ROBERT A. TAFT WATER RESEARCH CENTER
REPORT NO.TWRC-9
COST AND PERFORMANCE
ESTIMATES FOR TERTIARY
WASTEWATER TREATING PROCESSES
ADVANCED WASTE TREATMENT RESEARCH LABORATORY -IX
U.S. DEPARTMENT OF THE INTERIOR
FEDERAL WATER POLLUTION CONTROL ADMINISTRATION
OHIO BASIN REGION
Cincinnati, Ohio
-------
COST AND PERFORMANCE ESTIMATES FOR TERTIARY
WASTEWATER TREATING PROCESSES
by
Robert Smith
Walter F. McMichael
U. S. Department of the Interior
Federal Water Pollution Control Administration
Advanced Waste Treatment Research Laboratory
Robert A. Taft Water Research Center
Cincinnati, Ohio
June, 1969
-------
FOREWORD
In its assigned function as the Nation's principal
natural resource agency, the United States Department of
the Interior bears a special obligation to ensure that
our expendable resources are conserved, that renewable
resources are managed to produce optimum yields, and that
all resources contribute their full measure to the prog-
ress, prosperity, and security of America -- now and in
the future.
This series of reports has been established to pre-
sent the results of intramural and contract research
studies carried out under the guidance of the technical
staff of the FWPCA Robert A. Taft Water Research Center
for the purpose of developing new or improved wastewater
treatment methods. Included is work conducted under co-
operative and contractual agreements with Federal, state,
and local agencies, research institutions, and industrial
organizations. The reports are published essentially as
submitted by the investigators. The ideas and conclusions
presented are, therefore, those of the investigators and
not necessarily those of the FWPCA.
Reports in this series will be distributed as supplies
permit. Requests should be sent to the Office of Informa-
tion, Ohio Basin Region, Federal Water Pollution Control
Administration, 4676 Columbia Parkway, Cincinnati, Ohio
45226.
-------
COST AND PERFORMANCE ESTIMATES FOR TERTIARY WASTEWATER TREATING PROCESSES
Robert Smith and Walter F. McMichael
Treatment Optimization Research Program
This report contains generalized estimates of both performance
and cost for wastewater treatment processes which can be used down-
stream of the activated sludge process to reduce the pollution
load on the receiving stream. Cost and performance estimates given
are believed to be the most valid and up-to-date information now
available. No attempt has been made to treat every process, process
modification, or process group proposed for tertiary treatment.
Processes treated reflect only the current thinking in this
technological area. Processes and groups of processes believed to
be leading candidates for use downstream of secondary treatment are
shown in Figure 1. The group of processes selected for use by the
process designer will depend on the water quality requirements at
the receiving stream. For example, if only partial removal of organic
contaminants such as BOD, COD, or TOC is required, microscreening
or rapid filtration can be used to remove about 70% of the suspended
solids which represent a significant portion of the organic
contaminant.
Data from various sources on the fraction of 5-day BOD
associated with suspended solids are shown in Table 1. Similar
data for COD are given in Table 2. Obviously, this fraction is
strongly dependent on the operating mode of the aerator as well as
the efficiency of the final settler in preventing suspended solids
-------
"T
MS
LC
MMF
AS
GCA
RC
Microscreening
Lime Clarification
Multi-Media Filtration
Ammonia Stripping
Granular Carbon Adsorption
Recarbonation
WASTEWATER TREATMENT PROCESSES FOR USE DOWNSTREAM OF SECONDARY TREATMENT
FIGURE 1
-------
Table 1
MEASUREMENTS ON THE FORM OF ORGANIC
SPECIES IN ACTIVATED SLUDGE PROCESS EFFLUENT
F/T BQpP TBODg Delta BOD/Delta SS7
Hyperion (3 weeks)
1. 6 hr detention, 20OO mg/1 .57 4.4 .35
2. 6 hr detention, 3000 mg/1 .72 5.0 .18
3. 5 hr detention, 3500 mg/1 .61 8.0 .214
4. 4 hr detention, 3000 mg/1 .53 9.0 .27
5. 4 hr detention, 2000 mg/1 .25 12.2 .35
Washington, D. C. Blue Plains Plant (2 months)
2.5 hr detention, 444 mg/1 .39 45.0 .70
26th Ward Plant, New York (6 years)
2.4 hr detention, 260 mg/1 .44 36.O .61
Tallmans Island Plant (6 years)
4.0 hr detention, 773 mg/1 .44 19.O .40
Hunts Point Plant, New York (6 years)
2.8 hr aeration, 750 mg/1 .40 18.5 .55
Rockaway Plant, New York (6 years)
1.8 hr aeration, 480 mg/1 .43 33.0 .55
Jamaica Plant, New York (6 years)
1.6 hr aeration, 93O mg/1 .52 35.0 .41
a TBOD = Total 5-Day BOD (Dissolved + Particulate)
p F/T = Filtrate 5-Day BOD/TBOD
y (TBOD - Filtrate BOD)/Suspended Solids
-------
Table 2
FILTERED AND UNFILTERED CHEMICAL OXYGEN DEMAND MEASUREMENTS
ON
ACTIVATED SLUDGE EFFLUENT
Hyperion Treatment Plant
Los Angeles, California
1. 6 hr. detention, 20OO
2. 6 hr. detention, 30OO
3. 5 hr. detention, 350O
4. 4 hr. detention, 30OO
5. 4 hr. detention, 200O
6. 4 hr. detention, 1OOO
7. 6 hr. detention, 100O
Pomona Treatment Plant
Pomona, California
1. Mean Cell Residence Time
2. Mean Cell Residence Time
3. Mean Cell Residence Time
4. Mean Cell Residence Time
mg/1 MLSS
mg/1 MLSS
mg/1 MLSS
mg/1 MLSS
mg/1 MLSS
mg/1 MLSS
mg/1 MLSS
me = 4.9 days
me = 4.8 days
me = 9.4 days
me = 9.3 days
VSS
mg/1
4.4
6.O
12.5
11.6
22.8
16.6
13.0
SS
mg/1
8.0
20.0
11.0
7.6
TCOD
mg/1
29.8
33.8
40.0
42.0
82.4
91.4
56.6
TCOD
mg/1
53.0
82.0
49.0
39.0
DCOD
mg/1
26.1
27.4
28.4
30.4
41.5
49.5
43.3
DCOD
mg/1
44.0
54.0
36.0
27.0
SCOD/TCOD
.12
.19
.29
.28
.50
.46
.24
SCOD/TCOD
.17
.34
.27
.31
ACOD/VS
.84
1.1
.93
1.0
1.8
2.5
1.0
ACOD/SS
1.1
1.4
1.2
1.6
VSS = Volatile Suspended Solids
SS = Suspended Solids
TCOD = Unfiltered COD
ACOD = Filtered COD
ACOD = TCOD - DCOD
-------
from escaping in the effluent stream. For a reasonably well designed
and operated activated sludge plant, the concentration of various
contaminants that might be expected in the effluent stream are
shown in Table 3.
Based on the values shown in Tables 1 and 2, it has been
assumed that 60% of the 5-day BOD is in the form of particulate.
COD and TOC were assumed to be 70% dissolved and 30% particulate.
Microscreening or rapid sand filtration can, therefore, be expected
to remove about 42% of the 5-day BOD and 21% of the ODD and TOC.
Other solids removing processes, such as lime clarification, multi-
media filtration, and granular carbon adsorption, will remove a
greater fraction of the suspended solids. Some small fraction of
the dissolved organic contaminants might be removed, but for a first
approximation this appears to be negligible. A large fraction of
the dissolved organic species is removed by granular carbon
adsorption.
Estimates of the concentrations of BOD, ODD, TOC, nitrogen, and
phosphorus downstream of each group of processes are shown in Table
3- • Estimated capital and operating and maintenance costs for each
process are shown in Figures 2 through 7. The cost for any group of
processes can be found by adding the cost for the individual processes
in the group.
-------
Table 3
ESTIMATED WATER CONTAMINANT CONCENTRATIONS .IN
EFFLUENT STREAM FROM VARIOUS GROUPS OF TERTIARY PROCESSES
O. Secondary Effluent
1. Microscreening or
Rapid Sand Filtration
(la, 2, 7a)
2. Granular Carbon Adsorption
(Ic, 4, 5, 7c)
3. Lime Clarification
(Ib, 2, 3, 3a, 4, 7b)
4. Lime Clarification +
Multi-Media Filtration
(Ib, 2, 3, 3a, 6, 5, 7c)
5. Lime Clarification +
Ammonia Stripping
(Ib, 2, 3, 4, 7b)
6. Lime Clarification +
Ammonia Stripping +
Granular Carbon Adsorption
(Ib, 2, 3, 4, 5, 7c)
* 3d,
C M
Q) O W
o a *
H H MHO)
w \ Q\ Q\ y\ +• \ o\
(ODt QOtOO^OOt -rl Ol 42 O*
>effleoeHB zscLS
Remarks
20 13 60 20 17 10
6 7.5 47 16 17 10 70% Removal of Suspended Solids
2 2 10 3 17 10 90% Removal of Suspended Solids
2 6 44 15 17 1 90% Removal of Suspended Solids
<1 5 42 14 17 1 99% Removal of Suspended Solids
2 6 44 15 2 1 90% Removal of Suspended Solids
<1 1 9 3 2 1 99% Removal of Suspended Solids
^•Dissolved
-------
FILTRATION AND MICROSCREENING
As a tertiary process, filtration has application first a* a
roughing filter which is competitive with the microscreening process
and as a polishing filter which would normally be used downstream
of the lime clarification process.
The roughing filter has been investigated by Truesdale and
Birkbeck in England and by the Metropolitan Sanitary District of
2
Greater Chicago . The roughing filter used by Truesdale and Birkbeck
removed about 6O% of the suspended solids from a secondary effluent
containing 17 mg/1 of suspended solids. Microscreening equipment
investigated by Truesdale and Birkbeck in the same study removed 6O%
of the suspended solids also. The backwash water used was about 5%
of the throughput for both the filter and the microscreen. Backwash
water is returned to the secondary process.
2
Lynam, Ettelt, and McAloon at the Metropolitan Sanitary District
of Greater Chicago made measurements on a microscreening unit and a
roughing sand filter. The suspended solids in the secondary effluent
averaged about 11 mg/1. The average removal for the microscreen process
was 70% as compared to 75% for the sand filter. It was found at Chicago
that the principal filtering effect was obtained by the cake of suspended
solids held on the microscreen. The speed of the drum must, therefore,
be reduced as the suspended solid concentration in the influent stream
is reduced. Capital cost estimates for both microstrainers and filters
were made by the Chicago engineers and were found to be roughly
equivalent.
-------
The cost estimates shown in Figure 2 for microscreening were
derived from a mathematical model developed at the Federal Water
Pollution Control Administration's (FWPCA Taft Water Research
Center (TWRC)) at Cincinnati based on the work of Boucher3.
Microscreening of secondary effluent was also investigated by
the Department of Water and Power of Los Angeles at the Hyperion
Treatment Plant. With an average suspended solids concentration
in the secondary effluent of 21 mg/1, it was observed that about
65% of the suspended solids was removed by the microscreen.
In tests on a microscreening unit at Lebanon, Bodien and Stenburg
reported suspended solids removals of 89% with a fine mesh screen and
73% with a coarser screen. Influent suspended solids averaged 17
mg/1 with the fine screen and 27 mg/1 with the coarser screen. BOD
reduction averaged 61% for the coarse screen and 81% for the fine
screen.
To summarize, the microscreening and roughing filters are about
equal in both performance and cost.
Multimedia polishing filters which will remove essentially all
of the suspended solids from water can also be used downstream of
activated sludge or lime clarification. These filters can be used
with or without the addition of chemicals such as alum or poly-
electrolytes. Examples of this type of filter are the Microfloc
process* used at South Tahoe Public Utility District, the Zurn
#Mention of products and manufacturers is for identification only and
does not imply endorsement by the Federal Water Pollution Control
Administration and the U. S. Department of the Interior.
8
-------
MICROSCREENING OF SECONDARY EFFLUENT
Capital Cost, Operating & Maintenance Cost, Debt Service
vs.
Design Capacity
10.0
in
C
o
&
m
•p
c
o>
o
•p
c
•p
id
4 Cost Adjusted to March, 1969
- 111innii4uiu ui-uigmtiiimjjini-mt
O.10
0.01
4 5 6 7 8 9 10
0.01
1.0
10.0 1OO.
Design Capacity, millions of gallons per day
C = Capital Cost, millions of dollars
A = Debt Service, cents per 1000 gallons (4%% - 25 yr.)
0 & M = Operating and Maintenance Cost, cents per 1000 gallons
T = Total Treatment Cost, cents per 10OO gallons
Figure 2
-------
filter which was tested at the TWRC pilot plant in Lebanon, Ohio,
and the multimedia filters used both at Lebanon and the TWRC pilot
plant at the Blue Plains Plant in Washington, D. C. No chemicals
are added when the filter is used downstream of the lime clarifica-
tion process. The purpose of the filter in this application is to
remove inorganic fines which can cause considerable turbidity which,
in turn, would be undesirable for any reuse applications. At Tahoe
about 20O mg/1 of alum was added upstream of the filter. Tests made
on the Zurn multimedia pressure filter at Lebanon demonstrated good
performance with the addition of 12.5 mg/1 of alum and 2.5 mg/1 of
C-7 polyelectrolyte.
To summarize, the multimedia polishing filter is necessary for
the removal of turbidity when high quality water is required. In
treating water for discharge to a natural stream, the use of this
filter is probably not justified. Cost estimates (from reference 5)
for the multimedia filter without addition of chemicals are shown
in Figure 3. Operating and maintenance costs has been reduced by 1/3
to account for the fact that settling basins are not used.
LIME CLARIFICATION
The lime clarification process is used primarily for removal of
phosphorus and suspended organic matter. An additional benefit is
the increased pH resulting from lime addition which makes ammonia
nitrogen available for removal by air stripping. The type of
equipment used is an upflow clarifier with recirculation of lime
sludge. For hard water applications, one upflow clarifier appears
10
-------
FILTRATION THROUGH SAND OR GRADED MEDIA - 4GPM/SQ FT
Capital Cost, Operating & Maintenance Cost, Debt Service
vs.
Design Capacity
a
0
(8
01
(fl
-p
C
OJ
o
•p
c
8
(1)
10.
Cost Adjusted to March, 1969
4i.O
0.1
1.0
0.1
.01
-8
Vl
o
c
0
•H
•H
e
5
c
A
O & M
T
Design Capacity, millions of gallons per day
Capital Cost, millions of dollars
Debt Service, cents per 1OOO gallons (4%% - 25 yr.)
Operating and Maintenance Cost, cents per 1000 gallons
Total Treatment Cost, cents per 1000 gallons
11
Figure 3
-------
to be sufficient. For soft water, the most promosing arrangement
appears to be two upflow clarifiers in series with the ammonia
stripping tower downstream of the first clarifier, followed by a
recarbonation unit. It is expected that the carbon dioxide required
for recarbonation can be salvaged from the recalcination of the
waste lime sludge.
Lime requirements to reach any target pH can be reliably
calculated if the ionic character of the wastewater is known. In
general, waters with high hardness require less lime and operate
with lower pH values. Also some coagulant salt, such as ferrous
sulfate, may be needed to help settle the inorganic fines which would
otherwise escape in the effluent stream.
A 75 gpm unit has been operating at the Lebanon pilot plant for
more than one year. Calcium and magnesium concentrations in the
feed stream averaged 105 mg/1 and 29 mg/1 respectively. The TOC
of the feed stream averaged 28 mg/1. The concentration of phosphate
entering the process averaged 3O mg/1. Phosphate in the effluent
averaged about 2.2 mg/1. The removal of BOD averaged 86%, while the
removal of TOC and COD averaged 58%. An additional 5% of TOC was
removed by the dual media (anthrafilt and sand) downstream of the
clarifier. Good results were obtained by raising the pH to about
9.0 by the addition of about 25O mg/1 of hydrated lime.
12
-------
A second lime clarification pilot unit has been operated at
the TWRC Blue Plains pilot plant at Washington, D. C. The feed
stream there contains 40-50 mg/1 of calcium and 7-10 mg/1 of
magnesium, which is characteristic of soft water. The organic
content of the feed stream is also high, since the activated
sludge process upstream is of the modified type. The BOD
averages about 45 mg/1. Two upflow clarifiers in series with
recarbonation have been found likely to give the best results.
Ferrous sulfate can be used as a coagulant aid in the second
clarifier. This arrangement reduces the BOD level to about 15
mg/1. Similarly, a 50-60% reduction in TOC has been achieved,
resulting in a level of 14-15 mg/1 in the effluent stream. The
lime requirement to raise the pH to 11.5-12 is 350 mg/1 as CaO.
A dual media filter downstream of the twin clarifier unit reduces
the TOC by an additional 2 mg/1. Phosphate concentrations are
reduced by 93%, giving an effluent concentration of about 1.5 mg/1.
The installed cost of equipment was taken from cost estimates
for Infilco Densators supplied by Infilco/General American
Transportation Corporation, Tucson, Arizona. The Densators were
sized for an overflow rate of 100O gpd/sq. ft. at the mean flow
rate. At least one extra Densator was provided for shut-down to
provide for cleaning and repair. For example, at 1 mgd mean flow,
two 4O ft. dia. Densators were sufficient, but the cost is based on
three. For the 1O mgd plant size (mean flow), two 120 ft. dia.
Densators were sufficient, but three were provided. At the 100 mgd
13
-------
size, twelve 145 ft. dia. Densators were required, but 15 were
provided. The cost of lime feeding equipment was then added to
obtain the total equipment cost. It was visualized that the ammonia
stripping tower would be built over the second clarifier and that
recarbonation for pH adjustment would be accomplished in the second
clarifier. The cost of recarbonation equipment was considered minor
and was not included in the equipment cost. Twenty percent of the
equipment cost was added to provide for engineering and contingencies
giving the total capital cost shown in Table 4 and Figure 4.
Debt service was computed as 6.744% of the total capital cost
per year corresponding to interest at 4^% over a 25-year period. For
operating labor, it was estimated that 12 man-hr/day/mgd would be
sufficient at the 1 mgd size and that O.2 man-hr/day/mgd would be
adequate at the 4OO mgd size. The estimate for operating labor at
the 4OO mgd size was supplied by Infilco. These two points were
used to find the following relationship for operating labor.
Operating Labor, man-hr/day/mgd = 12(mgd)""
For maintenance labor, 3 man-hr/day/mgd was believed to be sufficient.
Electrical power requirements were obtained from Infilco and converted
to cost by taking the cost of power as 1 cent/kw-hr.
There is some evidence that a coagulant aid such as iron might be
required in the second clarifier. Since the need for this chemical
is not clearly established, it was not included in the cost. 5 mg/1
or iron, however, can be provided for about 0.44 cents/1000 gallons.
14
-------
Table 4
COST OF THE TWO CLARIFIER LIME CLARIFICATION PROCESS FOR SECONDARY EFFLUENT
TOTAL CAPITAL COST, dollars
PROCESS COSTS, cents/1000 gallons
1. Amortization, 4%% and 25 yr.
2. Operating Labor
3 . Maintenance Labor
#
4. Supervision and Payroll Overhead
**
5. Maintenance Materials
6. Electrical Power
TOTAL COST WITHOUT CHEMICALS
LIME RECALCINATION AND MAKE UP
TOTAL TREATMENT COST WITH RECALCINATION
1. Cost of Lime Delivered, 350 mg/1
2. Cost of Sludge Disposal
(hauling to land fill, 25 mile
one-way trip)
TOTAL TREATMENT COST WITH DISPOSAL OF
LIME SLUDGE TO LAND FILL
1 mgd
138,900
2.57
4.57
.942
1.65
.314
.05
10.10
9.17
19.27
2.70
.67
13.47
1O mgd
721 , 200
1.33
.952
.942
.558
.314
.05
4.15
3.67
7.82
2.70
.67
7.52
1OO mgd
4,922,000
.909
.198
.942
.339
.314
.05
2.75
1.92
4.67
2.70
.67
6.12
309 mgd
12,20O,OOO
.730
.092
.942
.310
.314
.05
2.43
1.4O
3.83
2.70
.67
5.80
* Taken as 30% of operating and maintenance labor
** Taken as 1/3 of maintenance labor (maintenance cost = 75% labor + 25% materials)
-------
TWO CLARIFIER LIME CLARIFICATION PROCESS
WITHOUT CHEMICALS
Capital Cost, Operating & Maintenance Cost, Debt Service
vs.
Design Capacity
20.0
a
0
8
O
c
0)
0
U)
8
rt
s
H
Cost Adjusted to March, 1969
ta 20.0
10.0
1.0
tn
M
rt
0
-o
01
0
•H
8
•H
s
0.10
1.0
Design Capacity, millions of gallons per day
C = Capital Cost, millions of dollars
A = Debt Service, cents per 1000 gallons (4% - 25 yr.)
O & M = Operating and Maintenance Cost, cents per 1000 gallons
T = Total Treatment Cost, cents per 1OOO gallons
16
Figure 4
-------
The total installed cost of lime recalcination facilities including
thickener, centrifuge, and furnace or kiln was obtained from the follow-
ing existing and planned plants:
Lake Tahoe $551,571 7.5 mgd
Piscataway, Md. $495,600 5.0 mgd
Dayton, Ohio $2,50O,OOO 125 mgd
Lansing, Mich. $1,5OO,OOO 62.5 mgd
Plotting these values for total capital cost, the following relationship
is found:
Total Capital Cost, dollars = $2OO,OOO (mgd)"50
The data from water treating plants such as Dayton, Ohio, Miami, Florida,
and Lansing, Michigan were converted to equivalent wastewater treating
installations by assuming that the ratio of lime produced in tons/day to1
mean flow in mgd was (1.2). This ratio was derived from experience at
Lake Tahoe where 9 tons/day of recalcined lime is produced in a 7.5
mgd wastewater treating plant. Actual data on operating manpower
obtained from Dayton, Lansing, Mich, and Miami, Florida were fitted
with the following relationship:
Operating Labor, man-hr/day/mgd = 7.8 (mgd)~*
The maintenance labor reported was found to average about O,6 man-hr/
day/mgd. Electrical power was found to be roughly proportional to
size. The cost of fuel, however, showed a marked reduction with size,
which might be attributed to the savings in heat loss or the reduced
price of fuel at the larger size plants. Make up lime was computed
using the assumption that 35O mg/1 of lime (CaO) is required and that
17
-------
1.2 tons/day/mgd is recovered through recalcination. The cost of
purchasing lime was taken as $18.50 per ton. Cost estimates shown
in Table 5 and Figure 5 represent the complete cost of supplying lime
to the lime clarification process. Total cost for the lime clarifica-
tion process can be found by adding the values shown in Figures 3 and
4 as demonstrated in Table 4.
AMMONIA STRIPPING
If an ammonia stripping tower is used with the lime clarification
process, the ammonia nitrogen can be removed at moderate cost. Even
though many problems associated with the use of this process remain
to be solved, it is presently viewed as the most promising process
for removing ammonia nitrogen from wastewater. For example, the
performance is strongly dependent on air and water temperature so
that use of the process may not be feasible during the winter months
when the temperature of ambient air is below 32°F. The probable
destruction of lignin in the wooden packing of the ammonia stripping
tower as a result of prolonged contact with high pH water possibly
may be corrected by substituting plastic or plastic-covered wood for
the normally used wooden packing. During the summer months, when
nitrogen removal is usually most important, the efficiency of ammonia
stripping should average about 90% removal of ammonia nitrogen.
A pilot ammonia stripping tower has been operated at Lake Tahoe
under summer conditions with greater than 90% removal of ammonia
nitrogen. A larger ammonia stripping tower has been recently
installed (3.5 mgd) at Lake Tahoe but performance much below 90%
18
-------
Table 5
RECALCINATION OF LIME SLUDGE FROM LIME CLARIFICATION PROCESS
VO
TOTAL CAPITAL COST, dollars
PROCESS COST, cents/1000 gallons
1. Amortization, 4%% and 25 yr.
2. Operating Labor
3. Maintenance Labor
4. Supervision and Payroll Overhead*
5. Maintenance Materials**
6. Electrical Power
7. Fuel
8. Make Up Lime, $18.50/ton
TOTAL RECALCINATION COST, cents/1000 gallons
RECALCULATION PLANT CAPACITY, tons/day
RECALCINATION COST, dollars/ton
1 mgd
200 , OOO
3.70
2.5
.190
.806
.063
.100
1.33
.48
9.17
1.2
72.4
10 mgd
640,000
1.18
.595
.190
.236
.063
.100
.824
.48
3.67
12.0
26.5
100 mgd
2,000,000
.37
.138
.190
.110
.063
.100
.47
.48
1.92
120.0
12.0
309 mgd
3,550,000
.066
.066
.190
.077
.063
.100
.353
.48
1.40
371.
7.6
* Taken as 30% of operating and maintenance labor
** Taken as 1/3 of maintenance labor (maintenance cost = 75% labor + 25% materials)
-------
LIME RECALCINATION PLUS MAKE UP LIME
FOR USE WITH LIME CLARIFICATION
Capital Cost, Operating & Maintenance Cost, Debt Service
vs.
Design Capacity
m
o
\~s
8
H
ifl
•P
C
0)
0
•p
m
8
id
0)
M
H
Cost Adjusted to March, 1969,
20.0
10.0
1.0
0.10
10
Design Capacity, millions of gallons per day
C = Capital Cost, millions of dollars
A = Debt Service, cents per 1000 gallons (4% - 25 yr.)
O & M = Operating and Maintenance Cost, cents per 1OOO gallons
T = Total Treatment Cost, cents per 1000 gallons
ui
M
rd
0
•0
VI
0
en
q
o
•H
H
iH
•H
B
8
•H
I
Figure 5
20
-------
removal has been experienced under winter operating conditions.
Pilot ammonia stripping towers are also being installed at the
Hanover Plant by The Metropolitan Sanitary District of Greater
Chicago but no tests results are, as yet, available.
A computerized design procedure for estimating performance and
cost of ammonia stripping towers has been completed by the Illinois
Institute of Technology Research Institute under contract to FWPCA.
Only one value for installed cost was found for ammonia stripping
towers. At Lake Tahoe, the installed cost of the tower was $224,500
and the cost of the concrete basin was $100,500 giving a total cost
of $325,000 for an installation sized at 3.75 mgd. Since it was
learned in talks with the Marley Co. that little economy of size is
realized for cooling towers, a capital cost line through this point
was drawn with a slope of (O.90). Bechtel Corp. estimated the cost
of a 30 mgd ammonia stripping installation as $2,575,000. This point
fell only slightly above the line with a 9/10 slope. Amortization
was taken as 4^% over a 25 year period, but this is assuming that the
film packing will not have to be replaced within the assumed period.
In talks with engineers at Lake Tahoe the opinion was expressed
that the packing might have to be replaced in ten years. Marley
Co. estimated that if the packing is replaced, the cost will be
between 50% and 60% of the installed cost. Marley Co., however,
feels that if additional large ammonia stripping towers are built,
the life can be extended by using improved materials for packing.
Since this problem is totally unresolved, no attempt was made to
account for the additional cost.
21
-------
Operating labor was estimated by assuming that 8 man-hr/day would
be sufficient at the 1 mgd size and that 40 man-hr/day would suffice
at the 1OO mgd size. A line through these two points is represented
by the following relationship':
Operating Labor, man-hr/day/mgd = 8.0 (mgd)""
Maintenance labor was estimated at 1.5 man/hr/day/mgd. Electrical
power was found by scaling up the Lake Tahoe plant which has a 100
horsepower fan and a 3O horsepower water pump. Cost of power was
taken as one cent/kw-hr. All costs associated with the process are
shown in Table 6 and Figure 6.
GRANULAR ACTIVATED CARBON
Most of the practical operating experience with the granular
carbon adsorption process for treating secondary effluent has been
gained at the Pomona, California pilot plant operated jointly by
FWPCA and the County Sanitation Districts of Los Angeles County.
This pilot plant, which has a design flow of 288,000 gpd, consists of
five downflow pressure contactors, four of which are normally in
operation. The contact time is 36-40 minutes. No pretreatment of
secondary effluent from the activated sludge plant is used. Secondary
effluent, however, is of high quality; 10 mg/1 suspended solids, 47
mg/1 COD, and 13 mg/1 TOC. Backwash water (8OOO gallons) is used
once a day to bachwash the first contactor. This represents about
22
-------
Table 6
COST ESTIMATES FOR AMMONIA STRIPPING OF LIME CLARIFIED WASTEWATER
TOTAL CAPITAL COST, dollars
PROCESS COSTS, cents/1000 gallons
1 mgd
95,000
10 mgd
100 mgd
309 mgd
760,000 6,000,000 17,000,000
1. Amortization, 4^% and 25 yr.
2. Operating Labor
3 . Maintenance Labor
4. Supervision and Payroll Overhead*
U, M
5. Maintenance Materials
6. Electrical Power
TOTAL TREATMENT COST, cents/1000 gallons
Note: Wages for Water, Steam, and Sanitary
1.76
2.51
.471
.894
.205
.69
6.53
1.40
.55
.471
.306
.205
.69
3.62
Systems Nonsupervisory Workers
1.11
.126
.471
.179
.205
.69
2.78
for March,
1.02
.060
.471
.159
.205
.69
2.61
1969 = <
* Taken as 30% of operating and maintenance labor
** Taken as 1/3 of maintenance labor (maintenance cost = 75% labor + 25% materials)
-------
AMMONIA STRIPPING PROCESS
Capital Cost, Operating & Maintenance Cost, Debt Service
vs.
Design Capacity
10
10.0
in
*J
s
o
8
2
H
Cost Adjusted to March, 1969
0.10
0.10
0.01
ID
M
-------
3% of the throughput. The wash water is returned to the secondary
plant. It is estimated that if 20 rag/1 of suspended solids are
applied, the backwash will be required twice a day using about 6%
of the throughput. The suspended solids concentration in the
effluent stream is normally less than 1 mg/1. About 8O95 of the
organic species (COD, TOC) are normally removed.
A recent preliminary design study by the M. W. Kellogg Company
under contract to FWPCA estimated that a design based on 5O minutes
contact time, would reduce a COD of 6O mg/1 in the feed stream to
7 mg/1 in the effluent stream. Estimated removal values shown in
Table 3 are based partially on this study. Cost estimates shown in
Figure 7 are also based on calculations of the Kellogg Company which
provides downflow, pressure contactors with 50 minutes contact time.
25
-------
GRANULAR CARBON ADSORPTION PROCESS
Capital Cost, Operating & Maintenance Cost, Debt Service
vs.
Design Capacity
c
o
rH
rH
01
o
o
o
rH
cn
C
0
#4
p
: 5 6 7 8 9 10
i.o 10.0 100.
Design Capacity, millions of gallons per day
C = Capital Cost, millions of dollars
A = Debt Service, cents per 1OOO gallons (4%% - 25 yr.)
0 & M = Operating and Maintenance Cost, cents per 1OOO gallons
T = Total Treatment Cost, cents per 100O gallons
26
0.10
en
-8
C
0
•H
-------
REFERENCES
1. Truesdale, G. A. and Birkbeck, A. E., "Tertiary Treatment of
Activated Sludge Effluent", International Filtration Conference
Water Pollution Research Laboratory, Stevenage, Herts (1967).
2. Lynam, B., Ettelt, G. and McAloon, T., "Tertiary Treatment at
Metro Chicago by Means of Rapid Sand Filtration and Micro-
Strainers" Presented at WPCF 41st Annual Conference, September,
-L9o8.
3. Boucher, P. L., "A New Measure of the Filterability of Fluids
with Application to Water Engineering", ICE Journal 24 DD
415-446, (1947). ' HF*
4. Bodien, D. G. and Stenburg, R. L., "Microscreening Effectively
Polishes Activated Sludge Plant Effluent", Water and Wastes
Engineering, Vol. 3, Nd. 9, September, 1966.
5. Smith, Robert, "Cost of Conventional and Advanced Treatment of
Wastewaters", Jour. WPCF (Annual Conference Issue) Vol. 40 No
9, pp. 1546-1574, September, 1968.
27
------- |