TECHNICAL ASSISTANCE PROJECT
AT 111?:
LENOIR WASl'KvJAi'Elv TilKATMEi'sT PLANTS
LENOIR, NORTH CAROLINA
SEPTEMBER 1976
ENVIRANM2HTAL PROIE^TION AGENCY
REGION L\T
SURVEILLANCE AND ANALYSIS DIVISION
ATHENS, CiiOUGIA
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TECHNICAL ASSISTANCE PROJECT
AT THE
LENOIR WASTEWATER TREATMENT PLANTS
LENOIR, NORTH CAROLINA
SEPTEMBER 1976
ENVIRONMENTAL PROTECTION AGENCY
REGION IV
SURVEILLANCE AND ANALYSIS DIVISION
ATHENS, GEORGIA
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TABLE OF CONTENTS
Title
Page No.
Introduction 1
Summary 3
Recommendations 6
Lower Creek Wastewater Treatment Plant 7
Treatment Facility 7
Treatment Processes 7
Personnel 7
Study Results and Observations 7
Flow 7
Waste Characteristics and Removal Efficiencies .... 11
Aeration Basins 14
Clarifiers 15
Chlorine Contact Chamber 17
Gun Powder Creek Wastewater Plant . 18
Treatment Facility 18
Treatment Processes 18
Personnel 21
Study Results and Observations 21
Waste Characteristics and Removal Efficiencies .... 21
Flow
21
Aeration Basins
22
Laboratory
23
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TABLE OF CONTENTS (Cont.)
Title Page No.
References 25
Appendices
A. Laboratory Data
B. General Study Methods
C. Aeration Basin Dissolved Oxygen Concentrations
Lower Creek WTP
D. Oxygen Uptake Procedure
E. Project Personnel
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LIST OF TABLES
Table No. Title Page No.
I Design Data - Lower Creek WTP 9
II Waste Characteristics and Removal
Efficiencies - Lower Creek WTP 11
III Activated Sludge Operational
Parameters - Lower Creek WTP 14
IV Secondary Clarifier Operational
Parameters - Lower Creek WTP 16
V Design Data - Gun Powder Creek WTP 20
VI Waste Characteristics and Removal
Efficiencies - Gun Powder Creek WTP 22
LIST OF FIGURES
Figure No. Title Page No.
1. Lower Creek WTP 8
2. Influent pH - Lower Creek WTP 13
3. Gun Powder Creek WTP 19
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INTRODUCTION
A technical assistance study of operation and maintenance problems
at the Lower Creek, and Gun Powder Creek wastewater treatment plants,
Lenoir, North Carolina, was conducted September 20-24, 1976, by the Region
IV Surveillance and Analysis Division, U.S. Environmental Protection
Agency. Operation 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.
These plants were selected based upon the recommendation of the U.S.
EPA Enforcement and Water Divisions, NC-DNER, plant personnel, and an EPA
reconnaissance visit to the plants. The Lower Creek Wastewater Treatment
Plant was selected due to its difficulty in meeting the NPDES permit
requirements. Some work was also performed at the Gun Powder Creek
Wastewater Treatment Plant, even though plant performance was satisfactory
and the plant had not been turned over to the City by the contractor. 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
operational control techniques;
(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 data.
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The cooperation of the North Carolina Department of Natural and
Environmental Resources is gratefully acknowledged. The technical
assistance team is also especially appreciative for the cooperation and
assistance received from personnel of the Lower Creek and Gunpowder
Creek wastewater treatment plants.
2
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SUMMARY
LOWER CREEK WASTEWATER TREATMENT PLANT
The Lower Creek Wastewater Treatment Plant (WTP) was designed as a
6 mgd extended aeration activiated sludge system. At the time of the
study, flpw into the plant was approximately 1.99 mgd; therefore, only
one of two aeration basins and one of two clarifiers were being used.
The effluent BOD^ and TSS concentrations were less than 10 and 24 mg/1
with the addition of polymers and 20 and 41 mg/1 when not using polymers,
respectively. Operating records for the period July 1975 through July
1976 showed average effluent BOD5 and TSS concentrations of 33 and 40 mg/1,
respectively, without the use of polymers.
Major problems observed during the study are listed below:
(1) According to City officials the design flow (6 mgd) for the
WTP was greatly overestimated by the designer.
(2) The aeration basins are oversized for the extended aeration
activated sludge process.
(3) The maximum mixed liquor suspended solids concentration attain-
able since the plant began operation in 1969 has been about
200-300 mg/1.
(4) Solids have never been wasted from the treatment system.
(5) Based on the interpretation of a QS-EPA Notice of Violation
and Order, WTP officials began using a polymer costing
approximately $200 daily.
(6) Due to the light characteristics of the solids, a thick mat
of solids continually formed on the clarifier surface when the
polymer was used.
3
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(7) The return sludge pumps are high volume, constant speed
pumps, which do not permit variation in return rates.
(8) The approximate chlorine feed rate of about 220 pounds/day
was excessive. Based on the orthotolidine color
comparator the effluent chlorine residual was about
0.5 ppm, however with the EPA approved amperometric
titrater measured chlorine residuals were of 2.5-2.7 ppm.
(9) City officials have voted to have a consulting engineer
conduct a study to determine construction and design
revisions necessary to bring the Lower Creek WTP into
compliance with the NPDES permit requirements.
GUN POWDER CREEK WASTEWATER TREATMENT PLANT
The Gun Powder Creek WTP serving Southeast Lenoir, North Carolina
was designed as a 1.0 mgd contact stabilization activated sludge system
with additional nitrification of the effluent wastewater prior to final
settling. During the study, WTP influent flow averaged 0.23 mgd, with
a peak flow of 0.30 mgd. Average reductions of BOD^ and TSS were greater
than 93 and 95 percent, respectively. The activated sludge settled
rapidly, resulting in a turbid supernatant. The additional nitrification
system and polishing ponds made up for the lack of treatment optimization
in the contact stabilization system. Dissolved oxygen (DO) uptake
measurements indicated a poor quality sludge in terms of activity, but
low flows and long detention times were compensating factors.
4
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ems and inadequacies observed during the study are as follows
Influent flow measuring equipment was not calibrated.
Effluent sampling equipment was clogging due to location
of sample pickup orifice.
Volatile suspended solids content was only 47 percent of the
total suspended solids under aeration and reaeration.
Since the City of Lenoir had not accepted responsibility for
operations from the contractor, WTP personnel were unable to
make adjustments or process changes.
The scum trough in the nitrification settling tank was
flooded.
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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. Some of the recommendations have been
discussed with WTP personnel and have already been implemented.
LOWER CREEK WASTEWATER TREATMENT PLANT
1. The unused aeration basin should be employed as a settling lagoon.
This may provide the additional treatment necessary for compliance
with the NPDES requirements without using polymers.
2. As agreed upon by City officials, a consulting engineer should be
employed to study construction and design revisions necessary to
bring the Lower Creek WTP into compliance with the NPDES require-
ments.
3. The amperometric titrater should be used to measure chlorine
residual at the effluent.
GUN POWDER CREEK WASTEWATER TREATMENT PLANT
No recommendations are made for this plant since it was not in
full operation.
6
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LOWER CREEK WASTEWATER TREATMENT PLANT
TREATMENT FACILITY
Treatment Processes
A schematic diagram of the 6 mgd (design) extended aeration activated
sludge wastewater treatment plant (WTP) serving Lenoir, NC is presented in
Figure 1. Design data are enumerated in Table I. The WTP began operation
in 1969.
The wastewater treatment scheme consisted of comminutor, grit chamber,
aeration basin, clarifier, and chlorine contact chamber. Since influent
flows were less than 3 mgd, only one aeration basin and one clarifier were
operated. Chlorinated effluent was discharged into Lower Creek. A sludge
holding tank and drying beds were available, but had never been used.
Personnel
The WTP was staffed by eight persons of which two were certified.
One held a Class IV certification and the other a Class II.
Study Results and Observations
A complete listing of all analytical data and general study methods
are presented in the Appendix A and B. Significant results and observa-
tions are discussed in the following sections.
Flow
The WTP recorder and totalizer were not operating properly. Therefore,
plant flow was measured by installing a Stevens stage recorder on a 5-foot
rectangular weir (with end contractions) located at the effluent from the
7
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I UMMDU
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TABLK I
DESIGN DATA
LOWER CREEK WTP
LENOIR, NC
Flow Measurement
Type
Size
Location
Design Flow
Aeration Basins
Rectangular weir, recorder, totalizer
5 ft.
Effluent of chlorine contact chamber
6.0 mgd
Number
Volume (each basin)
Length
Width
Depth
Side Slopes
Aeration (each basin)
Clarifiers
895,722 cu. ft. (6.7 m. gal.)
401 ft.
221 ft.
12 ft.
2 :1
6-30 hp mechanical aerators
Number
Diameter
Depth (side wall)
Area
Volume
Weir Length
Sludge Holding Tank
Diameter
Depth (side wall)
Volume
Drying Beds
Number
Area (total)
2
95 ft.
9.5 ft.
7 ,088 sq. ft.
67,338 cu. ft. (.504 m. gal.)
300 ft.
72 ft.
15 ft.
456,823 gal.
8,200 sq. ft.
9
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chlorine contact chamber. The average flow during the study period was
1.99 mgd and ranged from a maximum of 2.68 mgd to a minimum of 1.18 mgd.
Approximately 60 percent of the raw influent flow was from industrial
sources and primarily from woodworking industries. According to WTP
personnel, the design flow was a gross over estimation of projected
flow into the plant.
10
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Waste Characteristics and Removal Efficiencies
Table II presents a chemical description of the WTP influent and
effluent wastewaters with calculated treatment reductions. Effluent
characteristics were determined with and without the use of polymer,
and based on one 24-hour composite sample under each condition.
Influent analyses were made on 24-hour, flow proportional composite
samples, collected on the first two days of the sampling period, and
the results averaged.
TABLE II
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
LOWER CREEK
WTP
Influent
Effluent
Reduction
Parameter
(mg/1)
* (mg/l) **
* (%)
ฆk-k
BOD 5
214
<10
20
>95
86
COD
492
58
96
88
80
TOC
175
23
35
87
80
Total Solids
540
246
279
54
48
Total Volatile Solids
268
52
79
81
71
Suspended Solids
310
24
41
92
87
Suspended Volatile Solids
180
19
31
89
83
Settleable Solids (ml/1)
18
<0.1
<0.1
>99
>99
TKN-N
21.0
14
15.7
33
25
NH3-N
13.2
13
11
1.0
16
N03-N02-N
0.04
.08
0.15
Total Phosphorus
6.2
4.3
4.4
31
29
Oil and Grease
29
<5
<6
>83
>79
Chlorine Residual
2.6
1.4
Lead
0.045
<0.05
<0.05
Chromium
<0.08
<0.08
<0.08
Cadmium
<0.01
<0.01
<0.01
Copper
0.056
0.022
0.016
61
71
Zinc
0.227
0.038
0.046
83
80
Turbidity (NTU)
10
42
* With polymer
** Without polymer
11
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The effects resulting from additions of the polymer are evident in
Table II. A review of plant operating records for the period from
July 1975 through 1976 showed average effluent BOD5 and TSS
concentrations of 33 and 40 mg/1, respectively, without the use of
polymers.
Influent pH (Figure 2) was monitored continuously from 10 a.m. on
September 21 to 8 a.m. on September 24. Influent pH remained fairly
constant at 6.8 between 8 p.m. and 10 a.m., but began to rise and
fluctuate greatly between 12 noon and 8 p.m. of each day. During the
study period, the highest daily pH values (9.4 and 9.2) were recorded
at approximately 7:30 p.m. on September 21 through 23. The high and
variable pH values during the afternoons were probably caused by indus-
trial discharges.
12
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PH
12 "
8
4 -
12"
8 -=|
4 -
12"
8
4 -
12"
8 ]
09/21/76
TUE
09/22/76
WED
09/23/76
THUR
09/24/76
FRI
FIGURE 2
INFLUENT pH
LOWER CREEK WTP
LENOIR N. C.
12
6
R. M
12
TIME CHRS)
6
P. M
1 2
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Aeration Basins
Grab samples were collected daily from the aeration basin. These
samples were analyzed for total suspended solids (TSS), volatile suspended
solids (VSS), percent solids by centrifuge, and settleability as deter-
mined by the settlometer. Various operational parameters, calculated
during the study period and the corresponding recommended values for the
extended aeration activated sludge process are presented in Table III.
TABLE III
ACTIVATED SLUDGE OPERATIONAL PARAMETERS
LOWER CREEK WTP
MLSS (mg/1)
MLVSS (mg/1)
Lbs BOD/day/lb MLVSS (F/M)
Hydraulic Detention Time (hrs)
Lbs BOD/day/1,000 cu.ft. of
aeration basin
Return Sludge Rate (% of
average plant flow)
Measured
160
95
.71
80
4.2
0**
Recommended (1)(6)(7)*
3,000 - 6,000
.05 - .15
18 - 36
10 - 25
75 - 150
* References appear on page 25.
** Negligible quantity of sludge pumped back to aeration basin twice
daily for approximately five minutes.
The calculated parameters in Table III are more typical of an
aerated lagoon operation rather than an extended aeration activated
sludge system. According to plant personnel, no sludge had ever been
wasted from the treatment system, nor had the MLSS concentration been
much greater than that observed during the TA study. Difficulty in
14
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building mixed liquor solids would be expected based on the tremendous
hydraulic detention time and gross over design of the basins. The
volatile content of the MLSS was 59 percent. The appearance of the
sludge coupled with this low volatile content, indicated that the solids
were over aerated, approaching an ash. These types of solids are light
and have a tendency to float rather than settle.
Dissolved oxygen concentrations (DO) in the aeration basin were
adequate. The DO range was 1.6 to 4.8 mg/1 (Appendix C). A few lower
concentrations were measured, but were at the 9 to 10 foot depths. A
sludge blanket appeared to exist throughout the aeration basin at depths
greater than 9 feet and accounted for the low DO measurements.
Clarifier
Only one of two circular clarifiers was operating during the study.
These clarifiers have a center feed, rim-takeoff flow configuration.
No sludge blanket was observed during the study because of the negligible
suspended solids entering the clarifier. Settled solids were pumped back
to the aeration basin by operating the 2,100 gpm constant speed return
sludge pump twice daily for approximately five minutes. The measured
and recommended operating parameters for secondary clarifiers following
the extended aeration activated sludge process are presented in Table IV.
15
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TABLE IV
SECONDARY CLARIFIER OPERATIONAL PARAMETERS
LOWER CREEK WTP
Measured Recommended (2) (4)
Hydraulic Loading (gpd/sq.ft.)
Solids Loading (lbs/day/sq . ft.)
Hydraulic Detention (hrs.)
Weir Overflow Rate (gpd/lin.ft.)
Depth (ft)
6
6,633
280
9.5
.37
200 - 400
20 - 30
2 - 2.5
15,000
8-12
The final clarifiers, which are conservatively designed, were not
effectively removing the suspended solids from the wastewater stream.
Polymers were applied to the clarifier influent to increase solids settle-
ability. Polymer utilization resulted in a thick floating mat of solids
on the clarifier water surface. To assess the effectiveness of the
chemical weighting agent, polymer addition was discontinued and the results
are presented in Table II. The use of chemical weighting agents should
not be considered as a long term treatment solution. Design flaws were
the major obstacles hindering satisfactory wastewater treatment.
The major flaw in clarifier design was the use of large constant
speed return sludge pumps instead of variable speed pumps.
The nature of problems at the plant were not operational, but over
design. City officials had voted at the time of this study, to undertake
a comprehensive engineering study to determine construction and design
revisions necessary to bring the WTP into compliance with NPDES require-
ments.
16
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Chlorine Contact Chamber
The typical chlorine feed rate at the WTP was 220 pounds/day which
corresponded to a residual chlorine concentration of about 0.5 mg/1,
using the orthotolidine color comparator. According to measurements with
an amperometric titrater, however, the effluent chlorine residual was
2.5-2.7 mg/1. On September 22 it was suggested that the chlorine feed
be reduced to 100 pounds/day. The subsequent residual ranged from 1.0
to 1.8 mg/1. On September 23 the chlorine feed was further reduced to
75 pounds/day. This subsequent residual ranged from 0.75-1.9 mg/1.
Throughout this period of reduction, the bacterial kill was adequate.
Based on a chlorine cost of $0.15/pound, these reductions averaged
$22/day, amounting to a savings of $8,000/year.
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GUN POWDER CREEK WASTEWATER TREATMENT PLANT
TREATMENT FACILITY
Treatment Process
The Gun Powder Creek Wastewater Treatment Plant (WTP) is a contact
stabilization activated sludge system serving Southeastern Lenoir, North
Carolina. A schematic diagram of the 1.0 mgd plant is presented in
Figure 3; design data are enumerated in Table V. The WTP began operation
in April 1976 and had not received a final inspection at the time of this
TA study.
Influent wastewaters entered the treatment complex through preliminary
units consisting of a mechanically cleaned bar screen, a 9 inch Parshall
flume equipped with totalizer and recorder, and grit chamber. After grit
removal, wastewater was pumped to one of two 0.5 mgd contact stabilization
tanks. Individual units of the contact stabilization tank included contact,
reaeration, and settling tank, plus an aerobic digester. Effluent waste-
waters from the settling tank flowed by gravity to separate nitrification
tanks. Clarified wastewater was then chlorinated and final settling was
accomplished in two 614,000 gallon polishing ponds.
Sludge from the contact tank settling basin was pumped to the reaera-
tion tank and/or aerobic digester. Sludge from the reaeration tank was
introduced to the contact tank through two rectangular ports. One port was
at the upper section and another at the lower section of the common wall
which separates the two tanks. A portion of the sludge generated in the
nitrification tank was wasted to the contact stabilization reaeration tank.
The remainder of the sludge was recycled within the nitrification system.
18
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FIGURE 3
GUN POWDER CREEK WTP
LENOIR, NG-"
Drying Beds
Contact Tank No. 1
Nitrification
Settling Basin No. 1
Influent
Structure
Pump
Station
/////- Not in operation
Wastewater flow
Sludge and underdrains
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GUN
TABLE V
DESIGN DATA
POWDER CREEK WTP
LENOIR, NC
Flow Measurement
Influent
Design flow
Average study flow
Influent Pumps
Number
Pump rating
Aeration Basins
9 in. Parshall flume, totalizer, recorder
1.0 mgd
0.23 mgd as measured by recorder
2 (one as standby)
2,100 gpm
Number
Volume (each)
Detention time (each)
Aerators
10,333 cu.ft. (77,500 gals.)
3.7 hr s @ 0.5 mgd
4-75 hp diffused air blowers (1,425 SCFM
@ 7 psi)
Clarifiers
Number
Volume (each)
Detention time (each)
4 (2-contact process, 2-nitrification process)
10,923 cu.ft. (81,925 gals.)
3.9 hrs. @0.5 mgd
Reaeration Basins
Number
Volume (each)
Detention time (each)
16,930 cu.ft. (126,970 gals.)
6 hrs. @0.5 mgd
Nitrification Basins
Number
Volume (each)
Detention time (each)
23,194 cu.ft. (173,950 gals.)
8.3 hours @ 0.5 mgd
Aerobic Digesters
Number
Volume (each)
Final Settling Pond
Number
Volume (each)
Detention time (each)
14,770 cu.ft. (110,775 gals.)
81,900 fu.ft. (614,250 gals.)
17 hrs. @ 0.5 mgd
20
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Personnel
The Gun Powder Creek WTP was staffed by two certified operators,
an operator assistant and two laboratory technicians. The plant is
operated for two eight-hour shifts.
STUDY RESULTS AND OBSERVATIONS
A complete listing of all analytical data and study methods are
presented in Appendices A and B. Significant results and observations
made during the study are discussed in the following sections.
Flow
Plant flow was measured by a 9 inch Parshall flume equipped with a
totalizer and recorder. Return sludge flow was not metered or measured.
Average hourly influent flow during the study was 0.23 mgd and varied
from 0.12 to 0.30 mgd. The return sludge flow was maintained at a
constant rate without any wasting.
Waste Characteristics and Removal Efficiencies
Table VI presents a chemical description of the WTP influent and
effluent wastewaters with calculated treatment reductions. Analyses
were made on 24-hour flow proportional composite samples, collected on
two consecutive days. Percent reductions were calculated from average
values. These data indicate that the WTP was meeting NPDES permit
limitations.
21
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TABLE VI
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
GUN POWDER CREEK WTP
Parameter
Influent
(mg/1)
Effluent
(rag/1)
Reduction
%
BOD5
152
<10
>93
COD
364
37
90
TOC
112
16
86
Total Solids
432
361
16
Total Volatile Solids
200
105
48
Suspended Solids
148
8
95
Suspended Volatile Solids
118
8
93
Settleable Solids (ml/1)
8
<0.1
>99
TKN-N
36.4
2.2
94
NH3-N
20.8
0.10
99
NO3-NO2-N
<0.01
11
Total Phosphorus
9.6
7.0
27
Oil and Grease*
16
<5
>69
Chlorine Residual*
0.9
Turbidity (NTU)
3
Lead
<0.05
<0.05
Chromium
<0.08
<0.08
Cadmium
<0.01
<0.01
Copper
<0.046
0.016
>65
Zinc
0.172
0.060
65
* Average results of grab
samples taken
on two different
days.
Aeration Basins
Grab samples were collected daily from the aeration and reaeration
basins. These samples were analyzed for total suspended solids (TSS),
volatile suspended solids (VSS), percent solids by centrifuge, and
settleability as determined by settlometer.
The oxygen uptake rate, a method of measuring sludge quality was
calculated using the depletion rate before and after introduction of the
raw waste. The calculated uptake rate (load ratio) was 1.7. A five
22
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minute depletion rate for the unfed sludge averaged 0.14 mg/l/min.;
a five minute depletion rate for the fed sludge averaged 0.25 mg/l/min.
One would expect reaerated sludge to be much more active when introduced
to the raw waste than was observed. The reason for this inactivity is
revealed through observation of the percent volatile content of the total
suspended solids. Volatile suspended solids content in the aeration
basin was only 47 percent. Most activated sludge mixed liquor solids
fall into a range of 70-80 percent volatile content. This content was
unusually low and indicated retention of undesirable oxidized solids.
Results from the settlometer test tended to compliment this data.
Mixed liquor solids settled rapidly to 50 percent (500 ml/1) or less
in five minutes, leaving a very turbid supernatant.
The above data and observations indicated that treatment can be
further enhanced by disposal of the undesirable solids and by increasing
the mixed liquor volatile content to 70-80 percent. Secondary treatment
was not optimized and the extra treatment units (nitrification-settling
and polishing pond) were responsible for the high treatment efficiencies.
Laboratory
The central laboratory for both the Gun Powder Creek and Lower Creek
WTPs was located at the Gun Powder Creek WTP. The staff included a
chemist and a laboratory technician who conducted a sampling program and
routine analyses for both plants. These analyses included: BOD5, COD,
DO, TS, TSS, settleable solids, TKN-N, residual chlorine, fecal coliform,
pH, and temperature. The laboratory was clean, adequate in size, and
well equipped.
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During the TA study, two afternoons were spent with the laboratory personnel,
and the following observations and recommendations were made:
(1) Generally, the laboratory personnel were conscientious
and exhibited good analytical techniques.
(2) The initial DO of the BOD5 dilution water was occasionally
as low as 4.5 ppm; however, it should be kept greater than
or equal to 7.0 ppm.
(3) Chlorine residual was determined by using the visual
orthotolidine method. The back titration procedure
presented in Standard Methods (5) was discussed and
recommended as a better procedure.
(4) The use of the centrifuge, settlometer test, and volatile
suspended solids analysis as control procedures for the
operations of WTPs were discussed.
(5) The use of trend charts was illustrated and discussed as
a tool for operational control.
During the TA study, five composite samples were split for chemical
analyses between EPA and Gun Powder Creek laboratory personnel for data
comparison of BOD5, COD, TSS, and TKN-N analyses. Generally, this data
compared well.
24
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REFERENCES
1. "Operation of Wastewater Treatment Plants", A Field Study Training
Program, US-EPA, Technical Training Grant No. 5TT1-WP-16-03, 1970.
2. "Process Design Manual for Suspended Solids Removal", US-EPA
Technology Transfer, January, 1975.
3. "Process Design Manual for Upgrading Existing Wastewater Treatment
Plants", US-EPA Technology Transfer, October, 1974.
4. "Sewage Treatment Plant Design", American Society of Civil Engineers,
Manual of Engineering Practice No. 36, 1959.
5. "Standard Methods for the Examination of Water and Wastewater",
13th Edition, 1971.
6. "Standards for Sewage Works", Upper Mississippi River Board of
State Sanitary Engineers, Revised Edition, 1971.
7. "Wastewater Engineering", Metcalf and Eddy, Inc., 1972.
8. Alfred W. West. Operational Control Procedures for the Activated
Sludge Process. Part I, Observations, April, 1973: Pages 7, 8.
25
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APPENDICES
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APPENDIX A
LABORATORY DATA
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APPENDIX^ A
LABORATORY DATA
LOWER CREEK & CUNPOWDER CREEK WTP
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APPENDIX' A
LABORATORY) DATA
ฆ LOWER CREEK & GUNPOWDER CREEK WTP
LENOIR, NC
INFLUENT & EFFLUENT
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ฆ APPENDIX A
LABORATORY DATA
LOWER CREEK & GUNPOWDER CREEK WTP'
LENOIR,' NC
AERATION BASINS & RETURN SLUDGE
STATION*
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APPENDlit A
LABORATORY DATA
LOITER CREEK &' GUNPOWDER CREEK WTP
LENOIR. NC .
NITRIFICATION TANK, DIGESTER CLARIFIERS
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APPENDIX B
GENERAL STUDY METHODS
-------
APPENDIX B
GENERAL STUDY METHODS
To accomplish the stated objectives, the study included extensive
sampling, physical measurements, and daily observations. Gun Powder
Creek. WTP influent and effluent stations were sampled for two consecutive
24-hour periods. Lower Creek WTP influent station was sampled for three
consecutive 24-hour periods, but because of an inoperative sampler, the
effluent station was sampled for only two consecutive 24-hour periods.
A Stevens Type F water level recorder was installed on the Lower
Creek plant effluent to record gage heights on the rectangular weir
through the 24-hour compositing periods. These gage heights were converted
to daily total flow (mgd). Dissolved oxygen was determined at stations
throughout the plants and in the aeration basins using a YSI Model 51A
dissolved oxygen meter. An Analytical Measurements Model 30 WP cordless
pH recorder was installed at both plants to continuously monitor influent
pH throughout the sampling period. Temperatures and pH were determined
at other stations with a thermometer and portable pH meter.
Depth of the secondary clarifier sludge blankets were determined
daily by use of equipment suggested by Alfred W. West, EPA, NFIC,
Cincinnati. Sludge activity was determined by the oxygen uptake procedure
presented in Appendix D.
The following series of standard operational control tests were
run daily:
(1) Settleability of mixed liquor suspended solids (MLSS)
as determined by the settlometer test;
B-l
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(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;
(A) Turbidity of each final clarifier effluent.
An amperometric titrator (Fischer & Porter Model 17T1010) was used
to determine effluent chlorine concentrations. The procedure for BOD5
determinations deviated from Standard Methods. Samples were set up and
returned in an incubator to Athens, Georgia for completion. 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 U.S. Environmental Protection
Agency.
B-2
-------
APPENDIX C
AERATION BASIN DISSOLVED OXYGEN CONCENTRATIONS -
LOWER CREEK WTP
-------
APPENDIX C
AERATION BASIN DISSOLVED OXYGEN CONCENTRATIONS
LOWER CREEK WTP, LENOIR, NC
N
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~
1-9
1-10
ft 1-11
1-5
1-6
1-7
1-8
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1-3
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DEPTH
DO
TEMP
STATION
(FT)
(ฐC)
1-1
1
0.0
20
1-2
1
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20
5
4.1
Aerator on
8
3.6
10
0.2
1-3
1
4.0
5
3.8
10
3.5
11
3.0
Sludge below 11
1-4
1
3.4
Aerator off
5
3.1
10
3.1
Sludge below 10
1-5
1
3.0
Aerator on
5
2.9
10
2.8
1-6
1
3.7
5
3.4
9
3.3
10
3.0
1-7
1
3.6
5
3.4
8
3.2
9
0.0
1-8
1
2.4
Aerator off
5
2.6
8
2.3
10
0.0
1-9
1
2.6
Aerator off
5
2.4
8
1.8
Sludge below 8
1-10
1
2.0
Aerator off
5
1.8
8
1.8
10
1.6
1-11
1
2.4
Aerator on
5
2.2
8
2.0
C-l
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APPENDIX D
OXYGEN UPTAKE PROCEDURE
-------
APPENDIX D
OXYGEN UPTAKE PROCEDURE ฑJ
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 = 121 = 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
while transferring the contents. Re-invert and shake again
while returning the sample to the orgiinal test bottle. The
sample should now be well mixed and have a high D.0.
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 1 minute intervals until at least 3
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).
Dซ1
-------
Appendix (cont'd)
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. Teh 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
poinsoned 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.
D-2
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APPENDIX E
PROJECT PERSONNEL
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APPENDIX E
Ronald Barrow
Herb Barden
Lavon Revells
Tom Sack
Eddie Shollenberger
Richard Rehm
PROJECT PERSONNEL
Sanitary Engineer
Microbiologist
Chemist
Technician
Technician
Student Trainee
E-l
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