epa 9^/9-77-019
TECHNICAL ASSISTANCE PROJECT
AT THE
LANETT WASTEWATER TREATMENT PIM
LANETT, ALABAMA
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ENVIRONMENTAL PROTECTION AGENCY
REGION IV
SURVEILLANCE AND ANALYSIS DIVISION
ATHENS, GEORGIA
FEBRUARY 1977
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TECHNICAL ASSISTANCE PROJECT
AT THE
LANETT WASTEWATER TREATMENT PLANT
LANETT, ALABAMA
Environmental Protection Agency
Region IV
Surveillance and Analysis Division
Athens , Georgia
February 1977
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TABLE OF CONTENTS
Introduction 1
Summary 3
Recommendations 5
Treatment Facility 6
Treatment Processes 6
Personnel 10
Study Results and Observations 11
Flow 11
Waste Characteristics and Removal Efficiencies 11
Aeration Basin 14
Clarifiers 20
Chlorine Contact Chamber 22
Sludge Handling 24
Laboratory 25
References 29
Appendices
A. Laboratory Data
B. General Study Methods
C. Activated Sludge Formula Used for General Calculations
D. Dissolved Oxygen Data
I?. Oxygen Uptake Procedure
F. Project Personnel
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Figures
1. LaneCt WTP 7
2. Stabilization Curve February 15, 1977 - Lanett WTP 18
3. Stabilization Curve February 16, 1977 - Lanett WTP .... 1.9
4. Average Aeration Basin Settlometer Result - Lanett WTP . . 21
5. Clarifier Dye Study - lanett WTP 23
Tables
I. Design Data - Lanett WTP 8
IT. Waste Characteristic and Removal Efficiencies - Lanett OTP.12
Til. Lanett WTP 20-Day BOD 14
IV. Activated Sludge Operational Parameters - Lanett WTP. . . .15
V. Oxygen Uptake Rates - Lanett WTP 16
VI. Secondary Clarifier Operational Parameters - Lanett WTP . .22
VII. Results of Chemical Analyses on Split Samples 28
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INTRODUCTION
A technical assistance study of operation and m.-ii nten/inre problems
at the Lanett Wastewater Treatment Plant (WTP) , l.anett, Al.abama was conducted
February 14-18, 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 US-EPA Enforce-
ment and Water Divisions because of the high influent and effluent pH
(>9.0) and a proposal to discharge excess solids into the Chattahoochee River.
It was proposed that by generating new solids better treatment and solids
separation could be attained.
The specific study objectives were:
1. To optimize treatment through control testing and recommended
operation and maintenance modifications;
2. To Lntroducc and instruct personnel in new operational control
tec hniq ues;
3. To determine influent and effluent wastewater characteristics;
4. To assist laboratory personnel with any possible laboratory
procedure problems; and
5. To compare design and current loading rates.
A follow-up assessment of the plant operation and maintenance practices
will be conducted at a later date. This will be accomplished through
utilization of data generated by plant personnel. If necessary, subsequent
visits to the Facility will be made. The follow-up assessment will determine
if recommendations were successful in improving plant operations and if
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Further assistance Ls required.
The technical assistance team is appreciative for the cooperation
and assistance received from personnel of the Lanett WTP. The
cooperation of Mr. Clint Constant (Engineering Consultant)Is also
gratefully acknowledged.
2
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SUMMARY
The Lanett Wastewater Treatment Plant (WTP) was constructed as a
5 mgd extended air activated sludge system and began operation in
October, 1974. A population of approximately 7,000 are served with roughly
60 percent of the influent plant flow from industrial sources, primarily
Lwo West Point Pepperell Textile Mills. The flow during the study period
averaged 2.82 mgd and ranged from 1.32 to 3.20 mgd. Treatment was excellent
with a 98 percent reduction in BOD5 and an 81 percent reduction in TSS.
This produced an effluent with an average BOD^ of 12 mg/1 and an average TSS
concentration of 17 mg/1. Listed below are some observations made during
the study.
1. The facility was well maintained and was achieving high waste
treatment efficiencies in spite of the extremely high industrial
influent pH levels (11.5-12.0 pH units). When the caustic recovery
unit at the West Point Pepperell Plant goes on line (estimated for
Oct. 77) a considerable reduction in wastewater pH should occur.
Stabilization tests indicated that neutralization or pH adjustment
would permit the biological stabilization process to proceed at
a faster rate, however in this case since excessive detention time
is available pH adjustment would not be expected to improve
treatment efficiencies.
2. No evidence was found to support the idea of dumping the WTP's
solids in order to get rid of the finely suspended solids and
build up a better settling sludge.
3
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3. Chromium concentrations in the plant's combined influent and
aerobic digester were 13.64 and 762 mg/1., respectively.
4. The industrial influent and return sludge flow measuring devices
were out of calibration as determined by instantaneous flow measure-
ments .
5. Dye studies indicated an imbalance of flow to the two clarifiers.
6. Solids separation in the aerobic digester was difficult to
achieve because of poor solids settleability.
7. Because of a slow dewatering sludge, drying beds were tied-up
for long periods of time.
8. During the study, chlorine was applied to the chlorine contact
chamber at an average rate of 140 lbs/day which produced a
chlorine residual in the effluent of 1.25 mg/1.
9. The laboratory was well equipped. Adequate records were being
maintained, and one of the EPA control tests (settlometer) had
been implemented prior to the study.
L0. The average percent difference in split sample results between EPA
and Lanett WTP for BOD5, TS, TVS, TSS, and VSS was greater than
Standard Method's precision data for the same test.
4
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RECOMMENDATIONS
Rased on observations and data collected during the study, It
Ls recommended that the folLowing measures be taken to Lmprove wastewater
treatment and plant operation. Trend charts and operational testing will
assist in determining optimum control.
1. No evidence was found to support the idea of dumping the aeration
basin contents in order to get rid of the finely suspended solids
and build a better settling sludge. A better course of action
would be to gradually increase the sludge wasting rate which would
decrease the MLSS concentration and increase the F/M ratio. This
should produce a better settling sludge with fewer finely suspended
particles.
2. All flow measuring devices should be checked and calibrated
periodically.
3. The cause for the difference in the hydraulic detention times between
the two final clarifiers should be determined and corrected.
A. In the BOD^ test the following procedures should be followed:
(1) Samples should be neutralized and dechlorinated before analysis,
(2) Those samples with DO depletions between 40 and 70 percent
should be used in the BOD5 calculations, and
(3) The Standard Method's procedure for calculating the seed
correction factor should be used.
5. In the solid analysis, oven treated samples should be allowed to
reach room temperature before weighing.
6. Standard Method's back titration method should be used in determining
chlorine residual in wastewater.
5
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TREATMENT FACILITY
TREATMENT PROCESSES
A schematic diagram of the 5 mgd, Lanett Wastewater Treatment Plant
(WTP) is presented in Figure 1, and design data are enumerated in Table I.
The extended air activated sludge facility which began operation in
October, 1974 serves a population of approximately 7,000 persons. Roughly
60 percent of the plant influent flow was industrial, primarily from two
West Point Pepperell Textile Mills (Lanett Bleachery and Dye Works and
Lanett Mill). Wastewater from the Lanett Bleachery and Dye Works was
comprised of sanitary wastewater and industrial process wastewater. The
discharge from the Lanett Mill was also comprised of sanitary wastewater
and industrial process wastewater.
The municipal and industrial wastewaters entered the plant through
two separate lines and were mixed with return sludge in a mixing well at
the head of the aeration basin. The municipal wastewater influent was
measured with a nine inch Parshall flume, recorder and totalizer before passing
through a comminutor and being pumped into the mixing well. The industrial
wastewater influent was measured with a 12-inch Parshall flume, recorder
and totalizer after which it was pumped through lint screens into the
mixing well. The industrial wastewater stream was monitored for pH following
the lint screens.
The combined wastewater flowed into the aeration basin which was
equipped with nine 100 hp fixed mechanical aerators. These aerators were
operated on a twelve hour cycle with 5 on and h off on one cycle and four on
and five off the next twelve hours. Effluent from the basin was split as it
flowed to the two final clarifiers. The effluent was chlorinated before
6
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FIGURE I
LANETT WASTEWATER TREATMENT PLANT
LANETT, ALABAMA Drying Beds
LAD
Thi^kner
Supernatant
Industrie
Influent Parshal I
Flume
To
Chattahoochee
River
ators
Grit Chamber
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TYPE
Design Flow
Flow (study average)
FLOW MEASUREMENT
Influent (municipal)
Influent (industrial)
Return Sludge
Waste Sludge
F.ff luent
AERATION BASIN
Number & Type
Length
Width
Depth
Area
Volume
Detention Time
Aeration
CLARIFIERS
Number & Type
Diameter
Depth (SWD)
Surface Area (each)
Volume (each)
Wc.lr Length (each)
DIGESTER
Number & Type
Length
Width
Depth
Volume
Aeration
CHLORINE CONTACT CHAMBER
Number & Type
Length
Width
Volume
Detention Time (design)
TABLE I
DESIGN DATA
LANETT WTP
LANETT, ALABAMA
EXTENDED AIR
5.00 mgd
2.82 mgd
9 in. Parshall Flume, Recorder, Totalizer
12 in. Parshall Flume, Recorder, Totalizer
6 in. Parshall Flume, Recorder, Totalizer
6 in. Parshall Flume, Recorder, Totalizer
3 ft. Parshall Flume, Recorder, Totalizer
1 - Trapezodial
610 ft.
300 ft.
17 ft.
183,000 sq. ft.
2,314,975 cu. ft. (17,300,000 gals)
3.5 days
9- 100 hp fixed mechanical aerators
2 - Circular
75 ft.
10 ft.
4,418 sq. ft.
44,179 cu. ft
236 ft.
(330,459 gals)
1. - Aerobic
240 ft.
115 ft.
17 ft.
357,459 cu. ft. (2,674,00 gals.)
3 - 75 hp fixed mechanical aerators
1 - Rectangular
35.3 ft.
31.8 ft.
16,868 cu. ft. (126,175 gals)
36 min.
8
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TABLE T (cont)
DRYINC KEDS
Number & Type
Length
Width
Volume (each)
12 - Rectangular
60 l~t.
50 ft.
3,000 cu. ft. (22,400 gals.)
<)
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discharge into the Chattahoochee River (which has a fish and wildlife
stream classification). The plant effluent flow was measured with a
three-foot Parshall flume equipped with a totalizer and recorder.
Return sludge was pumped through a splitter box into the mixing well
at the head of the aeration basin, and the waste sludge flowed to the
aerobic digester. The return sludge flow was measured with a 6-inch
Parshall flume, equipped with totalizer and recorder, and the waste sludge
flow was measured with a 6-inch Parshall flume equipped with totalizer
and recorder. The aerobic digester was equipped with three fixed aerators.
After digestion the sludge flowed to the sludge thickener and was then
pumped back to the aerobic digester. The treated sludge was withdrawn from
the aerobic digester to twelve drying beds where it was dried and disposed
of in a land fill. The sludge thickener supernatant was returned to the
head of the plant.
PERSONNEL
The Lanett WTP was staffed by one plant supervisor, four operators,
nnd laboratory technician. Only the plant supervisor was certified (grade 3).
The remaining personnel were attending certification classes. The WTP
has a full time engineering consultant. Also West Point Pepperell personnel
assisted in maintenance and repair operations as needed.
10
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STUDY RESULTS AND OBSERVATIONS
A complete listing of all analytical data and general study methods
are presented in Appendices A thru E. Significant results and observations
made during the study are discussed in the following sections.
FLOW
During the study, the combined plant flow averaged 2.82 mgd (Table I),
and ranged from 1.32 to 3.20 mgd. Of the average combined plant flow the
city contributed 1.13 mgd (40 percent) and the industries contributed 1.69
mgd (60 percent).
The average return sludge flow during the study was 1.95 mgd which
was approximately 69 percent of the combined plant flow. A total of 0.24
million gallons of sludge was wasted to the aerobic digester during February
17 and 18.
Instantaneous flow measurements were made to determine the accuracy of
each flow measuring device. The industrial influent recorder and instantaneous
flows were 1.65 and 1.91 mgd, respectively. Adjustment and calibration of
the flow recording equipment were recommended.
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
A chemical description of the Lanett WTP influent and effluent
wastewaters with calculated treatment reductions are presented in Table II.
Analyses were conducted on 24-hour, flow proportional composite samples,
collected on three consecutive days during the study period. Each influent
stream (industrial and domestic) was analyzed and the results were added
together proportional to the respective influent flow. The averages of these
results were used to calculate the percent reductions during the study
period.
II
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The average composite influent BOD5 (750 rag/1), COD (l,498mg/l), TOC
(508 mg/1), and Cr (13.64 mg/1) concentrations are representative of a
strong waste. The TSS (91 mg/1) average concentration was low as compared
to typical domestic waste (5).
The average effluent BOD5 ant* concentrations were 12.5 and 17 mg/1
representing reductions of 98 and 81 percent, respectively. These
concentrations were within the required NPDES BOD5 and TSS monthly average
permit limitation of 60 mg/1.
As shown in table II, TKN-N and NO3-NO2-N concentrations were reduced
within the wastewater treatment process by 57 and >83 percent, respectively,
while NH3-N was increased by 28 percent. The organic-N in the plant
influent was probably converted to NH3-N. Since the pH in the aeration basin
was high (>9.5), most of the converted and influent NH3-N was air stripped
from the system. The NO3-NO2--N was assimilated by the mixed liquor biomass.
TABLE II
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
LANETT WTP
INFLUENT
EFFLUENT
REDUCTION
PARAMETER
(mg/1)
(mg/1)
(%)
BOD5
750
12.5
98
COD
1498
182
88
TOC
508
63
88
TS
2594
2026
22
TVS
834
270
68
TSS
91
17
81
VSS
72
10
86
TKN-N
15
6.5
57
NH3-N
2.42
3.1
-28
NO3-NO2-N
0.64
<0.11
>83
TOTAL PHOSPHORUS
4.9
2.9
41
Pb
<0.05
<0.05
—
Cr
13.64
2.82
79
Cd
<0.01
<0.01
—
Cu
0.097
0.043
56
Zn
2.29
0.194
92
Ni
<0.05
<0.05
—
12
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Table III presents the 20 day BOD data for the Lanett WTP influent
and effluent. Analyses were conducted on 24-hour, flow proportional,
composite samples, collected on February 15 through 16, and February
16 through 17, 1977. The influent BOD20 values for the two day period were
1,400 and 2,000 mg/1, and the effluent BOD20 values were 62 and 40 mg/1,
respectively. The effluent BOD5 values for the same samples (6.6 and 14.6
mg/1) represent 11 and 36 percent, respectively, of the B0D2Q- It is
interesting to note that the oxygen consumption rate increases significantly
after 15 days. On the effluent samples the process appears to proceed at
an increasing rate. One would suspect nitrification, however there was not
sufficient nitrogen in the samples (Appendix A). The phenomenon was probably
due to an extended acclimation period or to some organic compound or
compounds being broken down to a biologically usable state.
The combined influent ratio of BOD5 to nitrogen to phosphorus was
calculated at 100: 2.09: 0.65. As compared to the recommended ratio of
100: 5: 1.7, the raw waste was limited in both nitrogen and phosphorus (9).
During the study, the industrial influent pH was extremely high (11.5
to 12.0), and even after mixing with the domestic influent the pH in the
aeration basin did not drop below 9.5. During the previous eleven months,
the WTP personnel reported a minimum and maximum pH of 10.7 and 13.0.
The West Point Pepperell plant is in the process of constructing a caustic
removal system which should mitigate the high pH. This unit should be
completed by October, 1977. Tf the pH is maintained in the range of 8.0
or above, most metals, except mercury and chromates, are precipitated as
hydroxides and become incorporated in the sludge. If the pH should fall,
large amounts "of metals in the sludge could be released and cause harm to
the treatment plant and stream biota (14).
13
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TABLE ITT
I.ANETT WTP 20-DAY BOD
INOIISTRFAL INFLUENT (2/16/77) INDUSTRIAL INFLUENT (2/3 7/77)
PAY TOTAL BOD (mg/1) DAY TOTAL BOD (mg/1)
21 (hr) 260
5 1,000 5 1,086
6 1,100 6 1,144
7 1,240 8 1,286
9 1,216 11 1,467
12 1,274 14 1,500
15 1,070 20 2,000
20 1,400
WTP EFFLL'ENT (2/L6/77) WTP EFFLUENT (2/17/77)
DAY TOTAL BOD (mg/1) DAY TOTAL BOD (mg/1)
21 (hr) 0.8
5 6.6 5 14.5
6 9.0 6 16
7 14.6 8 18
9 28 11 28
12 31 14 37
15 42 20 40
20 62
AERATION liASTN
Crab samples collected at the discharge end of the aeration basin were
analyzed for total suspended solids (TSS) , volatile suspended solids (VSS) ,
percent solids by centrifuge, and settleability as determined by the settlo-
meter. Presented in Table IV are various calculated activated sludge
operational parameters for the study period and corresponding recommended
values from the literature.
The calculated loading parameters in Table IV indicate that the system
was operating within recommended loading ranges. It should be pointed out
that this system was designed with a greater than normal detention time
in order to more adequately handle the large volume of industrial waste.
14
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TABLE IV
ACTIVATED SLUDGE OPERATIONAL PARAMETERS
LANETT WTP
MEASURED RECOMMENDED (2)(5)(7)
Miss (mg/1) 2,750 3,000 - 6,000
Mlvss (mg/1) 2,070 ------
Hydraulic Detention Time, (hrs) 88 18 - 36
Mean Cell Residence Time (days) 34 20 - 30
Lbs B0D5/day/lb Mlvss (F/M) 0.06 0.05 - 0.15
Lbs COD/day/lb Mlvss 0.12 <0.20
Lbs BOD5/day/l,000 cu. ft. of
Aeration Basin 7.6 10-25
Return Sludge Rate (% of Average
Plant Flow) 69 50 - 200
Dissolved oxygen (DO) was measured throughout the aeration basin and
the results are presented In Appendix D. These data show an abundance
of oxygen at each sampling station at each depth tested from one to fifteen
feet (except at station 2). DO concentrations at Station 2 were less than
0.2 mg/1 at depths greater than 10 feet from the surface. The reason for
this low DO was that aerator #2 was off at the time of sampling and sludge
had settled in that corner of the basin.
Sludge activity is a valuable indicator of sludge quality. Two
methods of determining sludge activity are oxygen uptake rates and
microscopic examinations. The oxygen uptake rate or load ratio is the measure
of oxygen depletion before and after the introduction of raw waste.
Load ratio = DO/min. fed sludge
DO/min. unfed sludge
The oxygen uptake procedure is presented in Appendix E. Calculated
load ratios arc listed in Table V. The unfed sludge data indicate that the
sludge was rather inactive and over-oxidized. Generally a fed sludge oxygen
uptake rate should be 1.0 mg/l/min. or greater (12). Data during this
study show that the fed oxygen uptake rates ranged from 0.2 mg/l/min to 0.6
mg/l/min. In relation to the unfed sludge, the increased uptake rates of the
15
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TAHLE V
OXYGEN UPTAKE RATES
l.ANKTT, OTP
AVERAGE Q? UPTAKE
RS I'RS (mg/l/min) FRSq* lmg/l/min) FRS 30*tmg/l/min) LRn LR^n
DATE TIME % TREATED UNTREATED TREATED UNTREATED TREATED UNTREATED TREATED UNTREATED TREATED UNTREATEI
10.0 4.0
12.0 5.6
URS - Unfed return sludge (clarifier effluent plus RS)
FRS - Fed return sludge (Raw influent plus RS)
LR - Load ratio (FRS/URS)
* Initial uptake at time zero (oxygen uptake rate)
** Uptake after 30 minutes aeration time (stabilization test)
2/15/77 1100 63 .05 .05 0.30 0.30 0.5 0.2 6.0 6.0
2/16/77 1105 63 .05 .05 0.32 0.40 0.6 0.28 8.0 6.4
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fed sludge was acceptable, however both rates were much lower than normal.
This should be expected since the system is operating under adverse pH
conditions and no doubt the variety of organisms are limited when compared
to a typical domestic waste system. These tests do show that the waste is
utilized by the organisms in the system.
Indications from the stabilization results (Figures 2 and 3) are that
aeration time in the aeration basin was more than adequate. Both adjusted
(pH) and unadjusted test show that the sludge reaches the initial activity
rate (unfed ratio) within 24 to 30 hours after feeding. After 24 to 30
hours the waste had been degraded and the sludge had been stabilized, however,
the aeration basin provided approximately 58 to 64 hours of additional
detention time. Additional stabilization time will probably be required
as the loading on the plant increases to design values.
The unadjusted stabilization test (pH 9.5 - 11) showed generally a
lower activity rate than pH adjusted samples. On each test date the data
showed that within the first 60 minutes the sludge appeared to be momemtarily
shocked by the incoming waste. On February 15, 1977, the shock lasted for
four hours and the activity only increased to the initial fed sludge level
before tapering off. On the pH adjusted samples the increased activity
rate began immediately. It can be concluded from these tests that if the
incoming wastewater was neutralized the initial oxygen uptake rates would
be much higher and the stabilization period would be shorter. This,however,
is not necessary under present loading conditions.
A microscopic examination of the activated sludge, indicated that the
sludge was void of protozoan generally found in an active stabilized sludge.
Filaments were abundant, but were not concentrated enough to cause severe
settling problems. The sludge mass was lightly colored, and separated
into distinct small lobes. Observations of the aeration basin surface
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00
0.7
LU
0.6
<
h-
Q_
Z)
0.5
2
'c
0.4
LU
'e
y—
v.
X
0.3
o
E
LU
¦—
O
0.2
<
cr
UJ
0.1
>
i
<
i
FIGURE 2
STABILIZATION CURVE
LANETT WTP
FEBRUARY 15,1977
o pH Unadjusted -11.7
>pH Adjusted-7.0
SLUDGE ACTIVITY RATE
0
22 23 24
TIME (Hours)
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0.7 —
FIGURE 3
STABILIZATION CURVE
LANETT WTP
FEBRUARY 16,1977
pH Unadjusted-I 1.0
a a pH Adjusted -6.6
SLUDGE ACTIVITY RATE
_J I I I L
0
4 5 21 22 23
TIME (Hours)
24 25 26 27 28
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showed a dark mixed liquor with a thin white foam. Generally a dark
mixed liquor and a thin white foam would contradict each other, but in
this case the dark mixed liquor was caused by industrial dye waste, and the
thin white foam normally associated with a young sludge is typically
present in treated textile waste.
The settlometer results shown in Figure 4 indicate a good settling
sludge. The supernatant was a dark color and turbid. In Figure 4, the
settlometer curve of the mixed liquor diluted by 50 percent shows a rapid
fall out of solids indicating that there was no tendency toward a bulking
sludge.
SECONDARY CLARIFIERS
Both circular clarifiers had a center feed, rim take-off flow
configuration wi.th a center baffle to distribute incoming flow. The
baffle also had holes cut above the water line to facilitate distribution
of scum and floating debris toward the outer edge of the clarifiers.
Scum and floating debris were removed by a radial skimmer arm.
The measured and recommended operating parameters for secondary
clarifiers following the extended air activated sludge process are
presented in Table VI. The measured values are based on the average influent
(2.82 rngd) flow during the study period and the assumption that the flow
was equally split between the two clarifiers. Based on a comparison between
the calculated nnd recommended design criteria, both clarifiers were adequate
for the flow rate and solids loading measured during the study. Good
clarifler performance was indicated by the low average effluent turbidities
of 3 and 4 NTU for clarifier #1 and //2, respectively, and the low average
plant effluent TSS of 17 mg/1.
20
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FIGURE 4
AVERAGE AERATION BASIN SETTLOMETER RESULTS
TIME (Min.)
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TABLE VI
SECONDARY CLARIFIER OPERATIONAL PARAMETERS
LANETT WTP
CALCULATED
RECOMMENDED (4)(7)(9)
Hydraulic Loading
(gpd/sq.ft.)
319
200 - 600
Solids Loading
(Ibs/day/sq. f t.)
7.32
3.33
12 - 30
2-3
Hydraulic Detention (hrs.)
Weir Overflow Rate
(gpd/lin.ft.)
10,122
<15,000
During the study period the depth of the sludge blanket (DOB) in both
clarifiers was less than 0.8 ft. This was the result of the high average
return sludge rate of 1.95 mgd which was 69 percent of the average influent
The results of the clarifier dye tracer study are presented in Figure
5. The hydraulic detention time was determined from the centroid of the
curves for clarifiers //I and #2, and was found to be 87 and 124 minutes,
respectively. Both of these detention times were less than the calculated
(200 minutes), and the detention time for clarifier #1 was also less than
the recommended. The difference between the calculated and measured
detention times was caused by short circuiting. It is recognized that a
degree of short circuiting exist in all clarifiers, and it appears in this
case that the short circuiting was not creating any operational problems.
CH7 0RINE CONTACT CHAMBER
At the design flow of 5 mgd, the chlorine contact chamber (CCC) has
a 36 rain, detention time. At the average flow for the study of 2.82 mgd,
the detention time was 64 minutes. During the study chlorine was applied
at an average rate of 140 lbs/day. This application rate produced a final
chlorine residual of 1.25 ppm.
flow.
22
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FIGURE 5
CLARIFIER DYE STUDY
LANETT WTP
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The CCC located beneath the floor of the return sludge pumping
station. One small opening in the floor with a wall ladder gave access
to the CCC area. Because of the location, observation of the unit was
difficult and the possibility of chlorine accumulation made the area
hazardous.
SLUDGE HANDLING
In the aerobic digester aeration and mixing of the solids were
accomplished by the cycling of three 75 hp fixed mechanical aerators. Each
aerator was operated 8 out of every 24-hours. After the solids had been
digested, the aerators were shut-off, and the solids were allowed to settle.
The settled solids were pumped to the thickener, the supernatant was
decanted, and the thickened solids were returned back to the digester. The
solids were subsequently withdrawn and piped to the sludge drying beds.
The dried solids were disposed of in a landfill.
Two settIomoter te9ts were conducted on the aerobic digester. The
results nro gLvcn in Appendix A. After two hours the solids had settled
to an average of 98 percent by volume. This poor solid separation made it
difficult to thicken the solids for disposal to the sludge drying beds.
During the study, three aerobic digester samples were taken for solids
determination. These samples had an average TSS concentration of 13,183 mg/1
and ranged from 8,700 to 22,310 mg/l. This wide concentration range was
due to poor mixing in the digester which was caused by the cycling schedule
of the aerators. The solids were 76 percent volatile. The pH of the digester
contents was 8.6, and the chromium concentration was 672 mg/1. The effect
24
-------
of this high chromium concentration should be considered before disposing of
the sludge.
Dissolved oxygen concentrations ranged from 0.0 to 10.8 mg/1
throughout the digester. At the surface the DO ranged from 10.0 to 10.8
mg/1. Five feet below the surface the DO concentrations were 10.6 and 10.7
and at the ten foot depth there was no detectable DO.
LABORATORY
The Lanett WTP laboratory is located in the main control building and
is staffed by one laboratory technician who conducts the following routine
analyses: BOD5, TS, TVS, TSS, VSS, settleable solids, fecal coliform, pH
and chlorine residual. The laboratory was clean and neat and had adequate
room and equipment for the analyses performed. Adequate records were also
maintained on the analytical data.
The following observations relative to laboratory procedures were
specifically noted:
1. In the BOD5 test the following procedures were observed: (1)
effluent samples, which had a chlorine residual and a pH above 9.0,
were not being dechlorinated or neutralized prior to the BOD^
analysis. Both chlorine and high pH are toxic to the organisms
which exert a BOD^ and could cause erroneously low BOD5 results,
(2) some BOD5 calculations were made on samples with DO depletion
outside the Standard Method's (8) recommended range of 40 to 70
percent, and (3) the BOD^ seed correction factor was based on the
5 day DO depletion of the seeded dilution water blank. This
blank is not recommended for calculating the correction factor
because it is subject to erratic oxidation due to the very high
25
-------
dilution of the seed. The recommended practice, Standard Methods
(8) is to set-up a separate series of seed dilutions and selecting
those results with 40 to 70 percent oxygen depletion in 5 days to
calculate the seed correction factor.
2. The amperometric direct titration method was used in determining
chlorine residual 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. Solids samples were weighed before they reached room temperature.
This method does not allow the samples to reach constant weight
which is needed for accurate solid results.
The in-plant control testing program included aeration basin TS, TVS,
TSS, VSS, DO (surface), and settlometer; and drying bed sludge density
moisture content, and dewatering capability. It was suggested that the
following tests be included in their program: (1) clarifier sludge blanket
depth; (2) aeration basin DO at various depths; and (3) centrifuge. The
centrifuge test gives a quick indication as to the solids content in the
aeration basins and return sludge. 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 (plant, return sludge, waste sludge), depth of
clarifier sludge blanket, and MCRT. Experience will dictate which of these
parameters is necessary for successful plant operations. These suggested
parameters should serve only as a guide and are intended to establish
26
-------
trends so that gradual changes in plant conditions can be noticed prior
to deterioration in effluent quality.
Six 24-hour composite samples collected February 16 through 17, and
February 17 through 18, 1977 were split between EPA and Lanett WTP
personnel. The results of the analyses are given in Table VII. The
average percent difference between EPA and Lanett WTP results for BOD5,
TS, TVS, TSS, and VSS was 36, 17.5, 28.5, 41.6, and 84 percent, respectively.
Standard Methods gives precision data for the same tests of BOD5 (15%), TVS,
(6.5%), TSS 0.76 to 33%), and VSS, (0.76 to 33%).
27
-------
TABLE VII
RESULTS OF CHEMICAL ANALYSES ON SPLIT SAMPLES
PARAMETERS (rag/1)
3CD5 TS TVS TSS VSS
STATION 0
DATE
EPA
;.-yp -k
EPA
WTP
EPA
WTP
EPA
WTP
EPA
WTP
LI - 1
2/16-17/77
1,086
915
3,664
-
1,144
-
105
-
92
-
LI - 1
2/17-18/77
1,160
1,461
4,344
4,504
1,524
1,574
133
104
103
104
LI - 2
2/16-17/77
126
78
232
-
136
-
48
-
28
-
; t
2/17-18/77
95
82
228
318
138
190
52
102
37
102
LE
2/16-17/77
15
6
1,948
-
181
-
25
w
16
-
LE
2/17-18/77
16
6
2,214
2,008
484
268
15
14
8
14
LANETT WTP
-------
1
2
3
4
5
6
7
8
9
10
11
12
13
LA
REFERENCES
McKinney, 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-5TTl-WP-16-03, 1970.
US-EPA, Technology Transfer, Process Design Manual for Suspended
Solids Removal, January 1975.
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, EPA-330/9-74-001-a, April 1973.
Great Lakes - Upper Mississippi River Board of State Sanitary
Engineers, Recommended 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 the Activated Sludge
Process, Appendix, March .1 974.
EPA Technology Transfer, Wastewater Treatment Systems Upgrading Textile
Operations to Reduce Pollution, October 1974.
29
-------
APPENDICES
-------
APPENDIX A
LABORATORY DATA
-------
appendix a
LABORATORY DAT
"LANETT WTty LAN'ETT, ALABAMA
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-------
APPENDIX A
LABORATORY 3ATA
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CLARIFIERS
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-------
APPENDIX B
GENERAL STUDY METHODS
-------
APPENDIX B
GENERAL STUDY METHODS
LANETT WTP
Methods used to accomplish the stated objective included extensive
sampling, physical measurements and daily observations. ISCO Model 1392-X
automatic samplers were installed on the two influent streams (municipal,
industrial), and effluent stream and operated three consecutive 24-hour
periods. A]iquots 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.
Influent and return sludge flows were determined from plant totalizers.
Instantaneous flows were determined from the influent Parshall flumes.
All dissolved oxygen levels were determined using the YSI Model 57
dissolved oxygen meter.
An Analytical Measurements Model 30 WP cordless pH recorder was
installed on the industrial influent after the lint screen for a 24-hour
period. It was re-Lnstalled on the clarifier effluent to monitor pH through
the remainder of the sampling. Temperatures and pH were determined at other
st.it ions wLth thermometer and portable pH meter.
Depth of the secondary clarifier sludge blankets were determined daily
using equipment suggested by Alfred W. West, EPA, NFIC, Cincinnati.
Sludge activity was determined by the oxygen uptake procedure presented
in Appendix F. Treatability studies of the influent were also conducted.
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 Volitile Suspended Solids analysis on the
aeration basin mixed liquor and return sludge;
(4) Turbidity of each final clarifier effluent.
Daily effluent chlorine concentrations were determined using an
amperometric 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 in an incubator where the
analysis was completed.
An American Optical Fluoro-Colorimeter Model 4-7439 was used to determine
concentrations of Rhoda-raine B fluorescent dye during the clarifier flow
study.
Visual observations of individual unit processes were recorded.
Mention of trade names or commercial products does not constitute
endorsement or recommendation for use by the Environmental Protection Agency.
-------
APPENDIX C
ACTIVATED SLUDGE FORMULAE USED FOR
GENERAL CALCULATIONS
-------
APPENDIX C
Activated Sludge
Formulae Used for General Calculations
1 . lbs. of solids in aeration basin
Basin volume = m.g.; MLSS (conc.) = mg/1
(MLSS conc.) x (Basin vol.) x 8.34 - lbs. of solids
2. Aeration basin loading (lbs. BOD or COD/day)
Inf. flow to aeration basin = mgd
Inf. BOD or COD=mg/l
(BOD or COD) x flow x 8.34 = lbs. BOD of COD/day
3. Sludge Age (days)
MLSS conc. (avg. of dpily 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
4. Sludge Vol. Indix (SVI)
30 min. settleable solids (avg. of daily values) = %
MLSS conc. = mg/1
(%, 3 0 min. set, solids) x (10,000)
MLSS
5. Sludge Density Index (SDI)
SVT Value 100
SVI
6. Detention time (hours)
Volume of basins = gal.
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. BOD5 conc. (avg. or daily value) = mg/1
Basins Inf. COD conc. (avg. or daily value) = mg/1
Plant Flow = mgd
M1.VS S conc. (avg. or daily value, note Volatile SS) = mg/1
Basin Vol. = m.g.
(BODt; conc.)x (plant flow) x (8.34) = lbs. BOD/lb. MLVSS
(MLVSS) x (Basin Vol.) x 8.34
-------
(COD conc.) x (plant flow) x (8.34
(MLVSS) x (Basin Vol.) x (8.34) " lbs' COD/lb. MLVSS
8. Mean cell residence time (MCRT) = days
MLSS conc, (avg. or daily value) = mg/1
Basin vol. = m.g.
Clarifier vol. = m.g.
Waste activated sludge conc. = 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
(Waste activated sludge conc.) x (waste flow) x 8.34 + " ^
(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.
(clarifier Vol. (each) x 24 _ hours
Plant flow + Return Sludge Flow
2. Surface loading rate = gal./day/sq . ft.
Surface area/clarifier = sq. ft.
Plant flow to clarifier = gal./day
Plant flow to clarifier . . . .
Clarifier surface area " gal./day/sq.ft.
3. Weir Overflow Rate (ga1./day/1 in.ft.)
Weir Lenght = ft.
Plant flow to clarifier = gal./day
Plant—flow .. = gal ./day/lin. f t.
Weir length
-------
APPENDIX D
DISSOLVED OXYGEN DATA
-------
AT
1
2
3
4
5
6
7
8
9
10
APPENDIX D
LANETT WTP
DISSOLVED OXYGEN CONCENTRATIONS
S r
3 I
rj
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U
K
3
T3
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4J
c
0)
3
C
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cd
a
•H
O
iH
C
3
Aeration Basin
i
I
O:
a
O'
TEMPERATURE
DO-mg/1 DO-mg/1
DO-mg/1
DO-mg/1
DATE
CENT.
1 ft.
5 ft.
10 ft.
15 ft.
2/15/77
14°
5.2
5.0
5.0
-
2/15/77
15°
4.4
4.2
0.1
0.0
2/15/77
14°
4.1
4.0
4.0
—
2/15/77
14°
7.0
6.9
6.7
-
2/15/77
-
4.1
3.6
3.5
3.5
2/15/77
14°
7.5
7.2
7.3
—
2/15/77
15
4.4
4.5
4.4
4.3
2/15/77
14°
7.0
6.9
6.9
6.8
2/15/77
14.5
6,0
5.4
.5.7
5.6
2/15/77
14.5
6.2
6.3
—
—
Mechanical Aerator
Mechanical Aerator
(operating)
(not operating)
-------
APPENDIX E
OXYGEN UPTAKE PROCEDURE
-------
APPENDIX E
OXYGEN UPTAKE PROCEDURE ^
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
Procedure
1. Collect samples of return sludge, aerator influent and final
clarifier overflow. Aerate the return sludge sample promptly.
2. MLx the return sludge and measure that quantity for addition to
n 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 _
1.0 + . 4 - 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
fonccntratlon.
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
-------
APPENDIX (Continued)
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 time(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.
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 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".
-------
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.
-------
APPENDIX F
PROJECT PERSONNEL
-------
APPENDIX F
PROJECT PERSONNEL
Charles Sweatt
Lavon Revells
Tom Sack
Eddie Shollenberger
Carolyn Stroup
Sanitary Engineer
Chemist
Technician
Technician
Co-op
------- |