TECHNICAL ASSISTANCE PROJECT
AT THE
MAIN WASTEWATER. TREATMENT PLANT
MT. PLEASANT, SOUTH CAROLINA
-------
EPA 904/9-77-031
TECHNICAL ASSISTANCE PROJECT
AT THE
MAIN mSTEWATER TREATMENT PLANT
MT. PLEASANT, SOUTH CAROLINA
ENVIRONMENTAL PROTECTION AGENCY
SURVEILLANCE AND ANALYSIS DIVISION
ATHENS, GEORGIA
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TABLE OF CONTENTS
Page
Introduction 1
Sumnary 2
Recomnendations 3
Treatment Facility 4
Treatment Processes 4
Personnel 4
Study Results and Observations 7
Flow 7
Waste Characteristics and Removal Efficiencies 7
Contact and Reaeraticm Basins 8
Clarifiers 11
Chlorination 13
Aerobic Digester 13
Laboratory 13
References 15
Appendices
A. Laboratory Data
B. Dissolved Oxygen Data
C. General Study Methods
D. Project Personnel
E. Oxygen Uptake Procedure
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LIST OF FIGURES
Page
1. Main Wastewater Treatment 5
2. Activated Sludge Settleability 10
3. Clarifier Dye Study 12
LIST OF TABLES
I. Design Data 6
II. Wastewater Characteristics and Removal Efficiencies 8
III. Activated Sludge Operational Parameters 8
IV. Secondary Clarifier Operational Parameters 11
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INTRODUCTION
A technical assistance study of operation and maintenance
problems at the Main Wastewater Treatment Plant, Mt. Pleasant,
South Carolina was conducted July 25-29, 1977 by the U.S. Environmental
Protection Agency (US-EPA) Region IV, Surveillance and Analysis
Division. Operation and maintenance technical assistance studies
are designed to assist wastewater treatment plant personnel in
maximizing treatment efficiencies as well as assisting with
special operational problems.
The selection of this plant was based on a request from the
South Carolina Department of Health and Environmental Control
(SC-DHEC). The study was coordinated with the US-EPA Enforcement
and Water Divisions and SC-DHEC. The specific study objectives
were:
(1) To optimize treatment through control testing and
recommended operation and maintenance modifications;
(2) To introduce and instruct plant personnel in new
operation control techniques;
(3) To determine influent and effluent wastewater character-
istics ;
(4) To assist laboratory personnel with any possible laboratory
procedure problems; and
(5) To compare design and current loading data.
A follow-up assessment of plant
practices will be conducted through uti?i?a^ a^d maintenance
by plant personnel. If necessary subsem^i°,n-°? daCa
will be made. The follow-up assessment Sill determine",'fa"1:
recommendations were successful in !rLe^tu;LIie n
if further assistance is required. plant operations and
The cooperation of personnel from the> qr nmrr • ^
acknowledged. The technical assistance team is Srajefu.11y
appreciative for the cooperation and assistance 7
personnel of the City of Mt. Pleasant, S^uth cSroUna^
1
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SUMMARY
The 1.4 mgd Main WTP was originally placed in operation in 1970 as
a contact stabilization activated sludge process. The average flow during the
study wis 0.83 mgd, essentially all of which was domestic wastewater. The
reductions in BOD5 and TSS during the study period were 87 and 86 percent,
respectively.
Major study observations are listed below:
(1) The contact and reaeration basins contained an excessive quantity
of what appeared to be old sludge.
(2) Aerators in the contact and reaeration basins were operated on
timers. Dissolved oxygen concentrations were generally low and
dropped rapidly to critically low concentrations when the aerators
were off.
(3) A thick mat of foam completely covered all aeration basins and
clarifiers.
(4) Filamentous organisms V7ere observed in the foam and activated sludge
which partially accounted for the observed sludge settleability.
(5) Equal flow to each of the four final clarifiers was difficult to
maintain. Solids were ofter observed flowing out of individual
basins as flows to the clarifiers became unbalanced, especially
during evening high flows when the WIP was not staffed.
(6) No sludge blanket was present in the final clarifiers.
(7) Excessive oil and grease was present in the influent wastewater.
(8) The average total chlorine residual was 3.3 mg/1 based on the
amperometnc back titration method. Analysis of the saroe sanples
by WTP personnel using the orthotolidine color comparater yielded
1.5 mg/1 chlorine.
2
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RECOMMENDATIONS
Based on observations and data collected during the study, it is recorrnend-
ed that the following measures be taken to improve wastewater treatment and plant
operation. By observing treatment responses to gradual process changes, optimum
treatment efficiency can be obtained.
1. The rate of sludge wasting should be increased. This will reduce
the sludge age and assist in removing the filamentous organisms. The
target range for the F/M ratio should be 0.2 to 0.6.
2. The return sludge flow rate should be reduced in order to develop
a sludge blanket and greater return sludge solids concentration.
3. The dissolved oxygen concentrations in the aeration and reaeration
basins should be maintained at about 1-2 mg/1. This will require
operating the aerators continuously.
4. The WTP should be staffed at least 16 hours per day. An operator
could maintain approximate equal flow to the clarifiers during evening
high flows.
5. Foam, scum and other floatable material should not be returned to
the head of the WTP. Reduction of the sludge age should relieve the
foaming problem especially if the existing material could be wasted
or removed from the system.
6. Restaurants and other possible sources of oil and grease should be
inspected to assure adequate grease removal at these sources.
7. Use of the amperometric back, titration method for chlorine residual
would effect a monetary savings through a reduction in chlorine usage.
3
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TREATMENT FACILITY
TREATMENT PROCESSES
A diagram of the 1.4 mgd Main WTP is presented-in Figure 1 and design
data are listed in Table I. The influent wastewater was primarily domestic
in origin. The WTP was completed in 1970 as a 1.1 mgd contact stabilization
activated sludge process. In 1976 the WTP was upgraded to a 1.5 mgd facility by
the addition of a grit chamber, an additional return sludge pump and larger
return sludge lines.
Return sludge was stabilized in the reaeration basin and then returned to
the contact basin to react with the raw wastewater. Biological solids were
removed by four secondary clarifiers operated in parallel. Clarified wastewater
was chlorinated and discharged into the Intracoastal Waterway. Scum, foam and
other floatable materials were returned to the main influent pump station. Waste
solids were conditioned in an aerobic digester and then dewatered on sand
drying beds.
The digester aerator remained on at all times. Aerators in the contact
and reaeration basins were on timers. The contact basin aerator was operated on
a 15-minute cycle. The two reaeration basin aerators were operated on a 30-minute
cycle, with at least one aerator on at all times.
PERSONNEL
The WIP was manned eight hours per day by eight persons who also had
additional responsibility for 30 lift stations, 2 package treatment plants, 1
lagoon and a 0.3 mgd activated sludge WTP. The staff held the following waste-
water classifications: 1-A, 1-B, 2-C, 1-D, 2-trainees and one laborer.
4
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FIGURE 1
Main Wastewater Treatment Plant
Mt. Pleasant, South Carolina
Propeller
Flow
Meter
\ Chlorine
i~6-a
Ln
ME
T o*~
Intracoastal chlorine
Waterway Contact
Chamber
Sludge
Drying Beds
N
MC MC MC MC
4 3 2 1
Reaeration Basin
MRA
Contact Basin
©
Return Sludge
Pumps
Return Sludge
Scum Overflow
®25 hp Mechanical Aerator
a Sampling Stations
Wastewater Flow
Sludge Flow
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TABLE I
DESIGN DATA
FLOW MEASUREMENT
Design Flow
Effluent
Return Sludge
Waste Sludge
CONTACT BASIN
Dimensions
Volume
Aeration
REAERATION BASIN
Dimensions
Volume
Aeration
FINAL CLARIFIERS
Number
Dimensions
Total Surface Area
Total Volume
Weir Length
CHLORINE CONTACT CHAMBER
Dimensions
Volume
DIGESTER
Dimensions
Volume
Aeration
PUMPS
Influent
Return Sludge
DRYING BEDS
Number
Dimensions
Total Area
1.4 mgd
Propeller Meter
None
None
48.7 x 48.7 x 9 ft.
21,390 cu. ft. (0.16 m.gal)
1 - 25 hp (mechanical)
48.7 x 100 x 9 ft.
43,875 cu. ft. (0.33 m.gal)
2 - 25 hp (mechanical)
4
48.7 x 12 x 8.5 ft.
2,338 sq. ft.
19,870 cu. ft. (0.15 m.gal.)
180 lin. ft.
25 x 25 x 5 ft.
3,125 cu. ft. (0.02 m. gal.)
48.7 x 48.7 x 9 ft.
21,390 cu. ft. (0.16 m. gal.)
1 - 25 hp (mechanical)
2 - 1,710 gpm variable speed
3 - 500 gpm variable speed
3
35 x 80 ft.
8,400 sq. ft.
6
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STUDY RESULTS AND OBSERVATIONS
A complete listing of all analytical data and general study methods
are presented in the Appendices. Significant results and observations made during
the study are discussed in the following sections.
FLOW
Plant flow V7as measured by a propeller meter located at the entrance to
the chlorine contact chamber and transmitted to a recorder and totalizer. The
average flow during the study and for the month of July 1977 was 0.83 and 0.71
ingd, respectively. Plant personnel stated that excessive inflow and infiltration
were a problem during wet weather and high tides.
A rough check of the flow raster, using the rectangular weir located at
the effluent from the grit chamber, indicated the meter and recorder to be
operating properly.
There was no means available to measure return sludge and waste sludge
flows. Flow devices for these waste streams were initially constructed into
the WIP, but cronic malfunction made them useless and led to their removal.
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
The pH throughout the plant varied from 7.0 to 7.4 except for a single
effluent sample on July 28, which had a pH of 6.4.
A chemical description of the influent and effluent wastewaters with
calculated percent reductions is presented in Table II.
Analyses were conducted on 24-hour, flow proportional, composite samples,
collected on three consecutive days during the study period; and percent reductions
were calculated from the averaged results. Chlorine residual analyses were
conducted on grab samples and the results were averaged. Oil and grease was
analyzed from a single grab sample.
The Influent BOD5 (139 mg/1), TS (3,408 mg/1) and TSS (429 mg/1)
concentrations indicated a low organic strength waste with a high solids content.
The influent chloride concentration (1,324 mg/1) represented 39 percent of the
total solids and 44 percent of the total soluble solids concentrations. This
chloride concentration was extremely high for domestic waste and indicated an
infiltration problem. The WTP reduced the influent BOD5 and TSS by 87 and 86
percent. NPDES permit limits were exceeded for TSS primarily due to excessive
solids lost during evening high flows. The influent oil and grease concentration
(43 mg/1) was exceptionally high for domestic wastewater (14).
7
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TABLE II
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
MT. PLEASANT MAIN WTP
PARAMETER
BOD5
COD
TOC
TS
TVS
TSS
VSS
TKN-N
NH3-N
NO3-NO2-N
TOTAL PHOSPHORUS
LEAD
CHRCMIUM
COPPER
CADMIUM
ZINC
Cl2 RESIDUAL
CHLORIDE
OIL AND GREASE
INFLUENT
(mg/1)
139
529
94
3,408
637
429
297
21.8
16.2
<0.01
12.2
0.076
<0.080
0.390
<0.010
0.249
1,324
43
EFFLUENT
(mg/1)
18
145
19
2,764
340
62
33
10.6
9.1
0.77
6.4
<0.050
<0.080
0.057
<0.010
0.069
3.30
1,158
REDUCTION
a)
87
73
80
19
47
86
89
51
44
48
>34
85
72
13
CONTACT AND REAERATION BASINS
Grab samples were collected daily from the contact and reaeration basins
and analyzed for TSS, VSS and percent solids as determined by the centrifuge.
Settleability of the activated sludge in the contact basin was determined by the
settlorreter. Presented in Table III are various activated sludge operational
parameters based on data collected during the study and the corresponding
recommended values for the contact stabilization activated sludge process.
TABLE III
ACTIVATED SLUDGE OPERATIONAL PARAMETERS
MEASURED
RECOMMENDED (2)(5)(9)
Contact Detention Time (min)
Reaeration Detention Time (hrs)
Contact TSS Concentration (mg/1)
Reaeration TSS Concentration (mg/1)
Lbs. B0D5/day/lb VSS (F/M)
Lbs. COD/day/lb. VSS
Lbs. BOD^/day/1000 cu. ft.
aeration basin
Return Sludge Rate (7= of average plant
flow)
it
30 -
60
*
2 -
6
2,387
1,000 -
3,000
7,422
4,000 -
10,000
0.06
0.2 -
0.6
0.22
0.5 -
1.0
15
40 -
75
*
25 -
100
* Could not be measured.
8
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The F/M ratio of 0.06 indicates excessive solids in the aeration and
reaeration basins for the waste load received. The solids concentrations should
be reduced in order to maintain an approximate F/M ratio of 0.3.
Air was supplied to the contact basin by a single 25 hp mechanical
aerator and to the reaeration basin by two 25 hp mechanical aerators. Dissolved
oxygen (DO) concentrations measured in these basins are presented in Appendix B.
Generally, DO concentrations were less than the optimum range of 1-2 mg/1.
Dissolved oxygen concentrations dropped rapidly to critically low concentrations
when the aerators were off. According to plant personnel, leaving the aerators on
at all times resulted in tremendous accumulations of foam.
Activated sludge settleability was determined by the settlometer test.
The results are presented in Figure 2. The top three curves represent settling
characteristics of well mixed samples from the contact basin. These samples
exhibited slower than optimum settling but the supernatant was extremely clear.
The bottom curve (July 27) exhibited settling characteristics different from
other tests, the cause of which was uncertain. On July 28, a settlometer test
was run on a sample collected 5 minutes after the aerator shut off. Settling
similar to the July 27 curve was observed. These two samples settled much faster
and left an extremely turbid supernatant. Further testing will be necessary to
firmly establish a trend. However, these data indicate that a portion of the
suspended solids settle out when the aerator shuts off. The remaining solids
vMch flow out of the contact basin exhibit a drastically different settling
characteristic.
Microscopic examination of return kludge and foam showed an extensive
population of filamentous organisms, which typically exhibit the observed
settling characteristics. Observations of the activated sludge and large quantities
of foam on the aeration basins and clarifiers indicate an old sludge and/or
excessive grease which coupled with low DO concentrations would favor filamentous
growths. Observation of the protozoan population indicated that the elimination
of the filaments would result in a good low BOD, low suspended solids effluent.
The mixed liquor contained a diverse population of protozoans which included
ciliates of all types (free swirrrning, crawling, stalked) rotifers and a small
population of flagellates. A mixed community of these organisms indicate a
treatment system attempting to recover from a stress condition. Increasing
sludge wasting and DO in the aeration basins should reduce the sludge age and
provide an environment for growth of more favorable micro-organisms.
Activated sludge quality was further determined by measuring the oxygen
uptake rate of the sludge by the procedure presented in Appendix E. The sludge
activity may be measured by mixing return activated sludge with influent (fed)
and nan chlorinated effluent (unfed) wastewater and determining the uptake rate.
The load ratio (LR) may be calculated by equation 1.
LR = ATO(m&/l/min) fed sludge
AD0(ittg/l/min) unfed sludge (1)
9
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FIGURE 2 .
Activated Sludge Settleability
lOOS^
_ July 26
& & July 27
o—o July 28
* July 28
July 28
25 30
TIME (M1N)
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Assuming a 50 percent return sludge flow, the LR was determined to be
1.7. A small LR (<2) may indicate dilute feed, sick sludge, poorly acceptable
feed, or other unfavorable conditions (12). These results corroborate earlier
observations of old excessive sludge and low D.O.
CLARIFIERS
The major problems with the clarifiers were solids carryover and excessive
foam and scum. The entire clarifier surface was covered with foam. Foam and
scum were collected in troughs and returned to the head of the plant. Measured
and recommended operating parameters for secondary clarifiers following the
contact stabilization activated sludge process are presented in Table IV.
TABLE IV
SECONDARY CLARIFIER OPERATIONAL PARAMETERS
Hydraulic Loading
(gpd/sq. ft.)
Solids Loading
(lbs/day/sq.ft.)
Hydraulic Detention (hrs)
#1
#2
#3
#4
Weir Overflow Rate
(gpd/lin.ft.)
* - Calculated as volume/flow
+ - Measured by dye
Several clarifier hydraulic properties were investigated losing a fluorescent
dye. The hydraulic detention times measured by the dye were significantly less
than the calculated values. Dye peaks were observed about 30 minutes after dye
addition which indicate short-circuiting. Further results of the dye study are
presented in Figure 3. These data show that clarifier #1 received the major
portion of flow. The operator attempted to equalize flows to the four clarifiers
by changing influent gate openings during the day as flows varied. Solids were
often observed flawing over the weirs of individual basins as flows to the basins
became unbalanced. Also solids were lost in the effluent during evening high
flow periods when the WTP was not manned.
There was no means to measure the return sludge flow (RSF). No sludge
blanket was observed during the study period indicating an excessive RSF.
The effluent varied from extremely good to poor, depending whether or
not solids were washing out. The average effluent turbidity was 3 NTU, except
for a single sample, indicating excellent treatment. At times, based on
observations, the turbidity reached 120 or greater showing the difficulty of
holding solids in the clarifiers.
MEASURED RECOMMENDED (3)(4)(7)
335 400 - 800
11 20 - 30
4.3* 2.5
1.4+
1.4+
1.4+
1.7+
4,610 <15,000
11
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FIGURE 3
Clarifier Dye Study
Main WTP
Mt. Pleasant, S.C.
200 300 400
TIME (MIN)
% of Flow
600
12
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Significant quantities of grit collected daily in the influent channel
to the final clarifiers. Daily deposition altered flows to the individual
clarifiers. This condition further complicated the problem of balancing
clarifier flows.
CHLDRINATION
Effluent from the final clarifiers was disinfected in the chlorine contact
chamber (CCC) prior to discharge into the Intracoastal Waterway. The hydraulic
detention time was about 35 minutes at a flow of 0.83 mgd. Chlorine was added
at the average rate of 35 pounds/day. The average total chlorine residual was 3.3
mg/1 and ranged from 2.6 to 4.2 mg/1, based on the amperorretric back titration
method. During the same period, WTP personnel measured chlorine residuals of
about 1.5 mg/1 based on the orthotolidine color cornparater. Use of the
amperometric back titration method could reduce chlorine usage resulting in a
substantial monetary savings.
AEROBIC DIGESTER
Waste activated sludge was conditioned in the aerobic digester. Dissolved
oxygen in the basin was greater than 5 mg/1 (Appendix B). The TSS and VSS
concentrations were 9,688 and 6,000 mg/1, respectively. The volatile content
was 62 percent.
LABORATORY
The laboratory was located in the main control building at the Mt.
Pleasant WTP. Laboratory personnel collect samples and conduct routine analyses
for the Main WTP and three other WTPs. These routine analyses include EOD5, DO,
pH, temperature, settleable solids, TSS, TS, fecal coliform, and residual
chlorine. In addition, laboratory personnel conduct control tests on the Mt.
Pleasant WTP.
While at the Mt. Pleasant WIP various analytical procedures were discussed,
however, the following observations were specifically noted:
1. BOD5 test: (1) effluent samples collected after chlorination were not
seeded or dechlormated. The lack of seeding and dechlorinating on
chlorinated samples may lead to erroneously low BOD5 results; (2) calcu-
lations were made on samples with DO depletions outside the recommended
range of 40 to 70 percent (8).
2. The orthotolidine method was used to determine residual chlorine in
the plant effluent. The determination of residual chlorine in samples
containing organic matter presents special problems, therefore Standard
Methods (8) recommends a back titration method for determining residual
chlorine in wastewater.
3. TSS samples were dried in an oven set on a temperature of 112° C.
Standard Methods recotimends drying TSS samples at 103°-105° C for at least
1 hour or untilthe samples reach constant weight.
13
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A quality control (OC) program is desirable in all laboratories. A
good QC program would include setting up duplicates on approximately 20 percent
of the samples, and analyzing standards, if available, approximately 10 percent
of the time. This would help the analyst in determining the precision and accuracy
of his data.
The Mt. Pleasant in-plant control testing program included aeration basin
TSS, TS, SVI, SDI, and DO (surface); and aerobic digester TSS and TS. It was
suggested that the following tests be included in their program: (1) settlometer
in place of the graduated cylinder since the settlometer better represents
clarifier conditions; (2) clarifier sludge blanket depth; (3) aeration basin DO
at various depths; (4) aeration basin and return sludge VSS; and (5) centrifuge.
The centrifuge test gives a quick indication of the solids content in the
aeration basin. It was further suggested that trend charts be established and
maintained. Useful parameters for plotting include MLSS, sludge settleability,
significant influent and effluent waste characteristics, flow, depth of clarifier
sludge blanket, and F/M. Experience will dictate which of these parameters are
necessary for successful plant operations. These suggested parameters should
serve only as a guide and are intended to establish trends so that gradual
changes in plant conditions can be noticed prior to deterioration in effluent
quality.
14
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1
2
3
4.
5
6
7
8
9
10
11
12
13
14
REFERENCES
McKinnery, Ross E. and Gram, Andrew. "Protozoa and Activated Sludge"
Sewage and Industrial Waste 28 (1956): 1219-1231 '
US-EPA, Operation of Wastewater Treatment Plants, A Field Study Training
Program, Technical Training Grant No-SlTl^lP-I^OS.
US-EPA Technology Transfer, Process Design Manual for Suspended Sol-id* Wn
January 1975. —1
American Society of Civil Engineers, Sewage Treatment Plant Design Manual
of Engineering Practice No. 36, 1959.
Metcalf and Eddy, Inc., Wastewater Engineering, 1972
West, Alfred W., Operational Control Procedures for the Activated Sludge
Process. Part I., Observations, KPA-330/9-/4-uni-aJ April IQ73
Great Lakes - Upper Mississippi River Board of State Sanitary Engineers
Recontnended Standards for Sewage Works. Revised Edition, 1971.
American Public Health Association, Standard Methods for the Examination of
Water and Wastewater, 13th Edition, 1971. ~—
US-EPA Technology Transfer, Process design Manual for Upgrading Existing
Wastewater Treatment Plants, October 1974.
Black and Veatch, Estimating Costs and Manpower Requirements for Conventional
Wastewater Treatment Facilities, October 1971.
Homer W. Parker, Wastewater Systems Engineering. 1975.
From Script for slide tape XI-43 "Dissolved Oxygen Analysis - Activated
Sludge Control Testing", prepared by F.J. Ludzack, NWTL, Cincinnati.
Alfred W. West Operational Control Procedures for t-hP
Process, Appendix, March 1974. " c—
Steel, E.W., Water Supply and Sewerage. Fourth Edition, I960.
15
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APPENDIX A
LABORATORY DATA
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APPENDIX A
LABORATORY DATA
MT. PLEASANT .MAIN WTP
-------
APFES'DIX A
LABORATORY -D
MTPLEASANT MAIS WTP
CHARLESTON, S. C-.
CLARIFIERS
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APPE>iDIX A
. LABORATORY'DATA .
MT. PLEASANT MAIM WTP
CHARLESTON, g'.' C.
CONTACT ASP REAERATIOK BASINS, RETURN SLUDGE, AND AEROBIC DIGESTER
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APPENDIX B
DISSOLVED OXYGEN DATA
-------
APPENDIX B
DISSOLVED OXYGEN DATA
STATION
A
A
B
B
B
B
B
C
D
MI
A
B
C
C
C
© C#
Re-Aeration
® B-
Digester
©
•d
COMMENTS
Contact
©
•A
DATE
JULY '77
TEMP
°C
DO (mg/1)
1 ft.
DO (mg/1)
5 ft.
26
29
1.0
1.1
#1 Aerator on
26
29
0.1
0.15
#1 Aerator off
26
27
0.15
0.4
#2 Aerator on
26
0.3
#2 Aerator on
26
0.2
#2 Aerator off
26
0.15
#2 Aerator off
26
0.1
#2 Aerator off
26
27
0.5
0.7
#3 Aerator off
26
26
5.5
6.1
#4 Aerator on
0.3
Plant influent
27
28
1.5
1.3
#1 Aerator on
27
27
0.3
0.6
#2 Aerator off
27
27
1.4
#3 Aerator on
27
27
0.4
#3 Aerator off
27
27
0.15
#3 Aerator off
nin.
mill,
min.
mill,
min.
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APPENDIX C
GENERAL STUDY METHODS
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APPENDIX C
GENERAL STUDY METHODS
Methods used to accomplish the stated objectives included extensive
sampling, physical measurements and daily observations. ISCO model 1392-X
automatic samplers were installed on the influent and final effluent wastewater
streams. Samples were collected for three consecutive 24-hour periods. 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. An influent grab sample for oil and grease was collected.
All flows were measured from plant recorders and totalizers. All
dissolved oxygen measurements were determined losing the YSI model 57 dissolved
oxygen meter. Temperatures and pH were measured at various stations throughout
the WTP with a thermometer and portable pH meter. Depth of the secondary
clarifier sludge blankets were determined daily using equipment suggested by
Alfred W. West, EPA, Cincinnati (13). Sludge activity was determined by the
oxygen uptake procedure presented in Appendix E.
A series of standard operational control tests were run daily:
(1) Settleability of mixed liquor suspended solids (MLSS) as determined
by the settlometer test;
(2) Percent solids of the mixed liquor and return sludge determined by
centrifuge;
(3) Suspended solids and volatile suspended solids analysis on the
aeration basin mixed liquor and return sludge and
(4) Turbidity of each final clarifier effluent.
Daily effluent total chlorine residual concentrations were determined
using an anperometric titrator (Fischer and Porter Model 1771010).
The procedure for the BOD5 determination deviated from Standard Methods
(8). Samples were set up and returned to Athens, Georgia in an incubator vfoere
the analyses were completed.
Visual observations of individual unit processes were recorded.
Mention of trade names or commercial products does not constitute
endorsement of recomnendation for use by the Environmental Protection Agency.
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APPENDIX D
PROJECT PERSONNEL
-------
Charles Sweatt
Ronald Barrow
Herb Barden
Lavon RevelIs
Tom Sack
Eddie Shollenberger
Richard Rehm
Bill Cosgrove
APPENDIX D
PROJECT PERSONNEL
Sanitary Engineer
Sanitary Engineer
Microbiologist
Chemist
Technician
Technician
Student Trainee
Student Trainee
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APPENDIX E
OXYGEN UPTAKE PROCEDURE
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APPENDIX E
OXYGEN UPTAKE PROCEDURE 1/
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)
7. 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 BOD bottle is:
300 X .4 _ 120 Q, -
1.0 + ;4 ~ Of = 86 ml
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 while transferring
the contents. Re-invert and shake again while returning the sample to
the original test bottle. The sample should now be well mixed and have
a high DO.
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 Htttp t=). Read and record
the DO again at 1 minute intervals until at least three consistent
readings for the change in DO per minute are obtained (ADO/min). Check
for the final sample temperature. This approximates sludge activity in
terms of oxygen use after stabilization of the sludge during aeration
(unfed sludge activity).
7. Repeat steps 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.
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APPENDIX (Continued)
The load factor (LF), a derived figure, is helpful in evaluating sludge
activity. It is calculated by dividing the DO/irrm 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 large factor means abundant,
acceptable feed under favorable 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.
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