\\l
United States
Environmental Protection
Agency
Risk Reduction Engineering
Laboratory
Cincinnati OH 45268
Research and Development
EPA/600/S2-89/003 Feb. 1990
&ER& Project Summary
Capital and O&M Cost
Estimates for Attached
Growth Biological Wastewater
Treatment Processes
Henry H. Benjes, Jr.
Data for projecting process
capabilities of attached growth
biological wastewater treatment
systems and procedures for making
design calculations are presented in
this report. Carbonaceous oxidation
(secondary treatment) and single-
stage nitrification design examples
are given. Information for estimating
average construction costs and
operation and maintenance (O&M)
requirements are presented for
typical wastewater treatment plants
ranging in size from 1 to 100 mgd
capacity.
Estimated average construction
costs and O&M requirements for
individual unit processes are related
graphically to appropriate single
parameters for each component.
Construction costs are broken down
into labor and materials components
to enable the costs to be inflated
using readily available Bureau of
Labor Statistics Wholesale Price
Indices. O&M requirements are given
for labor, energy, and maintenance
materials and supplies so that
appropriate current, local unit costs
can be used to estimate annual
costs.
The data in this report provide a
means for estimating anticipated
average performance and costs for
facilities, but they should not be
substituted for detailed assessment
of local conditions or recognition of
changing design requirements.
This Project Summary was
developed by EPA's Risk Reduction
Engineering Laboratory, Cincinnati,
OH, to announce key findings of the
research project that Is fully
documented In a separate report of
the same title (see Project Report
ordering Information at back).
Introduction
This report represents recommended
design procedures, reviews performance
design procedures, reviews performance
capabilities, and presents cost estimating
guidelines for municipal wastewater
treatment plants incorporating attached
growth biological processes for
secondary treatment. Attached growth
treatment processes are based on the
development of biological growth on a
media surface, either by passing
wastewater over stationary media or by
moving media through a wastewater bath.
Attached growth processes are most
commonly exemplified by the trickling
filter. The rock media trickling filter has
been recognized and used since 1898.
There are nearly 4,000 municipal trickling
filter wastewater treatment plans in the
United States.
Objectives
The objectives of this report are to
develop suggested design procedures for
attached growth biological treatment
processes, assess the accuracy of those
procedures, and present guidelines for
-------
estimating capital costs and O&M
requirements.
Commonly used design procedures for
biological treatment processes are
empirical in nature, based on
experienced results. Available design
procedures are reviewed to assess their
utility in assisting the engineer in
predicting attached growth performance.
Once a design has been developed
and the proposed facilities sized,
estimating capital costs and O&M
requirements must be considered.
Capital costs include the cost of
construction; engineering, legal, and
administrative services; land; and interest
during construction. This report
emphasizes the development of
construction costs. Other costs, except
land, may be related to construction
costs. Land is a variable that cannot be
typified. General information for plant
construction costs has been available for
some time; however, this information is
often presented for an overall system,
rather than in terms of unit processes.
The variability of combinations of several
unit processes limits the use of these
data. By separating plant costs into
categories of unit processes, historical
cost data from existing plants may be
applied to similar processes in project
planning.
Attached Growth Processes
Considered
Four attached growth processes are
examined in the report, including rock
media trickling filters, plastic media
trickling filters, rotating biological
contactors, and trickling filter/solids
contact, which is an attached growth
process enhanced by a coupled-
suspended growth process. The six
process alternatives analyzed in the
study are listed in Table 1. These
processes are generally incorporated into
liquid stream system designs that include
pretreatment via screening and grit
removal, primary and final sedimentation,
sludge pumping, recirculation pumping,
and effluent disinfection. Sludge handling
selection varies depending on local
economic considerations.
• Rock media trickling filters are a
simple, single-stage treatment process.
Rock media varies in diameter from 1
to 4 in. and are designed with depths
of 3 to 10 ft. Wastewater is
continuously sprayed over the
stationary media, which supports
biological growth. Treated wastewater
is collected in a underdrain system
where it is recycled and/or directed to
the final settler. Biological growth
sloughs from the media resulting in the
need for final sedimentation. Rock
media filters are usually employed for
secondary treatment (carbonaceous
removal) only.
• Plastic media trickling filters were
introduced to overcome the limitations
of rock media. Plastic media trickling
filters may be designed much deeper
(commonly 21 ft deep) than rock filters
since the media is very light.
Corrugated sheet modules are
delivered in bundles that are then cut
to size and placed in the media towers.
Plastic rings, on the other hand, are
dumped, making installation simple.
Recirculation is typically taken
directly from the trickling filter
underflow, although some designs
recycle the final sedimentation tank
underflow. Plastic media have been
used for both carbonaceous removal
and nitrification.
• Rotating biological contactors (RBC's)
were developed in Europe and
introduced in the United States in the
1970's. The media, which supports
biological growth, is generally 12 ft in
diameter and rotated through a bath of
wastewater. The media is alternately
exposed to the liquid and to the
atmosphere. RBC effluent is typically
not recirculated. Originally, the media
was designed as a series of closely-
spaced, parallel, flat discs with a
specific surface area of 20 to 25 ft2/ft3.
The newer lattice-structured media
Table f. Biological Treatment Process Alternatives
Treatment Process
offers about 50% more specific si
area than the disc-type constru
The lattice-structured media, and
lesser extent the disc structure
fragile and should be protected
direct exposure to sun, wind,
weather. Therefore, the medii
enclosed in either superstructu
individual shaft covers. Media re
can be provided by either mecri
drives or air motivation. RBC's m
used for either secondary treatm
secondary treatment plus nitrifi
applications.
Trickling fitter/solids contact (TFI
a development that enhance
reliability of the trickling filt
incorporating suspended g
treatment in the process. There
been other "coupled" atti
growth/suspended growth pro<
that have been used in an atte
offset the disadvantages assc
with the two processes. Wil
processes there can be
variations in relative organic I
rates, locations and quantit
recycle, and process arrangem
a consequence, there were an i
process alternatives under the
category of "coupled tri
filter/suspended growth" proce;
TF/SC variation represents
processes in this report.
The TF/SC process uses the
filter (TF) as the primary me
remove organics and a ven
hydraulic retention time aeratic
(SC) to polish that tricklin
effluent. Where the treat me
effluent quality needs only t
secondary treatment stand;
conventional final sedimentatic
is used. Where higher quality
standards are required,
sedimentation basin with a flo<
center well is used. The TF/SC
is not used for nitrification.
nitrification is required, the
segment must be larger ;
process is no longer categori;
TF/SC process.
Carbonaceous Removal Only
Single-Stage Carb. Rem
Nitrification
Rock Media Trickling Filter
Plastic Media Trickling Filter
RBC's
TricUing Filter/Solids Contact
-------
ocedure
i three-step approach was used to
nduct the work of this study. The first
p was to develop design criteria for
atment plant liquid and solids handling
it processes applicable to attached
iwth treatment systems. To thoroughly
aluate a complete treatment system
ernative, it is necessary to consider the
sign and costs of ancillary treatment
its, such as solids handling processes
d functional parts of the total project.
tailed construction costs and O&M
}uirements for typical additional unit
ocesses and functional units that
mplete the system alternatives are
:luded.
The second step was to collect,
alyze, and formulate the construction
st and O&M requirements for each unit
ocess. Comparative cost information is
esented for certain design
odifications, e.g., alternative solids
ocessing equipment.
The third step was to develop flow
agrams for each of the systems.
pical flow schemes meeting the state
rformance requirements have been
eluded.
The attached growth processes
timated have been sized to correspond
design flows ranging from 1 to 100
gd. Within this range, six nominal plant
pacities have been evaluated: 1, 5, 10,
, 50, and 100 mgd.
The following unit process costs have
en included in the complete final
sport:
law wastewater pumping
'.hlorine feed & storage facilities
Derated grit removal & flow measurement
>O2 storage & feed equipment
'rimary treatment screens
lotation sludge thickeners
edimentation basins
ludge handling tanks
Sludge pumping stations
Anaerobic digesters
Trickling filters
Filter presses
Rotating biological contactors
Centrifuges
Inplant & recycle pumping stations
Multiple hearth incinerators
Aeration basins
Sludge & ash lagoons
Mechanical aeration equipment
Land spreading of sludge
Blowers
Sand drying beds
Diffused air aeration equipment
Sludge composting
Effluent filtration
Pipeline transport
Chlorine contact basins
Truck transport
The costs have been presented in two
forms. The construction cost components
have been itemized for several sizes of
the unit process so they can be updated
according to the inflation rates for the
individual components. The total updated
costs (September 1987) are also
presented graphically so they can be
used for any size treatment system. Total
annual costs (September 1987) for the
different size plants and treatment
options are summarized.
These costs, presented in terms of
$/1,000 gal wastewater treated, are the
sum of a plant's annual O&M costs and
its capital costs amortized for 20 yr at
10% divided by the total quantity of
wastewater treatment annually.
The most cost-effective treatment
method is indicated in Table 2. RBC's are
estimated to be the most economical
attached growth process for
carbonaceous oxidation and for single-
stage nitrification. The estimated costs for
the TF/SC process are essentially the
same as for the RBC process above 10
mgd. The relative ranking of these costs
for estimating purposes should be
tempered by site-specific conditions and
by engineering judgment. The use of
these cost estimating procedures results
in project estimates that are very close to
the experienced costs to as much as
30% different than experienced costs.
The relative accuracy, comparing
competing alternatives should be within
10%.
Design Approaches
Performance data from operating
systems are used to evaluate the various
methods for designing attached growth
processes. This is particularly important
since design must be based on achieving
specific effluent quality. The design
approaches for removal in rock and
plastic media trickling filters and RBC's
are evaluated first, followed by
performance evaluation and the design
approach for the TF/SC process
Attached growth processes are
characterized by a decreasing
concentration of organics passing over a
film of attached bacterial growth. Organic
and oxygen fluxes from the carriage
water to the growth are proportional to
their concentrations. The surface area is
the major parameter in attached growth
process evaluation if the organic loading
rate is not so high that either the rate of
organic assimilation by bacteria or the
rate of oxygen transfer would limit the
removal rate. Greater surface area per
unit volume will support more bacterial
growth and provide more contact
opportunities between organics and
bacteria. However, there are many
complicating factors that obviate the
effect of media surface area. These
factors have relegated attached growth
process design to empirical relationships
that are of limited usefulness.
ttile 2. Summary of Total Annual Costs for Plants Utilizing Attached Growth Treatment Processes
Annual Cost Summary, $11000 gal
Plant Size, mgd
Process
10
25
'ingle-Stage Nitrification
lastic Media
IBC's
3.28
2.65
2.07
1.62
1.80
1.40
1.44
1.12
50
100
Carbonaceous Oxidation
toc/t Media
lastic Media
IBC's
f/SC
3.86
2.93
2.53
3.09
2.59
1.74
1.48
1.69
2.32
1.41
1.22
1.38
1.88
1.20
0.99
1.02
1.67
0.97
0.82
0.85
1.60
0.94
0.77
0.79
1.18
0.94
1.17
0.94
-------
Empirical models based on statistical
curve fitting of data to variations in
operating conditions and physical
facilities are most commonly used by
design engineers. The actual
phenomenon involved in organics
removal may or may not be understood
from the resulting statistical model.
These empirical models yield varying
results that do not reflect the true
removal phenomenon. It is important to
realize this limitation and restrict the
application of the empirical models to the
range of operating conditions and
wastewater characteristics for which they
have been developed.
Techniques classified as rational
approaches better describe the removal
mechanisms, but they also present
difficulty in application. The Williamson
and McCarty biofilm model represents
the rational approach, although it is rather
complex and may be beyond general use
by design engineers. This model
considers many factors that describe
substrate utilization by biofilms. Basically,
it predicts soluble substrate removal
based on limitations of oxygen and
substrate diffusion through the liquid and
the biofilm into the bacteria. It also
considers the simultaneous effects of
biochemical reactions. The biofilm
surface area is a key design parameter.
Empirical Models
Empirical predictive design techniques
for trickling filters have been presented
by several investigators. The complete
project report for this study describes
several empirical models including the
National Research Council (NRC), Caller
and Gotaas, modified Velz, and the
rational model of Williamson and
McCarty.
A variation of the basic Velz equation is
presented in this summary report:
, BOD_ out,
In 5__ =K
L BOD, in J
69SQ/A
—
6960j
(1)
where: K = coefficient related to media
volume gpm"/(ft3)"
Q =flow rate to the filter
including recirculation, mgd
A = filter surface area, ft2
D = filter depth, ft
n = hydraulic coefficient
v = filter volume. 1,000 ft3
The variation in K with varying media
wetting rates (applied hydraulic loading to
plan surface area of trickling filter) is
predicted by the following equation for
rock media trickling filters:
K = 0.25 + (1nqw)/20
(2)
where: qw = media wetting rate, gpm/ft2
Model Evaluation
The designer is faced with selecting a
media volume for which the effluent
criteria may be attained with a reasonable
degree of confidence. In the following
discussion, data are presented for
existing attached growth systems. The
Velz model generally is used to predict
effluent soluble BOD5 from the trickling
filter. Sometimes it is used with influent
soluble BOD5. Since influent BOD5 is
hydrolyzed quickly, the author believes it
is inappropriate to use influent soluble
BOD5. The model has been applied in
this report to predict effluent total BOD5
after the final clarifier. The model might
be more precise if used to predict
effluent soluble BOD5 and if effluent
insoluble BOD5 were estimated, but the
precision of the model is not adequate to
justify such refinements.
Tables 3, 4, and 5 present field data
and predicted results for rock media,
fabricated media, and RBC systems,
respectively. Variables used in the
equations to predict performance are
given in Table 6.
It is noteworthy that the K values in
Equation 1 for rock media trickling filters
approach those of plastic media at higher
wetting rates:
Wetting Rate (qj,
gpm/ft2
K,
0.1
0.2
0.3
0.4
0.15
0.18
0.20
0.22
An "n" value of 0.5 has been used in
these comparisons. The performance of
plastic media trickling filters was
predicted using a K of 0.21 gpmos/ft15
for wetting rates varying from 0.5 to 2.27
gpm/ft2 The probable reason that the
specific surface area of plastic media is
not more effectively utilized at
conventional organic loading rates in
comparison to rock media is oxygen
diffusion limitations. The treatment
efficiency achieved with both typ
media will be determined b<
availability of oxygen and
effectiveness of the media to aera
wastewater.
Richards and Reinhardt invest
different configurations of plastic
using variable depths with the
media volume and found
performance improved with depth
media specific surface areas used i
investigation did not vary. Their fi
indicated that the 45° and 60° cro.1
configurations performed better
either the vertical configuration or r.'
dump media. When they evaluatec
plant data, they found an "n" of (
best mimic performance of soluble
removal. They used an "n" of
compare field data.
Rotating Media Biological
Contractor (RBC's)
The design approaches propos
RBC manufacturers are primarily
on "rational" models. One such ap
is summarized in the grai
relationship between effective
surface area (expressed as flow f
of surface area) and effluent :
BOD5 shown in Figure 1.
relationship indicates benefits fron
media with high specific surface
The design approach shown in F
is based on soluble BOD5 in the
and effluent. Unfortunately, the
soluble BOD5 portion is highly v
For example, the following havi
reported for soluble BO05 in |
effluents:
Plant
Soluble BO
Pewaukee, Wl
Seattle, WA
Tucson, AR
66
31-50(41 av
50-71 (56 av
The use of influent soluble
assumes that insoluble BOD5 is r
by some mechanism other than b
stabilization. Some insoluble c
may be incorporated in biologi
and removed by sedimentation, t
will be hydrolyzed and metal
Therefore, a design approach
based on only soluble organic lo
a liberal one. Since hydr
partjculate organics as well as
organics are available substr;
design (substrate removal ap
empirical approach, or other) st
based on total influent substrate.
-------
To provide a design approach more
insistent with stationary media attached
•owth processes and to enable realistic
valuation of the available data, Equation
has been applied to the RBC process.
vailable data for mechanically driven
sc and lattice-type RBC systems have
een evaluated using this approach and
ere summarized earlier in Table 4.
lese data represent both full-scale and
lot-plant installations.
Because lattice media have greater
jrface area per unit volume than disc
ledia, an analysis of the data was also
erformed relating BOD5 removal to
»edia surface area according to the
illowing equation:
BOD out
In - - - I = -K
(3)
BOD. in
5
The performance data in Table 4 have
een evaluated in terms of ks, the
(efficient related to media surface area,
pmn/(ft2)". Figure 2 represents a
robability distribution plot of the
alculated ks values that imply that media
pecific surface area is a more significant
arameter for the design of RBC process
erformance than media volume. Using a
s value of 0.062 gpm°5/ft and media
densities of 20 ft2/ft3 for the disc media
and 30 ft2/ft,3 for the lattice media, the
standard error of estimate would be 5
mg/L.
Trickling Filter/Solids Contact
The inability to accurately predict
trickling filter process performance and
the need for uniformly reliable effluent
quality have led to the development of a
variety of combined trickling filter-
suspended growth systems. The TF/SC
process is one of the coupled processes
consisting of a trickling filter followed by
an aeration basin. The trickling filter is
lightly loaded, usually 20 to 50 Ib
BOD5/1,000 ft3/day. The aeration basin
detention time may be 10 min to as long
as 1 hr.
The TF/SC process relies on the
trickling filter to stabilize the majority of
the organics while the aeration basin
completes the stabilization of the
organics and conglomerates the solids
into a settleable floe.
The evaluation of coupled processes is
complicated by the difficulty in separating
the removal occurring in the individual
process units. The data presented by
most investigators are not complete;
therefore, a thorough evaluation is not
possible. The design and evaluation
procedures used in this report are based
on the following:
• Assume the trickling filter performs in
the same manner that it would when
operating alone.
• The trickling filer soluble BOD will exert
a synthesis oxygen demand of 0.5 Ib
02/lb soluble BOD5 synthesized.
• The endogenous oxygen demand will
be 1.2 Ib 02/lb insoluble BOD5 or
synthesized cellular material.
An example of the application of these
concepts is presented in Table 7 for the
field data collected for the Corvallis, OR,
TF/SC plant. The Corvallis plant consists
of a trickling filter followed by a solids
contact aeration basin of 0.02 mil gal
volume. The final report describes
temperature consideration, nitrification
design equations, and example design
illustrations.
Conclusions
This report is a consolidated volume
describing the methodology involved in
designing attached growth biological
wastewater treatment processes to
achieve carbonaceous oxidation
able 3. Comparison of Predicated vs. Measured Effluent BOD5 Using Rock Media Trickling Filter Data
Plant Location
Aurora, IL
Dayton, OH
Oruham, NC
Madison, Wl
Richard, TX
"lainfield, NJ
Great Neck, NY
Oklahoma City, OK
-reemont, OH
Storm Lake, IA
lichland, WA
Misal, CA
Chapel Hill, NC
Dallas, TX
Bridgeport, Ml
Jass City, Ml
Charlotte, Ml
lillsdale, Ml
apeer, Ml
•tate Prison, Ml
assar, Ml
nglewood, CO
orvallis, OR
orvallis, OR
Depth, ft
6.0
7.5
7.0
10.0
6.5
6.0
4.0
6.0
3.3
8.0
4.5
32
4.25
7.5
6.0
6.0
6.0
6.0
5.8
8.0
5.6
4.4
8.0
8.0
R
—
—
—
—
-
06
1.0
1.0
1.5
2.1
2.8
3.1
2.0
0.5
1.2
1.3
—
—
0.3
0.1
1.7
1.0
2.4
05
0/A, mgd/ac
2.1
3.5
1.9
2.4
3.9
2.4
7.8
16.3
19.0
21.5
19.6
20.8
16.3
5.6
20.6
10.0
7.7
3.6
73.5
3.8
9.2
74.8
24.6
24.6
W/V, Ib
8005/7,000
fWday
4.4
12
13
6.4
73.3
25
20
78
41
62
44
53
19
21.4
29
23
29
10
22
13
6
60
16
19
BODj,
In
70
138
261
738
778
76
117
300
95
381
118
185
77
225
99
151
119
91
65
153
59
158
86
49
mg/L
Out
14
33
68
33
20
73
20
66
27
67
20
24
44
37
42
33
63
32
23
17
29
46
32
31
Predicted
Effluent BODj,
mg/L, from
Equation 1
20
34
66
27
32
15
32
78
32
63
25
49
79
45
26
30
39
26
27
34
77
49
32
18
-------
Table 4. Comparison of Predicted vs. Measured Effluent BOD5 Using Plastic Media Trickling Filter Data
Plant Location
Indianapolis, IN
Stockton, CA
Akron, OH
Buena Vista, Ml
Bay City, Ml
Essexville, Ml
Greenville, Ml
Rockwood, Ml
' Indio, CA
2 Linden Rochelle, NJ
3
3
Media
Plastic
Plastic
Plastic
dumped
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
Depth, ft
21.5
21.5
25.5
20.0
21.5
21.5
21.5
22.0
33.0
21.5
20.0
10.0
q, gpm/ft2
2.0
0.28
0.36
0.46
0.90
0.75
0.46
0.32
0.27
1.10
1.4
0.6
Rate, gpm/ft2
2.0
0.71
0.75
1.20
1.1
1.50
0.50
0.97
--
2.77
1.4
0.06
' Drury, D. D., Carmota, III, J., and Degadillo, A., "Evaluation of High Density Cross Flow Media for
58(5):364, May 1986.
2Fillos, J., Nierstedt, R., and Donahur, A, "Full Scale Evaluation of Plastic Media Roughing Filters,
New Orleans, LA, October 1984.
3 Richards, T. and Reinhart, D., "Evaluation of Plastic Media in Trickling Filters," JWPCF, 58(7):774
8C
In
112
240
120
54
79
23
62
61
62
100
78
76
JDs, mg/L
Out
57
40
20
21
18
11
15
23
72
50
29
41
Predict
Effluent B
mrj/L fn
Equatio,
56
38
18
14
28
7
15
10
46
40
36
42
Rehabilitating an Existing Trickling Filter, " J
" Presented at 57th Annual WPCF Con fere
, July 1986
Table 5. Comparison of Predicted vs. Measured Effluent BOD5 Attached Growth Model Using RBC Data*
Plant Location
Pewaukee, Wl
Pewaukee, Wl
Edgewater, NJ
Gladstone, Ml
Gladstone, Ml
Woodland, WA
Kirksville, MO
Georgetown, KY
Brainerd, MN
Media
Disc
Disc
Lattice
Disc
Lattice
Lattice
Lattice
Lattice
Lattice
Volume, ft3
197
10,450
6,110
196
16,300
2,413
63,100
25,240
40.715
0, gpm
8.3
235.0
333.0
10.4
550.0
104.0
904.0
765.0
950.0
SOOg,
In
172
119
133
100
106
175
164
150
80
mg/L
Out
33
20
38
32
20
28
15
21
17
Predict
Effluent £
mg/L fr
Equatio
38
15
35
26
20
40
12
25
20
'Lehman, P. J., 'Start-up and Operating Characteristics of an RBC Facility in a Cold Climate," JWPCF, 55(10):1233, October 1983.
Table 6. Variables Used for Models Evaluation
Modified Velz Parameters Rock Media
Plastic Media
RBC's
n
K (Equation 1)
0.5
(Equation 2)
0.5
0.21
0.5
0.308
(secondary treatment) and nitrification of
domestic wastewater. The theoretical
considerations given to design are
reviewed, and detailed examples using
the most accurate approaches are
presented. Cost analyses were facilitated
by using a computer; however, the
procedures are straightforward and can
easily be done manually.
Several mathematical models have
been used to design attached growth
systems. None are particularly accurate
in predicting process performai
some are quite complicatt
carbonaceous removal, the Velz
is as accurate as any and
conveniently applied to all
growth processes. The Velz equ
-------
30
25
20
Q
O
00
J> 15
to
0)
70-
5 -
/?flC Process Design Criteria
Domestic Wastewater Treatment
Wastewater Temperature = 5
4-Stage Operation
Influent Soluhif «OOS mg/L
ISO 120 100
1 1 1 1 1 1—
0 0.5 1.0 1.5 2.0 2.5 3.0
Hydraulic Loading, gpd. ft2
Igun 1. Manufacturer's design approach for RBC's.
3.5
—i—
4.0
—i—
4.S
a applied to rock media, plastic or
spropriate modifications.
Total plant capital and O&M costs have
»en estimated for various size facilities
sing attached growth biological
•ocesses for secondary treatment
arbonaceous oxidation) and for
nitrification in the final report. RBC's are
estimated to be the most economical
attached growth process for
carbonaceous oxidation and for single-
stage nitrification. The estimated costs for
the TF/SC process are essentially the
same as for the RCB process above 10
mgd. The relative ranking of these costs
for estimating purposes should be
tempered by site-specific conditions and
engineering judgment.
This report was submitted in fulfillment
of Contract No. 68-03-2556 by CWC/HDR
Engineers under the sponsorship of the
U.S. Environmental Protection Agency.
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0.088
0.080
0.072
0.064
0.056
0.048
0.040
5 10 20 30 40 50 60 70 80 90
Percent of Time Ka is Equal to or Less Than Stated Value
Figure 2. Probability of RBC performance based on media surface area
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'able 7. Evaluation of TF/SC Process
lorvallis TF/SC Plant (1983-1984)
Month
Q, mgd
Temp., °C
Influent
800$, mg/L
TSS, mg/L
TF Effluent
SODj, mg/L
SSOOg, mg/L
rSS, mg/L
Cn mg/L
Cg, mg/L
Or, mgd1
Solids
Aeration, Ib2
Reaeration, Ib3
Clarifier, Ib4
Total, Ib
SRT, days
BODs/TSS Ratio6
Oxygen Demand,
Ib/day
Synthesis7
Endogenous
Aeration^
Endogenous
Reaeration9
Oxygen Demand,
mg/Uhr
O2 Demand
Aeration10
O2 Demand
Reaeration"
Apr.
12.2
15
66
75
25
6
63
13,075
3,110
3.8
520
2,180
17,300
20,000
3.1
0.3
90
63
266
38
67
May
74
18
90
82
34
5
72
8,091
2,150
2.7
360
1,350
7,600
9,310
2.1
0.4
71
72
270
36
68
June
7.3
20
87
74
32
6
61
8,180
1,940
2.3
324
1,364
6,450
8,138
2.2
0.4
91
75
154
42
39
July
6.2
20
78
68
28
5
60
6,345
1,768
2.4
295
1,060
5,280
6.635
1.9
0.4
69
68
244
34
61
Aug.
6.2
22
72
63
29
5
57
5,437
1,557
2.5
260
907
4,700
5,867
1.8
0.4
74
69
240
36
60
Sept.
5.7
22
94
68
39
8
59
5,415
1.675
2.6
280
903
4,800
5,983
1.9
0.53
112
98
170
53
43
Oct,
5.6
21
114
66
38
8
56
70,293
2,948
2.2
490
1,720
8,040
10,250
3.3
0.54
108
164
572
68
143
Nov.
15.2
17
56
56
33
6
55
13,703
3,571
5.4
595
2,285
25,560
28,340
4.0
0.5
106
139
534
61
134
Dec.
17.9
14
35
58
26
4
59
76,739
4,278
6.3
703
2,690
35,520
38,973
4.5
0.36
63
707
368
43
92
Jan.
13.4
14
49
56
26
4
54
17,170
4,777
5.2
797
2,870
30,800
34,464
5.5
0.42
58
127
457
46
774
Feb.
16.6
13
56
64
22
3
59
76,523
4,832
6.9
806
2,760
39,390
42,956
4.8
0.32
44
91
312
34
78
Mar.
12.7
13
48
64
22
3
58
75,353
4,982
6.1
830
2,560
32,550
35,940
5.3
0.33
41
97
299
35
75
' Q, = <
2 Aeration Ib solids = CaxVax 8.34 = Cax 0.02 x 8.34
3 Reaeration Ib solids = CrVrx8.34 = Crx 0.02 x 5.34
4 Clarifier Ib solids = (0, * Q,) Ca x 8.34/24, assuming 1-hr time to achieve Cr
5 Total Ib solids/(Q in x TF TSS out x 8.34)
« BODs/TSS ratio = (TF 8O05 out - TF SBOD5 out)/TF TSS out
7 Synthesis Oxygen, 0.5 xTF SBOD5 out x 24 x Vax 8.34
KSK,
KSK, ta+1
» Endogenous Oxygen, Aeration, Ibid = 1.2 Cax 8.34 x (BODs/TSS ratio)
' Endogenous Oxygen, Reaeration, Ib/d = 1.2 Crx 8.34 x (BODJTSS ra
'° Oxygen Demand Aeration, mg/Uhr = (Synthesis + Endogenous Aeration)/(V, x 8.34 x 24)
'' Oxygen Demand Reaeration, mg/Uhr = (Endogenous Aeratin)/(Vr x 8.34 x 24)
Vhere: Q, = RAS flow mgd
0, = In flow mgd
Ca = MLSS, mg/L
Cr = RAS concentration, mg/L
V, = Aeration basin volume, mil gal
Vr = Reaeration basin volume, mil gal
TF SS out - trickling filter effluent suspended solids, mg/L
TT BOD out = trickling filter effluent 800$, mg/L
TF SBOD out = trickling filter effluent soluble 800$, mg/L
Ks= lShri@20'C
Ke = 0.02 hr> @ 20"C
Kt = 1.072 (T-20)
t = aeration detention time, hr
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Henry H. Benjes, Jr., is with CWC/HDR Engineers, Dallas, TX 75230.
John J. Convery is the EPA Project Officer (see below).
The complete report, entitled "Capital and O&M Cost Estimates for Attached
Growth Biological Wastewater Treatment Processes," (Order No. PB 89-148
3241 AS; Cost: $36.95, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
10
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