed liquor suspended solids concentration, BOD load,
phosphate load, rapid solid-liquid separation, and separate
phosphorus disposal in the final clarifiers.
The purposes of the amenability studies conducted were:
1. To determine if biological phosphate uptake is feasible in
municipalities of various geographical locations, populations served,
and sewage characteristics by pilot and plant investigations.
2. To locate six or more activated sludge plants in various
geographical regions to be used for demonstration of biological
phosphate removal by operation in accordance with parameters
identified at San Antonio.
3. To locate one activated sludge plant of suitable design
and operational flexibility for use as a full-scale research plant
to further specify, define, and optimize the biological phosphate
removal process.
4. To verify on pilot scale that biological phosphate removal
can be controlled by the parameters identified at San Antonio1 and/or
isolate and identify additional controlling parameters.
Aerated jugs of mixed liquor previously shown to simulate an
aeration tank circumvent many of the limitations exerted by normal
operational characteristics in activated sludge plants, such as
control of aeration rate, sewage flow, suspended solids concentration,
and phosphate and BOD loadings. Sludge solids and waste from various
points in the secondary system may be conveniently studied. Detention
ipriesing, C. P., et al., "Phosphate Removal by Activated Sludge—
Pilot Research," Robert S. Kerr Water Research Center, Ada, Oklahoma.
Presented October 11, 1967, New York WPCF Meeting.
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time of the mixed liquor in the aerated jug system is rigidly controlled.
For these reasons, the method was selected for testing the amenability
of the waste and activated sludge to phosphate removal.
By deliberate variation of the operational parameters, the conditions
for sludge response and maximum phosphate removal can be established.
Amenability studies will indicate those waste and activated sludges most
readily adaptable and, that, in conjunction with plant investigations,
will aid in specifying operational levels, design changes, or time for
sludge adaptability necessary to attain phosphate removal in the full-
scale plant.
Experimental Procedures
Plant Analysis
The plant was studied to determine pertinent design and opera-
tional characteristics and performance. Plant records were examined
for type and frequency of sewage flow, plant loading of BOD, suspended
solids, and orthophosphate concentrations, analyses of chemical and
physical parameters, and performance characteristics. Typical data
are presented in Appendix II. Plant personnel were questioned about
sampling practices, analytical procedures, anomalies of wastes being
treated, and peculiarities of operational control. The schedules for
wasting raw and activated sludges were determined. Disposal methods
of waste activated sludge, primary sludge, digester supernatant, sludge
thickener supernatant, drying bed underflow, and other waste streams
were studied in anticipation of auxiliary, inhibitory, or latent
effects on the phosphate removal process.
Tracer studies were conducted using Rhodamine WT dye in aeration
tanks and final clarifiers to determine hydraulic characteristics such
as detention, short circuiting, and degree of longitudinal mixing.
Grab samples were collected throughout the plant to determine
the phosphate levels and degree of removal. These samples were
analyzed for orthophosphate concentration and, occasionally, for
total phosphate and total suspended solids (TSS). Chemically fixed
samples were sent to the Robert S. Kerr Water Research Center at Ada,
Oklahoma, for total phosphate and chemical oxygen demand (COD). The
sample sources were: raw sewage, PE, return sludge (RS), aeration
tank influent, aeration tank effluent, and final effluent. Occas-
ionally, supernatant samples were taken from sludge thickeners. DO
measurements were made throughout the plant in conjunction with the
sampling program. When these studies indicated that phosphate was
being removed, more detailed sampling on a slug-flow basis was
undertaken to specify the magnitude of removal.
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Aeration Jug Studies
Return sludge or mixed liquor from various points in the sec-
ondary system was mixed with primary effluent or raw sewage to obtain
the desired range of suspended solids concentration. The mixtures
were prepared in five-gallon polyethylene jugs for subsequent
aeration.
A portable air compressor was used as the air supply. Air was
delivered through a manifold containing individual needle valves and
rotometers for each jug. Polyethylene tee fittings were used as
diffusers. The air flow was maintained constant throughout the
experiment, except where noted.
Dissolved oxygen content and temperature of the mixed liquor
were monitored several times during each run.
Samples were withdrawn from the jugs usually at half-hour or
hourly intervals. Preceding sample collection, approximately 200 ml
of mixed liquor was siphoned through the Tygon withdrawal tube for
purging and returned to the original jug. A volume of 100 ml was
sufficient for orthophosphate determination, and 250 ml was taken
when additional analyses were planned.
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RESULTS AND DISCUSSIONS
Plant Characteristics
The Easterly Cleveland Sewage District reaches along Lake Erie
from the mouth of the Cuyahoga River to East 185th Street and includes
city and suburban areas which drain northward to the lakes. The
population served is approximately 603,000.
The present activated sludge plant was designed to treat an
average sewage flow of 123 million gallons per day (mgd). The
existing plant was constructed in 1937 with the exception of the
standby bar screens and grit chambers which were part of the
original installation built in 1920-1922. The removal of TSS and
BOD throughout the plant averages approximately 85 and 90 percent,
respectively. The plant layout and flow sequence are shown in
Figure 1.
Sewers in the Easterly Cleveland District are combined sanitary-
storm sewers. Preliminary treatment facilities consist of comminutors,
detritus tanks, and preaeration tanks to grind solids, remove grit, and
flocculate oil and grease. Primary treatment facilities consist of 8
rectangular clarifiers, each 115' x 50' x 15' liquid depth. Sludge and
scum are collected and pumped to the Southerly Cleveland Sewage Treatment
Plant for processing and disposal.
Secondary treatment facilities incorporate the conventional acti-
vated sludge process. The aeration units consist of 16 double-pass,
rectangular tanks built in four separate batteries of four tanks each.
Each pass is 334 feet long by 27 feet wide by 15 feet liquid depth.
The design flow is 123 mgd of primary effluent with 31 mgd of return
sludge. The displacement time is five hours at design flow. Aerated
channels transport primary effluent and return sludge to and take
mixed liquor from the aeration tanks.
Three 40,000-cfm and two 25,000-cfm centrifugal multistage blowers
provide process air. Air flow is controlled and metered to each
aeration tank separately by cone control valves and Venturi meters.
In each double-pass tank, air diffusers consist of 1,184 12" x 12" x 1"
aluminum oxide plates having a permeability range of 30 to 60. The
ratio of plate surface to tank liquid surface is approximately 1 to
10. The plates are positioned in two adjacent rows extending along
one side wall to produce a spiral-roll flow pattern. At a spacing
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Comminutor ft Grit Chamber
Preaeration
Excess Sludge
Activated Sludge
Thickners
Primary Clarifiers
— Primary Effluent
Final
Effluent
FIGURE I-PLANT LAYOUT SHEET, CLEVELAND, OHIO
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of 64 feet 3 inches, rows consisting of nine plates extend 10 feet
transversely beyond the inner row of longitudinal plates. These
transverse aerators were installed to prevent hydraulic short
circuiting. Valves are located at 25-foot intervals to allow
variation of air distribution within the tank. Separate valves
control the air supply to the transverse aerators.
Final clarification facilities consist of 16 circular tanks,
each 112 feet in diameter and having a 12-foot side-water depth with
center inlets. The 16 tanks are separated into four batteries of
four tanks each. The weir length of each tank is 340 feet. The
final clarifiers are not equipped with inlet baffling.
Return sludge pumping facilities consist of four variable speed
pumps each having a capacity range of 4.7 to 10 mgd. Two standby
pumps of equal capacity are available. The return sludge is mixed
with primary effluent prior to introduction into the aeration tanks.
The secondary treatment facilities can be operated as one plant,
as two 8-tank battery plants, or as four 4-tank battery plants. It
is possible to completely isolate batteries from each other, including
return sludge flow. The return sludge flow from each clarifier can
be sampled and monitored independently.
Activated sludge is wasted from the discharge side of each return
sludge pump. This excess sludge flows into Final Clarifiers NOS. 1
and 2 where it is concentrated by blanket compaction. The concentrated
waste activated sludge flows to the collection sump (Figure 1), where
it mixes with grease and primary sludge and is intermittently pumped
to the Southerly Cleveland Plant for disposal.
Indicating-recording-totalizing meters monitor: (1) primary
effluent inflow and return sludge flow to each 4-tank battery,
(2) waste activated sludge from each 4-tank battery, (3) mixed liquor
flow and air input to each 2-pass aeration tank, (4) air input to
each 2-battery channel aeration system, (5) return sludge flow from
each final clarifier, and (6) concentrated waste activated sludge
being pumped from each final clarifier-sludge concentrator.
Facilities are available to feed chlorine to the raw sewage or
primary clarifier influent for odor control at a maximum rate of
20,000 pounds per day. The plant effluent is disinfected during
June and July.
Typical Plant Operation
Table 1 shows the significant secondary process operational data
extracted from the Easterly Pollution Control Center Annual Report - 1966:
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Table 1
Plant Operating Data
Monthly Average
Max. Min. Avg.
Primary Effluent Flow (mgd) 127.6 103.8 117.7
Mixed Liquor Fow (mgd) 165.3 135.7 153.4
Return Sludge Flow (mgd) 38.2 31.9 35.6
% Return Sludge 35.0 27.8 30.2
Waste Activated Sludge (mgd) 0.52 0.33 0.42
Air Applied (cu. ft./gal.) 1.32 0.96 1.11
The primary effluent normally has a BOD of 125 mg/1 and a
suspended solids concentration of 100 mg/1. The final effluent
contains about 20 mg/1 of BOD and suspended solids.
Phosphate concentrations throughout the plant are routinely
monitored by plant personnel. Monthly report sheets for April-
December 1966 have been included in Appendix II. During this period,
the average concentrations of total phosphate (T-PO.) and dissolved
phosphate were 18.5 mg/1 and 9.5 mg/1, respectively. The removal of
total and dissolved phosphate averaged 16 and 6.3 percent, respectively,
during primary treatment. The corresponding removal efficiencies
during secondary treatment were 33 and 15 percent.
Plant Monitoring
During the study period of April 18-28, 1967, plant operating data
were collected. Due to the large number of treatment units, most of
the survey data were collected on Battery No. 3 which includes aeration
tanks and Final Clarifiers Nos. 9 through 12. Detailed plant operating
data for this battery are given in Appendix III. Twenty-four Hour
charts, collected from the Battery No. 3 meters, monitored mixed
liquor flow from each aeration tank, return sludge flow from each
final clarifier, air flow to each aeration tank, and air provided for
channel aeration. A summary of these data follows:
1. Hydraulic Loading
Dry weather primary effluent flow varied from a peak of 30 to
35 mgd from 12:00 Noon to 2:00 p.m. to a low of 18 to 21 mgd from
5:00 a.m. to 7:00 a.m. Rainfall on April 21-24 altered the diurnal
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8
variation flow for these dates and caused peak flow rates of 40 to
50 mgd. Return sludge flow ranged from 9.5 to 10 mgd during peak
flow conditions to 6 to 7 mgd during periods of low flow. The
percent return sludge was normally 27 to 30 during dry weather flow,
but dropped to a low of 19 during wet weather flows.
2. Dye Tracer Studies
Aeration Tanks - At 1:00 p.m. on April 19, two liters of 20
percent Rhodatnine WT dye was added to the inlet of Aeration Tank No. 9
to determine its flow-through characteristics. Samples were collected
from the 1/4, 1/2, 3/4, and end points of this tank at 15- to 60-tninute
intervals. Dye concentration in these samples was determined by means
of a fluorometer. Effluent sampling discontinued at 6:00 p.m., accounting
for 85 percent of the dye added.
The average mixed liquor flow rate through the 2 million-
gallon aeration tank of 11.1 mgd resulted in a theoretical displace-
ment time of 4.25 hours. Each two-pass aeration tank has a length-
width ratio of 25:1. The average amount of air applied during the
study was 4,800 cubic feet per minute or 0.6 cubic foot per gallon
of mixed liquor.
Figure 2 is a graphical plot of dye concentration at the
half and end points of the aeration tanks and a percent flow-through
for the end point versus the time elapsed after dye addition. The
mode, median, t^g, an<^ t90 (1® an<^ 90 percent flow-through times)
are 3.5, 3.6, 2, and 6 hours, respectively. The dispersion index
(tgo/tio) is 3.0, and the modal detention time is equal to 82 percent
of the theoretical displacement time. The Cleveland aeration tanks
have essentially the same amount of longitudinal mixing and percent
of plug flow as the aeration tanks of the Rilling Plant in San Antonio,
Texas.*
Referring to Figure 2, 10 percent of the mixed liquor receives
less than two hours of aeration and 30 percent less than three hours.
Such flow-through characteristics have been found adequate to allow
80 percent phosphate removal.1 Reducing the hydraulic loading would
lengthen the average detention time and produce conditions more
conducive to phosphate removal if other operating parameters can be
simultaneously adjusted to satisfactory levels. The plant superintendent
indicated that the plant is flexible enough to allow the reduction of
flow to one of the four batteries for an extended period of time without
creating undesirable effluent characteristics.
2Priesing, C. P., et al., "Phosphate Removal by Activated Sludge—Plant
Research," Robert S. Kerr Water Research Center, Ada, Oklahoma.
Presented October 11, 1967, New York WPCF Meeting.
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Factors which influence aeration tank flow-through character-
istics are length-to-width ratio, diffuser design, and compartmentation.
The Cleveland aeration tank length-to-width ratio (25:1) is comparable
to tanks tested in Indianapolis and Baltimore; however, its hydraulic
characteristics are less plug flow in nature when compared to the
results of dye studies conducted at those plants. The presence of
several rows of transverse aerations is unique to the Cleveland tanks.
Dye tracer studies conducted at Mansfield, Ohio, have shown that
transverse aeration increased longitudinal mixing. Plug-flow charac-
teristics might be more closely approached if the transverse aerators
were shut off.
Final Clarifiers - On April 20, one liter of 20 percent
Rhodamine WT dye was added to the inlets of Final Clarifiers Nos. 9
and 14 at 11:00 a.m. and 12:00 noon, respectively. These clarifiers
are located in different batteries. Samples of both clarifier
effluents were collected. The return sludge from Clarifier No. 9
was sampled at the individual sludge well for this clarifier which
is located only a short distance from the sludge outlet. Return
sludge from Clarifiers Nos. 13 through 16 was sampled at the No. 4
battery return box just prior to mixing with primary effluent. There
is little mixing of return sludge between batteries. Total dye
accounted for was 65.5 and 71.8 percent for Clarifiers Nos. 9 and 14,
respectively. Figures 3 and 4 are graphical plots of dye concentration
versus elapsed time after dye addition.
Assuming equal flow distribution, the average mixed liquor
inflow to each 900,000-gallon clarifier was 11.3 mgd. The return
sludge flow from each clarifier was 2.3 mgd. Therefore, the overflow
averaged 9 mgd, and its theoretical displacement time was 2.4 hours.
The modal detention time of the final clarifier overflow was 42 percent
of the theoretical displacement time, indicating typical circular
clarifier performance. The dispersion indices (tgo/t-^g) of the over-
flow from Clarifiers Nos. 9 and 14 were 4.0 and 3.0, respectively,
indicating a greater degree of mixing in Clarifier No. 9. There is
no apparent reason for this difference.
The return sludge sampled at Sludge Well No. 9 had a sharp
peak in dye concentration occur within 10 minutes after dye addition,
indicating limited short circuiting of mixed liquor.
3. Dissolved Oxygen and Sludge Depth
Dissolved oxygen in the aeration tanks was monitored several
times during the study period. Typical DO profiles for Aeration Tanks
Nos. 9 through 12 were plotted in Figure 5. The unit air flow in
these tanks varied from 0.76 to 0.92 cubic foot per gallon of primary
effluent.
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Return Sludge (At Sludge Well)
y-Clorifier Overflow
Theor. Displacement Time
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FIGURE 3-DYE DETENTION- FINAL CLARIFIER NO. 9
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A dissolved oxygen profile was also taken on Aeration Tank
No. 10 on April 27, 1967. DO was measured at the 1/8 points at
staggered time intervals to correlate with the modal time found during
the dye study. This profile was plotted in Figure 10.
The maximum dissolved oxygen level in the aeration tanks was
near the 3/4 point. The DO rapidly decreased throughout the last one-
quarter of the tanks. Such a DO profile would be expected since the
aeration is tapered by one or both of the following methods:
(1) provision of plates having lower permeability from the 3/4 point
to the tank effluent and (2) throttling the air supply to the second
pass to provide a greater amount of air from the tank inlet to the
one-quarter point.
Dissolved oxygen in the final clarifiers was typically 3
to 3.5 mg/1 during the study period. Sludge blanket depths, measured
by an optical density sensor, were 3 inches in the center with none
detectable at the side wall. The DO in the return sludge, monitored
just prior to mixing with primary effluent, ranged from 0.5 to 1.0 mg/1.
This aerobic environment should minimize phosphate release in the final
clarifiers.
On several occasions, during the study period, the final
effluent from Battery No. 3 (Tanks Nos. 9-12) was turbid due to carry-
over of light sludge floe particles. During such periods, the DO in
the clarifier influent was 3 to 3.5 mg/1; however, the DO levels in
these final clarifiers were in the range of 0 to 0.2 mg/1. Due to the
turbidity in the final clarifiers, it was not possible to measure
sludge blanket depth. The presence of suspended sludge in an oxygen-
deficient environment is conducive to phosphate desorption.
The amount of air fed to each aeration tank varied from
4,000 to 5,600 cubic feet per minute. Air to each tank is adjusted
to the maximum possible rate for the existing diffuser condition.
Thus, tanks with cleaner diffusers receive more air. Usually, two
tanks are drained and equipped with clean diffusers each year.
4. Phosphate and Solids Survey
Soluble phosphate levels were determined for each aeration
tank at the influent, 1/2 point, and effluent from 4:00 p.m. to
5:00 p.m. on April 18, 1967. The results of this study, given in
Table 2, show that soluble phosphate removal averaged 25 percent.
In about half of the tanks, the phosphate concentration increased
from the 1/2 point to the effluent. The differences in phosphate
concentration throughout the aeration tanks could have been due to
variation in previous influent concentration.
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A dissolved oxygen profile was also taken on Aeration Tank
No. 10 on April 27, 1967. DO was measured at the 1/8 points at
staggered time intervals to correlate with the modal time found during
the dye study. This profile was plotted in Figure 10.
The maximum dissolved oxygen level in the aeration tanks was
near the 3/4 point. The DO rapidly decreased throughout the last one-
quarter of the tanks. Such a DO profile would be expected since the
aeration is tapered by one or both of the following methods:
(1) provision of plates having lower permeability from the 3/4 point
'to the tank effluent and (2) throttling the air supply to the second
pass to provide a greater amount of air from the tank inlet to the
one-quarter point.
Dissolved oxygen in the final clarifiers was typically 3
to 3.5 mg/1 during the study period. Sludge blanket depths, measured
by an optical density sensor, were 3 inches in the center with none
detectable at the side wall. The DO in the return sludge, monitored
just prior to mixing with primary effluent, ranged from 0.5 to 1.0 mg/1.
This aerobic environment should minimize phosphate release in the final
clarifiers.
On several occasions, during the study period, the final
effluent from Battery No. 3 (Tanks Nos. 9-12) was turbid due to carry-
over of light sludge floe particles. During such periods, the DO in
the clarifier influent was 3 to 3.5 mg/1; however, the DO levels in
these final clarifiers were in the range of 0 to 0.2 mg/1. Due to the
turbidity in the final clarifiers, it was not possible to measure
sludge blanket depth. The presence of suspended sludge in an oxygen-
deficient environment is conducive to phosphate desorption.
The amount of air fed to each aeration tank varied from
4,000 to 5,600 cubic feet per minute. Air to each tank is adjusted
to the maximum possible rate for the existing diffuser condition.
Thus, tanks with cleaner diffusers receive more air. Usually, two
tanks are drained and equipped with clean diffusers each year.
4. Phosphate and Solids Survey
Soluble phosphate levels were determined for each aeration
tank at the influent, 1/2 point, and effluent from 4:00 p.m. to
5:00 p.m. on April 18, 1967. The results of this study, given in
Table 2, show that soluble phosphate removal averaged 25 percent.
In about half of the tanks, the phosphate concentration increased
from the 1/2 point to the effluent. The differences in phosphate
concentration throughout the aeration tanks could have been due to
variation in previous influent concentration.
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A dissolved oxygen profile was also taken on Aeration Tank
No. 10 on April 27, 1967. DO was measured at the 1/8 points at
staggered time intervals to correlate with the modal time found during
the dye study. This profile was plotted in Figure 10.
The maximum dissolved oxygen level in the aeration tanks was
near the 3/4 point. The DO rapidly decreased throughout the last one-
quarter of the tanks. Such a DO profile would be expected since the
aeration is tapered by one or both of the following methods:
(1) provision of plates having lower permeability from the 3/4 point
to the tank effluent and (2) throttling the air supply to the second
pass to provide a greater amount of air from the tank inlet to the
one-quarter point.
Dissolved oxygen in the final clarifiers was typically 3
to 3.5 mg/1 during the study period. Sludge blanket depths, measured
by an optical density sensor, were 3 inches in the center with none
detectable at the side wall. The DO in the return sludge, monitored
just prior to mixing with primary effluent, ranged from 0.5 to 1.0 mg/1.
This aerobic environment should minimize phosphate release in the final
clarifiers.
On several occasions, during the study period, the final
effluent from Battery No. 3 (Tanks Nos. 9-12) was turbid due to carry-
over of light sludge floe particles. During such periods, the DO in
the clarifier influent was 3 to 3.5 mg/1; however, the DO levels in
these final clarifiers were in the range of 0 to 0.2 mg/1. Due to the
turbidity in the final clarifiers, it was not possible to measure
sludge blanket depth. The presence of suspended sludge in an oxygen-
deficient environment is conducive to phosphate desorption.
The amount of air fed to each aeration tank varied from
4,000 to 5,600 cubic feet per minute. Air to each tank is adjusted
to the maximum possible rate for the existing diffuser condition.
Thus, tanks with cleaner diffusers receive more air. Usually, two
tanks are drained and equipped with clean diffusers each year.
4. Phosphate and Solids Survey
Soluble phosphate levels were determined for each aeration
tank at the influent, 1/2 point, and effluent from 4:00 p.m. to
5:00 p.m. on April 18, 1967. The results of this study, given in
Table 2, show that soluble phosphate removal averaged 25 percent.
In about half of the tanks, the phosphate concentration increased
from the 1/2 point to the effluent. The differences in phosphate
concentration throughout the aeration tanks could have been due to
variation in previous influent concentration.
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16
The total suspended solids in the aeration tank varied from
a low of 716 mg/1 in Tank No. 16 to a high of 1,520 mg/1 in Tank No. 7.
Return sludge solids were in the 3,800 to 6,000 mg/1 range. Assuming
equal flow splitting, the primary effluent loading to each tank was
approximately 8 mgd at this time. The average annual primary effluent
BOD concentration was 125 mg/1 according to plant records. Assuming
this waste concentration prevailed, the BOD loading was about 35 pounds/
day/100 pounds MLSS.
5. Extensive Plant Analyses
Plant performance was surveyed on April 25, 1967. Two of the
aeration tanks were monitored. Samples were collected at 7:00 a.m. and
12:30 p.m. to determine performance under the conditions of low and
high flow, respectively. Samples were analyzed for soluble and total
phosphate, total organic carbon (TOC), and TSS. Results are listed
in Table 3. The plant was not removing phosphate during this survey.
The MLSS concentration in the aeration tanks tested was
approximately 2,500 to 2,700 mg/1. This range is over 1,000 mg/1
higher than the concentrations measured on April 18, 1967. Plant
operating personnel were increasing solids in these tanks to increase
BOD removal.
Aeration Jug Studies
A series of experiments based on results from the San Antonio
and earlier amenability studies were devised to test the sewage and
sludge of selected plants with regard to orthophosphate removal.
Factors shown to affect the rate and magnitude of orthophosphate
removal are: suspended solids, BOD, and orthophosphate concentration;
metal precipitants; and sludge condition. The results from these
experiments serve as a guide to the disposition of plants tested
with regard to utilization for process demonstration.
1. MLSS Variation
On April 20 and 21, 1967, two sets of six jugs each were
prepared and aerated to determine the effect of suspended solids on
phosphate removal. MLSS concentration ranged from 490 to 4,200 mg/1.
Jug components are recorded in Table 4 and the results in Table 5.
Normally, the aeration period for such jug studies was six
hours. The low solids experiment was terminated at 4.5 hours since
significant phosphate removal had ceased at that time. The high
solids experiment was terminated at 3.5 hours due to failure of the
monitoring equipment.
-------
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18
Table 4
I/
Suspended Solids Variation—Components—'
Low Range Solids, April 20, 1967:
Jug No.
1
2
3
4
5
6
Analytical Test
0-PO as P
TSS 4
TOG
High Range Solids,
2/
PE RS RS (Conc)~
Liters of Component Added
10 1.7 -- 3
10 3.3 -- 1
10 5.0
10 -- 3.35 1
10 -- 4.25 0
__
Concentration (ms/1)
3.8 3.1
3,060 6,120
--
April 21, 1967:
FE ML
.3
. / — —
_
.7
.7
15
3.8
1,960
_
Jug No.
1
2
3
4
5
6
Analytical Test
0-PO, as P
TSS
TOC
3/
PE RS (Conc)-
Liters of Component Added
10 1.5
10 1.8
10 2.1
10 2.4
10 2.8
10 3.0
FE
3.5
3.2
2.9
2.6
2.2
2.0
Concentration (mg/1)
1.8
20,870
30
1.6
--
15.6
_l/Aeration rate for all jugs-17.5 1/min.
_2/Sludge concentrated by settling and decanting.
^/Sludge concentrated by dissolved air flotation.
-------
Table 5
Suspended Solida Variation—Results
(mg/D
Low Solids. April 20. 1967:
19
Jug No.
Aeration
Time-Hrs.
0 (4:00 pm)
1
1.5
2.5
4.5
% 0-PO, Removed
4
Analytical Test
MLSS
TOG initial
High Solids, April
Aeration
Time-Hrs.
0 (1:30 pm)
3.5
7, 0-PO, Removed
4
Analytical Test
1
3.0
3.2
1.9
2.0
1.9
36.7
486
41.0
21?
1
1.5
0.8
46.7
2
3.1
2.9
2.1
2.2
2.0
35.5
500
30.6
1967:
2
2.4
0.8
66.7
3 4
0-PO, -P
T
2.7 3.0
2.7 2.5
1.9 1.9
2.0 1.9
1.8 1.8
33.3 40.0
Concentration
1,042 977
25.5 27.0
Jug No.
3 4
0-PO, -P
*•*
1.5 2.2
0.7 0.8
53.3 63.6
Concentration
5
2.7
2.1
1.9
1.9
1.8
33.3
1,289
24.0
5
1.6
0.6
62.5
6
3.0
3.0
2.3
2.3
2.3
23.3
1,642
25.9
6
1.5
0.5
66.7
MLSS 2,196 2,400 2,744 3,216 3,816 4,204
TOG initial 21.0 17.4 19.0 21.3 14.8 20.2
-------
20
Jug No. 6 of the low solids experiment was composed of mixed
liquor from the head of an aeration tank. It served as a control for
comparing removal efficiency of plant mixed liquor with jug synthetic
mixed liquor. The removal efficiency of this jug was about 10 percent
lower than the other jugs.
Figure 6 is a plot of percent orthophosphate removed versus
mixed liquor suspended solids concentration. The distribution of
results is somewhat scattered, due to the inconsistent initial ortho-
phosphate concentrations. The distribution does show removal to
increase with increasing suspended solids concentration. Therefore,
a MLSS range of 4,000 to 4,500 mg/1 was chosen for subsequent studies.
Plant personnel felt that at least one battery of aeration tanks could
be operated at this level for an extended period of time.
2. BOD Variation
A set of jugs was prepared on April 24, 1967, to determine
the effect of variation in primary effluent BOD concentration on
phosphate removal.
Table 6 shows the components of the aeration jugs and the
results of analytical tests of such components. The BOD of the primary
and final effluents were assumed to be equivalent to the annual averages
obtained from plant records, i.e., 125 and 25 mg/1, respectively. Final
effluent was added to Jugs Nos. 1 and 2 to dilute the primary effluent
concentration to 30 and 60 mg/1, respectively. The BOD in Jug No. 3
was not altered. Jugs Nos. 4, 5, and 6 were supplemented with Metrecal
to produce estimated BOD concentration of 190, 250, and 375 mg/1,
respectively. The mixture of return sludge and primary effluent was
proportioned to produce a MLSS concentration of 4,000 to 4,500 mg/1.
This study was repeated on April 25. The results are shown
in Table 7. The first study on April 24 was not considered acceptable
due to an error in jug makeup which resulted in jug MLSS concentrations
of 7,000 to 8,500 mg/1 rather than the desired 4,000 to 4,500 mg/1.
Mixed liquor suspended solids concentration in the second set of jugs
was in the range 3,500 to 4,500 mg/1.
The data show a 20 percent increase in removal as BOD increased.
The increase, however, is of minor significance due to the small reduction
in phosphate concentration. Subsequent experiments were run using primary
effluent as the nutrient source without benefit of Metrecal supplement.
Soluble total organic carbon concentration of the contents of
each jug was determined before and after addition of return sludge for the
study with the lower suspended solids content and after solids addition for
-------
21
70-
5°
o
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0 30
40
f
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o-Low Solids Run
v -High Solids Run
1000 2000 3000 4000 5000
MIXED LIQUOR SUSPENDED SOLIDS (mg/l)
FIGURE 6 - ORTHOPHOSPHATE REMOVAL VS MLSS
-------
22
Table 6
I/
BOD Variation—Components—
High Suspended Solids, April 24, 1967;
Jug No.-'
1
2
3
4
5
6
Analytical Test
0-PO, as P
TOG
Est. PE
BOD mg/1
30
60
125
190
250
375
PE
Liters
0.8
4.5
10
10
10
10
11
RS (Conc)-
of Component
4.5
4.5
4.5
4.5
4.5
4.5
FE
Added
9.7
6.0
0.5
0.5
0.5
0.5
Concentration (mg/1)
Low Suspended Solids, April
3/
Jug No.-'
1 v
2
3
4
5
6
Analytical Test
Est. PE
BOD mg/1
30
60
125
190
250
375
2.5
71.0
25, 1967:
PE
Liters
* •»
3.3
10.0
10.0
10.0
10.0
_ _
--
2/
RS (Cone)—
of Component
2.0
2.0
2.0
2.0
2.0
2.0
1.2
17.5
FE
Added
13.0
9.7
3.0
3.0
3.0
3.0
Concentration (mg/1)
TSS
TOG
29,320
61-75
24
I/Aeration rate for all jugs-17.5 1/min.
7/Concentrated by air flotation (25,700 mg/1).
2/2.6, 5.2, and 10.4 ml of Metrecal added to Jugs No. 4, 5, and 6,
respectively. Metrecal contains 1.1 mg/ml 0-PO, as Phosphorus
and 290 mg/ml of BOD.
-------
Table 7
23
BOD Variation—Results
(mg/D
High Suspended Solids. April 24, 1967;
Aeration
Time-Hrs .
0 (3:00 p.m.)
2
3
4
'5
6
% Removed
ML Settled (45 min.)
Analytical Test
MLSS
TOC-Initial
Low Suspended Solids,
Aeration
Time-Hrs .
0 (3:00 p.m.)
1
2
3
4
5
6
Z Removed @ 5 hrs.
ML Settled (30 min.)
Item
Mixed Liquor
PE + Metrecal
Filtered ML
Settled Supernatant
1
1.6
1.5
1.5
1.5
1.6
1.7
—
1.7
8,431
24.5
April 25
1
2.3
1.9
1.9
1.8
1.8
1.8
2.1
21.7
2.1
3,724
12.0
24.5
22.0
2
2.3
1.9
1.7
1.7
1.8
1.9
26.1
1.9
7,518
34.0
, 1967:
2
2.4
2.1
1.9
1.8
1.9
1.8
2.0
25.0
2.0
3,554
33.5
22.5
23.0
Jug No .
3 4
0-PO^-P
2.6 3.1
2.5 2.4
2.1 2.0
2.1 2.1
2.2 2.1
2.3 2.2
19.2 35.5
2.4 2.3
Concentration
7,785 7,837
33.5 34.5
Jug No.
3 4
0-P04-P
2.3 2.6
2.1 2.0
1.8 1.8
1.7 1.8
1.8 1.8
1.8 1.8
2.0 2.0
21.7 30.8
1.9 1.9
TSS
3,572 3,540
TOC
72.0 87.0
31.0 35.5
17.5 50.5
5
3.1
2.5
2.0
2.1
2.1
2.2
35.5
2.3
7,770
44.0
5
2.7
2.3
1.9
1.8
1.8
1.7
1.8
37.0
1.8
3,944
107.0
50.5
53.5
6
2.9
2.3
1.8
1.9
1.9
2.0
37.9
2.2
6,951
46.0
6
2.7
2.2
1.8
1.7
1.7
1.6
1.6
40.7
1.6
3,672
94.0
54.0
51.0
-------
24
the study with the higher suspended solids content. These "before and
after" data plotted in Figure 7 show an increase in carbon with an increase
in estimated BOD and considerable adsorption of carbonaceous material
by activated sludge solids within 5 minutes after addition of the solids.
3. Soluble Orthophosphate Variation
Five jugs were prepared on April 26, 1967, to determine the
effect of soluble orthophosphate concentration on its removal and rate
of removal. The BOD of the primary effluent was not altered. Jug
components are given in Table 8.
Since orthophosphate concentration of the primary effluent
was consistently low, it was used as the base line for this study.
Jug No. 1 was set up at normal phosphate concentration as a control.
Potassium dihydrogenphosphate was added to Jugs Nos. 2, 3, and 4,
respectively, to produce initial orthophosphate concentrations of
200, 250, and 300 percent of the control. MLSS concentration ranged
from about 3,400 to 4,000 mg/1. An additional jug (Jug No. 5) was
run with the phosphate variation jugs containing mixed liquor from
the influent end of an aeration tank. The orthophosphate content
was increased 2.5 times that of the aeration tank mixed ILquor to
determine its reaction to increased phosphate load and for comparison
with the synthetic mixed liquor Jug No. 3. The results are recorded
in Table 8. The data show percent removal decrease as initial 0-PO,
concentration increases with the same BOD and MLSS concentrations.
The rate and magnitude of phosphate removal, however, does
not seem to be altered by increased initial 0-PO, concentration as
shown by the similarity in removal of Figure 8.
Comparison of Jugs Nos. 3 and 5 show that Jug No. 3 removed
50 percent more phosphate than Jug No. 5. The MLSS in Jug No. 3,
however, was also 50 percent higher than Jug No. 5.
4. Chemical Addition
Three jugs were set up April 27, 1967, to determine the effect
of iron and aluminum salts on soluble orthophosphate removal. The mixed
liquor was prepared using primary effluent and return sludge. Ortho-
phosphate concentration was determined after thorough mixing. Jug No. 1
served as a control. Jugs Nos. 2 and 3 were dosed with 25 mg/1 of ferric
and aluminum ion, respectively. Aluminum sulfate and ferric chloride
were the chemicals used. After chemical addition and thorough mixing,
soluble orthophosphate concentration was immediately determined. MLSS
concentration ranged from 4,000 to 4,300 mg/1.
-------
25
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-------
26
Table 8
I/
Orthohposphate Variation—'
April 26, 1967
Components in Jugs
Jug No.
1
2
3
4
5
Analytical Test
0-P04 as P
TSS
Analytical Results
Aeration
Time-Hrs .
0 (12:30 p.m.)
1
2
3
4
5
6
% Removed
Settled (30 min.)
Analytical Test
PE
Liters
10
10
10
10
—
2/
RS-' FE
of Component Added
2.0 3.0
2.0 3.0
2.0 3.0
2.0 3.0
— —
ML
__
—
—
—
15
K2H P04-P
mg/1 Added
__
3.0
4.5
6.0
4.5
Concentration (mg/1)
2.1
29
1
2.1
1.5
1.4
1.3
1.1
1.3
1.3
38.0
1.4
2.2
,060
Jug No.
2 3
0-PO/.-P
4.4 5.8
3.7 4.8
3.5 4.5
3.3 4.3
3.2 4.2
3.1 4.2
3.2 4.2
27.3 27.6
4.6 4.4
Concentration
__
— —
4
6.4
6.2
5.8
5.6
5.5
5.4
5.2
18.7
3.5
(mg/1)
5
5.5
5.2
4.9
4.8
4.6
4.6
4.5
18.2
4.7
TSS
3,978 3,696 3,389 3,702
2,264
I/Aeration rate for all jugs - 17.5 1/min.
^/Concentrated by dissolved air flotation.
-------
27
Q_
0>
UJ
I 3
V)
o
i
a.
O
No. 4 (300 % P04 )
No. 5-Plant ML + 250% P04
No. 3 (250%P04)
No. 2 (200% P04)
No. I (100% P04)
3 4
TIME (Mrs.)
FIGURE 8- PHOSPHATE VARIATION - AERATION JUGS
-------
28
The jug components and results are recorded in Table 9 and
the results shown graphically in Figure 9. Addition of iron and
aluminum resulted in immediate orthophosphate removal.
Aluminum produced the most dramatic effect in that all meas-
urable soluble orthophosphate was removed. Seven mg/1 soluble ortho-
phosphate was added to Jug No. 2 after 1.5 hours' aeration and again
after 2.5 hours' aeration. Orthophosphate analysis of phosphate
showed an immediate drop to 3.7 mg/1 after the first addition and a
further decrease to 1.8 mg/1 in 30 minutes. Orthophosphate concen-
tration decreased to 6.1 mg/1 in 30 minutes after the second addition
and 4.7 mg/1 after six hours' total aeration time. During this period,
11.6 mg/1 was removed from a total of 16.3 mg/1.
The jug containing iron removed 70 percent immediately and
87 percent within one hour of aeration time after which no further
reduction was noted. The aluminum and iron salts were effective
reagents for orthophosphate removal; the aluminum salt was more
effective.
No appreciable soluble orthophosphate removal occurred in
the control jug.
5. Aeration Tank Simulation
A jug was set up on April 27, 1967, to simulate treatment in
the aeration tanks using mixed liquor from an aeration tank having one
of the higher aeration rates. Samples were taken from the jug and from
the influent, 1/4 point, 1/2 point, 3/4 point, and effluent of the
aeration tank. Sample collection time was staggered according to the
aeration tank modal detention times as determined from previous dye
studies in order to follow a "slug" of primary effluent through the
tank. Dissolved oxygen concentrations were measured at the one-eighth
points of the aeration tank. Jug settled supernatant and final effluent
were sampled to determine if soluble orthophosphate was released during
final settling. Conditions and results are listed in Table 10.
Figure 10 is a plot of orthophosphate and dissolved oxygen
concentration versus aeration time. Both the aeration tank and jug
removed about 30 percent of the orthophosphate. The jug closely
simulated the aeration tank during this study.
6. Sludge Acclimation
A jug was set up at 6:30 p.m. on April 25, 1967, to acclimate
the return sludge to a high level of orthophosphate removal. Jug
components consisted of 10 liters of return sludge and 5 liters of
primary effluent. A Metrecal solution was continuously fed to simulate
-------
Table 9
29
I/
Chemical Addition"
April 27, 1967
Components in Jugs
Jug No.
1
2
3
Analytical Test
PE
Liters
10
10
10
K&
FE
of Component Added
2.4
2.4
2.4
2.6
2.6
2.6
Fe+3 Al+3
mg/1 Added
25
25
Concentration (mg/1)
0-PO^ as P
TSS
Analytical Results
2.6
1.9
26,260
Aeration
Time-Hrs.
-0.1 (12:00
0 I/
1
1.5
2
3
4
5
6
Analytical Test
1
4/
N)- 2.1
--
1.8
--
1.8
1.8
1.9
2.0
2.0
Jug No.
2
0-PO, (me/l-P)
T
2.3
0.0
0.1
3.7—'
1.8-1 y
6.1-
5.6
4.9
4.7
Concentration (mg/1)
3
2.3
0.7
0.3
--
0.3
0.3
0.3
0.3
0.3
TSS
4,304
3,976
4,096
^I/Aeration rate for all jugs-17.5 1/min.
^/Concentrated by air flotation.
_3/Seven mg/1 0-PO, as P added before sampling.
^/Before chemical addition.
5/After chemical addition.
-------
No. 2 (Aluminum)
-0.1
TIME (Hrs.)
FIGURE 9- CHEMICAL ADDITION - AERATION JUGS
-------
31
Table 10
Aeration Tank-Jug Simulation
April 27, 1967
0-P04. (mg/l-P)
Sampling Time of ,,
Point Sampling Jug— | Aeration
AT, Head, & Jug ML 1:30 p.m. 2.6 2.7
AT, 1/4 pt., & Jug ML 2:15 p.m. 2.1 2.3
AT, 1/2 pt., & Jug ML 3:00 p.m. 1.9 2.1
AT, 3/4 pt., & Jug ML 4:15 p.m. 1.8 2.1
AT, Tail, & Jug ML 5:00 p.m. 1.8 1.9
Jug Effl. (10-min. settling) 5:10 p.m. 1.8
Jug Effl. (60-min settling) 6:00 p.m. 2.0
FE (Clarifiers No. 9-12) 5:45 p.m. — 2.0
FE (Clarifiers No. 9-12) 6:00 p.m. -- 1.9
FE (Clarifiers No. 9-12) 6:15 p.m. -- 1.9
_l/Jug makeup was 15 liters of mixed liquor taken from the head of
Aeration Tank No. 10. MLSS Concentration = 2,368 mg/1.
Jug aeration rate-17.5 liters/rain.
2/MLSS concentration » 2,296 mg/1.
-------
32
c
33
m
m
o
z
QO
c_
C
O
o
o
ORTHOPHOSPHATE (mg/!-P)
_.£
"•D
ft
m
OJ
-£
•a
OJ
ro
/
o
ro
OJ
DISSOLVED OXYGEN (mg/l)
-------
33
a unit BOD loading varying from 0.2 to 0.8 lb./day/lb. of MLSS.
Metrecal contains 290 mg/ml of BOD and 1.1 mg/ml of 0-PO, as P.
Additional soluble orthophosphate was periodically added to the
system to maintain a favorable environment.
The acclimated jug was dosed with phosphate and Metrecal
and aerated overnight at a rate of 17.5 liters/minute, on three
successive occasions. The total amount of soluble orthophosphate
added ranged from 13 to 18 mg/1. Phosphate removal varied from 53
to 67 percent.
Between periods of overnight feeding, the acclimation jug
was monitored concurrently with the orthophosphate variation and
chemical addition experiments. At the beginning of these experiments,
the acclimation jug was decanted and replenished with primary effluent
as described. Neither Metrecal nor supplemental phosphate was added
during these monitoring periods. Thus, the acclimated sludge was
exposed to the same environment as the "control" jugs of these
experiments.
The analytical results are shown in Table 11. On April 26,
the phosphate removal was 55 percent in the acclimation jug and 38
percent in the control. The MLSS concentration of the acclimation
jug was 30 percent higher than the control. On April 27, the accli-
mation jug removed 44 percent, whereas, the control jug removed
5 percent. The MLSS concentration of the acclimation jug was
13 percent higher than the control on this date.
These data show increased removal as a result of the
acclimation procedures applied.
Sewage Characterization
Characterization of samples from the various unit processes of
activated sludge plants and an aeration jug with regard to selected
chemical parameters were included in the investigation. Samples
were taken from a jug study whose conditions and constituents were
those which resulted in maximum phosphate removal. The investigations
were undertaken to determine trends or correlations between parameters
which would be useful in defining the phosphate removal process.
Frequently, phosphate removal from jug aeration was higher than
that in the aeration tanks. During such instances, the probability
of identifying significant differences was greatly enhanced by
characterizing the components in the jug.
The samples were analyzed with and without suspended solids to
differentiate between the quantity of each respective chemical
parameter associated with the solids and that associated with the
-------
34
Table 11
I/
Acclimation-Control Comparison-
April 26-28, 1967
0-PO, as P (mg/1)
Aeration
Time
(Hours)
0
1
2
3
4
5
6
% Removal
MLSS (mg/1)
4/26/67
Acclimation Control,
Jug Jug^'
3.6 2.1
1.5
1.4
2.2 1.3
1.9 1.1
1.7 1.3
1.6 1.3
55.5 38.0
5,162 3.978
4/27/67
Acclimated Control,
Jug Jug—
3.9
2.8
2.6
2.4
1.9
2.2
2.2
43.6
4.872 4,
2.1
1.8
-1.8
1.8
1.9
2.0 .
2.0
4.8
304
4/28/67
Acclimated
Jug
4.1
3.0
2.7
3.1
—
—
—
24.4
—
\J Aeration Rate =17.5 1/min.
"if Jug Components Listed as Jug No. 1, Table No. 8.
3_/ Jug Components Listed as Jug No. 1, Table No. 9.
-------
35
liquid. Separation was accomplished by first decanting, then
centrifuging the resulting supernatant for further solids removal.
Samples resulting from such treatment are referred to as centrates
of the original sample.
The samples characterized and the results will not
be considered in this report since the basic purpose was for
comparison with similar data from other plant studies. The data
and comparisons thereof are reported under separate cover.3
Microbiological Studies
The microbiological studies conducted at the plants tested for
amenability to phosphate removal were divided into two phases.
Phase I consisted of determining bacterial number by the total plate
count method upon analysis of various plant and aeration jug samples.
A correlation was sought relating phosphate removal with bacterial
population. Phase II consisted of selection of predominant colonial
types, transfer to agar slants, and transport to the Ada laboratory
for identification. The final portion of this phase is under way.
The results for the Cleveland and all other amenability studies are
reported under separate cover.1*
The data from the plate count determinations are recorded in
Appendix IV. There is no apparent relationship between suspended
solids concentration and bacterial population. The bacterial counts
remain essentially constant through the aeration tanks and during
the course of the jug runs. Addition of ferric iron and aluminum
salts tended to reduce the count but not significantly. No apparent
change in count was noted during the course of the acclimation
studies.
After comparison of these data, it was concluded that bacterial
counts and phosphate removal, if related, was not detectable by the
methods employed.
3Lively, L. D. et al., "Phosphate Removal by Activated Sludge, Waste
Characterizations," USDI, FWPCA, Robert S. Kerr Water Research Center,
Ada, Oklahoma. 1968.
''Mover, J. E. et al., "Survey of Activated Sludge Treatment Plants
for Predominant Bacterial Types," USDI, FWPCA, Robert S. Kerr Water
Research Center, Ada, Oklahoma. 1968.
-------
36
SUMMARY
Studies conducted at the activated sludge plant (Easterly
Pollution Control Center) in Cleveland, Ohio, April 18-27, 1967,
indicated 25 percent orthophosphate removal.
The aeration tanks are two-pass with a length-width ratio of
25:1. Dye tracer studies show that the tank effluent has a dispersion
index (tgo/t^Q) of 3.0 and a modal detention time equal to 82 percent
of the displacement time. Ten percent of the mixed liquor receives
less than 2 hours of aeration and 30 percent less than 3 hours.
Dye tracer studies of the circular final clarifiers indicated
that the overflow has a modal detention time equal to one-half the
displacement time, and that 25 percent of the return sludge consisted
of short-circuited mixed liquor.
The plant mixed liquor suspended solids concentration varied from
1,500 mg/1 to 2,500 mg/1. The return sludge averaged 27 to 30 percent
of the primary effluent flow. About 400,000 gaL/day of concentrated
activated sludge was wasted.
The amount of air supplied ranged frpm 0.75 to 1.0 cubic feet
per gallon of waste treated which resulted in a dissolved oxygen
concentration of 2 to 5 mg/1 at the 3/4 point in the aeration tank.
Due to reduced air supply throughout the last one-quarter of the tank,
the aeration tank effluent contained 1.5 to 2.5 mg/1 of dissolved
oxygen. The dissolved oxygen in the final clarifiers was normally
3 to 3.5 mg/1. On several occasions, the effluent from the clarifiers
was turbid. During such periods, the dissolved oxygen concentrations
in the final clarifiers ranged from 0 to 0.2 mg/1.
Plant records show that phosphate (mg/l-P) in waste streams during
April 1966, was as follows:
Ortho Total Avg. Ortho/Total
Source Min Max Min Max
Raw Waste 1.2 3.5 5.0 9.5 0.29
Primary Effluent 1.2 4.0 3.3 8.7 0.34
Final Effluent 1.0 3.6 0.9 6.8 0.50
-------
37
Pilot studies were conducted in aerated jugs to determine the
effect on orthophosphate removal resulting from (1) variation in MLSS,
BOD, and 0-PO, concentration; (2) addition of ferric iron and triva-
lent aluminum; and (3) sludge acclimation.
Removal increased from 36 to 67 percent as the MLSS concentration
was increased from 500 to 4,200 mg/1. The MLSS concentrations ranged
from 3,500 to 4,000 mg/1 in the remaining studies. Variation in
primary effluent BOD concentration resulted in removals varying from
22 percent at 30 mg/1 to 41 percent at 375 mg/1. These limited
removals usually occurred in less than three hours of aeration.
Increasing orthophosphate from 100 to 300 percent of the primary
effluent concentration decreased removal from 38 to 19 percent.
Addition of 25 mg/1 of metal ion resulted in removals of
88 percent with iron salts and near 100 percent with aluminum salts.
After acclimating the return sludge for a period of 18 to 42 hours,
orthophosphate removal ranged from 44 to 55 percent in the test jug,
whereas controls removed 5 to 38 percent.
-------
38
CONCLUSIONS
Plant Studies
1. During these investigations, the activated sludge facilities
at the Easterly Pollution Control Center were not removing a significant
quantity of soluble orthophosphate.
2. In the primary effluent, the BOD concentration was about 60
percent, and the soluble phosphate concentration was less than one-half
that prevalent in the San Antonio wastes.
3. The aeration tanks exhibit a degree of longitudinal mixing
and plug flow comparable to the San Antonio Rilling Plant aeration
tanks. Short circuiting of liquid through the aeration tanks is
limited, and sufficient aeration time is provided for significant
soluble phosphate removal.
4. The Cleveland aeration tanks exhibit a greater degree of
longitudinal mixing and less plug-flow characteristics than other
aeration tanks having comparable length-to-width ratios. Based on
previous studies in Mansfield, Ohio, the transverse aeration in the
Cleveland tanks may be the cause of the increased mixing.
5. Conditions normally found in the final clarifiers indicated
rapid solids-liquid separation. Dissolved oxygen levels were judged
adequate to minimize phosphate release. The flow-through character-
istics are indicative of satisfactory clarification performance.
6. Occasionally, conditions found in the final clarifiers
indicated inadequate solids-liquid separation. During such occur-
rences, the low dissolved oxygen levels would be favorable for
phosphate release.
7. The flow-through characteristics of the return sludge system
indicate that a significant amount of mixed liquor short-circuits
directly to the return sludge outlet. This phenomenon is indicative
of little sludge accumulation in the final clarifier and is similar
to that observed in the San Antonio Rilling Plant.
Jug Studies
1. Orthophosphate removal increased with increasing MLSS
concentration.
-------
39
2. At constant MLSS concentration, orthophosphate removal
increased slightly with additional BOD.
3. At constant suspended solids and BOD concentrations, ortho-
phosphate removal decreased slightly with increased initial ortho-
phosphate concentration.
4. Ferric iron and aluminum ion are effective agents for
orthophosphate removal. Aluminum was more effective than iron.
5. Bacterial plate count does not correlate with orthophosphate
removal.
6. Return sludge subjected to a period of acclimation removed
significantly greater quantities of orthophosphate.
7. Based on the results of aeration jug studies, it is concluded
that the amenability of the sludge to phosphate removal is "probable"
when compared with the following scale:
Questionable - 0 to 25% removal
Probable - 25 to 75% removal
Conclusive - 75 to 100% removal
-------
40
RECOMMENDATIONS
1. The Easterly Pollution Control Center at Cleveland, Ohio, is
not recommended for demonstration of biological phosphate removal by
activated sludge unless subsequent investigations indicate that the
waste and sludge are definitely amenable.
2. The following additional investigations and periods of trial
operation should be undertaken to more adequately determine the waste's
amenability to orthophosphate removal:
a. Determine the effect of cutting off the air supply to
the transverse aeration plates in one of the aeration tanks.
b. Test the primary effluent to more adequately determine
the diurnal variation in ortho and total phosphate concentrations.
c. Optimize operating parameters considered essential for
phosphate removal and operate a four-tank battery under such conditions
until it adapts to the modified environment. The results of amenability
studies indicate that the following operational changes should be tried:
(1) Increase MLSS concentration to a maximum practical
level (4,000 mg/1).
(2) Equalize aeration rate through aeration tanks.
(3) Reduce the primary effluent inflow when additional
aeration time is required.
(4) Increase the BOD concentration of the primary
effluent by removing a portion of the primary
clarifiers from service and increase aeration
rate.
3. If a significant amount of phosphate removal is experienced
during the periods of trial operation, the Easterly Pollution Control
Center, because of its flexibility in design and operation, would be
most desirable as a demonstration site.
-------
41
APPENDIXES
Appendix I
Analytical Procedures
by
B. L. DePrater
Sample Preparation
Samples collected for analyses in the field were processed as
outlined in the following analytical procedures.
Samples returned to the Robert S. Kerr Water Research Center
are referred to as whole, centrate, whole fixed, and centrate fixed.
The following table lists the treatment each type received
prior to shipment to Ada.
Sample Treatment
1. Whole None
2. Whole Fixed One (1) ml cone, sulfuric acid per
liter of sample.
3. Centrate The sample was passed through a
Sharpies motor driven laboratory
model continuous centrifuge,
equipped with a clarifier bowl
driven at 23,000 rpm. The sample
was delivered to the centrifuge by
a peristaltic pump at a feed rate
of 150 ml/min. The bowl was
cleaned and rinsed with distilled
water after each sample.
4. Centrate Fixed The centrate sample plus 1 ml/1
cone, sulfuric acid.
All samples were shipped in either 250 or 1,000 ml polyethylene
containers.
-------
42
Chemical Tests
1. Orthophosphate
In the field, initial samples for orthophosphate were filtered
immediately using Schleicher and Schuell No. 588 paper. Subsequent
analysis by the stannous chloride procedure in Standard Methods1
included the use of a B&L Spectronic 20 at 690 mu.
A continuous automatic sampling device, built specifically
to support jug-study phosphate analyses, supplied whole samples to a
Technicon AutoAnalyzer platformed according to the method by Gales
and Julian.2 The manifold and reagents were modified, however, to
more closely approximate Standard Methods.1 The arrangement, in
order of sequence, was as follows:
a. A six-port peristaltic pump circulating jug mixed liquor
continuously.
b. An open-shut solenoid valve system selectively sampling
the flow from a T-connection in each circulating jug line.
c. A stepping relay alternately activating one of six jug
sample solenoids or the solenoid to a distilled wash water supply.
d. A master timer regulating the stepping relay at two-
minute intervals.
e. A Technicon proportioning pump providing the flow of
samples and distilled water to a Technicon continuous filter. This
pump also diluted filtered samples with distilled water in the ratio
of 1:40, respectively.
Whole plant samples were run on the Technicon AutoAnalyzer
using a Technicon Sampler II and a continuous filter with samples
reaching the filter within 30 minutes. No significant orthophosphate
bleedback occurred in unfiltered samples during this period.
Standard Methods for the Examination of Water and Wastewater, 12th
Edition (Method B), p. 234-236. 1965.
2M. E. Gales, Jr., and E. C. Julian, "Determination of Inorganic
Phosphate or Total Phosphate in Water by Automatic Analysis."
Presented at the 1966 Technicon Symposium on Automation in
Analytical Chemistry.
-------
43
2. Total Phosphate
Analyses were conducted on fixed whole samples at the Ada
laboratory within 15 days of sample collection. Initially whole
samples were blended for three to five minutes in a Waring blendor
and then analyzed by the persulfate procedure of Gales and Julian.2
The procedure was modified to more closely approximate th£ Standard
Methods1 procedure for orthophosphate in that the samples were
neutralized after digestion. Also the manifold design and reagents
for the AutoAnalyzer were adjusted to deliver approximately the
amount of reagents per sample outlined by Standard Methods.1
3. Total Carbon and Total Nonvolatile Organic Carbon1
Whole samples were run in the field using the methods of
Van Hall, Safranko, and Stenger and Van Hall, Earth, and Stenger.
A Beckman Carbonaceous Analyzer was used. Preliminary homogenization
in a Waring blendor provided representative syringe sampling of whole
samples. As the whole acidified sample was further purged with
nitrogen gas for five minutes, results were reported as total
nonvolatile organic carbon. Acetic acid standards were used for
instrument calibration.
Physical Tests
1. Solids
Tests for total suspended and total volatile suspended solids
were conducted according to Standard Methods.5 Reeve Angel 2.4-cm
glass fiber filters grade 934AH were used in lieu of asbestos mats.
Gooch crucibles were fired at 600°C, cooled, the mats placed in the
crucibles and dried at 103°C for at least 1 hour before initial weighing.
At intervals, crucibles with filters were subjected to 600°C furnace
temperatures to check for weight loss due to the filter. Total and
total volatile solids were determined according to Standard Methods.6
3Analytical Chemistry, 35:3, p. 315-319. 1963.
^C. E. Van Hall, D. Earth, and V. A. Stenger, "Elimination of
Carbonates from Aqueous Solutions Prior to Organic Carbon
Determination," Anal. Chem. 37:6, 769. 1965.
5Standard Methods for the Examination of Water and Wastewater, 12th
Edition (Methods C & D), p. 424-425. 1965.
6Standard Methods for the Examination of Water and Wastewater, 12th
Edition (Methods A & B), p. 423-424. 1965.
-------
44
2. Dissolved Oxygen
Measurements were made in situ with a YSI Model 51 Oxygen
Meter equipped with a Model 5103 oxygen/temperature probe. The meter
was calibrated against the AzJde Modification of the Winkler Method
described in Standard Methods.7 The meter was also calibrated against
saturated air at the temperature of the test medium.
3. Hydrogen Ion Concentration
All pH measurements were made using a line current Beckman
Zeromatic II equipped with glass and calomel electrodes. Measure-
ments were made on whole-untreated samples.
4. Temperature
Temperature measurements were made with a battery powered
thermistor-thermometer.
NOTE: Mention of products and manufacturer is for
identification only and does not imply endorse-
ment by the Federal Water Pollution Control
Administration or the U. S. Department of the
Interior.
7Standard Methods for the Examination of Water and Wastewater, 12th
Edition (Method A), p. 406-410. 1965.
-------
45
Appendix II
Easterly Pollution Control Center
Cleveland, Ohio
PHOSPHATE MONITORING
Date
Total Phosphate
Raw
Sett
Eff
Dissolved Phosphate
PO, - ppm
Raw Sett Eff
4/3/66
4/4/66
4/5/66
4/6/66
4/7/66
4/10/66
4/11/66
4/12/66
4/13/66
4/14/66
4/17/66
4/18/66
4/19/66
4/20/66
4/21/66
4/24/66
4/25/66
4/26/66
4/27/66
4/28/66
Max.
Min.
Avg.
% Reduction
5/1/66
5/2/66
5/3/66
5/4/66
5/5/66
5/8/66
5/9/66
5/10/66
5/11/66
19.2
22.0
25.2
18.4
18.4
20.8
22.0
28.4
24.0
23.2
25.0
15.0
18.7
19.0
15.0
16.3
15.0
28.4
15.0
20.3
16.0
13.4
15.7
13.4
9.1
9.1
14.8
19.2
24.8
18.4
19.6
19.6
22.0
19.2
26.0
21.0
21.6
18.7
16.1
17.3
14.7
12.7
17.4
10.0
13.4
26.0
10.0
18.4
9.4
14.4
12.0
13.5
11.7
9.1
8.0
11.4
10.4
16.0
16.8
10.4
16.0
11.2
14.0
20.4
13.2
17.6
17.3
14.0
12.0
2.7
9.0
10.7
8.0
6.7
20.4
2.7
12.6
37.9
12.4
8.0
9.4
11.4
8.1
8.7
11.4
4.0
10.6
8.0
7.0
5.4
9.2
4.4
9.2
7.8
10.2
8.8
8.7
13.7.
3.8
3.5
4.3
3.8
13.7
3.5
7.0
9.0
5.8
4.2
3.8
5.4
7.5
6.7
5.2
3.7
5.4
7.4
8.2
7.2
6.6
9.8
5.2
9.2
7.8
9.8
10.8
8.7
12.0
5.2
4.7
5.9
3.7
4.7
12.0
3.7
7.4
8.7
3.3
3.0
8.2
5.8
5.0
3.3
5.4
9.0
7.8
7.2
7.4
8.8
5.2
6.8
7.4
8.2
10.8
9.4
10.1
4.9
5.0
6.4
4.7
3.2
10.8
3.2
7.3
8.5
6.7
6.8
4.3
4.3
8.0
4.9
6.0
4.3
-------
46
Appendix II(Cont'd.)
Total Phosphate Dissolved Phosphate
PO, - ppm P04 - ppm
Date Raw Sett Eff Raw Sett Eff
5/12/66
5/15/66
5/16/66
5/17/66
5/18/66
5/19/66
5/22/66
5/23/66
5/24/66
5/25/66
5/26/66
5/30/66
5/31/66
Max.
Min.
Avg.
% Reduction
6/1/66
6/5/66
6/6/66
6/8/66
6/9/66
6/13/66
6/14/66
6/15/66
6/16/66
6/19/66
6/20/66
6/21/66
6/22/66
6/23/66
6/26/66
6/27/66
6/28/66
6/29/66
Max.
Min.
Avg.
% Reduction
15.0
16.4
16.9
18.4
25.4
21.4
25.0
25.4
16.4
25.4
9.1
17.2
15.5
15.3
26.7
14.2
18.2
15.0
15.6
14.2
15.3
17.7
15.3
20.7
23.7
20.0
17.7
19.3
20.0
16.0
26.7
14.2
17.8
13.7
15.4
19.7
13.3
15.5
19.4
16.7
18.7
25.4
24.7
13.7
13.5
25.4
8.0
15.2
11.6
15.3
15.5
19.2
15.5
14.3
13.3
16.3
14.8
15.3
17.0
14.0
18.0
17.0
17.6
15.6
16.0
16.7
16.3
19.2
13.3
16.0
10.1
10.7
15.4
19.4
11.7
9.7
11.7
13.3
16.7
17.7
10.4
12.4
10.1
19.4
8.0
12.1 •
29.7
12.7
14.3
7.4
12.5
11.7
13.5
9.3
10.6
8.0
15.3
12.3
16.0
14.6
14.8
14.7
15.0
15.0
11.6
16.0
7.4
12.7
28.7
3.4
11.1
8.2
14.4
8.3
16.1
10.2
7.0
9.0
16.1
3.4
7.9
6.4
11.0
11.0
8.7
5.5
7.3
5.7
5.7
4.7
12.0
6.2
11.7
9.3
12.0
11.8
11.8
9.3
9.8
12.0
4.7
8.9
3.0
3.0
9.4
7.9
7.0
7.2
12.4
8.3
13.7
8.7.
8.7
12.3
8.0
13.7
3.0
7.3
7.6
7.7
13.0
10.5
8.0
5.5
7.3
5.3
5.0
5.7
13.3
6.3
11.0
10.0
10.5
12.5
10.7
8.0
9.2
13.0
5.0
8.8
1.1
2.7
1.5
10.1
10.1
4.7
5.9
9.4
9.2
12.0
7.7
0.7
12.0
8.4
12.0
0.7
6.7
15.2
7.5
12.0
7.2
6.7
6.7
8.7
2.2
4.7
4.2
6.7
11.0
11.0
11.7
12.7
13.0
8.3
7.7
13.3
2.2
8.5
4.5
-------
Appendix II(Cont'd.)
Date
Total Phosphate
P04 - ppra
Raw Sett Eff
47
Dissolved Phosphate
P04 - ppm
Raw Sett Eff
7/4/66
7/6/66
7/14/66
7/21/66
7/28/66
Max.
Min.
Avg.
% Reduction
8/4/66
8/11/66
8/18/66
8/25/66
8/31/66
Max.
Min.
Avg.
% Reduction
9/8/66
9/15/66
9/22/66
9/28/66
9/29/66
Max.
Min.
Avg.
% Reduction
10/6/66
10/13/66
10/20/66
10/27/66
10/31/66
Max.
Min.
Avg.
% Reduction
17.8
27.3
24.1
25.5
24.2
27.3
17.8
23.8
20.2
26.5
17.4
20.3
21.7
26.5
17.4
21.2
26.1
24.6
37.1
26.7
37.1
24.6
28.6
23.3
34.5
27.3
31.5
24.0
34.5
23.3
28.1
13.7
24.2
22.2
17.9
23.5
24.2
13.7
20.3
14.7
17.3
17.4
16.4
17.4
18.3
18.3
16.4
17.4
17.9
21.2
20.7
26.0
20.7
26.0
20.7
22.1
22.7
15.3
24.0
18.2
23.7
20.0
24.0
15.3
20.2
28.1
12.5
13.5
21.7
12.1
15.5
21.7
12.1
15.0
36.9
9.6
13.0
9.1
11.6
12.0
13.0
9.1
11.0
48.2
15.4
10.1
6.3
10.1
12.4
15.4
6.3
11.1
61.2
12.7
12.0
9.4
14.5
10.1
14.5
9.4
11.7
58.4
14.0
16.6
20.3
12.2
17.8
20.3
12.2
16.2
10.8
4.8
9.7
12.8
12.5
12.8
4.8
10.1
12.5
8.2
12.2
12.5
8.2
11.0
12.3
14.4
12.4
12.2
10.7
14.4
10.7
12.4
11.2
15.7
17.4
11.1
17.8
17.8
11.1
14.6
9.9
8.7
10.6
9.2
10.9
9.2
10.9
8.7
9.7
4.0
10.8
7.7
12.4
12.4
7.7
10.3
3.9
4.1
14.0
11.8
14.4
10.7
14.4
4.1
11.0
11.3
5.8
12.6
17.4
10.6
13.5
17.4
5.8
12.0
25.9
7.5
8.7
6.7
11.1
9.0
11.1
6.7
8.6
14.9
12.1
8.9
8.8
12.1
8.8
9.9
14.9
6.7
9.8
5.7
9.4
8.6
9.8
5.7
8.0
35.5
-------
48
Appendix II(Cont'd.)
Total Phosphate Dissolved Phosphate
PO, - ppm PO, - ppm
Date Raw Sett Eff Raw Sett Eff
11/4/66
11/10/66
11/16/66
11/24/66
11/30/66
Max.
Min.
Avg.
% Reduction
12/8/66
12/15/66
12/21/66
12/29/66
Max.
Min.
Avg.
% Reduction
19.7
15.7
23.3
25.2
20.0
25.2
15.7
20.8
26.6
21.8
22.0
19.5
26.6
19.5
22.5
14.5
12.4
22.8
20.3
18.6
22.8
12.4
17.7
14.9
24.4
17.3
20.0
16.7
24.4
16.7
19.6
12.9
10.2
9.6
14.5
11.4
10.5
14.5
9.6
11.2
46.2
14.2
10.8
12.5
15.5
15.5
10.8
13.3
40.9
11.1
9.4
13.1
13.3
10.9
13.3
9.4
11.6
13.3
11.2
10.2
11.1
13.3
10.2
11.4
8.3
9.9
12.0
12.5
10.9
12.5
8.3
10.7 .
7.7
11.0
10.8
8.8
13.3
13.3
8.8
11.0
3.5
8.2
8.2
7.7
9.6
8.4
9.6
7.7
8.4
27.6
9.2
8.2
7.2
8.1
9.2
7.2
8.1
28.9
-------
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-------
50
Appendix IV
TOTAL PLATE COUNT
Suspended Solids Variation
Low Solids, April 20, 1967:
Jug No.
0 (4:00 pm)
i
1 8.4 x 105
2 TNTC-10"Jdil.
3 2.1 x 10 !?
4 1.4 x 10 !?
5 2.9 x 10^
6 1.9 x 106 i
Aeration Time (Hrs.)
2
j
1.1 x 10^ I
2.1 x 10°
3.5 x 10 |
TNTC-10~fdil. !
TNTC-10" dil. '
TNTC-10" clil.
4
TNTC-10"4dil.
TNTC-10"4dil.
TNTC-10"4dil.
6.9 x 10;?
3.0 x 10^
1.4 x 10 ;
6
5.7 x 105
7.5 x 10^
1.4 x lo£
6.7 x 10
overgrown
overgrown
High Solids, April 21, 1967:
Jug No.
1
2
3
4
5
6
Aeration Time (Hrs.)
0 (1;30 p.m.)
3
1
3
5
1
4
.2
.7
.2
.5
.0
.1
x
x
X
X
X
X
10
10
10
10
10
10
6
6
6
6
6
6
TNTC
2.1
2.2
1.2
7.1
2.9
x
x
X
X
X
at
10
10
10
10
10
1°
6
5
5
6
-5
dil.
-------
BOD Variation
51
High Suspended Solids, April 24, 1967;
Aeration
Time-Mrs.
0 (3:00 pm)
1
2
3
4
5
6
Jug No.
136
Contaminated
Contaminated
4.6 x 10^
2.8 x loi?
2.1 x W
8.2 x W5
7.3 x 105
Contaminated
Contaminated
1.3 x 10£
7.2 x 10;?
9.3 x 10*
2.6 x 10 1
5.2 x 105
Contaminated
Contaminated
2.8 x 10*?
2.9 x 10?
3.9 x 10;
4.5 x 10?
1.4 x 10
Low Suspended Solids, April 25, 1967:
Aeration
Time-Hrs.
0 (3:00
1
2
3
4
5
6
Jug No.
pm) 2
1
2
3
3
6
1
Soluble
1
5
.7 x 10
.4
.0
.1
.2
.3
.7
l
i
j
1
1
3
5
5.0 x 10
2.5
1.9
1.8
5.5
1.1
2.3
3
2
3
2
2
2
2
6
.8 x
.3 x
.3
.2
.5 x
.7 x
.4
,
10
105
6
W5
Orthophosphate Variation
April 26, 1967
Aeration
Time-Hrs.
0 (12:30
2
4
6
pm) 2.3
1.9
4.0
1.0
1
x 105
6
x 10
Jug
3
6.3 x 10
OG at 10
dil.
5.0 x 10
1.0 x 10
No.
4
5
5 TNTC-10"6dil. TNTC-10"
~6 2.0 x 105 3.7
| 1.5 x 10 !| 1.6
3.0 x 10 1.4
x 10
x 10
x 10
?dll
5
6
-------
52
Chemical Addition
April 27, 1967
Jug No.
Aeration
Time-Hrs.
1 (Control) 2(A1+3) 3 (Fe+3)
0 (12:00 N) 6 6 6
Before Chem. Add. 1.2 x 10 1.8 x K>5 2.0 x 105
5-min after chem. add. - 2.9 x 10 2.7 x 10
2 3.7 x 103 4.3 6.6
4 4.4 5.6 7.9
6 2.6 2.9 3.7
Plant Characterization
Aeration Tank ML
Date
4/18/67
5:00 pm
4/26/67
3:00 pm
Date
4/18/67
5:30 pm
4/27/67
12:30 pm
TPC
Tank No. Influent Effluent
1 2.5 x iO* . 6.8 x 10*
3 5.0 x 10* 4.7 x 105
5 7.5 x 101 6.1 x 10
7 5.7 x 105 8.2 x 10*
9 7.6 x 10 3.3 x 105
Return Sludge
Channel No. ; TPC
1 4.0 x 10g
2 1.8 x 106
3 3.0 x 10
4 2.2 x 106
4 7.9 x 105
Primary Effluent
Date TPC
4/18/67 6:00 pm 1.3 x 10^
4/27/67 12:00 N 3.1 x 105
Raw Sewage
Date
TPC
4/25/67 12:30 pm
4/26/67 1:30 pm
1.2 x 10
1.8 x 10
-------
53
Acclimation Study
Time TPC
11:
9:
10:
6:
11:
12:
2:
4:
x
30
00
30
30
50
15
00
00
a
P
a
P
a
P
P
P
.m.
.m.
.m.
.m.
.m.
.m.
.m.
.m.
3.
1.
2.
1.
6.
2.
1.
2.
4
4
0
6
8
7
5
6
j«
x
x
X
X
X
X
X
10
10
10
10
10
10
10
8
6
5
J
6
g
5
5
6:00 p.m. 7.6 x 10"
Tank-Jug Simulation
April 27, 1967
Sample Time TPC
!C =
4:15 p.m. 1.2 x
Jug 2:15 p.m. 5.3 x 10",
AT #10 3/4 pt. 4:15 p.m. 5.2 x 105
Jug Characterization
April 27, 1967
Time TPC
12:00 N 3.1 x 10^
2:00 p.m. 1.4 x 105
4:00 p.m. 2.1 x 105
6:00 p.m. 5.6 x 10
-------
ACKNOWLEDGMENT
Grateful acknowledgment is given to many individuals who
contributed significantly to the success of this study. The
major portion of this work was made possible through the cooper-
ation of the city of Cleveland, Ohio. Particular recognition is
given to Mr. John Wirts, Superintendent of the Easterly Pollution
Control Center, and to Mr. Orthello Skinner, Chief Chemist. Members
of the Robert S. Kerr Water Research Center staff who participated
in the field work were Messrs. B. E. Bledsoe, M. L. Cook, J. F. McNabb,
B. D. Newport, and Dr. J. E. Moyer. Members of the Robert S. Kerr
Water Research Center staff who contributed in other respects were
Messrs. K. F. Jackson, R. L. Cosby, and E. R. Ray.
------- |