epa 904/9-77-017
TECHNICAL ASSISTANCE PRfllECT
AT THE
VALLEY WASTEWATER TREATOT PLANT
LANGDALE, mm
£
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15®,
A
PRCfl
%
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ENVIRONMENTAL PROTECTION AGENCY
REGION IV
SURVEILLANCE AND ANALYSIS DIVISION
ATHENS, GEORGIA
FEBRUARY, 1977
i
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TECHNICAL ASSISTANCE PROJECT
AT THE
VALLEY WASTEWATER TREATMENT PLANT
LANGDALE, 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 6
Study Results and Observations 11
Flow 11
Waste Characteristics and Removal Efficiencies .... 11
Aeration Basins 16
Clarifiers 21
Chlorine Contact Chamber 22
Sludge Handling 24
Laboratory 24
References 28
Appendices
A. Laboratory Data
B. General Study Methods
C. Activated Sludge Formula Used for General Calculations
D. Dissolved Oxygen Data
E. Oxygen Uptake Procedure
F. Project Personnel
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Figures
1. Valley WTP 7
2. Influent pH - Valley WTP 15
3. Stabilization Curve - Valley WTP 18
4. Average Settlometer Results From Two
Aeration Bains Stations - Valley WTP. . .19
5. Effects of Dilution on an Aeration
Basin Settlometer Sample 20
6. Clarifier Dye Study - Valley WTP 23
Tables
I. Design Data - Valley WTP 8
II. Waste Characteristic and Removal
Efficiencies - Valley WTP 12
III. Valley WTP 20-Day BOD 14
IV. Activated Sludge Operational Parameters -
Valley WTP 16
V. Secondary Clarifier Operational Parameters
Valley WTP 21
VI. Results of Chemical Analyses on Split
Samples - Valley WTP 27
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INTRODUCTION
A technical assistance study of operation and maintenance problems
at the Valley Wastewater Treatment Plant (WTP), Langdale, Alabama 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
Enforcement and Water Divisions because of the high influent and effluent
pH (>9.0). The specific study objectives were:
1. To optimize treatment through control testing and recommended
operation and maintenance modifications;
2. To introduce and instruct 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 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 further assistance is required.
1
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The technical assistance team is appreciative for the cooperation
and assistance received from personnel of the Valley WTP,
2
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SUMMARY
The Valley Wastewater Treatment Plant (WTP) was constructed as a
4 mgd extended air activated sludge system and began operation in September
1974. It serves a population of approximately 1,600 persons and also
received the discharges from several West Point Pepperell textile mills. The
flow during the study period averaged 1.54 mgd and ranged from 0.6 to 2.2
mgd. During the study, effluent BOD5 and TSS were within the NPDES daily
average loading limitations of 1,082 and 2,154 lbs/day, respectively. The
BOD5 reduction of 97 percent was excellent, however, the TSS reduction of
76 percent was less than would be expected for a secondary treatment system.
The poor TSS removal was probably due to the excessive solids build-up in
the system. The excessive solids were the result of inadequate sludge
dewatering facilities. Listed below are some observations made during the
study:
1. Sludge disposal was the major problem. This was caused by
inadequate drying space and a slow dewatering sludge.
2. During the study, no sludge was wasted, and an average of 2.5 mgd
of sludge was returned daily (approximately 162 percent of the
plant flow).
3. The WTP's influent pH was extremely high (10.0 to 11.6 pH units).
If the pH is maintained at 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 below 8.0, large amounts of
metals in the sludge could be released and cause harm to the
treatment plant and stream biota (14).
4. Hydraulic detention times for the two final clarifiers were different
3
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(135 and 159 minutes) indicating an uneven flow split.
5. The laboratory was well equipped and adequate laboratory records
were maintained. However, there was a shortage of laboratory space
and staffing.
6. The average percent difference in split sample results between
EPA and Valley WTP for BOD^, TS, and TVS were greater than Standard
Method's precision data for the same test. However, the average
percent difference for the TSS and VSS test were in agreement with
Standard Method's precision data.
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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.
1. TSS removal efficiency would improve if sludge age and MCRT was
decreased. This points up the major problem which is the inability
to adequately dewater solids. Additional drying beds or other
dewatering facilities are essential for proper operation of the
fac.i lity.
2. The cause for the difference in the hydraulic detention times
between the two final clarifiers should be determined and corrected.
3. BOD5 samples should be neutralized and dechlorinated.
A. Only those samples with DO depletions between 40 and 70 percent
should be used in BOD^ calculations.
5. A Standard Method's back-titration method should be used for
determining residual chlorine in wastewater.
6. Operational control testing and trend charts should be used to
optimize WTP process control.
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TREATMENT FACILITY
TREATMENT PROCESSES
A schematic diagram of the Valley WTP, Langdale, Alabama is presented
in Figure 1, and design data are enumerated in Table I. The WTP was designed
as a 4 mgd extended air activated sludge system, serving a population of
1,600 and wastewater discharges from several West Point Pepperell textile
mills. The facility began operation in September 1974.
Raw wastewater entered the WTP via three force mains and was introduced
immediately into the aeration basin. In the aeration basin, the wastewater
was aerated and mixed by eight 75 hp fixed aerators operated on a staggered
schedule. From the aeration basin mixed liquor flowed into two center-fed
clarifiers equipped with surface skimmers and sludge collection devices.
Clarifier sludge was returned to the aeration basin by three 15 hp pumps
and was reintroduced at the number six aerator. A valve, located on the
return sludge line, can direct up to 100 percent sludge to either the digester
or the aeration basin.
Sludge was digested in an aerobic digester equipped with two 75 hp
mechanical aerators. The digested sludge was applied to four drying beds.
The digester supernatant mid drying bed drainage was pumped to the aeration
h.isin ,in
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FIGURE I
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TYPE
Flow Measurements
Influent
Effluent
Return Sludge
Average Flow
Design Flow
Aeration Basin
Number
Length
Width
Depth
Surface Area
Volume
Detention Time
Aeration
Final Clarifier
Number and Type
Diameter
Depth (SWD)
Surface Area (each)
Volume (each)
Detention Time
Chlorine Contact Chamber
Number and Type
Length
Width
Depth
Volume
Detention Time
TABLE I
DESIGN DATA
VALLEY WTP
LANGDALE, ALABAMA
EXTENDED AIR
4 ft. rectangular weir
18 inch Parshall flume, recorder,
totalizer
Magnetic flow meter
1.54 mgd (study period)
4 mgd
1 Trapazodial
638 ft.
250 ft.
14.5 ft.
159,500 sq. ft.
1,591,000 cu. ft. (11,900,000 gals.)
3 days
8 - 75 hp Stationary Mechanical
Aerators
2 circular
65 ft.
10 ft.
3,317 sq. ft.
33,166 cu. ft. (248,100 gals.)
1.48 hrs.
1 - rectangular
46 ft.
38.5 ft.
6 ft.
10,027 cu. ft. (75,000 gals.)
27 min.
8
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TABLE I (cont)
Digestor
Number nnd Type
Length
Width
Depth
Volume
Aeration
1 aerobic, Trapazodial
150 ft.
97 ft.
10 ft.
92,246 cu. ft. (690,000 gals.)
2 - 75 hp Floating Aerators
Drying Beds
Number and Type
Length
Width
Area (each)
Volume (each - assuming a 1 ft. depth
4 - Rectangular
100 ft.
25 ft.
2,500 sq. ft.
2,500 cu. ft. (18,700 gals.)
9
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Of the five operators only two were certified. The chief operator who
doubled as the laboratory technician was certified as a grade 3, and one
other shift operator was certified as a grade 2. Uncertified operators are
presently attending certification classes.
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STUDY RESULTS AND OBSERVATIONS
A complete listing of all analytical data and general study methods
are presented in Appendices A through E. Significant results and observations
made during the study are discussed in the following sections.
FLOW
A four foot rectangular weir with totalizer and strip recorder was
constructed to measure influent flow. However, during the study this flow
measuring device was inoperable. Effluent wastewater flow was measured by
an 18 inch Parshall flume with totalizer and strip recorder, which
was Located between the final clarifiers and chlorine contact chamber.
Average plant flow during the study period (Table I) was 1.54 mgd and ranged
from 0.6 to 2.2 mgd.
Return sludge flow rates were measured by a magnetic flowmeter. An average
of 2.5 mgd of sludge was returned daily, which was approximately 162 percent
of the effluent flow. No sludge was intentionally wasted during the study
period. Waste sludge flow from the clarifier was controlled by a pneumatic
valve located in the return sludge line. This valve directed sludge flow to
either the digester or the aeration basin. Waste sludge flow to the
digester can only be determined by calculations using pumping time and
pump capacities.
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
A chemical description of the Valley WTP influent and effluent wastewaters
with calculated treatment reductions are presented in Table II. Analyses
were conducted on 24-hour, flow porportional, composite samples, collected
on three consecutive days during the study period; and percent reductions
were calculated from the averaged results.
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TABLE II
WASTE CHARACTERISTICS AND REMOVAL EFFICIENCIES
VALLEY WTP
PARAMETER INFLUENT EFFLUENT REDUCTION
(mg/1)
(mg/1)
(%)
BOD5
533
18
97
COD
1440
278
81
TOC
497
89
82
TS
2195
1189
46
TVS
835
270
68
TSS
153
36
76
VSS
115
22
81
TKN-N
12.7
2.4
81
NH3-N
2.45
0.37
85
N03-N02-N
0.83
0.02
98
TOTAL PHOSPHORUS 3.9
2.3
41
Pb
<0.05
<0.05
-
Cr
<0.05
<0.05
-
Cd
<0.01
<0.01
-
Cu
0.084
0.122
-45
Zn
0.176
0.103
41
Ni
<0.05
<0.05
The average
composite influent BOD5
(533 mg/1).
COD (1440 mg/1)
TOC (497 mg/1) concentrations represented a strong waste which might be
expected with the high percentage (75%) of industrial wastewater discharged
into the plant. The TSS (153 mg/1) concentration was at a level typically
found in pure domestic waste (5).
The average composite effluent BOD^ and TSS concentrations were 18 and
36 mg/1 with 97 and 76 percent reductions, respectively. Based on these
concentrations and a 1.54 mgd average flow, both the effluent BOD5 and TSS
were within the NPDES daily average loading limitations of 1,082 and 2,154
lbs/day, respectively. However, the TSS concentration and percent reduction
was less than would be expected for a secondary treatment system.
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As shown in Table II, the TKN-N, NO3-NO2-N and NH3-N concentrations
were reduced within the waste treatment system by 81, 98, and 85 percent,
respectively. The organic-N portion of the TKN was probably converted to
NH3-N. Since the pH of the wastewater within the system was usually greater
than 9.5, most of the converted NH3 and the. influent NH3-N was air stripped
out of the system. The NO3-NO2-N was probably assimilated by the mixed
liquor organisms.
Table III presents the 20-day BOD values for the Valley WTP influent and
effluent. Analyses were conducted on 24-hour, flow proportional composite
samples, collected on February 15-16, and February 16-17, 1977. The
influent BOD20 values for the two day period were 1,020 and 1,400 mg/1,
and the effluent BOD20 values were 85 and 90 mg/1, respectively. The
effluent BOD5 values for the same samples of 28 and 12 mg/1, represent 33
arid 13 percent, respectively, of the BOD20. It is interesting to note
that the oxygen consumption rate increased significantly after about 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 some organic compound or compounds being
broken down to a biologically usable state.
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TABLE ITI
VA1,1.1'lY WTP 20-HAY HOD
J.NKLUENT (2/16/77) 1NKIAJENT (2/17/77)
DAY TOTAL BOD (mg/1) DAY TOTAL BOD (mg/1)
21 hr. 165
5 510 5 590
6 550 6 640
7 570 8 720
9 665 11 780
12 695 14 820
15 682 20 1400
20 1020
EFFLUENT (2/16/77) EFFLUENT (2/17/77)
DAY TOTAL BOD (mg/1) DAY TOTAL BOD (mg/1)
21. hr. 2
5 28 5 ] 2
h 3H 6 15
7 39 8 23
9 45 11 34
12 53 14 50
15 60 20 90
20 85
The influent ratio of BOD5 to nitrogen to phosphorus was calculated at
100: 2.54: 0.73. As compared to the recommended ratio of 100: 5.0: 1.7, the
raw waste was considered to be limited in both nitrogen and phosphorus (9).
rnfluent: pH was monLtored continuously from 1:00 a.m. February 15, to
12:00 p.m., February 17, 1977. These results are depicted in Figure 2- The
pU values ranged from 10.0 to 11.6 which Ls a strong indication of tlie effect
the industrial discharge has on the waste treatment system. Within the aeratio
basin the pH was reduced to 8.0 with a final effluent recording between 7.8
and 8.0.
NOTE: Most metals, except mercury and chromates^ are precipitated as
hydroxides, provided the pH is maintained at 8.0 or above, and become
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pH
12
8
4
12
8
4
12
8
4
12
8 f—
4
FIGURE 2
INFLUENT pH
VALLEY WTP
02/I4/77-M0N.
__ 02/15/77-TUE,
02/16/77-WED.
02/17/77-THUR.
1
12
6
A.M.
TIME (Hours)
6
P.M.
-------
incorporated In the sludge. If the pH should fall below 8.0, large
amounts of metals in the sludge could be released and cause great
harm to the treatment plant and stream biota (14).
AERATION BASIN
Grab samples were collected at the effluent end of the aeration basin
and analyzed for total suspended solids (TSS), volatile suspended solids
(VSS), percent solids by centrifuge, and settleability as determined by the
settlometer. Presented in Table IV are various calculated activated sludge
operational parameters and recommended design values from the literature.
Calculated loading parameters in Table IV indicate that the system was
operating near 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. The high
MCRT can be attributed to the lack of sludge wasting during the study.
TABLE IV
ACTIVATED SLUDGE OPERATIONAL PARAMETERS
VALLEY WTP
MEASURED
RECOMMENDED(2)(5)(7)
MLSS (nig/I)
MLVSS (mg/I)
HYDRAULIC DETENTION TIME (lirs)
MEAN CELL RESIDENCE TIME (dnys)
SLUDGE AGE (days)
LBS B0D5/day/lb MLVSS (F/M)
LBS COD/day/lb MLVSS
LBS BOD5/day/l,000 cu.ft.
4118
3450
70.8
924*
208
0.02
0.054
0.05 - 0.15
0.2
10 - 25
3000 - 6000
18 - 36
20 - 30
>10
OF AERATION BASIN
RETURN SLUDGE RATE (% of
4.3
50 - 200
AVERAGE PLANT FLOW)
162
* During the study week there was no sludge wasting
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Oxygen uptake rates are indicators of sludge activity and of effluent
quaJity. The oxygen uptake rate or load ratio is the measure of oxygen
depletion before and after the introduction of raw waste.
T , _. DO/min fed sludge
Load ratio = —-—
DO/min unfed sludge
The oxygen uptake procedure is presented in Appendix E. The unfed
oxygen uptake rate (URS) was 0.09 mg/l/min. This oxygen uptake rate was
extremely low when compared to the 0.5 mg/l/minute rate recommended for
domestic waste treatment at a MLSS concentration of 2,500 - 3,500 mg/1.
However, considering the ratio of industrial waste, pH, solids concentration
and the degree of WTP performance, it was determined that the low uptake
rate was characteristic of the system.
A minimum fed (FRS) oxygen uptake rate for domestic waste treatment
should measure 1.0 mg/l/min or greater. Both the pH adjusted and the
unadjusted raw waste test samples had uptake rates of 0.40 and 0.27 mg/l/min.,
respectively. This uptake rate was less than a normal unfed rate and was
probably a reflection of the low unfed rate.
It is apparent from the aeration basin detention time (70.8 hrs.) and
the stabilization time (27 hrs.) that the sludge had reached stabilization
many hours before being removed from the aeration system. Figure 3 shows
an increase in activity for the pH adjusted sample as opposed to the
unadjusted sample, which indicates the effect of the pH on the sludge
activity rate.
Presented in Figures 4 and 5 are settleability curves for the activated
sludge as determined by the settlometer. The upper curve, Figure 5,
represents the unaltered settling rate of mixed liquor from the aeration
basin to the clarifier. The middle and bottom curves are 75 and 50 percent
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oo
FIGURE 3
STABILIZATION CURVE
VALLEY WTP
pH Unadjusted-9.5
¦ApH Adjusted-7.8
o.i Jr-
SLUDGE ACTIVITY RATE
I I I U j.
I I I I I
20 21 22 23 24 25 26 27
TIME (Hours)
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AVERAGE
TWO
100
UJ
Z>
75
_J
o
>
UJ
e>
50
Q
z>
1
cn
o
UJ
25
1
h-
1—
UJ
CO
0
FIGURE 4
SETTLOMETER RESULTS FROM
AERATION BASIN STATIONS
VALLEY WTP
¦a VA-1
¦* VA-2
1
20 30 40
TIME (Min.)
50
60
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FIGURE 5
EFFECT OF DILUTION ON AN
AERATED BASIN SETTLOMETER SAMPLE
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dilutions which show a rapid dropping out of solids. This indicates there
is no tendency toward a bulking sludge.
These data in combination indicate a need to decrease the solid
concentration in the aeration basin and to decrease the MCRT and sludge age.
CLARIFIERS
Two circular center feed Eimco clarifiers with skimmers are utilized
for final settling. A problem with floating solids in both clarifiers was
observed as both clarifier inner receiving rings were completely filled
with floating dried solids. IL is necessary for plant personnel to hand
clean this area to dispose of these accumulated solids. Also, a floating
scum covered approximately 75 percent of the clarifier surface, which
contributed to the level of suspended solids in the effluent. This problem
was attributed to the scum rake being installed incorrectly. This
installation was corrected a few days prior to the study and is expected to
correct the problem.
Table V presents the actual and recommended parameters for final
clarifiers of an extended aeration activated sludge system. The calculated
values were based on the average plant flow (1.54 mgd) and return sludge
(2.5 mgd) using formulae presented in Appendix C. All of the parameters
are within acceptable limits for the present wastewater flow.
TABLE V
SECONDARY CLARIFIER OPERATIONAL PARAMETERS
VALLEY WTP
ACTUAL
RECOMMENDED (4)(7)(9)
Hydraulic Loading (gpd/sq. ft.)
Solids Loading (Ibs/day/sq.ft.)
Weir Overflow Rate (gpd/lin.ft.)
Hydraulic Detention Time (hrs)
232
20
3,775
2.94
<15,000
2-3
400 - 800
20 - 30
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The return sludge rate of 2.5 mgd (.162% of effluent flow) maintained
sludge blanket depths of 3.5 to h ft. in both clarifiers throughout the
study. Maintaining this level wl 1 L reduce the posn l.lvi 1.1 ty of a hydraulic
washout of sludge.
A dye study on the clarifiers was conducted to determine the detention
t Line of the units. A volume of Rhodamine B dye (500 mis) was applied to
each clarifier and grab samples of the clarifier effluent were taken at
timed intervals for a three hour period. These samples were tested for
fluoresence and the results are plotted in Figure 6. The first visible
discharge of dye over the clarifier weirs occurred 14 minutes after
application. The dye discharge peaked at 23 and 28 minutes from clarifiers
1. and 2, respectively. The hydraulic detention times were determined as
the centroid of the curves for clarifiers //I and #2, which were 135 and
159 minutes, respectively. The dye study detention times for both
clarifiers was less than the calculated value of 176 minutes.
There was always a small amount of suspended solids observed in the
clarifier effluent. These solids averaged 36 ppm or 462 lbs/day.
CHLORINE CONTACT CHAMBER
Chlorine was applied at the effluent Parshall flume at a rate of
75 lb/day producing a chlorine residual of 0.15 to 0.3 mg/1 during the
study. After traveling a short distance, the chlorinated wastewater
stream entered the contact chamber which had a designed detention time of
27 minutes.
Sludge had settled throughout the contact chamber with the heaviest
accumulation in the approach area of the effluent pipe. This accumulated
sludge reduced the effective detention time of the chamber. Also, bubbles
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FIGURE 6
CLARIFIER DYE STUDY
VALLEY WTP
Clarifier Centroid % of flow
o I 135 Min. 37
a 2 159 Min. 63
100
200 300 400
TIME (Min.)
500
600
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were observed rising to the surface of the wastewater in the: chamber whLch
Indicated the .sludge had become septic and would exert nn oxygen demand
on the receiving stream. Aeration of the effluent stream at the Parshall
flume and in the pipe discharging to the contact chamber produced a white
foam that covered approximately one-fourth of the chamber surface area.
SLUDGE HANDLING
Sludge was digested in 690,000 gallon aerobic digester equipped with
two 75 hp floating aerators. After digestion, the aerators are shut down
and the sludge is allowed to settle. The supernatant is pumped to the
aeration basin and the settled sludge is allowed to flow by gravity into
four 25,000 cu.ft. drying beds.
Even though the suspended solids concentration (16,700 mg/l-study average)
was high, dissolved oxygen concentrations were maintained at an adequate
level for sludge digestion.
Sludge disposal was a problem at the WTP. This was caused by inadequate
drying space and a slow dewatering sludge.
LABORATORY
The Valley WTP laboratory is located in the main control building.
The chief operator conducts the routine analyses which includes: BOD5, TS,
TVS, TSS, VSS, DO, pH, temperature, residual chlorine, and fecal coliform.
The laboratory was clean and neat, and had adequate equipment for the analyses
performed. Adequate records were also kept on the analytical data. However,
there did not appear to be sufficient laboratory space and staffing.
While at the WTP various analytical procedures were discussed, however
the following observations were specifically noted:
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1. Effluent BOD5 samples which had a chlorine residual and a pH
above 9.0 were not being dechlorinated or neutralized. Influent
samples which also had a high pH (>9.0) were not being neutralized.
Both chlorine and high pH are toxic to the organism that exert
BOD^ and could cause erroneously low BOD5 results.
2. Some BOD5 calculations were made on samples with DO depletion
outside the Standard Methods (8) recommended range of 40 to 70
percent.
3. The amperometric direct titration method was used in determining
chlorine residual. The determination of residual chlorine in
samples containing organic matter present special problems, therefore
Standard Methods (8) recommends a back titration method for
determining residual chlorine in wastewater.
4. In the VSS analysis, aeration basin and return sludge samples were
filtered using a glass fiber filter paper and a Buchner funnel.
The filter paper with samples were then placed, one at a time, at
an angle in a pre-heated muffle furnace. The samples were left
In the furnace until they* reach constant weight. The analyst
encountered a problem of floating ash from the samples during the
ignition stage. It was suggested that the samples be filtered
using the gooch crucible technique and placed in the muffle
furnace and the rest of the VSS procedure followed.
The in-plant control testing program included aeration basin TS, TSS,
VSS, DO (Surface), pH (Surface), and SVI; digester pH, DO, TS, and VSS; and
return sludge pH, DO, and TSS. It was suggested that the following tests
25
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also be included in their program: (1) settlometer in place of the SVI
since the settlometer better represents clarifier 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 aertation basin 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 trends so that gradual changes in plant conditions can be
detected prior to deterioration in effluent quality.
Four 24-hour composite samples taken on February 15-16, and February
16-17, 1977 were split between EPA and Valley WTP personnel. The results
of the analyses are given in Table VI. The average percent difference between
EPA and Valley WTP results for BOD5, TS, TVS, TSS, and VSS was 27, 5.8, 14.7,
24.8, and 26.8 percent, respectively. Standard Methods gives precision
data for the above tests of BOD^ (15%), TVS (6.5%),TSS (0.76 to 33%), and
VSS (0.76 to 33%).
26
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TABLE VI
RESULTS OF CHEMICAL ANALYSES ON SPLIT SAMPLES
STATION
DATE
BOD 5
EPA WTP*
TS
EPA WTP
PARAMETER (mfi/1)
TVS
EPA WTP
TSS
VSS
EPA
WTP
EPA
WTP
VI
VE
VI
VE
2/15-16/77
2/16-17/77
2/15-16/77
2/16-17/77
510
28
590
12
483
7
576
9
2246 2294 808 690 204 135 148 105
1155 1208 284 196 38 45 20 30
1857 2038 878 890 140 175 108 100
1192 1268 249 220 32 25 19 15
* Valley WTP
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1
2,
3,
4,
5.
6
7
8
9
10
11
12
13
14
REFERENCES
McKinney, Ross E. and Cram, 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 Assiciation, Standard Methods for the Examination
of Water and Wastewater, 13th Edition,
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 1974.
EPA Technology Transfer, Wastewater Treatment Systems-Upgrading Textile
Operations to Reduce Pollution, October 1974.
28
-------
APPENDICES
-------
APPENDIX A
LABORATORY DATA
-------
APPENDIX A
LABORATORY 'DATA
VLLEY VTPy LASGDAi.E. ALASKA
IKFLUDTT, ZFTUJZHT, RETURN SLL'DGE, AND AEROBIC DIGESTS
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-------
APPENDIX; A
laboratory data
VALLEY WTfr LAWCDALE. ALABAMA
A£RATION BASIN ASV AEKOSIC DIGESTERS
JSV
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-------
appemdix a
LABORATORY DATA
ALLEY WTP, LANGDALE ALABAMA
CLARIFIERS
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-------
APPENDIX B
GENERAL STUDY METHODS
-------
APPENDIX B
GENERAL STUDY METHODS
VALLEY 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 influent, and effluent streams and
operated three consecutive 24-hour periods. Aliquots of samples were pumped
at hourly intervals into individual refrigerated glass bottles which were
pumped at hourly intervals into individual refrigerated glass bottles
which were composited proportional to flow at the end of each sampling
period.
Effluent flow was determined from plant totalizer. Pump capacity
and pumping times were (station DR) used to determine return sludge flow.
All dissolved oxygen levels were determined using the YSI Model 51A
dissolved oxygen meter.
An Analytical. Measurements Model 30 WP cordless pH recorder was
installed on the influent receiving box 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 (13).
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:
B-l
-------
(.1) Settleability of mixed liquor suspended solids (MLSS) as
determined by the settlometer test;
(2) Percent ho] ids of the mixed liquor and return sludge determined
by centrifuge;
(3) Suspended Solids and Volatile Suspended Solids analyses on the
aeration basin mixed liquor and return sludge;
(A) Turbidity of each final clarifier effluent.
Daily effluent chlorine concentrations were determined using an
nmpermetrIc tltrator (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-mine 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 recommend.it ion for use by the Environmental Protection Agency.
B-2
-------
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/l
(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 daily values) = mg/l
Aeration Basin Vol. = m.g.
TSS, Primary Eff. or Basin Inf. conc. = rag/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/l
(%, 30 min. set, solids) x (10,000)
MLSS
5. Sludge Density Index (SDI)
SVI 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/l
Basins Inf. COD conc. (avg. or daily value) = mg/l
Plant Flow = mgd
MLVSS conc. (avg. or daily value, note Volatile SS) = mg/l
Basin Vol. = m.g.
(BODs conc.)x (plant flow) x (8.34) = lbs. BOD/lb. MLVSS
(MLVSS) x (Basin Vol.) x 8.34
C-l
-------
(COD conc.) x (plant: flow) x (8.34
(MLVSS) x (Basin Vol.) x (8,34) = lbs- COD/]b. MLVSS
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 = rag/1
Plant flow = mgd
(MLSS) x (Basin vol. + Clarifier vol,) x 8.34
(Waste activated sludge conc.) x (waste flow) x 8.34 4- ~ days
(Plant effl. TSS x plant flow x 8.34)
Clarif ier
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/lin . ft.)
Weir Lenght = ft.
Plant flow to clarifier = gal./day
—f 1 ° w _ = gal./day/lin.ft.
Wc ir length
C-2
-------
APPENDIX D
DISSOLVED OXYGEN DATA
-------
APPENDIX D
VALLEY WTP
DISSOLVED OXYGEN CONCENTRATIONS
08 H 6 04 H2 fi Effluent
I
i
H 7
0 5
H 3
8 1 n
Effluent
i n
>
Influentf
¦STATION
DATE
TEMP
DO-mg/1
DO-mg/1
DO-mg/1
DO-mg/I
CENT
1 ft.
5 ft.
10 ft.
Bottom
1
2/15/77
16°
7.4
7.0
7.0
7.1
2
2/15/77
16°
7.4
7.0
-
7.1
3
2/15/77
16°
6.2
6.0
5.9
-
4
2/15/77
16°
4.8
3.7
-
3.1
5
2/15/77
16°
2. 2
1.6
1.2
0.1
6
2/15/77
16°
3.6
3.4
-
3.4
7
2/15/77
16°
1.9
1.3
1.4
1.5
£
2/15/77
16°
3.4
3.4
3.4
—
KEY: 8
Mechanical
Aerator
(Operating)
0
Mechanical
Aerator
(Not operating)
-------
APPENDIX E
OXYGEN UPTAKE PROCEDURE
-------
APPENDIX E
OXYGEN UPTAKE PROCEDURE IV
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. 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 _
1.0 + .4 ~ 86 ml
3. Carefully add final clarifier overflow to fill the BOD bottle and
to dilute the return sludge to the plant aerator mixed liquor solids
concentration.
4. Connect the filled bottle and an empty BOD bottle with the BOD
bottle adapter. Invert the combination and shake vigorously,
while transferring the contents. Re-invert and shake again while
E-l
-------
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 BO again at 1 minute intervals until at least three consistent
readings for the change in DO per minute are obtained (ADO/inin).
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 l.R Lntlicute.s that something in the wastewater shocked or poisoned
the. "bugs".
E-2
-------
Taken from "Dissolved Oxygen Testing Procedure, "F.J. Ludzack and
script for slide tape XT-A3 (Dissolved Oxygen Analysis - Activated
Sludge Control Testing) prepared by F.J. Ludzack, NF4RC, Cincinnati.
-------
APPENDIX F
PROJECT PERSONNEL
-------
APPENDIX p
PROJECT PERSONNEL
CHARLES SWEATT
LAVON REVELLS
TOM SACK
EDDIE SHOLLENBERGER
CAROLYN STROUP
SANITARY ENGINEER
CHEMIST
TECHNICIAN
TECHNICIAN
STUDENT TRAINEE (CO-OP)
F-l
------- |