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

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    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

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                           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.

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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

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"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

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                               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

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                                             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

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 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.

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                                              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

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 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.

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      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

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                   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

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 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

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           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

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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

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      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

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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

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                                            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)

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                 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

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      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

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 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

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                                                       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)

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                    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

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 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

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     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

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                                         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)

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                        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

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 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

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                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
                                                                        
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                          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

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