EL'A 904/:.; -/"/• t'03
TECHNICAL ASSISTANCE PROJECT
AT THE
SOUTH BUFFALO CREEK WASTEWATER TREATMENT PLAN?
GREEN S3 0X0, NORTH CAROLINA
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Environmental Protection Agency
Region IV
Survr> illatiCC and AralLd Division
Ativans > <¦"¦¦¦ i
i)ecentbar 1S76
-------
EPA 904/9-77-003
TECHNICAL ASSISTANCE PROJECT
AT THE
SOUTH BUFFALO CREEK WASTEWATER TREATMENT PLANT
GREENSBORO, NORTH CAROLINA
Environmental Protection Agency
Region IV
Surveillance and Analysis Division
Athens, Georgia
December 1976
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TABLE OF CONTENTS
Introduction .......... 1
Summary 3
Recommendations 6
Treatment Facility , .... 8
Treatment Processes ..... 8
Personnel ' 9
Study Results and Observations 14
Flow 14
Waste Characteristics and Removal Efficiencies ... .11
Primary Sedimentation Basins ... .22
Trickling Filters 24
Aeration Basins 25
Secondary Clarifiers 33
Chlorine Contact Chamber 36
Sludge Handling 37
Laboratory. 37
References 40
Appendices
A. Laboratory Data
B. Influent COD
C. General Study Methods
D. Dissolved Oxygen Concentrations
E. Turbidity-Flow Relationship
F. Oxygen Uptake Procedures
G. Project Personnel
H. Sludge Blanket Finder
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Figures
1. South Buffalo Creek WTP 10
2. Flow, DTB, Effluent Turbidity 15
3. Influent pH 19
4. Profiles Through Plant of Selected Parameters 20
5. Nutrient Profiles Through WTP 21
6. Hourly COD Loading 23
7. Aeration Basin Dissolved Oxygen Concentrations .... 28
8. Average Settlometer Results for Each Aeration Basin. • 31
9. Daily Average Settlometer Results for Station A-5 • . .32
10. Clarifier Dye Study 35
TABLES
I. Design Data 11
11. Rainfall Data 16
III. Waste Characteristics and Removal Efficiencies 17
IV. Primary Sedimentation Operational Parameters 24
V. Activated Sludge Operational Parameters 26
VI. Oxygen Uptake Rates 30
VII. Secondary Clarifier Operational Parameters 33
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INTRODUCTION
A technical assistance study of operation and maintenance problems
at the South Buffalo Creek Wastewater Treatment Plant, Greensboro, North
Carolina was conducted December 13-17, 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 personnel in maximizing treatment efficiencies,
as well as assisting with special operational problems.
The selection of this plant was based on a request from city
officials of Greensboro, NC. The study was coordinated with the U.S.
EPA Enforcement and Water Divisions and the NC-DNER. The South Buffalo
Creek WTP was chosen because of its difficulty to achieve design treat-
ment efficiencies. 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
characteristics;
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 operation and maintenance practices
will be conducted by June 1977. This will be accomplished through
utilization of data generated by plant personnel. If necessary,
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subsequent visits to the facility will be made. The follow-up assess-
ment will determine if recommendations were successful in improving
plant operations and if further assistance is required.
The cooperation of the North Carolina Department of Natural and
Economic Resources is gratefully acknowledged. The technical
assistance team is also especially appreciative for the cooperation and
assistance received from personnel of the City of Greensboro, NC and
South Buffalo Creek WTP.
2
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SUMMARY
The South Buffalo Creek Wastewater Treatment Plant (WTP) was
originally constructed in 1931 and through numerous modifications has
evolved to the existing 12 mgd conventional activated sludge WTP. The
average flow during July 1975 to June 1976 was 9.6 mgd. The average
flow during the study period was 12.8 mgd and ranged from 8 to 15 mgd.
At these flows, many of the treatment units were hydraulicly overloaded
and the aeration basins were organically overloaded. The reductions in
BOD,, and TSS during the study period were 91 and 60 percent, respectively.
Major observations during the study are listed below:
1. The primary sedimentation basins were hydraulicly over-
loaded and were achieving poor TSS removal (14 percent).
2. There was no means to measure flow to the trickling
filters; consequently the organic load to the aeration
basins cannot be accurately determined.
3. The method of cleaning the trickling filter distribution
arms resulted in excessive solids flowing into both
final clarifier effluent troughs.
4. The aeration basins frequently overflowed, spilling
onto the plant grounds.
5. The mean cell residence time (MCRT) was short(4.2 days).
6. The organic load to the aeration basins was excessive.
7. The water levels in aeration basins //I and //2 were
about 5 inches lower than in aeration basins //3 and #4.
3
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8. Generally, dissolved oxygen concentrations in all four
aeration basins were too low, with the lowest measure-
ments in basins #1 and #2.
9. The activated sludge settleability was adequate, but
left a turbid supernatant.
10. Solids carry-over from the secondary clarifiers was
directly related to plant flow. The sludge blanket
consistently rose with increasing plant flow.
11. The sludge blanket in clarifier //2 was consistently
higher than the blanket in clarifier #1.
12. The return sludge pumps were constant speed and limited
to only about 40 percent of the WTP design flow, based
on the operation of two pumps. An additional stand-by
pump was available.
13. Effluent total chlorine residuals ranged from 2.45 to
3.05 ppm during the study, based on the amperometric
back titration method.
14. Based on the variation in hourly COD loadings and pH,
the WTP receives occasional batch discharges from
industrial sources.
15. Effluent samples collected for BOD^ analyses were not
dechlorinated and seeded, thus possibly producing
erroneous data.
16. The lodometric direct titration method was used to
determine chlorine residual in the plant effluent.
4
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A right angle bend in the influent channel immediately
upstream from the Parshall flume caused considerable
turbulence in the approach and throat of the flume.
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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. Trend charts and operational testing
will assist in determining optimum control. It is recognized that
hydraulic and other restraints within the plant may hamper complete
implementation of these recommendations.
1. The mean cell residence time (MCRT) should be increased
gradually to increase the activated sludge settling
rate. This will cause a turbid effluent to be discharged
to the sand filters, but should help hold the majority
of the suspend solids in the final clarifiers. The
subsequent increase in the MLSS concentration may cause
additional operational problems with the final clari-
fiers. Activated sludge settleability will dictate the
extent of this operational change.
2. The stand-by return sludge pump should be operated and
alternated between the two clarifiers to help balance and
hold down the sludge blankets. This will require taking
periodic sludge blanket depth measurements and will also
require acquisition of a sludge blanket finder (Appendix H).
3. The return sludge pick-up and pumping system should be
inspected closely to determine the cause for unbalanced
final clarifier operation.
6
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4. The dissolved oxygen concentration in the aeration
basins should be maintained in the 1.0 to 2.0 mg/1
range, and monitored in each basin regularly with an
electronic DO meter.
5. The aerators should be checked to see that they are
delivering maximum efficiency. This can be done by
checking the electrical current usage and depth of
submergence.
6. The technique for cleaning the trickling filter
distributor arms should be changed to eliminate flushing
onto the grounds and subsequent flow into the final
clarifier effluent trough.
7. The primary sedimentation basins should be upgraded to
handle the existing hydraulic load.
8. The back titration method discussed in Standard Methods
should be used to determine chlorine residuals in waste-
water. Acquisition of an amperometric titrator would
reduce chlorine use and represent a monetary savings.
9. An in-plant control testing schedule should be initiated
immediately, and trend charts established and maintained.
10. The BODj. samples collected after chlorination should be
dechlorinated and seeded.
11. Samples for dissolved oxygen measurements should be
collected such that oxygen is not introduced into the
sample.
7
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TREATMENT FACILITY
TREATMENT PROCESSES
A schematic diagram of the 12 mgd, South Buffalo Creek Wastewater
Treatment Plant (WTP) is presented in Figure 1. Design data are
enumerated in Table I. The original plant (3.25 mgd) was built in
1931 and consisted of a primary clarifier, fixed nozzle trickling
filter and anaerobic digester. The WTP was modified in 1957-59.
Construction included two high-rate trickling filters, two secondary
clarifiers, a chlorine contact chamber, anaerobic digester and vacuum
filter. The old anaerobic digester was removed from service.
During the period 1965-70, the fixed nozzle trickling filters were
converted to four activated sludge aeration basins. During 1974-76
construction included a pre-aeration basin, an additional primary
clarifier, a return sludge pump station, sand filters, and a laboratory.
The vacuum filter was renovated and the primary clarifiers were covered.
The OTP serves an approximate population of 75,000. Approximately
65 percent of the influent flow was from industrial sources including
textile mills, slaughter houses, chemical and fertilizer plants.
Existing treatment consists of screening, grit removal, pre-
aeration, primary sedimentation, high rate trickling filters, activated
sludge, final clarification and chlorination. Chlorinated effluent
was discharged into South Buffalo Creek which has a Class "D" water
quality classification. Sludge conditioning consisted of air flota-
tion, anaerobic digestion, vacuum filtration and incineration.
Digester supernatant and vacuum filter filtrate were returned to the
8
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head of the plant. Underflow from the air flotation unit flows into
the itA aeration basin. Sand filters have been constructed but
mechanical and operational problems have limited their use.
PERSONNEL
Of the 17 persons working at the plant, ten hold the following
certification ratings: 2-IV, l-III, 6-II and 1-1. The plant was
staffed on a 24-hour basis.
9
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FIGURE 1
SOUTH BUFFALO CREEK WTP
GREENSBORO, NC
Aeration Basins
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TABLE I
DESIGN DATA
SOUTH BUFFALO CREEK WTP
GREENSBORO, NC
Flow Measurement
Influent
Return sludge
Plant design flow (avg)
(max)
Grit Chamber
Type
Length
Width
Depth (avg)
Volume
Preaeration Basins
Type
Number
//I Chamber
Length
Width
Depth
Volume
#2 Chamber
Length
Width
Depth
Volume
Primary Clarlfiers
Number
#1 (Circular)
Diameter
Depth
Area
Volume
Weir length
24 in. Parshall flume, recorder,
totalizer
Magnetic flow meter
12 mgd
16 mgd
Diffused air
20 ft.
10 ft.
11.3 ft.
2,260 cu.ft.
Diffused air
2
36 ft.
22 ft.
14.2 ft.
11,240 cu.ft. (84,075 gal.)
33 ft.
22 ft.
14.2 ft.
10,300 cu.ft. (77,100 gal.)
2
80 ft.
9.3 ft.
5,026 sq.ft.
46,740 cu.ft.
251 ft.
11
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TABLE I (cont)
//2 (Rectangular)
Length
Width
Depth
Area
Volume
Weir length
Trickling Filters
Number
Type
Diameter
Depth
Surface area (each)
Aeration Basins
Number
Length
Width
Depth
Volume (each)
(total)
Aeration
Basin #1
Basin #2
Basin #3
Basin #4
Total Aeration Capacity
Final Clarifiers
Number
Diameter
Depth (SWD)
Area (each)
Volume (each)
Weir length (each)
70 ft.
70 ft.
11.4 ft.
4,900 sq.ft.
55,860 cu.ft. (417,830 gal.)
70 ft.
2
High rate
155 ft.
5 ft.
18,869 sq.ft.
4
196 ft.
100 ft.
7.5 ft.
147,000 cu.ft. (1.1 m.gal.)
588,000 cu.ft. (4.4 m.gal.)
4-10 hp., 4-15 hp. stationary
mechanical aerators
4-10 hp., 4-15 hp. stationary
mechanical aerators
6-20 hp., 2-30 hp. floating mechanical
aerators
6-20 hp., 2-30 hp. floating mechanical
aerators
560 hp.
2
105 ft.
9 ft.
8,659 sq.ft.
77,930 cu.ft. (.583 m.gal.)
330 ft.
12
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TABLE I (cont)
Chlorine Contact Chamber
Aerated
Length
Width
Depth (avg)
Volume
4 mechanical surface aerators
50 ft.
50 ft.
9.5 ft.
23,750 cu.ft.
13
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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 F. Significant results
and observations made during the study are discussed in the following
sections.
FLOW
Plant flow was determined from a 2 foot Parshall flume installed
on the WTP influent which was equipped with a recorder and totalizer.
A right angle bend in the influent channel immediately upstream from the
flume probably effects flow measurement accuracy. The recorder was
checked and found to be accurate.
Average plant flow during the study period was 12.8 mgd and ranged
from about 8 to 15 mgd. Rainfall during the month of December 1976 is
presented in Table II. Rainfall on December 11, 12, 15 caused higher
than typical flow into the WTP. The annual average flow for the period
July 1975 - June 1976 was 9.6 mgd. Hourly plant flow during the study
period is presented in Figure 2. Plant flow for December 1976 is pre-
sented in Appendix E.
Return sludge flow (RSF) was measured with a magnetic flow
meter equipped with a recorder and totalizer. The constant speed
return sludge pumps returned an average of 4.7 mgd (37 percent of WTP
inflow) during the study.
Waste sludge flow (WSF) was determined by plant personnel using a
bucket and stopwatch. The average WSF during the study was 273,000 gpd.
Waste sludge flow includes sludge returned back to the head of the WTP
14
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1
3
5
7
9
16
1.4
12
10
8
140
120
100
80
60
40
20
0
FIGURE 2
FLOW, DTB, EFFLUENT TURBIDITY
Key:
• - EPA sample, clatitier 111
Dec 14 Dec 15 Dec 16 Dec 17
15
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to be collected in the primary clarifier and sludge discharged directly
into the air flotation unit.
Digester supernatant, in-plant drains and vacuum filter filtrate
were discharged back to the head of the plant. The average instantaneous
flow was approximately 12 gpm (sampling station DR).
TABLE II
RAINFALL DATA
24-Hour
24-Hour
24-Hour
Day
Amount
Day
Amount
Day
Amount
Dec. 1976
(in.)
Dec. 1976
(in. )
Dec. 1976
(in.)
1
0
11
.51
21
0
2
0
12
.13
22
0
3
0
13
0
23
0
4
0
14
0
24
0
5
0
15
.82
25
.57
6
1.20
16
.02
26
0
7
.21
17
0
27
0
8
.26
18
0
28
0
9
0
19
0
29
0
10
0
20
.47
30
.04
31
0
16
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WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
A chemical description of the WTP influent and effluent waste-
waters with calculated treatment reductions is presented in Table III.
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.
Residual chlorine analysis was conducted on grab samples and the results
were averaged.
TABLE III
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
SOUTH BUFFALO CREEK WTP
PARAMETER
INFLUENT
(rog/1)
EFFLUENT
(mg/1)
REDUCTION
(%)
BOD
COD
TOC
TS
TVS
TSS
VSS
363
791
283
663
374
175
139
34
246
157
392
127
70
55
<0.1
14.5
9.4
<0.05
6.3
<0.050
<0.050
0.063
<0.010
0.135
3.09
91
69
45
41
66
60
61
>98
45
25
>50
-11
Settleable solids(ml/l)
TKN-N
NH -N
MO -NO -N
5.0
26.6
12.5
0.10
5.7
<0.057
<0.060
0.085
<0.010
0.230
Pb
Cr
Cu
Cd
Zn
25
41
CI2 Residual*
*Analysis conducted on grab samples.
17
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The average composite influent BOD,. (363 mg/1), COD (791 mg/1),
and TOC (283 mg/1) concentrations represented a strong waste which
might be expected with the high percentage (65%) of industrial flow
discharged to the plant. The effluent ratios for COD/BOD,. and
TOC/BOD,. were 7.2 and 4.6, respectively. These rather high ratios
indicate that a large portion of the waste material is not easily or
rapidly broken down by biological means. This is typical of textile
wastes due to the wide variation of organic compounds used in the
industry. Some of these compounds decompose rapidly., some decompose
slowly and others are essentially unaffected by biological treatment.
Influent pH was monitored continuously from 10 a.m. December 14
to 10 a.m. December 17, 1976 except for a three hour period on
December 16. These results are depicted in Figure 3. The pH remained
steady between 6.0 and 7.0 except for an occasional fluctuation. The
pH values ranged from 5.0 to 9.8. The rapid and substantial pH changes
were probably caused by dumping of strong alkaline waste in the waste-
water collection system. These changes were not considered to have been
detrimental to the treatment process.
Figure A depicts concentrations of COD, BOD,., TSS, and VSS.
Figure 5 depicts concentrations of phosphorus, TKN-N, NH^-N, and
NO^-NO^-N in the influent and effluent of each treatment unit.I
These results will be discussed in following sections dealing with each
18
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12"
8 —
4 —
12/14/76
TUE
PH
1 2 ~I
B —
4 —
12"
8 —
4 —
12/15/76
WED
12/16/76
THUR
FIGURE 3
INFLUENT PH
SOUTH BUFFRLD WTP
GREENSBORO, N. C.
12"
B —I
4 -
12/17/76
FR I
12
6
R. M.
12
TIME CHRS)
6
P. M.
1 2
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FIGURE 4
PROFILES THROUGH PLANT OF SELECTED PARAMETERS
800
A\\\
\\\ \
« \\
, • \
XN
>.\\
N\
BOD
I influent
p primary effluent
T trickling filter effluent
E final effluent
20
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30
FIGURE 5
NUTRIENT PROFILES THROUGH WTP
SOUTH BUFFALO CREEK WTP
GREENSBORO, NC
TKN-N
u
24
<
OE
O
o
a
<
ec
u
>
<
18
12
TOTAL P
I - Influent
P-Primary effluent
T-Trickling filter effluent
E-Final effluent
no3-no2-n
0.10
0.05-
0. 0.
I P T E
I P T E
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treatment unit. In general, each unit reduced the concentration of
the indicated parameters less than expected. There was also no
significant degree of nitrification taking place in the treatment
system (Figure 5).
Hourly influent samples for fifty-two consecutive hours (December
14 to December 16, 1976),were collected for COD analysis. The results
are shown in Figure 6 and given in Appendix B. These concentrations
ranged from 391 mg/1 (43,044 lbs./day) to 2,868 mg/1 (327,692 lbs./day).
It appears from the irregular peak loadings depicted in Figure 6 that
the WTP was receiving batch discharges.
PRIMARY SEDIMENTATION
The primary sedimentation unit consisted of one circular and one
rectangular tank. The circular tank had a center-feed, rim take-off
flow configuration. Influent wastewater flowed into one end of the
square tank and out of the opposite end. Sludge was pumped from the
center of both tanks to the anaerobic digester. The original sludge
scrappers in the square tank had extendible arms to reach the corners,
however, these never worked and the extensions were removed. Sludge
was allowed to build up in the corners of the square tank.
Each tank was assumed to receive about half the incoming plant
flow (6.4 mgd each). Table IV gives measured and recommended design
values for primary sedimentation tanks. The surface loading and
weir overflow rates exceeded recommended values for both tanks. This
hydraulic overload was probably the major cause of poor treatment
efficiency achieved by these primary units.
22
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FIGURE 6
HOURLY COD LOADING
300
>.
¦o
0)
.o
O
o
o
a
o
a
20 Q__
1 0D_j_
12/15
TOME
4 pm
. A, i i._J. A
8 pm M
4am
8am
_Al
H
12/16
-------
The BOD,, and TSS removals through the primary sedimentation
tanks (Figure 4) were only 7 and 14 percent, respectively.
TABLE IV
PRIMARY SEDIMENTATION OPERATIONAL PARAMETERS
Measured*
Rectangular Circular
Parameters Tank Tank Recommended (2)(4)(11)
Detention Time
(hrs.) 1.57 1.31 1-2
Surface Loading
(gpd/sq.ft.) 1,306 1,273 600-1,200**
Weir Overflow Rate
(gpd/lin.ft.) 91,430 25,500 <15,000
*Assuming equal flow to each sedimentation tank.
**Preferably 600-800 gpd/sq.ft. with waste activated sludge returned
to the primary sedimentation tanks (3).
TRICKLING FILTERS
A portion of the flow from the primary sedimentation tanks was
treated by two trickling filters operated in parallel. There was no
method available to determine flow to the trickling filters. About
41 and 20 percent of the B0D5 and TSS, respectively, entering the
trickling filters were removed (Figure 4).
The distributor arms were cleaned by opening both ends and
flushing. Drains located between the filters collected the discharge
from one end of each arm. However, the discharge from the opposite
end of each arm flushed onto the ground and flowed into the effluent
24
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trough of each clarifier. Observations revealed that this wastewater
contained a large quantity of solids which were picked up from the
flushing operation and from flowing over the ground. A more satis-
factory method of cleaning the distribution arms would be to open only
one end of each arm at a time, rotating each arm as needed to allow
the wastewater to drain into the drainage pit located between the
filters.
AERATION BASINS
Grab samples were collected daily from each of the four aeration
basins and from their combined discharge. These samples were analyzed
for total suspended solids (TSS), volatile suspended solids (VSS),
percent solids by centrifuge, and settleability as determined by the
settlometer. Presented in Table V are various activated sludge opera-
tional parameters based on data collected during the study and the
corresponding recommended values for the conventional activated sludge
process.
The organic loading to the aeration basin could not be determined
accurately because the portion of plant flow by-passing the trickling
filters was variable and unknown. However, assuming 1/4, 1/2, and 3/4
of the plant flow passing through the trickling filters, the respective
F/M ratio's and organic loadings are presented in Table V. In all
three cases the F/M ratio exceeded or was near the maximum recommended
values indicating the need to increase the MLSS concentrations. The
organic loading based on lbs. BOD/day/1,000 cu.ft. indicates insufficient
aeration basin capacity.
25
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TABLE V
ACTIVATED SLUDGE OPERATIONAL PARAMETERS
SOUTH BUFFALO CREEK WTP
MLSS (mg/1)
MLVSS (mg/1)
Hydraulic Detention Time (hrs)
Mean Cell Residence Time (days)
Lbs. BOD/day/MLVSS (F/M)
1/4**
1/2**
3/4**
Lbs. COD/day/MLVSS
1/4**
1/2**
3/4**
Lbs. BOD/day/1,000 cu.ft.
aeration basin 1/4**
1/2**
3/4**
Return sludge rate (% of
average plant flow)
Measured
2,058
1,930
6.0
4.0
.46
0.41
0.35
1.01
0.93
0.85
56
49
43
37
Recommended (2)(5)(7)*
1,500-3,000
4-8
5-15
0.2-0.4
0.5-1.0
20-40
25-50
*References 1-13 appear on page 40
** - Assuming 1/4, 1/2, 3/4 of plant flow to trickling filters.
26
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Results presented in Table V Indicate that the MLSS and MCRT
should be increased. Increasing the MCRT should increase the settling
rate. Increasing the MLSS may cause some problems in holding solids
in the secondary clarifiers, particularly with the constant speed
return sludge pumps. Ability to hold the solids in the clarifiers will
dictate the maximum MLSS concentration.
The discharge from aeration basins It1 and #2 is combined in a
36-inch pipe and the discharge from aeration basins #3 and #4 is
combined in a 24-inch pipe. Both discharges flow into the final clari-
fiers. The water level elevations of basins #3 and #4 were usually
5 inches higher than basins //I and #2. During daily high flow periods
basins //3 and /Mspilled over onto the plant grounds indicating an
obstruction in the pipe or insufficient pipe size.
The size and placement of aerators along with ranges in dissolved
oxygen (DO) measurements are presented in Figure 7. A complete listing
of DO concentrations is presented in Appendix D. Aeration basins //I
and //2 contain fixed mechanical aerators with a total aeration capacity
of 100 hp each. Aeration basins If 3 and #4 contain floating aerators
with a total aeration capacity of 180 hp each. At most sampling stations
DO concentrations were higher on December 14 than on December 15 and 16.
Generally the DO concentrations were too low, with lowest measurements
being in aeration basins #1 and //2.
The oxygen uptake rate is helpful in evaluating sludge activity.
This activity is measured by mixing return activated sludge with influent
(fed) and nonchlorinated effluent (unfed) wastewater and determing the
27
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FLfiURE 7
AERATION BASIN DISSOLVED OXYGEN CONCENTRATIONS
SOUTH BUFFALO CREEK WVP
CREENSBORO. NC
® o
<2.0-0.4),
30 HP
C (2.8-0.6)
30 HP
20 HP
BASIN 4
20 IIP 20 HP
-r
D _ /
(0.2) Q /
2() IIP
20 Tip
C (O.i-o.b)
30 IIP
BASIN 3
20 IIP
20 HP
(2.4-0. 6)"
B
15 HP
C (0-2.0)
15 HP
B
0 (0-0.5) 0
10 IIP 10 HP
BASIN 2
10 IIP 10 HP
15 HP
C (0-2.6)
15 HP
10 HP
BASIN 1
10 HP
10 HP
(0-L.0)
B
10 HP
©
KEY:
20 HP
20 HP
(].2-0.3)
A
o
(0.0-0.5) A
20 IIP
15 HP
(0-0.7) A
15 UP
15 HP
(0-0.7) A
15 IIP
Mechanical Aerator
Mechanical Aerator (not operating)
Missing Aerator
( ) Range in dissolved oxygen concenLrations during study
period
— Accumulated Sludge
28
-------
uptake rate, then calculating the load ratio (LR).
j „ ADO (mg/l/min) fed sludge
Load Ratio = . r — r-52^
ADO (mg/l/niin) unfed sludge
The detailed procedure for this test is contained in Appendix F. The
load ratio reflects the conditions at the beginning and end of aeration.
Generally, a load ratio from 2 to 5 signifies an abundant, acceptable
feed under favorable conditions. A small LR (<2) may mean dilute feed,
sick sludge, poorly acceptable feed, or other unfavorable conditions.
A LR less than 1.0 indicates that a wastewater constituent shocked or
poisoned the "bugs". A LR greater than 5 usually indicates a young
under-oxidized sludge which may bulk (12).
During the study, oxygen uptake rates or load ratios were
calculated for both the waste from the primary units and the trickling
filters. These calculations and the accompanying data are presented
in Table VI. The measured oxygen uptake rates are low for an unfed
activated sludge, and are indicative of an over-oxidized sludge.
Often times an over-oxidized sludge results in straggler floe or pin
floe in the effluent. Generally an unfed activated sludge would utilize
on the average 0.4 - 0.6 mg/l/min of oxygen.
Calculated load ratios utilizing the activated sludge oxygen
uptake rates and the two feed sources indicate an acceptable biodegradable
influent waste. Conventional activated sludge processes generally operate
in the load range of 2 to 4 for best results and optimum BOD^ removal.
29
-------
TABLE VI
OXYGEN UPTAKE RATES'
Average 0„ Uptake
Load Ratio
DATE
/ RS
URS—^
mg/l/min
PFRS—^
mjt/l/min
3/
TFRS—
mg/l/min
PFRS/
URS
TFRS,
URS
12/14/76
31.3
0.28
-
0.84
-
3.00
12/15/76
30.2
0.28
1.40
1.01
4.94
3.56
12/16/76
30.2
0.38
1.32
1.65
3.48
4.34
Another indicator of sludge quality is the settleability of acti-
vated sludge as determined by the settlometer test. Figure 8 shows the
average settleability curves of each basin (A-l,A-2,A-3,A-4) for the
study period. After five minutes the settled sludge volume (SSV) ranged
from 70 to 80 percent and after sixty minutes the SSV ranged from 26 to
30 percent. These SSV values indicate a good sludge which is compacting
well. Figure 9 shows the settleability curves of the composite of all
four basins (A-5) for the three-day period. The curves for December 14
and 16 indicate a good sludge which is compacting well, but the curve
for December 15 indicates a deteriorated sludge quality which is not
compacting well. This deteriorated condition was the result of heavy
rain during the day which caused aeration basin flooding.
_1/ - URS - Unfed Return Sludge using clarifier effluent
2/ - PFRS - Fed Return Sludge using primary effluent
3/ - TFRS - Fed Return Sludge using trickling filter effluent
30
-------
FIGURE 8
RVERRGE SETTLOMETER RESULTS FOR EACH RERRTION BRSIN
SOUTH BUFFRLO CREEK NT P
SI
ta
Ld
in
r-
CD
U
~ m
if)
~
LJ m
i fN
U
CD
si
0
H fl-1
X fl-3
H R-4
10
20 30 40
TIME C M I N)
50
60
-------
LO
ho
FIGURE 9
DRILY AVERAGE SETTLOMETER RESULTS FOR STATION fl-5
SOUTH BUFFALO CREEK WTP
s
S3
u
in
r-
O
>
LJ
O 13
a1"
cn
~
LJ in
i
-------
SECONDARY CLARIFIERS
Both circular clarifiers had a center feed, rim take-off flow
configuration with a center baffle to distribute incoming flow. The
measured and recommended operating parameters for secondary clarifiers
following the conventional activated sludge process are presented in
Table VII. The measured values are based on the average flow during
the study of 12.8 mgd and the average annual flow of 9.6 mgd.
TABLE VII
SECONDARY CLARIFIER OPERATIONAL PARAMETERS
SOUTH BUFFALO CREEK WTP
Measured Recommended
12.8 mgd 9.6 mgd (3)(A)(7)
Hydraulic Loading
(gpd/sq.ft.) 739 554 400 - 800
Solids Loading
(lbs/day/sq.ft.) 12.7 - 20-30
Hydraulic Detention (hrs.) 1.6* 2.0* 2 - 2.5
Clarifier ft 1 1.6**
Clarifier ft2 1.4**
Weir Overflow Rate
(gpd/lin.ft.) 19,394 14,545 15,000
* - calculated as volume/flow
** - measured by dye study
The clarifiers were operating within recommended design criteria
except for the weir overflow rate (WOR). The position of the weirs
further encourages high upflow velocities causing solids carryover.
33
-------
This problem becomes critical during peak flows and is compounded by
the inability to increase the return sludge flow rates.
The results of the clarifier dye tracer study are presented in
Figure 10. The area under the two curves (Figure 10) represents the
flow split to the two clarifiers which was 56 and 44 percent to clari-
fiers //I and //2, respectively. The hydraulic detention time was
determined as the centroid of the curves for clarifiers //I and //2 and
were determined as 93 and 84 minutes, respectively.
The relationship between plant flow, turbidity, and depth to sludge
blanket (DTB) is presented in Figure 2. The DTB is the distance
measured in feet from the clarifier water surface down to the top of
the sludge blanket. The DTB consistently decreased with increasing
plant flow and then increased during early morning low flows.
Hourly turbidity values plotted in Figure 2 were furnished by WTP
personnel and were measured from grab samples collected at the plant
effluent. A comparison of effluent turbidity and plant flow for December
1976 is presented in Appendix E. In general effluent turbidity, agreed
with DTB observations.
The sludge blanket in clarifier //2 was always higher than the sludge
blanket in clarifier #1 during the study period. This condition indicates
an apparent imbalance between the two clarifiers. The detention times
and weir elevations were about equal, therefore the only other variable
is the return sludge collection and pumping system. Plant personnel
have checked the return sludge pumps, which were found to be pumping
properly. A major problem may be due to .the inability to increase the
34
-------
FIGURE 10
CLflRIFIER DYE STUDY
SOUTH BUFFRLO CREEK WTP
GREENSBORO, NC
CENTRQID
93 MIN
84 MIN
X OF FLOW
56
44
100
200 300 400
TIME (MIN)
600
-------
return sludge flow with increasing influent flow. Therefore, the
only alternative remaining is to increase the settling rate by
increasing the MCRT. A more turbid supernatant will result but should
create no problem for the sand filters.
Alternating the stand-by return sludge pump between the two final
clarifiers may be helpful in holding down and balancing the sludge
blankets. This could be accomplished by operating two return sludge
pumps on clarifier It 2 while operating one return sludge pump on clarifier
it1 and vice versa. Monitoring the DTB would determine the optimum
operation of the stand-by return sludge pump. The stand-by pump would
probably need to be operated only during daytime high flow. This mode
of operation may be prohibited by the tendency of aeration basins //3
and //4 to overflow during daily peak flows.
In order to efficiently control the DTB in each clarifier, a means
to measure the DTB will be required. Construction of a sludge blanket
finder is presented in Appendix H.
CHLORINE CONTACT CHAMBER
Effluent from the final clarifiers was disinfected in the chlorine
contact chamber (CCC) prior to discharge into South Buffalo Creek. In
order to meet effluent DO requirements the CCC was aerated with four
10 hp floating aerators.
Detention time in the CCC was approximately 20 minutes at the average
study flow of 12.8 mgd. The total chlorine residual ranged from 2.45 to
3.05 mg/1 based on the amperometric back titration method. During the
same period, WTP personnel measured chlorine residuals of 0.59 to
36
-------
1.32 mg/1 based on the sodium thiosulfate direct titration method.
Use of the amperometric back titration method could reduce chlorine
usage resulting in a substantital monetary savings.
SLUDGE HANDLING
A schematic diagram of sludge flow is included in Figure 1. The
majority of primary sludge was discharged directly to the vacuum filter
and subsequent incineration. Waste activated sludge was concentrated
by the air flotation unit and discharged back to the head of the plant.
Digester sludge was also filtered and incinerated.
Time did not permit an extensive evaluation of the sludge disposal
system. However sludge treatment and disposal did not appear to be a
weak link in the total wastewater treatment system.
LABORATORY
The laboratory was staffed by two laboratory technicians who
conducted the following routine analyses: BOD^, COD, TS, TVS, TSS,
settleable solids, NH^-N, TKN-N, total alkalinity, oil and grease,
fecal coliform, pH, DO, SVI, chlorine residual, temperature, and color.
One technician also spends two to three days monthly conducting a main-
tenance and testing program for a school package treatment plant.
While at the WTP various analytical procedures were discussed,
however the following observations were specifically noted:
1. In the BODc- test, effluent samples taken after chlorination
37
-------
were not being dechlorinated and seeded. The lack of
seeding on this type sample may lead to erroneously
low BOD,- results.
2. BOD,, calculations were made on samples with DO depletions
outside Standard Methods (8) recommended range of 40 to
70 percent.
3. BOD,, glassware was cleaned by using concentrated chromic
acid. The use of this reagent for cleaning purposes could
lead to toxicity problems unless a thorough rinsing program
is maintained. It is suggested that 10% H^SO^ or 10% HCL
be used instead.
4. The Iodometric direct titration method was used in deter-
mining 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 deter-
mining residual chlorine in wastewater.
5. DO samples were taken in a bucket and then poured into a
300 ml. BOD bottle with a high degree of turbulence. This
resulted in air entrapment in the sample which gives
erroneously high DO results.
The in-plant control testing program included aeration basin TSS,
DO (one depth), SVI, and BOD^ (influent). It was suggested that the
following tests also be included in their program: (1) settlometer in
place of the SVI since the settlometer better represents clarifier
38
-------
conditions; (2) clarifier sludge blanket depth; (3) aeration basin
DO at various depths and (4) centrifuge. The centrifuge test gives
a quick indication as to the solid content in the aeration basins
and whether or not the basins are receiving equal solids loading.
It was further suggested that trend charts be established and main-
tained. Useful parameters for plotting include MLSS, sludge settle-
ability, 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 param-
eters 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. It is advisable that plant
changes be made one at a time and maintained for approximately two
weeks to allow the plant to reach equilibrium.
39
-------
REFERENCES
1. McKirmey, Ross E. and Gram, Andrew. "Protozoa and Activated
Sludge", Sewage and Industrial Waste 28 (1956): 1219-1231.
2. US-EPA, Operation of Wastewater Treatment Plants, A Field Study
Training Program, Technical Training Grant No-5TTl-WP-16-03,
1970.
3. US-EPA Technology Transfer, Process Design Manual for Suspended
Solids Removal, January 1975.
4. American Society of Civil Engineers, Sewage Treatment Plant
Design, Manual of Engineering Practice No. 36, 1959.
5. Metcalf and Eddy, Inc., Wastewater Engineering, 1972.
6. West, Alfred W., Operational Control Procedures for the Activated
Sludge Process. Part I., Observations, EPA-330/9-74-001-a,
April 1973.
7. Great Lakes - Upper Mississippi River Board of State Sanitary
Engineers, Recommended Standards for Sewage Works, Revised
Edition, 1971.
8. American Public Health Association, Standard Methods for the
Examination of Water and Wastewater, 13th Edition, 1971
9. US-EPA Technology Transfer, Process Design Manual for Upgrading
Existing Wastewater Treatment Plants, October 1974.
10. Black and Veatch, Estimating Costs and Manpower Requirements for
Conventional Wastewater Treatment Facilities, October 1971.
11. Homer W. Parker, Wastewater Systems Engineering, 1975.
12. From Script for slide tape XI-43, "Dissolved Oxygen Analysis -
Activated Sludge Control Testing" , prepared by F. J. Ludzack,
NWTL, Cincinnati.
13. Alfred W. West, Operational Control Procedures for the Activated
Sludge Process, Appendix, March 1974.
40
-------
APPENDICES
-------
APPENDIX A
LABORATORY DATA
-------
appendix' 'a
LABORATORY J)ATA
SOUTH BUFFALO C?EEK '.VTP
GREENSBORO, NC
INFLUENT, PRIMARY EFFLUENT, TRICKLING FILTER EFFLUENT DRAINLINE, PLANT EFFLUENT
-------
APPENDIX A (Continued)
LABORATORY fcjATA
SOUTH BUFFALO CREEK WT?
GREENSBORO. NC
AERATION BASINS
-------
'APPENDIX A (Continued)
LABORATORY I DATA
South buffalo creek vtp
GREENSBORO. NC.
AERATION BASINS, PRIMARY SLUDGE, & .RETURN SLL'DCE
>
I
IjO
-------
APPENDIX'A (Continued)
LABORATORY dJiTA
SOUTH BUFFALO CREEK. '.TP
GREENSBORO. NC .
CLARXFIER
>
I
¦C-
i
1 01 K
i sf/a
' ik
STATION"
P
p
%
Q
<
fc>
>-
i
1 /
Ti>£ j /
V*
/ / ^ /
V / /
/
/
/////// / / / /
7/
/Hl-3
c-i
IT
'Y
7V
lOfi. | ?
-
1
t -
1
!'' i r i
i ;
/
It
/r
looo f //
-
i
1 I j 1 i
It
/r
7C.
noo 1 li
-
i
i
:
mr
11
/(¦
?<•
looo n
>i
I
1
1
!. I
i 1
i
i
i f
I J
i
1 1
-------
APPENDIX B
INFLUENT COD
SOUTH BUFFALO CREEK WTP
-------
APPENDIX B
INFLUENT COD
SOUTH BUFFALO CREEK HTP
DATE TIRE FLO«(HGD> COD L0A1K&/BAY>
12/14
900
9.6
588.
48673.
12/14
1 880
11. 8
896.
82199.
12/14
1 188
12. 8
767.
76761.
12/14
1288
12. 5
588.
61299.
12/14
1388
12. 7
558.
59182.
12/14
1 488
13. 6
647 .
73385.
1 2/14
1588
13. 3
637.
78657.
12/14
1600
13. 8
906.
184273.
12/14
1788
13. 8
652.
75848.
1 2/14
1888
13 . 6
797.
98399.
12/14
1988
13. 5
837 .
94238.
12/14
2888
13. 6
946.
187299.
12/14
2188
13. 7
2868.
327692.
12/14
2288
13. 5
1186.
124525.
12/14
2388
13. 7
1215.
138823.
12/14
2488
13. 2
772.
84988.
12/15
188
12. 7
876.
92784.
12/15
208
12. 8
787.
78763.
12/15
388
11 . 2
598.
55858.
12/15
488
18. 2
1123 .
95531.
12/15
388
9. 8
747.
56078.
12/15
680
8. 1
473.
31953.
12/15
788
8.8
478 .
31892.
1 2/15
888
8. 9
538.
39934.
AVERAGE
12.0
847
87256.
-------
APPENDIX B
INFLUENT COD
SOUTH BUFFALO CREEK ¥TP
DATE TIRE FLO« CODL> LOAB< #/DAY)
12/15
989
9.7
574.
46435.
12/15
1880
11.0
521 .
47797.
12/15
1 100
12.0
714.
71457.
12/15
1260
12.7
608.
64398.
12/15
1 300
13 . 2
1327 .
146087.
12/15
1400
14.2
878.
103980.
12/15
1500
14 . 7
927.
1 13648.
12/13
1600
15. 0
589.
73684.
12/15
1700
15. 1
820.
103266.
12/15
1800
15.0
656.
82066.
12/15
1900
14 . 9
536.
66607.
12/15
2990
14.8
524.
64678.
12/15
2180
14.7
598.
73314.
12/15
2200
14.5
637.
77032.
12/15
2300
14. 4
548.
64852.
12/15
2400
14.3
512.
61062.
12/15
100
14.0
531 .
62800.
12/16
200
13.7
550.
62842.
12/16
300
13.2
391 .
43044.
12/16
400
12. 7
598.
63339.
12/16
500
12.2
608.
61863.
12/16
600
11.8
415.
40841.
12/16
708
11.5
690.
66178.
12/16
800
11.8
1404.
138170.
AVERAGE
13 . 4
673
74943
-------
APPENDIX B
INFLUENT COD
SOUTH BUFFALO CREEK UTP
DATE TIME FLOW < HG D > CQD
12/16 909 12 6 669.
12^16 1808 13.6 446.
12/16 1188 13 9 511.
12/16 1288 14.8 538.
w
i
u>
LOftD<#/DftY)
78381.
58587.
59238
62817.
-------
APPENDIX C
GENERAL STUDY METHODS
-------
APPENDIX C
GENERAL STUDY METHODS
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 influent, primary
effluent, trickling filter effluent and final effluent streams, and
operated 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. Additional individual hourly influent samples collected over
a 52-hour period were analyzed for COD. Influent grab samples were
also taken for oil and grease.
Influent and return sludge flows were determined from plant
totalizers. Instantaneous flows of the drainage line (station DR)
were determined with bucket and watch. All dissolved oxygen measure-
ments were determined using the YSI Model 51A dissolved oxygen meter.
An Analytical Measurements Model 30 WP cordless pH recorder was installed
prior to the Parshall flume to monitor influent pH throughout the
sampling periods. Temperatures and pH were determined at other stations
with 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 (Appendix H). Sludge activity
was determined by the oxygen uptake procedure presented in Appendix F.
C-l
-------
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
(A) Turbidity of each final clarifier effluent.
Daily effluent total chlorine residual concentrations were determined
using an amperometric titrator (Fischer and Porter Model 1771010).
The procedure for the BOD^ determination deviated from Standard
Methods (8). Samples were set up and returned to Athens, Georgia in an
incubator where the analyses were completed.
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.
C-2
-------
APPENDIX D
DISSOLVED OXYGEN CONCENTRATIONS
SOUTH BUFFALO CREEK WTP
-------
APPENDIX D
SOUTH HUKf ALO »1 V
UlSSOLVtl) OXYIitN CONCtNTKAF (UiJb
STATION DATE
HASIN wl
1 -A 7b I 214
l-o 76121b
1-A 761216
l-o 76l<;i4
l-d /bi2ib
1-0 76121b
1-C 7bl2l4
1-C 76 Id lb
1-C 7bl216
HAbir. nd
2-A fbl21*
2-A 76121b
2-fi
7 h 1 d 1 fa
71> 1 ^ 14
3-t
7 6 1 ^ 1 <~
bAblN
<»-A
7 M cT U
<+-A
701*16
4-b
7bl2U
^ -hi
fbl^lb
4 -n
f b 1
1 7 . u u • b
lo.it o.J
lb.0 0.4
1 n . 0 0.2
o.d
0. i 0. 3
0.0 0.0
d.d d.ll
0.b O.b
1.J 1.4
o.7 o.b
v • 4 0.4
0.1 0.1
O.J 0.2
0.2 11.2
lb.0 1.2
lb.b O.b
lb.b 0.3
lb.0 2.U
lb.b 0.4
lb.b 0.4
lb.0 2 . b
lb.b 1.2
lb.b u.y
1.0 0.4
0.4 0.4
0.J 0.4
1,d 1 .H
0.4b 0.4
0.d 0.4
2.7 2.b
1.2 1.2
0.6 O.b
lb.b
lb.0
1«. 0
1 .b
d .6
0.6
lb.0
17.0
lb.b
0.2
1 .2
O.J
lb. 0
16.0
lb.b
0.2
1 .4
O.U
D-l
-------
APPENDIX E
TURBIDITY & FLOW RELATIONSHIP
SOUTH BUFFALO CREEK WTP
-------
APPENDIX £
HOURLY TLDW BSD TURBIDITY RERDIN03
(DEC. 70 - JON. 77)
SOUTH BUFFALO CREEK UTP
OREENSBORO. NC
289
-
138
-
IBS
-
69
-
8
-
ZBS
p
158
Z3
y_ IB2
_
Z
s~\
«—» _ _
a
53
a
>-
c
>- I
w
t—<
O
2
»—i
o
03 "•
r -J
a:
L*_
P
i—
128
S3
-
a
-
TBS
\Z3
ua
£0
I
12/6
12/0
12/7
12/B
12/S
12/10
12/11
12/12
12/13
12/14
12/15
12/10
12/17
12/18
12/19
12/20
12/21
12/20
12/27
Vv/ '/V/av/»a V V v V V'vVrfVWN V * vV,
12/2B 12/28 12/30
12/31 l/l
LtGt:',
TlC-j
T until 01 T y
.-J.-.
l/Vl'i
LiVu
,SLk/ V ^ f ^j\tAL«hV\ -S-V^-V .v .v.^ ^ .N .N,N- )
12 Rn
SUN
12 ?n
12 flfl
MO ti
\l Pfl
12 HI1
TUCS
11 Pfl
12 M
U'ED
TIME
12 PR
12 Art
THUfi
ix ph
12 BH
TRZ
12 AH
SfiT
-------
APPENDIX F
OXYGEN UPTAKE PROCEDURES
-------
APPENDIX F
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 ,
1.0 + .4 = TT4 = 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
F-l
-------
APPENDIX (Continued)
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 havi" a hip.h 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 re-
cord the DO again at 1 minute intervals until at least three
consistent readings for the change in DO per minute are ob-
tained (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 in-
dicate 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
F-2
-------
APPENDIX (Continued)
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 poi-
soned 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.
F-3
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APPENDIX G
PROJECT PERSONNEL
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APPENDIX G
PROJECT PERSONNEL
Ronald Barrow
Lavon Revells
Eddie Shollenberger
Tom Sack
Sanitary Engineer
Chemist
Technician
Technician
G-l
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APPENDIX H
SLUDGE BLANKET FINDER
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APPENDIX H
SLUDGE BLANKET FINDER (13)
Single Pole
Toggle Switch
6 Volt Battery »
w/Screw Terminals
(Use Taps or Hose Clamps
to Secure Switch and
Battery to Pole)
Distinctive 10ft Marker
1 V4tn Schedule 40
Aluminum Pipe
Distinctive 5ft Marker
Place Tape on 0 5ft
and 1.0ft Intervals
to Hold Wire and Aid
in Determining DOB
Wires to Battery
and Switch
SEE DETAIL
1 V4m Schedule 40 Aluminum
(Smaller Size May Be Used c
Short Blanket Finders)
Radiator Hose Clamp
Aluminum U-Strap
Threaded
V/4 Pipe Coupling
Radiator Hose Clamp
Threaded Site Glass Assembly
("Gitz" or Equal)
Bulb and Socket
From Cannibalized Flashlight
Epoxy Cement
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