TECHNICAL ASSISTANCE PROJECT
AT THE
NORTH AND SOUTH WASTEWATER TREATMENT PLANTS
TITUSVILLE, FLORIDA
March, 1976
it pr
Environmental Protection Agency
Region IV
Surveillance and Analysis Division
Athens, Georgia
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TECHNICAL ASSISTANCE PROJECT
AT THE
NORTH AND SOUTH WASTEWATER TREATMENT PLANTS
TITUSVILLE, FLORIDA
March, 1976
!" • Atactica Ageocy
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Environmental Protection Agency
Region IV
Surveillance and Analysis Division
Athens, Georgia
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TABLE OF CONTENTS
Page
INTRODUCTION 1
SUMMARY 2
RECOMMENDATIONS 3
NORTH WASTEWATER TREATMENT PLANT
TREATMENT FACILITY 4
Treatment Processes 4
Personnel 4
STUDY RESULTS AND OBSERVATIONS 4
Flow 4
Waste Characteristics and Removal Efficiencies 8
Aeration Basin 10
Clarifiers 14
Chlorine Contact Chamber 17
Anaerobic Digesters 17
Laboratory 17
SOUTH WASTEWATER TREATMENT PLANT
TREATMENT FACILITY ' 18
Treatment Processes 18
Personnel 18
STUDY RESULTS AND OBSERVATIONS 18
Flow 18
Waste Characteristics and Removal Efficiencies 22
Aeration Basin 22
Clarifiers 25
Chlorine Contact Chamber 25
Anaerobic Digester 25
Laboratory 25
REFERENCES 29
APPENDICES
A. LABORATORY DATA 30
B. GENERAL STUDY METHODS 34
C. ACTIVATED SLUDGE FORMULAE USED FOR GENERAL CALCULATIONS 36
D. RETURN SLUDGE FLOW - NORTH WTP 38
E. OXYGEN UPTAKE PROCEDURE 39
FIGURES
1. NORTH WASTEWATER TREATMENT PLANT 5
2. PLANT FLOW - NORTH WTP 9
3. SETTLOMETER TEST - NORTH OTP 12
4. EFFECT OF LAUNDRY WASTE ON NORTH WTP MLSS SETTLEABILITY 13
5. CLARIFIER DYE TRACER STUDY - NORTH WTP 16
6. SOUTH WASTEWATER TREATMENT PLANT 19
7. PLANT FLOW - SOUTH WTP 21
8. SETTLOMETER TEST - SOUTH WTP 24
TABLES
I. DESIGN DATA - NORTH WTP 6
II. WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES - NORTH
WTP 8
III. AERATION BASIN OPERATIONAL PARAMETERS - NORTH PLANT 10
IV. OXYGEN UPTAKE RATES - NORTH WTP 14
V. SECONDARY CLARIFIER OPERATIONAL PARAMETERS - NORTH WTP. 15
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TABLE OF CONTENTS
(Cont.)
Page
VI. DESIGN DATA - SOUTH WTP 20
VII. WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES - SOUTH WTP .. 22
VIII. AERATION BASIN OPERATIONAL PARAMETERS - SOUTH PLANT 23
IX. OXYGEN UPTAKE RATES - SOUTH WTP 23
X. SECONDARY CLARIFIER OPERATIONAL PARAMETERS - SOUTH PLANT 25
XI. SPLIT SAMPLE COMPARISON 26
XII. ANALYSIS OF REFERENCE SAMPLES 27
XIII. EPA-TITUSVILLE SETTLEABILITY COMPARISON 28
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INTRODUCTION
A technical assistance study of operation and maintenance problems
at the North and South Wastewater Treatment Plants (WTP) serving Titusville,
Florida was conducted February 29 - March 5, 1976 by the Region IV, Surveil-
lance and Analysis Division, U.S. Environmental Protection Agency. Opera-
tion and maintenance technical assistance studies are designed to assist
wastewater treatment plant operators in maximizing treatment efficiencies
as well as assisting with special operational problems. Municipal waste-
water treatment plants are selected for technical assistance studies after
consultation with state pollution control authorities. Visits are made
to each prospective plant prior to the study to determine if assistance is
desired and if study efforts would be productive.
The North plant was selected because of difficulty in achieving de-
sign treatment efficiencies without the addition of alum and polymer. In
addition, excessive solids were frequently lost in the effluent. Some work
was also performed at the South plant, even though plant performance was
satisfactory. Since the main city laboratory is located at this plant, it
was felt that comparison of laboratory and process control procedures would
be helpful to plant personnel. The specific study objectives for both the
North and South WTP's were to:
© Optimize treatment through control testing and recommended
operation and maintenance modifications,
» Determine influent and effluent wastewater characteristics,
© Assist laboratory personnel with any possible laboratory
procedure problems, and
© Compare design and current loadings,
A follow-up assessment of plant operation and maintenance practices
will be made in June, 1976. This will be accomplished by utilizing data
generated by plant personnel and, if necessary, subsequent visits to the
facility will be made. The follow-up assessment will determine if recom-
mendations were successful in improving plant operations, and if further
assistance is required.
The cooperation of the Florida Department of Environmental Regulation
is gratefully acknowledged. The technical assistance team is especially
appreciative of the cooperation and assistance received from the waste
treatment personnel in Titusville, Florida.
1
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SUMMARY
NORTH WASTEWATER TREATMENT PLANT
The North Wastewater Treatment Plant (WTP) serving Titusville, Florida,
was designed as a 1.5 mgd completely mixed activated sludge system. The WTP
is presently handling an approximate flow of 1.3 mgd. The average BOD^ and
TSS reduction during the study period was 92 and 90 percent, respectively.
Problems with sludge settleability necessitate the use of alum and polymers
by plant personnel in order to meet NPDES permit limits.
The major problems observed during the study were as follows:
e The activated sludge settled extremely rapidly, leaving a cloudy
supernatant. Also, heavy solids carryover from the final clarifier
occurred routinely. Chemical addition is necessary to adequately
remove the suspended solids.
© Bench scale settleability tests indicated that a commercial laundry
facility may be adversely affecting activated sludge settleability.
o Clarifier effluent weirs were not level and were probably a major
cause of hydraulic short-circuiting, especially in the east clari-
fier .
® The east final clarifier is a converted primary clarifier, which
does not have a rapid sludge pick-up and requires a high return ¦
sludge flow rate in order to operate properly. The subsequent
thin sludge in the east clarifier necessitates all sludge wasting
to be from the west clarifier.
e Poor operation of the grit removal system.
SOUTH WASTEWATER TREATMENT PLANT
The South WTP serving Titusville, Florida, was designed as a 2 mgd
completely mixed activated sludge system. The WTP presently handles a
wastewater flow of about 1 mgd with no significant industrial connections.
The average BOD^ and TSS reduction during the study period was 89 and 98
percent, respectively. The activated sludge settled slowly, which when
controlled properly in the final clarifier, results in a clear effluent.
Laboratory analyses for both the North and South WTP's are performed
at the South WTP. The laboratory was well equipped and staffed. Both
during and since completion of the technical assistance study, members of
the 0 & M team have worked with the laboratory concerning quality control.
This has included analyses of split samples1,1 reference samples, and con-
tinued consultation.
An in-plant control testing and analysis program for both plants was
discussed with the WTP personnel. The plant has already begun implementa-
tion of this recommendation.
2
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RECOMMENDATIONS
Based on observations and data collected during the study, it is
recommended that the following measures be taken to improve wastewater
treatment and plant operation:
NORTH WASTEWATER TREATMENT PLANT
1. The commercial laundry wastewater should be hauled to the
South WTP for at least two weeks and the treatment efficiencies
and activated sludge settleability monitored at both the North
and South WTP's.
2. Data generated from recommendation 1 above, combined with results
in this report and a previous study by the City of Titusville,
should be used to formulate the best means of handling the commer-
cial laundry wastewater.
3. Influent waste characteristics and the MLVSS concentration should
be monitored regularly in order to maintain a fairly constant Food
to Microorganism ratio (F/M) at a value which consistently results
in the best MLSS settleability and treatment efficiency. It is
suggested that the MLSS be increased in order to maintain an F/M
ratio of approximately 0.2 - 0.3 with a concurrent increase in the
return sludge flow rate.
4. Consideration should be given to extending the center baffle
downward in the east clarifier.
5. Clarifier weirs should be leveled and/or replaced, if necessary.
6. The east clarifier should be equipped with a satisfactory sludge
pickup system.
7. A decision regarding whether or not an additional clarifier is
needed and/or special handling of the laundry wastewater is re-
quired should be delayed until after completion of the recommen-
dations dealing with the hydraulics of the final clarifiers (rec-
ommendations 4, 5, and 6).
8. An in-plant control testing schedule should be initiated and
trend charts established and maintained.
SOUTH WASTEWATER TREATMENT PLANT
1. Continued quality control work should be performed to resolve
the discrepancies in COD analyses.
2, An in-plant control testing schedule should be initiated and
trend charts established and maintained.
3
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NORTH WASTEWATER TREATMENT PLANT
TREATMENT FACILITY
Treatment Processes
A schematic diagram of the 1.5 mgd North Wastewater Treatment Plant
(WTP) is presented in Figure 1. Design data are enumerated in Table I.
The completely mixed activated sludge WTP began operation in September,
1967 and presently serves an approximate population of 13,000. Roughly
10 percent of the influent plant flow is from industrial sources, primar-
ily a commercial laundry and hospital.
Limited operational flexibility was designed into the plant. The
east clarifier was a primary clarifier prior to the 1967 expansion and
is not equipped with vacuum sludge pick-up capabilities, which requires
a high return sludge flow rate in order to operate properly. The sub-
sequent thin sludge in the east clarifier necessitates all sludge wasting
to be from the west clarifier.
The WTP personnel have been adding alum to increase waste treatment
efficiency since 1973. Presently, 2,500 lbs. of alum and 120 lbs. of a
cationic polymer are added daily to the aeration basin effluent to aid in
settling. The aeration basin was also designed to collect grit in a col-
lection well. The grit is then pumped to a separate grit removal structure.
However, this system has reportedly never worked.
The final effluent is chlorinated and discharged into the Indian River
approximately 200 yards from the plant.
Personnel
The North WTP is staffed by five persons holding the following classi-
fications: 1-A, 1-B, 2-C, and 1-LCO. Maintenance at the North and South
WTP is performed by a separate city maintenance department.
STUDY RESULTS AND OBSERVATIONS
A complete listing of all analytical data and general study methods
are presented in Appendices A and B. Formulae used for general calculations
are enumerated in Appendix C. Significant results and observations made
during the study are discussed in the following sections.
Flow
Plant flow was measured with a venturi meter equipped with a recorder
and totalizer, which was installed in the 24 inch effluent pipe line. A
venturi meter equipped with a recorder and totalizer, installed in a 16 inch
pipe line, was used to measure return sludge flow.
4
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Notes
Design Flow = 1.5 mgd
Avg. Flow (1975) = 1.3 mgd
(§1 - denotes 50.hp aerator
o - denotes sampling locations
FIGURE 1
NORTH WASTEWATER TREATMENT PLANT
TITUSVILLE, FLORIDA
Grit Removal
Structure
Sludge Drying
Beds
No.
1
No.
2
No.
3
No.
4
Sludge
recir-
culation
basin
c+j
•h y
u ci c
0-P *H
1-l C W
.CO a!
OU Q
»NE
Discharge to
Indian River
Comminutor Structure
nfluent Force Main
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TABLE I
DESIGN DATA - NORTH WTP
TITUSVILLE, FLORIDA
FLOW MEASUREMENT
Final Effluent
Return sludge flow
Design flow
Average flow
AERATION BASIN
Venturi meter (24 in.), totalizer
recorder
Venturi meter (16 in.), totalizer
recorder
1.5 mgd
1.32 mgd (1975 monthly average)
1.2 mgd (study period average)
Diameter
Side water depth (SWD)
Center depth
Aeration
Volume
65 it.
14 ft.
17.5 ft.
1-50 hp low speed aerator
46,456 cu. ft. (0.35 m.g.)
CLARIFIERS
Number
Diameter
Side water depth
East
West
Area
Volume
East
West
Weir Length
2
40 ft.
7.0 ft.
7.75 ft.
1,257 sq. ft.
8,800 cu.
9,742 cu.
126 ft.
ft. (.066 m.g.)
ft. (.073 m.g.)
CHLORINE CONTACT CHAMBER
Length 38 ft.
Width 19,2 ft.
Water depth 7.75 ft.
Volume 5^654 cu.
Detention (at design flow) 40 min.
ft. (.042 m.g.)
6
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ANAEROBIC DIGESTERS
Number 2 (Primary and Secondary)
Primary Mixed
Diameter 36 ft.
SWD 21.5 ft.
Cone 10 ft.
Secondary
Diameter
SWD
Cone
Not mixed
50 ft.
22.5 ft.
6 ft.
PUMPS
Return sludge
Waste sludge
Digester recirculation
pump
2 - 1400 gpm variable speed
2 - 200 gpm
350 gpm
7
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Average hourly flows from the plant during February 15-16, 20-21, and
February 29 - March 3, 1976 are presented in Figure 2. Average flow during
the study was 1.2 mgd. The monthly average flow for 1975 was 1.32 mgd, with
a peak flow of 1.5 mgd. Approximately ten percent of the influent wastewater
flow is from industrial sources, of which about 0.05 mgd is from a commercial
laundry.
The average return sludge flow during the study was 0.4 mgd. The typical
return sludge flow pattern is presented in Figure 2 and in Appendix D. The
variable speed return sludge pump is set at about 0.6 mgd from 7.a.m. until
11 p.m. and then operated on a timer the remainder of the day, pumping at a
rate of approximately 1.2 mgd for 15 minutes each hour. Experience of the
operator has shown that cycling the return sludge at night is more effective
than returning at a constant rate.
Each clarifier is equipped with a 200 gpm constant speed waste sludge
pump, although all wasting is from the west clarifier. The waste sludge
pumping schedule is as follows: 40 seconds per hour 16 hours per day, and
40 seconds every two hours from 11 p.m. until 7, a.m.
Waste Characteristics and Removal Efficiencies
Table II presents a chemical description of the influent and effluent
wastewater with calculated percent reductions shown for all parameters. Analyses
were made on 24-hour composite samples, collected on three consecutive days.
TABLE II
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
NORTH WTP
Influent
Effluent
(mg/1)
Parameter
(mg/1)
% Reduction
Doi/
B0D5
COD
TSS
VSS
Total Solids
Total Volatile Solids
Settleable Solids (ml/1)
TKN-N
NH3-N
no3-no2-n
Total Phosphorus
Lead
Chromium
Cadmium
Copper
Zinc
114
683
232
0
251 (200)*
489
123 (164)*
9.2
33.1
25.3
<0.03
9.8
<0.08
<0.11 y
<0.02
0.20
557
78
<0.1
26
21
0.037
1.07
<0.08
<0.08
<0.02
3:5 .
0.02
6
19 (14)*
75
12 (20)*
12
92
85
90
89
18
66
99
21
17
77
90
89
* - () denotes 1975 monthly average
_1/ - Grab sample on March 2, 1976
2/ - The two samples had concentrations of <0.08 and 0.14 mg/1
8
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2.5 r—
2.0
FIGURE 2
PLANT FLOW - NORTH WTP
TITUSVILLE, FLORIDA
>
O
1.5
1.0
0.5
Approx. 30 Win.
Pumping Cycle n
KEY
Plant Flow
Return Sludge Flaw
N S M 6 6 N 6
2/15 2 / IS 2/20
SUNDAY MOMDAY FRIDAY
M 6 8 N 6
2/21 2/29
SATURDAY SUNDAY
6 N 6
3/1
MONDAY
N €
3/2
TUESDAY
N 6
3/3
WEDNESDAY
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The high percent removal of BOD, solids, arid phosphorus was due to the
addition of alum and polymer.
A grab sample of the commercial laundry waste was collected on March 3,
1976. The sample had a "kerosene type" odor, a pH of 10.6, and a temperature
of 100? F.
Aeration Basin
Grab samples were taken from the aeration basin and analyzed for
total suspended solids (TSS), volatile suspended solids (VSS), percent
solids by centrifuge, and settleability as determined by the settleometer.
Presented in Table III are various activated sludge operational parameters
calculated during the study period and the corresponding recommended values
for the completely mixed activated sludge process.
TABLE III
AERATION BASIN OPERATIONAL PARAMETERS - NORTH WTP
Measured Recommended (2)(5)
MLSS (mg/1)
MLVSS (mg/1)
Hydraulic Detention Time (hrs.)
Mean Cell Residence Time (days)
Sludge Age (days)
Lbs BOD/day/lb MLVSS (F/M)
Lbs COD/day/lb MLVSS
Lbs BOD/day/lOOO cu. ft. of aeration
basin
Return Sludge Rate (% of average
plant flow)
1666
1163
5.5
16
4.2
0.7
1.3
54
36
3000 - 6000
3
5
3.5
0.2
0.5
50
5
15
7
0.6
1.0
120
25 - 100
The average MLSS during the study was 1,666 mg/1; however, the MLSS
increased from 1,295 mg/1 on March 1 to 2,180 mg/1 on March 4. According
to plant personnel, large quantities of suspended solids begin carrying over
the clarifier weirs when the MLSS approaches 3,000 mg/1. The WTP prefers to
maintain the MLSS at about 2,000 mg/1.
As shown in Table III, the F/M ratio is slightly high. Assuming the
1975 average flow and influent BOD concentration and a MLVSS concentration
of 1,400 mg/1 (MLSS 70% volatile) the F/M ratio is 0.5, which may be high
for this particular plant. .Influent waste characteristics and MLVSS concen-
tration should be monitored regularly in order to maintain a fairly constant
F/M at a value which consistently results in the best MLSS settleability. By
increasing the MLSS and the return sludge flow rate, and maintaining a F/M
r^tio of about 0.2 - 0.3, activated sludge settleability should be improved.
Dissolved oxygen (DO) concentrations, measured at various depths in the
aeration basin, ranged from 0.8 to 1.2 mg/1. A single 50 hp low speed mechani-
10
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cal aerator supplies oxygen to the basin and there is no flexibility to
control the amount of oxygen supplied.
The results of the settlometer test are presented in Figure 3.
Activated sludge settleability was measured before (station NAB1) and after
(station NAB2) the addition of alum. The sludge settled very rapidly during
the first five minutes of settling, leaving a cloudy supernatant. A slower
settling sludge would leave a clearer supernatant by straining out colloidal
solids.
Wastewater from a commercial laundry is suspected to be adversely
affecting the MLSS settleability. A series of four settlometer beakers were
set up with mixed liquor from the South WTP and 0,3,8, and 15 percent by
volume of laundry wastewater. The results of this bench scale test are pre-
sented in Figure 4. The supernatant was clear in the control sample contain-
ing no laundry wastewater. The supernatant in all samples containing laundry
wastewater were cloudy with a large quantity of colloidal material. The sig-
nificance of this test was that the rate of activated sludge settleability
increased with the addition of wastewater from the commercial laundry, leav-
ing a supernatant containing large quantities of colloidal material. The
increased rate of settling may be partially due to dilution from the laundry
waste; however, the characteristics of the supernatant were due to the laundry
wastewater. The characteristics of the supernatant in the bench scale tests
in the samples containing laundry wastewater were similar to those observed
in the settlometer tests at the North WTP.
Activated sludges and sludge systems can be classified as to their
stability by a microscopic observation of the changes in protozoan species
as floe develops. According to McKinney and Gram (1), during the initial
stage of aeration the flagellates predominate. Flagellates predominate
when the organic concentrations are high and these organisms can easily
compete with the low density of bacteria. With increased development of floe,
the free swimming ciliates predominate, and as the activated sludge reaches
peak efficiency, the stalk ciliates predominate over the free-swimming ciliates.
Free-swimming ciliates are found when there are large numbers of free-swimming
bacteria. The stalked ciliates arise as a result of the number of available
bacteria being reduced below the demands of the free-swimming ciliates. An
optimum activated sludge system will have very few stalked ciliates and,
usually, no other protozoan forms.
A microscopic examination of mixed liquor and return sludge at the North
WTP demonstrate an activated sludge system that lies somewhere between the
initial stage and an optimum sludge. The protozoan population as observed
consisted of flagellates in low densities, a low density of free-swimming
ciliates, and a scarce population of stalked ciliates. The activity of these
organisms appeared inhibited.
« A measure of sludge activity can be determined by utilizing the difference
in"'oxygen uptake rates before and after introduction of the raw waste. The
ratio of these two variables or "load ratio" is calculated as follows:
. DO/min of fed sludge
Load ratio - . - ——
DO/min of unfed sludge
11
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100
o
UJ
Z3
_l
o
>
u
o
Q
D
_1
00
Q
Ui
_1
I-
l-
UJ
v>
FIGURE 3
SETTLOMETER TEST NORTH WTP
TITUSVILLE, FLORIDA
10 15 20 25 30 40
TIME ( MUM )
50
60
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Table IV lists the oxygen uptake rates and calculated load ratios for each
day of observation at the North WTP. The oxygen uptake procedure is presen-
ted in Appendix E. The load ratios in Table IV demonstrate that the sludge
is acclimated to the raw waste. Approximately 5.5 mg/1 of oxygen was depleted
in three minutes demonstrating the rapidity with which oxygen is utilized in
the aeration basin.
TABLE IV
OXYGEN UPTAKE RATES - NORTH WTP
AVERAGE 0,
UPTAKE
DATE
TIME
%RS
(ppm/min)
URS. ±J
(ppm/min)
FRS ±J
LOAD RATIO
FRS/URS
3/1/76
3/3/76
1100
1430
24
35
0.92
0.80
1.88
1.65
2.15
2.06
1/ URS - Unfed Return Sludge Using Clarifier Effluent
2/ FRS - Fed Return Sludge Using Raw Influent
When the raw waste from the North OTP was added to the activated sludge
of the South WTP, there was a short time lag, and oxygen depletion occurred
very slowly with a load ratio of approximately 1.0.
This data, plus the microscopic observations, demonstrates that the raw
influent is not toxic to the sludge system, but does affect the selection of
type and character of microscopic organisms.
Clarifiers
Both circular clarifiers have a center feed, rim take-off flow config-
uration. The east clarifier is a converted primary clarifier with a short
center baffle, and the distribution of incoming flow is near the surface.
The center baffle for the west clarifier extends to near the bottom and pro-
vides better distribution of the influent wastewaters. The measured and
recommended operating parameters for secondary clarifiers following the
complete mix activated sludge process are presented in Table V.
14
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TABLE V
SECONDARY CLARIFIER OPERATIONAL PARAMETERS - NORTH WTP
Measured Recommended (3)(7)
Hydraulic Loading (gpd/sq. ft.)
Solids Loading (lbs/day/sq. ft.)
Hydraulic Detention (hrs)
477
9
400 - 800
20 - 30
East
West
Depth (SWD)
East (ft.)
West (ft.)
2.8(1.4)** 2.5
3.1(1.7)** 2.5
12 - 15*
7.0
7.75
* - Ten State Standards (7), Section 54.12 recommends that final clarifiers
following activated sludge should not t>e less than eight feet deep.
, t*
**- () indicates detention as determined from dye study.
The depths of both clarifiers are less than recommended by Ten State
Standards (7). The shallow depth does cause extreme difficulty in holding
the sludge blanket in the clarifier during any type of stressed condition.
The clarifier effluent weirs were checked and found to be out of level.
The elevation of the east c2arifier weir varied 0.06 feet '(.72 inches) around
the clarifier and the flow around the weir was observed to vary significantly.
The elevation of the west clarifier weir varied 0.03 feet (.36 inches).
The results of the clarifier dye tracer study are presented in Figure 5.
The two curves were projected beyond 150 minutes by checking the exponential
concentration dye-off and determining the additional data points using a
semi-log plot. Location of the centroid of the dye concentration curves is
a measure of the clarifier detention time which was 87 minutes (1.4 hours)
and 100 minutes (1.7 hours) in the east and west clarifiers, respectively.
These detention times are roughly one-half the calculated detention. The
sharp spike exhibited on the east clarifier dye curve demonstrates short
circuiting which probably results from the level of the effluent weir and the
short center baffle. The short center baffle works well in a primary clari-
fier with the heavy influent solids; however, secondary clarifiers are more
dependent on the upflow velocity and the influent should be distributed closer
to the bottom.
The area under the curves in Figure 5 are an indication of the flow
split to the two clarifiers. According to the areas under the dye concen-
tration curves, the east and west clarifiers are handling about 52 and 48
p*ercent of the flow, respectively.
The dissolved oxygen concentration (DO), was measured at about the three
foot depth in each clarifier on March 2. These concentrations in the east
and west clarifiers were 0.4 and 0.0 mg/1, respectively.
15
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r,200
K UJ 600
FIGURE 5
CLARIFIER DYE TRACER STUDY
NORTH WTP
TITUSVILLE, FLORIDA
AREA CENTROID
East Clarifier .895 87 Min.
West Clarifier .8 19 100 Min.
200 250 300
TIME ( MINUTES)
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Chlorine Contact Chamber
The calculated hydraulic detention time in the chlorine contact chamber
(CCC) at design flow is approximately 40 minutes. However, observation of a
dye flowing through the CCC indicated the actual detention time to be only
a few minutes and well defined short-circuiting was observed. This phenom-
enon is probably due to the size of the baffle openings and roughness of
the concrete. The primary concern with a CCC is bacterial kill which was
adequate according to VJTP records.
The typical chlorine usage was approximately 70-80 pounds per day,
which resulted in an average measured residual chlorine concentration of
2.8 mg/1. Careful monitoring of residual chlorine in order to maintain
a 0.5 mg/1 residual will significantly reduce chemical costs.
Anaerobic Digesters
The two anaerobic digesters are not heated or covered and are operated
in series. During the study, the primary digester was upset (high volatile
acid concentration and low pH); therefore, sludge wasting was to the secon-
dary digester only. The digester upset was due to the excessive quantity of
alum sludge. Approximately 17,000 gallons/day of solids from the digester
are hauled by truck to a land disposal site or discharged to sludge drying
beds.
Laboratory
The laboratory at the North WTP is equipped for routine control testing
and limited analytical work. Most sample analyses are performed at the South
WTP laboratory.
17
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SOUTH WASTEWATER TREATMENT PLANT
TREATMENT FACILITY
Treatment Processes
A schematic diagram of the 2 mgd South 'WTP is presented in Figure 6.
Design data are enumerated in Table VI. The plant began operation in 1967
and serves a population of approximately 9,000. No major industrial wastes
are received at the South OTP.
The South WTP is operated in the complete-mix activated sludge mode.
Sludge is returned from both clarifiers back to the aeration basin. Waste
sludge is pumped to the anaerobic digester after which it is either dis-
charged onto the sludge drying beds or hauled by truck to a land disposal
site.
The grit removal system was designed similar to the system at the
North WTP with the same poor results. The final effluent is chlorinated
in the pump station wet well and pumped about one mile through a 20-inch
force main to the Indian River.
Personnel
The plant is staffed by six persons holding the following operator
classifications: 1-A, 1-B, 2-C, 1-LCO, and one trainee.
STUDY RESULTS AND OBSERVATIONS
A complete listing of all analytical data and general study methods
are presented in Appendices A and B. Formulae used for general calcula-
tions are enumerated in Appendix C. Significant results and observations
made during the study are discussed in the following sections.
Flow
Plant flow is measured with a 12-inch Parshall flume equipped with
a recorder and totalizer. Return sludge flow is also measured utilizing
a ,venturi meter, recorder, and totalizer.
Average hourly plant effluent flows during March 1-4, 1976, are
presented in Figure 7. The average effluent flow during the study period
was 0.94 mgd and the average flow for 1975 was approximately 1 mgd (approxi-
mately 50 percent of design.) The average return sludge flow during the
study was 0.34 mgd.
18
-------
Inf fuen f
-------
TABLE VI
DESIGN DATA - SOUTH WTP
TITUSVILLE, FLORIDA
FLOW MEASUREMENT
Final Effluent
Return sludge
Design flow
Average flow
12 in. Parshall flume, recorder,
totalizer
Ventuiri meter
2 mgd
1 mgd (1975 monthly average)
0.94 mgd (study period average)
AERATION BASIN
Diameter
SWD
Center depth
Aeration
Volume
70 ft.
15.8 ft.
20 ft.
1-60 hp aerator
66,192 cu. ft. (0.5 m.g.)
CLARIFIERS
Number
Diameter
SWD
Center depth
Area
Volume
Weir length
2
50 ft.
9.8 ft.
11.6 ft
1,963 sq
19,237 cu
142 ft.
ft.
f t.
(0.14 m.g.)
ANAEROBIC DIGESTER
Number
Diameter
SWD
Center depth
Volume
1 (not covered)
50 ft.
20 ft.
28 ft.
44,506 cu. ft. (0.34 m.g.)
PUMPS
Return sludge
Effluent
Waste Sludge
Digester recirculation
2-1400 gpm
2-2400 gpm
2-200 gpm
350 gpm
20
-------
FIGURE 7
PLANT FLOW
SOUTH PLANT
TITUSVILLE, FL
5 AH 1
—ir
6 PM
6 AM
3/3
Wed.
-------
Waste Characteristics and Removal Efficiencies
Table VII presents an average chemical description of the South WTP
influent and effluent with calculated percent treatment reductions shown
for all parameters. The supernatant return pump was accidentally left on
during the period March 1-3; consequently, influent samples during this
period were not representative of influent waste characteristics and are
not included in Table VII.
TABLE VII
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
SOUTH WTP
? /
Influent—
Effluent
Parameter
(mg/1)
(mg/1)
% Reduction
do!/
0.3
6.5.
bod5
246
11
89
COD
432
51
88
TSS
85
2
98
VSS
80
2
97
Total Solids
624
479
23
Total Volatile Solids
210
77
63
Settleable Solids (ml/1)
12
< 0.1
> 99
TKN-N
39.7
16.2
59
NH -N
27
12.3
54
NO;:-NO 2-N
< 0.01
0.92
—
Total Phosphorus
9.9
6.8
31
1/ - Grab samples on March
1, 1976
2/ - Analyses based on single 24-hour
composite sample
collected
during March 3-4.
Aeration Basin
Grab samples were taken from the aeration basin and analyzed for
TSS, VSS, percent solids by centrifuge and settleability as determined
by the settlometer. Presented in Table VIII are various activated sludge
operational parameters calculated during the study period and the corres-
ponding recommended values for the complete-mix activated sludge process.
Measured values were calculated using the average 1975 flow of 1 mgd.
22
-------
TABLE VIII
AERATION BASIN OPERATIONAL PARAMETERS - SOUTH WTP
Measured* Recommended (2) (5)
MLSS 2,135 3,000 - 6,000
MLVSS 1,840
Hydraulic Detention Time (hrs) 9 3-5
Mean Cell Residence Time (days) 6 5-15
Sludge Age (days) 12,5 3.5 - 7
Lbs BOD/day/lb MLVSS (F/M) 0.27 0.2 - 0.6
Lbs COD/day/lb MLVSS 0.47 0.5 - 1.0
Lbs BOD /day/1,000 cu. ft. of aeration basin 31 50 - 120
Return Sludge Rate (% of average plant flow) 34 25 - 100
* - Influent BOD^, COD, and TSS values from March 3-4 composite sample only.
Dissolved oxygen concentrations were measured at one foot intervals
through the first eight feet of depth in the aeration basin. Measured DO
concentrations varied from 1.2 to 0.9 mg/1. A single 60 hp mechanical
aerator supplies oxygen to the basin and there is no flexibility to control
the amount of oxygen supplied.
The results of the settlometer test are presented in Figure 8. The
sludge settles slowly, leaving a clear supernatant. As long as the sludge
blanket can be held down, this sludge should produce a clear supernatant and
acceptable effluent.
A microscopic examination of mixed liquor and return sludge demonstrate
an active activated sludge system heavily populated with free swimming ciliates,
stalked ciliates, and rotifers. These organisms are indicative of a fairly
stable activated sludge system. Sludge mass at the South WTP was denser and
floe formation was more distinct than that of the North WTP, although filamentous
growth could be a sign of possible future problems.
Oxygen uptake rates and calculated load ratios for these wastes are
presented in Table IX. The load ratios were generally within the average range
of 2 to 4 for conventional/complete mix activated sludge processes.
OXYGEN
TABLE IX
UPTAKE RATES -
SOUTH OTP
DATE
TIME
% RS
Average
(ppm/min)
URSi/ "
O2 Uptake
(ppm/min)
FRS y
LOAD RATIO
FRS/URS
3/1/76
3/2/76
3/3/76
1605
1500
35
36
45
0.77
1.1
0.76
1.8
1.9
1.56
2.34
1.72
2.08
1/ URS - Unfed return sludge using clarifier effluent.
2/ FRS r- Feed return sludge using raw influent.
23
-------
100
90
80
70
60
50
40
30
20
10
0
FIGURE 8
SETTLOMETER TEST SOUTH WTP
TITUSVILLE, FLORIDA
1_J L
15 20 25 30
TIME (MINI
40
50
60
-------
Clarifiers
Both clarifiers have a center feed, rim take-off flow configuration. The
measured and recommended operational parameters for secondary clarifiers follow-
ing the complete mix activated sludge process are presented in Table X.
TABLE X
SECONDARY CLARIFIER OPERATIONAL PARAMETERS-SOUTH WTP
Measured Recommended (3)(7)
Hydraulic Loading (gpd/sq. ft.) 255 400-800
Solids Loading (Ibs/day/sq.ft.) 4.5 20-30
Hydraulic Detention (hrs) 6.7 2.5
SWD (ft) 9.8 12-15
The South WTP is operating at approximately 50 percent of its design
capacity and this is reflected in Table X. The depth to the sludge blanket
below the water surface varied from 6.9 to 7.8 feet, which is satisfactory.
Chlorine Contact Chamber
Approximately 100 pounds of chlorine are added to the clarifier
effluent daily. The contact time is accomplished in the mile long discharge
pipe to the receiving stream.
Anaerobic Digester
The anaerobic digester is not covered. Proper sludge conditioning
and solids separation is not accomplished; consequently, most of the sludge
from the digester is hauled to a land disposal site. A small portion of
sludge is discharged onto the sludge drying beds.
Laboratory
During the study period, EPA laboratory personnel were located at the
Titusville - South WTP and had the opportunity to work with and observe
testing being done by plant laboratory personnel. The testing' program was
thorough in kinds of analysis which were run, and complete regarding fre-
quency of sampling and sampling locations through the plant. Laboratory
personnel were conscientious and highly capable. The laboratory area was
neat, adequate- space was provided, laboratory instruments were of good
quality and were maintained in good working order.
On March 3-4, four composite samples were split for testing by both
EPA and the City of Titusville. Samples were tested for BOD^, COD, TSS,
VSS, and total phosphorus. The results of the split samples are presented
in Table XI. Precision control limits established for duplicate analysis
at the EPA laboratory in Athens, Georgia were used as a tool to determine
25
-------
TABLE XI
SPLIT SAMPLE COMPARISON
EPA - TITUSVILLE
MARCH 3-4, 1976
Parameter
Sample
Station
(mg/1)
EPA
(mg/1)
Titusville
Titusville
% Difference
from mean
BOD 5
NI
NE
SI
SE
239
15
246
29
212
13.5
202
17.8
-6%
-5%
-9.8%
-24%
A
A
A
A
COD
NI
NE
SI
SE
524
72
432
56
698.5
169
525.6
97
+14.3%
+40%
+ 9.8%
+27%
A
X
A
X
TSS
NI
NE
SI
SE
156
12
85
3
210
13
154
9
+14.8%
+ 4%
+29%
+50%
A
A
A
*
VSS
Total
Phos.
NI
NE
SI
SE
NI
NE
SI
SE
142
12
80
3
9.7
0.9
9.9
5.8
186
13
146
9
26.01 £f"
0.612 ,P
29.07 i.r
13.46 VH
+13.4%
+ 4%
+29%
+50%
+4-6-%-
-1-9%
+4-9-%
+39-%-
-L.C.%
- W
-I-?.
/V£
¦k*
.Yr A
-fr A
-X' A
A
A = Within acceptable range for duplicate samples
* = Acceptable, because of low results.
** = Acceptable range not available on VSS.
X = Duplicates not acceptable, % difference greater than upper control
limit at Athens, Georgia EPA lab.
yzC*
26
-------
whether, the difference between duplicate results was acceptable or unaccept-
able. jThe range of phosphate results on all four samples and the COD of
the two effluent stations exceeded precision control limits for duplicate
samples run at the Athens laboratory. The BOD^, COD influent and suspended
solids results were within the range of acceptable precision?] Precision
control limits for volatile suspended solids are presently unavailable.
Undoubtedly, some differences in values can be attributed to comparing re-
sults of two different laboratories, different analyses, a difference in
sample holding time, and in some cases, an entirely different analytical
method.
In an effort to determine which factors influenced differences in
results, the Titusville laboratory agreed to run control samples supplied
by the EPA Quality Assurance Section in Cincinnati, Ohio. These reference
samples were run for TKN-N, COD, and total phosphorus. COD results indi-
cated a continued problem,. but TKN and total phosphorus results matched very
well with known values. /According to Titusville laboratory personnel,
the discrepancy in phosphorus results on the split sample could have been
due to contamination of glasswar^T] A comparison of values obtained by
the Titusville laboratory versus known values of reference samples are
shown in Table XII.
Continued quality control work is being performed by the Titusville
laboratory in an effort to resolve the question on COD.
TABLE XII
ANALYSIS OF REFERENCE SAMPLES
Parameter
Known Value
Titusville Lab
Kj eldahl-N
5.80 mg/1
5.6 mg/1
Total Phosphorus
0.713 mg/1
0.8 mg/1
COD
370 mg/1
260 mg/1
27
-------
The Titusville laboratory used a one liter graduated cylinder for the
SVI test. Differences in the 30 minute settleability were observed between
the City's results and those by EPA, using the two liter settlometer. These
differences observed for the slow settling South WTP activated sludge are
shown in Table XIII. The comparison was not as pronounced at the North WTP,
due to the extremely rapid settling rate. Although only two comparisons
are available and the sample times were not identical, the slower settling
in the one liter cylinder could be due to increased surface tension of the
narrower diameter container.
Upon the recommendation of EPA personnel, the Titusville laboratory
now use two liter beakers (settlometers) to determine activated sludge
settleability.
The laboratory has a spectrophotometer which may be used for turbidity
analysis. Turbidity standards should be prepared as discussed in Standard
Methods (8) and a calibration curve constructed in the 0 to 40 NTU range
at 5 NTU intervals. The necessary chemicals have already been ordered by
Titusville laboratory personnel to prepare these standards.
Laboratory personnel presently pipet seed directly into BOD bottles.
Seeding a large container of dilution water might give more consistent seed
depletions.
An errata sheet for the 1974 EPA Methods Manual has been sent to the
Titusville Laboratory. According to Mr. Tom Bennett, Chief of the Chemistry
Section, Laboratory Services Branch, Surveillance and Analysis Division, pre-
servation of samples for nitrogen series and total phosphorus analysis with
10 mis of 10 percent sulfuric acid per liter is an accepted standard method.
TABLE XIII
EPA - TITUSVILLE SETTLEABILITY COMPARISON
% Settling After 30 minutes
DATE
STATION
TITUSVILLE
EPA
May 1
May 2
May 3
May 4
May 1
May 2
May 3
May 4
SAB
SAB
SAB
SAB
NAB 2
NAB2
NAB 2
NAB 2
89
93
92
83
10
13
13
11
17
17
62
60 *
13.5
16
* Is an average of morning and afternoon readings
28
-------
REFERENCES
1. .McKinney, Ross E. and Gram, Andrew. "Protozoa and Activated Sludge",
Sewage and Industrial Waste 28 (1956):1219-1231.
2. "Operation of Wastewater Treatment Plants", A Field Study Training
Program, US-EPA, Technical Training Grant No. 5TT1-WP-16-03, 1970.
3. "Process Design Manual for Suspended Solids Removal", US-EPA Technology
Transfer, January 1975.
4. "Sewage Treatment Plant Design", American Society of Civil Engineers,
Manual of Engineering Practice No. 36, 1959.
5. "Wastewater Engineering", Metcalf and Eddy, Inc., 1972.
6. West, Alfred W., Operational Control Procedures for the Activated
Sludge Process. Part I, Observations, EPA-330/9-74-001-a, April 1973.
7. "Recommended Standards for Sewage Works", Great Lakes - Upper
Mississippi River Board of State Sanitary Engineers, Revised Edition,
1971.
8. "Standard Methods for the Examination of Water and Wastewater", 13th
Edition, 1971.
29
-------
AAA-***&&
APPENDIX
*£&&&& Ask
-------
TITUSVILLE. FLORIDA - NORTH AND SOUTH WTP
North Plant - Titusvllle, Florida
-------
data
TITUSVILLE, FLORIDA - NORTH AND SOUTH WTP
North Plant - Tltusvllie, FL (contiauad.),
-------
APPENDIX A
LABORATORY DATA
TITOSVIIiE, FLORIDA - [s'ORTH AiND SOUTH V.TP
South Plant - Tltusvllle, Florida (continued)
1
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-------
APPENDIX A
LABORATORY DATA
TITUSVILLE, FLORIDA - NORTH AND SOUTH WTP
South Plant - Titusville, Florida
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-------
APPENDIX B
GENERAL STUDY METHODS
To accomplish the stated objectives, the study included extensive
sampling, physical measurements and daily observations. Plant influent
and effluent sample stations were sampled for three consecutive 24-hour
periods with ISCO Model 1392-X automatic samplers. Aliquots of sample
were pumped at hourly intervals into individual refrigerated glass bottles
which were composited proportional to flow at the end of each sampling
period.
Dissolved oxygen was determined at stations throughout the plant and
in the aeration basins using a YSI Model 51A dissolved oxygen meter.
The plant flow totalizer was used to determine total daily flow and
the recorder was used for hourly flows.
Temperature was recorded while measuring the dissolved oxygen con-
centration. Individual samples of a 24 hour compositing period were used
to determine hourly influent pH variation.
Depth of the secondary clarifier sludge blankets were determined
daily using equipment suggested by Alfred W. West, EPA, NFIC Cincinnati. (6)
Sludge activity was determined by the oxygen uptake procedure presented
in Appendix E.
A series of standard operational control tests were run daily:
o Settleability of mixed liquor suspended solids (MLSS) as
determined by the settlometer test;
o Percent solids of the mixed liquor and return sludge
determined by centrifuge;
© Suspended Solids and Volatile Suspended Solids analysis on
the aeration basin mixed liquor and return sludge;
© Turbidity of each final clarifier effluent.
An amperometric titrator (Fischer & Porter Model 17T1010) was used
to determine effluent chlorine concentrations.
BOD5 samples were set up by EPA personnel and the final dissolved,
oxygen concentrations were determined by laboratory personnel at the
Titusville, Florida Wastewater Treatment Plant.
Visual observations of individual unit processes were recorded.
34
-------
Mention of trade names or commercial products does not constitute
endorsement or recommendation for use by the Environmental Protection
Agency.
35
-------
APPENDIX c
Activated Sludge
Formulae Used For General Calculations
Aeration Basin
lbs. of solids in aeration basin
Basin volume = m.g.; MLSS (conc.) = mg/1
(MLSS cone) x (Basin vol.) x 8.34 = lbs. of solids
Aeration basin loading (lbs. BOD or COD/day)
Inf. flow to aeration basin = mgd
Inf. BOD or COD = mg/1
Qtsujj or (^ujj; x xxuw w L>. — xu^>. jjujj or 'Csju/aay
10
Sludge Age (days)
MLSS conc. (avg. of daily values) = mg/1
Aeration Basin Vol. = m-.g.
TSS, Primary Eff. or Basin Inf. conc. = mg/1
Plant Flow = mgd
(MLSS) x (Basin Vol.) x (8.34)
(TSS) x (Flow) x 8.34
Sludge Vol. Index (SVI)
30 min. settleable solids (avg. of daily values) =
MLSS conc. = mg/1
(%, 30 min. set. solids) x (10,000)
MLSS
Sludge Density Index (SDI)
SVI Value 100
SVI
Detention time (hours)
Volume of basins =|ftgal.
Plant flow =^gal./day
Return sludge flow gal./day
Basin volume x 24
(Flow) + (Return sludge flow)
F/M Ratio (Food/Microorganism) BOD or COD
Basins Inf. BODg conc. (avg. or daily value) = mg/1
Basins Inf. COD conc. (avg. or daily value) = mg/1
Plant Flow = mgd
MLVSS conc. (avg. or daily value, note Volatile SS) = mg/1
Basin Vol. - m.g.
iBODgconc ) x (plantflow) x (8.34) = lbs_ B0D/lb. MLV£
(MLVSS) x (Basin Vol.) x 8.34 '
36
-------
(COD cone.) x (plant flow) x (8.34) _ vp0D/lb MIVSS
(MLVSS) x (Basin Vol.) x (8.34) lbs.vCOD/lb. llLVbb
8. Mean cell residence time (MCRT) = days
MLSS cone. (avg. or daily value) = mg/1
Basin vol. = m.g.
Clarifier vol. = mvg.
Waste activated sludge cone. = mg/1
Waste activated sludge flow rate-mgd
Plant effl. TSS = mg/1
Plant flow = mgd
(MLSS) x (Basin vol. + Clarifier vol.) x 8.34 _
' ^ it—^ ~ —j. ^ — j—3 —. t j^ ^ ^ ^ \ -,r (?TT <¦> ^ ^ >.r o o a _l ~ days
\ •» W V* o -x, y ^ ^ ^ — w • , ~ S •« —— - - - - ^ - / — - • — -
(Plant effl. TSS x plant flow x 8.34)
Clarifier
1. Detention time = hours
/--Plant flow to each clarifier = gals/day
/ Individual clarifier vol. = gals.
I — (clarifier Vol. (each) x 24 _ hours
P* Plant f low + Return Sludge Flow-
2. Surface loading rate = gal./day/sq. ft.
Surface area/clarifier = sq. ft.
plant flow to ciarifier = gal./day
Plant flow to clarifier = gal./day/s ft_
Clarifier surface area
3. Weir Overflow Rate (gal./day/lin. ft.)
Weir Length = ft.
Plant flow to clarifier = gal./day
Plant flow , , ,
™^ rr - gal./day/lin . ft.
Welr length b ' J'
37
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u
^ -«•««-,Mr M II) N ICu -fm
appendix d
fietur" Sludge Flow
North WTP
Titusvilie; FL
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appendix e
OXYGEN UPTAKE PROCEDURE U
A. Apparatus
1. Electronic DO analyzer and bottle probe
2. Magnetic stirrer
3. Standard BOD bottles (3 or more)
4. Three wide mouth sampling containers (approx. 1 liter each)
5. DO titration assembly for instrument calibration
6. Graduated cylinder (250 ml)
/. Adapter for connecting two BOD bottles
B. Procedure
1. Collect samples of return sludge, aerator influent and final
clarifier overflow. Aerate the return sludge sample promptly,
2. Mix the return sludge and measure that quantity for addition
to a 300 ml BOD bottle that corresponds to the return sludge
proportion of the plant aerator, i.e. for a 40% return sludge
percentage in the plant the amount added to the test EOD
bottle is:
300 X .4 = 120 - 86 ml
1.0 + . .4 1.4
3. Carefully add final clarifier overflow to fill the BOD bottle
and to dilute the return sludge to the plant aerator mixed
liquor solids concentration.
4. Connect the filled bottle and an empty BOD bottle with the
BOD bottle adapter. Invert the combination and shake vigorously
vhile transferring the contents. Re-invert and shake again
vhile returning the sample to the original test bottle. The
sample should now be well mixed and have a high D.O.
5. Insert a magnetic stirrer bar and the previously calibrated
DO probe. Place on a magnetic stirrer and adjust agitation
to maintain a good solids suspension.
6. Read sample temperature and DO at test time t~0. Read and
record the DO again at 1 minute intervals until at least 3
consistent readings for the change in DO per minute are
obtained (ADO/min). Check the final sample temperature.
This approximates sludge activity in terms of oxygen use
after stabilization of the sludge during aeration (unfed
sludge activity).
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Appendix E (cont'd)
7. Repeat stops 2 through 6 on a replicate sample of return
sludge that has been diluted with aerator influent (fed
mixture) rather than final effluent. This A DO/minute
series reflects sludge activity after mixing with the new
feed. The test results indicate the degree of sludge
stabilization and the effect of the influent waste upon
that sludge.
The load factor (LF), a derived figure, is helpful in evaluating
sludge activity. It is calculated by dividing the DO/min of fed sludge
by the DO/min of the unfed return sludge. The load ratio reflects the
conditions at the beginning and end of aeration. Generally, a largp
fnzzz~ abuudauL, m-ccpLdulc It;eu unuer favoraDle conditions. A
small LF means dilute feed, incipient toxicity, or unfavorable conditions.
A negative LR indicates that something in the wastewater shocked or
poisoned the "bugs."
1/ Taken from "Dissolved Oxygen Testing Procedure," F. J. Ludzack and
script for slide tape XT-43 (Dissolved Oxygen Analysis - Activated Sludge
Control Testing) prepared by F. J. Ludzack, NERC, Cincinnati.
40
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