PB85-165744
Emerging Technology Assessment of
Phostrip a/0, and Bardenpho Processes for
Biological Phosphorus Removal
Weston (Roy P.), Inc., West Chester, PA
Prepared for
Environmental Protection Agency, Cincinnati, OH
Feb 85
Department of Commerce
Technical Information Service
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EPA/600/2-85/008
February 1985
EMERGING TECHNOLOGY ASSESSMENT OF
PHOSTRIP, A/0, AND BARDENPHO PROCESSES
FOR BIOLOGICAL PHOSPHORUS REMOVAL
Weston, Inc.
Designers-Consultants
West Chester, Pennsylvania 19380
EPA Contract No. 68-03-3055
Project Officer
E. F. Barth
Wastewater Research Division
Water Engineering Research Laboratory
Cincinnati, Ohio 45268
WATER ENGINEERING RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
£?S?SIAL PROTECTION AGENCY
CINCINNATI, OHIO 45268
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TECHNICAL REPORT DATA
(f lease read Instructions on the reverse before completing)
1. REPORT NO.
EPA/600/2-85/008
3. RECIPIENT'S ACCESSION NO,
Ife&ZM/ML
4. TITLR AND SUBTITLE
EMERGING TECHNOLOGY ASSESSMENT OF PHOSTRIP, A/0, AND
BARDENPHO PROCESSES FOR BIOLOGICAL PHOSPHORUS REMOVAL
5. REPORT DATE
February 1985
6, PERFORMING ORGANIZATION CODE
7. AUTHOR(S(
Weston, Inc.
8. PERFORMING ORGANIZATION REPORT NO.
9. PERFORMING ORGANIZATION NAME AND ADDRESS
Weston, Inc.
Weston Way
West Chester, PA 19380
10. PROGRAM ELEMENT NO.
CAZBTB
II. CONTRACT/GRANT NO.
Contract No. 68-03-3055
12. SPONSORING AGENCY NAME AND ADDRESS
Water Engineering Research Laboratory--Cin.,OH
Office of Rese&rch and Development
U.S. Environmental Protection Agency
Cincinnati, OH 45268
13. TYPE OF REPORT AND PERIOD COVERED
Final-Jimo lOR^-Sont 19Q4
14. SPONSORING AGENCY CODE
EPA/600/14
IS. SUPPLEMENTARY NOTES
Project Officer; E. F. Barth Telephone - (513) 684-7641
, Present Contact: James F. Kreissl (513 S 684-7611
16, ABSTRACT
An engineering evaluation of three proprietary processes for biological removal of
phosphorus from municipal wastewater was conducted. The report presents for each
process: Technology Description;
Technology Evaluation;
Development Status;
Equivalent Technologies Comparison;
Assessment of National Impact;
Cost Considerations; and
Recommendations.
17.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDEP TERMS
c. COSATI Field/Group
Phosphorus removal
Anoxic
Anaerobic
Aerobi c
Cost
Biological processes
Activated sludge
Nutrient control
13B
18. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS {ThisReportl
UNCLASSIFIED
21. NO. OF PAGES
116
20. SECURITY CLASS fTlris page!
UNCLASSIFIED
22. PRICE
BB4 e..n
IS OBSOLETE
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DISCLAIMER
"The information In this document has been funded wholly or in part
by the United States Environmental Protection Agency under Contract No.
68-03-3055 to Weston, Inc. It has been subject to the Agency's peer and
administrative review, and it has been approved for publication as an EPA
document. Mention of trade names or commercial products does not constitute
endorsement or recommendation for use."
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FOREWORD
The U.S. Environmental Protection Agency is charged by Congress with
protecting the Nation's land, air, and water* systems. Under a mandate of
national environmental laws, the agency strives to formulate and implement
actions leading to a compatible balance between human activities and the
ability of natural systems to support and nurture life. The Clean Water
Act, the Safe Drinking Water Act, and the Toxics Substances Control Act
are three of the major congressional laws that provide the framework for
restoring and maintaining the integrity of our Nation's water, for pre-
serving and enhancing the water we drink, and for protecting the environ-
ment from toxic substances. These laws direct the EPA to perform research
to define our environmental problems, measure the impacts, and search for
solutions.
The Water Engineering Research Laboratory is that component of EPA's
Research and Development program concerned with preventing, treating, and
managing municipal and industrial wastewater discharges; establishing
practices to control and remove contaminants from drinking water and to
prevent its deterioration during storage and distribution; and assessing
the nature and controllability of releases of toxic substances to the air,
water, and land from manufacturing processes and subsequent product uses.
This publication is one of the products of that research and provides a
vital communication link between the researcher and the user community.
The innovative and alternative technology provisions of the Clean
Water Act of 1977 (PL 95-217} provide financial incentives to communities
which use wastewater treatment alternatives that reduce costs or energy
consumption over conventional systems. Some of these technologies have
been only recently developed and are not in widespread use in this country.
In an effort to increase awareness of the potential benefits of such alter-
natives and to encourage their implementation where applicable, the Water
Engineering Research Laboratory has initiated this series of Emerging Tech-
nology Assessment reports. This document discusses the applicability and
economic feasibility of utilizing biological processes for the control of
phosphorus for municipal wastewater treatment.
Francis T. Mayo, Director
Mater Engineering Research Laboratory
m
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ABSTRACT
This technology assessment addresses three proprietary proc-
esses (namely PhoStripf &/o, and Bardenpho) for biological phos-
phorus removal from municipal wastewaters. These processes are
used as alternatives to the conventional method of treatment by
activated sludge with chemical addition for phosphorus precipi-
tation, The objective of this report is primarily to provide
guidance to those individuals involved with reviewing new proc-
esses as part of the Innovative and Alternative Technology pro-
gram.
PhoStrip, &/Q, and Bardenpho processes were all developed
in the early 1970"s based on the ability of the biological sys-
tem to provi.?^ enhanced or the so called "luxury" uptake, which
involves the mechanism of phosphorus release by microorganisms
under anaerobic conditions, followed by cellular phosphorus up-
take under aerobic conditions. These three systems are different
with respect to their specific process design and to their abil-
ity to provide phosphorus removal, as well as various degrees of
nitrogen removal. The PhoStrip process employs sidestream (i.e.,
a portion of the return sludge) treatment in an anaerobic con-
tact tank where biologically-bound phosphorus is released to the
aqueous medium, and the supernatant liquor is treated with lime
to precipitate inorganic phosphorus as calcium hydroxyapatite.
Both the A/0 and Bardenpho processes involve mainstream (influ-
ent flow plus sludge recycle) anaerobic treatment to pre-condi-
tion the system for phosphorus removal via waste activated
sludge.
The A/0 process can be designed for phosphorus removal with-
out nitrification by use of anaerobic/oxic stages, or for phos-
phorus removal with nitrification by use of anaerobic/anoxic/ox-
ic stages plus additional internal mixed liquor recycle from the
oxic to the anoxic stage. The Bardenpho system is a five-stage
(anaerobic/anoxic/aeration/anoxic/reaeration) process designed
to provide both phosphorus and total nitrogen removal.
The development status of these processes (including a list
of pilot studies and full-scale installations), process theory,
capabilities, and design considerations are addressed in this
report.
IV
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Related capital, O&M, and total present worth costs for
these three processes, as well as for baseline technology of
coventional activated sludge (one, two, or three-stage system
depending on the degree of nitrogen removal required) with alum
addition, were estimated to provide a reasonable basis for
alternative comparison. Based on these estimates and assump-
tions of the tote L present worth costs, the three proprietary
processes are found to be cost-effective and particularly
applicable under the following conditions:
PhoStrip process for effluent residual total phos-
phorus for large treatment plants.
* A/O process for effluent residual total phosphorus
at all plant sizes.
» Modified A/O process for effluent residual total
phosphorus oE 2 mg/L and 1 rag/L ammonia nitrogen
at all plant sizes.
Bardenpho process for effluent residual total phos-
phorus of 2 mg/L and total nitrogen of about 3 mg/L
at all plant sizes.
Market potential for these three processes (based on a
needs survey in the U.S.), and their costs and energy impacts
are addressed in the report. Further research and development
efforts and potential areas for process modifications are also
identified.
Appendix C contains the response of the three proprietary
firms to this report.
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CONTENTS
Foreword
Abstract
Figures.
Acknowledgements ..... ....... ....... V111
*"**«» ..... ix
1. Technology Description ........ . ,
Introduction. .....****** 7
..
Technology descriptions . '. '. '.
PhoStrip process ......
A/O process (anaerobic/oxic)
Bardenpho process. ....
2. Technology Evaluation .......
Process theory. . . ....... *-..... y
Process capability and limitations." III.*""* i?
Design considerations ....... .... * * 14
PhoStrip process ..... ***-. J.
A/0 process. . . ..... .."[.* ...... tfi
Bardenpho process ...... II!!!]**" YJ
Operations and maintenance considerations . I 20
3. Development Status ........... ° ^"
PhoStrip process. ..... I I I ..... * * * ^
A/O process . ....... ! I I I ***"""" of
Bardenpho process ..... I " * * ....... po
4. Comparison with Equivalent Technologies! Ill*"* 33
Equivalent conventional concept ... * a-i
Cost comparison . ...... ...******* ^f
Energy requirements . ..... ......... ^
5. Assessment of National Impact. ..." * ...... c?
Market potential .......... Ill**"" 51
Costs and energy impacts. .. I I I I """*** ct
Risk assessment ......... I I * " * * * * cc
6. Recommendations. .. ..... III! ...... * c^
Future research and development efforts I " " * * sfi
Process/ technology modifications ...... .* * 57
References ...........
Appendices «... ..... . ..... 59
A. - Cost and energy analysis assumptions. ... 66
a. - Lost comparison and energy analysis . * ji
C. - Response of proprietary firms. .
VI
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FIGURES
Number page
1 PhoStrip Process Flow Diagram ........... 4
2 (a) A/0 Process Plow Diagram for Phosphorus Removal . . 6
2(b) A/O for Phosphorus Removal with Nitrification/De-
nitrifieation 6
3 Baraenpho Process Flow Diagram. ..... 8
4 Biological Phosphorus and BOD Removal Due to
Anaerobic-Aerobic Contacting (Adapted from
Reference 17) . 10
5(a) Capital Cost Comparison Case 1: Phosphorus Re-
moval (Effluent TP = 1 mg/L) ........... 43
5 (b) O&M cost comparison - Case 1: phosphorus Removal
(Effluent TP = 1 mg/L) 44
6(a) Capital Cost Comparison case 2: Phosphorus Re-
moval (Effluent TP = 2 mg/L) ........... 45
6(b) O&M cost Comparison Case 2; Phosphorus Removal
{Effluent TP = 2 mg/L) . 46
7 (a) Capital Cost Comparison -- Case 3: Phosphorus Re-
moval and Nitrification (Effluent TP = 2 mg/L,
NH3-N = 1 mg/L) ................. 47
7(b) O&M cost comparison Case 3; Phosphorus Removal
and Nitrification (Affluent TP = 2 mg/L, NH^-N » I
mg/L). 7 ... 48
8(a) Capital Cost Comparison case 4: Phosphorus Re-
moval i Nitrification, and Denitrification (Effluent
TP = 2 mg/L, TN = 3 mg/L) ............ 49
8(b) O&M Cost Comparison -- Case 4: Phosphorus Removal,
Nitrification, and Denitrification (Effluent TP =
2 mg/L, TN = 3 mg/L) ............... 50
VII
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TABLES
Number Page
1 PhoStrip Process Pilot and Full-Scale Plant
Operations Data. ..... , 22
2 A/0 Process Pilot and Full-Scale Plant Opera-
tions Data .............. 25
3 Bardenpho Process Pilot and Full-Scale Plant
Operations Data. ..... . 29
4 Alternative Cases Evaluated Under Technology As-
sessment of Biological Phosphorus Removal. .... 34
5 Summary of Cost Comparison Case 1: Phosphorus
Removal (Effluent TP = 1 mg/L) 37
6 Summary of Cost Comparison -- Case 2: Phosphorus
Removal (Effluent TP = 2 mg/L) .......... 38
7 Summary of Cost Comparison Case 3: Phosphorus
Removal and Nitrification (Effluent TP = 2 nig/L,
HH3-N = 1 mg/L) 39
8 Summary of Cost Comparison Case 4: Phosphorus
Removal and Nitrification/Denitrification (Efflu-
ent TP = 2 ag/L, TN =* 3 mg/L) . 40
9 Summary of Least Cose Alternatives. 41
10 Summary of Energy Requirements in 10 kwh/year. . . 42
11 Facilities Designed to Provide Advanced Waste-
water Treatment (AWT) for all States and U.S.
Territories 52
12 National Dollar Needs for Changes in Existing
Treatment Plants and for Construction of New Ad-
vanced Wastewater Treatment (AWT) Facilities ... 54
Vlli
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ACKNOWLEDGEMENTS
This report was prepared by Dr. Larry Y. H. Lin of Roy F.
Weston, Inc. and reviewed by Dr. M. Ramanathan, Anthony J.
DeFalco, and Glenn M. Johnson from the technical aspect.
The cooperation of the U.S. EPA Municipal Environmental Re-
search Laboratory staff throughout the preparation of this re-
port is gratefully acknowledged. We are indebted to Mr. Gary R.
Lubin, who served as Project Officer during this effort, for his
coordination and guidance in completing this assignment. Partic-
ular appreciation is extended to Mr. Edwin F. Barth who provided
a detailed review of this report as well as numerous comments
and valuable input.
The technical assistance provided by the following persons
was appreciated in preparing the technology description and de-
velopment status of the three proprietary biological phosphorus
removal processes:
Biospherics Incorporated - Dr. Gilbert V. Levin
Mr. Tony Kish
9 Air Products and Chemicalsf Inc. - Dr. David J. Krichten
Dr. Sun-Nan Hong
EIMCO Process Machinery Division
of Envirotech Corp. - Mr. David DiGregorio
Dr. H. David Stensel (University of Utah)
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SECTION 1
TECHNOLOGY DESCRIPTION
INTRODUCTION
For the past two decades, phosphorus has been recognized as
a major limiting factor (along with nitrogen) in the control of
eutrophication due to excessive algae and aquatic vegetative
growth in streams and lakes. In response to this effect, pollu-
tion control agencies have instituted stringent limitations
controlling nutrient discharge into receiving waters. Examples
are the Great Lakes regions, the Florida Tampa Bay region, Lake
Tahoe, and the Chesapeake Bay area (1). Typical effluent stand-
ards have been 1 mg/L and 3 mg/L for phosphorus and total nitro-
gen, respectively. Less stringent requirements are also adopted
in various localities to meet water quality standards.
Since the early 1970's, chemical precipitation with either
alum, ferric chloride, or lime has been the widely used as a
demonstrated technology for phosphorus removal (2). Where possi-
ble, steel mill waste pickle liquor has provided a relatively
inexpensive chemical source for phosphorus precipitation, al-
though it may also contain other undesirable heavy metals. The
disadvantages of chemical precipitation treatment for phospho-
rus removal are chemical costs, chemical handling and storage
requirements, increased sludge production, and related sludge
handling and disposal costs.
Prior to the present application of specifically designed
biological phosphorus removal systems, a series of studies and
full-scale plant observations on biological phosphorus removal
had been reported. In 1955, Greenburg et al. (3) proposed that
activated sludge could take up phosphorus at a level beyond its
normal microbial growth requirements. Srinath et al. (4) report-
ed in 1959 that soluble phosphorus in mixed liquor (aqueous
phase) decreases rapidly to below 1 mg/L under varying condi-
tions of aeration. However, Levin and Shapiro (5) in 1965 were
the first to associate excess biological phosphorus removal, now
called "luxury uptake,*1 with anaerobic/aerobic sequencing of
biological treatment systems, which is currently the accepted
mechanism. This led to intensive studies of the possible appli-
cation of this phenomenon for removal of phosphorus in activated
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sludge plants 16, 7, 8, 9, 10). It appeared that all the plants
that successfully removed phosphorus were high-rate, non-nitri-
fying, plug-flow type activated sludge plants. By the early
1970's, three distinct proprietary biological phosphorus removal
processes had been developed; namely, the PhoStrip process by
Levin et al. {11, 12, 13), the Bardenpho process by Barnard of
South Africa (14, 15), and the A/0 process by Air Products and
Chemicals, Inc. (16, 17). These three commercial biological
phosphorus removal processes are currently patented and marketed
in the United States by the following companies:
PhoStrip - Biospherics, Inc.
A/O - Air Products and Chemicals, Inc.
Bardenpho - EIMCO Process Machinery Division of
Envirotech Corporation
In addition to the three major proprietary processes dis-
cussed in this report, a number of other modifications to the
biological phosphorus removal system have been proposed. They
include:
The UTC (University of Capetown) process described
by Siebritz, Ekama and Marais (18) for application
to wastewaters with relatively high total Kjeldahl
nitrogen to chemical oxygen demand (TKN/COD) ra-
tios.
The "safe" design optimization approach proposed by
Mulbarger and Prober (19), which can be various
combinations of primary chemical treatment, anaero-
bic and aerobic contacting as in the A/0, PhcStrip
with lime addition, and metal salts addition in the
aeration basin for polishing phosphorus to low lev-
els.
The biological phosphorus removal with "roughing"
chemical treatment proposed by Stensel (1), which
is a modified anaerobic contactor design similar
to a combination of the Bardenpho or A/O with the
PhoStrip system.
These modified processes can be applicable to certain spe-
cific cases; however, they are not included in the technical as-
sessment within this report due to the complexity of the subject
and their limited available development data.
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The Clean Water Act (PL 95-217} mandated that an analysis
and evaluation of innovative and alternative technologies be
conducted during the development of federally-funded wastewater
management projects (21, 22}. This requirement, administered
through the U.S. Environmental Protection Agency's (EPA) Con-
struction Grants Program, has encouraged the development of
several new treatment processes having potential for applica-
tion in municipal wastewater treatment practice. In order to as-
sess the status of development and the capabilities of these
"emerging" technologies, EPA has initiated a series of technol-
ogy assessments for evaluating these processes. This technology
assessment report is prepared to evaluate the three patented
processes for biological phosphorus removal, which are currently
gaining in acceptance and applications.
TECHNOJJOGY DESCRIPTIONS
PhoStrip Process
The PhoStrip process was first proposed by Gilbert Levin in
1965 (5, 6) and is currently marketed by Biospherics, Inc. This
process is an activated sludge process that takes advantages of
"luxury" phosphorus uptake and anaerobic phosphorus release. A
schematic flow diagram of the PnoStrip process is presented in
Figure 1. This process differs from conventional activated
sludge in that a portion of the return sludge is subjected to
"phosphorus stripping" by holding the sludge under anaerobic
conditions in a stripper tank. The solids retention time (SET)
in this tank typically ranges from 8 to 12 hours. During this
anaerobic period, phosphorus is released and is elutriated from
the sludge in the stripper tank with a stream that is low in
phosphorus content. This stream may either be the overflow from
the chemical treatment tank (reactor clarifier) as is shown in
Figure 1, or primary effluent. The phosphorus-rich overflow
from the stripper tank passes continuously to the chemical
treatment tank where lime is added for phosphorus precipitation.-
Because of the flexibility of the percent of return sludge
that can be subjected to anaerobic conditions for different
detention times in the stripper tank, a wide range of phos-
phorus removal can be achieved. Control of the side-stream
permits phosphorus removal to be divided between stripper super-
natant and waste activated sludge (13).
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Influent
CO)
Primary
Sludge
Direct Sludge Recycle
(0,2 to 0.50)
Phosphorus-
Enrichecf
Sludge
(0.2 Co 0.3QJ
Effluent
Waste
fci Activated
Sludge
Anaerobic
Phosphorus
Stripper
L« c -- ElubiaUon from any oft
_. - ,
Chemical \
Sludge
Stripper
Underflow
(0.1 to 0.2Q)
(a) Stripper Underflow Recycle
(b) Primary Effluent
{ci Reactor - Clarifier Supernatant
Figure 1. PhoStrip process flow diagram.
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A/0 Process (Anaerobic/Oxic)
The A/O process was developed by Air Products and Chemicals,
Inc. for the removal of phosphorus and/or nitrogen from wastewa-
ter (16, 17). The A/0 process is a single-sludge, suspended
growth system that can combine anaerobic, anoxic-S and aero-
bic sections in sequence. Figure 2(a) is a schematic represen-
tation of the A/O process for phosphorus removal. The process
can be designed for phosphorus removal with or without nitrifi-
cation and denitrification. All sections are partitioned into
several hydraulic stages to approach plug-flow and prevent back-
mixing. Typically, for removal of phosphorus, three anaerobic
stages are followed by three or more aerobic or oxic stages.
Recycled sludge from the secondary clarifier is mixed with
either raw wastewater or primary effluent in the anaerobic
section so that there is "sorption" of BOD by the organisms,
with accompanying phosphorus release necessary for biological
phosphorus removal. The anaerobic section is covered and equip-
ped with mechanical mixers for mixing but not aeration.
The oxic stage, essential for the metabolism of BOD and up-
take of the phosphorus released in the anaerobic stage, may be
aerated with either air or oxygen. Phosphorus is removed from
the system in the waste sludge, which may contain 4- to 6-per-
cent phosphorus by dry weight. Effluent phosphorus concentra-
tions are dependent on sludge wasting, which in turn is control-
led by the plant's operating solids residence time (SRT) .
When necessary, nitrification can be accomplished in the
oxic section by operation at a properly selected solids resi-
dence time and organic loading suitable for growth of nitri-
fying bacteria. When denitrification is further required, the
anoxic section is included between an anaerobic and oxic sec-
tion as shown in Figure 2(b). The anoxic section is deficient
in dissolved oxygen, but chemically-bound oxygen in the form of
nitrate or nitrite is introduced by recycling nitrified mixed
liquor from the oxic section back to the anoxic section.
term "anaerobic" refers to environments that have no
measurable concentrations of either dissolved oxygen or oxi-
dized nitrogen in the form of nitrate or nitrite; "anoxic"
refers to environments that have no dissolved oxygen, but can
have oxidized nitrogen present.
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Influent or (Q) _
Primary Effluent
i
^
1
1
1
I
(
I
1
1
1
1 1 I
I | I
! i
1 1
1 I I
Anaerobic 1 Qxic
j*1 1 uiai
Sludge Recycle
Effluent
Waste Aciivated Sludge
(Phosphorus-Rich)
i Figure 2(a). A/O process flow diagram for phosphorus removal.
Influent or (Q)
Primary Effluent
Internal Recycle
(20)
Sludge Recycle
Effluent
Waste Activated Sludge
{Phosphorus-Rich}
Figure 2{b). A/O for phosphorus removal with nilriftcation/deniirification.
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Bardenpho process
The Bardenpho process was first Investigated in Pretoria,
South Africa by Jaraes Barnard in the early 1970 "s (14). Barden-
pho stands for Barnard-denitr ification-phosphorus, an activated
sludge process designed to accomplish both biological phosphorus
uptake and nitrogen removal. The process is patented by the
South African inventions Development Corporation and licensed to
Envirotech corporation for marketing in the United States. The
Bardenpho process is very similar to the previously described
&/O processf except there is an additional anoxic and a reaera-
tion section at the tail end.
As shown in Figure 3, two anoxic stages are used to accom-
plish high levels of biological nitrogen removal by denitrifi-
cation. An anaerobic stage is added ahead of the original four-
stage Bardenpho nitrogen removal system to create anaerobic-aer-
obic contacting conditions necessary for biological phosphorus
uptake. Return activated sludge, separated from the clarifier,
is mixed with the influent wastewater prior to the anaerobic
contactor, which is to initiate luxury phosphorus uptake by
first releasing phosphate. Mixed liquor from the anaerobic con-
tactor then flows into the first anoxic denitrification zone
where it is mixed with an internally recycled mixed liquor from
the aerobic nitrification zone. In the first anoxic denitrifica-
tion zone, nitrate is reduced to nitrogen gas using soluble or-
ganic matter in the wastewater as a carbon source. The mixed
liquor then flows into the aerobic nitrification zone where lux-
ury phosphorus uptake, ammonia oxidation, and additional BOD re-
moval occurs. Following the aerobic nitrification zone, a second
anoxic zone provides additional denitrification, which is de-
signed to remove additional nitrate and minimize nitrate feed-
back to the anaerobic contactor. The reaeration zone provides
oxidation of remaining ammonia and raises dissolved oxygen
levels for effluent discharge.
Phosphorus is removed from the system in the waste sludge,
which may contain 4- to 6-percent phosphorus by dry weight.
Depending on the relative amounts of phosphorus, BOD, and ni-
trogen in the influent, low levels of phosphorus (less than 1
mg/L) can be achieved in the effluent. For weaker wastewaters
or high influent phosphorus concentrations, a small amount of
chemicals, such as alum or ferric salts, are added to polish
the effluent phosphorus to below 1 mg/L, if required. Because
of the liquid detention times and SET required for nitrification
and denitrification, a relatively high-quality effluent in terms
of BOD, suspended solids, and ammonium nitrogen concentrations
is possible. The resultant SET provides an aerobically-stabi-
lized sludge that has been disposed of without further stabili-
zation (1).
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Internal Recycle
WO)
Influent
Anaerobic
Anoxic I Aeration
(Devitrification) (Nilrificalion)
Anoxic
Reaeralion
Sludge Recycle
Waste Activated Sludge
(Phosphorus-Rich)
Figure 3. Bardenpho process flow diagram.
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SECTION 2
TECHNOLOGY EVALUATION
PROCESS THEORY
Phosphorus in raw wastewaters exists in three forms: ortho-
phosphate {£04), poly-phosphate ^307)i and organic phos-
phorus (47). The ortho-phosphorus can be readily assimilated by
microorganisms, and the poly- and organic phosphorus forms are
usually hydrolyzed by microorganisms to the ortho form. Phos-
phorus is an important element for microorganisms due to its use
in energy transfer and for cell components such as phospholip-
ids, tmcleotides, and nucleic acids. The amount of phosphorus
removed due to sludge wasting may be in the range of 10 to 30
percent of the influent amount for typical secondary treatment
employing the activated sludge process.
The phoStrip, A/O, and Bardenpho processes were all develop-
ed in the early 1970's by utilizing essentially the same mechan-
ism of enhanced biological phosphorus removal (or the so-called
"luxury" uptake} in activated sludge systems, which is created
by cyclic stressing of the system to anaerobic (i.e., absence of
molecular oxygen, nitrate, or nitrite) and aerobic conditions.
This mechanism takes advantage of the fact that phosphorus is
released by microorganisms under anaerobic (starved) conditions
and subsequently incorporated to a higher cellular content
(luxury) under aerobic conditions.
Tne biological phosphorus and BOD removal due to anaerobic-
aerobic contacting in the A/0 process is depicted in Figure 4.
The A/0 process initially mixes the full forward influent and
recycle sludge under anaerobic conditions to influence selec-
tion of microbial population favoraole to such phosphorus re-
moval mechanism (17). Phosphorus is removed from the system
through wasting of activated sludge that is rich in phosphorus
content. The phosphorus levels in the waste activated sludge
from the A/0 process typically reach 4 to 6 percent by dry
weight, as compared to 2 to 3 percent in conventional activated
sludge.
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Influent
r_ _ _ Return Sludge
Anaerobic
Aerobic
ToCfarifier
c
1
4-*
CD
O
O
O
CO
3
h*
O
§.
in
O
0-
O
O
Space Time
Figure 4. Biological phosphorus and BOD removal due to anaerobic
aerobic contacting (Adopted from Ref. 17).
10
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In the case of the PhoStrip process, a portion of the return
activated sludge is routed to an "anaerobic stripper" tank where
the microorganisms release soluble phosphorus. The stripper tank
supernatant, which is only a fraction of the total wastewater
flow, needs proportionally lower amounts of lime to precipitate
the phosphorus in this flow. The supernatant and lime mixture
may then be routed to the primary clarifier or a separate re-
actor-clarifier for removal of the precipitated sludge. "She
phosphorus-depleted sludge from the stripper is returned to the
aeration basin, where the microorganisms take up phosphorus un-
der aerobic conditions (13). Part of the phosphorus is also re-
moved from the system through the waste activated sludge route.
The relative amounts of phosphorus removed through the two exit
points can depend on wastewater characteristics (particularly
the relative concentrations of BOD and phosphorus in the influ-
ent) as well as design and operation of a specific system.
In the Bardenpho process, Barnard (14) found that higher-
level phosphorus removal from wastewater occurred during aera-
tion of sludge that was subjected to anaerobic contacting! thus,
he added an anaerobic contacting stage ahead of the four-stage
(anoxic-aeration-anoxic-reaeration) system originally devised
for nitrogen removal, Barnard also found that nitrates in the
recycle flow to the anaerobic zone could prevent phosphorus re-
lease and reduce the high levels of phosphorus uptake in the
aerobic zone? thus, the internal recycle of mixed liquor from
the aerobic to the anoxic zone (see Figure 3) to remove the ni-
trate is also important from the standpoint of maintaining an-
aerobic conditions in the first stage. As in the case of &/Q,
the full forward influent flow and recycle sludge are subjected
to anaerobic treatment, and the phosphorus is removed from the
system through sludge wasting. Thus, of the three proprietary
systems, PhoStrip is a sidestream treatment process, while A/O
and Bardenpho are mainstream treatment processes.
The anaerobic-aerobic staging apparently results in the se-
lection of a biological population that is capable of achieving
phosphorus removal. The actual mechanism for the phosphorus
storage and release is not fully known, nor is the basis for the
phosphorus removal population selection. This is partly due to
the complexity of the many factors involved, and to the lack of
complete quantitative fundamental :>ialysis of the biological
phenomena. The following lists tn<* various empirical observa-
tions reported for the occurrence of biological phosphorus re-
moval (1) :
Phosphorus release occurs under anaerobic contact-
ing, with mixed liquor soluble phosphorus reported
in the range of 20 to 40 mg/i».
-------
Phosphorus uptake occurs rapidly under subsequent
aerobic conditions to produce low mixea liquor
soluble phosphorus concentrations.
The increased phosphorus taken up appears to be
stored as polyphosphates in the cell, or contained
in volutin granules within the cell. The volutin
granules contain lipidsf protein, RNA, and magne-
sium, in addition to polyphosphates. volutin is
used for nucleic acid synthesis and may be released
as orthophosphate to meet metabolic requirements
of the cell (5, 48, 49, 50, 51).
The synthesis and degradation of poly-beta-hydroxy-
butyrate (PHB), which is an intracellular carbon
storage product, can play a role in the biological
phosphorus removal (52 through 60}.
* Acinetobactor (a grain-negative, aerobic bacteria)
has been "frequently found in biological phosphorus
removal systems and is known to store polyphosphate
(61, 50, 53, 54, 55). However, glucose is not as-
similated by Ac inetobactor. Other types of poly-
phosphate-storing bacteria, including certain gram-
positive species, Aeromonas, pseuaomonas, and fac-
ultative bacteria, have also been found to exist in
biological phosphorus removal systems (49, 62, 63).
* Significant levels (over 70 percent) of influent
soluble BOD could be taken up by the microorgan-
isms in the initial anaerobic stage. Aeration-
stage oxygen uptake rates are lower in anaerobic-
aerobic systems than in conventional activated
sludge systems. This can be due to the accumulation
of storage products such as PHB within the cells
during the anaerobic stage, thereby extending the
period of oxidation of the carbon source {57, 58).
The presence of nitrates or oxygen in the anaero-
bic stage will prevent phosphorus release and sub-
sequent biological phosphorus removal. Methods
available to mitigate this effect include:
Feeding high BOD strength wastewater to the sys-
tem to rapidly deplete any dissolved oxygen.
Avoiding any recycling of nitrified effluent or
sludge containing nitrate back to the anaerobic
stage.
-------
- Proyiding removal of nitrate by separate-stage
devitrification, if nitrification is also re-
quired.
Extending the period of anaerobic contacting, if
necessary, to provide residence time for deni-
trific
trification.
PROCESS CAPABILITY AND LIMITATIONS
panaM fc5ree pr?Priefcary Processes have been demonstrated as
malfv loundTOV1^ ?ho*Phorus fr^ ^e 4 to 12 rag/L range nor-
mally found in municipal wastewaters (20) down to the 1 to 2
e?f?LS it0ta^ ?hosPhorus <«» " is important to con-
effluent limitations in each specific case to determine
S^11^0^3011 °f these P«*>««es. For exaJS^JSe
« t 3*d Plor/lda-TamPa Bay Region call for effluent
limitations of 1 mq/L as TP, while some areas in South Africa
have a standard of less than I mg/L of ortho-phSspSate
A*- aS fi, ce these Presses are often "marginal" in
Sa/?Ua«nmefp1Ue?H qUalit? °f less than l to 2 m
-------
The A/O process can be used for phosphorus removal with or
without nitrification. Concentrations of total phosphorus in the
treated effluent are usually in the range of 1.5 to 3.0 mg/L
(see Table 2 in Section 3). Since significant amounts of efflu-
ent phosphorus are associated with the suspended solids, efflu-
ent filters would become necessary if total phosphorus at 1 mg/L
is to be met. It is possible that the A/0 process can be design-
ed also for denitrification. However, operations at Largo showed
that only partial denitrification was achieved. The capability
of the A/0 process to provide phosphorus removal, as well as
complete nitrificacation/denitrification, remains to be demon-
strated. It should be noted that phosphorus-rich waste activated
sludge is generated from the A/Q process. The sludge should be
further stabilized to remove degradable portions of volatile
solids by either aerobic or anaerobic digestion. In particular,
when anaerobic digestion is used, the digested liquor would
contain high concentrations of phosphorus, and it should not be
returned to the front end of the A/0 system without chemical
treatment to precipitate the phosphorus. Air Products estimates
that for each 37,850 m3 (10 million gallons) of wastewater
treated, 1.0 to 1.5 tons (2,000 to 3,000 Ib) of lime are re-
quired for anaerobically-digested sludge, and 0.33 ton (660 lb)
of lime is required for aerobically-digested sludge (17).
The Bardenpho process is applicable when removal of Doth the
phosphorus and total nitrogen is necessary. This process is not
normally used when only phosphorus removal is required. The cap-
ability of the Bardenpho process to consistently produce total
phosphorus of less than 2 mg/L, or soluble phosphate of less
than 1 mg/L as P, without supplemental mineral addition, remains
to be demonstrated (see Table 3 in Section 3). Effluent filters
would probably be needed if total phosphorus in the effluent is
to be reduced to less than 1 mg/L. Since solids residence time
(SRI) in the Bardenpho process is typically maintained near 20
days and can be as long as 40 days, the excess sludge wasted
from the system is reasonably well stabilized.
DESIGN CONSIDERATIONS
Since PhoStrip, A/O, and Bardenpho are all proprietary proc-
esses, respective consultation from Biospherics, Air Products,
or EIMCO should be sought when designing a specific biological
phosphorus removal system. Typical design parameters and other
considerations important to each of the three processes are pre-
sented in the following paragraphs.
14
-------
PhoStrip Process
Brass--
Influent BOD5 = ?o to 300 mg/L.
Influent TP = 3 to 20 mg/L.
Wastewater temperature = 10 to 30°C.
Secondary clarifier NO3-N pius NOo-N = l t-n in
??£uo^
Scours? detenti°" time in aeration basin = 1 to
MLSS = 600 to 5,000 mg/L.
PhoStrip design parameters are as follows:
Refer to Figure 1.
* t^ofa"?111 retUrn SlUdge flow to be treated = 0.2
* t?mer-b|Ctnh?fPh°rUS friPPer sl^ge retention
time -8 to 12 hours (elevated NO-,/NCH-N con-
centrations require a 50 percent incrlase in SRT) .
» Stripper SWD = 6.1 m (20 ft).
Stripper sludge blanket depth = 4.6 m {15 ft).
Elutriation flow = 50 to 100 percent of the
per feed by one of the three sources:
ef,o-
ettluent e
Reactor-clarifier overflow elutriation.
recycle to aeration basin - 0.1
15
-------
Stripper supernatant to reactor-clarifier = 0.1 to
0.2 Q.
Reactor-clarifier overflow rate = 49 m3/m2/d
(1,200 gpd/sq ft).
Reactor-clarifier pH = 9.
Lime dosage = 100 to 300 mg/L, depending on alka-
linity concentration in stripper supernatant.
A/O Process
Mr Products (17) has developed a bio-kinetic simulation
model that can predict the soluble phosphorus and BOD removal
performance of a treatment plant under a given set of condi-
tions. This model has been tested using the Largo A/0 pilot-
plant and full-scale plant data with good correlation.
Typical design parameters for the two A/O systems (33) are
as fallows:
BOD and p BG0, p, and N
Parameter removal removal
Detention time, hrs
Anaerobic stage 0.5-1.0 0.5-1.0
Anoxic stage 0.5-1.0
Oxic stage 1-3 3.5-6
F/M,
kg BODs/day/kg MLVSS 0.2-0.6 0.15-0.25
(Ibs BQD5/day/lb MLVSS) {0.2-0.6) (0.15-0.25)
MLVSS, mg/L 2,000-4,000 3,000-5,000
Oxygen usage,
kg O2/kg BODs removed 1.0 1.2
(Ibs O2/lb BODs removed) {1.0} (1.2)
Return sludge flow, % of
influent Q 10-30 20-50
Underflow concentration,
% solids 2-4 1.5-3.0
Internal recycle, % of
influent Q 100-300
16
-------
BOD and P BOD, P, and N
Parameter removal removal
Minimum D.O. (oxic stage) »
2. 0 2.0
Sludge wasted,
kg/kg BOD5 removed 0.5-0.8 0.3-0.6
(Ibs/lb BOD 5 removed) (0.5-0.8) (0.3-0.6)
Mixing energy (anaerobic) ,
kw/1,000 m3 10 10
(hp/1,000 gal) (0.05) (0.05)
Temperature, °C 5-30 5-30
Normally suggested formats for baffled staging of the A/O
system are three anaerobic stages , three anoxie stages, and
four oxic (aerobic) stages. The anoxie stages and the internal
recycle are used only if nitrogen removal (i.e., nitrification/
denitrification) is required. The anerobic and anoxie zones are
provided with mixers and covers to avoid exposure to the atmos-
phere. The size of the oxic stage depends on nitrification re-
quirements. Without oxidation of nitrogen, a hydraulic detention
time of 2 to 2.5 hours is recommended. With nitrification, the
oxic stages must be enlarged to 3.5 to 6 hours, depending on
nitrification rate and temperature. The final clarifiers are
normally designed at an overflow rate of 24.5 m^/m^/d (600
gpd/sq ft), with a desired sludge blanket depth of below 0.6 m
(2 ft) . Attention should be paid to possible phosphorus bleed-
back within the sludge blanket due to anaerobic conditions. Use
of a hydraulic bottom sweep to rapidly remove the sludge can
help to mitigate phosphorus bleedback in this area. Maximum
design return sludge recycle is 50 to 75 percent of influent
flow.
Bardenpho Process
The Bardenpho process design approach must evaluate design
requirements for each of the five stages to accomplish phosphor-
us removal, nitrification, and denitrification. The detention
time in each of the five stages is affected by 8005 and total
nitrogen concentration, wastewater temperature, effluent re-
quirements, and sludge handling considerations. Typical design
detention times, based on influent flow, for the five stages,
are as follows:
17
-------
Stage
11 plants in
South Africa
[Reference 44)
Range &vg.
Detention Hrae, hours
Palmetto/
Florida
(Reference 38)
Design Actual
Kelownar
Canada
(Reference 1)
Design
Anaerobic
First Anoxie
Aeration
(Nitrification)
Second Anoxic
Heaeration
Total
0.6- 1.9 1.3
2.2- 5.2 3.2
6.7-19.0 11.2
2.2- 5.7 3.3
0.5- 1.6 1.1
12.2-33.4 20.1
1.0
2.7
4.7
2.2
1.0
11.6
1.4
3.8
6.6
3.0
1.4
16.2
2
4
9
4
2
21
Sludge disposal considerations may affect the process de-
sign sizing. For example, many Bardenpho system designs, which
are based on achieving nitrification and denitrifieation, may
result in a final SRT that may be within the range of sludge
stabilization by aerobic digestion. In such cases, design SRT
values are increased by increasing the detention times of the
aeration tanks to achieve a stable sludge in addition to
nitrogen, BOD, phosphorus, and suspended solids removal (1).
The first step in the Bardenpho design is to review the fac-
tors that will determine the amount of biological phosphorus
removal. Phosphorus removal will therefore depend on the amount
of sludge wasted and the percent phosphorus content of the
sludge. The influent 6005 concentration and system SRT will
determine sludge production. The percent phosphorus in the
waste sludge may be affected by the anaerobic zone detention
time, as well as the influent soluble 6005 concentration. The
amount of nitrate or dissolved oxygen in the recycle streams to
the anaerobic zone must be minimal for effective phosphorus re-
moval. The sludge wasting techniques must also be evaluated to
maximize phosphorus removal from the system. Sludge processing
and wasting techniques that result in leaching of phosphorus
from the biological cells, and the subsequent return of this
leached phosphorus to the Bardenpho system, will reduce phos-
phorus removal efficiency. Bardenpho sludges have been wasted
to drying beds, applied on land, or thickened by dissolved air
flotation prior to dewatering to minimize phosphorus release
(1).
18
-------
The first anoxic design follows a nitrogen balance performed
for the system. This balance determines the amount of nitrogen
oxidized by subtracting from the influent nitrogen, the nitro-
gen used for cell synthesis and the ammonium nitrogen in the ef-
fluent. Using a four to one internal recycle rate, two-thirds
of the ammonium nitrogen oxidized in the nitrification stage is
then directed to the first anoxic stage. The first anoxic stage
is designed for complete denitrification of the recycled ni-
trate t and its volume is a function of the MISS concentration
and specific denitrification rate (64) .
The remaining nitrate is denitrified in the second anoxic
stage. The specific denitrification rate (64) has been described
for this stage as a function of the endogenous respiration rate
of the mixed liquor. This will be a function of the system SET,
temperature, and active fraction of the mixed liquor suspended
solids. The volume for the second anoxic stage is then deter-
mined by the amount of nitrate that must be reduced, the specif-
ic denitrification rate, and the system MISS concentration.
The first step in the nitrification stage design is the
selection of the necessary nitrification SRT as a function of
wastewater temperature. A minimal nitrification SRT predicted
by Knowles (65) may be used with a 2 or 3 safety factor multi-
plier depending on peak to average flow conditions expected.
The nitrification stage SRT is then determined using the follow-
ing equation;
(MLSS) V
SRT = n
n ₯ (&BQD) Q
where:
SRTn = Nitrification stage design SRT, day.
MLSS = Mixed liquor suspended solids, mq/L.
Vn =» Nitrification stage volume, m3 (million gallons).
Yn = Net system sludge yield based on overall system
SRT, kg SS/kg BOD5 removed (Ibs SS/lb BODs
removed).
AsOD = BOD removal in system, mg/L.
Q = Wastewater flow, m3/d (mgd).
The total system SRT is based on all of the stages where
biological growth can occur, and not just the nitrification
stage. The net sludge yield includes cell synthesis and
endogenous decay.
19
-------
Oxygen requirements for the nitrification aeration stage are
based on the amount of BOD removed, the net kg C>2/kg BOD5
removed (Ibs 02/lb BODs removed) based on the total system
SRT, and the oxygen required to oxidize the ammonium nitrogen
minus a credit for the equivalent oxygen available during ni-
trate reduction. The reaeration stage is designed both to strip
enmeshed nitrogen gas bubbles from the floe matrix and to raise
the mixed liquor dissolved oxygen concentration to at least 2
mg/L or higher as determined by effluent requirements.
The above design approach may involve iterations until the
desired overall system SET is met with regard to sludge aerobic
stabilization needs. If the sludge is to be stabilized by addi-
tional steps or handled in a different manner, then the volume
of the stages will be determined only by nitrification and
denitrification needs (1).
The anaerobic contact detention time is presently based on
experience. The importance of sufficient carbon for the removal
of nitrates has been stressed by Barnard (45)« It would appear
that at a CODrTKN ratio of above 10, there are no problems in
reducing the nitrates and inducing the removal of phosphorus.
Primary sedimentation could change this ratio, and the degree
of such removal must be determined. When there is sufficient
carbon, some form of high rate primary sedimentation may be
economical, and this has been applied in some plants. On the
other hand, if the wastewater is weak and there is insufficient
carbon to induce anaerobic conditions, provisions should be
made to bypass the primary clarifier and to pass only part of
the return sludge to the anaerobic zone, while bypassing the
remainder to the anoxic zone, provision of flow equalization
ahead of the system can also serve to avoid the short detention
time in the anaerobic contact zone during peak hydraulic flow.
OPERATIONS AND MAINTENANCE CONSIDERATIONS
In general, the three proprietary processes for phosphorus
removal are not appreciably different from the equivalent con-
ventional activated sludge process with mineral addition. A
number of various mechanical problems have been experienced in
all three types of plants, which have caused either delay in
startup or interruptions in stable operation. These problems
are more related to mechanical design and selection of equip-
ment than to the process itself. However, process problems can
be induced due to mechanical problems. Therefore, higher stand-
ards of operator training and a greater theoretical knowledge
of the process on the part of operators than those for conven-
tional activated sludge plants are required. The Bardenpho proc-
ess is more complicated than PhoStrip or &/Q (without nitrifi-
cation) from the process standpoint, since the former involves
both phosphorus and nitrogen removal. The relatively highly
skilled staff and large number of sample analyses required for
successful operation of a biological phosphorus removal system
could well be a major burden for some small plants (44).
20
-------
SECTION 3
DEVELOPMENT STATUS
PHOSTRIP PROCESS
Since the concept of the PhoStrip proce: i was devised in
1965 by Levin (5), many pilot studies and plant-scale demonstra-
tion tests had been conducted in the early 1970's to substanti-
ate the applicability of this process under various operating
conditions. In addition, over a dozen full-scale plants employ-
ing the PhoStrip process have been constructed, many of them in-
volving retrofitting of existing facilities. Available pilot and
full-scale operations data from plante employing the PhoStrip
process are presented in Table 1. The results of the findings
from the available pilot tests and plant-scale data are summar-
ized below;
The PhoStrip process is capable of producing ef-
fluent quality with total phosphorus (IP) of 1
mg/L, most of the time, without effluent filtra-
tion.
Excursion of total phosphorus above the 1 mg/L lev-
el can happen due to high suspended solids dis-
charged in the final clarifier effluent. Seven of
the plants shown in Table 1 include the use of ef-
fluent filters to assure that the effluent TP of 1
mg/L is met.
The PhoStrip process is applicable to a wide range
of activated sludge modes and various wastewater
characteristics.
The PhoStrip process requires less chemicals and
produces less sludge than conventional mainstream
treatment using lime addition for phosphorus re-
moval*
21
-------
TABLE 1. PHOSTKIP PROCESS PILOT AND FULL-SCALE PLANT OPERATIONS DATA
(O
NJ
Plant and location
District of Columbia
Seneca Falls, New York
Reno-Sparks, Nevada
Texas City, Texas
Brockton, Massachusetts
Union Carbide's Labora-
tory, Tonawanda, Hew York
Adrian, Michigan
Central Contra Costa
Sanitary District,
Walnut Creek, California
Design
flow
n>3/d
(mgd)
3,785
(1.0)
22,700
(6.0)
...
113,600
(30.0)
*-
---
18,900
(5.0)
26,500
(7.0)
Actual
flow
nVd
(mgd)
3,400
(0.90)
21,900
(5.8)
...
89,300
(23.6)
>-
---
___
-~
21,000
(5.6)
Influent
T-P Ortho-P
Status mg/lt mg/L
0.038 ra3/h (10 gph) 6.4
pilot test in 1972
Full-scale demonstra- 6,3
tion in 1973
Plant-scale test in 7,7
1974-1975
1.07 B3/h (4.7 8.4
gpra) , Phase 11
pilot-f»lant test in
1976
Started up in 1981j 6.3
mechanical problems
0.038 m3/h (10 gph) 7.9
pilot-plant test in
1976
1.04 m3/h (4,6 gpm) 8.7
pilot-plant test in
1976
Plant under construe-
tion
0.064 «3/h (0.28 12
gpm) pilot test in
1976
Started up in 1981j 4.5
temporary shutdown
after 5 months good
operation to replace
stripper feed pumps
0.45 m3/h (2 gpm) 10
pilot-plant operation
in 1981; Phase Id data
Effluent
T-P Ortho-P
mg/L mg/L References
0.92 0.45 41
0.55 12
liO 23, 24
0.8 24
0.75 25
0.7 24
1.0 - 26
* - 31
0.75 0.4 27
0.5* 13, 31
1.0 0.2 28
Effluent filters used.
-------
TABLE 1. (continued)
to
Plant and location
ftnthecst, New York
cacpentetsville, Illinois
Lansdale, Pennsylvania
Lititz, Pennsylvania
Little Patuxent, Maryland
(She Savage Plant)
Southdowns, New Xork
Texas City, fexas
Ithaca, New Jock
Ho Chester, New York
Tahoe/Truckee, Nevada
Design
flow
(rngd)
90,800
(24.0)
18,900
(5.0)
9,500
(2.5)
13,200
(3.5)
56,800
(15.0)
60,600
(16.0)
30,300
(8.0)
37,800
(10.0)
71,900
(19.0)
18,900
(5.0)
Actual
*i°w influent Effluent
mj/d r-p Ortho-p T-P Ortno-P
- * 31
_..
*E£fluent filters used.
-------
The PhoStrip process was marketed by Biosphericsf Inc. until
1974 when Union Carbide purchased the Levin patent. Biospherics
reacquired the PhoStrip rights in 1981, and is presently market-
ing the process at the following address:
Biospherics Incorporated
4928 Wyaconda Road
Rockville, Maryland 20852
Telephone: 301-770-7700
The equipment used in the PhoStrip process includes concrete
or steel tanks, mixers, pumps, and lime feed facilities. These
are all conventional wastewater treatment facilities and are
available from many competitive equipment suppliers. However,
there have been many cases of mechanical difficulties observed
during startup. There is need to provide a more reliable equip-
ment package, particularly those related to transfer pumps, lime
handling facilities, and automatic control instrumentation.
A/0 PROCESS
Since the &/O process was developed and patented by Air
Products and Chemicals, Inc. in the 1970's, a number of labora-
tory-scale and pilot-plant tests have been conducted, including
those at Bath, Pennsylvania? Washington, DC; Allentown, Pennsyl-
vania? Rochester, New York? and Largo, Florida. The only plant-
scale demonstration facility existing so far is the 3.0-mgd
retrofitted portion of the plant at Largo, Florida, After com-
pleting pilot and plant-scale A/0 studies, the City of Largo
decided to expand their entire 9-mgd plant to 15 mgd. Full-scale
A/O plants for several municipalities are currently in the de-
sign stage or under construction. Available data from pilot and
plant-scale operations employing the A/O process are presented
in Table 2. The results of findings from the pilot and plant-
scale tests are summarized as follows:
* Soluble ortho-phosphorus can be reduced to less
than 1 mg/L by the A/0 system without nitrifica-
tion in a relatively short detention time (less
than 4 hours).
9 Data from the Largo demonstration plant showed that
the A/O system with nitrification produced effluent
soluble phosphorus in excess of 1 mg/L during the
first four months, but less than 1 mg/L after that
period of acclimation. Ammonia nitrogen was gener-
ally reduced to less than 2 mg/L» which indicated
that nitrification was quite effective. However,
nitrate and nitrite levels in the treated
24
-------
, TABLE 2. A/0 PROCESS PILOT AND FULL-SCALE PLANT OPERATIONS DATA
Plant and location
Design Actual
flow flow
(mgd) (ngd)
Influent
Effluent
Status
T-P
mg/L
ortho-P
mg/L
T-P
mg/L
Qrtho-P
mg/L
References
Bath, Pennsylvania
Washington, DC
Allentown, Pennsylvania
Rochester, New tork
K5
tn
Largo, Florida
___ 11-21 liters <3-5.5 20.
gal) bench-scale
laboratory tests;
A/0 without nitrifi-
cation (2.6 hours de-
tention)
Pilot-plant data 3.4
Pilot-plant data; A/0 18,
without nitrification
(3.7 hours detention)
__'_ 2.8 m3 (750 gal) 2.23
pilot plant; A/0
without nitrifica-
tion (2.0 hours deten-
tion)
A/0 with nitrifies- 4.1
tion (4.0 hours deten-
tion)
___ 2.8 m3 (750 gal) 5.83
pilot plant; A/o
without nitrification
(2.1 hours detention)
11,400 12,100 Demonstration plant; 8.9
(3.0) (3.2) A/0 with nitrification
(4.2 hours detention)/
March 1980 perfo ma nee
test data
City operation; A/O - -
without nitrification;
February-June 1981 data
City operation; A/0
with nitrification;
July 1981 - February
1982 data
4.4 17
0.1 31
0.3 32
0.49 16, 17
0.3S 16, 17
1.03 17
1.85 0.51 17, 34, 35
1.3S 0.64 17
1.77 1.04 17
-------
TABLE: 2. (continued)
Plant and location
Largo, Florida (continued)
patapsco Plant,
Baltimore, Maryland
Lancaster, Pennsylvania
to
0%
Huron, Michigan
Spr ingettsbiary , Pennsyl-
vania
liberty Lake, Washington
Cox Creek, Maryland
Titusville, Florida
Design Actual
flow flow
n3/d n)3/d
(mgd) (mgd)
56,800
(15.0)
265,000
(70.0)
34,000
(9.0)
79,500
(21.0)
90,800
(24.0)
56,800
(15. D)
7,600
(2.0)
56,800
U5.0)
22,700
(6.0)
Influent Effluent
T-P Ottho-P T-P Ortho-P
Status mg/L mg/L mg/L mg/L References
Plant expansion under 17, 36
construction
Pilot-plant in prog 36
ress
Retrofit selected but -»-
not yet in design
Retrofit in design -~ - 36
Plant in design
Plant in design 36
Plant in design 36
Plant in design 36
Retrofit selected but 36
not yet in design
Selected but not yet - 3fr
in design
-------
effluent were in the range of 8 to 10 mg/L, which
indicated that only partial denitrification was at-
tained. The ability of the A/0 system to achieve a
high degree of denitrification and to produce ef-
fluent soluble phosphorus of less than 1 mg/L on a
consistent basis remains to be demonstrated.
The performance of the A/0 system is dependent on
the ratio of soluble BOD to phosphorus in the feed
to the system! it will operate*best when the ratio
is greater than approximately 10 to 1.
Phosphorus removal performance remained relatively
stable as operating temperature was decreased from
15°C to 10°C, and actually improved as operat-
ing temperature was further decreased from 10°C
to 5°C.
The A/Q system produces a pnosphorus-rich (4.2 to
6 percent by weight) excess sludge which must be
further stabilized before final disposal.
Concentrations of total phosphorus (i.e., soluble
plus suspended form) in the A/0 effluent at Largo
were in the range of 1.3 to 2.0 mg/L. The phos-
phorus concentrations were attributable to the
total suspended solids (TSS) in the clarifier ef-
fluent. (For example, if the TSS were 20 mg/L in
the clarifier effluent and contained 5 percent of
P, the phosphorus in these solids would amount to
1.0 mg/L), Therefore, effluent filters will be
necessary if effluent limitations call for total
phosphorus not to exceed 1 mg/L.
9 Chemical treatment may be required to reduce the
amounts of phosphorus contained in the internal
sidestreams, particularly in the case of superna-
tants from anaerobic digesters.
Additional information on A/0 can be obtained from the fol-
lowing address;
Environmental Products Department
Air Products and Chemicals, Inc.
Box 538
Alientown, Pennsylvania 18105
Telephone; 215-481-4911
27
-------
The equipment used in the A/Q process includes concrete or
steel tanksf mixersf aerators, clarifiers, and pumps for recycle
and sludge handling. As in the case of the PhoStrip process,
these are all conventional facilities available from many equip-
ment suppliers.
BARDENPHQ PROCESS
The original process developed by Barnard (14) in the early
1970's was a single-sludge, four-stage (anoxic-aeration-anoxic-
reaeration) system intended for nitrogen removal by biological
nitrification and denitrification. The modified Bardenpho proc-
ess is a five-stage system, with an anaerobic stage added ahead
of the original four-stage system for biological phosphorus re-
moval (see Figure 3). Over 30 wastewater treatment plants era-
ploying the Bardenpho process Cor both phosphorus and nitrogen
removal have been designed or operated in South Africa (44).
The first facility employing this process in the U.S. is the
5,300 m3/d (1.4 mgd) plant located in Palmetto, Florida. An-
other Bardenpho system, the 3,200 m3/d (0.85 mgd) plant in
Pluckemin, New Jersey, started operation in late 1982. The first
Bardenpho system in Canada is the 60,600 m3/d (6 mgd) facility
in Kelowna, British Columbia, which started operation in mid-
1982. Available pilot and full-scale operations data from plants
employing the Bardenpho process are presented in Table 3. The
results of findings from the pilot and plant-scale teats are
summarized as follows:
Bardenpho is a promising process for removal of
both phosphorus and nitrogen, although limited op-
erating data from the existing plants show incon-
sistencies in plant performance.
Many plants in South Africa produce variable con-
centrations of effluent phosphorus (see Table 3),
possibly due to a combination of reasons, such as
weak wastewater strength in the feed, high TKN-to-
carbon ratio, and low plant flow relative to de-
sign capacity.
The capability of the process to consistently pro-
duce total phosphorus of less than 2 rag/L, or
ortho-phosphate of less than 1 mg/L as P, remains
to be demonstrated. At Palmetto, Florida, the
average total phosphorus concentration during the
period between April and September 1980 was 2.2
mg/L after effluent filters. Addition of a small
dose of alum was necessary to reduce the total
phosphorus to 0.8 mg/L (1).
28
-------
TABLE 3. BARDENPHO PROCESS -- PILOT AND FULL-SCALE PLANT OPERATIONS DATA
Plant and location
Palmetto, Florida
Kelowna, B.C., Canada
pluckemin, New Jersey
Daspoort, Pretoria,
South Africa
Alexandra Plant,
Johannesburg, South
Africa
Olifantsvlei Plant,
Johannesburg, South
Africa
Johannesburg, South
Africa
Goukoppies, South Africa
Northern Works, South
Africa
Design Actual
m3/d m3/d
(mgd) (mgd)
5,300 4,600
(1.4) (1.22)
4,100
(1.08)
3,785
(1.00)
60,600
(6.0)
3,200
(0.85)
.__
---
__,
...
Influent
T-P ottho-P
Status nig/k mg/L
Design detention 8.2
=11.6 hours; started
up in October 1979;
February-April 1980
operating data
April-September 1980 6.2
operating data
October 1981-Maech 7.6
1982 operating data
(with minimal alum
dosage added)
Design retention
- 21 hours; started up
in July 1982? first 6
weeks of operating data
Started up in late
1982
4.1 m3/h (18 gpm) 10.5
pilot plant 10. ---
Full-scale plant 6.7
modifications operat-
ing data
Full-scale plant 4.2
modifications operat-
ing data
Laboratory-scale 9
plant No. 1
laboratory-scale 6.6
plant No. 1 (MLSS =
2,700 mg/L)
Laboratory-scale 6.6
plant No. 2 (MLSS »
3,100 mg/L>
Laboratory-scale 7.1
plant No. 1 (MLSS =
1,300 mg/L)
Effluent
T-P Ortho-P
mg/L mg/L References
2.5* - 37, 38, 39
2.2* --- 1
0.8* 1
0.2* 1
1
1,0** 15, 40
1.5 41
0.3** 15, 42, 43
2.2** IS, 42, 43
<1 41
1.7 41
1,1 41
6.4 41
*Ef£luent filters used.
**Not specified as either total or ortho-phosphorus.
-------
TABLE 3. (continued)
Plant and location
Northern Hocks, South
Me lea (continued)
Secunda, South Africa
Roodepoort, South Africa
Vanderbi jlpark, South
Africa
Meyer town, South Africa
Standerton, South Africa
Benoni, South Aft lea
Klerksdorp, South Africa
Stilfontein, South Africa
Baviannpoort , South
Africa
Northern Works, Johannes-
burg, South Africa
Design
flow
m3/a
<«jd)
« M H-"
3,400
(0.9)
6, BOO
(1.8)
9,100
(2.4)
4,900
(1.3)
4,500
(1.2)
7,600
(2.0)
7,900
(2.1}
10,600
(2.8)
15,900
(4.2)
151,400
(40.0)
Actual
flow
mVa
(-«»a>
!-«.
4,900
(1.3)
4,200
(l.l)
___
3,000
(0.8)
3,000
(0.8)
4,500
(1.2)
15,900
(4.2)
5,300
(1.4)
9,500
(2.5)
75,700
(20.0)
Influent Effluent
T-P Ortho-P T-P Ortho-P
Status mg/ti mg/t mg/L mg/t. References
Laboratory-scale 10. < 1 41
plant So. 2 (MLSS
2000 mg/L; primary
sludge added to
system)
Started up in October 3-10 1 1, 44
1976 (toxic and aero-
bic zones not physi-
cally separated)
Started up in March 13 9 1, 44
1978
Started up in October 2-7 2-7 1, 44
1979
Started up in April 9 --- 1-7 1, 44
1977
Started up in June 15 6-10 1, 44
1979
S tat ted up in August 10 7 1, 44
1979
Started up in Febru- 1** - 1, 44
ary 1979 (no secondary
anoxic stage)
Started up in March 1, 44
1977
Started up in August 15 11 1, 44, 45
1979 j poor phosphorus
removal due to high
TKN/carbon ratio
Design detention 9.4 7.1 6.0 1, 44, 46
» 14 hoursf started up
in Hovember 1979; low
strength of feed from
primary effluent caused
poor phosphorus removal
Effluent filters used.
**Not specified as either total or ortho-phosphorus.
-------
TABLE 3. (continued)
U>
Plant and location
Goudkoppies plant,
Johannesburg, South
Africa
RandEontain, South Africa
Indhoek, South Africa
Cape Flats, South Africa
Mitchell's Plain, South
Africa
Witbank, South Africa
Potchefstroom, South
Africa
Que Que, Zimbabwe
Umtall, Zimbabwe
, ,
E>9 jt I.SDIJ iry t SIIUDSOWG
Bulawayo, Zimbabwe
Design
flow
(mgd)
151,400
(40,0)
9, BOO
(2.6)
11,000
(2.9}
151,400
(40.0)
22,000
(5.8)
22,000
(5.8)
9,800
(2.6)
9,800
(2.6)
9,800
(2.6)
"} £ 'Sfin
J O r «3UU
(9.6)
9,800
(2.6)
Actual
flow Influent Effluent
n»3/d T-P Ortho-P T-E Ortho-P
(fflgd) Status mg/L mg/L mg/L mg/L
37,100 Primary sludge added 10 4.0 1.3 1.3
(9.8) to system during an
experimental period to
increase feed strength
and improve perform-
ance! experiment term-
inated to correct prob-
lems related to rag
98,400 Design detention 7.5 1.4 0.7
(26.0) = 14 hours; started
up in December 1977 j
1980-1981 operating
data
... ... ___ ... ___ ___
...
... ... __. ___
~ -
... ... ... ... ... .__
,
. ... ... , . .
_._ ... ... ... ... ...
...
... ... ... ... ...
..*,... ... ... ... ...
.
... ___ ... ___
.
** . .. .«w ... ...
-__
___ ___ ___ ___ ___
...
References
46
1, 44, 46
1
1
1
1
1
1
1
1
1
1
*Bffluent filters used.
**Kot specified as either total or ortho-phosphorus.
-------
At the Palmetto plant, the polishing filters remove
only 3 to 4 mg/L of suspended solids. The suspended
solids concentrations in the clarifier effluent
are very low (average of less than 5 mg/L) before
final filtration treatment, due to the very low
sludge volume index (SVI) and rapid sludge settling
characteristics. This plant maintains a solids res-
idence time (SRT) of approximately 20 days, which
is in the low range of 20 to 40 days typically
found in the Bardenpho process.
Problems encountered during the start-up period at
the Palmetto facility were related to the internal
recycle pumps. Without the internal recycle, efflu-
ent nitrate concentrations exceeded 8 to 10 mq/L,
which caused biological phosphorus removal to de-
crease markedly to less than 50 percent. This was
actually a mechanical problem rather than one re-
lated to the process itself. Once the recycle pumps
were operable, the effluent nitrate concentration
decreased and phosphorus removal improved.
The Bardenpho process is marketed in the United States by
Envirotech at the following address:
EIMCO Process Machinery Division
Envirotech Corporation
669 West Second South
P.O. Box 300
Salt Lake City, Utah 84110
Telephone: 801-526-2000
As in the case of the PhoStrip and A/0 processesf the equip-
ment used in the Bardenpho process includes the conventional fa-
cilities of concrete or steel tanks, mixers, aerators, clari-
fier s, and pumps.
-------
SECTION 4
COMPARISON WITH EQUIVALENT TECHNOLOGIES
EQUIVALENT CONVENTIONAL CONCEPT
Although the primary purpose of this evaluation is to com-
pare the costs for phosphorus removal, the PhoStrip, A/O, and
Bardenpho processes have different levels of applications with
respect to their capability to provide various degrees of BOD,
phosphorus, and nitrogen removal. Due to this complexity, these
three processes should not be compared with each other indis-
criminately- The conventionally-available phosphorus removal
methods primarily involve mineral addition with alum, ferric
chloride, or pickle liquor.
The total costs involved for using ferric chloride are
slightly less than those for alumj however, iron and color con-
centrations in plant effluents treated with ferric chloride or
pickle liquor may become a concern on occasion. The costs in-
volved in using two-stage tertiary lime treatment are usually
higher than those for alum treatment, except in the case of very
large plants (see Reference 66, Pact Sheets 4.2.2 vs 5.1.1).
Furthermore, lime treatment generates more solids handling, as
well as potential precipitation and line freezing problems. For
aXo. of the above considerations, the conventional activated
sludge treatment (one, two, or three separate-stage systems, de-
pending on the degree of nitrogen removal involved), together
with alum addition, is assumed as the baseline technology for
cost comparison with the three proprietary phosphorus removal
processes. The alternative cases evaluated for costs and energy
requirements in this technology assessment report are depicted
in Table 4. Tne alternative cases included here are considered
to be among those more frequently encountered, but are not meant
to be exhaustive.
It should be further noted that, in this model comparison,
it was assumed the PhoStrip process could produce effluent TP
of 1 rog/L, and that the A/O and Bardenpho processes could
produce effluent TP of 2 tng/L without effluent filters.
33
-------
TABLE 4, ALTERNATIVE CASES EVALUATED UNDER TECHNOLOGY ASSESSMENT
OF BIOLOGICAL PHOSPHORUS REMOVAL
Alternative cases
A B
(Baseline)
Activated sludge with alum addition
1-Stage 2-Stage 3-Stage PhoStrip
A/O Bardenpho
to
1, Phosphorus removal
(effluent TP = 1
mg/L)
2. Phosphorus removal
(effluent TP = 2
mg/L)
3. Phosphorus removal
and nitrification
(effluent TP = 2
mg/L, NH3-N = 1
mg/L)
4. Phosphorus removal
and nitrification/
denitrification
(effluent TP = 2
mg/L, TN = 3 mg/L)
1-A
2-A
3-A
4-A
1-B
2-B
1-C
2-C
3-C (*}
4-D
TP « Total phosphorus.
TN = Total nitrogen.
* = Partial denitrif ication to TN - 10 mg/L in A/0 process per Largo, Florida data.
-------
The related sludge handling processes assumed in the model
are as follows:
* Thickening of waste activated sludge by Dissolved
Air Flotation (DAF) for all plant sizes except
1,892 m3/d (0.5 mgd).
* Stabilization of primary and waste activated sludge
(except the latter from Bardenpho) by aerobic di-
gestion for plants smaller than 37,850 m3/d (10
mgd), or anaerobic digestion for plants greater
than 37,850 m3/d (10 ragd).
Dewatering of stabilized sludge by sludge drying
bed for plants smaller than 3,785 m3/d (1 mgd),
or vacuum filtration for plants greater than 3,785
mj/d (1 mgd).
Sludge hauling (32 kin (10 miles) one way) and
landfilling for all plant sizes.
COST COMPARISON
For each of the alternatives indicated in Table 4, costs
were developed for three plant sizes based on average design
flow:
1. 1,892 m3/d ( 0.5 mgd)
2. 18,925 mVd ( 5p0 mgd)
3. 189,250 m3/d (50.0 mgd)
In each case, costs were compared on a "total plant" basis
since the various processes would generate different amounts of
biological and inorganic solids, which affect sludge handling
and disposal costs.
The economic analysis of the three proprietary processes and
baseline technologies considered the initial investment cost
(capital cost), the annual operation and maintenance cost, and
the present worth cost of the total treatment system. Cost esti-
mates developed by the U.S. EPA for evaluating innovative and
alternative technologies (66) were used as the primary source
for estimating installed capital, and annual operation and main-
tenance costs for most of the unit processes involved. These
cost estimates were supplemented with cost figures from Appendix
H of the Areawide Assessment Procedures Manual (67) for the non-
structural cost components (e.g., influent pumping or lift sta-
tion, and miscellaneous structures such as control buildings,
outfall sewer, etc.). Cost curves for the A/O and Bardenpho
processes were not available in the literature; therefore, these
costs were developed by WESTON based on preliminary concept de-
sign of the facilities and in-house cost estimates.
35
-------
All cost estimates were updated to reflect October 1982
construction costs ( Eng ineeringNews_ Record Construction Cost
Index 3875). The basic assumptions and procedures utilized in
estimating construction costs are summarized in Appendix A.
The estimated capital, O&M, and total present worth costs
for each of the alternative cases and different plant sizes are
presented in Tables B-l through B-12 in Appendix B. Tables 5, 6,
1, and 8 show the summaries of cost comparison for equivalent
alternative cases. A summary of least cost alternatives (based
on total present worth) is presented in Table 9. The cost curves
for capital and total present worth costs for these alternatives
are depicted in Figures 5(a), 6{a), 7(a}f and 8(a). The cost
curves for comparative o&M costs are presented in Figures 5(b),
6(b), 7(b)f and 8(b).
It should be noted that site specific conditions will effect
changes in the relative costs of each of these alternative tech-
nologies and, therefore, these estimates are merely presented as
guidance to potential users to assist their cost-effective analyses
in terms of procedure and reasonable default values. Also, no
consideration has been given to retrofit applications, which
greatly accentuate the controlling nature of site specific con-
ditions.
ENERGY REQUIREMENTS
An approach similar to that utilized for cost comparison was
used for estimating the energy requirements for the alternative
cases shown in Table 4. The estimated energy requirements by
unit processes are presented in Tables B-13 through B-24 in Ap-
pendix B, and summarized in Table 10. Those alternatives requir-
ing the least amount of energy are also denoted in Table 10,
36
-------
w
j
TABLE 5. SUMMARY OF COST COMPARISON1
CASE 1
PHOSPHORUS REMOVAL
(EFFLUENT IP = 1 mg/L)
Plant size
Alternative
1-A
(Baseline)
1-B
1-C
Costs
Capital2, $
O&M, $/year
Total present worth,
Capital2, $
O&M, $/year
Total present worth,
Capital2, $
O&M, £/year
Total present worth,
1,892 m3/d
(0.5 mgd)
2,461,000
202,000
$ 4,501,000{*)
3,373,000
253,000
$ 5,928,000
2,990,000
210,000
$ 5,111,000
18,925 ni3/d
(5 mgd)
9,628,000
805,000
17,757,000(*)
11,182,000
690,000
18,150,000
11,763,000
775,000
19,589,000
189,250 m3/d
(50 mgd)
49,306,000
5,200,000
101,817,000
52,416,000
3,666,000
89,436,000(*)
56,319,000
4,212,000
98,853,000
Alternative 1-A * One-stage activated sludge system with alum addition
Alternative 1-B = PhoStrip,
Alternative 1-C * A/O (4 hours total detention) with effluent filters.
Tables B-lf B-2, and B-3 in Appendix B for breakdown of costs by unit
processes.
2ENR Construction Cost Index - 3875.
(*) Denotes least cost alternative.
-------
U)
00
TABLE 6, SUMMARY OF COST COMPARISON1
CASE 2
PHOSPHORUS REMOVAL
(EFFLUENT TP = 2 mg/L)
Plant size
Alternative
2-A
(Baseline)
2-B
2-C
Costs
Capital2, $
O&M, $/year
Total present worth,
Capital2, $
O&M, $/year
Total present worth,
Capital2, $
O&M, $/year
1,392 m3/d
(0.5 mgd)
2,451,000
197,000
$ 4,440,000
3,373,000
253,000
$ -5,928,000
2,496,000
183,000
18,925 m3/d
(5 mgd)
9,602,000
774,000
17,418,000
11,182,000
690,000
18,150,000
9,600,000
641,000
189,250 m3/d
(50 mgd)
49,113,000
4,890,000
98,494,000
52,416,000
3,666,000
89,436,000
. 46,419,000
3,540,000
Alternative 2-A = One-stage activated sludge system with alum addition.
Alternative 2-B = PhoStrip.
Alternative 2-C = A/0 (4 hours total detention) .
Tables B-4, B-5, and B-6 in Appendix B for breakdown of costs by unit
processes. J ""*'-
2ENR Construction Cost Index = 3875.
(*) Denotes least cost alternative.
-------
TABLE 7. SUMMARY OF COST COMPARISON1
CASE 3
PHOSPHORUS REMOVAL AND NITRIFICATION
(EFFLUENT TP = 2 mg/L, NH3~N = 1 mg/L)
U)
Plant size
Alternative
3 -A
(Baseline)
Costs
Capital2, $
O&M, £/year
Total present worth,
1,892 m3/d
(0.5 mgd)
2,990,000
227,000
$ 5,282,000
18,925 m3/d
(5 mgd)
11,376,000
854,000
20,000,000
189,250 m3/d
(50 mgd)
56,239,000
5,369,000
110,457,000
3-C
Capital2, $ 2,788,000
O&M, $/year 195,000
Total present worth, $ 4,757,OOQ(*;
10,596,000
702,000
17,685,000(*)
52,501,000
3,952,000
92,409,000(*}
Alternative 3-A = Two-stage activated sludge system with alum addition.
Alternative 3-C » A/0 (6 hours total detention) for nitrification and partial
denitrification to TN = 10 mg/L.
%ee Tables B-7, 8-8, and B-9 in Appendix B for breakdown of costs by unit
processes.
2ENR Construction Cost Index = 3875.
(*) Denotes least cost alternative.
-------
TABLE 8. SUMMARY OF COST COMPARISON*
CASE 4
PHOSPHORUS REMOVAL AND NITRIFICATIGN/DENITRIFICATION
(EFFLUENT TP = 2 mg/L, TN = 3 ITig/L)
Plant size
Alternative
4-A
(Baseline)
Costs
Capital2, $
O&M, 6/year
Total present worth,
1,892 m3/d
<0.5 ragd)
3,433rOQQ
274,000
$ 6,200,000
18,925 m3/d
(5 mgd)
12,913,000
1,112,000
24,142,000
189,250 m3/d
(50 ragd)
64,576,000
7,469,000
140,000,000
4-D
Capital2, $ 2,947,000 12,026,000 68,742,000
O&M, $/year 190,000 701,000 4,219,000
Total present worth, $ 4,866,000(*) 19,105,000(*} 111,347,000(*)
Alternative 4-A = Three-stage activated sludge system with alum addition.
Alternative 4-D = Bardenpho (16 hours total detention) .
Tables B-10, B-ll, and B-12 in Appendix B for breakdown of costs by unit
processes.
2EHR Construction Cost Index = 3875.
(*) Denotes least cost alternative.
-------
TABLE 9. SUMMARY OF LEAST COST ALTERNATIVES1
Alternative2
1-A (Baseline)
1-B (PhoStrip}
1-C (A/0)
2-A (Baseline)
2-B (PhoStrip}
2-C (A/0)
3-A (Baseline)
3-C (A/0)
4-A (Baseline)
4-D (Bardenpho)
1,892 m3/d
(0,5 ragd)
(*)
._.
*««
(*)
=
(*}
(*)
Plant size
18,925 m3/d
(5 mgd}
(*)
-__
{*)
_
(*)
.«*.
(*)
189,250 ra3/d
(50 mgd)
/*)
\ r
i- limn.
(*}
(*)
(*}
^Based on total .presecLtjQrtb costs. \
Table 4 for definition of alternative.
41
-------
TABLE 10. SUMMARY OF ENERGY REQUIREMENTS1 IN 10 3 KWH/YEAR
Plant size
Alternative2
1-A
1-B
1-C
2-A
2-B
2-C
3-A
3-C
4-A
4-D
(Baseline)
(PhoStrip)
(A/0)
(Baseline)
(PhoStrip)
(A/0)
(Baseline)
(A/0)
(Baseline)
(Bardenpho)
1,892 m3/d
(0.5 mgd)
309(*5
353
364
309(*)
353
332
393(*)
440
417
383(*)
18,925 m3/d
(5
3,
3,
3,
3,
3,
3,
3,
3,
4,
3,
mgd)
171
146(*5
353
171
146
028(*>
815
758(*j
035
832(*»
189,250 m
(50
21,
20,
23,
21,
20,
20,
27,
26,
30,
32,
Vd
mgd)
950
960
489
950
960
389
902
453
(*>
(*)
(*)
002(*)
125
Isee Tables B-13 through B-24 in Appendix B for breakdown of
energy requirements by unit processes.
%ee Table 4 for definition of alternatives.
42
-------
1000
900
aoo<
700
as
500'
TO'
300-
O MO.
§ w
I »
g
CL.
5 20-
§ ,-
3 9"
1 8-
O T.
t.o.
Legend
One-Stage Activaled Sludge with Alum Addition (Baseline)
PhoStrlp
. A/O witti Effluent Fitters
i. J.
1 1,11.
-1 L.
I I II.
J L
' i 1-1
0.1
3 .4 » 6 .7
05
3 * ' 6 7 t 9
5 W
' 60 708090
SO 100
LLI I 1 i 1 I f
i 1
t.008 1,892
Flow, mgd
I i i i i i i i
:D,OQO
Flow, roVd
1 1 II
r - " ' u
W.WI
1 1 1 1 1
109.000
rj -1 i
189258
Figure 5(a). Capital cost comparison.
Case 1: Phosphorus removal (effluent TP = 1 mg/l).
43
-------
«0
90-
60-
ITO-
eo-
50-
10-
9-
0.
a
&
I <-
O
O
5
? tt.
§ os-
c
< M-
OS-
OS-
M-
01-
LEGEND
One-Stage Activaterf Sludge wift Afum Addition (Baselinei
PhoStrip
MO with Effluent Filters
Annual
OSM
Costs
-I i1, I f ,1.1
J 1, .1
4 8 7 « »'
S 10
M 40 I a» 70S)SO
SO 100
p I I I 111
Flow, mgd
1I I-LI IJ
J 1 1 J 1,
I.CCO
tn.oco
Flow,
100 000
189550
Figure S(b). O&M cost comparison.
Case 1: Phosphorus removal (effluent TP = 1 mg/l).
44
-------
1005.
SO.
800-
TO-
HO.
500'
m-
a ' no-
's »'
a, »
E ro-
*
50'
«'
30-
©
1 "
o
13
O 10.
9-
m a*
o.
a ;:
5-
LEQEND
One-Stage Activated Sludge with Alum Addition (Baseline)
PhoStrip
A/O
Total
Present
Worth
Capital
Costs
J L
I I I.
-i 1 1,1111
J L
-7-83.
20 M «
Flow, tngd
100
II I tlllt
T"
im
i i i i i i 11
.1 l l t i,,.
1,000
mow
Flow, m»
r*_
U.M5
1WCOO
r
189250
Figure 6(a). Capital cost comparison.
Case 2: Phosphorus removal (effluent TP 2 mg/l).
45
-------
100-
90,
" 70-
50.
40'
30-
29-
C5 *u"
f 9'
C 8'
£ T'
£ 6-
a
5 3-
o
«8
O
3 to.
g 09.
< OB-
07-
04.
03-
LEGEND
One-Stage Activated Sludge with Alum Addition (Baseline)
, PhoStrlp
Annual
O&M
Costs
' r i
J_
_i L
I '
.1 1 1,1
It«. I I »
A o^'7JJ«
2 3
Flow, mgd
1 i I I I I I
» 30
'ill
1 60 78»Sa]
50 100
I.OCO
VMS
IOO.OCO
Flow, rnVd
Figure 6(b). O&M cost comparison.
Case 2: Phosphorus removal (effluent TP 2 mg/l).
46
-------
tow
900
$00
TOO
MO
SOB
400
300
200
too
m
c «
§
£ »
a.
3
o
o
a
"5
«
c
o
o
1
o
o
3
a
3
20 -
LEGEND
Two-Stage Activated Sludge with Alum Addition (Baseline)
A/O
' ..f I I I Il_
2 a * 1 ft ? e o
Ji L
I... Ill,
8789"
I 111.
30 « 60 708095
M 100
U_J_
1 1 1 1 1 .
JJTO
,1 L
tm
Flow, mgd
1 'Mil1
10,030
Ffow, m3/t}
I
P
18,925
1 1 1 1 1 II 1
101000
r1
189250
Figure 7(a). Capital cost comparison.
Case 3: Phosphorus removal (effluent TP = 2 mg/1, NHs-N = 1 mg/1).
47
-------
IOC.
90.
80.
10.
W.
40'
30'
20-
cs
> 10-
& 9>
flL 8-
« ?-
~ 6!
o
a s<
"5
in <
c
_o
= 3-
O 2-
O
MS
O
"S
2 If.
E OJ.
< OB-
07-
06-
05-
01-
01-
LEGEND
Two-Stage AcMvaled Sludge with Alum Addition (Baseline)
A/O
Annual
O&M
Costs
| ~ - i
_L
-l_
J L
0.1
3 4 "" 6 7 8 9 '
5 JO
1 GO 708GW
50 100
11 ' I I I I
Flow, mgd
I » '«'! ,1
I ' l » i 1 i i
1,000
1.192
10,000
Flow, m'/d
"T
1US2S
100,O)0
Figure 7(b). O&M cost comparison.
Case 3: Phosphorus removal (effluent TP = 2 mg/1, NH3-N = 1 mg/l).
48
-------
1000
900
BOO
TOO
600
500
400-
300-
S 200
a
B
o ' ion.
= 90'
1
o
I
o
o
1
a
(0
1 «-
20-
10.
s-
8-
I.
6'
5-
3-
LEGEND
Three-Stage Activated Sludge with Alum Addition (Baseline)
Bardenpho
-I ' ' ' ' '
.3 .4 ' 6 J S 3 *
-I 1 1 , I I 1 1
M'
10
I 4 ' 6 7 J 9 '
5 it
Flow, mgd
20 30
i ' i '
m n 80 90
» 100
1.000
1J89Z
WOW 18
Flow. m5/d
1DO.OOO
Figure 8(a). Capital cost comparison.
Case 4: Phosphorus removal, nitrification and denitrification
(effluent TP - 2 mg/l, TN = 3 mg/i).
49
-------
100-
90-
80.
70-
60.
50-
30-
20-
a »
o 9.
* !'
a. 7.
e 5-
I
£ 3-
5
a
o
O
U
-OJ»
04-
07-
05-
OS-
03-
92-
0,1-
LE6END
Three-Stage Activated Sludge with Alum Addition (Baseline)
Barcfenpho
Annual
OSM
Costs
' ' I ' J '
I I I 11...
t '6789'
5 !0
1 I
J, I.J.
Flow, fngd
M 40 ' 60 706090
SO 100
J 1L..J 1.1 1,1
I I I I M I
JL
-M
1MO
10.000
\t$R
100.000
169560
Fiow. I
Figure 8(b). O&M cost
Case 4: Phosphorus removal, nitrification and denitrification
(effluent TP = 2 mg/l, TN «= 3 mg/l).
50
-------
SECTION 5
ASSESSMENT OP NATIONAL IMPACT
MARKET POTENTIAL
The needs for phosphorus and nitrogen removal in the United
States have been projected by the U.S. EPA in the "1980 Needs
Survey for Conveyance and Treatment of Municipal Wastewater11
(68) under Category IIB - Advanced Wastewater Treatment (AWT).
The requirement for AWT generally exists where water quality
standards require removal of such pollutants as phosphorus,
ammoniaf nitrate, and other substances. In addition, this AWT
requirement exists where removal for conventional pollutants
(BOD, solids) exceeds the Advanced Secondary Treatment (AST)
level, i.e., 95 percent or 10/10 mg/L. It should be noted that a
large number of plants designed for Advanced Secondary Treatment
(AST) also have the capability for removing phosphorus and am-
monia nitroqen.
Table 11 summarizes the projected facilities designed to
provide advanced wastewater treatment (broken down into phos-
phorus, ammonia nitrogen, and total nitrogen removal) in the
U.S. for the years 1980 and 2000.
It can be seen that the total wastewater flov; of facilities
requiring AWT is projected to increase five-fold from 2,840,000
m3/d (750 mgd) in the year 1982 to 15,500,000 m3/d (4,100
mgd) in the year 2000. Close to 60 percent of the total flow for
AWT would involve phosphorus removal, while removal of ammonia
nitrogen and total nitrogen would amount to 75 percent and 25
percent, respectively, of total AWT flow by the year 2000. The
number of plants designed for phosphorus removal under AWT is
projected to increase from 85 in the year 1980, to 263 in the
year 2000. The number of plants designed for ammonia nitrogen
removal under AWT is expected to increase from 116 in the year
1980, to 493 in the year 2000, while the corresponding number of
plants for total nitrogen removal is 35 and 118. The sizes of
these AWT plants range from less than 378 m3/d (0.1 mgd) up to
189,250 m3/d (50 mgd), with the average size being near 19,000
m3/d (5 mgd) in 1980, and 30,000 m3/d (8 mgd) in 2000.
Therefore, the trend is toward building more large-size AWT
plants between 1980 and 2000 than those that currently exist.
From the data presented in Table 11, it appears that significant
51
-------
TABLE X.I. FACILITIES DESIGNED TO PROVIDE ADVANCED WASTEWATBR TREATMENT (AWT) FOR ALL STATES AND U.S. TERRITORIES*'2
Facilities in
operation in 1980
Facilities to be
in operation in
2000
Increment from
1980 to 2000
Average plant
size in 1980
Average plant
size in 2000
Total
flow
1,000 mVd
% of
total
flow
48.8
75.1
80.9
~ -
_.»-.
Number
of.
plants
35
118
83
-»_
.~
Total N
Flow
1,000 m3/d
(ragd)
574
(152)
3,888
(1,027)
3,314
(875)
16.4
(4.3)
33.0
(8.7)
8 of
total
flow
20.1
24.8
25.9
Reference 68, the "1980 Needs Survey."
2Does not include Advanced Secondary Treatment (AST) plants, which are for removal of BOD/TSS to the range of 10/10 to
24/24 mg/I», but also provide specific processes that remove phosphorus and/or ammonia in excess of the amounts normally
removed by secondary treatment.
-------
market potential exists for all three proprietary processes.
Specifically, the greatest market potential exists in the fol
lowing areas:
* Application of the PhoStrip process for phosphorus
residual of 1 mg/L; for plant size above 19,000
m3/d (5 mgd).
Application of the A/0 process for phosphorus te-
sidual of 2 mg/L; for all plant sizes.
* Application of the A/O process for phosphorus and
ammonia nitrogen residuals of 1 and 2 mg/L, re-
spectively; for all plant sizes.
* Application of the Bardenpho process for phosphorus
and total nitrogen residuals of 2 and 3 mg/L, re-
spectively,- for all plant sizes.
COSTS AND ENERGY IMPACTS
The national dollar needs for upgrading/enlarging existing
treatment plants and for construction of new advanced wastewater
treatment (AWT) facilities are presented in Table 12 based on
the "1980 Needs Survey" (68). The total incremental costs of AWT
above the advanced secondary treatment (AST) level are estimated
at $830 million in 1980 dollars. It is noted that these costs
are for construction only and do not include costs for operation
and maintenance. From comparison of total present worth costs
presented in Tables 5 through 8, it can be seen that significant
cost savings can be realized when either the PhoStrip, A/0, or
Bardenpho process is used instead of the conventional (Baseline)
process. The potential cost savings tends to increase when the
plant size is increased. For plant size in the range of 18,925
to 189,250 m3/d (5 to 50 mgd), savings in total present worth
costs are estimated to be in the range of 10 to 25 percent on a
total plant basis, depending on effluent requirements and the
type of alternative process used. Savings in energy are expected
to be less significant than in total present worth costs. As can
be seen from Table 10, energy savings through the use of the
three proprietary processes are generally less than 10 percent
on a total plant basis, but can be as high as 20 percent, da-
pending on the plant size, effluent requirements, and the type
of alternative process used.
53
-------
TABLE 12. NATIONAL DOLLAR NEEDS FOR CHANGES IN EXISTING
TREATMENT PLANTS AND FOR CONSTRUCTION OP NEW
ADVANCED WASTEWATER TREATMENT (AWT) FACILITIES1
Type
Number
of
plants
Total
dollar
needs2,
in mil-
lions
of 1980
dollars
Changes in existing plants
Planned changes by present design 251 335.6
level of tertiary treatment for all
facilities in operation in 1980
Plants to be upgraded to tertiary
treatment
Plants to be enlarged and upgraded to
tertiary treatment
Sub-total
New tertiary treatment facilities
Total 461 829.2
16
11
278
183
10.3
49.7
395.6
433.6
Reference 68, the "1980 Needs Survey."
2Incremental costs above advanced secondary treatment (AST).
54
-------
RISK ASSESSMENT
All three proprietary biological phosphorus removal process-
es have been reasonably well developed. Generally, they are cap-
able of providing 1 to 2 mg/L of residual phosphorus. Therefore,
the risk involved in using any of these processes is not in its
complete failure/ but in its capability to meet a specific set
of effluent limitations. From available data presented in Tables
If 2, and 3, it can be seen that these processes can be margin-
al, at times, in meeting the total phosphorus concentrations of
1 mg/L or 2 mg/L. Conducting pilot tests to obtain data for ap-
plication in a specific case, prior to design, can minimize such
risk.
Provision of additional facilities, such as the use of ef-
fluent filters and supplemental mineral addition, will further
reduce the risk of not meeting the effluent requirements. Howev-
er, such a provision would also reduce the benefit of cost sav-
ings that can be gained from the use of these alternative proc-
esses.
55
-------
SECTION 6
RECOMMENDATIONS
FURTHER RESEARCH AND DEVELOPMENT EFFORTS
All three proprietary processes for biological phosphorus
removal are based on the basic mechanism that utilizes the an-
aerobic treatment to pre-condition the microorganisms for subse-
quent enhanced uptake of phosphorus under aerobic conditions.
Although significant data and experience have been obtained to
substantiate the validity of the fundamental concept, numerous
complex factors affecting the performance of the three different
versions of biological phosphorus removal systems are not yet
fully understood. Many researchers have raised a number of un-
answered questions and expressed needs for further research and
development, which have been put together in a perspective by
Irvine, Stensel, and Alleman (1). Some of the more important as-
pects of research needs, including those identified by numerous
researchers, as well as the opinions of the consultant, are
listed in the following:
Basic studies involving organisms selection, phy-
siological states, survival, and the direct impact
of the anaerobic zone must be conducted before bi-
ological phosphorus removal can be understood ful-
ly.
Current design of the anaerobic section in each of
the three proprietary processes appears to be em-
pirical, and there is a lack of rational basis for
sizing the anaerobic stage. The A/O system employs
a relatively short detention time in the anaerobic
zone and requires a sufficiently high input of sol-
uble substrate to ensure rapid formation of anaero-
bic conditions. The Bardenpho system has a slightly
longer detention time, but, as in the case of A/O,
it also requires the presence of soluble substrate
to establish adequate anaerobic conditions. (Some
of the failures associated with the Bardenpho sys-
tem have been related to low COD:TKN ratios in the
feed to the system.) On the other hand, the
PhoStrip process employs a relatively long SRT in
the anaerobic stripper, which allows for hydrolysis
56
-------
of participate organics contained in the portion of
recycle sludge subjected to anaerobic treatment.
Furthermore, introduction of dissolved oxygen and
nitrate into the anaerobic zone has been found to
interfere with biological phosphorus release in all
three proprietary processes. The quantitative ef-
fects of these various factors on the sizing of the
anaerobic tank need to be further delineated.
* The three biological phosphorus removal processes
are capable of producing effluent total phosphorus
of less than 2 mg/L; however, effluent total phos-
phorus concentrations of 1 to 2 mg/L appear in the
marginal area that can hardly be predicted with
certainty. The total phosphorus consists of soluble
phosphorus as well as phosphorus associated with
t-.he suspended solids form. The soluble phosphorus
in the effluent is related to the performance of
the process employed, while the phosphorus in the
solids form is related to the settling characteris-
tics of sludge maintained in the system. Further
research is necessary to develop a better basis for
predicting effluent quality under various operating
conditions and wastewater characteristics.
PROCESS/TECHNOLOGY MODIFICATIONS
All three processes discussed in this document have been well
developed from the phosphorus removal standpoint. Potential im-
provements or modifications for each of the three processes are
as EO1J.OWE:
* The Phostrip process has been applied in conjunc-
tion with a two-stage activated sludge system to
provide phosphorus and ammonia nitrogen removal
Nevertheless, the basis of design for necessary"
modifications in the PhoStrip process to integrate
with biological nitrification/denitrification
treatment systems needs to be further developed,
Some modifications in the A/O process, possibly in
the area of internal sludge recycle and^more appro-
priate sizing of the anaerobic/anoxic/aerobic
stages, may be necessary to demonstrate the capa-
bility of this process to achieve more satisfactor,
phosphorus removal and a higher degree of nitrifi-"
cation/denitrification than currently available.
57
-------
Some modifications in the Bardenpho process may be
necessary to achieve more satisfactory performance
in phosphorus and total nitrogen removal, particu-
larly under the conditions of low CODrTKN ratio in
the feed to the system.
-------
REFERENCES
1. Irvine, R.L., H.D. Stensel, and J.E. Allanman. Summary Re-
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Wastewater Treatment, Annapolis, Maryland, June 22-24,
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2. U.S. EPA. Process Design Manual for Phosphorus Removal. EPA-
625/1-76-OQla, 1976.
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-------
10. Garber, W.F. Phosphorus Removal by Chemical and Biological
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-------
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-------
31. Levin, G.V., Biospherics, Inc., undated.
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-------
43-
44-
Aspects °£
nt
fecence Seminar on Wraanhati 2! P"
Processes, international AssociatI n
«arch, Pretoria, South Africa' 198?.
on wat
phosphate Re-
t the Post Con-
"°lo9lcal Treatment
""" Pollution "<=-
Johannesburg Present^ !t th»
Phosphate Reiioval I
national ftSuJi on
South Africa, 1982.
-*- Nlcholls-
? «f"°val Plants in
Conference Seminar on
, ProcesseB' I"ter-
Research, Pretoria,
Research Laboratory
use, Tahoe city,
Engineering
30:776, 1966.
in Biology, Btrue-
Bacteriology Reviews,
54th Annual
Michigan, 1981.
onto «n Presented « the
control Conference, Detroit,
50
ed Enhanced Phosphoemva
-------
53. Nicholls, H.A., and D.W. Osborn. Bacterial Stress: Prereq-
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Acinetobactor Spp_. Microbiology Letters, Federation of Mi-
crobiological Societies, 273-279, 1980,
56. Senior, P.J., et al. The Role of Oxygen Limitation in the
Formation of Poly B Hydroxybutyrate during Batch and Contin-
uous Culture of Azotobacter beijerincku. Biochemistry J.,
128: 1193, 1972.
57. Hong, S.N., et al. A Biological Wastewater Treatment for Nu-
trient Removal. Presented at the 54th Annual water Pollution
Control Federation, Detroit, Michigan, 1981,
58. Rensank, J.H., H.J.G.S. Donker, and H.P. deVries. Biological
P-Removal in Domestic Wastewater by the Activated Sludge
Process. Presented at the 5th European Sewage and Refuse
Symposium, Munchen, Procs. 487-502, 1981,
59, Gaudy, A., and E. Gaudy, Microbiology for Environmental Sci-
entists and Engineers. McGraw-Hill Book Co., 1980.
60. Marais, G.V.R., R.E. Loewenthal, and I. Siebritz. Review:
Observations Supporting Phosphate Removal by Biological Ex-
cess uptake. Selected Papers on Activated Sludge Process Re-
search at the University of Capetown, South Africa, 1981.
61. Funs, G.W., and M, Chen, Microbial Basis of Phosphate Remov-
al in the Activated Sludge Process for the Treatment of
Wastewater. Microb. Ecol. 2:119-138, 1975.
62. Brodish, K.E.O., and S.J. Joyner. The Role of Microorganisms
Other Than Acinetobactor in Biological Phosphorus Removal in
Activated Sludge Processes. Presented at Post Conference
Seminar on Phosphate Removal in Biological Treatment Proc-
esses, International Association on Water Pollution Re-
search, Pretoria, South Africa, 1982.
63. Osborn, D.W., and H.A. Nicholls, Optimization of the Acti-
vated Sludge Process for the Biological Removal of Phosphor-
us. Presented at the International Conference on Advanced
Treatment and Reclamation of Wastewater, Johannesburg, South
Africa, 1977.
64
-------
64. Stensel H.D. Biological Nitrogen Removal System Design,
American Institute of Chemical Engineers, Water, Vol. 70,
Number 209, 1980.
65. Knowles, G., et al. Determination of Kinetic Constants for
Nitrifying Bacteria in Mixed Culture with the Aid of an
Electronic Computer, Gen. Microbiology J., 38:263, 1965.
66. U.S. EPA. Innovative and Alternative Technology Assessment
Manual. MCD-53, EPA-430/9-78-009, 1980.
67. U.S. EPA. £reawide Assessment Procedures Manual. Vol. Ill,
EPA-600/9-76-014, 1976.
68. U.S. EPA. The 1980 Needs Survey, Conveyance, Treatment, and
Control of Municipal Wastewater, Combined Sewer Overflows,
and Stormwater Runoff, Summaries of Technical Data. EPA-43Q/
9-81-008, FED 23, 1981.
65
-------
APPENDIX A
COST AND ENERGY ANALYSIS ASSUMPTIONS
In order to compare the various alternatives, a basis for
the cost comparison was required. The major sources of costs
(capital, and operations and maintenance) and energy requirement
data were the Innovative and Alternative (ISA) Technology As-
sessment Manual (66), with additional input from the Areawide
Assessment Procedures Manual, Appendix H (67). Costs for the A/0
and Bardenpho processes were developed based on preliminary con-
cept design and WESTON's in-house cost estimates.
In order to accommodate the specific design conditions, num-
erous assumptions were required to adjust and extrapolate cost
data that will reflect the specific design case. The assumptions
utilized for technology evaluation are as follows:
Construction costs were updated to October 1982 ut-
ilizing the Engineering Mews Record (ENR) Construc-
tion Cost Index of 3875.
Operation and maintenance costs were updated to Oc-
tober 1982 utilizing EPA's Escalation Index of
3.55 and electrical energy cost of $O.Q5/kwh.
Construction costs were upgraded to capital costs
by inclusion of noncomponent costs. The noncompo-
nent costs and the percentage of construction costs
used are as follows:
Item Percent
Piping 10
Electrical 8
Instrumentation 5
Site Preparation 5
Engineering services and contingency costs were
each assumed to be 15 percent of the capital cost.
The sum of the construction costs, noncomponent
costs, engineering services, and contingency yield-
ed the total installed capital cost.
66
-------
For present worth analysis, all equipment was as-
sumed to have a 20-year service life (zero salvage
or replacement cost over cost-effectiveness time
period), and present worth was equal to the sum of
capital cost plus present worth of annual O&M
costs. A discount rate of 7-5/8 percent, which was
effective as of October 1982, was assumed. Present
worth factor = 10.0983.
For each of the alternative cases shown in Table 4,
costs were developed for the following three plant
sizes:
1,892 m3/d ( 0.5 ragd)
18,925 m3/d ( 5.0 mgd)
189,250 ra3/d (50.0 mgd}
Influent wastewater characteristics were assumed as
follows:
BOD5 =210 mg/L
TSS = 230 mg/L
VSS = 172 mg/L
TP =10 mg/L
TKN = 35 mg/L
NH3N = 20 mg/L
Preliminary treatment (including bar screens and
grit chambers) and primary clarifiers were assumed
to precede the biological treatment. The primary
clarifiers were assumed to provide 60 percent TSS,
35 percent BOD, 10 percent TP, and 14 percent TKN
removal.
The baseline technology for BOD, TSS, and phosphor-
us removal was assumed to be conventional activated
sludge with alum addition. This baseline technology
was compared with the PhoStrip and A/O processes.
To produce effluent TP of 1 mg/L, additional efflu-
ent filters were assumed to be required for the
A/O process in Case 1-.
The baseline technology for BOD, TSS, phosphorus,
and ammonia nitrogen removal was assumed to be high
rate activated sludge followed by nitrification ac-
tivated sludge with separate clarifiers in each of
the two stages. This baseline technology was com-
pared with the A/0 process.
-------
* The baseline technology for BOB, TSS, phosphorus,
and total nitrogen removal was assumed to be high
rate activated sludge, followed by nitrification
activated sludge, and by denitrification activated
sludge with separate clarifiers in each of the
three stages. This baseline technology was compared
with the Bardenpho process. In both cases, effluent
filtration would be required to achieve a TN resid-
ual of 3 rag/Lr but since the cost would be the same
for bothi filtration was not included in the com-
parison.
The design conditions for the PhoStrip process were
assumed to be the same as those indicated in Pact
Sheet 2.1.17 of the I&A Manual (66).
The A/0 process design detention times were assumed
to be as follows:
Detention time, hours
TP TP & NHj-N
Stage removal removal
Anaerobic (3-stage) 1.0 1.0
Anoxic {3-stage) 1.0
Oxic (aerobic, 4-stage) 3.0 ^._0
Total 4.0 6.0
MLSS = 2,000 mg/L
Internal flow recycle from oxic to anoxic stage
- 200 percent (for A/0 with nitrification)
To minimize the return of phosphorus contained in
the sidestreams of the A/O Process, an additional
lime dosage of 7.9 kg/1,000 m3 (gg Ibs/million
gallons) was assumed for aerobieally-digested
sludge, ?.nd 30 kg/1,000 m3 (250 Ibs/million
gallons) was assumed for anaerobically-digested
sludge.
68
-------
The Bardenpho process design detention times were
assumed to be as follows;
Stage Detention time, hours
Anaerobic 1.5
First anoxic 4.0
Aeration (nitrification) 6.5
Second anoxic 3.0
Reaeration 1 _. 0
Total 16.0
MLSS = 3,500 mg/L
Internal flow recycle from the aeration to first
anoxic stage - 400 percent
The excess biological sludge from the Bardenpho
process was assumed to require no further digestion
since the solids residence time (SRT) in the system
was estimated at 27 days under design conditions.
The anaerobic and anoxic tanks in the A/Q or
Bardenpho processes are to be covered.
Surface mechanical aerators were assumed to be used
in the aerobic stages. Maximum aerator capacity of
1.5 times the daily average requirement was pro-
vided. Mixing power of 10 kw/1,000 m^ (50 hp/mil-
lion gallons) tank capacity was assumed in all an-
aerobic and anoxic stages.
For the Bardenpho process and A/O with nitrifica-
tion and partial denitrification, the amount o£ ox-
ygen required is estimated to be reduced by 2.8
times the amount of nitrate nitrogen (HH3-N) de-
nitrified.
The primary sludge was assumed to have a solids
concentration of 4 percent from the clarifier un-
derflow. The waste activated sludge was assumed to
have a solids concentration of 0.8 percent (except
1.5 percent in the case of A/0) from the clarifier
underflow. The waste activated sludge was to be
further thickened to a minimum of 4 percent by dis-
solved air flotation (DAF) prior to combining with
the primary sludge for digestion, except at 1,892
in3/d (0.5 mgd).
69
-------
§SSiJ?nSefS!£Ss;ii:;
beds »as asaumed for
taring via vacuun'iT"" Plant' and dewa-
unitary landfill pproprKL Disposed of ia
sludge qeneration rates for var?SSUmPti°nS as to
sumed to allow for Sinn ya^ous cases were as-
in the I&A Manual. raolfied from data presented
70
-------
APPENDIX B
COST COMPARISON AND ENERGY ANALYSIS
Tables B-i through B-12 deal with cost comparison of the
various facility sizes; Tables B-13 through B-24 present an en-
ergy analysis for the same facilities.
71
-------
TABLE B-l. COST COMPARISON -- 1,892 ro3/d (0.5 ragd) FACILITY1
CASE 1
PHOSPHORUS REMOVAL (EFFLUENT TP = 1 mg/L)
ENR INDEX = 3875
Process unit
Alternative
1-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative
1-B
PhoStrip
Alternative
1-C
A/O
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Den itrificat ion/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAP)
Digestion (Aerobic)
Dewatering (Drying Bed)
Sludge Hauling/Landf illing
Sub-Total
Noncomponent Costs2
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL CGtiTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 188,000
47,000
122,000
447,000
31rOOO
63,000
96,000
78,000
125,000
78,000
204,000
$1,479,000
414,000
284,000
284,000
$2,461,000
$ 202,000
$4,501,000
$ 188,000
47,000
122,000
447,000
595,000
63,000
96,000
78,000
125,000
66,000
200,000
$2,027,000
568,000
389,000
389,000
$3,373,000
$ 253,000
$5,928,000
$ 188,000
47,000
122,000
501,000
-__
5,000
_ _ _
<
63,000
297,003
96,000
78,000
___
130,000
66,000
204,000
$1,797,000
503,000
345,000
345,000
$2,990,000
$ 210,000
$5,111,000
Appendix A for details of assumptions used in the cost analysis.
^Noncomponent costs include piping, electrical, instrumentation, and site
preparation.
3present worth computed assuming 20-year life at 7-5/8 percent interest
rate (PWF = 10.0983).
72
-------
TABLE B-2. COST COMPARISON 18,925 m3/d (5.0 mgd) FACILITY1
CASE 1
PHOSPHORUS REMOVAL (EFFLUENT TP = 1 mg/L)
ENR INDEX = 3875
Process unit
Alternative
1-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative
1-B
PhoStrip
Alternative
1-C
A/O
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Deni tr if icat ion/ Clarification
Ch lor i nation
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landf illing
Sub-Total
^loncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 705,000
196,000
438,000
2,035,000
_
78,000
_
-
191,000
310,000
250,000
204,000
470,000
658,000
251,000
$ 5,786,000
1,620,000
1,111,000
1,111,000
$ 9,628,000
$ 805,000
$17,757,000
$ 705,000
196,000
438,000
2,035,000
1,096,000
_
. .
_
191,000
___
310,000
250,000
188,000
470,000
595,000
246,000
$ 6,720,000
1,882,000
1,290,000
1,290,000
$11,182,000
$ 690,000
$18,150,000
$ 705,000
196,000
438,000
2,129,000
12,000
_ .*. _
_ _ _
191,000
1,300,000
310,000
250,000
196,000
500,000
595,000
247,000
$ 7,069,000
1,979,000
1,357,000
1,357,000
$11,763,000
$ 775,000
$19,589,000
LSee Appendix A for details of assumptions used in the cost analysis.
-Noncomponent costs include piping, electrical, instrumentation, and site
preparation.
^Present worth computed assuming 20-year life at 7-5/8 percent interest
rate (PWF = 10.0983).
-------
TABLE B-3. COST COMPARISON -- 189,250 lR3/d (50.0 mgd) FACILITY1
CASE 1
PHOSPHORUS REMOVAL (EFFLUENT TP = I mg/L)
ENR INDEX = 3875
Alternative
1-A
one-stage
activated
sludge
with alum
addition
(baseline)
Process unit
Alternative
1-B
PhoStrip
Alternative
1-C
A/o
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Deni tr if icat ion/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landf illing
Sub-Total
Noncomponent Costs2
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 3,
2,
12,
1,
1,
2,
2,
$ 29,
&,
5,
5,
$ 49,
$ 5,
$101,
600
783
270
995
-
579
_
_
798
-
190
000
391
740
818
467
631
297
689
689
306
200
817
i
i
t
i
-
i
-
-
f
-
r
i
i
t
r
f
r
r
f
i
r
r
r
000
000
000
000
-
000
_
_
000
-
000
000
000
000
000
000
000
000
000
000
000
000
000
$ 3,
2,
12,
2,
1,
1,
2,
2,
$31,
8,
6,
6,
$52,
$ 3,
$89,
600
783
270
995
740
_
-
_
798
-
190
000
344
740
583
457
500
820
048
048
416
666
436
i
r
i
r
r
-
-
-
r
-
I
r
t
r
f
r
/
i
r
r
f
f
i
000
ooo
000
000
000
-
-
-
000
-
000
000
000
000
000
000
000
000
000
000
000
000
000
$ 3,
2,
11,
5,
1,
1,
2,
2,
$33,
9f
6,
6,
$56,
$ 4,
$98,
600,
783,
270,
797,
230,
798,
950,
190,
000,
360,
818,
583,
467,
846,
477,
498,
498,
319,
212,
853,
000
000
000
000
-
000
-
-
000
000
000
000
000
000
000
000
000
000
000
000
000
000
000
%ee Appendix A for details of assumptions used in the cost analysis.
^Noncomponent costs include piping, electrical, instrumentation, and site
preparation.
^present worth computed assuming 20-year life at 7-5/8 percent interest
rate (PWF = 10.0983) .
74
-------
TABLE B-4. COST COMPARISON 1,892 m3/d (0.5 mgd) FACILITY1
CASE 2
PHOSPHORUS REMOVAL (EFFLUENT TP = 2 mg/L)
ENR INDEX =3875
Alternative
2-A
one-stage
activated
sludge
with alum
addition
(baseline)
Process unit
Alternative
2-B
PhoStrip
Alternative
2-C
A/0
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Deni tr if icat ion/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aercb'u)
Dewatering (Drying Bed)
Sludge Hauling/Landf illing
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supe1 vision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 188,000
47,000
122,000
447,000
25,000
63,000
96,000
78,000
125,000
78,000
204,000
$1,473,000
412,000
283,000
283,000
$2,451,000
$ 197,000
$4,440,000
$ 188,000
47,000
122,000
447,000
595,000
___
63,000
96,000
78,000
125,000
66,000
200,000
$2,027,000
568,000
389,000
389,000
$3,373,000
$ 253,000
$5,r^,ooo
$ 188,000
47,000
122,000
501,000
5,000
___
63,000
-_-
96,000
78,000
130,000
66,000
204,000
$1,500,000
420,000
288,000
288,000
$2,496,000
$ 183,000
$4,344,000
-'-See Appendix A for details of assumptions used in the cost analysis.
^Noncomponent costs include piping, electrical, instrumentation, and site
preparation.
^present worth computed assuming 20-year life at 7-5/8 percent interest
rate (PWF = 10.0983).
7K
-------
TABLE B-5. COST COMPARISON -- 18,925 m3/d (5.0 mgd) FACILITY1
CASE 2
PHOSPHORUS RIMOVAL (EFFLUENT TP = 2 rag/L)
ENR INDEX = 3875
Alternative
2-A
one-stage
activated
sludge
Process unit
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrif icat ion/Clarification
Ch lor i nation
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Haul ing/Landfill ing
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORT H^ COSTS3
with alum
addition
(baseline)
$ 705,000
196,000
438,000
2,035,000
62,000
___
191,000
_ _ _
310,000
250,000
204,000
470,000
658,000
251,000
$ 5,770,000
1,616,000
1,108,000
1,108,000
$ 9,602,000
$ 774,000
$17,418,000
Alternative
2-B
PhoStrip
$ 705,000
196,000
438,000
2,035,000
1,096,000
_ _
__ _
191,000
_ _
310,000
250,000
188,000
470,000
595,000
246,000
$ 6,720,000
1,882,000
1,290,000
1,290,000
$11,182,000
$ 690,000
$18,150,000
Alternative
2-C
A/0
$ 705,000
196,000
438,000
2,129,000
12,000
_ _ _
191,000
mt ^ ^
310,000
250,000
196,000
500,000
595,000
247,000
$ 5,769,000
1,615,000
1,108,000
1,108,000
$ 9,600,000
$ 641,000
$16,073,000
!See Appendix A for details of assumptions used in the cost analysis.
2Noncomponent costs include piping, electrical, instrumentation, and site
preparation.
3Present worth computed assuming 20-year life at 7-5/8 percent interest
rate (PWF = 10.0983).
76
-------
TABLE B-6. COST COMPARISON 189,250 m3/d (50.0 mgd) FACILITY1
CASE 2
PHOSPHORUS REMOVAL (EFFLUENT TP = 2 mg/L)
ENR INDEX = 3875
Process unit
Alternative
2-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative
2-B
PhoStrip
Alternative
2-C
A/O
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrification/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 3,600,000 $ 3,600,000
783,000
2,270,000
12,995,000
463,000
798,000
783,000
2,270,000
12,995,000
2,740,000
798,000
$ 3,600,000
783,000
2,270,000
11,797,000
230,000
798,000
1,190,000
1,000,000
391,000
2,740,000
2,818,000
467,000
$29,515,000
8,264,000
5,667,000
5,667,000
1,190,000
1,000,000
344,000
2,740,000
2,583,000
457,000
$31,500,000
8,820,000
6,048,000
6,048,000
1,190,000
1,000,000
360,000
2,818,000
2,583,000
467,000
$27,896,000
7,811,000
5,356,000
5,356,000
$49,113,000 $52,416,000
$ 4,890,000 $ 3,666,000
$98,494,000 $89,436,000
$46,419,000
$ 3,540,000
$82,167,000
-'See Appendix ft for details of assumptions used in the cost analysis.
2Noncomponent costs include piping, electrical, instrumentation, and site
preparation.
^Present worth computed assuming 20-year life at 7-5/8 percent interest
eate (PIP = 10.0983).
-------
TABLE B~7.
COST COMPARISON 1,892 m3/d (0.5 mgd)
FACILITY1
CASE 3
PHOSPHORUS REMOVAL AND NITRIFICATION
(EFFLUENT TP = 2 mg/L, NH3~N = 1 mg/L)
ENR INDEX = 3875
Process unit
Alternative
3-A
two-stage
activated
sludge
with alum
addition
(baseline)
Alternative
3-C
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip
Chemical Addition
Ni tr i f ication/Clarif ication
Denitrif icat ion/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
De water ing (Drying Bed)
Sludge Haul ing/ Land fill ing
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 188,000
47,000
122,000
411,000
25,000
360,000
_-_
63,000
96,000
78,000
125,000
78,000
204,000
$1,797,000
503,000
345,000
345,000
$2,990,000
$ 227,000
$5,282,000
$ 188,000
47,000
122,000
676,000
5,000
___
63,000
96,000
78,000
130,000
66,000
204,000
$1,675,000
469,000
322,000
322,000
$2,788,000
$ 195,000
$4,757,000
^See Appendix A for details of assumptions used in the cost
analysis.
^Noncoinponeiit costs include piping, electrical, instrumenta-
tion, and site preparation.
"'"esent worth computed assuming 20-year life at 7-5/8 percent
cerest rate (PWP = 10.0983).
^A/O also provides partial denitrification (effluent TN = 10
mg/L, NO3-N = 8 mg/L) .
-------
FACILITY1
iu-/u
CASE 3
PHOSPHORUS REMOVAL AND NITRIFICATION
(EFFLUENT TP = 2 mg/L, NH3-N = 1 mg/L)
ENR INDEX = 3875
Process unit
Alternative
3-A
two-stage
activated
sludge
with alum
addition
(baseline)
Alternative
3-C
A/04
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip
Chemical Addition
Nitrification/Clarification
Denitrification/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAP)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 705,000
196,000
438,000
1,614,000
62,000
1,487,000
191,000
310,000
250,000
204,000
470,000
658,000
251,000
$ 6,836,000
1,914,000
1,313,000
1,313,000
$11,376,000
$ 854,000
$20,000,000
705,000
196,000
438,000
2,728,000
12,000
191,000
310,000
250,000
196,000
500,000
595,000
247,000
$ 6,368,000
1,783,000
1,223,000
1,223,000
$10,596,000
$ 702,000
$17,685,000
!See Appendix A for details of assumptions used in the cost
analysis.
^Noncomponent costs include piping, electrical, instrumenta-
tion, and site preparation,
^Present worth computed assuming 20-year life at 7-5/8 percent
interest rate (PWF = 10.0983).
^A/0 also provides partial denitrification (effluent TN = 10
mg/L, NO3~N = 8 mg/L).
-------
TABLE B-9. COST COMPARISON 189,250 m3/d (50.0 mgd)
FACILITY1
CASE 3
PHOSPHORUS REMOVAL AND NITRIFICATION
(EFFLUENT TP = 2 Hig/L, NH3-N = 1 mg/L)
ENR INDEX = 3875
Process unit
Alternative
3-A
two-stage
activated
sludge
with alum
addition
(baseline)
Alternative
3-C
A/04
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip
Chemical Addition
Nitrification/Clarification
Denitrif ication/Clarif ication
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAP)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landf illing
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 3,600,000
783.000
2,270,000
8,510,000
-
463,000
8,768,000
798,000
1,190,000
1,000,000
391,000
2,740,000
2,818,000
467,000
$ 33,798,000
9,463,000
6,489,000
6,489,000
$ 56,239,000
$ 5,369,000
$110,457,000
$ 3,600,000
783,000
2,270,000
15,452,000
230,000
798,000
1,190,000
1,000,000
360,000
2,818,000
2,583,000
467,000
$31,551,000
8,834,000
6,058,000
6,058,000
$52,501,000
$ 3,952,000
$92,409,000
-"-See Appendix A for details of assumptions used in the cost
analysis.
2Noncomponent costs include piping, electrical, instrumenta-
tion, and site preparation.
3Present worth computed assuming 20-year life at 7-5/8 percent
interest rate (PWF = 10.0983).
also provides partial denitrif ication (effluent TN = 10
mg/L, NO3-N = 8 mg/L) .
-------
TABLE B-10, COST COMPARISON 1,892 m3/d (0.5 mgd)
FACILITY1
CASE 4
PHOSPHORUS RMGVAL, NITRIFICATION,
AND DENITRIFICATION (EFFLUENT TP = 2 mg/L, TN = 3 mg/L)
ENR INDEX = 3875
Process unit
Alternative
4-A
three-stage
activated
sludge
with alum
addition
(baseline)
Alternative
4-D
Bardenpho
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip
Chemical Addition
Nitrification/Clarification
Denitr if ication/Clarif ication
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Drying Bed)
Sludge Hauling/Landfilling
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL OSM COSTS
TOTAL PRESENT WORTH COSTS3
$ 188,000
47,000
122,000
411,000
___
25,000
360,000
266,000
63,000
96,000
78,000
125,000
78,000
204,000
62,063,000
578,000
396, OCO
396,000
$3,433,000
$ 274,000
$6,200,000
$ 188,000
47,000
122,000
835,000
63,000
___
96,000
78,000
94,000
67,000
181,000
$1,771,000
496,000
340,000
340,000
$2,947,000
$ 190,000
$4,866,000
*-See Appendix A for details of assumptions used in the cost
analysis.
%oncomponent costs include piping, electrical, instrumenta-
tion, and site preparation.
-^Present worth computed assuming 20-year life at 7-5/8 percent
interest rate (PWF = 10.0983).
81
-------
TABLE B-ll. COST COMPARISON -- 18,925 m3/d {5.0 mgd)
FACILITY1
CASE 4
PHOSPHORUS REMOVAL, NITRIFICATION, AND DENITRIFICATION
(EFFLUENT TP = 2 jng/L, TN = 3 mg/L}
ENR INDEX ~ 3875
Process unit
Alternative
4-A
three-stage
activated
sludge
with alum
addition
(baseline)
Alternative
4-D
Bardenpho
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip
Chemical Addition
Nitrification/Clarification
De nitrification/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landf illing
Sub-Total
Noncomponent Costs-**
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 705,000
196,000
438,000
1,614,000
__..
62,000
1,487,000
924,000
191,000
310,000
250,000
204,000
470,000
658,000
251,000
$ 7,760,000
2,173,000
1,490,000
1,490,000
$12,913,000
$ 1,112,000
$24,142,000
$ 705,000
196,000
438,000
3,815,000
___
191,000
310,000
250,000
164,000
344,000
595,000
219,000
$ 7,227,000
2,024,000
1,388,000
1,388,000
$12,026,000
$ 701,000
$19,105,000
%ee Appendix A for details of assumptions used in the cost
analysis.
%oncomponent costs include piping, electrical, instrumenta-
tion, and site preparation.
3Present worth computed assuming 20-year life at 7-5/8 percent
interest rate (PWF = 10.0983).
82
-------
TABLE B-12. COST COMPARISON -- 189,250 m3/<3 (50.0 mgd)
FACILITY1
CASE 4
PHOSPHORUS REMOVAL, NITRIFICATION, AND DENITRIFICATIQN
(EFFLUENT TP = 2 mg/L, TN = 3 mg/L)
ENR INDEX = 3875
Process unit
Alternative
4-A
three-stage
activated
sludge
with alum
addition
(baseline)
Alternative
4-D
Barctenpho
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip
Chemical Addition
Nitrification/Clarification
Denttrification/Clarification
Chlotination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling
Sub-Total
Noncomponent Costs^
Engineering and Construction
Supervision
Contingency
TOTAL CAPITAL COSTS
ANNUAL O&M COSTS
TOTAL PRESENT WORTH COSTS3
$ 3,600,000
783,000
2,270,000
8,510,000
463,000
8,768,000
5,010,000
798,000
1,190,000
1,000,000
391,000
2,740,000
2,818,000
467,000
$ 38,808,000
10,866,000
7,451,000
7,451,000
$ 64,576,000
$ 7,469,000
$140,000,000
3,600,000
783,000
2,270,000
26,460,000
798,000
1,190,000
1,000,000
297,000
1,957,000
2,583,000
373,000
$ 41,311,000
11,567,000
7,932,000
7,932,000
$ 68,742,000
$ 4,219,000
$111,347,000
Isee Appendix A for details of assumptions used in the cost
analysis.
%oncomponent costs include piping, electrical, instrumenta-
tion, and site preparation.
^present worth computed assuming 20-year life at 7-5/8 percent
interest rate (PWF = 10.0983).
83
-------
TABLE B-13. ENERGY ANALYSIS (ID3 kwh/y) 1,892 m3/d
(0.5 mgd) FACILITY1
CASE 1
PHOSPHORUS REMOVAL (EFFLUEtMT TP = 1 mg/L)
Alternative
1-A
one-stage
activated
sludge
with alum
addition
(baseline)
Process unit
Alternative
1-B
PhoStrip
Alternative
1-C
A/0
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrif ication/Clarif ication
Chlorination
-Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Drying Bed)
Sludge Hauling/Landf illing2
Total, 10 3 kwh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
9
12
8
135
---
8
4
_-_
90
43
309
447
1.69
9
12
8
135
55
-__
4
-
90
40
353
511
1.93
9
12
8
1573
4
4
34
100
38
366
527
1.99
l-See Appendix A for details of assumptions used in cost anal-
ysis.
^Energy equivalent of diesel oil in kwh.
^Including energy for internal flow recycle (see Appendix A) .
84
-------
TABLE 8-14. ENERGY ANALYSIS (103 kwh/y) 18,925 JB3/d
{5.0 mgd) FACILITYl
CASE 1
PHOSPHORUS REMOVAL (EFFLUENT TP = 1 mq/L)
Process unit
Alternative
1-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative Alternative
1-B 1-C
Pho Strip A/O
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrification/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling^
90
25
45
1,350
40
39
90
25
45
1,350
1053
39
120
900
75
397
90
25
45
1,2603
20
39
325
150
950
75
374
Total, 10 3 kwh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
3,171
459
1.74
3,146
455
1.72
3,353
485
1.84
3-See Appendix A tor details of assumptions used in cost anal-
ysis.
28nergy equivalent of diesel oil in kwh.
Including energy for internal flow recycle (see Appendix A) .
-------
TABLE B-15. ENERGY ANALYSIS (103 Rwh/y) 189,250 m3/d
(50.0 mgd) FACILITY^
CASE 1
PHOSPHORUS REMOVAL (EFFLUENT TP = 1 mg/L)
Process unit
Alternative
1-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative Alternative
1-B 1-C
PhoStrip A/0
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Deni tr if icat ion/ Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landf illing2
Total, 10 3 kwh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
900
80
300
13,500
400
390
---
1,150
210
850
4,170
21,950
318
1.20
900
80
300
13,500
2103
390
750
210
650
3,970
20,960
303
1.15
900
80
300
12f 6003
-__
59
___
-
390
3,100
-.--
1,000
240
650
4,170
23,489
340
1,29
Appendix A for details of assumptions used in cost anal-
ysis
^Energy equivalent of diesel oil in kwh.
3Including energy f cr internal flow recycle (see Appendix A) .
86
-------
TABLE B-16. ENERGY ANALYSIS (103 kwh/y) 1,892 m3/d
(0.5 mgd) FACILITY!
CASE 2
PHOSPHORUS RSMOVAL (EFFLUENT TP = 2 mg/L)
Process unit
Alternative
2-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative Alternative
2-B 2-C
PhoStrip A/O
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrif ication/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Drying Bed)
Sludge Haul ing/Land fill ing 2
Total, 103 kWh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
9
12
8
135
-
8
_
,
4
_
_
__._
90
43
309
447
1.69
9
12
8
135
553
_
4
-,-»
mm mm *
-,
_
90
___
40
353
511
1.93
9
12
8
1573
4
*.*.,*
4
«M»
mm w _ .
».*...
100
38
332
481
1.82
ysis
Appendix A for details of assumptions used in cost anal-
2Energy equivalent of diesel oil in kwh.
3lncluding energy for internal flow recycle (see Appendix A) .
87
-------
TABLE B-17. ENERGY ANALYSIS (103 kwh/y) 18r925 m3/d
(5,o mgd) FACILITY!
GASfi 2
PHOSPHORUS REMOVAL (EFFLUENT TP = 2 mg/L)
Process unit
Alternative
2-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative Alternative
2-B 2-C
PhoStrip A/0
Low Lift Pumping 90 90
Preliminary Treatment 25 25
Primary Treatment 45 45
Aeration/Clarification 1,350 1,350
PhoStrip (with Lime Addition) 1053
Chemical Addition 40
Nitrification/Clarification
Denitrification/Clarification ---
Chlorination 39 39
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF> 170
Digestion (Aerobic) 900
Dewatering (Vacuum Filter) 95
Sludge Hauling/Landfilling2 417
Total, 103 kwh/y 3,171 3,146
Unit Energy Utilization,
kwh/1,000 m3 459 455
kwh/1,000 gals 1.74 1.72
90
25
45
20
39
150
950
75
374
3,028
438
1.66
1-See Appendix A for details of assumptions used in cost anal-
ysis.
^Energy equivalent of diesel oil in kwh.
^including energy for internal flow recycle (see Appendix A).
88
-------
TABLE B-18. ENERGY ANALYSIS (103 kwh/y) 189,250 m3/d
(50.0 mgd) FACILITY-1-
CASE 2
PHOSPHORUS REMOVAL (EFFLUENT TP = 2 mg/L)
Process unit
Alternative
2-A
one-stage
activated
sludge
with alum
addition
(baseline)
Alternative Alternative
2-B 2-C
PhoStrip A/O
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrificat ion/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling2
900
80
300
13,500
400
390
_ __
___
___
1,150
210
850
4,170
900
80
300
13,500
2103
_.._
»
390
_ _ _
_ _ .
»
750
210
650
3,970
900
80
300
12,6003
59
V.
390
» w
1,000
240
650
4,170
Total, 103 kwh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
21,950
20,960
318
1.20
303
1.15
20,389
295
1.12
ysis
Appendix A for details of assumptions used in cost anal-
2Energy equivalent of diesel oil in kwh.
3Including energy for internal flow recycle (see Appendix A) .
89
-------
TABLE B-19. ENERGY ANALYSIS (1Q3 kwh/y} 1,892 m3/d
(0.5 mgd) FACILITY.1
CASE 3
PHOSPHORUS REMOVAL AMD NITRIFICATION
(EFFLUENT TP = 2 mg/L, NH3-N = 1 mg/L)
Alternative
3-A
two-stage
activated
sludge
with alum Alternative
addition 3-C
Process unit (baseline) A/0
Low Lift Pumping 9 9
Preliminary Treatment 12 12
Primary Treatment 8 8
Aeration/Clarification 118 2653
PhoStrip (with Lime Addition)
Chemical Addition 8 4
Nitrification/Clarification 101
Denitrification/Clarification
Chlorination 4 4
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic) 90 100
Dewatering (Drying Bed}
Sludge Hauling/Landfilling2 _43 38
Total, 103 fcwh/y 393 440
Unit Energy Utilization,
kwh/1,000 m3 569 637
kwh/1,000 gals 2.15 2.41
1-See Appendix A for details of assumptions used in cost anal-
ysis.
^Energy equivalent of diesel oil in kwh.
3lncluding energy for internal flow recycle and credit for en-
ergy reduction due to recycle of nitrate (see Appendix A).
90
-------
TABLE B-20. ENERGY ANALYSIS (ID3 kwh/y) 18,925 m3/d
(5.0 mgd) FACILITY*-
CASE 3
PHOSPHORUS REMOVAL AND NITRIFICATION
(EFFLUENT TP = 2 mg/L, NH3-N = 1 mg/L)
Alternative
3-A
two-stage
activated
sludge
with alum Alternative
addition 3-C
Process unit (baseline) A/0
Low Lift Pumping 90 90
Preliminary Treatment 25 25
Primary Treatment 45 45
Aeration/Clarification 984 1,9903
PhoStrip (with Lime Addition)
Chemical Addition 40 20
Nitrification/Clarification 1,010
Denitrification/Clarification
Chlorination 39 39
Effluent Filtration -
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling^
Total, 103 kwh/y 3,815 3,758
Unit Energy Utilization,
kwh/1,000 m3 552 544
kwh/1,000 gals 2.09 2.06
J-See Appendix A for details of assumptions used in cost anal-
ysis.
^Energy equivalent of diesel oil in kwh.
3Including energy for internal flow recycle and credit for en-
ergy reduction due to recycle of nitrate (see Appendix A).
-------
TABLE B-21. ENERGY ANALYSIS (103 kwh/y) 189,250
(50,0 mgd) FACILITY-1-
CASE 3
PHOSPHORUS REMOVAL AND NITRIFICATION
(EFFLUENT TP = 2 mg/L, NH3-N - 1 mg/L)
Alternative
3-A
two-stage
activated
sludge
with alum Alternative
addition 3-C
Process unit (baseline) A/0
Low Lift Pumping 900 900
Preliminary Treatment 80 80
Primary Treatment 300 300
Aeration/Clarification 9,352 18,6643
PhoStrip (with Lime Addition)
Chemical Addition 100 59
Nitrification/Clarification 10,10^
Denitrification/Clarification >-
Chlorination 390 390
Effluent Filtration - ---
Gravity Outfall ---
Miscellaneous Structures ---
Thickening (DAP) 1,150 1,000
Digestion (Aerobic) 210 240
Dewatering (Vacuum Filter) 850 650
Sludge Hauling/Landfilling2 4f170 4,170
Total, 103 kwh/y 27,902 26,453
Unit Energy Utilization,
kwh/1,000 m3 404 382
kwh/1,000 gals 1.53 1.45
-'-See Appendix A for details of assumptions used in cost anal-
ysis.
2Energy equivalent of diesel oil in kwh.
3Including energy for internal flow recycle and credit for en-
ergy reduction due to recycle of nitrate (see Appendix A).
92
-------
TABLE B-22. ENERGY ANALYSIS (103 kwh/y) 1,892 ra3/d
(0.5 mgd) FAeiLITy.1
CASE 4
PHOSPHORUS REMOVAL, NITRIFICATION, AND DENITRIFICATION
(EFFLUENT TP = 2 mg/L, TN = 3 mg/L>
Process unit
Alternative
4-A
three-stage
activated
sludge
with alum
addition
(baseline)
Alternative
4-D
Bardenpho
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clari fication
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrification/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Drying Bed)
Sludge Hauling/Landfilling2
Total, 103 kwh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
9
12
B
118
8
101
24
4
90
43
417
604
2.28
9
12
8
2723
55
34
383
555
2.10
Appendix A for details of assumptions used in cost anal-
ysis.
^Energy equivalent of diesel oil in kwh.
^Including energy for internal flow recycle and credit for en>
ergy reduction due to recycle of nitrate (see Appendix A).
93
-------
TABLE B-23. ENERGY ANALYSIS (103 kwh/y} -- 18,925 m3/d
(5.0 ragd) FACILITYl
CASE 4
PHOSPHORUS RBlOvAL, NITRIFICATION, AND DENITRIF1CATIOM
(EFFLUENT TP = 2 flif/Lf Tfi = 3 mg/L)
Process unit
Alternative
4-A
three-stage
activated
sludge
with alum
addition
(baseline)
Alternative
4-D
Bardenpho
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrification/Clarification
Chlorinatiori
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAF)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling^
Total, 103 kwh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
90
25
45
984
40
1,010
220
39
4,035
584
2.21
90
25
45
2,5853
39
3,832
555
2.10
Appendix A for details of assumptions used in cost anal-
ysis
^Energy equivalent of diesel oil in kwh.
^Including energy for internal flow recycle and credit for en-
ergy reduction due to recycle of nitrate (see Appendix A) .
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TABLE B-24. ENERGY ANALYSIS (103 kwh/y) 189,250 m3/d
(50.0 mgd) PACILITYJ-
CASE 4
PHOSPHORUS REMOVAL, NITRIFICATION, AND DENITRIFICATION
(EFFLUENT TP = 2 mg/L, TN = 3 mg/L)
Process unit
Alternative
4-A
three-stage
activated
sludge
with alum
addition
(baseline)
Alternative
4-D
Bardenpho
Low Lift Pumping
Preliminary Treatment
Primary Treatment
Aeration/Clarification
PhoStrip (with Lime Addition)
Chemical Addition
Nitrification/Clarification
Denitrification/Clarification
Chlorination
Effluent Filtration
Gravity Outfall
Miscellaneous Structures
Thickening (DAP)
Digestion (Aerobic)
Dewatering (Vacuum Filter)
Sludge Hauling/Landfilling2
Total, 103 kwh/y
Unit Energy Utilization,
kwh/1,000 m3
kwh/1,000 gals
900
80
300
9,352
400
10,100
2,100
390
1,150
210
850
4,170
30,002
434
1.64
900
80
300
25,8503
390
500
115
650
3,340
32,125
465
1,76
Appendix A for details of assumptions used in cost anal-
ysis.
^Energy equivalent of diesel oil in kwh.
3Including energy for internal flow recycle and credit for en-
ergy reduction due to recycle of nitrate (see Appendix A).
95
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APPENDIX C
RESPONSE OF PROPRIETARY FIRMS
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Air Products and Chemicals, fr>c.
Box 538- Allenscwrv PA 18105
(215)481-4911
11 April 1984
Mr. Edwin Barth
U.S. ENVIRONMENTAL PROTECTION AGENCY
Municipal Environmental Research Lab
Wastewater Research Division
26 W. St. Clair Street
Cincinnati, Ohio 45268
Dear Mr. Barth:
Thank you for the opportunity to comment on the report, "Emerging Technology
Assessment for Biological Phosphorus Removal" prepared by Roy F. Weston, Inc.
In general, we are pleased with the report and feel it accurately represents
the state of the art of the A/0 technology, I would like to comment in more
detail in two areas. The first area concerns the discussion of the performance
of the process to which I would like to add some thoughts. In the second area,
cost comparisons, we feel strongly that the analysis given does not reflect
the magnitude of cost savings available to users of A/0.
A. A/0 Performance
The concentration of phosphorus in the effluent from a properly designed
A/0 plant will be mainly dependent upon the ratio of BOD to phosphorus of
the wastewater treated. Our experience has shown when this ratio exceeds
10 to 1, an effluent soluble phosphorus of 1 ing/1 or less can be expected.
At ratios less than 10 to 1 the A/0 process continues to function, but
with increasing effluent phosphorus levels as the ratio decreases. One
method of assuring performance to less than 1 mg/1 total P is the combina-
tion of A/0 with chemical precipitation. In this method, alum would be
added either upstream to adjust the BOD:P ratio to the proper level or
downstream to precipitate residual phosphorus. By combining A/0 with
chemicals where BOO:P may be less than 10:1, permit compliance is guaranteed
while cost savings compared with the straight chemical approach will always
be obtained.
B. Cost Comparisons
A major portion of the report is an analysis of the costs of biological
phosphorus removal compared with chemical phosphorus removal. The large
97
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Mr. Edwin Barth
11 April 1984
Page Two
number of figures and tables does not seem justified since simplified
assumptions and inconsistent methods of estimating the component costs
were used. Specifically:
1. Some construction costs were reported to be estimated using the EPA
I&A manual while other components are estimated using Weston in-house
procedures. Cost estimates should be on an equal basis or at least
some comparison of Weston methods with I&A manual methods provided.
A discussion of the major differences among the processes and the
impact on the cost would be Vi ry helpful to a designer considering
using the A/0 process.
2. The method of estimating the O&M costs is not given. No cost breakdown
is given to indicate where differences in operating cost arise. The
dosage and unit cost of chemicals are not given.
Operating cost savings from lower chemical usage and less sludge pro-
duction are a major incentive to prospective users of biological
phosphorus removal plants. If this reoort is to accurately assess
the value of biological phosphorus removal, additional discussion and
further detail is needed in this area.
3. No consideration is given to retrofit of existing activated sludge plants.
Retrofit of A/0 can often lead to large operating cost savings over the
life of the plant.
4. The relative cost advantage of biological phosphorus removal is made to
appear small by adding other non-phosphorus removal related components
to arrive at a "total" cost figure.
5. The cost of tertiary filters appears high. For example, the actual bid
installed cost for an Enelco brand filter for the City of Largo (15
MGD, bid November 1981) installed in an existing concrete shell was
$850,000. The figure given in the report for a 5 MGD case including
concrete is $1,300,000.
6. It is assumed that the A/0 process will require effluent filtration to
meet a 1 mg/1 total P standard. A much less expensive method would be
to supplement with chemicals.
It should be recognized that chemical phosohorus removal processes will
also produce a phosphorus rich sludge and may require effluent filters
to meet 1 mg/1. For example, a typical activated sludge plant treating
98
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Mr. Edwin Barth
11 April 1984
Page Three
150 mg/1 BOD (after primaries) with an overall sludge yield of 0.8
Ib. solids/lb. BOD removed will produce 1000 pounds of waste sludge
per million gallons. If alum is added at a dosage of 15.0 mg/1
(as A!*4"1") to precipitate 10 mg/1 phosphorus, an additional 437 pounds
of sludge will be made totaling 1437 pounds of waste sludge. This will
contain 75 pounds of phosphate resulting in a sludge phosphate content
of 5.221, Solids contained in the effluent will reflect increased
phosphorus content.
Ed, thanks for your consideration in allowing me to comment on this report. I
hope this will be of value to you.
Sincerely,
David J. Krichten
Technical Specialist
Environmental Products Department
DJK/cah
99
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Process HAP III
Et>uiPW«>t *.>*l« "- ts West Second Souih
Company Posl Office Box 300
Salt Lake City, Utah 84110-0300
Telephone 801/526-2000
Telex 388-331 or 388-320
March 9, 1984
Mr. Ed Barth
Chief Biological Treatment Section
Wastewater Research Division
United States Environmental Protection
SSI, I'S *-
Subject: Edging Technology Assessnent Qf B.
Dear Ed,
as
Process Equipmenl cojLS 2
I^p^
s ^«t that the
where denitrif cat on ic f h°-1d be C0ns"ered only in
removal. We strongly objec? to tli^ iuT"^^ 1n add^ioHto phosphorus
incorrect and fails to S«,£ 5 Judgement and believe it is both
tt
srVl shH
from the presentations from Eimcn 7nrf nit. !? uld be abljndantly clear
eeptors, especially nitrate fl^a?J.ot?ers that Control of all electron ac
fermentation perf^mancf a'nd ttSs emSlnfTT1?1*6 t0 prop^ "
The introduction of nitrate to the ferment ^tS°logical Phosphorus removal.
if proper fermentation and pSsSSruf JS2S I re!Ct0r must be av°1ded
Process does not evade this issue inLmlh » f! f° ^ccur' The Bardenpho
KSmPl2ShSd Wlthin the Bardenpho Howsheet F?^1 ,n\t-r°9en cmtl isP
Bardenpho Process provides a positive JpfLi C°^elleves that th^
assures that nitrate cannot deterioratP h I?nn- c?nfZ9°rat1on Wh1c«
No other configuration provid" Si «sSrJi? lcaj Ph?sPhos removal.
Proy1des nitrogen removal, evln whin sochlf ^ The ^Ct that
"
assumption that a two or three st* cJ + ' Seems to be based on the
a five stage system. This assumption Is erroneou^ ^ ?xpen!1ve tna"
''**e i L Tai l es to
100
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Mr, Ed Barth March 9, 1984
Page 2
recognize that a rational process design will be based on providing the
necessary SRT to provide the required effluent quality in terms of BOD
and ammonia. As such the reactor volume should be nearly equalivant
regardless of the number of stages employed. Eimco believes that it is
best to divide that reactor volume into five stages to provide nitrogen
control for reasons discussed above. The difference, therefore, relates
to the number of inner partition walls and the specific function of the
subreactors created by location of those partition walls. With that
in mind, it seems clear to us that a five stage reactor, which accounts
for the potential of nitrate formation during various seasons or operating
conditions at a full scale facility, and develops energy and akalinity
restoration benefits as a result of denitrification, is the preferred
configuration for applications requiring phosphorus removal.
Now it is true that many of the Bardenpho Process designs in the United
States have been based on long SRT operation. The reason for this relates
to the fact that most of these situations involve applications requiring
total nitrogen control to levels of the order of 3 mg/£ TN. With the
relatively longer SRTs required to assure achieving less than 1 mg/£
ammonia, and the anoxic volume required to achieve an effluent of
1-2 mg/£ nitrate, it becomes obvious that utilizing only a slightly
larger SRT could result in the production of a stab!ized sludge eliminating
the need for additional costly digestion and eliminating concerns of
phosphorus release during the digestion process. We would stress, however
that this is a detailed design decision made by the engineer outside
the scope of whether a two, three or five stage system is employed.
Therefore, Eimco would like to see this judgement and statements concluding
where Bardenpho's "greatest market potential exists" removed from the
Summary Document. For your reference, the most obvious examples of this
appear on page V, 14, & 53.
Secondly, there is a general implication and specific statements made
to the effect that the Bardenpho process capability to achieve effluent
phosphorus values of less than 2 mg/£ is not demonstrated. The only two
operating Bardenpho plants in North America disproved this statement.
The Kelona, British Columbia facility, which was reported on at both
sessions of this workshop, has consistently produced an effluent of
less than 1 mg/£ phosphorus after its initial acclamation period while
the Palmetto, Florida Bardenpho facility presently averages 1.5 mg/£
effluent P without chemical addition. This level of performance at
Palmetto can be directly attributed to the fact that the influent waste-
water BOD concentration is unusually weak for domestic wastewater and
less than 50% of the design value. Labeling the Bardenpho process as
incapable or unproven in producing effluent phosphorus values better
than 2 mg/£ would seem to not be justified. We are concerned that
this statement in the Summary Document will be taken out of context by
others and interpreted in far too general a context. To prevent this,
101
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Mr. Ed Barth March 9, 1984
Page 3
we respectfully request that statements to this effect be removed from
Summary Document. Such statements are found, for example, on pages
14 & 28.
Thirdly, the summary document presents numerous cost analyses of the
various biological phosphorus removal flow sheets. In the first place,
the cost analyses again relegate Bardenpho only to those applications
requiring denitrification with no consideration given to the technical
and economic benefits of Bardenpho in other applications evaluated. More
importantly, we have serious reservations about the validity of the cost
analyses performed. For example, the Bardenpho Process was designed
arbitrarily and based on nominal detention times. The dentention times
arbitrarily selected are, for the most part, higher than that normally
found in U.S. Bardenpho Process designs based on rational design approaches.
Therefore, we feel that the results of these cost analyses, particularly
where the Bardenpho Process is involved are neither accurate for the
general case nor even for the example selected for this analysis. Actual
bid prices taken on several commercial plants during the past one - two
years testify to the inaccuracy of the cost analysis.
Our concern, of course, is that these analyses will be used and abused
as consulting engineers attempt to evaluate relative cost and performance
effectiveness of the Bardenpho Process. Process selection decisions will
be made on the basis of these analyses and these decisions may,, in many
cases, be in error. Doubting that process selection decisions will be
made based on these cost analyses is naive. There are many const!ting
engineers in the United States today who utilize general cost information
such as that found in the EPA I&A Technology Manual and the infamous
CAPDET program. This is done because it is not only the easiest thing
to do, but also readily accepted since the cost information is generally
associated with having been developed by various agencies of the Federal
Government such as the EPA and The Corps of Engineers.
Therefore, Eimco believes that presenting generalized cost information
such as that presented in the Summary Document is risky, inappropriate,
and in fact serves no real benefit. On the other hand, there is an
unfortunate opportunity for misuse of that information. Thus Eimco has
a strong preference to have this cost information removed from the Summary
Document,
In addition, there are several statements made in the Summary Document
which we believe are inaccurate. Without trying to be too picky, we
would just highlight two of them here. First, on page 56, a statement
is made that "some of the failures associated with the Bardenpho System
have been related to low COD:TKN ratios in the feed to the system". This
statement is really not accurate. In our opinion, the COO'.TKN ratio
was not a problem at all, but rather the inadequacy of the design to account
102
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Mr. Ed Earth March 9S 1984
Page 4
for the quantities of nitrate produced and reduced in the system. As
such, there was excessive residual nitrate in the system which deteriorated
phosphorus removal capability. As stated earlier in this letter, this
is precisely why Eimco feels so strongly that biological phosphorus
removal flowsheets must be capable of total nitrogen control.
The authors of the summary document briefly discussed operation and
maintenance considerations on page 20, In that section* they state that
the Bardenpho Process is more complicated than PhoStrip or AO since the
former involves both phosphorus and nitrogen removal. We simply can't
understand how the author can come to that conclusion with any understanding
of the various mechanisims operative in a biological phosphorus removal
flowsheet. I'm sure you can understand our difficulty with this conclusion,
considering nur conviction that a five stage Bardenpho design is operation-
ally stable anJ forgiving since there are no swings in nitrification or
denitrification on a daily or seasonal basis. Such may not be the case
for process designs based on the ragged-edge of nitrification SRT values
with inadequate capability to respond to various denitrification require-
ments. The inherent stability of the Bardenpho Process is even more
obvious in situations where long SRTs are employed to achieve sludge
stablization. Thus, we find the statement that Bardenpho is more difficult
to operate to be not only unjustified, but actually opposite to the real
situation. We trust that the authors will have no problem in correcting
this conclusion in their report after considering the process related
aspects of each of the flowsheets more carefully.
Ed, I trust that the comments contained herein will find acceptance by
yourself and the authors of the Summary Document, I also understand that
the Document is being reviewed by two extramural parties. I am hopeful
that these parties will also bring some of the issues raised in this
letter to the attention of the authors for consideration. I will look
forward to hearing from you on these issues and will be more than happy
to discuss them in more detail as necessary.
Sincerely yours,
Ejmco Process Equipment Company
DD/ms
David DiGregorio, Manager
Process Marketing & Development
103
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Comments on "Emerging Technology Assessment
of Biological Phosphorus Removal"
G.V, Levin, Biospherics Incorporated
1. Abstract - p.v., first paragraph, why not mention effect of I + A
funding and construction grant program on present worth costs fco
the community? These programs have major impact on capital costs
to the community, particularly in comparing the new processes,
which are eligible for I + A, to the baseline process which it is
not.
2. Table 5, p. 37, same as 1. above.
3. Pig. 5a, p. 43, same as 1. above.
4. Table 6, p. 38, should compare apples to apples; either PhoStrip at
2 mg/1 TP effl. or alternatives at 1 mg/1 TP effl. I think the
latter is more appropriate since most effl. stds. are 1.0 mg/1 T.P.
5. Table 6, p, 38, since $ crossover for PhoStrip occurs soon after
5 mgd is passed {see p. 53, first bullet) why not extrapolate point
where crossover in present worth occurs and show it in Table?
6. p. 3, 9th line from bottom, after "Figure 1," strike "or" and after
"primary effluent" insert "or recycled stripper sludge."
7. p. 3, bottom line, add "A variety of other PhoStrip modes has been
described by Biospherics, ranging from elimination of stripper tank
through use of existing tankage for sludge stripping to a no chemicals
version, buL none has been demonstrated full-scale."
8. p. 3, 18th line from top, delete comma between "Biospherics" and "Inc."
(ibid wherever else occurring}.
9. p. 3, line 22, after "activated" add "air or oxygan."
10. p. 4, Figure 1, Direct Sludge Recycle is given as "(0.2 to 0.3Q)". I
think it should be stated "(0.2 to 0.5Q)" since the process has fre-
quently been operated at 50 percent direct return sludge. This change
would require corresponding change for "Phosphorus-Enriched Sludge" to
"(0.2 to 0.5Q)." Also, "Elutriation Prom Either:" should be "Elutri-
ation Prom any of:" to be grairanatical.
11. p. 11, 12th line from bottom, after "selection," I suggest insertion
of "or inducement." This is because there is still no definitive word
on whether the population is selected or whether P-uptake and release
results from enzyme inducement in the general biota. The same addition
would be made three lines below this where "selection" appears again.
104
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12. p. 15, 13th line from bottom, if suggestion 10 above is accepted,
change "0.3" to "0.5."
13. Reference 4, change "Experimentia" to "Experienta."
14. Reference 11, Change "Tarmy" to "Tarnay."
15, Reference 13, change "Masse" to "Maase," and "J.J. Kish" to "A.J.
Kish," and delete comma after Biospherics.
16. Reference 31, remove comma after "Biospherics."
105
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