SEPA
United States
Environmental Protection
Agency
2023 Revision* to:
Life Cycle and Cost Assessments of
Nutrient Removal Technologies in
Wastewater Treatment Plants
* This 2023 revision entails errata regarding nitrous oxide emissions from
wastewater biological treatment processes, as described on the next page.
Prepared for:
U.S. Environmental Protection Agency
Standards and Health Protection Division
Office of Water, Office of Science and Technology
1200 Pennsylvania Avenue NW (4305T)
Washington, DC 20460
Prepared by:
Eastern Research Group, Inc.
110 Hartwell Ave
Lexington, MA 02421
August 2021
EPA 832-R-21-006A
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Errata
Errata
In 2023, EPA identified an error in Equation F-3, used to calculate nitrous oxide (N2O)
emissions from wastewater biological treatment processes. This equation, located on page F-2,
included an incorrect molecular weight conversion factor of N to N2O of 44/14. The correct
conversation factor is 44/28. See the errata sheet located at the end of this document for more
information.
KP-C-16-003; WA 2^37
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Executive Summary
Executive Summary
Human-caused nutrient enrichment of waterbodies from excessive nitrogen (N) and
phosphorus (P) is one of the most pervasive environmental issues facing the United States (U.S.
EPA, 2015a). In many watersheds, municipal and industrial wastewater treatment plants
(WWTPs) can be major point sources of nutrients. Recent efforts to derive numeric nutrient
criteria to protect the designated uses of waterbodies have resulted in limits that may be
challenging to meet for most WWTPs in the United States with the treatment configurations
currently in place. However, many stakeholders have expressed concern that there may be
significant undesirable environmental and economic impacts associated with upgrading
treatment configurations, as these configurations may require greater use of chemicals and
energy, release more greenhouse gases, and generate greater volumes of treatment residuals for
disposal.
The impacts can be assessed using holistic, systematic approaches using life cycle impact
assessment (LCIA) and life cycle cost analysis (LCCA). These approaches provide a "cradle-to-
grave" analysis of the environmental impacts and benefits as well as the economic costs and
benefits associated with individual products, processes, or services throughout their life cycle.
This study used LCIA and LCCA approaches to assess cost, human health, and ecosystem
metrics associated with nine distinct wastewater treatment configurations designed to reduce the
nutrient content of effluent from municipal WWTPs.
Table ES-1 depicts the five different total nitrogen and phosphorus treatment levels used
to configure nine different wastewater treatment systems commonly used in the U.S. to achieve
the specified nutrient concentrations. Level 1 represents a standard secondary treatment
configuration with no additional processes for nutrient removal. For Levels 2-5, two
configurations that could meet the performance target were selected per level, representing
contrasts in factors such as biological processes, costs, and energy requirements. Each
configuration was modeled with an average flow rate of 10 million gallons per day (MGD) and a
maximum flow rate of 20 MGD.
Table ES-1. Target Effluent Nutrient Concentrations by Level
Level
Total Nitrogen. mg/L
Total Phosphorus, mg/l.
1
no target specified
no target specified
2
8
1
3
4-8
0.1-0.3
4
3
0.1
5
<2
<0.02
For the life cycle impact assessment, this study considered 12 impact categories:
eutrophication potential, cumulative energy demand, global warming potential, acidification
potential, fossil depletion, smog formation potential, human health-particulate matter formation
potential, ozone depletion potential, water depletion, human health-cancer potential, human
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Executive Summary
health-noncancer potential, and ecotoxicity potential. The majority of impact categories address
air and water environmental impacts, while three categories are human health impact indicators.
Eutrophication potential (i.e., potential for enrichment of waterbodies with nutrients) is
the combined effect of direct nutrient discharges in the effluent, landfilled sludge leachate, and
the water discharges and air emissions from upstream inputs such as electricity and chemical
production. Eutrophi cation potential decreased dramatically between Level 1 and Level 2 and to
a smaller degree between Level 2 to Levels 3 and 4, which were similar to each other. Level 5
had higher eutrophi cation potential than Level 4 due to the energy requirement of reverse
osmosis and brine injection, which off-set the impact reduction associated with the lower effluent
nutrient concentration. However, based on the uncertainty thresholds for impact results, the
difference between Level 3, Level 4 and Level 5 is not considered significant.
Cumulative energy demand, acidification potential, fossil depletion, smog formation
potential, particulate matter formation, and global warming potential all showed a roughly
similar trend. The values for these categories all increased from Level 1 to Level 5 due to
increasing electricity use and natural gas heating consumption required to achieve the lower
nutrient values for the treatment systems selected.
Water depletion results were dominated by the high-water use of Level 5 treatment
configurations, approximately 100 times the other configurations, primarily for deepwell
injection of brine. The potential for reuse of wastewater following Level 5 treatment was not
considered in this study.
Although not specifically designed for it, the treatment configurations may also remove
trace pollutants (metals, toxic organics, and disinfection by-products [DBPs]) from effluent,
providing a toxicity reduction co-benefit. For configuration Levels 1-3, metals in liquid effluent
dominated toxicity impacts, whereas for Level 5, contributions from material and energy inputs
dominated, with Level 4 configurations having significant contributions from both sources. For
human health-cancer potential, Levels 1, 3, and 4 had lower impacts than Levels 2 and 5,
whereas for human health-noncancer potential, toxicity impacts decreased as treatment became
more advanced For ecotoxicity, Levels 3, 4, and 5 had lower toxicity than Levels 1 and 2.
Overall, one of the Level 4 configurations and, to a lesser degree, one of the Level 3
configurations stood out in most effectively balancing effluent toxicity reductions against the
increase in materials and energy required. Uncertainty for the toxicity impact assessment was
greater than for other impacts due to trace pollutant data limitations and to uncertainty inherent
in the impact estimation method (USEtox™).
The life cycle cost analysis provided results for capital costs, annual operation and
maintenance costs, and net present value, which combines the capital and operation and
maintenance costs into a single cumulative value (all in 2014$). In general, the net present value
increased with increasing nutrient control levels. The Level 2 configurations were an exception
to the trend due to the high annual costs associated with the three separate biological units.
Sensitivity analyses considered different interest rates, electricity grid composition,
improved energy capture at the facility, and a retrofit scenario instead of building a new facility.
Since electricity was a primary driver for many of the impact categories assessed, many of the
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Executive Summary
trade-offs associated with greater nutrient reductions could be significantly reduced if the
WWTP were to use an electrical grid with r with lower emissions and/or to use recovered
resources (e.g., biogas) to generate on-site energy, reducing the need for purchased electricity.
Overall, two key findings emerged from this analysis. First, clear trade-offs in cost and
potential environmental impact were demonstrated between treatment level configurations. This
suggests that careful consideration should be given to the benefits from lower nutrient levels
compared to the potential environmental and economic costs associated with treatment processes
used to achieve those levels. Combining outcomes into metrics such as nutrients removed per
dollar or per unit energy may help to identify configurations that strike an efficient balance
between these objectives. For example, this analysis found that electricity per unit of total N and
P equivalents removed remained consistent from Level 2 through Level 4 but was 2-3 times
higher for Level 5 configurations. Second, this analysis demonstrated the value of a life cycle
approach to assessing costs and benefits. For example, considering trace pollutants from a life
cycle perspective illuminated that the benefits of increased trace pollutant removal from effluent
could be outweighed by trace pollutant emissions from materials and energy usage for the Level
5 configuration, an insight that would not have been gained by analyzing on-site WWTP
processes alone. In summary, considering multiple economic, social, and environmental costs
and benefits from a life cycle perspective can provide critical insights for informed decision-
making about wastewater treatment technologies.
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Foreword
Foreword
The objective of this study is to assess a series of wastewater treatment system
configurations designed to reduce the nutrient content of effluent from municipal wastewater
treatment facilities. The combination of life cycle assessment (LCA) and life cycle cost analyses
(LCCA) provides a full picture of costs, both quantitative and qualitative, for the various
wastewater treatment configurations evaluated. This technical report presents the results of the
study. It does not discuss the policy implications of the analysis, nor does it discuss the EPA's
policy on nutrient pollution, the development of nutrient criteria, approaches for addressing the
problem, nor the full suite of benefits from the different treatment configurations that can be
realized.
This report complements and supplements the EPA's May 2015 publication, A
Compilation of Cost Data Associated with the Impacts and Control of Nutrient Pollution
(https://www.epa.gov/nutrient-policv-data/compilation-cost-data-associated-impacts-and-
control-nutrient-pollution), which provides the public with information to assist stakeholders and
decision-makers in addressing cultural eutrophication.
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Acronyms and Abbreviations
Acronyms and Abbreviations
A20
Anaerobi c/ Anoxi c/Oxi c
AS
Activated sludge
BNR
Biological nutrient removal
BOD
Biochemical oxygen demand
CAPDETWorks™
Computer Assisted Procedure for the Design and Evaluation of
Wastewater Treatment Systems
CBOD
Carbonaceous biochemical oxygen demand
CEC
Contaminants of emerging concern
CED
Cumulative Energy Demand
CHP
Combined heat and power
COD
Chemical oxygen demand
DBP
Disinfection byproduct
DBPFP
Disinfection byproduct formation potential
DQI
Data quality indicator
EDC
Endocrine disrupting chemicals
EF
Emission factor
eGRID
Emissions & Generation Resource Integrated Database
EPA
Environmental Protection Agency (U.S.)
ERG
Eastern Research Group, Inc.
FP
Formation potential
GHG
Greenhouse gas
GT
Gravity thickener
GWP
Global warming potential
HAA
Haloacetic acid
HAB
Harmful algal blooms
HAN
Haloacetonitrile
HHV
High heating value
ICE
Internal combustion engine
ISO
International Standardization Organization
LCA
Life cycle assessment
LCCA
Life cycle cost analysis
LCI
Life cycle inventory
LCIA
Life cycle impact assessment
MBR
Membrane bioreactor
MCF
Methane conversion factor
N
Nitrogen
NNC
Numeric nutrient criteria
NOM
Natural organic matter
NPCC
NorthEast Power Coordinating Council
ORD
Office of Research and Development (U.S. EPA)
P
Phosphorus
PM
Particulate matter
PPCP
Pharmaceuticals and personal care products
PPI
Producer's price indices
RO
Reverse osmosis
THM
Trihalomethanes
TKN
Total Kjeldahl nitrogen
TN
Total nitrogen
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Acronyms and Abbreviations
TP
Total phosphorus
TRACI
Tool for the Reduction and Assessment of Chemical and Environmental
Impacts
UF
Ultrafiltration
UIC
Underground injection control
UNFCCC
United Nations Framework Convention on Climate Change
US LCI
United States Life Cycle Inventory Database
VFA
Volatile fatty acids
WWT
Wastewater treatment
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A cknowledgements
Acknowledgements
This work was overseen by members of an EPA working group led by Mario Sengco
(Office of Water, Office of Science and Technology), with valuable input from Tony Tripp
(Office of Water, Office of Science and Technology), Phil Zahreddine (Office of Water, Office
of Wastewater Management), and colleagues in the Office of Research and Development,
National Risk Management Research Laboratory, including Cissy Ma, David Meyer, Jane Bare,
Andrew Henderson and Xiaobo Xue.
This work was performed under a contract with Eastern Research Group (ERG). The
technical workgroup consisted of Sarah Cashman, Sam Arden, Ben Morelli, Jessica Gray,
Deborah Bartram and Debra Falatko.
The EPA expresses its gratitude to two external reviewers who provided vital feedback
on the preliminary engineering analysis and life cycle assessment.
EP-C-I6-QQ3; WA 2^37
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Table of Contents
TABLE OF CONTENTS
Page
1. Goal and Scope Definition 1-1
1.1 Introduction and Objective 1-1
1.2 Scope 1-3
1.2.1 Wastewater Treatment Configurations 1-3
1.2.2 Functional Unit 1-6
1.2.3 System Definition and Boundaries 1-9
1.2.4 System Descriptions of Wastewater Treatment Configurations 1-10
1.2.5 Metrics and Life Cycle Impact Assessment 1-27
2. Trace Pollutant Removal Performance Characterization 2-1
2.1 Heavy Metal s 2-1
2.2 Toxic Organic Pollutants 2-5
2.3 Disinfection Byproducts 2-8
3. Life Cycle Cost Analysis Methodology 3-1
3.1 Data Sources 3-1
3.2 Engineering Cost Estimation 3-3
3.2.1 Dollar Basis 3-4
3.2.2 Unit Construction and Labor Costs 3-5
3.2.3 Unit Process Costs 3-6
3.3 LCCA 3-15
3.3.1 Total Capital and Total Annual 3-15
3.3.2 Net Present Value 3-20
3.4 Data Quality 3-22
4. LCA Methodology 4-1
4.1 Life Cycle Inventory Structure 4-1
4.2 LCI Background Data Sources 4-3
4.3 LCI Foreground Data Sources 4-4
4.3.1 Foreground Unit Processes Calculations 4-5
4.3.2 Process Air Emissions Estimation Methodologies 4-7
4.4 LCI Limitations 4-7
4.5 LCA Modeling Procedure 4-8
4.6 Life Cycle Impact Assessment (LCIA) 4-9
4.6.1 Eutrophication Potential 4-10
4.6.2 Cumulative Energy Demand 4-12
4.6.3 Global Warming Potential 4-12
4.6.4 Acidification Potential 4-13
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Table of Contents
TABLE OF CONTENTS (Continued)
Page
4.6.5 Fossil Depletion 4-14
4.6.6 Smog Formation Potential 4-14
4.6.7 Human Health—Particulate Matter Formation Potential 4-15
4.6.8 Ozone Depletion Potential 4-15
4.6.9 Water Depletion 4-16
4.6.10 Human Health—Cancer Potential 4-17
4.6.11 Human Health—Noncancer Potential 4-18
4.6.12 Ecotoxicity Potential 4-19
4.6.13 Normalization 4-20
4.6.14 LCIA Limitations 4-20
4.6.15 Interpreting LCIA Results Differences 4-21
5. Life Cycle Cost Baseline Results 5-1
5.1 Total Capital and Total Annual Cost Results 5-2
5.1.1 Total Capital Costs 5-2
5.1.2 Total Annual Costs 5-4
5.2 Net Present Value Cost Results 5-7
5.3 Cost Results Quality Discussion 5-8
6. Life Cycle Impact Assessment Baseline Results by Treatment Group 6-1
6.1 Eutrophication Potential 6-1
6.2 Cumulative Energy Demand 6-4
6.3 Global Warming Potential 6-6
6.4 Acidification Potential 6-8
6.5 Fossil Depletion 6-9
6.6 Smog Formation Potential 6-10
6.7 Human Health-Particulate Matter Formation Potential 6-11
6.8 Ozone Depletion Potential 6-12
6.9 Water Depletion 6-13
7. Toxicity LCIA Results 7-1
7.1 Human Health-Cancer Potential 7-1
7.2 Human Health-Noncancer Potential 7-3
7.3 Ecotoxicity Potential 7-4
8. Summary Baseline Results 8-1
8.1 Baseline Results Summary 8-1
8.2 Normalized Baseline Results 8-5
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Table of Contents
TABLE OF CONTENTS (Continued)
Page
9. Sensitivity Analysis 9-1
9.1 Overview 9-1
9.2 Interest and Discount Rates 9-1
9.3 Global Warming Potential 9-3
9.4 Electrical Grid Mix 9-5
9.5 Biogas Energy Recovery 9-9
9.5.1 System Description 9-9
9.5.2 Biogas Sensitivity LCIA Results 9-11
9.5.3 Biogas Sensitivity LCCA 9-15
9.6 Retrofit Case Study 9-16
10. Conclusions 10-1
11. References 11-1
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Appendices
APPENDICES
Appendix A: Selection of Wastewater Treatment Configurations
Appendix B: Detailed Characterization of Heavy Metals Behavior in Study Treatment
Configurations
Appendix C: Detailed Characterization of Toxic Organics Behavior in Study Treatment
Configurations
Appendix D: Detailed Characterization of Disinfection Byproduct Formation Potential in Study
Treatment Configurations
Appendix E: Detailed Cost Methodology
Appendix F: Detailed Air Emissions Methodology
Appendix G: Example LCI Data Calculations
Appendix H: Summary LCI Result
Appendix I: Cost Results by Unit Process
Appendix J: LCIA Results by Unit Process
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List of Tables
LIST OF TABLES
Page
Table 1-1. Target Effluent Nutrient Concentrations by Level 1-4
Table 1-2. Wastewater Treatment Configurations Selected for this Study 1-5
Table 1-3. Composition of Influent Wastewater Considered in this Study 1-6
Table 1-4. Effluent Composition for the Nine Wastewater Treatment Configurations
(mg/I.) 1-8
Table 1-5. Study Treatment Configuration Characteristics 1-17
Table 1-6. Metrics Included in the LCA and LCCA Results 1-27
Table 2-1. Summary of Literature and Case Study Metal Influent Concentrations and
Regulatory Effluent Concentrations 2-3
Table 2-2. Summary of Estimated Metal Removal Efficiencies21 2-4
Table 2-3. Occurrence of the Selected Toxic Organic Compounds in WWTP Influent 2-6
Table 2-4. Summary of Cumulative Toxic Organics Degradation and Removal Efficiency
in Study Treatment Configurations21 2-8
Table 2-5. Summary of Study Disinfection Byproducts 2-9
Table 2-6. DBPFP Model Results for Study Treatment Configurations 2-11
Table 3-1. Unit Construction and Labor Costs 3-6
Table 3-2. Direct Cost Factors 3-17
Table 3-3. Indirect Cost Factors 3-19
Table 3-4. Cost Data Quality Criteria 3-22
Table 4-1. Background Unit Process Data Sources 4-3
Table 4-2. U.S. Average Electrical Grid Mix 4-4
Table 4-3. Foreground Unit Processes Included in Each Wastewater Treatment
Configuration 4-5
Table 4-4. Main Pollutants Contributing to Eutrophication Potential Impacts (kg N eq/ kg
Pollutant) 4-11
Table 4-5. Main Energy Resources Contributing to Cumulative Energy Demand 4-12
Table 4-6. Main GHG Emissions Contributing to Global Warming Potential Impacts (kg
CO; eq/kg GHG) 4-12
Table 4-7. Main Pollutants Contributing to Acidification Potential Impacts (kg SO2 eq/kg
Pollutant) 4-13
Table 4-8. Main Fossil Fuel Resource Contributing to Fossil Depletion (kg oil eq/kg
Fossil Fuel Resource) 4-14
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List of Tables
LIST OF TABLES (Continued)
Page
Table 4-9. Main Pollutants Contributing to Smog Formation Impacts (kg O3 eq/kg
Pollutant) 4-14
Table 4-10. Main Pollutants Contributing to Human Health-Particulate Matter Formation
Potential (kgPM2.5 eq/kg Pollutant) 4-15
Table 4-11. Main Pollutants Contributing to Ozone Depletion Potential Impacts (kg
CFC11 eq/kg Pollutant) 4-16
Table 4-12. Main Water Flows Contributing to Water Depletion 4-16
Table 4-13. Main Pollutants Contributing to Human Health - Cancer Potential Impacts
(CTUh/kg Pollutant) 4-17
Table 4-14. Main Pollutants Contributing to Human Health—Noncancer Potential
Impacts (CTUh/kg Pollutant) 4-18
Table 4-15. Main Pollutants Contributing to Ecotoxicity Potential Impacts (CTUe [PAF
m3. day /kg Pollutant]) 4-20
Table 5-1. Total Costs by Wastewater Treatment Configuration 5-1
Table 5-2. Unit Processes by Treatment Group 5-1
Table 5-3. Total Costs Compared to Falk et al., 2011 5-9
Table 6-1. Nutrient Discharges by Wastewater Treatment Configuration 6-2
Table 8-1. Summary LCIA and Cost Results for Nine Wastewater Treatment
Configurations (per m3 wastewater treated) 8-3
Table 8-2. 2008 U.S. Normalization Factors and Per Capita Annual Impacts 8-5
Table 8-3. Estimated Annual Contribution of Municipal Wastewater Treatment Per
Capita Impact in Seven Impact Categories 8-7
Table 9-1. 2007 versus 2013 IPCC GWPs 9-4
Table 9-2. Percent Change in GWP Impact due to GWP Factor Selection 9-5
Table 9-3. NPCC eGRID Regional versus U.S. Average Electrical Grid Mix 9-5
Table 9-4. Electrical Grid Sensitivity Analysis, U.S. Average versus NPCC Electrical
Grid (per m3 wastewater treated) 9-8
Table 9-5. Biogas Processing and CHP System Specifications for Nine Treatment System
Configurations 9-10
Table 9-6. Summary of Comparative Impact Assessment Results for the Base Case and
CHP Energy Recovery Sensitivity 9-14
Table 9-7. Summary of Biogas LCCA Costs (million 2014 $s) 9-15
Table 9-8. Greenfield and Level 2-1 to 4 Retrofit Total Costs 9-20
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List of Tables
LIST OF TABLES (Continued)
Page
Table 9-9. Summary LCIA and Cost Results for Nine Greenfield Wastewater Treatment
Configurations and the Level 2 Retrofit Case Study (per m3 wastewater
treated) 9-23
Table 10-1. Nutrient Removal Electricity Performance Metrics 10-1
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List of Figures
LIST OF FIGURES
Page
Figure 1-1. Generalized Study System Boundary 1-9
Figure 1-2. Level 1: Conventional Plug Flow Activated Sludge Wastewater Treatment
Configuration 1-18
Figure 1-3. Level 2-1: Anaerobic/Anoxic/Oxic Wastewater Treatment Configuration 1-19
Figure 1-4. Level 2-2: Activated Sludge, 3-Sludge System Wastewater Treatment
Configuration 1-20
Figure 1-5. Level 3-1: 5-Stage Bardenpho System Wastewater Treatment Configuration 1-21
Figure 1-6. Level 3-2: Modified University of Cape Town Process Wastewater Treatment
Configuration 1-22
Figure 1-7. Level 4-1: 5-Stage Bardenpho System with Denitrification Filter Wastewater
Treatment Configuration 1-23
Figure 1-8. Level 4-2: 4-Stage Bardenpho Membrane Bioreactor System Wastewater
Treatment Configuration 1-24
Figure 1-9. Level 5-1: 5-Stage Bardenpho with Sidestream Reverse Osmosis Wastewater
Treatment Configuration 1-25
Figure 1-10. Level 5-2: 5-Stage Bardenpho Membrane Bioreactor with Sidestream
Reverse Osmosis Wastewater Treatment Configuration 1-26
Figure 3-1. RSMeans Historical Cost Indexes 3-5
Figure 4-1. Subset of LCA Model Structure with Example Unit Process Inputs and
Outputs 4-2
Figure 5-1. Total Capital Costs by Aggregated Treatment Group 5-4
Figure 5-2. Annual Costs by Wastewater Treatment Configuration 5-5
Figure 5-3. Annual Costs by Aggregated Treatment Group 5-7
Figure 5-4. Net Present Value by Wastewater Treatment Configuration 5-8
Figure 6-1. Eutrophication Potential Results by Treatment Group 6-3
Figure 6-2. Eutrophi cation Potential Results by Process Contribution 6-4
Figure 6-3. Cumulative Energy Demand Results by Treatment Group 6-5
Figure 6-4. Cumulative Energy Demand Results by Process Contribution 6-6
Figure 6-5. Global Warming Potential Results by Treatment Group 6-7
Figure 6-6. Global Warming Potential Results by Process Contribution 6-8
Figure 6-7. Acidification Potential Results by Treatment Group 6-9
Figure 6-8. Fossil Depletion Results by Treatment Group 6-10
Figure 6-9. Smog Formation Potential Results by Treatment Group 6-11
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List of Figures
Figure 6-10. Human Health Particulate Matter Formation Potential Results by Treatment
Group 6-12
Figure 6-11. Ozone Depletion Potential Results by Treatment Group 6-13
Figure 6-12. Water Depletion Results by Treatment Group 6-14
Figure 7-1. Contribution Analysis of Cumulative Toxicity Impacts 7-2
Figure 7-2. Human Health - Cancer Potential Results by Treatment Group (CTUh/m3
wastewater treated) 7-2
Figure 7-3. Human Health - Noncancer Potential Results by Treatment Group (CTUh/m3
wastewater treated) 7-4
Figure 7-4. Ecotoxicity Potential Results by Treatment Group (CTUe/m3 wastewater
treated) 7-5
Figure 8-1. Relative LCIA and Cost Results for Nine Wastewater Treatment
Configurations 8-2
Figure 8-2. Illustrative Comparison of LCIA and Cost Results for Three Wastewater
Treatment Configurations 8-4
Figure 9-1. 3% versus 5% Interest Rate Total Construction Sensitivity Analysis Results 9-2
Figure 9-2. 3% versus 5% Interest and Discount Rate Net Present Value Sensitivity
Analysis Results 9-3
Figure 9-3. 2007 versus 2013 IPCC GWP Sensitivity Analysis Results 9-4
Figure 9-4. Electrical Grid Mix Sensitivity Analysis Results 9-7
Figure 9-5. System Diagram of Biogas Processing and CHP System 9-9
Figure 9-6. Global Warming Potential by Treatment Group for Base Results and the CHP
Energy Recovery Sensitivity 9-12
Figure 9-7. Cumulative Energy Demand by Treatment Group for Base Results and the
CHP Energy Recovery Sensitivity 9-13
Figure 9-8. Biogas Case Study Net Present Value Comparison 9-16
Figure 9-9. Level 2-1: Anaerobic/Anoxic/Oxic Wastewater Treatment Configuration
(Baseline for Retrofit) 9-18
Figure 9-10. Level 2-1 to 4 Retrofit: Anaerobic/Anoxic/Oxic with Chemical Phosphorus
Removal and Denitrification Filter Wastewater Treatment Retrofit
Configuration 9-19
Figure 9-11. Level 2-1 A20 Baseline and Retrofit Total Capital Costs by Aggregated
Treatment Group 9-20
Figure 9-12. Level 2-1 A20 Baseline and Retrofit Total Annual Costs by Annual Cost
Category 9-21
Figure 9-13. Relative LCIA Results for Nine Greenfield Wastewater Treatment
Configurations and the Level 2 Retrofit Case Study 9-22
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Section 1: Goal and Scope Definition
1. Goal and Scope Definition
1.1 Introduction and Objective
Cultural eutrophication of waterbodies across the United States is one of the most
pervasive environmental issues facing the country today. Whether in lakes or reservoirs, rivers or
streams, estuaries or marine coastal waters, the human health, environmental, and economic
impacts from excessive amounts of nitrogen (N) and phosphorus (P) continue to rise year after
year. Communities struggle with harmful algal blooms (HABs) that produce toxins which can
sicken people and pets, contaminate food and drinking water sources, destroy aquatic life, and
disrupt the balance of natural ecosystems. HABs can raise the cost of drinking water treatment,
depress property values, close beaches and fishing areas, and negatively affect the health and
livelihood of many Americans (U.S. EPA, 2015a). Global climate change is only expected to
exacerbate eutrophi cation even as Federal, state, and local governments struggle to address the
sources of nutrient pollution (USGCRP, 2015).
In partnership with states, tribes, and other Federal agencies, the U.S. Environmental
Protection Agency (EPA) has led the effort to address nutrient pollution by assisting states in
prioritizing waters, providing scientific and technical assistance in the development of water
quality standards for total nitrogen (TN) and total phosphorus (TP), and helping to guide
implementation of nutrient criteria in waterbody assessments, including the development of total
maximum daily loads for impaired waters and the inclusion of water-quality based effluent limits
for point source dischargers.
In many watersheds, municipal and industrial wastewater treatment plants (WWTPs) can
be major point sources of nutrients. Removal of TN and TP can vary significantly depending on
the raw wastewater characteristics and the treatment technologies used at each WWTP. Recent
efforts by states and the EPA to derive numeric nutrient criteria (NNC) that will protect the
designated uses under the Clean Water Act reveal limits that clearly push the boundaries of
treatment technologies currently in place for most facilities in the United States. Operators and
other stakeholders have expressed concern that there may be potentially significant
environmental and health implications and economic impacts associated with pushing those
boundaries, given it can lead to greater use of chemicals, treatment residuals disposal, increased
energy demands, and greater release of greenhouse gases. Studies in other countries also suggest
a point of diminishing returns where the economic and environmental consequences may begin
to outweigh the benefits of certain advanced treatment technologies (e.g., Foley et al., 2010).
Such issues, which encompass economic, environmental, and social costs, are at the center of
sustainability evaluations, and can be assessed using holistic, systematic approaches such as life
cycle assessment (LCA) and life cycle cost analysis (LCCA).
LCA is a widely accepted technique to assess the environmental aspects and potential
impacts associated with individual products, processes, or services. It provides a "cradle-to-
grave" analysis of environmental impacts and benefits that can better assist in selecting the most
environmentally preferable choice among the various options. The steps for conducting an LCA
include (1) identifying goal and scope, (2) compiling a life cycle inventory (LCI) of relevant
energy and material inputs and environmental releases, (3) evaluating the potential
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Section 1: Goal and Scope Definition
environmental impacts associated with identified inputs and releases, and (4) interpreting the
results to help individuals make a more informed decision.
LCCA is a complementary process to LCA for evaluating the total economic costs of an
asset by analyzing initial costs and discounted future expenditures over the life cycle of an asset
(Varnier, 2004). It is used to evaluate differences in cost and timing of those costs between
alternative projects. The LCCA conducted in this study is not "cradle-to-grave", but rather
considers only costs incurred by the facility for establishing a new WWTP (i.e., greenfield
project1). A retrofit case study was performed and described later in this report.
The objective of this study is to assess a series of wastewater treatment system
configurations (hereafter referred to as "wastewater treatment configurations") designed to
reduce the nutrient content of effluent from municipal WWTPs. The assessment considers
treatment costs as well as human health and ecosystem impacts from a life cycle perspective. The
combination of LCA and LCCA provides a full picture of costs, both quantitative and qualitative,
for the various wastewater treatment configurations evaluated. This report uses the term
wastewater treatment plant, or WWTP, while recognizing that an effort is underway to transition
to a new term: "water resource recovery facility". The use of WWTP was selected only as a
reflection of historical usage and is not intended to convey preference.
This study compares cost, human health, and ecosystem metrics associated with nine
distinct wastewater treatment configurations to provide context for understanding the outcomes
from an environmental, economic, and social/societal perspective. The nine wastewater
treatment configurations fall into one of five different levels of nutrient reductions, as defined in
Table 1-1. Level 1 is a baseline system consisting of a standard secondary treatment
configuration with no specific nutrient removal target. The other four levels considered here
specify nutrient removal targets with increasing stringency. The wastewater treatment
configurations selected for assessment include two alternative configurations for each of the
nutrient reduction levels 2 through 5. These configurations were selected because they generally
represent configurations commonly used to achieve the specified nutrient performance levels.
These configurations were also selected to provide contrast in factors such as the biological
processes used, capital costs, operating costs, energy requirements, and sludge generation.
While effluent nutrient concentrations are the main driver of the treatment configuration
upgrades analyzed by this study, there is also growing concern over the impacts associated with
trace pollutants (Choubert et al., 201 la; Martin Ruel et al., 2012; Montes-Grajales et al., 2017).
Trace pollutants are a broad class of compounds that are generally toxic to humans or the aquatic
environment even at very low concentrations (U.S. EPA, 2015). Although the list of individual
1 Greenfield areas are normally undeveloped areas highly recommended for new construction. The benefits of
greenfield construction relate to pristine pieces of land with little to no contamination that contain no structures in
the premises. The most beneficial advantage is that there is no cost related to environmental remediation and is
ready to start building right away. The most important drawback is that greenfield are usually located outside city
centers that might require additional infrastructure upgrades but those are offset by more accessible land costs.
Another advantage is that they offer larger pieces of real estate ideally for future expansion and their zoning
classification is easier to be changed or adjusted as required. Keep in mind that greenfield usually require
deforestation and could affect environmental sensitive areas including the habitat of endangered species.
KP-C-16-003; WA 2^37
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Section 1: Goal and Scope Definition
compounds is continually evolving, the class generally includes pharmaceuticals and personal
care products (PPCPs), toxic organics, disinfection byproducts (DBPs) and heavy metals.
Importantly, as the prevalence of trace pollutants in modern waste streams is increasing (Ellis,
2008; U.S. EPA, 2015; Ebele et al., 2017), with varying levels of persistence in the environment,
they are becoming an important component of modern waste stream management. Many of these
pollutants already factor into standard LCA inventories, where emissions of upstream processes
are accounted for and contribute to human and environmental health impact categories.
However, very little work has been done to incorporate the effects of their direct management at
WWTPs, especially in the context of LCA. Such an assessment would provide valuable
information as to the full benefits afforded by advanced treatment technologies, as many of the
same processes that are effective for nutrient removal are also effective at trace pollutant
removal. Preliminary studies have been conducted on certain pollutant groups such as PPCPs and
other toxic organics (Montes-Grajales et al., 2017; Rahman et al., 2018) though they have
omitted important pollutant groups such as heavy metals and DBPs. This study, therefore, looked
in greater detail at a more encompassing list of trace pollutants, including heavy metals, toxic
organics and DBPs, to provide a more comprehensive description of the full costs and benefits
afforded by advanced nutrient removal technologies.
The metrics used in this assessment are cost and a suite of LCA-related impacts. The
LCA-related impacts include eutrophication, global warming, particulate matter formation, smog
formation, acidification, and ozone depletion based on the Tool for Reduction and Assessment of
Chemicals and other Environmental Impacts (TRACI) 2.1 life cycle impact assessment (LCIA)
method; water use and fossil energy use based on the ReCiPe2 method; human and ecosystem
toxicity impacts based on the USEtox™ methodology version 2.02; and cumulative energy
demand (Bare, 2012; Goedkoop et al., 2009; Huijbregts et al., 2010). These metrics are discussed
in detail in Section 1.2.5 and Section 4.6. The trace pollutant removal analysis is integrated with
the toxicity impact category results.
1.2 Scope
This study design follows the guidelines for LCA provided by ISO 14040/14044 (ISO,
2006a, b). The following subsections describe the scope of the study based on the wastewater
treatment configurations selected and the functional unit used for comparison, as well as the
system boundaries, LCIA methods, and datasets used in this study.
1.2.1 Wastewater Treatment Configurations
This study compares nine alternative wastewater treatment configurations that achieve
varying levels of nutrient removal, including a baseline wastewater treatment configuration that
is not specifically designed to remove nutrients and eight wastewater treatment configurations
that are designed to achieve varying advanced levels of nitrogen and phosphorus removal. The
target effluent concentrations for TN and TP for each of the performance levels are presented in
Table 1-1, and are based on performance levels analyzed in a study by Falk and colleagues
(2011). The wastewater treatment configurations selected for this study are presented in Table
2 The name of this method "ReCiPe" is derived from two factors. First, the method provides a recipe to calculate life
cycle impact categories. Second, the acronym represents the initials of institutes that were the main contributors:
RIVM and Radboud University, CML, and PRe (Goedkoop et al., 2008).
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Section 1: Goal and Scope Definition
1-2 and described further in Section 1.2.4 and Appendix A. Table 1-2 also lists the abbreviated
name used for each wastewater treatment configuration throughout this study. Selected
configurations generally represent those most commonly used to achieve the desired
performance levels for nutrient requirements and provide contrast in biological processes, capital
and/or annual costs, or other factors such as energy requirements and sludge generation. The
most common reasons wastewater treatment configurations were not selected include: 1) they are
unique retrofits and otherwise not commonly used, 2) they are very similar to another selected
technology, or 3) they exhibit a wide range of performance, which raises uncertainty as to the
reliability with which the process can achieve a specific performance level. Ultimately, two
wastewater treatment configurations were selected for each of Levels 2 through 5 to illustrate the
range of costs and environmental impacts associated with varying levels of treatment
performance. More detail on the system configuration selection process is included in Appendix
A.
Table 1-1. Target Effluent Nutrient Concentrations by Level
1 .evel
Total .Nitrogen, mg/l.
Total Phosphorus. mg/L
1
a
a
2
8
l
3
4-8
0.1-0.3
4
3
0.1
5
<2
<0.02
a - No target effluent concentration specified.
KP-C-16-003; WA 2^37
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Section 1—Goal and Scope Definition
Table 1-2. Wastewater Treatment Configurations Selected for this Study
I-nil Nil 1110 '
I'd'Coi'iiiiincc
l.e\cl
\l)hio\ iiiiod
N;i mo
Phosphorus
Pivcipiliiliun
l-Vrnu'iiU'r
Siind l ilkr
Ik'iiilriliciilion
Killer
I llr;i-Hllr;ilioii
Uc\ or so
Osmosis
Conventional Plug
Flow Activated
Sludge
1
Level 1, AS
Anaerobic/
Anoxic/Oxic
2
Level 2-1,
A20
Activated Sludge,
3-Sludge System
2
Level 2-2, AS3
V
5-Stage Bardenpho
3
Level 3-1, B5
V
V
V
Modified
University of Cape
Town Process
3
Level 3-2,
MUCT
V
V
V
5-Stage Bardenpho
with
Denitrification
Filter
4
Level 4-1,
B5/Denit
V
V
V
V
4-Stage Bardenpho
Membrane
Bioreactor
4
Level 4-2,
MBR
V
5-Stage Bardenpho
with Sidestream
Reverse Osmosis
5
Level 5-1,
B5/R0
V
V
V
10% b
90% b
90% b
5-Stage Bardenpho
Membrane
Bioreactor with
Sidestream
Reverse Osmosis
5
Level 5-2,
MBR/RO
V
V
85% b
•J Indicates technology is used in wastewater treatment configuration,
a - Refer to Section 1.2.4 for the system descriptions.
b - Percentages describe the relative flow of wastewater entering these processes at the WWTP.
KP-C-16-003; WA 2^37
1-5
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Section 1—Goal and Scope Definition
1.2.2 Functional Unit
A functional unit provides the basis for comparing results in an LCA. The key
consideration in selecting a functional unit is to ensure the wastewater treatment configurations
are compared on the basis of equivalent performance. In other words, an appropriate functional
unit allows for an apples-to-apples comparison. The functional unit for this study is the treatment
of a cubic meter of municipal wastewater with the composition described in Table 1-3. The pH
of the reference wastewater is 7.6 and the temperature averages are 23°C summer and 10°C
winter.
The study evaluated theoretical wastewater treatment configurations with an average flow
rate of 10 million gallons per day (MGD) and a maximum flow rate of 20 MGD3. The study
results do not represent a specific, existing WWTP. As discussed in Section 3 the operational
calculations are based on a year of treatment and standardized to a cubic meter basis using the
total volume of water treated in the year. Infrastructure requirements are amortized over
individual lifetimes associated with the equipment or buildings. Section 3 provides the lifetimes
modeled for all infrastructure components captured in the study. While the WWTP infrastructure
requirements are modeled, plant decommissioning is outside of the scope of the study.
It is important to note that the composition of effluent resulting from the wastewater
treatment configurations is not part of the definition of the functional unit. Rather the level of
treatment performance is a key differentiator of the configurations. Differences in effluent
composition are captured in the estimation of impacts associated with the effluent discharges for
each system. Effluent quality values for standard water quality parameters for the nine
wastewater treatment configurations are depicted in Table 1-4. The effluent quality in Table 1-4
is based on the CAPDETWorks™ output and may vary from actual WWTP effluent for the same
wastewater treatment configuration. However, these wastewater treatment configurations were
chosen based on actual effluent nutrient concentrations from literature as discussed in Appendix
A. Effluent quality values for trace pollutants, which include toxic organics, DBPs and heavy
metals, are discussed in further detail in Section 2.
Table 1-3. Composition of Influent Wastewater Considered in this Study
C liiirncloristic
\ ill III'
I nil
Reference! s)
Suspended Solids
220
mg/L
1, 2, 3, 4
Volatile Solids
75
0/
/O
1, 2, 3, 4
Biological Oxygen Demand (BOD)
220
mg/L
1, 2, 3, 4
Soluble BOD
80
mg/L
2, 3,4
Chemical Oxygen Demand (COD)
500
mg/L
1, 2, 3, 4
Soluble COD
300
mg/L
2, 3,4
Total Nitrogen (TN)a
40
mg/L N
calculated
3 ERG used a 2.0 peaking factor for the study, assuming the WWTP served approximately 100,000 people (Health
Research, Inc., 2014).
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Section 1—Goal and Scope Definition
Table 1-3. Composition of Influent Wastewater Considered in this Study
Chsimclcrislic
Value
I nil
Reference! s)
Total Kjeldahl Nitrogen (TKN)b
40
mg/L N
1, 2, 3, 4
Soluble TKN
25
mg/L N
2,3
Ammonia
22
mg/L N
1,4
Nitrate
0
mg/L N
1, 2, 3, 4
Nitrite
0
mg/L N
1, 2, 3, 4
Total Phosphorus (TP)
5
mg/L P
2,3
Cations
160
mg/L
3,4
Anions
160
mg/L
3,4
Settleable Solids
10
mg/L
1,3,4
Oil and Grease
100
mg/L
1,3,4
Nondegradable Fraction of Volatile Suspended Solids (VSS)
40
0/
/O
3,4
1 Tchobanoglous and Burton, 1991;2U.S. EPA OWM, 2008b;3 ERG, 2009;4Hydromantis, 2014
a - TN is the sum of TKN, nitrate, and nitrite.
b - TKN is the sum of ammonia, organic nitrogen, and reduced nitrogen.
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Section 1—Goal and Scope Definition
Table 1-4. Effluent Composition for the Nine Wastewater Treatment Configurations (mg/L)
(onsliliienl
I.CM'I 1,
AS
Le\el 2-1.
A2()
Le\el 2-2.
A S3
1 .e\ el 3-1.
U5
l.e\el 3-2.
Ml C I
l.e\el 4-1.
Ii5/I)eni(
l.e\el 4-2.
MUR
l.e\el 5-1,
U5/RO
l.e\el 5-2.
Mlik/RO
Suspended Solids
2u
2u
2u
8.0
8.0
8.0
y.u
1.3
l.y
BOD
7.7
4.7
3.1
2.3
2.3
7.0
3.1
1.2
0.62
Soluble BOD
3.9
2.3
1.5
2.3
2.3
7.0
2.1
1.2
0.45
COD
28
25
8.9
3.5
3.5
11
13
1.8
2.6
Soluble COD
5.8
3.5
2.3
3.5
3.5
11
3.21
1.8
0.70
Total Phosphorus
4.9
0.28
1.0
0.20
0.20
0.10
0.10
0.02
0.02
Total Nitrogen
30
8.0
7.8
6.0
6.0
3.0
3.0
0.73
2.0
TKN
30
1.9
2.1
0.52
0.52
0.52
1.0
0.15
0.20
Soluble TKN
29
0.52
1.6
0.52
0.52
0.52
0.42
0.09
0.08
Ammonia
15
0.52
0
0.52
0.52
0.52
0.42
0.09
0.08
Nitrate
0
6.1
5.7
5.5
5.5
2.4
2.0
0.63
1.8
Organic Nitrogen
15
1.4
2.1
0
0
0
0.58
0.06
0.12
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1-8
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Section 1: Goal and Scope Definition
1.2.3 System Definition and Boundaries
This section describes general aspects of each wastewater treatment configuration that are
included in the LCA system boundary. The boundary for processes included in the assessment of
each of the wastewater treatment configurations selected for evaluation includes all onsite
wastewater and sludge treatment processes from the municipal WWTP headworks through final
discharge of the treated effluent and disposal of sludge and other wastes. Off-site costs and
environmental impacts associated with release of the effluent to the receiving stream, sludge
transport and disposal, and for facilities with reverse osmosis (RO) units, brine disposal into
onsite underground injection control (UIC) wells are also considered. The system boundary
includes all relevant details of the wastewater treatment processes, environmental releases from
each process, and the supply chains associated with the inputs to each process. Chemicals
associated with periodic cleaning of equipment (e.g., membranes) are within the system
boundary. Production of concrete, excavation activities, building materials, and a limited
quantity of steel are included as infrastructure materials in the LCA. Pumps, in-unit mechanical
systems, and electronics are excluded from the LCA study boundary due to lack of detailed
information, although these types of equipment are included in the LCCA. The LCCA also
includes costs for engineering and professional services that are not part of the LCA. A
simplified system diagram is presented in Figure 1-1, which depicts the main materials and
emission sources included in the model.
Disposal of Plant
i Engineering &
| Sewage Collection |
Electrical &
Infrastructure
| Professional Services
System
Mechanical Equipment j
Figure 1-1. Generalized Study System Boundary
EP-C'-16-003: WA 2-37
1-9
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Section 1: Goal and Scope Definition
The four orange boxes in Figure 1-1 comprise the foreground unit processes that make up
the wastewater treatment configuration at each WWTP. Electricity generation, chemical
production, material extraction and manufacturing, and disposal processes are considered
background unit processes. Disposal processes include landfilling of treated sludge and
underground injection of brine solution. Background processes are still within the system
boundary and are quantified within the analysis, although they exist beyond the physical
boundaries of the wastewater treatment plant. The exterior dotted line in Figure 1-1 represents
the system boundary considered in this LCA. The emissions to various compartments within
nature (soil, air, water) are used in the estimation of environmental impacts. Details related to the
calculation procedure and the environmental impacts included in this study are discussed in
Section 4.
Excluded from the system boundaries are production of the components that make up the
wastewater (e.g., drinking water treatment, residential organic waste, industrial wastewater
pretreatment) and the collection system, including any raw sewage pump stations. It is assumed
that these elements would be equivalent for all examined wastewater treatment configurations,
and, therefore can be excluded from the scope of the analysis.
It is important to note that some potential benefits that may be realized from level 4 and
level 5 wastewater treatment configuration are not captured in the system boundaries of this
study. For instance, it may be possible to recycle the effluent from wastewater treatment for non-
potable uses like toilet flushing or irrigation as the effluent quality may achieve non-potable
requirements. Utilization of this recycled water would avoid production of potable water
elsewhere. In an expanded system boundary, avoided production of potable water would result in
an overall credit for these higher nutrient removal wastewater treatment configurations that is not
included in this LCA study. Another potential benefit not included is the pathogen or other
microbial contaminant removal.
1.2.4 System Descriptions of Wastewater Treatment Configurations
Flow diagrams of each wastewater treatment configuration are provided in Figure 1-2
through Figure 1-10. Each of these figures provides a visual representation of the detailed unit
processes included in the relevant wastewater treatment configuration. The figures also show the
source of process greenhouse gas (GHG) emissions and the type of chemical inputs.
In each wastewater treatment configuration, wastewater is first treated by screening, grit
removal, and primary clarification. Screening removes large debris from the wastewater flow and
grit removal extracts stone, grit, and other separable debris. Debris from this stage is transported
to a landfill. In the next stage, primary clarification, solids are allowed to settle from the
wastewater and grease to float to the top. Solids are pumped out from the bottom of the tank and
scum and grease are skimmed off the top. These materials are either sent directly to a gravity
thickener (configuration levels 1, 2-1, 2-2, 4-2) or first sent to a fermenter and then to the gravity
thickener (configuration levels 3-1, 3-2, 4-1, 5-1, and 5-2) then to anaerobic digestion, and
ultimately hauled away by truck for disposal in a landfill. The assumed distance from the
wastewater treatment plant to the landfill is 25 miles one-way. In all cases, it is assumed the
biogas from anaerobic digestion is flared. A detailed emission inventory associated with biogas
flaring process is included in Appendix F. The sludge is assumed to be disposed in an average
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Section 1: Goal and Scope Definition
U.S. municipal solid waste landfill in which methane is recovered for energy. The same biogas
flaring and sludge landfilling assumptions were made for all wastewater treatment configurations
as the study focuses on differentiating factors for nutrient removal technologies rather than
options for sludge handling. Alternative treatment options for biogas is addressed later in the
sensitivity analysis later in this report (Section 9.5).
After pretreatment and primary treatment, the processes involved in each wastewater
treatment configuration varies. A description of each wastewater treatment configuration is
provided in the subsequent sections, while a summary of their relevant attributes is given in
Table 1-5.
1.2.4.1 Level 1: Conventional Plug Flow Activated Sludge (Level 1, AS)
The Level 1 configuration represents typical secondary treatment used by municipal
WWTPs in the United States. This system focuses on reducing BOD and TSS concentrations to
30 mg/L and has no specific nutrient removal targets. In the conventional plug flow activated
sludge wastewater treatment configuration, following pretreatment and primary treatment,
wastewater is sent to a plug flow activated sludge reactor for carbonaceous biochemical oxygen
demand (CBOD) removal. After plug flow activated sludge treatment, wastewater is sent to
secondary clarification where solids are allowed to settle from the wastewater. Clarified effluent
is disinfected using chlorine gas4 followed by dechlorination using sodium bisulfite to remove
residual chlorine prior to discharge. Effluent from the wastewater treatment process is discharged
to surface water. Secondary clarifier sludge is pumped out from the bottom of the clarifier. Of
this sludge, a portion is sent back to the plug flow activated sludge treatment process (return
activated sludge) and the remainder (waste activated sludge) is combined with primary sludge
before being sent to gravity thickening. Following the gravity thickener, the sludge is sent for
anaerobic digestion followed by further dewatering by centrifuge. Filtrate from the gravity
thickener, centrate from the centrifuge, and supernatant from the anaerobic digester are returned
to the influent stream at the headworks to the wastewater treatment system. Dewatered sludge is
transported to a landfill by truck.
1.2.4.2 Level 2-1: Anaerobic/Anoxic/Oxic (Level 2-1, A20)
In the Level 2-1 anaerobic/anoxic/oxic (A20) wastewater treatment configuration,
following pretreatment and primary treatment, wastewater is sent to the A20 process, which
consists of an anaerobic zone, an anoxic zone, and an oxic zone for biological phosphorus
removal, CBOD removal, nitrification (conversion of ammonia to nitrate), and denitrification
(conversion of nitrate to nitrogen gas, which is released to the atmosphere). There is an internal
recycle that returns nitrified mixed liquor from the oxic zone to the anoxic zone. A secondary
clarifier follows the A20 process where solids are allowed to settle from the wastewater.
Clarified effluent is disinfected using chlorine gas followed by dechlorination using sodium
bisulfite to remove residual chlorine prior to discharge. Effluent from the wastewater treatment
process is discharged to surface water. Secondary clarifier sludge is pumped out from the bottom
4 Chlorination using hypochlorite is more common than gaseous chlorine due to safety concerns and regulations on
the handling and storage of pressurized liquid chlorine (Tchobanoglous et al., 2014). However, CAPDETWorks™
only includes disinfection using chlorine gas (Hydromantis, 2014). As a result, ERG used chlorine gas for this study.
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Section 1: Goal and Scope Definition
of the tank with a portion returned to the influent of the A20 process (return activated sludge)
and the remainder (waste activated sludge) is combined with primary sludge before being sent to
gravity thickening. Following the gravity thickener, the sludge is sent for anaerobic digestion
followed by further dewatering by centrifuge. Filtrate from the gravity thickener, centrate from
the centrifuge, and supernatant from the anaerobic digester are returned to the influent stream at
the headworks to the wastewater treatment system. Dewatered sludge is transported to a landfill
by truck.
1.2.4.3 Level 2-2: Activated Sludge, 3-Sludge System (Level 2-2, AS3)
In the Level 2-2 activated sludge, 3-sludge wastewater treatment configuration,
wastewater undergoes pretreatment and primary treatment before entering a plug flow activated
sludge reactor for CBOD removal. Wastewater is then sent to the secondary clarifier where
solids are allowed to settle from the wastewater. Sludge is pumped out from the bottom of the
clarifier. Of this sludge, a portion is sent back to the plug flow activated sludge treatment process
(return activated sludge) and the remainder (waste activated sludge) is combined with primary
sludge before being sent to gravity thickening. Wastewater from the secondary clarifier is sent to
a suspended growth nitrification reactor to convert ammonia nitrogen to nitrate, followed by a
tertiary clarifier where solids are allowed to settle from the wastewater. A portion of the tertiary
clarifier sludge is sent back to the nitrification reactor (return activated sludge) and the remainder
(waste activated sludge) is sent to gravity thickening. Wastewater from the tertiary clarifier is
sent to a suspended growth denitrification reactor to convert nitrate to nitrogen gas. Methanol is
added immediately preceding the denitrification reactor as a supplemental carbon source. Prior to
a final clarification step, the wastewater undergoes chemical phosphorus precipitation using
aluminum salts, where solids are allowed to settle from the wastewater. A portion of the final
clarifier sludge is sent back to the denitrification reactor (return activated sludge) and the
remainder (waste activated sludge) is sent to gravity thickening. Clarified effluent is disinfected
using chlorine gas followed by dechlorination using sodium bisulfite to remove residual chlorine
prior to discharge. Effluent from the wastewater treatment process is discharged to surface water.
Following the gravity thickener, the sludge is sent for anaerobic digestion followed by further
dewatering by centrifuge. Filtrate from the gravity thickener, centrate from the centrifuge, and
supernatant from the anaerobic digester are returned to the influent stream at the headworks to
the wastewater treatment system. Dewatered sludge is transported to a landfill by truck.
1.2.4.4 Level 3-1: 5-Stage Bardenpho (Level 3-1, B5)
In the Level 3-1 5-Stage Bardenpho wastewater treatment configuration, wastewater
undergoes pretreatment and primary treatment. Sludge from the primary clarifier enters a
fermentation vessel to convert complex proteins and carbohydrates to volatile fatty acids (VFAs)
that provide an internal carbon source for biological nutrient removal. Sludge from the fermenter
is sent to gravity thickening. Primary clarifier effluent and fermenter supernatant enter a 5-stage
Bardenpho nutrient removal reactor wherein the wastewater enters an anaerobic stage before
alternating between anoxic and aerobic conditions in a total of five successive stages for
biological phosphorus removal, CBOD removal, and enhanced nitrification and denitrification.
There is an internal mixed liquor recycle that returns wastewater from the first aerobic zone to
the first anoxic zone. Following the Bardenpho reactor, part of the remaining phosphorus in the
wastewater is chemically precipitated, using aluminum salts, after which the effluent moves
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Section 1: Goal and Scope Definition
along to secondary clarification where solids are allowed to settle from the wastewater. Clarified
effluent is passed through a sand filter for tertiary solids removal prior to disinfection using
chlorine gas and dechlorination using sodium bisulfite to remove residual chlorine prior to
discharge. Effluent from the wastewater treatment process is discharged to surface water. Sludge
is removed from the bottom of the secondary clarifier. Of this sludge, a portion is sent back to
the influent of the Bardenpho reactor (return activated sludge) while the remainder (waste
activated sludge) is combined with primary sludge before being sent to gravity thickening.
Following the gravity thickener, the sludge is sent for anaerobic digestion followed by further
dewatering by centrifuge. Filtrate from the gravity thickener, centrate from the centrifuge, and
supernatant from the anaerobic digester are returned to the influent stream at the headworks to
the wastewater treatment system. Dewatered sludge is transported to a landfill by truck.
1.2.4.5 Level 3-2: Modified University of Cape Town Process (Level 3-2, MUCT)
In the Level 3-2 modified University of Cape Town process wastewater treatment
configuration, wastewater first undergoes pretreatment and primary treatment. Sludge from
primary clarification enters a fermentation vessel to convert complex proteins and carbohydrates
to VFAs that provide an internal carbon source for biological nutrient removal. Sludge from the
fermenter is sent to gravity thickening. Primary clarifier effluent and fermenter supernatant enter
a 4-stage biological nutrient removal (BNR) reactor, referred to as the modified University of
Cape Town process. Within the reactor, wastewater enters an anaerobic phase and passes
through two successive anoxic stages before a final aerobic stage for biological phosphorus
removal, CBOD removal, and enhanced nitrification and denitrification. There is an internal
mixed liquor recycle that returns wastewater from the end of the first anoxic stage to the head of
the anaerobic stage, and an additional internal recycle that returns wastewater from the aerobic
stage to the second anoxic stage. Following biological nutrient removal, phosphorus in the
wastewater is chemically precipitated, using aluminum salts, after which the effluent moves
along to secondary clarification where solids are allowed to settle from the wastewater. Clarified
effluent is passed through a sand filter for tertiary solids removal prior to disinfection using
chlorine gas and dechlorination using sodium bisulfite to remove residual chlorine prior to
discharge. Effluent from the wastewater treatment process is discharged to surface water. Sludge
is removed from the bottom of the secondary clarifier. Of this sludge, a portion is returned to the
first anoxic stage in the BNR reactor (return activated sludge) while the remainder (waste
activated sludge) is combined with primary sludge before being sent to gravity thickening.
Following the gravity thickener, the sludge is sent for anaerobic digestion followed by further
dewatering by centrifuge. Filtrate from the gravity thickener, centrate from the centrifuge, and
supernatant from the anaerobic digester are also returned to the influent stream at the headworks
to the wastewater treatment system. Dewatered sludge is transported to a landfill by truck.
1.2.4.6 Level 4-1: 5-Stage Bardenpho with Denitrification Filter (Level 4-1, B5/Denit)
In the Level 4-1 5-Stage Bardenpho with denitrification filter wastewater treatment
configuration, wastewater first undergoes pretreatment and primary treatment. Sludge from
primary clarification enters a fermentation vessel to convert complex proteins and carbohydrates
to VFAs that provide an internal carbon source for biological nutrient removal. Sludge from the
fermenter is sent to gravity thickening. Primary clarifier effluent and fermenter supernatant enter
a 5-stage Bardenpho nutrient removal reactor wherein the wastewater enters an anaerobic stage
KP-C-16-003; WA 2^37
1-13
-------
Section 1: Goal and Scope Definition
before alternating between anoxic and aerobic conditions in a total of five successive steps for
biological phosphorus removal, CBOD removal, and enhanced nitrification and denitrification.
There is an internal mixed liquor recycle that returns wastewater from the first aerobic zone to
the first anoxic zone. Following the Bardenpho reactor, phosphorus in the wastewater is
chemically precipitated, using aluminum salts, after which the effluent moves along to secondary
clarification where solids are allowed to settle from the wastewater. Clarified effluent then enters
an upflow, attached growth denitrification filter for additional nitrogen removal. Methanol is
added immediately preceding the denitrification filter as a supplemental carbon source.
Wastewater is finally passed through a sand filter for tertiary solids removal prior to disinfection
using chlorine gas and dechlorination using sodium bisulfite to remove residual chlorine prior to
discharge. Effluent from the wastewater treatment process is discharged to surface water. Sludge
is removed from the bottom of the secondary clarifier. Of this sludge, a portion is returned to the
influent of the Bardenpho reactor (return activated sludge) while the remainder (waste activated
sludge) is combined with primary sludge before being sent to gravity thickening. Following the
gravity thickener, the sludge is sent for anaerobic digestion followed by further dewatering by
centrifuge. Filtrate from the gravity thickener, centrate from the centrifuge, and supernatant from
the anaerobic digester are returned to the influent stream at the headworks to the wastewater
treatment system. Dewatered sludge is transported to a landfill by truck.
1.2.4.7 Level 4-2: 4-Stage Bardenpho Membrane Bioreactor (Level 4-2, MBR)
In the Level 4-2 4-Stage Bardenpho membrane bioreactor wastewater treatment
configuration, wastewater undergoes primary treatment before entering a 4-stage Bardenpho
nutrient removal reactor. Within the reactor wastewater alternates twice between anoxic and
aerobic stages for CBOD removal, and enhanced nitrification and denitrification. There is an
internal mixed liquor recycle that returns wastewater from the first aerobic zone to the first
anoxic zone. Methanol is added as a supplemental carbon source in the Bardenpho reactor in the
second anoxic zone. Following the Bardenpho reactor, phosphorus in the wastewater is
chemically precipitated, using aluminum salts, after which the effluent moves on for membrane
filtration to remove solids from the wastewater, generating a permeate (effluent) and reject
stream (sludge). Effluent is sent to disinfection using chlorine gas and dechlorination using
sodium bisulfite to remove residual chlorine prior to discharge. Effluent from the wastewater
treatment process is discharged to surface water. A portion of the sludge from the membrane
filter is returned to the influent to the 4-stage Bardenpho (return activated sludge) while the
remainder (waste activated sludge) is combined with primary sludge before being sent to gravity
thickening. Following the gravity thickener, the sludge is sent for anaerobic digestion followed
by further dewatering by centrifuge. Filtrate from the gravity thickener, centrate from the
centrifuge, and supernatant from the anaerobic digester are returned to the influent stream at the
headworks to the wastewater treatment system. Dewatered sludge is transported to a landfill by
truck.
1.2.4.8 Level 5-1: 5-Stage Bardenpho with Sidestream Reverse Osmosis Treatment
(Level 5-1, B5/RO)
In the Level 5-1 5-Stage Bardenpho with sidestream reverse osmosis (RO) wastewater
treatment configuration, wastewater first undergoes pretreatment and primary treatment. Sludge
from primary clarification enters a fermentation vessel to convert complex proteins and
KP-C-16-003; WA 2^37
1-14
-------
Section 1: Goal and Scope Definition
carbohydrates to VFAs that provide an internal carbon source for biological nutrient removal.
Sludge from the fermenter is sent to gravity thickening. Primary clarifier effluent and fermenter
supernatant enters a 5-stage Bardenpho nutrient removal reactor wherein the wastewater goes
through an anaerobic stage before alternating between anoxic and aerobic conditions in a total of
five successive steps for biological phosphorus removal, CBOD removal, and enhanced
nitrification and denitrification. There is an internal mixed liquor recycle that returns wastewater
from the first aerobic zone to the first anoxic zone. Following the Bardenpho reactor, additional
phosphorus in the wastewater is chemically precipitated, using aluminum salts, after which the
effluent moves along to secondary clarification where solids are allowed to settle from the
wastewater. Clarified effluent is split into two streams for further treatment. In order to meet the
designed effluent quality, ten percent of the flow enters an upflow, attached growth
denitrification filter for additional nitrogen removal, followed by a sand filter for tertiary solids
removal. Methanol is added immediately preceding the denitrification reactor as a supplemental
carbon source. The remaining 90 percent of the flow first undergoes a series of RO pre-treatment
steps, including ultrafiltration for solids removal; chlorine gas addition for biofouling control
(followed by dechlorination with sodium bisulfite due to low chlorine tolerance of the RO
membranes); and antiscalant addition for scale control. Following pretreatment, the effluent
underdoes RO treatment, generating a permeate (effluent) and reject stream (brine). Effluent
from the 10 percent and 90 percent side stream steps are then recombined for final disinfection
using chlorine gas and dechlorination using sodium bisulfite to remove residual chlorine prior to
discharge to surface water. Brine from the RO unit is disposed of by injection into an onsite
disposal well. A portion of the clarified sludge is returned to the influent of the Bardenpho
reactor (return activated sludge) while the remainder (waste activated sludge) is combined with
primary sludge before being sent to gravity thickening. Following the gravity thickener, the
sludge is sent for anaerobic digestion followed by further dewatering by centrifuge. Filtrate from
the gravity thickener, centrate from the centrifuge, and supernatant from the anaerobic digester
are returned to the influent stream at the headworks to the wastewater treatment system.
Dewatered sludge is transported to a landfill by truck.
1.2.4.9 Level 5-2: 5-Stage Bardenpho Membrane Bioreactor with Sidestream Reverse
Osmosis Treatment (Level 5-2, MBR/RO)
In the Level 5-2 5-Stage Bardenpho membrane bioreactor with sidestream RO
wastewater treatment configuration, wastewater first undergoes pretreatment and primary
treatment. Sludge from primary clarification enters a fermentation vessel to convert complex
proteins and carbohydrates to VFAs that provide an internal carbon source for biological nutrient
removal. Sludge from the fermenter is sent to gravity thickening. Primary clarifier effluent and
fermenter supernatant enters a 5-stage Bardenpho nutrient removal reactor wherein the
wastewater enters an anaerobic stage before alternating between anoxic and aerobic conditions in
a total of five successive steps for biological phosphorus removal, CBOD removal, and enhanced
nitrification and denitrification. There is an internal mixed liquor recycle that returns wastewater
from the first aerobic zone to the first anoxic zone. Following the Bardenpho reactor, additional
phosphorus in the wastewater is chemically precipitated, using aluminum salts, after which the
effluent moves along to membrane filtration to remove solids from the wastewater, generating
permeate (effluent) and a reject stream (sludge). In order to meet the designed effluent quality,
effluent then splits into two streams with 15 percent of the flow receiving no sidestream
treatment. The remaining 85 percent of flow undergoes a series of RO pre-treatment steps,
KP-C-16-003; WA 2^37
1-15
-------
Section 1: Goal and Scope Definition
including chlorine gas addition for biofouling control (followed by dechlorination with sodium
bisulfite due to low chlorine tolerance of the RO membranes); and antiscalant addition for scale
control. Following pretreatment, the effluent undergoes RO treatment, generating a permeate
(effluent) and reject stream (brine). Effluent from the RO unit is recombined with the 15 percent
stream for final disinfection using chlorine gas and dechlorinated using sodium bisulfite to
remove residual chlorine prior to discharge to surface water. Brine from the RO unit is disposed
of by injection into an onsite disposal well. A portion of sludge from the membrane filter is
returned to the influent of the Bardenpho (return activated sludge) while the remainder (waste
activated sludge) is combined with primary sludge before being sent to gravity thickening.
Following the gravity thickener, the sludge is sent for anaerobic digestion followed by further
dewatering by centrifuge. Filtrate from the gravity thickener, centrate from the centrifuge, and
supernatant from the anaerobic digester are returned to the influent stream at the headworks to
the wastewater treatment system. Dewatered sludge is transported to a landfill by truck.
KP-C-16-003; WA 2^37
1-16
-------
Section 1: Goal and Scope Definition
Table 1-5. Study Treatment Configuration Characteristics
1 iviilmonl l.e\el II)
I.I
1.2-1
1.2-2
1.3-1
1.3-2
1.4-1
1.4-2
1.5-1
1.5-2
('litiruclcri.slic
Dcscri/'lion
l.e\el 1.
AS
l.e\el 2-1.
\2()
l.e\el 2-2.
AS3-'
l.e\el 3-1.
155
l.e\el 3-2.
Ml (1
l.e\el 4-1.
Ii5/I)enil
l.e\el 4-2.
MIJR'
1 .c\ el 5-1.
U5/UO
l.e\el 5-2.
MBR/KO'
SK I ula>si
Primary Biological Process
lu
15
10
15
15
15
ly
15
21
Secondary Biological Process
-
-
50
-
-
attached13
.
attached13
-
Tertiary Biological Process
-
-
10
-
-
-
.
-
-
Quantify
nitrification
Primary Biological Process
Minimal
Partial
Minimal
High
High
High
High
High
High
Secondary Biological Process
.
.
High
.
.
N/A
Minimal
N/A
Minimal
Tertiary Biological Process
.
.
N/A
.
.
.
.
.
.
HRT (hours)d
Aerobic
5.7
8.8
6.0
10
10
10
5.3
10
6.2
Anoxic
-
6.0
6.2
7.4
8.2
10
2.6
9.2
3.7
Anaerobic
-
2.5
4.3
2.5
1.6
0.77
0.94
1.7
0.69
Total
5.7
17
16
20
20
21
8.8
21
11
Redox condition summaryd
Aero
An-Anox-
Aero
Aero-
Aero-An
An-Anox-
Aero-
Anox-
Aero
An-Anox-
Anox-Aero
An-Anox-
Aero-
Anox-
Aero-
Anox
Anox-
Aero-
Anox-Aero
An-Anox-
Aero-
Anox-
Aero-
Anox
An-Anox-
Aero-
Anox-Aero
MLSS
Concentration
(mg/L)
Primary Biological Process
2500
3000
2500
3000
3000
3000
9000
3000
9000
Secondary Biological Process
_
_
2500
_
_
N/A
9000
N/A
9000
Tertiary Biological Process
-
-
2500
-
-
-
-
-
-
a - Secondary biological process is a nitrification reactor. Tertiary biological process is denitrification reactor,
b - Secondary biological process is an attached growth denitrification reactor with an HRT of 1 hour,
c - Secondary biological process is membrane filter with an HRT of 1.78 hours,
d - Aggregates information for primary, secondary and tertiary biological processes.
KP-C-16-003; WA 2^37
1-17
-------
Section 1: Goal and Scope Definition
Nitrous Oxide
Emissions from
Receiving Stream
Figure 1-2. Level 1: Conventional Plug Flow Activated Sludge Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-18
-------
Section 1: Goal and Scope Definition
Process GH6
Emissions Nitrified
"td
/
/
£
1
Secondary
Clarification
Nitrous Oxide
Emissions from
Receiving
Stream
Transportation
Emissions and Process
and Biodegradation
emissions from Landfill
Figure 1-3. Level 2-1: Anaerobic/Anoxic/Oxic Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-19
-------
Section 1: Goal and Scope Definition
Nitrous Oxide
Emissions from
Recekf 'mg Stream
Figure 1-4. Level 2-2: Activated Sludge, 3-Sludge System Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-20
-------
Section 1: Goal and Scope Definition
Screenings Grit
Removal
Nitrified Process GHG
Recycle Emissions
t
Chemical
Precipitation
kcy
On-site wastewater
treatment plant
processes
Upstream energy
and materia I inputs
ProcessAir
Emissions
^uanrication r
Phosphorous
iprtation
Sand Rlter
Ch tori nation
Dechlorination
Waste Activated Sludge
Centrate
Gravity Thickener
Anaerobic
Digestion
Nitrous Oxide
Emissions from
Receiving Stream
Effluent
Discharge in
River
Transportation
Emissions and
Process and
Biodegrodation
Emissions from
Landfill
t
Hauling and
Landfilling
Diesel
Figure 1-5. Level 3-1: 5-Stage Bardenpho System Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-21
-------
Section 1: Goal and Scope Definition
Transportation
Emissions ond
Process ond
Biodeg nidation
Emissions from
Landfill
Hauling and
Landfilling
Diesel
Figure 1-6. Level 3-2: Modified University of Cape Town Process Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-22
-------
Section 1: Goal and Scope Definition
Nitrous Oxide
Emissions from
Receiving Stream
Figure 1-7. Level 4-1: 5-Stage Bardenpho System with Denitrification Filter Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-23
-------
Section 1: Goal and Scope Definition
Wastewater
Influent
Electricity
"j iL " "
Infrastructure
KFY
On-site wastewater
treatment plant
processes
Upstream energy
and material inputs
Process Air
Emissions
Screening & Grit
Removal
j \ r \
Return Activated Sludge
Membrane
Filter
Chlorine Gas
r
Ch tori nation
Waste Activated 9u<3ge
Centrate
Dech tori nation
Nitrous Oxide
Emissions from
Receding Stream
Effluent
Discharge in
River
Transportation
Emissions and
Process and
Biodegradation
Emissions from
Landfill
t
| Hauling and
Landfilling
Figure 1-8. Level 4-2: 4-Stage Bardenpho Membrane Bioreactor System Wastewater Treatment Configuration
Process GHG
Nitrified
-l-j.srj
Methanol
Emissions
Recycle
4-stage Biological Nutrient
Removal
Chemical
Phosphorous
Precipitation
Clarifier
EP-C-l6-003; WA 2-37
1-24
-------
Section 1: Goal and Scope Definition
Screening &Grit
Removal
Nitrified
Process GHG
t
I v ¦ 'CBTri.
'1
/
\ ¦
/
/
/
V
/
Chemical
Phosphorous
Precipitation
Nitrous Oxide
Emissions from
Receiving Stream
Transport Emissions and
Process and Bbdegnidation
Emissions from Landfill
Hauling and
Landfilling
Figure 1-9. Level 5-1: 5-Stage Bardenpho with Sidestreain Reverse Osmosis Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-25
-------
Section 1: Goal and Scope Definition
Figure 1-10. Level 5-2: 5-Stage Bardenpho Membrane Bioreactor with Sidestream Reverse Osmosis
Wastewater Treatment Configuration
EP-C-16-003; WA 2-37
1-26
-------
Section 1: Goal and Scope Definition
1.2.5 Metrics and Life Cycle Impact Assessment
Table 1-6 summarizes the metrics estimated in connection with each of the system
configurations, together with the method and units used to characterize each.
The cost of each system configuration is estimated using standard approaches for life
cycle costing, with more detail on the costing methodology provided in Section 2. Most of the
LCIA metrics are estimated using the Tool for the Reduction and Assessment of Chemical and
Environmental Impacts (TRACI), version 2.1 (Bare et al., 2003; Bare, 2011). TRACI is an LCIA
method developed by the U.S. EPA. It includes a compilation of methods representing current
best practice for estimating human health and ecosystem impacts based on U.S. conditions in
conjunction with the information provided by life cycle inventory models. Toxicity impacts (e.g.,
human health toxicity - cancer, human health toxicity - non-cancer, and ecotoxicity) are based
on the USEtox™ method (Rosenbaum et al., 2011) version 2.02. Global warming potential
(GWP) is estimated in the baseline results using the 100-year characterization factors provided
by the Intergovernmental Panel on Climate Change (IPCC) 4th Assessment Report, which are the
GWPs currently used for international reporting (Myhre et al., 2013). GWPs are also estimated
in a sensitivity analysis using the more recent 100-year characterization factors provided by the
IPCC 5th Assessment Report. In addition to TRACI, the ReCiPe LCIA method is used to
characterize water consumption and fossil energy use (Goedkoop et al., 2008), impacts which are
not included in the current version of TRACI. To provide another perspective on energy,
cumulative energy demand including the energy content of all non-renewable and renewable
energy resources extracted throughout the supply chains associated with each configuration is
estimated using a method adapted from one provided by the Ecoinvent Centre (Ecoinvent Centre,
2010a). Detailed descriptions of each of the LCIA impact categories are also provided in Section
4.6.
The metrics included in this study range in geographic scale from global metrics such as
GWP and fossil fuel depletion potential, to impact categories such as ecosystem toxicity
potential, smog formation potential, and eutrophication potential that tend to be more local or
regional in nature. In other words, some emissions/pollutants result in environmental impacts on
a global level (e.g., emissions with long atmospheric lifetimes like greenhouse gases), while
other pollutants primarily impact the regions or locations close to the point of release.
Table 1-6. Metrics Included in the LCA and LCCA Results
Metric
Method
I nil
C'os>l
LCCA
USD2014
Eutrophication Potential
TRACI 2.1
kg N eq.
Cumulative Energy Demand
ecoinvent
MJ-eq.
Global Warming Potential
TRACI 2.1
kg C02 eq.
Acidification Potential
TRACI 2.1
kg S02 eq.
Fossil Depletion
ReCiPe
kg oil eq.
Smog Formation Potential
TRACI 2.1
kg 03 eq.
Human Health - Particulate Matter Formation
TRACI 2.1
PM2 5 eq.
EP-C-I6-QQ3; WA 2^37
1-27
-------
Section 1: Goal and Scope Definition
Table 1-6. Metrics Included in the LCA and LCCA Results
Mel ik-
Method
I nil
Ozone Depletion Potential
TRACI 2.1
kg CFC-11 eq.
Water Depletion
ReCiPe
m3
Human Health Toxicity - Cancer Potential
USEtox™ 2.02
CTUh
Human Health Toxicity - Noncancer Potential
USEtox™ 2.02
CTUh
Ecotoxicity Potential
USEtox™ 2.02
CTUe
KP-C-16-003; WA 2^37
1-28
-------
Section 2: Trace Pollutant Removal Performance Characterization
2. Trace Pollutant Removal Performance Characterization
Although the nine wastewater configurations evaluated in this study are designed to
achieve various levels of nutrient removal targets, these treatment trains also remove other trace
pollutants in the influents. It is important to capture these treatment performances in the holistic
analysis in order to have a complete understanding of treatment strategies. This section
summarizes the steps taken to characterize three major groups of trace pollutants with respect to
their expected influent concentrations, fate within the study's nine wastewater treatment
configurations, and final discharge into the environment. The groups include heavy metals, toxic
organics and disinfection byproducts (DBPs). Depending on the pollutant, the final receiving
environment (and thus the potential for impact) may include surface water discharge from the
WWTP, partitioning to sludge with subsequent landfill disposal, or deep well injection in the
case of RO brine. It was assumed that no toxicity-related impacts were associated with deep well
injection. Volatilization was not found to be a major loss pathway for any of the included
pollutants.
In the case of landfill disposal, environmental impact only occurs if the landfill liner fails
and leachate is released. However, little data exists on actual failure rates. For this study, a
failure rate of 5% was assumed based on a probabilistic modeling study that found, given typical
landfill construction, failures generally occur within 10-30 years after landfill closure (Pivato,
2011).
For further reference, a full description of background, methods and results is provided in
Appendix B, Appendix C and Appendix D, for heavy metals, toxic organics and DBPs,
respectively.
2.1 Heavy Metals
The discharge of metals to the environment represents an ever-present concern, given
their potential toxicity at even trace levels. WWTPs receive variable but sometimes high loads of
metals depending on the mix of sources in their watershed, which can include industrial
activities, domestic sources and stormwater (Yost et al., 1981; Ruel et al., 2011; Choubert et al.,
2011b).
The direct management of metals has generally not been the focus of municipal WWTP
design given the prioritization of organics and nutrient treatment. Heavy metals from industrial
source are subject to other more targeted regulatory programs like the National Pretreatment
Program (U.S. EPA, 2019a) which applies to industrial facilities. Nevertheless, trace heavy
metals may still be present in municipal influents. Many common treatment processes allow for
effective partitioning of metals to the sludge fraction, thus greatly reducing the quantity
discharged in effluent.
Seven metals were included in this study that are commonly regulated and prevalent in
the case study literature. Both criteria were assumed to be indirect indicators of the metal's
demonstrated potential to cause environmental or human health impacts. The metals include
Cadmium (Cd), Chromium (Cr), Copper (Cu), Mercury (Hg), Nickel (Ni), Lead (Pb), and Zinc
(Zn). Table 2-1 summarizes ranges of influent concentrations established in several literature
KP-C-16-003; WA 2^37
2-1
-------
Section 2: Trace Pollutant Removal Performance Characterization
reviews, relevant effluent limits, and ranges of influent concentrations observed in the case
studies used herein.
KP-C-16-003; WA 2^37
2-2
-------
Section 2: Trace Pollutant Removal Performance Characterization
Table 2-1. Summary of Literature and Case Study Metal Influent Concentrations and
Regulatory Effluent Concentrations.
( oncciili'iilions in Hii/I.
Value
PI)
( ii
/.n
Ni
Ci-
( (1
lis
Soles
Source
Influent
Concentrations -
5."
o3
181
11
HJ
njl
n.3o
19 Plains, franco
1
25
78
155
14
12.0
0.8
0.5
30 Plants, UK
2
Literature
Reviews
140-600
—
Combined WW
3
232
489
968
455
378
19
—
12+ Cities, US
4
Case
High
68
118
493
77
290
10
7.0
This Study
5
Study
Medium
21
65
350
24
59
4.9
3.8
This Study
5
Ranges
Low
10.8
25
204
11
19
0.94
0.37
This Study
5
US CCCa
2.5
9
120
52
74/1 lb
0.25
0.77
Effluent Limits
6
US CMC3
65
13
120
470
570/16b
2
1.4
Effluent Limits
6
a - Criterion Continuous Concentration/Criteria Maximum Concentration, hardness dependent except for Cr (VI)
and Hg. Values shown assume a hardness of 100 mg/L.
b - Chromium (III/VI)
1 - Choubert et al., 201 lb; Ruel et al., 2012
2 - Rule et al., 2006
3 - Metcalf and Eddy, 2014
4 - Yostetal., 1981
5 - Linstedt et al., 1971; Brown et al., 1973; Chen et al., 1974; Oliver and Cosgrove, 1974; Aulenbach and Chan,
1988; Huang et al., 2000; Innocenti et al., 2002; Chipasa, 2003; Karvelas et al., 2003; Qdais and Moussa,
2004; Buzier et al., 2006; da Dilva Oliveira et al., 2007; Mohsen et al., 2007; Obarska-Pempkowiak and
Gajewska, 2007; Carletti et al, 2008; Johnson et al., 2008; Dialynas and Diamadopoulos, 2009; Renman et
al., 2009; Malamis et al., 2012; Arevalo et al., 2013; Garcia et al., 2013; Salihoglu, 2013; Inna et al., 2014;
Reddy et al., 2014
6-U.S. EPA, 2019b
Metal removal efficiencies for study system configurations were estimated based on a
detailed literature review of performance results from similar systems. For system levels where
no representative equivalent was identified but the important components were characterized, a
composite removal efficiency was calculated based upon case study performance data of its
major unit processes. For example, Level 3-1 includes a 5-stage Bardenpho process with
subsequent sand filtration. However, results of the literature review only identified 5-stage
Bardenpho WWTPs without sand filtration, and sand filtration as a standalone process.
Therefore, a composite removal efficiency was calculated assuming a realistic stepwise removal,
combining removal efficiencies for a 5-stage Bardenpho process with removal efficiencies for
sand filtration. Table 2-2 summarizes the resulting minimum, average and maximum removal
efficiencies for each treatment configuration. Supporting details for calculations and calculation
assumptions are provided in Appendix B.
KP-C-16-003; WA 2^37
2-3
-------
Section 2: Trace Pollutant Removal Performance Characterization
Table 2-2. Summary of Estimated Metal Removal Efficiencies3
l.cu-1 1
l.e\el 2-1
l.e\el 2-2
l.e\el 3-1
l.e\el 3-2
l.e\el 4-1
l.e\el 4-2
1 .e\ el 5-1
1 .e\ el 5-2
Melsil
AS
A2()
A S3
155
Ml (1
Ii5/I)enil
MliK
IJ5/UO
MliK/KO
Mm
'5"u
'5"u
'5"u
"5%
5:%
"5%
«r,%
Cu
Mean
62%
62%
62%
80%
77%
80%
90%
97%
99%
Max
84%
84%
84%
83%
96%
83%
99%
98%
100%
Min
40%
40%
40%
55%
39%
55%
68%
95%
97%
Pb
Mean
65%
65%
65%
66%
70%
66%
88%
96%
99%
Max
97%
97%
97%
75%
94%
75%
100%
97%
100%
Min
16%
16%
16%
42%
66%
42%
64%
82%
91%
Ni
Mean
39%
39%
39%
45%
67%
45%
82%
90%
97%
Max
91%
91%
91%
47%
68%
47%
100%
94%
100%
Min
12%
12%
12%
57%
83%
57%
75%
94%
97%
Zn
Mean
42%
42%
42%
72%
89%
72%
85%
96%
99%
Max
77%
11%
77%
83%
94%
83%
91%
98%
99%
Min
11%
11%
11%
40%
23%
40%
96%
93%
99%
Cd
Mean
59%
59%
59%
47%
41%
47%
97%
94%
100%
Max
83%
83%
83%
57%
59%
57%
98%
95%
100%
Min
16%
16%
16%
78%
88%
78%
83%
97%
99%
Cr
Mean
64%
64%
64%
81%
88%
81%
91%
98%
100%
Max
79%
79%
79%
84%
89%
84%
95%
98%
100%
Min
17%
17%
17%
17%
17%
17%
93%
84%
98%
Hgb
Mean
53%
53%
53%
53%
53%
53%
97%
93%
100%
Max
85%
85%
85%
85%
85%
85%
99%
98%
100%
a - "Removal Efficiency" used loosely; data more explicitly represents partitioning to sludge. Min and max represent minimum and maximum removal
efficiencies reported in the literature. Where removal efficiencies are composites of multiple processes, minimum represents the composite of both
contributing minimums, likewise for maximum.
b - No data for Hg removal found for 4-stage Bardenpho, 5-stage Bardenpho or MUCT. Therefore, conservatively assumed same removal for these biological
treatment processes as documented for CAS (Level 1). Data for Levels 4-2, 5-1 and 5-2 represent the effect of tertiary polishing step alone, i.e. MBR and
RO.
KP-C-16-003; WA 2^37
2-4
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Section 2: Trace Pollutant Removal Performance Characterization
2.2 Toxic Organic Pollutants
Toxic organics are a diverse and growing category of chemical substances that includes
commonly referred to pollutant groups such as contaminants of emerging concern (CECs),
pharmaceuticals and personal care products (PPCPs), and endocrine disrupting chemicals
(EDCs). The pollutant category includes medications, fragrances, insect repellents and other
household items that can be harmful to environmental and human health at even trace levels
(U.S. EPA, 2015; Montes-Grajales et al., 2017). Per- and polyfluoroalkyl substances (PFAS) are
not included in this study.
Toxic organics are present in surface waters, groundwater, wastewater and WWTP
effluent, both in the U.S. and globally (Ellis, 2008; Ebele et al., 2017; Montes-Grajales et al.,
2017). No comprehensive list exists, though based on a diverse literature the number of
contaminants is at least in the hundreds (if not thousands) and is continually being expanded
upon as analytical techniques for measuring both presence and toxicity are continually refined. In
order to provide a targeted analysis of their behavior in WWTPs, a restricted group of 43
pollutants (Table 2-3) has been included in this study. The list has been adapted and updated
from two previous studies (Montes-Grajales et al., 2017; Rahman et al., 2018) where pollutants
were selected based on frequency of detection in WWTPs and the availability of information
regarding concentration, degradation, transformation and removal.
The concentration of trace pollutants can vary considerably on a daily and seasonal basis
and between WWTPs (Martin Ruel et al., 2012). Based on a detailed review of the literature,
influent concentration ranges were established for each pollutant (Table 2-3). For subsequent
calculations, the medians of pollutant influent concentrations were used as means had a tendency
to be biased by a small number of very high concentrations.
EP-C-I6-QQ3; WA 2^37
2-5
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Section 2: Trace Pollutant Removal Performance Characterization
Table 2-3. Occurrence of the Selected Toxic Organic Compounds in WWTP Influent
Chemical Name
Chemical Tvpe/l so
I
A\erase
llliienl Cone
Median
j-ntration ( lii*/
Minimum
L)
Maximum
Sample Si/e
acetaminophen3
pain reliever, anti-
inflammatory
97
19
0.02
400
12
androstenedione3
steroid hormone
0.29
0.10
0.02
1.3
7
atenolol
beta blocker
4.3
1.1
0.03
26
10
atorvastatin
lipid regulator
0.49
0.22
0.07
1.6
6
atrazineb
pesticide
0.02
0.02
1.0E-3
0.06
5
benzophenone
PCP, sunscreen
0.24
0.27
7.0E-3
0.42
4
bisphenol A
EDC, plasticizer
4.6
0.84
0.01
44
16
butylated hydroxyanisolec
beta blocker
1.3
0.16
0.13
3.5
3
butylated hydroxytoluene
beta blocker, cosmetic
0.93
0.41
0.05
3.5
5
butylbenzyl phthalated
plasticizer
0.11
0.11
0.08
0.14
2
carbamazepine3
anti-convulsant
0.92
0.69
0.04
3.8
28
N,N-diethyl-meta-toluamide (DEET)
insect repellent
1.4
0.40
0.02
6.9
6
diclofenac
analgesics, anti-
inflammatory
2.1
0.96
1.0E-3
17
20
dilantin
anti-seizure medication
0.16
0.17
0.05
0.24
4
dioctyl phthalateb
plasticizer, industry
23
1.4
1.1
67
3
estradiol30
EDC, steroid hormone
0.59
0.03
8.0E-3
5.0
11
estrone30
EDC, steroid hormone
0.17
0.05
0.01
1.0
9
galaxolide
beta blocker, PCP,
fragrance
4.3
2.3
1.4E-3
25
16
gemfibrozil3
lipid regulator
3.1
1.6
0.02
22
15
hydrocodone
analgesic, opioid
0.08
0.11
0.02
0.12
5
ibuprofen3
analgesics, anti-
inflammatory
7.8
2.4
1.0E-3
39
27
iopromide
contrast agent
7.4
0.05
0.01
38
6
meprobamate
tranquilizer, medication
0.40
0.35
0.01
0.97
5
naproxen3
analgesics, anti-
inflammatory
8.5
2.5
2.0E-3
53
20
nonylphenolbc
EDC, disinfectant,
surfactant, solvent
3.4
2.3
0.02
9.7
14
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2-6
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Section 2: Trace Pollutant Removal Performance Characterization
Table 2-3. Occurrence of the Selected Toxic Organic Compounds in WWTP Influent
Chemical Name
Chemical Tvpe/l so
I
A\erase
llliienl Cone
Median
j-ntration ( lii*/
Minimum
L)
Maximum
Sample Si/e
octylphenolb
EDC, surfactant,
solvent
1.9
0.41
0.12
8.7
12
o-hydroxy atorvastatin
lipid regulator
0.12
0.12
0.10
0.14
2
oxybenzone
PCP
1.2
0.39
0.03
3.8
4
p-hydroxy atorvastatin
lipid regulator
0.12
0.12
0.10
0.14
2
progesterone3
EDC
0.02
0.01
3.1E-3
0.06
4
sulfamethoxazole3
antibiotic
1.1
0.43
0.04
4.5
14
tris(2-chloroethyl) phosphate (TCEP)
flame retardant,
plasticizer
0.35
0.24
0.17
0.65
3
tris(2-chloroisopropyl) phosphate
(TCPP)
flame retardant
1.2
1.2
1.1
1.3
2
testosterone3
EDC
0.06
0.05
0.01
0.14
5
triclosan3
pesticide, disinfectant
2.7
0.80
2.3E-3
24
17
trimethoprim3
antibiotic
0.52
0.53
0.10
1.4
8
triclocarban3
disinfectant
0.42
0.42
0.29
0.54
2
tonalide
beta blocker, PCP,
fragrance
1.5
0.80
5.0E-5
7.6
13
celestolide
PCP, fragrance
5.1
0.07
0.04
15
3
phantolide
fragrance
0.10
0.10
0.04
0.15
2
clofibric acid
lipid regulator
0.46
0.29
0.03
1.1
3
musk ketone
fragrance
0.12
0.12
0.10
0.15
3
diuronbc
fragrance
0.14
0.11
0.05
0.25
3
a - Identifies substances with EPA developed analytical methods for detection of contaminants of emerging concern per (EPA, 2017).
b -Identifies substances with a European Quality Standard per (European Parliament, 2008).
c - Identifies substances identified in EPA's Candidate Contaminant List (CCL), version 4 (U.S. EPA, 2016c). The CCL identifies chemicals that are currently
unregulated but may pose a risk to drinking water,
d - Identifies substances identified as human health criteria in Section 304(a) of the Clean Water Act (U.S. EPA, 2019c).
Table Acronyms: EDC - endocrine disrupting chemical, PCP - personal care product.
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2-7
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Section 2: Trace Pollutant Removal Performance Characterization
The behavior of toxic organics within study treatment configurations was estimated based
on a review of the relevant literature for major unit processes, including:
• Biological Treatment
• Chemical Phosphorus Removal
• Membrane Filtration
• Anaerobic Digestion
Given the large list of pollutants and varying levels of available information, a
combination of quantitative and qualitative information was used to arrive at final treatment
performance ranges. The ranges take into account possible loss pathways that include
transformation or degradation within biological unit processes, partitioning to solids and
transformation or degradation during anaerobic digestion. Table 2-4 provides the resulting
estimated range of cumulative removal efficiency for each of the nine WWTP configurations.
Degradation and removal efficiency estimates were calculated as a weighted average of values
for the 43 included pollutants. Relative influent concentration was used as the weighting factor.
Additional background discussion and supporting calculations are provided in Appendix C.
Table 2-4. Summary of Cumulative Toxic Organics Degradation and Removal Efficiency
in Study Treatment Configurations3
TiViitmcnt
1 r
K'tion Degraded
Tnii'lion Romo\oil (includes solids)
l.e\el
Minimum
Modi :t n
Miixiiiiiiin
Minimum
Modiiin
Maximum
LI
52%
70%
85%
67%
81%
89%
L2-1
52%
73%
90%
67%
86%
95%
L2-2
52%
73%
90%
67%
86%
95%
L3-1
52%
75%
92%
67%
88%
97%
L3-2
52%
75%
92%
67%
88%
97%
L4-1
52%
75%
92%
67%
88%
97%
L4-2
52%
75%
91%
67%
88%
97%
L5-1
52%
75%
91%
94%
99%
100%
L5-2
52%
75%
91%
93%
98%
99%
a - Table values represent the cumulative effect of all the described treatment processes, calculated as a weighted
average of the 43 toxic organics using influent concentration as the weighting factor.
2.3 Disinfection Byproducts
Disinfection of WWTP effluent is a necessary practice to minimize the acute risk
associated with exposure to microbial pathogens, however it must be balanced with the chronic
risk posed by the creation of disinfection byproducts (DBPs). DBPs are a class of chemical
compounds that can be harmful to both aquatic and human health (Boorman, 1999;
Nieuwenhuijsen et al., 2000; Mizgireuv et al., 2004; Villanueva et al., 2004; Muellner et al.,
2007; Richardson et al., 2007; Watson et al., 2012).
DBPs are formed when DBP precursors, generally organic carbonaceous or nitrogenous
compounds, are oxidized during chlorination or chloramination (Christman et al., 1983). By
regulation, certain DBPs are managed at drinking water treatment plants, as their presence in
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2-8
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Section 2: Trace Pollutant Removal Performance Characterization
water supplies poses a direct threat to human health (Sedlak and Gunten, 2011; US EPA, 2015c).
Furthermore, as water recycling and reclamation programs expand (and as indirect potable reuse
continues), management of DBPs and DBP precursors has become increasingly important at the
WWTP as well (Krasner et al., 2008; Tang et al., 2012).
The importance of DBP and DBP precursor control at WWTPs has been growing in
recent years for several reasons. First, the type of precursors formed through biological
wastewater treatment are complex and, although overlapping with, are in many ways dissimilar
from the natural organic matter (NOM)-derived precursors of drinking water-based DBPs.
Therefore, lessons learned in drinking water DBP formation prediction and control are not
directly translatable to WWTPs (Drewes and Croue, 2002; Tang et al., 2012). Additionally, there
has been increasing concern over emerging and more toxic nitrogenous DBPs such as
nitrosamines, halonitroalkanes, haloacetonitriles (HANs) and haloacetamides (Westerhoff and
Mash, 2002; Joo and Mitch, 2007; Lee et al., 2007), which can be produced to varying degrees
from dissolved organic nitrogen (DON) found in wastewater and WWTP effluent.
Haloacetamides and HANs in particular are approximately two orders of magnitude more
cytotoxic and genotoxic than the regulated trihalomethanes (THMs) and haloacetic acids (HAAs)
(Muellner et al., 2007; Plewa and Wagner, 2009). The concentration of ammonia further
complicates DBP formation kinetics, favoring the formation of certain groups at high
concentrations and others at low (Krasner et al., 2008; Krasner et al., 2009b; Sedlak and Gunten,
2011). Similarly, chlorination practices, which can vary considerably between WWTPs, can have
large effects on the overall formation of DBPs and, in combination with ammonia
concentrations, can favor certain DBP groups over others. It is therefore important that
comparisons of treatment configurations with differing nitrification and denitrification
capabilities take into account multiple groups of DBPs that can capture these relative benefits
and drawbacks.
For this study, models for DBP formation potential (FP) were used to compare the
differences in DBP formation between study treatment configurations. FP is determined using a
standardized procedure, eliminating variability from case study data that may arise owing to
different disinfection practices. Ultimately, this allows for a clearer distinction between the
effects of different treatment approaches on precursor control. To model disinfection byproduct
formation potential (DBPFP), a comprehensive dataset linking effluent water quality of 23
different WWTPs to DBPFP was used (Krasner et al., 2008). The DBP and DBP groups included
in the study include the regulated carbonaceous DBPs (THMs and HAAs) along with emerging
and more toxic carbonaceous and nitrogenous DBPs (Table 2-5).
Table 2-5. Summary of Study Disinfection Byproducts
Kc^ulalon
DliP (liroiip/coinpoiiiid)
( haraclcrislics
Precursors
l.iinil
An I lioril >
Trihalomethanes (THM)a'b
Chloroform
influent
Bromodichloromethane (BDCM)
carbonaceous,
refractory NOM,
EfOM, nitrified
effluent, humic
compounds
80 ng/L
U.S. EPA,
Stage 1/2 DBP
Rule
Chlorodibromomethane (DBCM)
halogenated
(TTHM)
Bromoform
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Section 2: Trace Pollutant Removal Performance Characterization
Table 2-5. Summary of Study Disinfection Byproducts
DBP (^roup/com pound)
( haraclerislics
Precursors
l.imil
Ke^ulalnn
An t ho ri I \
Haloacetic Acids (HAA)b'c
Monochloroacetic acid
influent
refractory NOM,
EfOM, nitrified
Dichloroacetic acid (DXAA)
carbonaceous,
halogenated
60 ng/L
(HAA5)
U.S. EPA,
Trichloroacetic acid (TXAA)
Stage 1/2 DBP
Bromoacetic acid
effluent, humic
compounds
Rule
Dibromoacetic acid
Nitrosaminesd
Y-nitrosodimcthvlaminc (NDMA)
nitrogenous,
unhalogenated
DON,
dimethylamine
10 ng/L
CA (action
level)
Aldehydes
Formaldehyde
Acetaldehyde
carbonaceous,
halogenated
DON, amino
acids
Chloroacetaldehyde
N/A
N/A
Dichloroacetaldehyde
Trichloroacetaldehyde (chloral hydrate)
Haloacetonitriles (HANs)
Chloroacetonitrile
Bromoacetonitrile
Iodoacetonitrile
T richloroacetonitrile
nitrogenous,
halogenated
DON, amino
acids
N/A
N/A
Bromodichloroacetonitrile
Dibromochloroacetonitrile
T ribromoacetonitrile
a - The four compounds together comprise the four primary trihalomethanes, sometimes referred to as TTHM or
THM4
b - https://nepis.epa.gov/Exe/ZyPDF.cgi?Dockey=P100C8XW.txt (U.S. EPA, 2015b)
c - These five compounds together comprise the five primary haloacetic acids, sometimes referred to as HAA5
d - California Department of Health Services, action level (CDHS, 2018)
Multiple linear regression models were constructed linking relevant water quality
parameters with DBPFP. This was done by first performing a linear correlation analysis, which
indicated COD and TKN to be the most influential predictors. Next, models were built for each
DBP group (Table 2-5) using the adjusted coefficient of determination (R2). Final models were
significant at a >95% confidence level with the exception of NDMA, which was significant at a
93% confidence level. Table 2-6 gives model results for the nine study treatment configurations.
Further discussion of methods, model construction and model results can be found in Appendix
D.
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2-10
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Section 2: Trace Pollutant Removal Performance Characterization
Table 2-6. DBPFP Model Results for Study Treatment Configurations
Study ( <)nli
-------
Section 3: Life Cycle Cost Analysis Methodology
3. Life Cycle Cost Analysis Methodology
This section presents ERG's methodology for developing life cycle costs for the nine
greenfield wastewater treatment configurations included in this study. As such, the costs
presented in the report are not applicable to operations that retrofit existing treatment systems to
achieve further nutrient removal, and the difference from one treatment level to another may not
represent the incremental retrofit costs due to existing infrastructure and site-specific conditions.
In addition, the costs (as well as life cycle impacts discussed later in the report) are for the entire
wastewater treatment configuration, not just those steps used to achieve nutrient removal.
The life cycle costs in the study are based primarily on the use of CAPDETWorks™, a
model that performs planning-level design and cost estimation of WWTP construction projects.
These planning-level costs do not include site-specific factors that may impact the costs (e.g.,
high groundwater table, shallow bedrock, deep excavation) as they are intended to represent the
national average. These costs are supplemented with costs for additional unit processes that are
not included in CAPDETWorks™ to provide costs for the entire wastewater treatment
configuration. Section 3.1 describes CAPDETWorks™ and the data sources used for the
additional unit processes. Section 3.2 describes the engineering cost estimation methodology. To
the extent possible, purchased equipment and annual cost results are developed by unit process to
allow for consistent presentation alongside results of the LCA model. Section 3.3 describes the
life cycle cost analysis (LCCA) calculations that provide for a plant-level comparison of costs
that occur throughout the life of the wastewater treatment configurations. The total plant costs
are presented as: 1) total capital costs and total annual costs and 2) net present value that
combines the one-time capital costs and annual costs into one value. The capital costs include the
purchased equipment, direct costs (e.g., site preparation, site electrical, yard piping), and indirect
costs (e.g., land, engineering design fee, interest during the 3-year construction period). The
annual costs include the operating and maintenance labor, materials including replacement
equipment, chemicals, and energy. In general, the purchased equipment costs were based on
equipment sizing for the 20 MGD peak flow rate, while the annual costs were based on the 10
MGD annual average flow rate. For the net present value, the construction costs (in present
value) are combined with the discounted annual costs during the WWTP planning period.
Section 3.4 describes the quality of the data sources used in the LCCA.
3.1 Data Sources
ERG obtained cost data from the following sources or categories of sources:
• CAPDETWorks™ Version 3.0 (Hydromantis, 2014)
• EPA reports and fact sheets
• Striking the Balance Between Nutrient Removal in Wastewater Treatment and
Sustainability (Falk et al, 2011)
• Wastewater treatment design textbooks
• Personal communication with technology vendors
• RSMeans Building Construction Cost Data (RSMeans, 2010)
• RSMeans Construction Cost Index (RSMeans, 2017)
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3-1
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Section 3: Life Cycle Cost Analysis Methodology
The majority of the life cycle costs are based on CAPDETWorks™ Version 3.0
(Hydromantis, 2014) modeling output, supplemented with costs for unit processes that are not in
CAPDETWorks™ (see Section 3.2.2 for details). EPA and the U.S. Army Corps of Engineers
originally developed CAPDETWorks™ as a planning tool for WWTPs; Hydromantis
Corporation now maintains and updates CAPDETWorks™. As described in Section 4.2.1 of
Municipal Nutrient Removal Technologies Reference Document (U.S. EPA, 2008b),
CAPDETWorks™ is used as follows:
The user generates a process layout involving a number of unit operations. The user can
also define input variables, including wastewater flow rate, wastewater influent quality,
and desired effluent quality or other performance coefficients. Alternatively, the user can
choose to use default values developed by Hydromantis. The software then calculates the
required sizes of the unit operations and uses cost-curve models from the software's
database to estimate the capital, labor, chemical, and energy costs that would be incurred.
.. .The model uses several standard indices to update costs to current dollars: the
Engineering News-Record (ENR) Construction Cost Index, the Marshall & Swift Index,
and the Pipe Index. Values were obtained from a U.S. Department of Agriculture Web
site (USD A, 2007) that transcribes historical values of these indices.
The cost functions included in CAPDETWorks™ Version 3.0 (the version used for this study)
were updated in 2014. CAPDETWorks™ also allows users to input design values for each unit
process (e.g., solids retention time, surface overflow rate) or use the default values developed by
Hydromantis. CAPDETWorks™ also allows users to input unit costs (e.g., concrete,
construction labor rate, polymer).
ERG relied primarily on the following two EPA reports to evaluate and modify, as
necessary, the default input design values in CAPDETWorks™ and support development of
costs for the unit processes that are not in CAPDETWorks™:
• Municipal Nutrient Removal Technologies Reference Document (U. S. EPA, 2008b)
• Nutrient Control Design Manual (U.S. EPA, 2010)
The Municipal Nutrient Removal Technologies Reference Document (U.S. EPA, 2008b)
is intended to provide information to assist local decision makers and regional and state
regulators in planning cost-effective nutrient removal projects for WWTPs. This EPA report
provides capital and operation and maintenance costs for case study WWTPs, as well as costs
estimated using CAPDETWorks™. The purpose of the Nutrient Control Design Manual (U.S.
EPA, 2010) is to provide guidance and design considerations for nitrogen and phosphorus
control using biological nutrient removal and chemical phosphorus removal for WWTPs.
ERG also relied on Striking the Balance Between Nutrient Removal in Wastewater
Treatment and Sustainability (Falk et al, 2011), a report published by Water Environment
Research Foundation (WERF). This report is an LCA/LCCA evaluation of WWTPs with
nitrogen and phosphorus treatment technologies to achieve five levels of effluent nutrient targets
that match the five levels included in this study. While the WERF study used a different cost
estimation tool, ERG used the WERF design input values to evaluate and modify, as necessary,
the default input design values in CAPDETWorks™. ERG also used Wastewater Engineering -
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3-2
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Section 3: Life Cycle Cost Analysis Methodology
Treatment and Resource Recovery (Tchobanoglous et al., 2014), a wastewater treatment design
textbook, and the following documents to verify the default input design values and unit costs in
CAPDETWorks™:
• Wastewater Technology Fact Sheet - Screening and Grit Removal (U. S. EPA, 2003b)
• Biosolids Technology Fact Sheet - Gravity Thickening (U.S. EPA, 2003a)
• May 2016 National Industry-Specific Occupational Employment and Wage Estimates
for NAICS 221300 - Water, Sewage and Other Systems (U.S. DOL, 2017)
EPA's wastewater and biosolids technology fact sheets provide general design and cost
information. ERG used these technology fact sheets to evaluate and modify, as necessary, the
default input design values in CAPDETWorks™. ERG also compared the purchased equipment
process costs from CAPDETWorks™ to the technology fact sheets and updated the purchased
equipment costs where appropriate. The May 2016 National Industry-Specific Occupational
Employment and Wage Estimates for NAICS 221300 - Water, Sewage and Other Systems (U.S.
DOL, 2017) calculates average wages from data collected in a national survey of employers of
every size, state, and industry for metropolitan and nonmetropolitan areas. ERG used this report
to verify and update as necessary the labor rates in CAPDETWorks™ where appropriate.
The primary source of costs for the unit processes that are not in CAPDETWorks™ are
from personal communication with technology vendors. ERG contacted companies that
manufacture, distribute, or install dechlorination, ultrafiltration, reverse osmosis, and deep well
injection systems. The vendors provided the following types of information for EPA's analysis:
• Operations and maintenance requirements (e.g., equipment replacement frequency)
• Ancillary equipment required for the system (e.g., antiscalant chemicals)
• Capital cost information
• Operations and maintenance cost information, including energy requirements
ERG used vendor contacts from previous studies for the dechlorination system costs
(ERG, 201 la; ERG, 201 lb; ERG, 201 lc) and contacted vendors for information on
ultrafiltration, reverse osmosis, and deep well injection as part of this study (ERG, 2015a; ERG,
2015b). The majority of the vendors provided supporting documentation, which were also used
to develop the cost estimates for the unit processes not included in CAPDETWorks™.
ERG supplemented the information provided by vendors with unit costs for building
components from the RSMeans Building Construction Cost Data (RSMeans, 2010) to calculate
costs for general components of the unit processes not in CAPDETWorks™ (e.g., reinforced
concrete basins). ERG used RSMeans Construction Cost Index (RSMeans, 2017) to convert
costs obtained outside of CAPDETWorks™ to 2014 $ for consistency.
3.2 Engineering Cost Estimation
ERG developed engineering cost estimates that included the following components:
• Capital costs (one-time costs).
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3-3
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Section 3: Life Cycle Cost Analysis Methodology
• Operation and maintenance costs that reoccur annually or on a set frequency (e.g., 5-
year recurring costs for equipment replacement).
Capital costs include the purchased equipment, direct, and indirect costs to design and
build the wastewater treatment configuration. Operating and maintenance costs include the
operation and maintenance labor, materials, chemicals, and energy required to ensure long-term
operation of the WWTP. In general, the capital costs are based on the 20 MGD maximum flow
rate, while the operating and maintenance costs are based on the 10 MGD average flow rate.
Section 3.2.1 presents the calculations to convert all of the costs to a consistent dollar
basis. Section 3.2.2 presents ERG's methodology for calculating the capital and operating and
maintenance costs for the individual unit processes included in the wastewater treatment
configurations. These unit process costs are presented alongside results from the LCA model and
used in the LCCA. Discussion of the methodology for estimating the wastewater treatment
configuration-wide direct and indirect costs is presented in Section 3.3.
3.2.1 Dollar Basis
The majority of the life cycle costs are based on CAPDETWorks™ modeling output,
supplemented with costs for unit processes that are not in CAPDETWorks™. output is provided
in 2014 dollars. As a result, ERG standardized and presented all costs in 2014 dollars using
Equation 1 and the RS Means Historical Cost Index, presented in Figure 3-1.
Cost (2014 $) = Cost (20XX I)
Equation 1
where:
Cost (2014 $) = Cost in 2014 dollars
Cost (20XX $) = Cost in pre- or post-2014 dollars, where XX represents the specific year
2014 Cost Index = 204.9
20XX Cost Index = See Figure 3-1, using the Historical Cost Index where January 1,
1993=100
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Section 3: Life Cycle Cost Analysis Methodology
Historical Cost Indexes
The table below lists both die RSMeans® historical cost index based on
Jan. 1,1993 = 100 as well as the computed value of an index based on
Jan. 1,2017 costs. Since die Jan. 1,2017 figure is estimated, space is left
to write in die actual index figures as they become available through
the quarterly RSMeans Construction Cost Indexes.
Historical
Current Index
Historical
Current Index
Historical
Current Index
Cost Index
Based on
Cost Index
Based on
Cost Index
Based on
Year
Jan. 1.1993 = 100
Jan. 1, 2017 = 100
Year
Jan. 1.1993 = 100
Jan. 1. 2017 = 100
Year
Jan. 1.1993 = 100
Jan. 1, 2017 = 100
Est.
Actual
Est.
Actual
Actual
Est.
Actual
Actual
Est.
Actual
Oct 2017"
July 2002
128.7
61.7
July 1984
82.0
39.3
July 2017"
2001
125.1
60,0
1983
80.2
38.4
April 2017'
2000
120.9
58.0
1982
76.1
36.5
Jan 2017*
208.5
100.0
100.0
1999
117.6
56,4
1981
70.0
33.6
July 2016
207.3
99.4
1998
115.1
55.2
1980
62.9
30.2
2015
206.2
98.9
1997
112.8
54.1
1979
57.8
27.7
2014
204.9
98.3
19%
110.2
52.9
1978
53.5
25.7
2013
201.2
96.5
1995
107.6
51.6
1977
49.5
23.7
2012
194.6
93.3
1994
104.4
50,1
1976
46.9
22.5
2011
191.2
91.7
1993
101.7
48,8
1975
44.8
21.5
2010
183.5
88.0
1992
99.4
47,7
1974
41.4
19.9
2009
180.1
86.4
1991
96.8
46.4
1973
37.7
18.1
2008
180.4
86.5
1990
94.3
45.2
1972
34.8
16.7
2007
169.4
81.2
1989
92.1
44.2
1971
32.1
15.4
2006
162.0
77.7
1988
89.9
43.1
1970
28.7
13.8
2005
151.6
72.7
1987
87.7
42,1
1969
26.9
12.9
2004
143.7
68.9
1986
84.2
40.4
1968
24.9
11.9
2003
132.0
63.3
1985
82.6
39.6
1967
23.5
11.3
Source: (RSMeans, 2017).
Figure 3-1. RSMeans Historical Cost Indexes
3.2.2 Unit Construction and Labor Costs
As mentioned in Section 2, ERG developed the purchased equipment and annual cost
results by unit process to allow for consistent presentation alongside results of the LCA model
and use in the LCCA. ERG used CAPDETWorks™ Version 3.0 (Hydromantis, 2014), a
software package designed for estimating the cost of wastewater treatment configurations, to
calculate the unit process costs for each wastewater treatment configuration. Each of the
wastewater treatment configurations used the same influent wastewater composition and flow
rate discussed in Section 1.2.2 and presented in Table 1-3.
CAPDETWorks1M includes default unit construction and labor costs that are used to
calculate the purchased equipment and annual costs. ERG reviewed the CAPDETWorks™
default unit construction and labor costs against those used in Striking the Balance Between
Nutrient Removal in Wastewater Treatment and SustainabiHty (Falk et al, 2011). The most
notable differences were for wall and slab concrete, and construction labor rate. For wall and
slab concrete, ERG used the average of the costs from CAPDETWorks1'1 and Striking the
Balance Between Nutrient Removal in Wastewater Treatment and Sustainability (Falk et al,
2011), as presented in Table 3-1.
To compute the actual index based on Jan. 1,2017 = 100, divide uie historical
cost index for a particular year by die actual Jan. 1,2017 construction cost index
Space has been left to advance the index figures as the year progresses.
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Section 3: Life Cycle Cost Analysis Methodology
Table 3-1. Unit Construction and Labor Costs
I nil (onslriiclion (osl
( AI'DI I Works'"
Doliiull ( osl (S/and)
l-'.ilk ol ill. 2011 ( osl
(S/cuul)
A\er;i;ie ( osl (S/cuul)
Wall Concrete
350
750
550
Slab Concrete
650
1,250
950
For the construction labor rate, ERG used the average of seven labor rates for
construction activities relevant to construction of a WWTP from the May 2016 National
Industry-Specific Occupational Employment and Wage Estimates for NAICS 221300 - Water,
Sewage and Other Systems (U.S. DOL, 2017). The seven labor categories that ERG used and
their labor rates in 2016 $ were:
• First-Line Supervisor of Construction Trades: $34.38/hr
• Construction Laborers: $17.88/hr
• Construction Equipment Operators: $23.12/hr
• Electricians: $31.60/hr
• Pipelayers, Plumbers, Pipefitters, and Steamfitters: $22.16/hr
• Construction Trades Helpers: $15.91 /hr
• Other Construction and Related Workers: $21,91/hr
The resulting average labor rate is $23.85/hr in 2016 $, which is $23.58/hr in 2014 $
using Equation 1 in Section 3.2.1. The U.S. DOL wages do not include overhead to account for
employee benefits. ERG assumed that contractors would be used for the construction and applied
a 2.1 private industry (i.e., contractors) multiplier (consultant multipliers typically range from 2-
2.2), resulting in an average construction labor rate of $49.51/hr. ERG rounded the construction
labor rate to $50/hr for use in this study.
3.2.3 Unit Process Costs
As mentioned in Section 2, ERG developed the purchased equipment and annual cost
results by unit process to allow for consistent presentation alongside results of the LCA model
and use in the LCCA. ERG used CAPDETWorks™ Version 3.0 (Hydromantis, 2014), a
software package designed for estimating the cost of wastewater treatment configurations, to
calculate the unit process costs for each wastewater treatment configuration. Each of the
wastewater treatment configurations used the same influent wastewater composition and flow
rate discussed in Section 1.2.2 and presented in Table 1-3.
CAPDETWorks™ includes all of the unit processes included in the nine wastewater
treatment configurations for this study with the exception of:
• Dechlorination. Included in all nine wastewater treatment configurations.
• Fermentation. Included in:
— Level 3-1 B5
— Level 3-2 MUCT
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Section 3: Life Cycle Cost Analysis Methodology
— Level 4-1 B5/Denit
— Level 5-1 B5/R0
— Level 5-2 MBR/RO
• 4-Stage Biological Nutrient Removal. Included in:
— Level 3-2 MUCT
— Level 4-2 MBR
• Methanol addition as a biological nutrient removal supplemental carbon source.
Included in Level 4-2 MBR.5
• Ultrafiltration. Included in Level 5-1 B5/RO.
• Reverse Osmosis and Antiscalant Chemical Injection Pretreatment. Included in:
— Level 5-1 B5/RO
— Level 5-2 MBR/RO
• Deep Well Injection. Included in:
— Level 5-B5/RO
— Level 5-2 MBR/RO
Details on the approach developed for these unit processes are presented in the following
subsections. The unit process costs for these unit processes were incorporated into the
CAPDETWorks™ output for comparison to the LCA model results and development of the total
plant costs.
Each of the nine wastewater treatment configurations was developed in
CAPDETWorks™. As part of this study, ERG reviewed the Municipal Nutrient Removal
Technologies Reference Document (U.S. EPA, 2008b), Nutrient Control Design Manual (U.S.
EPA, 2010), Striking the Balance Between Nutrient Removal in Wastewater Treatment and
Sustainability (Falk et al., 2011), Wastewater Engineering: Treatment and Resource Recovery
(Tchobanoglous et al., 2014), and additional EPA wastewater treatment process fact sheets to
confirm that the CAPDETWorks™ default design values were appropriate for use for this study.
Based on our review, ERG used the CAPDETWorks™ default design values for the unit
processes below that are included in one or more of the wastewater treatment configurations.
Appendix E. 1 includes the key parameters and default design values for the unit processes that
were modeled using the CAPDETWorks™ default design values. For the remaining unit
processes below, ERG revised the CAPDETWorks™ default design values. See Appendix E. 1
for the details on the revised default design values. Note that ERG used these design values in
the initial CAPDETWorks™ model for each wastewater treatment configuration. ERG then
revised some of the design values to eliminate errors in CAPDETWorks™ (e.g., subsequent unit
process designs were outside recommended design values) and achieve the effluent wastewater
objectives for each of the treatment levels. The final design values used for each wastewater
5 Methanol addition is also required for Level 2-2 AS3 for the denitrification - suspended growth unit process and
Level 4-1 B5/Denit and Level 5-1 B5/RO for the denitrification filters. However, CAPDETWorks™ includes the
methanol addition for these unit processes.
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Section 3: Life Cycle Cost Analysis Methodology
treatment configuration are included in the final CAPDETWorks™ cost output discussed in
Section 5.
• Default Design Values Used:
— Membrane Bioreactor
— Sand Filter
— Centrifugation - Sludge
• Design Values Revised:
— Preliminary Treatment - Screening
— Preliminary Treatment - Grit Removal
— Primary Clarifier
— Plug Flow Activated Sludge
— Biological Nutrient Removal 3/5 Stage
— Denitrification - Suspended Growth
— Denitrification - Attached Growth
— Nitrification - Suspended Growth
— Chemical Phosphorus Removal
— Secondary Clarifier
— Chlorination
— Gravity Thickener
— Anaerobic Digestion - Sludge
— Haul and Landfill - Sludge
ERG updated the CAPDETWorks™ default anaerobic digestion energy costs for all nine
wastewater treatment configurations to rely on natural gas rather than using the produced gas for
the reasons discussed in Section 3.2.3.8. ERG also determined that the CAPDETWorks™ default
electricity cost of $0.10/kWh was appropriate for use for this study based on the national average
electricity price as of May 2014 (U.S. EIA, 2015). The 2014 electricity costs match the 2014-
dollar basis discussed in Section 3.2.1.
3.2.3.1 Dechlorination
Dechlorination is not a unit process available in CAPDETWorks™. Therefore, ERG
developed a costing methodology for dechlorination based on the CAPDETWorks™
chlorination unit process and vendor costs, which was then incorporated into the
CAPDETWorks™ outputs to calculate the total costs of all nine wastewater treatment
configurations.
Capital cost elements for dechlorination include the dechlorination contact tank,
dechlorination building, chemical storage building, sodium bisulfite liquid feed system, and
miscellaneous items (e.g., grass seeding, site cleanup, piping). The dechlorination contact tank,
dechlorination building, chemical storage building, and miscellaneous items are similar to the
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Section 3: Life Cycle Cost Analysis Methodology
components included in the CAPDETWorks™ chlorination unit process. As a result, ERG
estimated costs for these capital cost elements using the CAPDETWorks™ chlorination unit
process with design values for contact time and chemical dose to simulate dechlorination. ERG
estimated purchase costs for the sodium bisulfite liquid feed system based on cost information
provided by a vendor.
Operating and maintenance cost elements for dechlorination include operating labor,
maintenance labor, materials and supplies costs, sodium bisulfite chemicals, and energy. ERG
estimated operating and maintenance labor, materials, and supplies costs using the
CAPDETWorks™ chlorination unit process with design values for contact time and chemical
dose to simulate dechlorination. Estimated energy costs for the sodium bisulfide feed system
pump is based on energy usage provided by the vendor and the energy rate used for the
CAPDETWorks™ costing ($0.10/kWh). Sodium bisulfite chemical costs are estimated using the
following sodium bisulfite dosages with the chlorination effluent flow rate provided from the
CAPDETWorks™ chlorination unit process:
• 1.5 mg/L for Levels 1, 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2 wastewater treatment
configurations.
• 3.0 mg/L for Levels 5-1 and 5-2 that includes 1.5 mg/L for the dechlorination
requirement and 1.5 mg/L for the reverse osmosis pretreatment requirement.
ERG used a 40% sodium bisulfite solution cost of $344/ton in 2010 $ as provided by a
vendor, converted to 2014 $ using the methodology presented in Section 3.2.1.
Detailed descriptions of the dechlorination costing approach are provided in Appendix
E.2, including all cost bases, assumptions, and calculations.
3.2.3.2 Fermentation
Fermentation is not a unit process available in CAPDETWorks™. However, as detailed
in Municipal Nutrient Removal Technologies Reference Document (EPA, 2008), a fermenter is
an oversized gravity thickener with additional piping and mixers. In the Municipal Nutrient
Removal Technologies Reference Document, the fermenter was modeled using the
CAPDETWorks™ gravity thickener module and escalating the results by 50 percent (EPA,
2008). ERG used best professional judgement to confirm this approach and modeled the gravity
thickener unit process in CAPDETWorks™ and multiplied the capital, operating, and
maintenance costs by 1.5 to account for the larger size, additional equipment, and associated
increased energy.
3.2.3.3 4-Stage Biological Nutrient Removal (Modified UCT and 4-Stage Bardenpho)
CAPDETWorks™ does not include a 4-stage biological nutrient removal (BNR) unit
process, like those included in Level 3-2 as a 4-stage Modified University of Cape Town (UCT)
and Level 4-2 as a 4-stage Bardenpho with membrane bioreactor. However, CAPDETWorks™
includes 3-stage and 5-stage BNR unit processes. For each of the wastewater treatment
configurations with 4-stage BNR unit processes, ERG developed two separate
CAPDETWorks™ models that included all of the same unit processes, except model 1 included
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Section 3: Life Cycle Cost Analysis Methodology
the 3-stage BNR unit process and model 2 included the 5-stage BNR unit process. ERG
combined the CAPDETWorks™ output from models 1 and 2 to estimate the capital, operating,
and maintenance costs for the 4-stage BNR units, as described below.
Capital cost elements for BNRs include the BNR tank, blower system, internal recycle
pumps, and sludge recycle pumps. Operating and maintenance cost elements for BNRs include
operating labor, maintenance labor, materials costs, and energy.
For the 4-stage Modified UCT in Level 3-2, ERG modeled the 3-stage version using a 3-
stage BNR with two internal recycle pumps to reflect the multiple recycles in the Modified UCT.
ERG used the Level 3-1 wastewater treatment configuration for the 5-stage version. The capital
costs for the BNR tanks, blower system, and BNR sludge recycle pumps were averaged for the
3- and 5-stage models, while the capital costs from the 3-stage model were used for the BNR
internal recycle pumps. The capital costs for all other unit processes in these models had the
same capital costs. The operating and maintenance costs for the BNR tank, BNR sludge recycle
pumps, and blower system were averaged for the 3- and 5-stage models; the 3-stage model costs
were used for the BNR internal recycle pumps; and the 5-stage model costs were used for the
chemical phosphorus removal and alum feed system because the Modified UCT will achieve
biological phosphorus removal closer to the 5-stage BNR model and, therefore, would require
less alum to achieve the target effluent phosphorus concentration. The operating and
maintenance costs for all other unit processes in these models had negligible differences between
the 3- and 5-stage models.
For the 4-stage Bardenpho with membrane bioreactor, ERG modeled the 3-stage model
using the 3-stage BNR with membrane bioreactor and 5-stage model using the 5-stage BNR with
membrane bioreactor. The capital, operating, and maintenance costs for the BNR tank, BNR
internal recycle pumps, and BNR sludge recycle pumps were averaged for the 3- and 5-stage
models. The capital costs for all other unit processes in these models had negligible differences
in the capital costs. The operating and maintenance costs for the chemical phosphorus removal
and alum feed system from the 5-stage model were used because the 4-stage Bardenpho with
membrane bioreactor will achieve biological phosphorus removal closer to the 5-stage BNR
model and, therefore, would require less alum to achieve the target effluent phosphorus
concentration. The operating and maintenance costs for all other unit processes in these models
had negligible differences between the 3- and 5-stage models.
Details on how the 3- and 5-stage models were combined for the Level 3-2 and Level 4-2
wastewater treatment configurations are included in Section 5.
3.2.3.4 Methanol Addition for Biological Nutrient Removal Supplemental Carbon for
Level 4-2 MBR
Biological nitrogen removal requires an adequate supply of carbon for denitrification.
CAPDETWorks™ includes an external carbon source (i.e., methanol addition) to:
• Level 2-2 AS3's denitrification - suspended growth
• Level 4-1 B5/Denit's denitrification filter
• Level 5-1 B5/RO's denitrification filter
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Section 3: Life Cycle Cost Analysis Methodology
ERG included fermenters to provide an internal carbon source for biological nitrogen
removal occurring in the Bardenpho and Modified University of Cape Town reactors in:
• Level 3-1 B5
• Level 3-2 MUCT
• Level 4-1 B5/Denit
• Level 5-1 B5/RO
• Level 5-2 MBR/RO
However, there is no internal carbon source for denitrification in Level 4-2 MBR. As a
result, the Level 4-2 wastewater treatment configuration required methanol addition from an
external carbon source. CAPDETWorks™ Version 3.0 does not include a stand-alone methanol
addition unit process. Therefore, ERG developed a costing methodology for supplemental
methanol addition based on the effluent nitrate target in CAPDETWorks™ denitrification filter
unit process, which was then incorporated into the CAPDETWorks™ outputs to calculate the
total costs for the Level 4-2 wastewater treatment configuration. CAPDETWorks™ calculates
the methanol addition in the denitrification filter unit process based on 3 mg methanol per mg
nitrate removed (Hydromantis, 2014). ERG determined the CAPDETWorks™ effluent nitrate
target for the denitrification filter unit process as 1.95 mg/L nitrate based on the required
denitrification to achieve the 3 mg/L total nitrogen for Level 4 (total Kjeldahl nitrogen effluent is
1.05 mg/L).
Capital cost elements for methanol addition include a methanol liquid feed system,
chemical storage area, and miscellaneous items (e.g., grass seeding, site cleanup, piping). The
methanol liquid feed system is the same as the methanol liquid feed system included in
CAPDETWorks™ denitrification filter unit process with design values for the effluent nitrate
target to simulate the denitrification requirement. CAPDETWorks™ does not include separate
methanol storage area costs or miscellaneous items in the denitrification filter unit process. As
such, ERG assumed that these costs are minimal and would be accounted for in the 4-stage
Bardenpho costs.
Operating and maintenance cost elements for methanol addition include operating labor,
maintenance labor, materials and supplies costs, methanol chemicals, and energy. ERG estimated
methanol chemicals using the CAPDETWorks™ denitrification filter unit process with design
values for the effluent nitrate target to simulate the denitrification requirement.
CAPDETWorks™ does not include separate operating labor, maintenance labor, materials and
supplies costs, and energy costs for the methanol system in the denitrification filter unit process.
As a result, ERG assumed that these costs are minimal and would be accounted for in the 4-stage
Bardenpho operating and maintenance costs. Methanol chemical costs are based on the
CAPDETWorks™ default cost of $0.60/lb methanol in 2014 $ (Hydromantis, 2014).
Detailed descriptions of the methanol addition for biological nutrient removal
supplemental carbon are provided in Appendix E.4, including all cost bases, assumptions, and
calculations.
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Section 3: Life Cycle Cost Analysis Methodology
3.2.3.5 Ultrafiltration
Ultrafiltration is not a unit process available in CAPDETWorks™ Version 3.0.
Therefore, ERG developed a costing methodology for ultrafiltration outside of
CAPDETWorks™ and then incorporated the cost elements into the CAPDETWorks™ outputs to
calculate the total cost of each wastewater treatment configuration that includes ultrafiltration
(Level 5-1 B5/RO).
Capital cost elements for ultrafiltration include the membrane filtration system
(membrane equipment and all appurtenances such as feed pumps, backwash system, and clean-
in-place system) and a building to house the membrane filtration system. ERG estimated
purchased equipment costs for the membrane filtration system based on cost information
provided by a vendor. ERG estimated capital costs for the building using a CAPDETWorks™
building unit total capital cost of $110/square foot and an estimated building footprint provided
by the vendor.
Operating and maintenance cost elements for ultrafiltration include operating labor,
maintenance labor, materials costs (assumed a 7-year membrane life), chemicals (membrane
cleaning), and energy. Operating and maintenance labor costs were estimated using a
combination of information provided by the vendor, best professional judgement, and labor rates
from CAPDETWorks™. Membrane replacement and chemicals costs are based on cost
information provided by the vendor. Estimated energy usage for the membrane filtration system
is based on a combination of information provided by the vendor and literature sources. ERG
then calculated estimated energy costs by multiplying the estimated energy usage by the energy
rate used for the CAPDETWorks™ costing ($0.10/kWh).
Detailed descriptions of our ultrafiltration costing approach are provided in Appendix
E.5, including all cost bases, assumptions, and calculations.
3.2.3.6 Reverse Osmosis (RO)
RO is not a unit process available in CAPDETWorks™ Version 3.0. Therefore, ERG
developed a costing methodology for RO outside of CAPDETWorks™ and then incorporated the
cost elements into the CAPDETWorks™ outputs to calculate the total cost of for each
wastewater treatment configuration that includes RO (Level 5-1 B5/RO and Level 5-2
MBR/RO).
Capital cost elements for RO include the RO system (membrane equipment and all
appurtenances such as feed pumps, backwash system, and clean-in-place system), a chlorine gas
feed system, a dechlorination feed system, an antiscalant feed system, a brine surge sump, and a
building to house the RO system. ERG estimated purchased equipment costs for the RO system
based on cost information provided by a RO vendor. ERG estimated capital costs for the building
using a CAPDETWorks™ building unit total capital cost of $110/square foot and an estimated
building footprint provided by the RO vendor. Costs for the chlorination feed system are
included within the CAPDETWorks™ chlorination module discussed previously in this section.
Costs for the dechlorination and antiscalant feed systems were estimated based on cost
information provided by a feed system vendor. For the brine surge sump, ERG first estimated the
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Section 3: Life Cycle Cost Analysis Methodology
required sump volume, assuming a 60-minute hydraulic residence time, based on best
professional judgement. ERG then estimated the brine sump total capital costs using online RS
Means Building Construction Cost Data.
Operating and maintenance cost elements for RO include operating labor, maintenance
labor, materials costs (assumed a 4-year membrane life), chemicals (membrane cleaning,
antiscalant, chlorine gas, and sodium bisulfite dechlorination), and energy. Operating and
maintenance labor costs were estimated using a combination of information provided by the RO
vendor, best professional judgement, and labor rates from CAPDETWorks™. Membrane
replacement and membrane cleaning chemical costs are based on cost information provided by
the vendor. Antiscalant chemical costs were estimated using the dosage rate provided by the RO
vendor and a chemical cost provided by a chemical vendor. Chlorine gas and sodium bisulfite
chemical costs are included within the CAPDETWorks™ chlorination module and the
supplemental dechlorination module developed by ERG discussed previously in this section.
Estimated energy usage for the RO system is based on a combination of information provided by
the RO vendor and literature sources; estimated energy usage for the dechlorination and
antiscalant feed systems is based on information provided by the chemical feed system vendor.
ERG then calculated estimated RO and feed system energy costs by multiplying the estimated
energy usage by the energy rate used for the CAPDETWorks™ costing ($0.10/kWh).
Detailed descriptions of our RO system costing approach are provided in Appendix E.6,
including all cost bases, assumptions, and calculations.
3.2.3.7 Deep Injection Well
Deep well injection is not a unit process available in CAPDETWorks™ Version 3.0.
Therefore, ERG developed a costing methodology for deep well injection outside of
CAPDETWorks™ and then incorporated the cost elements into the CAPDETWorks™ outputs to
calculate the total cost of each wastewater treatment configuration that includes brine disposal
(Level 5-1 B5/RO and Level 5-2 MBR/RO).
Capital cost elements for deep well injection include injection well pumps, a building to
house the injection pumps and electrical control panel and drilling the underground injection
well. Purchase costs for the injection well pumps were based on information provided by a pump
vendor; pump freight costs were estimated based on information from an equipment supply
vendor. ERG estimated capital costs for the building using a CAPDETWorks™ building unit
total capital cost of $110/square foot and an estimated building footprint developed based on best
professional judgement. ERG estimated costs for drilling a new underground injection well
based on cost information provided by a waste disposal vendor.
Operating and maintenance cost elements for deep well injection include operating labor,
maintenance labor, materials costs, and energy. Operating and maintenance labor costs were
estimated using a combination of best professional judgement and labor rates from
CAPDETWorks™. Materials costs were estimated as 2 percent of injection well pump purchase
cost, based on CAPDETWorks™ methodology. ERG estimated energy usage for the injection
well pumps using the pump HP rating and assuming continuous operation. ERG then calculated
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Section 3: Life Cycle Cost Analysis Methodology
estimated injection well pump energy costs by multiplying the estimated energy usage by the
energy rate used for the CAPDETWorks™ costing ($0.10/kWh).
Detailed descriptions of our deep well injection costing approach are provided in
Appendix E.7, including all cost bases, assumptions, and calculations.
3.2.3.8 Anaerobic Digester Natural Gas Usage
CAPDETWorks™ assumes that the gas produced by the anaerobic digester is used to
supply heat to the anaerobic digester. If the digester gas produced is insufficient,
CAPDETWorks™ uses natural gas for the difference. Because most WWTPs flare the digester
gas, ERG revised the energy calculations for the anaerobic digester to assume that all the heat
required was provided by natural gas using Equation 2 and Equation 3, and that all digester gas
produced was flared.
Energy Costs = Electricity Cost + Total Natural Gas Required x Natural Gas Cost
Equation 2
where:
Energy Costs (2014 $/yr) = Energy cost to run the anaerobic digester for a year
Electricity Cost (2014 $/yr) = Electricity cost from CAPDETWorks™ to run the
anaerobic digester for a year
Total Natural Gas Required (1,000 cuft/yr) = Natural gas required to heat the anaerobic
digester (see Equation 3)
Natural Gas Cost (2014 $/l,000 cuft)= $15,500/1,000 cuft
Heat Required
Total Natural Gas Required= ———— ——-— ———
Boiler Efficiency x Heat Exchanger Efficiency
Hours per Year Conversion TT . _
x x Unit Conversion
Natural Gas Heating Value
Equation 3
where:
Total Natural Gas Required (1,000 cuft/yr) = Natural gas required to heat the anaerobic
digester
Heat Required (BTU/hr) = Heat required to heat the anaerobic digester
Boiler Efficiency (%) = 80%
Heat Exchanger Efficiency (%) = 90%
Hours per Year Conversion (hr/yr) = 8,760 hr/yr
Natural Gas Heating Value (BTU/cuft) = 1,000 BTU/cuft
Unit Conversion (1,000 cuft/cuft) = 1,000 cuft (with 1,000 cuft as the unit)/ 1,000 cuft
(with cuft as the unit)
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Section 3: Life Cycle Cost Analysis Methodology
3.3 LCCA
LCCA enables a total cost comparison of the nine wastewater treatment configurations
including all of the relevant costs that occur throughout the life of the treatment alternatives. The
total plant costs are presented in two ways: 1) total capital costs along with total annual costs
(see Section 3.3.1) and 2) net present value (see Section 3.3.2). The net present value is a method
to combine one-time capital costs and periodic (annual) operating and maintenance costs into
one value for direct comparison of costs for alternative wastewater treatment configurations.
3.3.1 Total Capital and Total Annual
The total capital costs include the purchased equipment, direct costs, and indirect costs.
The purchased equipment includes the cost to purchase the equipment and freight to get the
equipment to the WWTP site. The direct costs are costs incurred as a direct result of installing
the WWTP. For this study, the direct costs include mobilization, site preparation, site electrical,
yard piping, instrumentation and control, and lab and administration building. The indirect costs
are non-direct costs incurred as a result of installing the WWTP. For this study, the indirect costs
include land, miscellaneous items, legal costs, engineering design fee, inspection costs,
contingency, technical, interest during construction, and profit. The total capital costs are
calculated using Equation 4 for each wastewater treatment configuration.
Total Capital Costs = Purchased Equipment Costs + Direct Costs
+ Indirect Costs
Equation 4
where:
Total Capital Cost (2014 $) = Total capital costs
Purchased Equipment Costs (2014 $) = Costs to purchase the equipment for the WWTP,
including ancillary equipment and freight costs (see the following subsection for details)
Direct Costs (2014 $) = Costs incurred as a direct result of installing the WWTP (see the
following subsection for details)
Indirect Costs (2014 $) = Costs for all non-direct costs incurred as a result of
installing the WWTP (see the following subsection for details)
The total annual costs (often referred to as O&M) include the operation and maintenance
labor, materials, chemicals, and energy. CAPDETWorks™ includes the periodic replacement of
equipment parts (e.g., membranes, filter media, pumps) in the materials' annual costs. ERG used
the same methodology for the membrane replacement costs for ultrafiltration and RO, which are
detailed in Sections 3.2.3.4 and 3.2.3.6. ERG calculated total annual costs using Equation 5.
Total Annual Costs = Operation Costs + Maintenance Costs + Materials Costs
+ Chemical Costs + Energy Costs
Equation 5
KP-C-16-003; WA 2^37
3-15
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Section 3: Life Cycle Cost Analysis Methodology
where:
Total Annual Costs (2014 $/year) = Total annual operation and maintenance costs
Operation Costs (2014 $/year) = Labor costs for manual labor required to operate the
WWTP for a year, including operation, administrative, and laboratory labor
Maintenance Costs (2014 $/year) = Labor costs for manual labor required to maintain the
WWTP for a year
Materials Costs (2014 $/year) = Materials costs for operation and maintenance of the
WWTP for a year, including replacement equipment
Chemical Costs (2014 $/year) = Chemical costs for chemicals required for WWTP
operation (e.g., alum, polymer) for a year
Energy Costs (2014 $/year) = Electricity costs to run the WWTP for a year
CAPDETWorks™ calculates the operation and maintenance costs based on labor
required and average salary for each job description: administrative, operation, maintenance, and
laboratory. The administrative and laboratory labor hours are based on the WWTP flow rate,
while the operation and maintenance hours are calculated for each process based on factors like
the flow rate, number of units in each process, wastewater characteristics (e.g., total dissolved
solids), and process design factors (e.g., required air rate). CAPDETWorks™ calculates the
materials costs for operation and maintenance for each unit process based on factors like flow
rate, unit capacity, and total construction cost. CAPDETWorks™ calculates the chemical costs
based on the specific unit processes and the dosage rate. CAPDETWorks™ calculates the energy
costs using the energy consumption requirements for the unit processes and $0.10/kWh. As of
May 2014, the average price of electricity for all sectors was $0.1023/kWh as published by the
U.S. Energy Information Administration (US EIA, 2015). As a result, ERG used the
CAPDETWorks™ default electricity price, which is reflective of 2014 to match the 2014-dollar
basis discussed in Section 3.2.1.
ERG used the CAPDETWorks™ total annual costs for unit processes in
CAPDETWorks™. For unit processes not in CAPDETWorks™, ERG calculated total annual
costs including the same components as CAPDETWorks™, as applicable for the specific unit
process.
Purchased Equipment Costs
ERG costed the purchased equipment primarily using CAPDETWorks™, as described in
Section 3.2.2 above. However, certain unit processes comprising the system configurations are
not available in CAPDETWorks™. For these unit processes, ERG developed costs outside of
CAPDETWorks™ and then incorporated these cost elements into the CAPDETWorks™ outputs
to calculate the total purchased equipment costs for each wastewater treatment configuration, as
presented in Equation 6.
Purchased Equipment Costs = £ Unit Process Equipment Costs
Equation 6
EP-C-I6-QQ3; WA 2^37
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Section 3: Life Cycle Cost Analysis Methodology
where:
Purchased Equipment Costs (2014 $) = Costs to purchase the equipment for the WWTP,
including ancillary equipment and freight costs
Unit Process Equipment Costs (2014 $) = Costs to purchase the equipment for each unit
process at the WWTP, including costs from CAPDETWorks™ and developed outside of
CAPDETWorks™ (see Section 3.2.2 for details)
Direct Costs
CAPDETWorks™ includes direct costs for mobilization, site preparation, site electrical,
yard piping, instrumentation and control, and lab and administration building. These direct costs
account for the portions of the wastewater treatment configuration that are not directly associated
with a unit process. CAPDETWorks™ calculates direct costs proportional to the WWTP flow
based on cost curves generated from EPA's Construction Costs for Municipal Wastewater
Treatment Plants: 1973-1978 (U.S. EPA, 1980). Using this approach would not account for
differences in the direct costs due to the increasing complexity of the nine wastewater treatment
configurations. The CAPDETWorks™ approach is also inconsistent with standard engineering
costing that calculates direct costs as a percentage of purchased equipment costs (Peters and
Timmerhaus, 1991; Falk et al., 2011). As a result, ERG used the CAPDETWorks™ results from
the Level 1 wastewater treatment configuration with the CAPDETWorks™ default unit process
inputs to calculate direct cost factors for each direct cost element as a percentage of total
purchased equipment cost as presented in Equation 7. Because CAPDETWorks™ calculates the
same direct costs for all nine wastewater treatment configurations, calculating the direct cost
factors using the lowest purchased equipment costs of the nine wastewater treatment
configurations (i.e., Level 1), will result in the highest direct costs factors. ERG confirmed the
calculated direct cost factors were reasonable based on other engineering sources (Falk et al.,
2010).
„ _ Level 1 Direct Cost
Direct Cost Factor =
Level 1 Purchased Equipment Cost
Equation 7
where:
Direct Cost Factor (%) = Direct cost factor for each direct cost element, see Table 1
below
Level 1 Purchased Equipment Cost (2014 $) = $19,600,000 (see Appendix E.8)
Level 1 Direct Cost (2014 $) = see Table 3-2 below
Table 3-2. Direct Cost Factors
Diivcl Cosl l.kiiH'iils
l.c\d 1 Direct Costs (2014 M
Direct Cosl l-.iclor ('!»)
Mobilization
$818,000
4%
Site Preparation
$1,090,000
6%
Site Electrical
$2,360,000
12%
KP-C-16-003; WA 2^37
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Section 3: Life Cycle Cost Analysis Methodology
Table 3-2. Direct Cost Factors
Diivcl Cosl I k'iiH'iKs
l.c\cl 1 Diivcl ( oMs (2014 S)
Diivcl Cosl l";iclor ("»)
Yard Piping
$1,550,000
8%
Instrumentation and Control
$1,240,000
6%
Lab and Administration Building
$1,930,000
10%
Source: Appendix E.8.
ERG applied the direct cost factors from Table 3-2 to the total purchased equipment cost
for each of the nine wastewater treatment configurations using Equation 8 to calculate the direct
costs for each direct cost element.
Direct Cost = Direct Cost Factor * Purchased Equipment Cost
Equation 8
where:
Direct Cost (2014 $) = Direct cost for each direct cost element
Direct Cost Factor (%) = Direct cost factor for each direct cost element, see Table 3-2
Purchased Equipment Cost (2014 $) = Total purchased equipment cost for each
wastewater treatment configuration (see Equation 6)
Indirect Costs
CAPDETWorks™ includes indirect costs for land, miscellaneous items, legal costs,
engineering design fee, inspection costs, contingency, technical, interest during construction, and
profit. ERG used Equation 9 to calculate the total indirect costs.
Indirect Costs = Land Cost + Remaining Indirect Costs
+ Interest During Construction
Equation 9
where:
Indirect Costs (2014 $) = Costs for all non-direct costs incurred as a result of installing
the WWTP
Land Cost (2014 $) = Total cost for the land required for the WWTP, see Equation 10
below
Remaining Indirect Costs (2014 $) = Indirect costs associated with miscellaneous costs,
legal costs, engineering design fee, inspection costs, contingency, technical, and profit,
see Equation 11 below
Interest During Construction (2014 $) = Interest paid during construction, see Equation
12 below
EP-C-I6-QQ3; WA 2^37
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Section 3: Life Cycle Cost Analysis Methodology
ERG used CAPDETWorks™ land costs, which are calculated using Equation 10.
Land Cost = Treatment Area x Land Unit Cost
Equation 10
where:
Land Cost (2014 $) = Total cost for the land required for the WWTP
Treatment Area (acres) = Required treatment area for the WWTP based on the unit
processes costed from CAPDETWorks™6
Land Unit Cost (2014 $/acre) = $20,000/acre, the CAPDETWorks™ default land unit
cost, (Hydromantis, 2014)
For the remaining indirect costs ERG used contingency cost percentage based on cost
estimate recommended practices (ACCEI, 2016) and CAPDETWorks™' indirect cost
percentages (Table 3-3) to calculate indirect costs as a percentage of purchased equipment cost
and direct construction costs for each wastewater treatment configuration as presented in
Equation 11.
Remaining Indirect Costs = Indirect Cost Factor
x (Purchased Equipment Cost + Direct Cost)
Equation 11
where:
Remaining Indirect Cost (2014 $) = Indirect costs associated with miscellaneous costs,
legal costs, engineering design fee, inspection costs, contingency, technical, and profit
Indirect Cost Factor (%) = Indirect cost factor for each indirect cost element, see Table
3-3
Purchased Equipment Cost = Total purchased equipment cost (see Equation 6)
Direct Cost (2014 $) = Total direct costs (see Equation 8)
Table 3-3. Indirect Cost Factors
IndiiTCl ( osl IHoiiKMils
Indiivcl ( osl l";ic(or ("i>)
Miscellaneous Costs
5%
Legal Costs
2%
Engineering Design Fee
15%
6 All unit processes in the wastewater treatment configurations for Levels 1 through 4 are included in
CAPDETWorks™ land area calculations. For the Level 5 wastewater treatment configurations, ERG determined
that the land requirements for the non-CAPDETWorks™ unit processes (i.e., Level 5-1: ultrafiltration, reverse
osmosis, and deep injection well; Level 5-2: reverse osmosis and deep injection well) was minimal and would fit
within the CAPDETWorks™ land area.
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Section 3: Life Cycle Cost Analysis Methodology
Table 3-3. Indirect Cost Factors
Indirect ( osl 1!lemon(n
Indirect ( osl l";ic(or (";•)
Inspection Costs
2%
Contingency
20%
Technical
2%
Profit
15%
Source: Hydromantis, 2014; AACEI, 2016.
For the interest during construction, ERG used Equation 12.
Interest During Construction = (Purchased Equipment Cost + Direct Costs + Select Indirect Costs)
„ . _ . , Interest Rate During Construction
x Construction Period x
2
Equation 12
where:
Interest During Construction (2014 $) = Interest paid during construction
Purchased Equipment Cost (2014 $) = Total purchased equipment cost for each
wastewater treatment configuration (see Equation 6)
Direct Costs (2014 $) = Total direct costs (see Equation 8)
Select Indirect Costs (2014 $) = Indirect costs, including miscellaneous items, legal costs,
engineering design fee, inspection costs, contingency, and technical
Construction Period (years) = 3 years based on CAPDETWorks™ default construction
period (Hydromantis, 2014)
Interest Rate During Construction (%) = Interest rate during construction
ERG used 3% and 5% interest rates during construction, which are the same values ERG
used for the discount rates discussed in Section 3.3.2. The 3% interest rate represents a
conservative interest rate for a State Revolving Fund (SRF) loan as the SRF average loan rate
was 1.7% in April 2016 (U.S. EPA, 2016a). The 5% interest rate represents a worse-case
scenario reflective of rates that WWTPs in poor financial shape, but still able to borrow, would
be able to obtain.
3.3.2 Net Present Value
ERG calculated the net present value using Equation 13. This equation assumes that the
only value remaining in the WWTP at the end of the planning period is in the land, which
increases in value by 3% over the planning period using CAPDETWorks™' approach.
NPV = f^+.y?p x (Amortized Construction Cost + Total O&M Cost)
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Section 3: Life Cycle Cost Analysis Methodology
+ Land*(l-(103PV
Equation 13
where:
NPV (2014 $) = Net present value of all costs necessary to construct and operate the
WWTP
Amortized Construction Cost (2014 $/yr) = Total construction costs amortized over the
WWTP planning period, see Equation 14 below
Total O&M Costs (2014 $/yr) = Total annual operation and maintenance costs, see the
previous subsection
Land (2014 $) = Land costs from CAPDETWorks™ models for each wastewater
treatment configuration
i (%) = Real discount rate
PP (years) = WWTP planning period
1.03 = Factor to account for a 3% increase in land value over the WWTP planning period
ERG used 3% and 5% real discount rates, which are the same values ERG used to
calculate the interest during construction. See the indirect costs subsection within Section 3.3.1
for a discussion on the basis for the selected interest rates. The real discount rate approximates
the marginal pretax rate of return on an average investment in the private sector in recent years
and has been adjusted to eliminate the effect of expected inflation. As a result, ERG did not
adjust the construction or O&M costs for inflation. ERG used 20 years as the WWTP planning
period.
ERG calculated amortized construction costs using Equation 14.
Amortized Construction Cost = -12 x PMT ^, PP, Total Capital Cost, 0, 0 j
Equation 14
where:
Amortized Construction Cost (2014 $) = Total construction costs amortized over the
WWTP planning period
PMT = Excel® function that calculates the stream of equal periodic payments that has the
same present value as the actual stream of unequal payments over the project life at a
constant interest rate (for example, a mortgage converts the one-time cost of a house to a
stream of constant monthly payments)
i (%) = 3% and 5% discount rates
PP (years) = WWTP planning period (20 years)
Total Capital Cost (2014 $) = Total capital costs, see Equation 4
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Section 3: Life Cycle Cost Analysis Methodology
3.4 Data Quality
In accordance with the project's Quality Assurance Project Plan (QAPP) entitled Quality
Assurance Project Plan for Life Cycle and Cost Assessments of Nutrient Removal Technologies
in Wastewater Treatment Plants approved by EPA on March 25, 2015 (ERG, 2015c), ERG
collected existing data7 to develop cost estimates for the nine wastewater treatment
configurations in this study. As discussed in Section 3.1, the cost estimate data sources include
CAPDETWorks™ Version 3.0 (Hydromantis, 2014), EPA reports, peer-reviewed literature,
publicly available equipment costs from and communication with technology vendors, and
industry-accepted construction cost data and indices. ERG evaluated the collected information
for completeness, accuracy, and reasonableness. In addition, ERG considered publication date,
accuracy/reliability, and costs completeness when reviewing data quality. Finally, ERG
performed conceptual, developmental, and final product internal technical reviews of the costing
methodology and calculations for this study.
Table 3-4 presents the data quality criteria ERG used when evaluating collected cost data.
ERG documented the data quality for each data source for each criterion in a spreadsheet for
EPA's use in determining whether the cost data are acceptable for use. All of the references used
to develop the costs met all of the data quality criteria with the exceptions of EPA's Wastewater
Technology Fact Sheet - Dechlorination (U.S. EPA. 2000), EPA's Biosolids Technology Fact
Sheet - Gravity Thickening (U.S. EPA, 2003a), and EPA's Wastewater Technology Fact Sheet -
Screening and Grit Removal (U.S. EPA, 2003b). These references did not meet the criteria for
currency (up to date). ERG used the Wastewater Technology Fact Sheet - Dechlorination to
develop the contact time required to dechlorinate the residual chlorine. Although this EPA report
is not current, the contact time for dechlorination has not changed since the fact sheet was
published. ERG used the Biosolids Technology Fact Sheet - Gravity Thickening to revise the
gravity thickener default CAPDETWorks™ values for depth and standard cost for a 90 ft
diameter thickener. ERG used the Wastewater Technology Fact Sheet - Screening and Grit
Removal to revise the CAPDETWorks™ purchased equipment cost for the preliminary
treatment unit process (i.e., screening and grit removal). Although these EPA reports are not
current, ERG revised the default values based on feedback from Falk et al. (2017) that the
CAPDETWorks™ default values, designed in the 1970s, were no longer appropriate.
Table 3-4. Cost Data Quality Criteria
(„)u;ilil> ( rilcrioii: ( ns( l);il;i
IK'sc riplinn/lk-rinil ion
Current (up to date)
Report the time period of the data. Year of publication (or presentation, if a
paper presented at a conference) is 2005 or after.
Complete
Identify if all units are reported. Identify the cost per year basis reported. a
Representative
Report if the costs are for unit processes used in the selected nutrient
wastewater treatment configurations.
7 Existing data means information and measurements that were originally produced for one purpose that are
recompiled or reassessed for a different purpose. Existing data are also called secondary data. Sources of existing
data may include published reports, journal articles, LCI and government databases, and industry publications.
KP-C-16-003; WA 2^37
3-22
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Section 3: Life Cycle Cost Analysis Methodology
Table 3-4. Cost Data Quality Criteria
(„)iiiilil\ ( rilcriuii: ( osl l);il;i
Doscripl ioii/Doliiiil ion
Accurate/Reliable
Document the source of the data. Were the data (1) obtained from well-known
technical references for engineering design and cost information, as well as for
general cost factors (e.g., engineering, permitting, scheduling), or (2) from
selected vendors that are the leaders within their areas of expertise determined
based on the use of their technologies at municipal facilities that have well
designed and operated wastewater treatment systems?
a - See Section 3.2.1 for the calculation ERG used to convert all costs to a standard year basis using RSMeans
Construction Cost Index (RSMeans, 2017).
ERG developed the CAPDETWorks™ input files containing all the necessary
information and data required for the tool to execute the wastewater treatment designs and
engineering costing. All CAPDETWorks™ input files were reviewed by a team member
knowledgeable of the project, but who did not develop the input files. The reviewer ensured the
accuracy of the data transcribed into the input files, the technical soundness of methods and
approaches used (i.e., included all of the cost components and LCA inputs) and the accuracy of
the calculations (i.e., used the methodology in Section 3.3 to calculate the costs).
ERG developed the supplemental cost estimates for ultrafiltration, reverse osmosis, and
deep well injection in an Excel® Workbook. A team member knowledgeable of the project, but
who did not develop the Excel® workbook, reviewed the workbook to ensure the accuracy of the
data transcribed into the workbook, the technical soundness of methods and approaches used,
and the accuracy of calculations.
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Section 4: LCA Methodology
4. LCA Methodology
This chapter covers the data collection process, data sources, assumptions, methodology
and parameters used to construct the LCI model for this study. Following the LCI discussion,
details on the impact assessment are provided.
4.1 Life Cycle Inventory Structure
LCI data are the foundation of any LCA study. Every element included in the analysis is
modeled as its own LCI unit process entry (see Appendix G for an example). It is the connection
of LCI unit process data that constitutes the LCA model. A simplified depiction of a subset of
this structure for this study is shown in Figure 4-1. The overall system boundaries were
previously presented in Figure 1-1, and include all unit processes associated with plant
operations and disposal of sludge, not just those processes associated with nutrient removal. It is
not possible to display this type of figure for the entire LCA model, as each LCA model includes
thousands of connected unit process inputs and outputs. Each box in the figure represents an LCI
unit process. The full system is a set of nested LCIs where the primary process outputs, in red, of
one process serve as inputs, in blue, to another process. Within each nested level, there can be
flows both to and from the environment. Flows from the environment are written in black in
Figure 4-1 and are represented by the thin black arrows crossing the system boundary from
nature. Emissions to the environment are listed in green, and it is these flows that are tabulated in
the calculation of environmental impacts. Intermediate inputs are shown in blue text.
Intermediate inputs are those that originate from an extraction or manufacturing process within
the supply-chain.
The distinction between the foreground and background systems is not a critical one. The
foreground system tends to be defined as those LCIs that are the focus of the study. In this case,
that is the WWTP itself. Foreground information was drawn directly from the CAPDETWorks™
Version 3.0 modeling software or calculated separately for input and output flows not captured
by the software. Background LCI information is comprised of extractive and manufacturing
processes that create material and energy inputs required by the wastewater treatment systems.
Background data are drawn from a version of the U.S. LCI as well as ecoinvent databases that
have been harmonized and modified by EPA's Office of Research and Development (ORD)
(LCA Research Center, 2015). Details on the data sources for the background databases used is
provided in Section 4.2 and detailed data sources and input and output flow values for the
foreground unit processes are provided in Section 4.3.
KP-C-16-003; WA 2^37
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Section 4: LCA Methodology
Raw Wastewaterand
Intermediate Inputs
Treated Wastewater
Coal Extraction
Inputs
Raw Coal {kg)
Grid Electricity {kWh)
Diesel {L)
Outputs:
Processed coal {kg)
PM2.5to air {kg)
Background System
1 I
Coal Power
Inputs
Processed Coal {kg)
Transport {tkm)
Grid Electricity {kWh)
Outputs:
Coal electricity {kWh)
C02to air {kg)
*
SOx to air {kg)
Electricity Mix
Inputs
Coal electricity {kWh)
Gas electricity {kWh)
Nuclear electricity {kWh)
Hydro electricity {kWh)
Line Losses {kWh)
Potable Water {m3)
Outputs:
Grid electricity {kWh)
C02to air {kg)
PM2.5to air {kg)
c
Primary Treatment
Inputs
Influent {m3)
Grid Electricity {kWh)
Outputs:
Primary effluent {m3)
Biological Treatment
Inputs
Primary effluent {m3)
Grid Electricity {kWh)
Cement {m3)
Steel {kg)
Earthwork {m3)
Outputs:
Secondary effluent {md]
CH4to air {kg)
N2Oto air {kg)
Post-Biological Treatment
Inputs
Secondary effluent {md]
Grid Electricity {kWh)
Outputs:
Effluent {m3)
Foreground System
Receiving Stream
Inputs
Treated H20 {m3)
Outputs:
N2Oto air {kg)
NH3 to water {kg)
Nature
KEY
Blue text
Intermediate inputs
— Background system
Each individual box represents an example unit process.
Green text
Emissions to environment
Foreground system
Inputs and outputs as well us unit processes listed are provided
Red text
Primary process output
Flow between unit processes
as an example, and are not considered exhaustive.
Raw inputs from nature
^ Flow to or from nature
Figure 4-1. Subset of LCA Model Structure with Example Unit Process Inputs and Outputs
EP-C'-16-003: WA 2-37
4-2
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Section 4: LCA Methodology
4.2 LCI Background Data Sources
The supply chains of inputs to the wastewater treatment processes are represented where
possible using the EPA ORD LCA database (U.S. EPA, 2015f), which is a modified combination
of the National Renewable Energy Laboratory's U.S. Life Cycle Inventory database (U.S. LCI)
and ecoinvent Version 2.2 (NREL, 2015; Ecoinvent Centre, 2010b). The U.S. LCI is a publicly
available life cycle inventory database widely used by LCA practitioners. Ecoinvent is also a
widely used global LCI database available by paid subscription. Both allow the user access to
inputs to and outputs from each unit process. Ecoinvent Version 3.2 is used to fill any gaps
where data do not exist in the EPA ORD LCA database, U.S. LCI or ecoinvent Version 2.2
(Ecoinvent Centre, 2015). The list of background unit processes and their associated database
source used in the LCA model is presented in Table 4-1.
Table 4-1. Background Unit Process Data Sources
li;ickumiiii(l Input
Oi'i'^iiiiil I nil Process Niimo
1.(1 Diiliihiisi*
Electricity
Electricity, at industrial user
EPA ORD LCA Database
Natural Gas
Natural gas, combusted in industrial
equipment
U.S. LCI
Chlorine Gas
chlorine, gaseous, diaphragm cell, at
plant
ecoinvent v2.2
Polymer
polyacrylamide
ecoinvent v3.2
Sodium Bisulfite (40%)
Sodium hydrogen Sulfite, 40% in
solution
ecoinvent v3.2
Sodium Bisulfite (12.5%)
Sodium hydrogen Sulfite, 12.5% in
solution
ecoinvent v3.2
Truck Transport
Truck transport, class 8, heavy
heavy-duty (HHD), diesel, short-
haul, load factor 0.5
ecoinvent v2.2
A1 Sulfate
Aluminium sulphate, powder, at
plant
ecoinvent v2.2
Calcium Carbonate
Lime, from carbonation, at regional
storehouse
ecoinvent v2.2
Methanol
Methanol, at plant
ecoinvent v2.2
Antiscalant
Polycarboxylates, 40% active
substance polycarboxylates
production, 40% active substance
ecoinvent v3.2
Citric Acid
Citric acid citric acid production
ecoinvent v3.2
Sodium Hypochlorite
Sodium hypochlorite, 15% in H20,
at plant
ecoinvent v2.2
Sulfuric Acid
Sulphuric acid, liquid, at plant_50%
in solution
ecoinvent v2.2
Sodium Hydroxide
Sodium hydroxide, 50% in H20,
production mix, at plant
ecoinvent v2.2
Earthwork
Excavation, hydraulic digger
ecoinvent v2.2
Concrete
Ready mixed concrete, 20 MPa, at
plant
EPA ORD LCA Database
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4-3
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Table 4-1. Background Unit Process Data Sources
li;ickumiiii(l Input
Oi'i'^iiiiil I nil Process Niimo
1.(1 Diiliihiisi*
Building
Building, hall, steel construction
ecoinventv2.2
Steel
Steel, low-alloyed, at plant
ecoinventv2.2
Gravel
Gravel, crushed, at mine
ecoinventv2.2
Anthracite
Anthracite, sand filter media
ecoinventv2.2
Sand
Silica sand, at plant
ecoinventv2.2
Electricity is a key background unit process for all the wastewater treatment
configurations investigated. Table 4-2 displays the U.S. average electrical grid mix applied in the
LCA model. This grid mix represents the weighted average of all U.S. grid regions, and as such
is not representative of the grid mix in any specific location. For electricity at an industrial user,
there is assumed to be a 21% increase in required electrical production attributable to losses
during distribution and the energy industries own use. These data are based on the Emissions &
Generation Resource Integrated Database (eGRID) information from 2009, which is currently
applied in the EPA ORD LCA Database (LCA Research Center, 2015).
Table 4-2. U.S. Average Electrical Grid Mix
1 ucl
°/o
Coal
44.8%
Natural Gas
24.0%
Nuclear
19.6%
Hydro
6.18%
Wind
2.29%
Woody Biomass
1.36%
Oil
1.02%
Geothermal
0.37%
Other Fossil
0.35%
Solar
0.03%
4.3 LCI Foreground Data Sources
As discussed earlier, for this study, the foreground system is defined as the WWTP itself.
For each of the nine wastewater treatment configurations evaluated, foreground information was
drawn directly from the CAPDETWorks™ Version 3.0 modeling software or calculated
separately for input and output flows not captured by the software. This section describes the unit
process LCI calculations, the methods used to estimate wastewater treatment process air
emissions, and a summary of the LCI foreground data used. The foreground LCI unit process
data developed for this study for all levels are summarized in Appendix H in Table H-l through
Table H-10. Table H-l 1 displays the sludge quantity produced and sent to landfill for each of the
nine wastewater treatment configurations.
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4.3.1 Foreground Unit Processes Calculations
Table 4-3 provides an overview of the foreground unit processes that make up each of the
wastewater treatment configurations evaluated in this study. The quantity and quality of water
inputs to and outputs from each unit process are tracked throughout the wastewater treatment
configurations. Energy, chemical, and material inputs (e.g., background unit processes) to each
of the unit processes are tracked in terms of energy, mass, or volume units. Also, rough estimates
of the construction and maintenance requirements of the infrastructure for each unit process are
tracked based on greenfield installations of the wastewater treatment configurations. In the case
of infrastructure and capital equipment requirements, past analyses have shown the contribution
of infrastructure to the overall results to be relatively insignificant (Emmerson et al., 1995). In
general, these types of capital equipment are used to treat large volumes of wastewater over a
useful life of many years. Thus, energy and emissions associated with the production of these
facilities and equipment generally become negligible. Only major infrastructure elements such as
concrete, earthwork, and buildings were, therefore, included in the study. Buildings were
modeled using a general material inventory per square meter of floor area (Ecoinvent, 2010b).
Releases to air and water as well as waste outputs are also tracked for each unit process.
Releases to air and water are tracked together with information about the environmental
compartment to which they are released to allow for appropriate characterization of their
impacts. Waste streams are connected to supply chains associated with providing waste
management services such as landfilling.
Table 4-3. Foreground Unit Processes Included in Each Wastewater Treatment
Configuration
I nil Process
\\ iislowiiloi' 1 iviilnu'iil ( onl'iiiuriilion
l.e\el
1.
AS
l.e\el
2-1.
\2()
l.o\d
\S3
l.oel
3-1.
155
l.oel
3-2.
Ml (1
l.e\el
4-1.
Ii5/I)cnil
1 .e\ i-l
4-2.
MliK
l.oel
5-1.
1)5/KO
l.e\el
5-2.
MBK/KO
Preliminary Treatment -
Screening
V
V
V
V
V
V
V
V
V
Preliminary Treatment -
Grit Removal
V
V
V
V
V
V
V
V
V
Primary Clarification
V
V
V
V
V
V
V
V
V
Plug Flow Activated
Sludge
V
V
Biological Nutrient
Removal - 3-Stage
V
Fermenter
V
V
V
V
V
Biological Nutrient
Removal - 4-Stage
V
V
Biological Nutrient
Removal - 5-Stage
V
V
V
V
Chemical Phosphorus
Removal
V
V
V
V
V
V
V
KP-C-16-003; WA 2^37
4-5
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Table 4-3. Foreground Unit Processes Included in Each Wastewater Treatment
Configuration
I nil Process
\\ iislowiiloi' 1 iviilnu'iil ( onl'iiiuriilion
l.e\el
1.
AS
l.e\el
2-1.
\2()
l.o\d
\S3
l.oel
3-1.
155
l.oel
3-2.
Ml (1
l.e\el
4-1.
Ii5/I)cnil
1 .e\ i-l
4-2.
MliK
l.oel
5-1.
IJ5/UO
l.e\el
5-2.
MliK/KO
Nitrification - Suspended
Growth
V
Denitrification -
Suspended Growth
V
Secondary Clarifier
V
V
V
V
V
V
V
Membrane Filter11 b
V
V
Tertiary Clarification
vc
Denitrification - Attached
Growth
V
V
Filtration - Sand Filter
V
V
V
V
Chlorination
V
V
V
V
V
V
V
V
V
Dechlorination
V
V
V
V
V
V
V
V
V
Ultrafiltrationa
V
Reverse Osmosis" d
V
V
WWTP Effluent Discharge
V
V
V
V
V
V
V
V
V
Sludge - Gravity
Thickening
V
V
V
V
V
V
V
V
V
Sludge - Anaerobic
Digestion
V
V
V
V
V
V
V
V
V
Sludge - Centrifugation
V
V
V
V
V
V
V
V
V
Sludge - Haul and Landfill
V
V
V
V
V
V
V
V
V
Brine - Underground
Inject
V
V
•J Indicates unit process is relevant for select wastewater treatment configuration,
a - Periodic chemical cleaning is included for all membranes.
b - Membrane bioreactor wastewater treatment configurations use a membrane filter for the solid-liquid separation
process instead of a traditional secondary clarifier.
c - This configuration includes two instances of tertiary clarification,
d - Includes chlorination and dechlorination pretreatment.
Foreground information was drawn directly from the CAPDETWorks™ Version 3.0
modeling software or calculated separately for input and output flows not captured by the
software. Although CAPDETWorks™ is designed for cost estimation, the underlying models
include a number of parameters which can be accessed and used to describe the physical
processes involved at each stage in the wastewater treatment configurations, such as sludge
generation or treatment chemical usage. An example of converting CAPDETWorks™ output to
KP-C-16-003; WA 2^37
4-6
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LCI is provided in Appendix G. Where CAPDETWorks™ parameters are not available for
populating relevant items in the unit processes underlying the LCA model, values are estimated
based on the best available information identified through literature review. Values for GHG
emissions from the wastewater treatment processes are not provided by CAPDETWorks™ and,
therefore, are estimated independently (See Section 4.3.2 and Appendix F). Calculation of inputs
and outputs for unit processes not covered in CAPDETWorks™ are also described separately in
Appendix E: Sections E.2 through E.7)
4.3.2 Process Air Emissions Estimation Methodologies
For this study it is necessary to separately estimate process-based greenhouse gas (GHG)
emissions for the nine wastewater treatment configurations. Emissions are already captured in
the background existing unit processes for fuel production and combustion as well as material
and chemical production (e.g., unit processes listed in Table 4-1). Estimates of process-based air
emissions are made for methane (CFU) production from biological treatment, anaerobic
digestion, landfill disposal of biosolids, and biogas flaring at the anaerobic digester. Estimates of
nitrous oxide (N2O) emissions from biological treatment and receiving waters are also included
in the analysis (IPCC, 2006). Separate methodologies have been developed based on the
available literature for each of these sources of GHGs. Carbon dioxide (CO2) emissions from
wastewater treatment processes are not included in the calculation of GHG emissions from
wastewater treatment processes because they are of biogenic origin and are not included in
national total emissions in accordance with IPCC Guidelines for national inventories (IPCC,
2006). The methodology for calculating GHG emissions associated with wastewater treatment is
generally based on guidance provided in the IPCC Guidelines for national inventories; however,
more specific emission factors for both CH4 and N2O are used based on site-specific emissions
data from representative systems. A detailed discussion of the process GHG emission values
incorporated in the model is provided in Appendix F. Appendix F also provides the GHG
emissions methodology developed for biogas flaring at the anaerobic digester (Table F-3) as well
as the GHG emissions methodology associated with avoided electricity from landfill CH4
recovery (Table F-7).
4.4 LCI Limitations
Some of the main limitations that readers should understand when interpreting the LCI
data and findings are as follows:
• Support Personnel Requirements: Support personnel requirements are included in
the cost analysis but excluded from the LCA model. The energy and wastes
associated with research and development, sales, and administrative personnel or
related activities are not included, as energy requirements and related emissions are
assumed to be quite small for support personnel activities.
• Representativeness of Background Data: Background processes are representative
of either U.S. average data (in the case of data from U.S. EPA ORD or U.S. LCI) or
European or Global average (in the case of ecoinvent) data. In some cases, European
ecoinvent processes were used to represent U.S. inputs to the model (e.g., for
chemical inputs) due to lack of available representative U.S. processes for these
KP-C-16-003; WA 2^37
4-7
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inputs. The background data, however, met the criteria listed in the project QAPP for
completeness, representativeness, accuracy, and reliability.
• Process GHG Estimates: There is uncertainty in estimating CH4 and N2O process
emissions from biological treatment and in differentiating the various treatment levels
due to the limited measurement data associated with the different wastewater
treatment configurations evaluated. Based on current international guidance, many
governments ignore CH4 GHG emissions in their national inventories from
centralized aerated treatment plants because they are considered negligible when
compared to other sources. The source of emission can be highly variable from
facility to facility and is not associated with the type of treatment configuration.
Facility-level process GHGs are also highly dependent on the specific operational
characteristics of a system used at one plant versus another, including pH,
temperature, and level of aeration. Minimum thresholds for determining differences
in GHG results between the waste treatment configurations are discussed in Section
4.6.15.
• Full LCI Model Data Accuracy and Uncertainty: In a complex study with literally
thousands of numeric entries, the accuracy of the data and how it affects conclusions
is truly a difficult subject, and one that does not lend itself to standard error analysis
techniques. The reader should keep in mind the uncertainty associated with LCI
models (and the underlying CAPDETWorks™ model) when interpreting the results.
Comparative conclusions should not be drawn based on small differences in impact
results. For this study, minimum threshold guidelines to determine differences in
impact results are provided by category in Section 4.6.15.
• Temporal Considerations: The LCI model does not distinguish based on temporal
correlations and treat short-term and long-term impacts similarly, between emissions
or discharges that occur immediately and those that are long term. For instance, long-
term emissions of COD in landfill leachate from sludge disposal is incorporated in the
model. For the first 100 years, it is assumed the leachate is sent to a WWTP.
However, after 100 years it is assumed the landfill ceases to operate and there are still
some residual leachate emissions.
• Transferability of Results: The LCI data presented here relate to a theoretical
average U.S. WWTP with a greenfield installation and the conditions specified in
Section 1.2. LCI results may vary substantially for case-specific operating conditions
and facilities, and for retrofits of existing systems.
4.5 LCA Modeling Procedure
Development of an LCA requires significant input data, an LCA modeling platform, and
impact assessment methods. This section provides a brief summary of the LCA modeling
procedure. Each unit process in the life cycle inventory was constructed independently of all
other unit processes. This allows objective review of individual data sets before their
contribution to the overall life cycle results has been determined. Also, because these data are
reviewed individually, EPA reviewed assumptions based on their relevance to the process rather
than their effect on the overall outcome of the study. In most cases, individual unit processes
were parameterized to dynamically represent multiple treatment levels and configurations.
EP-C-I6-QQ3; WA 2^37
4-8
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The model was constructed in OpenLCA Version 1.4.2, an open-source LCA software
package provided by GreenDelta (GreenDelta, 2015). This open-source format allowed seamless
sharing of the LCA model between project team members. For all novel foreground unit
processes developed under this work, individual unit process templates were completed into the
United States Department of Agriculture (USDA) and U.S. EPA's US Federal LCA Commons
Life Cycle Inventory Unit Process Template (USDA and U.S. EPA, 2015). The OpenLCA model
was reviewed to ensure that all inputs and outputs, quantities, units, and metadata correctly
matched the unit process templates. Associated metadata for each unit process was recorded in
the unit process templates along with the model values. This metadata includes detailed data
quality indicators (DQI) for each flow within each unit process.
Once all necessary data were input into the OpenLCA software and reviewed, system
models were created for each treatment level configuration. The models were reviewed to ensure
that each elementary flow (e.g., environmental emissions, consumption of natural resources, and
energy demand) was characterized under each impact category for which a characterization
factor was available. The draft final system models were also reviewed prior to calculating
results to make certain all connections to upstream processes and weight factors were valid.
LCIA results were then calculated by generating a contribution analysis for the selected
treatment configuration product system based on the defined functional unit of treatment of one
cubic meter of wastewater. The subsequent section discusses the detailed LCIA methods used to
translate the LCI model in OpenLCA into the impact categories assessed in this study.
4.6 Life Cycle Impact Assessment (LCIA)
LCIA is defined in ISO 14044 section 3.4 as the "phase of life cycle assessment aimed at
understanding and evaluating the magnitude and significance of the potential environmental
impacts for a product system throughout the life cycle of the product (ISO, 2006b)." Within
LCIA, the multitude of environmental LCI flows throughout the entire study boundaries (e.g.,
raw material extraction through chemical and energy production and through wastewater
treatment and effluent release) are classified according to whether they contribute to each of the
selected impact categories. Following classification, all of the relevant pollutants are normalized
to a common reporting basis, using characterization factors that express the impact of each
substance relative to a reference substance. One well known example is the reporting of all GHG
emissions in C02-eq. The LCI and LCIA steps together compromise the main components of a
full LCA.
ISO 14040 recommends that an LCA be as comprehensive as possible so that "potential
trade-offs can be identified and assessed (ISO, 2006a)." Given this recommendation, this study
applies a wide selection of impact categories that encompass both environmental and human
health indicators. The selected LCIA categories address impacts at global, regional, and local
scales.
This study considers 12 impact categories in assessing the environmental burdens of the
nine wastewater treatment configurations. The majority of impact categories address air and
water environmental impacts, while three of the selected impact categories are human health
impact indicators. There are two main methods used to develop LCIA characterization factors:
midpoint and endpoint. The impact categories selected for this study are all midpoint indicators.
EP-C-I6-QQ3; WA 2^37
4-9
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Midpoint indicators are directly associated with a specific environmental or human health
pathway. Specifically, midpoint indicators lie at the point along the impact pathway where the
various environmental flows that contribute to these issues can be expressed in a common unit
(e.g., C02-eq). Units such as CO2 equivalents express a relevant environmental unit, in this case
radiative forcing (W-yr/m2/kg), in the context of a reference substance. This is mentioned to
reinforce the fact that there are physical mechanisms underlying all of the impact assessment
methods put forward. Endpoint indicators build off of these midpoint units and translate them
into impacts more closely related to the final damage caused by the substance, which include: (1)
human health, (2) man-made environment, (3) natural environment, and (4) natural resources
(Udo de Haes et al., 1999). It is commonly believed that endpoint indicators are easier for many
audiences to understand, but suffer due to the fact that they significantly increase the level of
uncertainty associated with the results because the translation to final damage are typically less
understood and lack data. To reduce uncertainty of the results, this work generally focuses on
indicators at the midpoint level.
The LCIA method provided by the Tool for the Reduction and Assessment of Chemical
and Environmental Impacts (TRACI), version 2.1, developed by the U.S. EPA specifically to
model environmental and human health impacts in the U.S., is the primary LCIA method applied
in this study (Bare, 2012). Additionally, the ReCiPe LCIA method is recommended to
characterize fossil fuel depletion and water use (Goedkoop et al., 2009). Energy is tracked based
on point of extraction using the cumulative energy demand method developed by ecoinvent
(Ecoinvent Centre, 2010a).
Summaries of each of the 12 impact categories evaluated as part of this study are
provided in the subsequent sections. Each summary includes a table of the main substances
considered in the impact category, associated substance characterization factor, and the
compartment (e.g., air, water, soil) the substance is released to or extracted from (in the case of
raw materials). These tables highlight key substances but should not be considered
comprehensive.
4.6.1 Eutrophication Potential
Eutrophication occurs when excess nutrients (e.g., nitrogen or phosphorus) are introduced
to surface and coastal water causing the rapid growth of aquatic plants. This growth (generally
referred to as an "algal bloom") reduces the amount of dissolved oxygen in the water, thus
decreasing oxygen available for other aquatic species. Eutrophication midpoint indicators,
applied in this study, can lead to a number of negative endpoint effects on human and ecosystem
health. Oxygen depletion or changing nutrient availability can affect species composition and
ecosystem function. Additionally, the proliferation of certain algal species can result in toxic
releases that directly impact human health (Henderson, 2015).
Table 4-4 provides a list of common substances that contribute to eutrophication along
with their associated characterization factors. As indicated in the table, air emissions can also
contribute to eutrophication through the atmospheric deposition of nitrogen compounds. The
TRACI 2.1 eutrophication method considers emissions to both fresh and coastal waters. TRACI
2.1 characterization factors for eutrophication are the product of a nutrient factor and a transport
factor (Bare et al., 2003). The nutrient factor is based on the amount of algae growth caused by
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4-10
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each pollutant. The relative eutrophying effect of a nitrogen or phosphorus species is determined
by its stoichiometric relationship to the Redfield ratio (Norris, 2003). The Redfield ratio is the
average C:N:P ratio of phytoplankton, and describes the necessary building blocks to facilitate
algal growth and reproduction (Redfield, 1934). The transport factor accounts for the likelihood
that the pollutant will reach a body of water based on the average hydrology considerations for
the U.S. The transport factor is used to account for the fact that a nutrient reaching a body of
water where it is not limiting will not contribute to eutrophication. Both air and water emissions
have the potential to contribute to eutrophication; however, the fraction of air emissions which
make their way into bodies of water is often lower, which is reflected in a smaller transport
factor, and the correspondingly lower characterization factors of nitrogen oxide air emissions in
Table 4-4.
Both BOD and COD are also shown in Table 4-4 as contributing to eutrophication
impacts. Although the mechanism of oxygen consumption differs from that associated with
nutrient emissions of nitrogen and phosphorus, the result remains the same. Only COD (and not
BOD) values are characterized in this study to avoid double-counting (Norris, 2003).
In this study, U.S. average characterization factors are used, which are created as a
composite of all water basins in the U.S. For a discussion of the procedure used to produce
composite U.S. characterization factors, see Norris (2003). Using these factors, the results
account for regional variation in nutrient and transport factors, although that regional variability
is not presented in a disaggregated form. This is appropriate for the scope of this study as our
aim is to estimate average U.S. impacts of wastewater treatment. However, it must be recognized
that context specific features of an individual WWTP could serve to ameliorate or increase site-
specific impacts. In addition, waterbody-specific nutrient limitations and local transport
characteristics tend to be the most decisive factors in determining regional differences in
eutrophication impacts (Henderson, 2015).
Table 4-4. Main Pollutants Contributing to Eutrophication Potential Impacts
(kg N eq/ kg Pollutant)
Polliiliini
( Ih-iiiic;il l-'oi'iniilii
C oni p;i ri moil I
( h;ii'iiclcri/iilion l ;ic(or
BOD5, Biological ()\\gen Demand
\ \
Water
0.05
COD, Chemical Oxygen Demand
N/A
Water
0.05
Ammonia
nh3
Water
0.78
Nitrate
no3-
Water
0.24
Nitrogen dioxide
no2
Air
0.04
Nitrogen monoxide
NO
Air
0.04
Nitrogen oxides
NOx
Air
0.04
Nitrogen, organic bound
N/A
Water
0.99
Phosphate
PO,3
Water
2.4
Phosphorus a
P
Water
7.3
Selected Method—
TRACI 2.1
a - Represents phosphorus content of unspecified phosphorus pollutants (e.g., "total phosphorus" in effluent
composition).
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4.6.2 Cumulative Energy Demand
The cumulative energy requirements for a system can be categorized by the fuels from
which energy is derived. This method is not an impact assessment, but rather is a cumulative
inventory of all energy extracted and utilized. Energy sources consist of non-renewable fuels
(natural gas, petroleum, nuclear and coal) and renewable fuels. Renewable fuels include
hydroelectric energy, wind energy, energy from biomass, and other non-fossil sources.
Cumulative energy demand (CED) includes both renewable and non-renewable sources as well
as the embodied energy in biomass and petroleum feedstocks. CED is measured in MJ/kg.
Energy is tracked based on the higher heating value (HHV) of the fuel at the point of extraction.
Table 4-5 includes a few examples of fuels that contribute to CED in this project and their
associated characterization factors.
Table 4-5. Main Energy Resources Contributing to Cumulative Energy Demand
l!nerii\ Resource
( 0111 p;i ri 1110111
I nils
( hiiriiclcri/iilion
l";iclor
Energy, gross calorific value, in biomass
Resource (biotic)
MJ/kg
1.0
Coal, hard, unspecified, in ground
Resource (in ground)
MJ/kg
19
Gas, natural, in ground
Resource (in ground)
MJ/kg
47
Oil, crude, in ground
Resource (in ground)
MJ/kg
46
Selected Method—
Ecoinvent
4.6.3 Global Warming Potential
Global warming refers to an increase in the earth's temperature in relation to long-
running averages. In accordance with IPCC recommendations, TRACI's GWP calculations are
based on a 100-year time frame and represent the heat-trapping capacity of the gases relative to
an equal weight of carbon dioxide. Relative heat-trapping capacity is a function of a molecule's
radiative forcing value as well as its atmospheric lifetime. Table 4-6 provides a list of the most
common GHGs along with their corresponding GWPs, or CO2 equivalency factors, used in
TRACI 2.1. Contributing elementary flows can be characterized using GWPs reported by the
IPCC in either 2007 (Fourth Assessment Report) or in 2013 (Fifth Assessment Report) (IPCC,
2007; IPCC, 2013). While the 2013 GWPs are the most up-to-date, the 2007 GWPs have been
officially adopted by the United Nations Framework Convention on Climate Change (UNFCCC)
for international greenhouse gas reporting standards and are used by EPA in their annual
greenhouse gas emissions report. The baseline results in this study apply the 2007 GWPs, but
results with the 2013 GWPs are provided in a sensitivity analysis in Chapter 9.
Table 4-6. Main GHG Emissions Contributing to Global Warming Potential Impacts
(kg CO2 eq/kg GHG)
c;ik;
( Ik-iii ic;il
l-'o nil 11 hi
( <1111 p;irtllieill
c;\\ p iipcc 2oiri
C;\\ P 1 IPC ( 2013)
Carbon dioxide
C02
Air
1.0
1.0
Nitrous oxide
N20
Air
3.OE+2
2.7E+2
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4-12
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Table 4-6. Main GHG Emissions Contributing to Global Warming Potential Impacts
(kg CO2 eq/kg GHG)
CMC
( Ik-iii ic;il
l-'o nil 11 hi
( ompiiri 1110111
(;\\PdP( ( 20IP)
C;\\ P (IPCC 2013)
Melliane
Lit,
Aii-
25
:s
Sulfur
hexafluoride
sf6
Air
2.3E+4
2.4E+4
Selected Method—
IPCC 2007 or 2013 100a
4.6.4 Acidification Potential
The deposition of acidifying substances such as those listed in Table 4-7 have an effect
on the pH of the terrestrial ecosystem. Each species within these ecosystems has a range of pH
tolerance, and the acidification of the environment can lead to shifting species composition over
time. Acidification can also cause damage to buildings and other human infrastructure (Bare,
2012). The variable buffering capacity of terrestrial environments yields a correspondingly
varied response per equivalent unit of acidification. Due to a lack of data, the variable sensitivity
of receiving regions is not captured in TRACI characterization factors (Norris, 2003). The
acidification method in TRACI utilizes the results of an atmospheric chemistry and transport
model, developed by the US National Acid Precipitation Assessment Program (NAPAP), to
estimate total North American terrestrial deposition of expected SO2 equivalents due to
atmospheric emissions of NOx and SO2 and other acidic substances such as HC1 and HF, as a
function of the emissions location (Bare et al., 2003). Emissions location is modeled in this study
as average U.S. using TRACI's composite annual North American emissions average of U.S.
states.
Table 4-7. Main Pollutants Contributing to Acidification Potential Impacts
(kg SO2 eq/kg Pollutant)
Polliiiiini
( lu'iniciil l-'oi'iniilii
( oiii|);iriim-nl
Chiiniclci'i/iilioii
l";ic(or
Sulfur dioxide
S02
Air
1.0
Ammonia
nh3
Air
1.9
Nitrogen dioxide
N02
Air
0.70
Nitrogen oxides
NOx
Air
0.70
Hydrogen chloride
HC1
Air
0.88
Hydrogen fluoride
HF
Air
1.6
Hydrogen sulfide
H2S
Air
1.9
Selected Method—
TRACI 2.1
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4-13
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4.6.5 Fossil Depletion
Fossil depletion is a measure of the study systems demand for non-renewable energy
resources. As non-renewable resources, the availability of fossil energy will not change (i.e., new
fossil energy will not be produced) on relevant human timescales. When these resources are
depleted and resource quality declines, the cost and environmental impact of accessing a given
quantity of energy increases. Fossil depletion is measured in kg oil equivalent based on each
fuel's heating value. Renewable energy systems and uranium are not included in the fossil
depletion metric but are assessed within the CED methodology previously discussed. Table 4-8
presents common fossil fuel flows and their associated characterization factors for this impact
category.
Table 4-8. Main Fossil Fuel Resource Contributing to Fossil Depletion (kg oil eq/kg Fossil
Fuel Resource)
l-'ossil l-'ucl Resource
C 0111 p;i rt 1110111
( hiii'iiclori/iilion l ;ic(or
Oil, crude, 42 MJ per kg
Resource (in ground)
1.0
Coal, 18 MJ per kg
Resource (in ground)
0.43
Coal, 29.3 MJ per kg
Resource (in ground)
0.70
Gas, natural, 30.3 MJ per kg
Resource (in ground)
0.72
Gas, natural, 35 MJ per m3
Resource (in ground)
0.83
Methane
Resource (in ground)
0.86
Selected Method—
ReCiPe
4.6.6 Smog Formation Potential
The smog formation impact category characterizes the potential of airborne emissions to
cause photochemical smog. The creation of photochemical smog occurs when sunlight reacts
with NOx and volatile organic compounds (VOCs), resulting in tropospheric (ground-level)
ozone (O3) and particulate matter. Potential endpoints of such smog creation include increased
human mortality, asthma, and deleterious effects on plant growth. Smog formation potential
impacts are measured in kg of O3 equivalents. Table 4-9 includes a list of smog forming
chemicals expected to be associated with this project along with their characterization factors.
Table 4-9. Main Pollutants Contributing to Smog Formation Impacts (kg O3 eq/kg
Pollutant)
Polliiliiiil
( lu'iniciil
I'ormuhi
C 0111 p;i rt 1110111
( hiii'iicU'ri/iilioii I'iicloi'
Sulfur monoxide
SO
Air
1.0
Carbon monoxide
CO
Air
0.06
Methane
ch4
Air
0.01
Nitrogen dioxide
no2
Air
17
Nitrogen oxides
NOx
Air
25
VOC, volatile organic compounds
N/A
Air
3.6
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4-14
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Table 4-9. Main Pollutants Contributing to Smog Formation Impacts (kg O3 eq/kg
Pollutant)
I'olliiiiini
( Ik-iii ic;il
l-'oriiiulii
< 0111 |>;i rl 1110111
( li;ir;iiii-ri/;ilion l-'iiclor
Seleuled Melllud—
TRAC12.1
4.6.7 Human Health—Particulate Matter Formation Potential
Particulate matter (PM) emissions have the potential to negatively impact human health.
Respiratory complications are particularly common among children, the elderly, and individuals
with asthma (U.S. EPA, 2008a). Respiratory impacts can result from a number of types of
emissions including PM10, PM2.5, and precursors to secondary particulates such as sulfur
dioxide and nitrogen oxides. Respiratory impacts are a function of the fate of responsible
pollutants as well as the exposure of human populations. Table 4-10 provides a list of common
pollutants contributing to impacts in this category along with their associated characterization
factors. Impacts are measured in relation to PM2.5 emissions.
Table 4-10. Main Pollutants Contributing to Human Health-Particulate Matter Formation
Potential
(kg PM2.5 eq/kg Pollutant)
I'olliiiiini
( Ik-iii ic;il
l-'oriiiulii
( (im|iiiiiiiK-nl
( hiiriiclori/iilion I'iiclor
Particulates, <2.5 |im
N/A
Air
1.0
Particulates, >2.5 |im. and <
10 nm
N/A
Air
0.23
Ammonia
nh3
Air
0.07
Nitrogen oxides
NOx
Air
7.2E-3
Sulfur oxides
sox
Air
0.06
Selected Method—
TRACI 2.1
4.6.8 Ozone Depletion Potential
Stratospheric ozone depletion is the reduction of the protective ozone within the
stratosphere caused by emissions of ozone-depleting substance (e.g., CFCs and halons). The
ozone depletion impact category characterizes the potential to destroy ozone based on a
chemical's reactivity and atmospheric lifetime. Potential impacts related to ozone depletion
includes skin cancer, cataracts, immune system suppression, crop damage, other plant and animal
effects. Ozone depletion potential is measured in kg CFC-11 equivalents. Table 4-11 lists
common ozone depleting chemicals and their associated characterization factors in TRACI 2.1.
Nitrous oxide is incorporated in the results based on the ReCiPe hierarchies midpoint method
(Goedkoop et al., 2009).
KP-C-16-003; WA 2^37
4-15
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Table 4-11. Main Pollutants Contributing to Ozone Depletion Potential Impacts
(kg CFC11 eq/kg Pollutant)
Polliilsinl
( hem ic;i 1
l-'o nil ii hi
C 0111 p;i ri 1110111
( hsirsKieri/silion l-'iiclur
Ethane, 1, l,2-trichloro-l,2,2-trifluoro-,
CFC-113
C2CI3F3
Air
1.0
Methane, bromochlorodifluoro-, Halon
1211
CBrClFz
Air
7.1
Methane, bromotrifluoro-, Halon 1301
CBrF3
Air
16
Methane, chlorodifluoro-, HCFC-22
CHCIF2
Air
0.05
Methane, trichlorofluoro-, CFC-11
CCI3F
Air
1.0
Nitrons oxide
N.n
Air
0 01
Selected Method—
TRACI 2.1, ReCiPe
4.6.9 Water Depletion
Water use results are displayed on a consumptive basis (i.e., depletion). When water is
withdrawn from one water source and returned to another watershed this is considered
consumption, as there is a net removal of water from the original water source. For instance, it is
assumed that deepwell injection of the brine fluid from RO is consumptive water use, since water
is being diverted from a watershed making it unavailable for subsequent environmental or human
uses. Consumption also includes water that is withdrawn and evaporated or incorporated into the
product. Cooling water that is closed-loop circulated, and does not evaporate, is not considered
consumptive use. Water consumption is only included as an inventory category in this study,
which is a simple summation of water inputs. The analysis does not attempt to assess water-
related damage factors. For instance, there is no differentiation between water consumption that
occurs in water-scarce or water-abundant regions of the world. Water consumption in this study
includes values for upstream fuel and electricity processes. In addition to water consumption
associated with thermal generation of electricity from fossil and nuclear fuels, the water
consumption for power generation includes evaporative losses due to establishment of dams for
hydropower. Table 4-12 shows some of the common flows associated with water use along with
their characterization factors. Section 4.6.15 also discusses some of the uncertainty associated
with calculating water depletion in LCA.
Table 4-12. Main Water Flows Contributing to Water Depletion
\\ silcr How
('ompsirlmenl
I nils
( listrsicleri/silion l-sielor
Wnlei; lake
Resource (in water)
m3 EhO/m3
1.0
Water, river
Resource (in water)
m3 EhO/m3
1.0
Water, unspecified natural origin
Resource (in water)
m3 EhO/m3
1.0
Water, well, in ground
Resource (in water)
m3 EhO/m3
1.0
Water, unspecified natural origin/kg
Resource (in water)
m3 H20/kg
1.0E-3
Selected Method—
ReCiPe
KP-C-16-003; WA 2^37
4-16
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4.6.10 Human Health—Cancer Potential
Carcinogenic human health results in this study are expressed on the basis of
Comparative Toxic Units (CTUh) based on the USEtox™ method (Huijbregts et al. 2010).
Characterization factors within the USEtox™ model are based on fate, exposure, and effect
factors. Each chemical included in the method travels multiple pathways through the
environment based on its physical and chemical characteristics. The potential for human
exposure (e.g., ingestion or inhalation) varies according to these pathways. The effect factor
characterizes the probable increase in cancer-related morbidity for the total human population
per unit mass of a chemical emitted (i.e., cases per kg) (Rosenbaum et al., 2008). The full
USEtox™ model contains over 3,000 chemicals of global relevance and is the product of an
international project to harmonize the approach to evaluation of toxicity effects. The USEtox™
model develops characterization factors at the continental and global scale. The exclusion of
more localized parameters is justified in that it was found during the harmonization process that
site-specific parameters have a far lower impact on results than do the substances themselves.
Global midpoint characterization factors are employed from the most recent version of
USEtox™ available in OpenLCA, version 2.02. An updated version of USEtox™, version 2.11,
was released in April 2019. Characterization factors for the heavy metals, toxic organics and
DBPs were updated in the OpenLCA USEtox™ LCIA method to match version 2.11. All other
characterization factors remain at the default value for OpenLCA's USEtox version 2
(recommended+interim) database. Not all heavy metals, toxic organics and DBPs have
established characterization factors in the USEtox™ method. Several additional sources were
used to identify appropriate characterization factors. When no appropriate characterization factor
was identified, the pollutant was assigned a characterization factor equal to the median
characterization factor for its trace pollutant group. Table B-5, Table C-8, and Table D-4 list
values and sources of characterization factors for all heavy metals, toxic organics, and DBPs. For
illustration purposes, Table 4-13 lists five of the primary chemicals contributing to cancer human
health impacts in the US and Canada (Ryberg, 2014) along with their associated characterization
factors.
The developers of the USEtox™ method are clear to point out that some of the
characterization factors associated with human health effects should be considered interim,
owing to uncertainty in their precise values ranging across one to three orders of magnitude.
Sources of uncertainty are often attributable to the use of one exposure route as a proxy for
another (route-to-route extrapolation). For a more detailed discussion of uncertainty present in
these models, see the USEtox™ User's Manual (Huijbregts et al., 2010). Appropriate
interpretation of results must consider the uncertainty associated with the use of interim
characterization factors.
Table 4-13. Main Pollutants Contributing to Human Health - Cancer Potential Impacts
(CTUh/kg Pollutant)
Polliiliinl
Choiniciil l-'orniulii
( <1111 p;iriiiic-iil
( hiiriiclcri/iilion l ;ic(or
Arsenic
As
Soil
1.8E-4J
Formaldehyde
ch2o
Air
2.5E-5
KP-C-16-003; WA 2^37
4-17
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Table 4-13. Main Pollutants Contributing to Human Health - Cancer Potential Impacts
(CTUh/kg Pollutant)
Polliiliini
( lu'iniciil l-'orniulii
( ompiiriiiKMil
( hiiriiclcri/iilioii I'iiclor
Chromium VI
Cr
Soil
5.0E-33
Chromium VI
Cr
Air, urban
3.8E-33
Chromium VI
Cr
Water
0.01a
Selected Method—
USEtox™ 2.11
a - Designates an interim characterization factor.
4.6.11 Human Health—Noncattcer Potential
Non-carcinogenic human health results in this study are expressed on the basis of
Comparative Toxic Units (CTUh) based on the USEtox™ method, which is incorporated in
TRACI 2.1. The impact method characterizes the probable increase in noncancer related
morbidity for the total human population per unit mass of a chemical emitted (i.e., cases per kg)
(Rosenbaum et al., 2008). These impacts are calculated using the same approach as that taken for
human health - cancer (Section 4.6.10).
Global midpoint characterization factors are employed from the most recent version of
USEtox™ available in OpenLCA, version 2.02. An updated version of USEtox™, version 2.11,
was released in April 2019. Characterization factors for the heavy metals, toxic organics and
DBPs were updated in the OpenLCA USEtox™ LCIA method to match version 2.11. All other
characterization factors remain at the default value for OpenLCA's USEtox version 2
(recommended+interim) database. Not all heavy metals, toxic organics and DBPs have
established characterization factors in the USEtox™ method. Several additional sources were
used to identify appropriate characterization factors. When no appropriate characterization factor
was identified, the pollutant was assigned a characterization factor equal to the median
characterization factor for its trace pollutant group. Table B-5, Table C-8, and Table D-4 list
values and sources of characterization factors for all heavy metals, toxic organics, and DBPs. For
illustration purposes, Table 4-14 lists the main chemicals contributing to noncancer, human
health impacts (Ryberg, 2014) along with their associated characterization factors.
As is discussed in Section 4.6.10, uncertainty in USEtox factors can range across one to
three orders of magnitude for interim characterization factors, which are identified in Table 4-14.
At the current time, all characterization factors for metal compounds are considered interim.
Appropriate interpretation of results must consider the uncertainty associated with the use of
interim characterization factors.
Table 4-14. Main Pollutants Contributing to Human Health—Noncancer Potential
Impacts (CTUh/kg Pollutant)
Pulliiliinl
('hoinic;il l-'oi'iniilii
( ompiirlmonl
( hiiriiclori/iilioii I'iicloi-
Acrolein
C3H4O
Soil
3.4E-5
Zinc, ion
Zn2+
Soil
1.4E-43
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4-18
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Table 4-14. Main Pollutants Contributing to Human Health—Noncancer Potential
Impacts (CTUh/kg Pollutant)
Polliiliini
( Ill-illic;il l-orniiil;i
( ompiirimoiil
( hiiriiclcri/iilion I'iiclor
Arsenic, ion
As3+
Soil
0.01a
Zinc, ion
Zn2+
Air, urban
5.7E-33
Mercury (+11)
Hg(H)
Air, urban
1.24a
Selected Method—
USEtox™ 2.11
a - Designates an interim characterization factor.
4.6.12 Ecotoxicity Potential
Ecotoxicity is a measure of the effect of toxic substances on ecosystems. The effects on
freshwater ecosystems are used as a proxy for general ecological impact. Characterization factors
within the ecotoxicity model are based on fate, exposure, and effect factors. Each chemical
included in the method travels multiple pathways through the environment. As a result of these
pathways, various compartments (e.g., freshwater, terrestrial) and the species they contain will
have differing opportunities to interact with the chemical in question (exposure). The effect
factor refers to the potential negative consequences on ecosystem health when exposure does
occur (Huijbregts, 2010). The exclusion of more localized parameters is justified in that it was
found during the harmonization process that these parameters have a far lower impact on results
than do the substances themselves. Ecotoxicity impacts are measured in terms of the Potentially
Affected Fraction of species due to a change in concentration of toxic chemicals (PAF m3
day/kg). These units are also known as comparative toxicity units (CTUe).
Global midpoint characterization factors are employed from the most recent version of
USEtox™ available in OpenLCA, version 2.02. An updated version of USEtox™, version 2.11,
was released in April 2019. Characterization factors for the heavy metals, toxic organics and
DBPs were updated in the OpenLCA USEtox™ LCIA method to match version 2.11. All other
characterization factors remain at the default value for OpenLCA's USEtox version 2
(recommended+interim) database. Not all heavy metals, toxic organics and DBPs have
established characterization factors in the USEtox™ method. Several additional sources were
used to identify appropriate characterization factors. When no appropriate characterization factor
was identified, the pollutant was assigned a characterization factor equal to the median
characterization factor for its trace pollutant group. Table B-5, Table C-8, and Table list values
and sources of characterization factors for all heavy metals, toxic organics, and DBPs. For
illustration purposes, Table 4-15 lists some of the main chemicals found to contribute to
ecotoxicity impacts (Ryberg, 2013) and their USEtox™ global characterization factors.
As is discussed in Section 4.6.10, uncertainty in USEtox factors can range across one to
three orders of magnitude for interim characterization factors, which are identified in Table 4-15.
At the current time, all characterization factors for metal compounds are considered interim.
Appropriate interpretation of results must consider the uncertainty associated with the use of
interim characterization factors.
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4-19
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Table 4-15. Main Pollutants Contributing to Ecotoxicity Potential Impacts
(CTUe [PAF m3.day/kg Pollutant])
I'olliiliinl
( Ik-iii ic;il
l-'o nil ii hi
(nni|);irliiK'iil
( h;ir;iiicri/;ilion l-;ic(nr
Zinc, ion
Zn2+
Ground water
1.3E+53
Chromium VI
Cr(VI)
Ground water
1.0E+53
Nickel, ion
Ni2+
Ground water
3.0E+53
Chromium VI
Cr(VI)
River
1.0E+53
Arsenic, ion
As3+
Ground water
1.5E+43
Selected Method—
USEtox™ within TRACI 2.11
a - Designates an interim characterization factor.
4.6.13 Normalization
Normalization is an optional step in LCIA that aids in understanding the significance of
the impact assessment results. Normalization is conducted by dividing the impact category
results by a normalized value. The normalized value is typically the environmental burdens of
the region of interest either on an absolute or per capita basis. The results presented in this study
are normalized to reflect person equivalents in the U.S. using TRACI v2.1 normalization factors
(Ryberg et al., 2013). Only impacts with TRACI normalization factors are shown. Some
categories like water use and CED are excluded due to lack of available normalization factors.
4.6.14 LCIA Limitations
While limitations of the LCI model are specifically discussed in Section 4.4, some of the
main limitations that readers should understand when interpreting the life cycle impact
assessment findings are as follows:
• Coverage of Emissions Leading to Toxicity: The scope for the results for the three
USEtox™ categories (human health—cancer, human health—noncancer, and
ecotoxicity) excludes toxicity from wastewater effluent and should be considered
with low confidence. These category results arc largely dependent on toxic pollutants
from sludge in a landfill. However, these toxic pollutants may also be present in the
effluent release at the WWTP. The toxicity impacts associated with the sludge and the
effluent are limited to pollutants selected in Chapter 2. Such toxic pollutants in the
effluent were not assessed in the baseline LCA model; therefore, the toxicity impact
categories are showing incomplete results.
• Transferability of Results: While this study is intended to inform decision-making
for a wide range of stakeholders, the impacts presented here relate to a theoretical
average U.S. WWTP. For instance, this study does not address geographic differences
that could impact WWTP design, cost options, or local variation in environmental
impacts. Further work is recommended to understand the variability of key
parameters across specific regional and facility-level situations. Also, the study
KP-C-16-003; WA 2^37
4-20
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looked at greenfield installations only so impacts or benefits would vary for
retrofitted operations.
• LCIA Method Uncertainty: In addition to the uncertainty of the LCI data, there is
uncertainty associated with the application of LCIA methodologies and normalization
factors to aggregated LCI. For example, two systems may release the same total
amount of the same substance, but one quantity may represent a single high-
concentration release to a stressed environment while the other quantity may
represent the aggregate of many small dilute releases to environments that are well
below threshold limits for the released substance. The actual impacts would likely be
very different for these two scenarios, but the LCI does not track the temporal and
spatial resolution or concentrations of releases in sufficient detail for the LCIA
methodology to model the aggregated emission quantities differently. Therefore, it is
not possible to state with complete certainty that differences in potential impacts for
two systems are significant differences. Although there is uncertainty associated with
LCIA methodologies, all LCIA methodologies are applied to different wastewater
treatment configurations uniformly. Therefore, comparative results can be determined
with a greater confidence than absolute results for one system. Minimum threshold
values for determining meaningful impact differences between wastewater treatment
configurations by category are provided in the next section.
4.6.15 Interpreting LCIA Results Differences
Interpretation of LCIA results requires interpretation of the uncertainty associated with
inventory data (lists of compounds and resources emitted or extracted by the system under study)
and the impact models used to characterize inventory data, translating emissions into impacts.
Note that there is also uncertainty associated with the definition of system boundaries, and
determination of cutoff values for exclusion of data.
The current state of practice in life cycle assessment includes a quantitative analysis of
the uncertainty in inventory data. In this study, much of the background process data, which is
part of the ecoinvent database, includes such uncertainty analyses. Possible underestimations of
uncertainty associated with ecoinvent are known (Weidema et al., 2011); however, ecoinvent and
agricultural inventory uncertainties are expected to be lower overall than impact uncertainty.
At the impact level, uncertainty is not yet typically included in LCA studies; indeed, not
all LCA software has this ability. A spatially explicit model of aquatic acidification (Roy et al.,
2014) analyzed both parameter uncertainty (via a Monte Carlo approach) and spatial uncertainty.
At the characterization factor level, parameter uncertainty contributed a factor of 100
uncertainty, whereas spatial variability ranged from 5 to 8 orders of magnitude for different
acidifying compounds.
At the analysis level, it is important to consider that uncertainty in inventory or
characterization is not purely multiplicative when considering differences between systems
(Hong et al., 2010). For many LCA analyses, many background and some foreground processes
will be shared between systems. For example, background electricity generation is often shared,
while chemical additives or concrete could be shared foreground processes for wastewater
treatment. Therefore, analyses of differences between systems must account for these shared
KP-C-16-003; WA 2^37
4-21
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processes. Within confidence bounds, systems may be different even if the difference between
their impact scores is less than the absolute uncertainty on the corresponding characterization
factor (e.g., factor 100 for acidification, from above).
In a case study, Humbert et al. (2009) provide guidelines for determining whether
differences in LCA impact results are meaningful. In the energy and global warming category,
this minimum significant difference is a 10 percent threshold (i.e., in comparing contributions to
this category, a difference lower than 10 percent is not considered to be significant). For
particulate matter formation, smog formation, acidification, ozone depletion, and eutrophication,
the minimum significant difference is 30 percent. For the toxicity categories, an order of
magnitude (factor 10) difference is typically required for a difference to be significant, especially
if the dominant emissions are different between scenarios or are dominated by long-term
emissions from landfills that can be highly uncertain. In the absence of a detailed uncertainty
analysis, these threshold guidelines may serve to help interpretation. This study uses the percent
difference thresholds defined by the Humbert et al. 2009 case study with the exception of GWP
impact results. As discussed in Section 4.4, there are case-specific uncertainties for estimating
GHG emissions from biological treatment. Therefore, this study uses a higher threshold of 30
percent to determine whether a notable GWP difference exists between wastewater treatment
configurations. There are also specific considerations for uncertainty thresholds for water
depletion results as discussed below.
There is currently a lack of water use data on a unit process level for LCIs. In addition,
water use data that are available from different sources do not use a consistent method of
distinguishing between consumptive use and non-consumptive use of water or clearly identifying
the water sources used (freshwater versus saltwater, groundwater versus surface water). A recent
article in the International Journal of Life Cycle Assessment summarized the status and
deficiencies of water use data for LCA, including the statement, "To date, data availability on
freshwater use proves to be a limiting factor for establishing meaningful water footprints of
products" (Koehler, 2008). The article goes on to define the need for a standardized reporting
format for water use, taking into account water type and quality as well as spatial and temporal
level of detail.
Water consumption is modeled using values reported in literature. In some cases,
consumptive use data may not be available. The ecoinvent database includes water in the life
cycle inventory as an input and does not record water released to the environment (i.e., as an
emission) or water consumed. However, ecoinvent is currently one of the most comprehensive
LCI sources on water for upstream processes; many other available databases do not report water
input/use as an inventory item. Therefore, when case-specific data were not available, ecoinvent
data were utilized for the water calculations. When utilizing ecoinvent, the data are adapted to
represent consumptive use to the extent possible: fresh water removed from the environment that
is not internally recirculated.
Because water consumption values are uncertain, a minimum 30 percent difference is
required to consider water consumption results significantly different. Comparative results can
be determined with a greater confidence than absolute results for one system.
EP-C-I6-QQ3; WA 2^37
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Section 5: Life Cycle Cost Baseline Results
5. Life Cycle Cost Baseline Results
This section presents the LCCA results for the nine wastewater treatment configurations
included in this study. Table 5-1 presents the total capital, total annual, and net present value for
each of the wastewater treatment configurations. As discussed in Section 3.3.2, the net present
value combines the one-time capital costs and periodic (annual) operating and maintenance costs
into one value for direct comparison of costs. The following sections provide additional
discussion differences with the results of the total capital and annual costs (Section 5.1) and net
present value (Section 5.2). The results are discussed by unit process and aggregated treatment
group, as shown in Table 5-2. For treatment groups, the unit processes are generally grouped
sequentially; however, preliminary treatment stages are grouped with disinfection, even though
these are not sequential unit processes because, in this study, these unit processes do not vary
between wastewater treatment configurations. Complete cost results are presented in Appendix
H.
Table 5-1. Total Costs by Wastewater Treatment Configuration
\\ ;is(c\\;ilcr 1 rciilmcnl
(onri^iiriilion
l oliil ( iipiliil (osl
(2014 S)
l oliil Amiiiiil ( osl''
(2014 S/\r)
\c( Prcscnl Value
(2014 S)
Level 1, AS
$55,300,000
$5,140,000
$204,000,000
Level 2-1, A20
$71,400,000
$5,470,000
$236,000,000
Level 2-2, AS3
$93,100,000
$10,150,000
$378,000,000
Level 3-1, B5
$86,400,000
$5,800,000
$267,000,000
Level 3-2, MUCT
$88,900,000
$5,960,000
$275,000,000
Level 4-1, B5/Denit
$92,800,000
$6,840,000
$301,000,000
Level 4-2, MBR
$90,100,000
$6,340,000
$285,000,000
Level 5-1, B5/RO
$160,000,000
$8,320,000
$439,000,000
Level 5-2, MBR/RO
$144,000,000
$8,070,000
$409,000,000
a - Total annual cost includes operational labor, maintenance labor, materials, chemicals, and energy (see Section
3.3 for details).
Table 5-2. Unit Processes by Treatment Group
Trc;ilmcnl (.roup
I nil Processes Included in (lie Slniic
Preliminary/Primary/Disinfection
Screening and Grit Removal
Chlorination
Primaiy Clarifier
Dechlorination
Biological Treatment
Activated Sludge
Tertiaiy Clarification, Nitrification
Secondary Clarifier
Denitrification, Suspended Growth
Anaerobic/Anoxic/Oxic (A20)
Nitrification, Suspended Growth
4-Stage Bardenpho
Membrane Filter
5-Stage Bardenpho
Fermentation
Tertiaiy Clarification, Denitrification
Modified University of Cape Town
Post-Biological Treatment
Sand Filtration
Ultrafiltration
Reverse Osmosis
Chemical Phosphorus Removal
Denitrification, Attached Growth
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5-1
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Section 5: Life Cycle Cost Baseline Results
Table 5-2. Unit Processes by Treatment Group
Trc;ilmcnl (.roup
I nil Processes Included in llic S(;i»c
Sludge Processing and Disposal
Centrifuge
Sludge Hauling and Landfill
Anaerobic Digester
Gravity Thickener
Effluent Release
Effluent Release
Brine Injection
Brine Injection
5.1 Total Capital and Total Annual Cost Results
As described in Section 3.3, the total plant costs are presented as the total capital costs
along with the total annual costs. This section presents the total capital and total annual costs and
describes the differences in cost by process contribution and treatment group.
5.1.1 Total Capital Costs
Total capital costs generally increase from Level 1 to Level 5, as presented in Figure 5-1.
For Level 2, the Level 2-1 A20 total capital costs are almost $22 million lower than the Level 2-
2 AS3 total capital costs. The total capital costs for Level 2-2 AS3 are also over $4 million
higher than both Level 3 wastewater treatment configurations. This is because the Level 2-2 AS3
wastewater treatment configuration includes three separate biological units (plug-flow activated
sludge, nitrification, and denitrification) with dedicated clarifiers, while the Level 2-1 A20,
Level 3-1 B5, and Level 3-2 MUCT wastewater treatment configurations only include one
biological unit that have three to five chambers with a secondary clarifier. The multiple clarifiers
in Level 2-2 AS3 also results in more sludge generation and, as a result, has larger sludge
processing and disposal units, which also contribute to the higher total capital cost for Level 2-2
AS3 compared to Level 2-1 A20 and both Level 3 wastewater treatment configurations. The
total capital cost for Level 2-2 AS3 is more comparable to both Level 4 wastewater treatment
configurations. Increasing effluent quality from Level 4 to Level 5 increases the total capital
costs by over $50 million because of the added post-biological treatment units (i.e.,
ultrafiltration, reverse osmosis, and deep injection well for Level 5-1 B5/RO and reverse osmosis
and deep injection well for Level 5-2 MBR/RO). Total capital costs for the
preliminary/primary/disinfection treatment group are included but are comparable for all of the
wastewater treatment configurations, as there are no significant design differences between these
portions of the wastewater treatment configurations.
For this study, the total capital costs for the biological treatment group generally
increases with increasing effluent quality because the biological treatment units are designed to
achieve increased nitrogen and phosphorus removals; increased nitrogen and phosphorus
removals require a larger sized and/or more complex biological treatment unit. Note that there
are biological treatment units outside of the study that may not follow this trend. However, the
Level 5-1 B5/RO biological treatment group total capital costs are similar to both Level 3 and
Level 4-1 B5/Denit biological treatment group costs because they have the same biological unit
processes (BNR plus secondary clarifier) and are designed to achieve the same nitrogen and
phosphorus removals. The Level 4-2 MBR and Level 5-2 B5/RO have higher biological
KP-C-16-003; WA 2^37
5-2
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Section 5: Life Cycle Cost Baseline Results
treatment group costs by more than $5 million. Although they are designed to achieve the same
nitrogen and phosphorus removals as Level 3, Level 4-1 B5/Denit, and Level 5-1 B5/RO, the
Level 4-2 MBR and Level 5-2 B5/RO have membrane bioreactors instead of secondary
clarifiers, which increases cost. For all these wastewater treatment configurations, the nitrogen
and phosphorus removed beyond the Level 3 targets is achieved through post-biological
treatment units (e.g., denitrification filter, ultrafiltration, reverse osmosis).
The post-biological treatment group is a component of all levels except Level 1 AS and
Level 2-1 A20 since these levels do not require chemical phosphorus removal or additional
nutrient control unit processes. The lowest post-biological treatment capital costs are for Level 2-
2 AS3 and Level 4-2 MBR, which only require chemical phosphorus removal. There is a large
jump in post-biological treatment capital costs for the Level 5 wastewater treatment system
configurations due to the addition of ultrafiltration and the reverse osmosis unit. The Level 5-1
B5/RO post-biological treatment capital cost is more than double the Level 5-2 MBR/RO
because Level 5-1 B5/RO also includes the sand filter, ultrafiltration, and has a larger reverse
osmosis unit.
The sludge processing and disposal treatment group capital costs are comparable for all
the wastewater treatment configuration except for Level 2-2 AS3, which has a larger anaerobic
digester, larger centrifuge, increased number of vehicles (hauling and land filling), and larger
onsite sludge storage shed (hauling and land filling) capital costs. As discussed previously, the
Level 2-2 AS3 system has three separate clarifiers and a very high alum dose that increases the
quantity of sludge generated even beyond that of higher performing wastewater treatment
configurations, which are able to achieve their level of phosphorus removal performance through
a combination of chemical precipitation and other unit processes.
The Level 5 wastewater treatment configurations both have RO which requires brine
disposal capital costs, while the other wastewater treatment configurations do not. The other
capital costs include the direct and indirect costs that are calculated as a percentage of the
purchased equipment cost component of the total capital cost (see Section 3.3.1 for details). As a
result, the other capital costs increase as the other components of the total capital costs increase.
KP-C-16-003; WA 2^37
5-3
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Section 5: Life Cycle Cost Baseline Results
$180M
$160M
^ $140M
o
(N
CO
O
U
+->
'Sh
u
+->
£
$160M
$120M
$100M
$80M
$60M
$40M
$20M
$0M
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS 3 B5 MUCL B5/Demt MBR B5/R0 MBR/RO
0 Preliminary/Primary/Disinfection
13 Post-Biological Lreatment
¦ Brine Injection
0 Biological Lreatment
~ Sludge Processing and Disposal
~ Other
Figure 5-1. Total Capital Costs by Aggregated Treatment Group
5.1.2 Total Annual Costs
Figure 5-2 presents the total annual costs for all the wastewater treatment configurations
broken into the annual cost components. The total annual costs are highest for Level 2-2 AS3,
followed by Level 5-1 B5/RO and Level 5-2 MBR/RO. The annual costs for operation labor is
highest for Level 2-2 AS3 because of the increased sludge processing and disposal from the 3-
sludge system. The maintenance labor for Level 1, Level 2-1 A20, and both Level 3 wastewater
treatment configurations is generally comparable, while the maintenance labor for Level 2-2
AS3, both Level 4, and both Level 5 wastewater treatment configurations is generally
comparable. The maintenance labor for Level 2-2 AS3, both Level 4, and both Level 5
wastewater treatment configurations is higher because these wastewater treatment configurations
have more unit processes. The materials annual costs are highest for Level 2-2 AS3, again due to
the increased sludge processing and disposal from the 3-sludge system. Level 2-2 AS3 annual
chemical costs are between 3.3 times (Level 5-1 B5/RO) and almost 8.5 times (Level 2-1 A20)
higher than the other wastewater treatment configurations due to the large alum dose for
chemical phosphorus removal in Level 2-2 AS3. This large dose is needed compared to other
wastewater treatment configurations because Level 2-2 AS3 achieves phosphorus removal solely
through chemical phosphorus precipitation while the other wastewater treatment configurations
have some level of biological phosphorus removal. The annual costs for Levels 5-1 B5/RO and
$144M
EP-C'-16-003: WA 2-37
5-4
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Section 5: Life Cycle Cost Baseline Results
5-2 MBR/RO are driven by the annual energy costs, which are between 2 times (Level 4-1
B5/MBR) and almost 4 times (Level 1 AS) higher than the annual energy costs for the other
wastewater treatment configurations because both Level 5 configurations include an energy-
intensive reverse osmosis unit.
$12M
$10.2M
!-h
C3
(L)
O
-------
Section 5: Life Cycle Cost Baseline Results
wastewater treatment configurations are high. These wastewater treatment configurations have
higher annual operational labor due to the membrane bioreactor and membrane cleaning
chemical costs. The Level 4-2 MBR also has supplemental methanol addition immediately
preceding the 4-stage Bardenpho reactor, which accounts for the higher chemical costs than
Levels 2-1 A20 and both Level 3 wastewater treatment configurations. The Level 4-1 B5/Denit
wastewater treatment configuration also has supplemental methanol addition to the
denitrification filter, but the methanol dose is lower than the Level 4-2 MBR.
The total annual costs for post-biological treatment are highest for Level 5-1 B5/RO,
followed by Levels 2-2 AS3, Level 4-1 B5/Denit, and Level 5-2 MBR/RO, which are all
comparable. The Level 5-1 B5/RO annual costs are the highest because of the high energy
demand for the ultrafiltration, reverse osmosis unit, and brine injection well, along with having
high material replacement costs for the ultrafiltration and reverse osmosis membranes. The Level
2-2 AS3 post-biological treatment annual costs are driven by the alum chemical costs for
chemical phosphorus removal. Level 4-1 B5/Denit post-biological treatment annual costs are
driven by operational and maintenance labor. The Level 5-1 MBR/RO post-biological treatment
annual costs are driven by energy demand for the reverse osmosis and brine injection well, along
with the materials replacement cost for the reverse osmosis membranes.
The sludge processing and disposal costs are comparable for all of the wastewater
treatment configurations, except for Level 2-2 AS3, which is about $1 million/year more than the
other configurations due to the additional sludge generated from the three clarifiers and high
alum dose for chemical phosphorus removal.
The Level 5 wastewater treatment configurations both have brine disposal, while the
other wastewater treatment configurations do not. The annual costs for the brine disposal are the
same for both Level 5 configurations.
KP-C-16-003; WA 2^37
5-6
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Section 5: Life Cycle Cost Baseline Results
$12M
Wh
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$10M
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-------
Section 5: Life Cycle Cost Baseline Results
$500M
$450M
$400M
$350M
o
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z
$100M
$50M
$0M
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Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS 3 B5 MUCL B5/Demt MBR B5/R0 MBR/RO
Figure 5-4. Net Present Value by Wastewater Treatment Configuration
5.3 Cost Results Quality Discussion
In accordance with the project's Quality Assurance Project Plan (QAPP) entitled Quality
Assurance Project Plan for Life Cycle and Cost Assessments of Nutrient Removal Technologies
in Wastewater Treatment Plants approved by EPA on March 25, 2015 (ERG, 2015c), ERG
subjected the LCCA results to a multi-stage review, verification, and validation process.
The LCCA methodology and results received three levels of technical review, including
conceptual review, developmental review, and final product review. ERG developed the planned
LCCA approaches and methods; subjected them to internal review by ERG technical reviewers
with knowledge relevant to engineering costing, but not directly involved in the approach
development; and discussed them with GLEC and EPA during regular project meetings. During
development of the LCCA methodologies and results, all CAPDETWorks™ output files and
supplemental cost estimation spreadsheets underwent internal technical review to verify the
estimates and calculations comported with the planned methods and approaches and confirm the
accuracy of the calculations. Finally, ERG conducted an overall assessment of the
reasonableness of the final LCCA results. For example, ERG confirmed that differences among
the unit-process and configuration-level costs, and other factors such as chemical demand,
EP-C'-16-003: WA 2-37
5-8
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Section 5: Life Cycle Cost Baseline Results
energy use, and sludge generation, were reasonable based on engineering judgement of the
relative size and complexity of the units and systems.
ERG validated the LCCA results by comparing them against available data that were not
used in the project to develop the LCCA. For the CAPDETWorks™ costing, ERG compared the
total capital and total annual costs and net present value costs for Level 1 AS, Level 2-1 A20,
Level 3-1 B5, Level 4-1 B5/Denit, and Level 5-1 B5/RO to similar treatment systems in Falk et
al., 2011, which are presented in Table 5-3. ERG was unable to identify additional literature that
included planning-level costs for greenfield wastewater treatment plants with similar wastewater
treatment configurations. The other wastewater treatment configurations were not included in
Falk et al., and are therefore not included in Table 5-3. In general, Falk et al. included limited
detail for a direct comparison with the wastewater treatment configurations included in this
study. As an example, Falk et al. did not provide the software used to develop the costs, only
included select design parameters for select unit processes, and did not present the unit process-
specific costs. The total capital costs in this study are 50-66% of the capital costs presented in
Falk et al. Falk (2017) noted that Falk et al. included a raw sewage pump station, more
conservative construction assumptions associated with site conditions (e.g., sheeting, shoring,
dewatering), and higher concrete unit costs than for this study. The total annual costs for this
study are between 1.5 and 5.0 times higher than the total annual costs in Falk et al. This
difference is predominately due to the scope of the annual costs; this study included operational
labor, maintenance labor, materials, chemicals, and energy, while Falk et al. only included
chemicals and energy. For this study, the operational labor, maintenance labor, and materials
accounted for 63 to 82% of the total annual costs. Although there are differences between the
costs developed for this study and presented in Falk et al., literature sources indicate that
CAPDETWorks™ construction estimates are within 20% of actual construction costs (U.S. EPA
OWM, 2008b). The net present value for this study are $66 million to $104 million higher than
the net present value from Falk et al. This is primarily due to the differences in total annual costs
discussed above, but also because Falk et al. used 5% discount rate and 3.5% escalation rate for
capital, energy, and non-energy components. This study calculated net present value using 3%
discount rate and did not escalate any costs.
Table 5-3. Total Costs Compared to Falk et al., 2011
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Level 2-1, A20
$71,400,000
$142,000,000
$5,470,000
$1,410,000
$236,000,000
$167,000,000
Level 3-1, B5
$93,100,000
$161,000,000
$10,150,000
$2,620,000
$378,000,000
$201,000,000
Level 4-1,
B5/Denit
$86,400,000
$171,000,000
$5,800,000
$3,570,000
$267,000,000
$234,000,000
Level 5-1,
B5/RO
$88,900,000
$243,000,000
$5,960,000
$5,570,000
$275,000,000
$335,000,000
a - ERG converted Falk et al.'s costs from 2010 dollars to 2014 dollars using the calculations presented in Section
3.2.1.
KP-C-16-003; WA 2^37
5-9
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Section 5: Life Cycle Cost Baseline Results
b - Total annual cost includes operational labor, maintenance labor, materials, chemicals, and energy (see Section
3.3 for details).
Validation of the cost results for ultrafiltration, reverse osmosis, and brine disposal was
difficult as these technologies represent the state-of-the-art in the municipal wastewater
treatment industry with few or no applications in the U.S. and little or no published data. For
ultrafiltration, ERG compared the cost results to Noble et al., 2003. Noble et al. describes a study
of the performance of a pilot-scale microfiltration treatment system, and provides detailed capital
and O&M cost estimates for a full-scale 5 MGD system. The vendor, US Filter, is a major
membrane technology provider. The study regards surface-water treatment, rather than domestic
wastewater treatment, and is somewhat dated. ERG found the capital costs for the two data
sources differed by approximately 11%, which is well within the range of uncertainty for
planning-level costs. ERG did not compare the operating and maintenance costs, as the Noble et
al., 2003 costs are specific to treatment of surface water and are not applicable to domestic
wastewater treatment.
For reverse osmosis, ERG compared the cost results to costs published by the Orange
County Water District, 2010. The Orange County report described the estimated capital costs for
a planned 30 MGD expansion of their Groundwater Replenishment System, which includes
treatment of domestic wastewater using reverse osmosis and other technologies. We found the
reverse osmosis capital costs for the two data sources differed by approximately 9%, which is
well within the range of uncertainty for planning-level costs.
Energy usage is a significant component of total operating and maintenance costs for
membrane technologies such as ultrafiltration and reverse osmosis. ERG validated the estimated
energy usage provided by vendors to a literature source WateReuse Research Foundation, 2014.
For ultrafiltration, estimated energy usage by the vendor (ERG, 2015a) and WateReuse Research
Foundation, 2014 were 0.5 kWh/kgal and 0.75 to 1.1 kWh/kgal, respectively. Due to concerns
regarding the validity of estimated energy usage, for the final ultrafiltration costs estimates, ERG
used the average estimated energy usage reported by these two sources (see Appendix E.5). For
reverse osmosis, estimated energy usage by the vendor (ERG, 2015b) and WateReuse Research
Foundation, 2014 were 1.2 to 2.4 kWh/kgal and 1.9 to 2.3 kWh/kgal, respectively. These two
estimates are similar and overlap for much of their range. For consistency with the ultrafiltration
cost methodology, for the final reverse osmosis cost estimates, ERG used the average estimated
energy usage reported by these two sources (see Appendix E.6).
ERG was unable to validate estimated brine disposal costs as published costs for deep
well disposal of domestic wastewater are not available.
KP-C-16-003; WA 2^37
5-10
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Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
6. Life Cycle Impact Assessment Baseline Results by Treatment Group
This section presents the LCA results for the nine wastewater treatment configurations by
impact category. Throughout this section, results calculated at the unit process level have been
aggregated by treatment group, as shown in Table 5-2. For the treatment groups, the unit
processes are generally grouped sequentially; however, preliminary treatment stages are grouped
with disinfection, even though these are not sequential unit processes because, in this study,
these unit processes do not vary by wastewater treatment configuration. In general, add-on
technologies that occur in the treatment train after the main biological treatment unit process are
classified as post-biological treatment, regardless of their treatment mechanism. The figures
presented in this section include the abbreviated wastewater treatment configuration names. The
associated full names with information on the differentiating unit processes were previously
provided in Table 1-2. Full LCIA results by unit process are provided separately in Appendix I.
For three high priority impact categories, eutrophication potential, CED, and GWP, results are
also presented according to the underlying processes that contribute to results regardless of their
treatment group. For example, all of the electricity use from each of the wastewater treatment
unit processes are combined to show the cumulative contribution of electricity use to each impact
category. It is important to note that uncertainties in life cycle data and LCIA are present in all
modeled treatment configurations. As discussed in Section 4.6.15, any difference lower than 10
percent is not considered significant for CED. Differences lower than 30 percent are not
considered significant for particulate matter formation, acidification, eutrophication, water
depletion, smog formation, fossil depletion, and ozone depletion. For the toxicity categories, an
order of magnitude (factor 10) difference is typically required to be meaningful. Because of this
uncertainty magnitude, the toxicity results are presented and discussed separately in Section 7.
Although there is uncertainty associated with LCIA methodologies, all LCIA methodologies are
applied to different treatment configurations uniformly. Therefore, comparative results can be
determined with a greater confidence than absolute results for one treatment configuration.
6.1 Eutrophication Potential
Given the focus of this project on wastewater treatment nutrient removal capacity,
eutrophication is a critical metric for measuring the environmental performance of the nine
studied treatment configurations. As discussed in Section 4.6.1, eutrophication occurs when
excess nutrients are introduced to surface and coastal water causing the rapid growth of aquatic
plants. Table 6-1 presents the nutrient concentrations and annual loads for the influent and
effluent from the nine wastewater treatment configurations. Although the modeled
concentrations and resulting loads are not identical between the two alternatives for some of the
levels, the treatment objectives are the same and would generally result in the same effluent
quality, with the possible exception of Level 2. The results associated with the Level 2 treatment
configuration is provided in the next paragraph.
For this study, ERG designed the wastewater treatment configuration models in
CAPDETWorks™ to achieve specific effluent nutrient concentrations. As such, there is a step-
wise decreasing trend in total nitrogen and total phosphorus effluent concentrations and loads
with increasing treatment levels. The only exception to this is the total phosphorus effluent
concentration for Level 2-1 A20, which is lower than the Level 2 total phosphorus effluent
target of 1 mg/L. This is due to the way CAPDETWorks™ calculates effluent total phosphorus
EP-C-I6-QQ3; WA 2^37
6-1
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
from secondary clarifiers. To achieve total suspended solids of 20 mg/L for Level 2-1 A20, the
total phosphorus effluent concentration is about 0.3 mg/L; revising the clarifier design
parameters to achieve total phosphorus effluent concentration of 1 mg/L results in total
suspended solids around 70 mg/L, which is over the secondary treatment standards.
Table 6-1. Nutrient Discharges by Wastewater Treatment Configuration
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8,570
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7.8
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6,770
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3,050
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3,020
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0.02
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58,800
0.02
549
Figure 6-1 presents eutrophication potential results grouped according to treatment group.
Eutrophication is the combined effect of direct nutrient discharges in the effluent, landfilled
sludge leachate, and the water discharges and air emissions from upstream inputs to the
treatment steps such as electricity and chemical production. The green bar represents the
eutrophi cation potential related to effluent release and is directly related to the designed
performance of each treatment level. As expected, the potential eutrophication impact from
effluent release for the conventional activated sludge configuration (Level 1) are significantly
greater compared to the other treatment configurations. The impact of effluent drops off
markedly for Level 2 treatment configurations and remain consistently lower throughout the
remaining treatment levels. Eutrophication impact potential is very similar for Levels 3 and 4;
although the effluent nitrate values for Level 4 are lower than Level 3, they are offset by an
increase in COD in the effluent (as shown in the effluent characteristics in Table 1-4).
The release of organic nitrogen, ammonia and phosphorus in the effluent drives the
observed potential eutrophication impact for the majority of wastewater treatment configurations
evaluated, whereas the contributions to eutrophication of the sludge and biological treatment
groups are relatively consistent across Levels 2 through 5. The eutrophication potential impact
from sludge disposal are primarily related to the long-term release of COD in landfill leachate
described previously in Section 4.4. Sludge processing and disposal eutrophication impact
generally does not vary substantially since the wastewater treatment configurations produce a
similar quantity of sludge sent to landfill, with the exception of Level 2-2. Level 2-2 has higher
eutrophication impact for the sludge processing and disposal treatment group because of the
higher sludge generation in this level from the significant use of chemical phosphorus
precipitation. The biological treatment step for conventional activated sludge has a noticeably
KP-C-16-003; WA 2^37
6-2
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Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
lower impact than the other levels, which is due to the lower energy intensity of the more basic
activated sludge treatment process. Overall, it is apparent that the potential cumulative
eutrophication impact generally decreases between Level 1 and Level 2 and then again between
Level 2 and Level 3 and Level 4. Level 5 results in an increase in eutrophication impact
compared to Level 4 due to the high energy intensity of RO and brine injection, which off-set the
reduction in impact associated with the effluent release. However, based on the uncertainty
thresholds for impact results, the eutrophication potential difference between Level 3, Level 4
and Level 5 wastewater treatment configurations is not considered significant. As discussed in
Section 4.6.1, both indirect and direct air and water emissions have the potential to contribute to
eutrophication. Eutrophication from these energy intensive unit processes is largely due to the
portion of the nitrogen oxide air emissions from upstream fuel combustion for electricity
production that is modeled as deposited in water bodies. Nitrogen oxide emissions are largely
associated with deposition from the combustion of coal in the average US electrical grid (coal is
currently estimated to contribute approximately 45 percent to the average U.S. electrical grid as
shown in Table 4-2, Section 4.2, which comes from 2009). For more detail, Table J-l in
Appendix J shows the contribution of each individual unit process to the overall eutrophication
potential for each wastewater treatment configuration. To compare electricity consumption
across the wastewater treatment configurations refer to Table H-l through Table H-10 in
Appendix H.
T3
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
Natural gas, infrastructure, chemicals, process emissions, and sludge transport cumulatively
contribute between 0.3 and 4 percent of eutrophication impact depending on treatment level.
T3
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
chemical production is visible in Figure 6-4, particularly for Level 2-2. Level 2-2 CED from
chemical production is largely associated with the methanol requirement for denitrification and
aluminum sulfate used for chemical phosphorus precipitation.
As discussed in Section 1.2.3, it may be possible, depending on the demand, to recycle
the effluent from Levels 1 through 5 for a variety of reuse applications ranging from landscape
irrigation to indirect potable reuse (U.S. EPA 2012b). While recycled water was not considered
in the system boundaries of this study, recycling the water would likely offset some of the
increased CED of the higher nutrient removal wastewater treatment configurations by displacing
production of potable water elsewhere. The magnitude of the offset would depend upon the
current source of water for that reuse application.
The effect of biogas energy recovery on CED is discussed in Section 9.5.
Level 1, Level 2-1, Level 2-2, Level 3-1
AS A20 AS3 B5
B Preliminary/Primary/Disinfection
~ Post-Biological Treatment
~ Effluent Release
• Total
Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
MUCT B5/Denit MBR B5/RO MBR/RO
~ Biological Treatment
~ Sludge Processing and Disposal
¦ Brine Injection
Figure 6-3. Cumulative Energy Demand Results by Treatment Group
EP-C'-16-003: WA 2-37
6-5
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Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
29
T3
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
processing and disposal GWP emissions. While indirect N2O emissions from wastewater after
discharge of effluent into receiving waters contribute less than three percent of GWP impact for
Levels 2 through 5, this source of GHG emissions constitutes nearly 13 percent of Level 1 GWP
These emissions decrease across the treatment levels corresponding to increased removal of
nitrogen from the final effluent. Nitrous oxide emissions from wastewater effluent are the result
of denitrification processes that occur in the receiving water after wastewater is discharged from
the treatment facility. Documentation of the N2O GHG calculations for receiving waters is
provided in Appendix F.
For more detail, please refer to Table J-3 and Table J-4, which shows the contribution of
individual unit processes to the overall GWP.
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCT B5/Denit MBR B5/RO MBR/RO
B Preliminary/Primary/Disinfection ~ Biological Treatment
~ Post-Biological Treatment ~ Sludge Processing and Disposal
~ Effluent Release ¦ Brine Injection
• Total
Figure 6-5. Global Warming Potential Results by Treatment Group
Figure 6-6 aggregates GWP impact according to process contribution, highlighting the
dominant contribution of electricity use to GWP impact. The relative percentage of GWP impact
provided by electricity use increases from a low of 28 percent for Level 1 to a high of 64 percent
for Level 5-2. Process GHG emissions from biological treatment units and anaerobic digestion
are the second largest source of GWP impact and are similar in magnitude to electricity
contributions for several treatment levels. The relative contribution of GHG process emissions is
greatest for Levels 3 and 4 due to the unit processes used to attain the high degree of nutrient
removal combined with a relatively lower energy footprint as compared to Level 5
configurations. For Level 1, the release of N2O emissions is shifted to receiving streams.
Natural gas use and landfill disposal of biosolids are both noticeable contributors to GWP
impact, remaining consistent across treatment configurations. Natural gas contributes between
four and 18 percent of GWP impact. Fugitive landfill methane emissions contribute a further
EP-C'-16-003: WA 2-37
6-7
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Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
three to 13 percent, depending upon the configuration. It is important to remember that fugitive
landfill emissions occur over long periods of time as the anaerobic degradation of sludge
proceeds in the landfill environment. Although the fugitive landfill methane releases occur
gradually over many years, the approach used here models the impacts of the aggregated
emissions using 100-year GWPs. This is consistent with the use of 100-year GWPs used for all
other life cycle GHG emissions, as discussed in Section 4.6.3. Future refinements to landfill
LCA modeling may include time-scale modeling of landfill methane emissions; however, this is
not part of the current study. Such future refinements of time scale modeling of long-term GHGs
may lead to exclusion of methane emissions released after 100 years. As discussed in Appendix
F Section F.1.5, this study has assumed landfill gas capture and energy recovery is based on
average municipal landfill statistics in the U.S. There are a few instances where relative impact
associated with these unit process categories can rise above ten percent for a specific treatment
level. Effluent release, landfill emissions, and natural gas use contribute 14, 13, and 18 percent of
Level 1 impact, respectively. Chemical use in Level 2-2, which relies heavily on chemical
phosphorus precipitation, contributes 11 percent of GWP impact.
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
acidification impact is associated with sulfur dioxide and nitrogen oxide emissions from coal
combustion. The contribution of biogas flaring to acidification impact, again from sulfur oxides
and nitrogen oxide emissions, varies between 0.1 and 9 percent depending on the treatment level
with lower levels having higher relative contributions from biogas flaring. The effect of biogas
energy recovery on acidification potential impact is discussed in Section 9.5. For more detail,
Table J-4. presents the contribution of individual unit processes to acidification potential impact.
0.10
0.09
s 0.08
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
figures prominently in the results, contributing approximately 13 percent of the impact
associated with Level 1. The absolute contribution of sludge hauling to fossil depletion is
greatest for Level 2-2 due to the increase in sludge volume associated with chemical
precipitation. The contribution of chemical use to fossil depletion amounts to over five percent of
impact for Level 1 and over nine percent for Level 4-1. The increase associated with Level 4-1 is
due to the use of methanol for denitrification. For more detail, Table J-5 shows the contribution
of individual unit processes to fossil depletion potential.
The high energy use in the biological treatment group is due to the biological treatment
units (e.g., 3-stage Bardenpho, Modified University of Cape Town) and membrane filtration
solids separation in Levels 4-2 and 5-2. For the biological treatment units, energy use is due to
aeration, mixing, internal recycle and return activated sludge pumping. Membrane filtration use
energy for aeration, permeate pumping, and internal recycle. Energy use for the post-biological
treatment group is high for Levels 4-1, 5-1, and 5-2. For Level 4-1, over 95 percent of post-
biological energy use is associated with the denitrification filter. For Level 5-1, post-biological
energy use is approximately 70 percent for the RO and 25 percent for ultrafiltration. For Level 5-
2, close to 100 percent post-biological energy use is for RO.
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCT B5/Denit MBR B5/RO MBR/RO
5 Preliminary /Primary /Disinfection ~ Biological Treatment
E3 Post-Biological Treatment ~ Sludge Processing and Disposal
~ Effluent Release ¦ Brine Injection
• Total
0.60
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
smog formation potential is due to coal combustion for the conventional activated sludge system
configuration. For Level 1, the relative smog formation impact of biogas flaring is 27 percent,
with the absolute impact of biogas flaring consistent across wastewater treatment configuration.
Other typical combustion processes such as transport and industrial manufacturing contribute
less than one percent of cumulative impact in this category. For more detail, Table J-6 shows the
contribution of individual unit processes to smog formation potential.
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCT B5/Denit MBR B5/RO MBR/RO
B Preliminary /Primary /Disinfection ~ Biological Treatment
~ Post-Biological Treatment ~ Sludge Processing and Disposal
~ Effluent Release B Brine Injection
• Total
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
1.2E-02
1.0E-02
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
-a 9.0E-6
-------
Section 6: Life Cycle Impact Assessment Baseline Results by Treatment Group
0.20
TJ 018
I 0.16
-------
Section 7: Toxicity LCIA Results
1. Toxicity LCIA Results
Toxicity results are presented for the three USEtox™ impact categories. Presented results
include impacts associated with metals, toxic organics and DBPs in effluent and sludge for each
wastewater treatment configuration as well as upstream impacts associated with energy,
chemical and material production.
Figure 7-1 presents summary contribution results for all nine treatments systems in the
three toxicity impact categories. The figure is intended to highlight the most important aspects of
each treatment configuration that contributes to toxicity impacts. All results in Figure 7-1 are
standardized such that the total impact of each treatment configuration equals 100%.
Contributions to impact are aggregated in the following groups: material and energy inputs,
effluent metals, effluent toxic organics, effluent DBPs, metals in sludge, and toxic organics in
sludge. Metals in liquid effluent are the dominant contributor among the three trace pollutant
categories. For treatment Levels 1 thorough 4-1, metals in liquid effluent are the single largest
contributor to ecotoxicity and non-cancer human health impacts. For Levels 4-2 through 5-2,
contributions from plant material and energy inputs dominate toxicity impacts. As treatment
becomes more rigorous from Level 1 to Level 5, the contributions of trace pollutants to toxicity
impact decrease. There is a slight increase in toxicity impacts associated with sludge landfilling
along the same continuum, however total toxicity contributions from sludge disposal never
exceed 10%. Contributions from toxic organic chemicals, either in sludge or liquid effluent, are
only visible for the non-cancer human health impact category amounting to four percent or less
of total impact for all treatment configurations. DBPs contribute greater than 10% of total impact
for the cancer human health impact category in Levels 1, 2-1, and 4-2.
It is important to consider the uncertainty inherent in the calculation of toxicity related
impacts using the USEtox™ method (Huijbregts et al., 2010). Many of the characterization
factors used to quantify impacts in these categories are considered interim by USEtox™
developers. All toxicity related characterization factors associated with metals and metal ions,
which dominate the results of this study, are considered interim at this time. Moreover, the
characterization factors assume impacts result from a specific ionic form of each metal species
that is not necessarily the same form in which the metal is emitted from treatment systems. This
is a common limitation of the USEtox™ method, and it implies the assumption that once
emitted, transformations to a more toxic form may occur within the receiving environment.
Overall, the uncertainty associated with interim characterization factors is between one and three
orders of magnitude (Huijbregts et al., 2010).
KP-C-16-003; WA 2^37
7-1
-------
Section 7: Toxicity LCIA Results
Figure 7-1. Contribution Analysis of Cumulative Toxicity Impacts
100%
90%
80%
s—»
O
| 70%
HH
•f' 60%
a
O 50%
+-»
•2 40%
£ 30%
o
U
20%
Ecotoxicity (CTUe/m3 wastewater
treated)
H Material and Energy Inputs
H Effluent, DBPs
Human Health - Cancer (CTUh/m3
wastewater treated)
~ Effluent, Toxic Metals
El Sludge, Toxic Metals
•V* ^ ^ y* bp' ^ ^
V Vv V3 V3 V V
Human Health - Non-Cancer
(CTUh/m3 wastewater treated)
~ Effluent, Toxic Organics
H Sludge, Toxic Organics
EP-C'-16-003: WA 2-37
7-2
-------
Section 7: Toxicity LCIA Results
7.1 Human Health-Cancer Potential
Figure 7-2 presents the human health-cancer results by treatment group. Error bars in the
figure represent the range of results generated by applying minimum and maximum removal
efficiency scenario assumptions outlined in Sections 2.1 and 2.2 for metals and toxic organic
pollutants, respectively. Contributions to toxicity impact from metals, toxic organics and DBPs
summarized in Figure 7-1 are included in this figure within the effluent release and sludge
processing and disposal treatment groups.
This figure reinforces the important contribution of metals in treatment plant effluent to
cumulative human health-cancer impacts for the lower treatment Levels. The figure also
demonstrates that for Level 5 treatment configurations, the increasing contribution of plant
material and energy inputs outweighs the benefits of effluent improvements. Electricity
consumption of the RO filter and brine injection system is primarily responsible for this increase.
The Level 2-2 treatment system is associated with the highest cancer potential impacts
attributable largely to aluminum sulphate production for chemical phosphorus precipitation.
When considering the average removal efficiency scenario, Levels 3-2 and 4-2 most
effectively balance improvements in effluent quality against the increase in material and energy
inputs required to achieve this goal. This is in large part due to the effectiveness of the MUCT
unit process (Level 3-2) and the MBR unit process (Level 4-2) in removing metals from the
liquid effluent. The MBR unit process, in particular, showed metal removal performance almost
on par with RO, though without the detrimentally high energy requirements.
The range of impacts found for Level 1 and 2-1 are also worth noting, as although
average metal removal efficiencies of these levels are lower than other configurations (around
40-60% depending on the metal), there is evidence to suggest that removals can be greater than
80% in some cases. Combined with lower process-based impacts, a high efficiency Level 1 or
Level 2-1 system may perform best with respect to human health-cancer potential impacts.
Table J-10 documents the contribution of individual unit processes to the human health -
cancer potential.
KP-C-16-003; WA 2^37
7-1
-------
Section 7: Toxicity LCIA Results
1.2E-8
« 1.0E-8
O
-
9.9E-09
•-
a>
"ea
£
11
-w
%
CS
!£
s
A
3
H
U
8.0E-9
6.4E-09
6.0E-9
4.3E-0"
4.0E-9
2.0E-9
5.7E-09
5.2E-09
4.5E-09
4.1E-09
3.7E-09
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCT B5/Denit MBR B5/R0 MBR/RO
~ Preliminary/Primary/Disinfection
~ Post-Biological Treatment
~ Effluent Release
• Total
~ Biological Treatment
~ Sludge Processing and Disposal
¦ Brine Injection
Figure 7-2. Human Health
Cancer Potential Results by Treatment Group (CTUh/m3
wastewater treated)
EP-C'-16-003: WA 2-37
7-2
-------
Section 7: Toxicity LCIA Results
7.2 Human Health-Noncancer Potential
Figure 7-3 presents the human health-noncancer results by treatment group. Error bars in
the figure represent the range of results generated by applying minimum and maximum removal
efficiency scenario assumptions outlined in Sections 2.1 and 2.2 for metals and toxic organic
pollutants, respectively. Contributions to toxicity impact from metals, toxic organics and DBPs
summarized in Figure 7-1 are included in this figure within the effluent release and sludge
processing and disposal treatment groups.
The toxicity impact of metals in treatment plant effluent is even more pronounced for the
non-cancer human health impact category where it dominates contributions for Level 1 through
Level 4-1 treatment configurations. Figure 7-1 shows that DBPs also contribute to non-cancer
human health potential especially for Levels 1 and 2-1. When considering the average removal
efficiency scenario, total toxicity impacts generally decrease as you move from lower treatment
levels to the Level 4-2 treatment system before again increasing for Level 5. The low impacts
associated with Level 4-2 are again associated with the high metals removal performance of the
MBR unit process without the high energy inputs required of the RO membrane separation
process. Also, the removal efficiency range is narrower for the membrane separation processes
than for the lower treatment levels that rely more heavily on less precise biological processes for
partitioning of metals to sludge. Even considering the high removal efficiency scenario for the
lower three treatment levels, total non-cancer potential impacts are greater than or equal to the
toxicity impact of Levels 4-2 and 5.
Table J-l 1 shows the contribution of individual unit processes to human health-
noncancer potential.
KP-C-16-003; WA 2^37
7-3
-------
Section 7: Toxicity LCIA Results
2.5E-7
3 2.0E-7
•-
a>
"ea
£
11
CS
!£
S
a
3
H
U
1.5E-7
1.4E-07
1.3E-0"
1.2E-07
1.0E-7
5.0E-8
1.0E-07
9.0E-08
1.1E-07
7.7E-08
5.°E-°8 j—]—
m
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCT B5/Denit MBR B5/R0 MBR/RO
B Preliminary/Primary/Disinfection
~ Post-Biological Treatment
~ Effluent Release
• Total
~ Biological Treatment
~ Sludge Processing and Disposal
¦ Brine Injection
Figure 7-3. Human Health - Noncancer Potential Results by Treatment Group (CTUh/m3
wastewater treated)
7.3 Ecotoxicitv Potential
Figure 7-4 presents ecotoxicity results by treatment group. Error bars in the figure
represent the range of results generated by applying minimum and maximum removal efficiency
scenario assumptions outlined in Sections 2.1 and 2.2 for metals and toxic organic pollutants,
respectively. Contributions to toxicity impact from metals, toxic organics and DBPs summarized
in Figure 7-1 are included in this figure within the effluent release and sludge processing and
disposal treatment groups.
Ecotoxicity impacts are also strongly linked to metals released with the liquid effluent,
especially for Levels 1 and 2. Similar to the previous toxicity impact categories, the average
removal efficiency results demonstrate a minimum toxicity impact associated with the Level 4-2
treatment system. However, taking into account the range of potential removal efficiencies, there
is considerable overlap in results between Level 4-2 and other configurations. For example, the
Level 5 treatment systems perform well compared to the lower treatment levels and provide
greater assurances of reaching the average removal efficiency performance due to the greater
EP-C'-16-003: WA 2-37
7-4
-------
Section 7: Toxicity LCIA Results
reliability of their membrane processes. However, when compared against high removal
efficiency scenarios for lower treatment levels, Level 5 systems may result in greater potential
impact. Likewise, considerable overlap in the estimated removal efficiency performance of
Levels 1 through 4-1 make it challenging to draw reliable conclusions regarding their relative
performance.
Table J-12 shows the contribution of individual unit processes to ecotoxicity potential.
600
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCT B5/Denit MBR B5/RO MBR/RO
~ Preliminary /Primary /Disinfection
~ Post-Biological Treatment
~ Effluent Release
• Total
~ Biological Treatment
~ Sludge Processing and Disposal
¦ Brine Injection
!£
S
jD 300
P
H
U
Figure 7-4. Ecotoxicity Potential Results by Treatment Group
(CTUe/m3 wastewater treated)
EP-C'-16-003: WA 2-37
7-5
-------
Section 8: Summary Baseline Results
8. Summary Baseline Results
This section presents the baseline summary LCIA and cost (as net present value) results
to understand the trade-offs in impacts between operation of the different wastewater treatment
configurations. Following a presentation of the baseline summary results, a normalization step is
applied to the LCIA results to interpret the relative magnitude of the different impact categories
assessed.
8.1 Baseline Results Summary
presents a summary of the relative results for the main impact categories. Results have
been normalized to the maximum impact within each category. The side-by-side presentation of
the results serves to highlight the trade-offs that exist between the various treatment
configurations for traditional LCIA categories. Summary results are also displayed in a table
format in Table 8-1. Figure 8-2 presents the results in Table 8-1 for three representative
treatment configurations in a graphical format to help visualize the relative impacts and trade-
offs. In this graph, seven of the LCIA endpoints and costs are displayed on their own axis in
spiral format, with the greatest impact furthest from the center. The shaded areas reflect a
"footprint" of impact. Graphical displays of the results in this manner can aid in interpreting
results and facilitating associated decision-making when comparing options. The specific
information presented in Figure 8-2 is intended to be purely illustrative and is not intended to
imply the relative importance of any endpoint or any winnowing of treatment configurations.
KP-C-16-003; WA 2^37
8-1
-------
Section 8: Summary Baseline Results
0%
Percent of Maximum
20% 40% 60% 80%
100%
Cost
Eutrophication Potential
Cumulative Energy Demand
Global Wanning Potential
Acidification Potential
Fossil Depletion
Smog Formation Potential
Particulate Matter Formation Potential
Ozone Depletion Potential
Water Depletion
Human Health Cancer
Human Health Non-Cancer
Ecotoxicity
~ Level 1, AS
~ Level 3-1, B5
E3 Level 4-2, MBR
~ Level 2-1, A20
~ Level 3-2, MUCT
~ Level 5-1, B5/RO
~ Level 2-2, AS3
¦ Level 4-1, B5/Denit
~ Level 5-2, MBR/RO
Figure 8-1. Relative LCIA and Cost Results for Nine Wastewater Treatment
Configurations
EP-C-16-003; WA 2-37
8-2
-------
Section 8: Summary Baseline Results
Table 8-1. Summary LCIA and Cost Results for Nine Wastewater Treatment
Configurations
(per m3 wastewater treated)
llll|)iicl
N;i mo
I nil
l.e\el 1.
AS
l.e\el
2-1.
\2()
1.e\el 2-
2, \S3
l.e\el 3-
1.
155
1 .o el
3-2.
Ml (1
1 .e\ el 4-
1.
IJ5/l)en
il
l .e\el 4-
2, MliK
1 .e\ el
5-1.
U5/UO
1 .e\ el 5-
2.
MliK/K
()
Cost
$ USD
0.64
0.7
4
1.2
0.84
0.86
0.94
0.89
1.4
1.3
Eutrophicati
on Potential
kg N eq
0.07
9.8
E-3
0.02
6.8E-
3
6.9E
-3
6. IE
-3
6.8E-
3
7.5
E-3
7.5E
-3
Cumulative
Energy
Demand
MJ
5.4
9.1
14
9.7
10
12
11
24
23
Global
Warming
Potential
kg C02
eq
0.52
0.7
7
0.92
1.0
0.96
1.1
1.1
1.8
1.8
Acidificatio
n Potential
kg S02
eq
0.01
0.0
3
0.03
0.03
0.04
0.04
0.04
0.0
9
0.09
Fossil
Depletion
kg oil
eq
0.12
0.2
0
0.30
0.22
0.23
0.28
0.25
0.5
4
0.51
Smog
Formation
Potential
kg 03
eq
0.13
0.2
6
0.29
0.28
0.30
0.34
0.33
0.7
5
0.72
Paniculate
Matter
Formation
PM2.5
eq
1.4E-3
3.3
E-3
3.5E
-3
3.6E-
3
3.9E
-3
4.5E
-3
4.4E-
3
0.0
1
0.01
Ozone
Depletion
Potential
kg
CFC-
11 eq
3.9E-6
3.8
E-6
2.0E
-6
7.6E-
6
3.7E
-6
7.4E
-6
7.3E-
6
7.7
E-6
7.7E
-6
Water
Depletion
m3
H20
8.0E-4
1.5
E-3
4. IE
-3
1.7E-
3
1.8E
-3
2.0E
-3
2.0E-
3
0.1
9
0.17
Human
Health
Cancer
Potential
CTUh
4.3E-9
5.1
E-9
9.9E
-9
4.5E-
9
4.IE
-9
5.2E
-9
3.7E-
9
6.4
E-9
5.7E
-9
Human
Health Non-
Cancer
Potential
CTUh
1.2E-7
1.3
E-7
1.4E
-7
1.0E-
7
9.0E
-8
1.1E
-7
5.0E-
8
7.7
E-8
6. IE
-8
Ecotoxicity
Potential
CTUe
338
385
409
269
283
292
208
317
286
KP-C-16-003; WA 2^37
8-3
-------
Section 8: Summary Baseline Results
Cost
($0 64-1 40)
Eutrophication
(0 0068-0 0700 kg I
Ecotoxicity
(269-338 CTUe)
Particulate Matter
(0 0014-0 0100 PM2 5 eq)
Health: Cancer
(4.3-6.4 e-09 CTUh)
Non-Cancer
0 e-08 CTUh)
Energy Demand
<5.4-24.0 MJ)
Health:
(77-12.
Water Depletion
(0 0008-0 1900 m3 H20)
Figure 8-2. Illustrative Comparison of LCI A and Cost Results for Three Wastewater
Treatment Configurations
EP-C-16-003: WA 2-37
8-4
-------
Section 8: Summary Baseline Results
8.2 Normalized Baseline Results
Normalization is a process of standardizing impact results in all categories such that the
contribution of impact results associated with the functional unit can be judged relative to total
national or global impact for a given category. Table 8-2 shows normalization factors and U.S.
national per capita impacts in the year 2008. This is the most recent year normalization factors
for LCA are available (Ryberg et al., 2014; Lippiatt et al., 2013). Normalization factors are not
available for the impact categories fossil depletion and CED; therefore, these categories are
excluded from the normalization step. Toxicity results are also excluded due to the higher
magnitude of uncertainty associated with normalization factors for these categories. The
normalization factor is the total U.S. impact for the specified category in 2008. Impact per person
is estimated by dividing the normalization factor by the U.S. population. The U.S. population in
2008 is estimated as 304,100,000 people (World Bank, 2016). So, for example, the second row
of Table 8-2 indicates that average per capita GHG emissions from all U.S. sources was just over
24 metric tons of CO2 eq in 2008.
Table 8-2. 2008 U.S. Normalization Factors and Per Capita Annual Impacts
lmp;icl ( ;ik'iior\ ''
I nil
Noriiiiili/iilion
l";iclor (I S-200X)
Impiicl per IVi s(i 11h
Source
Eutrophication
kg N eq/yr
6.6E+9
22
Ryberg et al., 2014
Global Warming
kg C02 eq/yr
7.4E+12
2.4E+4
Ryberg etal., 2014
Acidification
kg S02 eq/yr
2.8E+10
92
Ryberg etal., 2014
Smog
kg 03 eq/yr
4.2E+11
1.4E+3
Ryberg etal., 2014
Particulate Matter
Formation
kg PM2.5 eq/yr
7.4E+9
24
Ryberg etal., 2014
Ozone Depletion
kg CFC-11
eq/yr
4.9E+7
0.16
Ryberg etal., 2014
Water Depletion
liter H20 eq/yr
1.7E+14
5.6E+2
Lippiatt etal., 2013
a - Normalization factor not available for cumulative energy demand and fossil depletion, so these categories are
excluded from normalization step,
b - Impact per person calculated using 2008 population of 304,100,000.
The process of normalization allows us to better assess the significance of impacts by
providing absolute benchmarks at the national level. The functional unit for this study is a cubic
meter of wastewater treated. In order to provide a gross, general context to these numbers, this
presentation of normalized results calculates values based on the range of per capita municipal
wastewater that is generated each year. The average generation of domestic municipal
wastewater in the U.S. is estimated to be between 50 and 89 gallons per person per day
(Tchobanoglous et al., 2014). This is a large range, reflecting the wide variation in use patterns
as determined by factors such as climate, household size, and home and community conservation
measures. This level of daily use translates to an annual domestic wastewater generation between
70 and 123 cubic meters per year per person. By multiplying impact results calculated in this
study by the annual cubic meters of domestic wastewater treated each year at municipal
wastewater facilities and dividing by per capita normalization factors, it is possible to calculate
KP-C-16-003; WA 2^37
8-5
-------
Section 8: Summary Baseline Results
the approximate annual contribution of domestic wastewater treatment to total per capita impact
in each of the included impact categories. This calculation excludes wastewater generated by
commercial, public, and industrial sources, and therefore overestimates the impact from
individuals and does not reflect the full national burden of wastewater treatment. The results of
this calculation for the nine treatment systems and environmental impact in seven categories are
presented in Table 8-3.
The overall trend in results is the same as that for unnormalized results, with impact in
most categories increasing with the level of treatment. However, we can now more easily see the
dramatic reduction in normalized contribution to eutrophication between conventional activated
sludge treatment and all of the advanced treatment options. Overall per capita eutrophication
impact may decrease 12 to 36 percent when shifting from the Level 1 wastewater treatment
configuration to the higher nutrient removal wastewater configurations. The results highlight the
fact that emissions resulting from wastewater treatment do not contribute equally to all impact
categories. Wastewater treatment contributions to GWP and ozone depletion are less than one
percent of the average national per capita emissions that contribute to these impact categories
across all treatment levels. This implies that more emphasis should be put on eutrophication
results compared to GWP or ozone depletion results for the wastewater treatment sector.
Emissions associated with impact categories linked strongly with energy consumption such as
acidification, smog formation, particulate matter formation, and human health-cancer start out at
levels between zero and four percent per capita impacts, but rise to between three and 19 percent
per capita impacts by the time Level 5 treatment is reached. These results also demonstrate the
significance of impacts associated with a broad range of impact categories not typically thought
of in relation to wastewater treatment, particularly at the more advanced levels of nutrient
removal, and indicate a possibility for shifting burdens from eutrophication to other categories of
environmental impact.
KP-C-16-003; WA 2^37
8-6
-------
Section 8: Summary Baseline Results
Table 8-3. Estimated Annual Contribution of Municipal Wastewater Treatment Per Capita Impact in Seven Impact
Categories
lni|>;icl ( nk'iion ''
l.e\el 1. AS
l.e\el 2-1.
A2()
l.e\el 2-2.
AS3
l.i-u-1 3-1.
155
l.e\el 3-2.
Ml (1
l.e\el 4-1.
Ii5/I)enil
l.e\el 4-2.
MliK
1 .e\ el 5-1.
IJ5/UO
1 .e\ el 5-2.
MBK/KO
Eutrophication Potential
21 -38%
3 - 6%
5 - 9%
2 - 4%
2 - 4%
2 - 3%
2 - 4%
2 - 4%
2 - 4%
Global Warming
Potential
0.1-0.3%
0.2 - 0.4%
0.3 - 0.5%
0.3 - 0.5%
0.3 - 0.5%
0.3 - 0.6%
0.3 - 0.6%
0.5 - 0.9%
0.5 - 0.9%
Acidification Potential
1 - 2%
2 - 4%
2 - 4%
2 - 4%
3 - 5%
3 - 5%
3 - 5%
7 - 13%
7 - 12%
Smog Formation
Potential
1%
1 - 2%
1 - 3%
1 - 2%
2 - 3%
2 - 3%
2 - 3%
4 -1%
4 - 6%
Particulate Matter
Formation Potential
0 - 1%
1 - 2%
1 - 2%
1 - 2%
1 - 2%
1 - 2%
1 - 2%
3 - 5%
3 - 5%
Ozone Depletion
Potential
<1%
<1%
<1%
<1%
<1%
<1%
<1%
<1%
<1%
Water Depletion
<1%
<1%
<1%
<1%
<1%
<1%
<1%
2 - 4%
2 - 4%
a - Normalization factor not available for cumulative energy demand and fossil depletion, so these categories are excluded from normalization step,
b - Toxicity results are interim.
KP-C-16-003; WA 2^37
8-7
-------
Section 9: Sensitivity Analysis
9. Sensitivity Analysis
9.1 Overview
Sensitivity analysis is an important component in the production of robust LCA and
LCCA study results. As with any modeling process, the construction and analysis of an LCA and
LCCA model and results requires making and documenting many assumptions. Many individual
assumptions are known to have only an insignificant effect on the final impact results calculated
for a given functional unit, but the effect of other assumptions is uncertain or is known to be
significant. In the latter two cases, sensitivity analysis is employed to quantify the effect of
modeling choices on LCA results. In this study, a sensitivity analysis was performed on the
interest rate used in the LCCA analysis, the choice of GWP factors, the modeled electrical grid
fuel mix, and the treatment of anaerobic digestion biogas. A case study is also presented
illustrating cost results for a WWTP incorporating nutrient control technology as a retrofit rather
than as a greenfield plant. The details of what elements were changed in each of the models and
the subsequent effect on results categories are documented in the following subsections.
9.2 Interest and Discount Rates
As discussed in Section 3.3, ERG used the same value for the interest and discount rates.
While there are slight differences in the interest and discount rates, it is appropriate to use the
same value for the interest and discount rates when developing planning level costs. In this
sensitivity analysis, ERG changed the interest rate during construction (see Equation 12), which
is part of the total capital costs, and the real discount rate used to calculate the net present value
(see Equation 13) from 3% to 5%. The interest and discount rates are not used to calculate the
annual costs; as a result, this section focuses on changes to the total construction costs and net
present value. The 3% interest rate represents a conservative interest rate for a State Revolving
Fund (SRF) loan as the SRF average loan rate was 1.7% in April 2016 (U.S. EPA, 2016a). The
5% interest rate represents a worse-case scenario reflective of rates that WWTPs in poor
financial shape, but still able to borrow, would be able to obtain.
Figure 9-1 presents the total construction costs using the 3% and 5% interest and discount
rates. On average, the total construction costs increased by approximately 2.6% using the 5%
interest rate, due to an increase in the interest paid during construction. Figure 9-2 presents the
net present value using the 3% and 5% interest and discount rates. The net present value
decreased using the 5% interest and discount rates by an average of 18%. The difference in the
net present value is primarily because the majority of the costs for the wastewater treatment
configurations are annual costs that occur in the future, which become smaller when using the
5% discount rate versus the 3% discount rate.
EP-C-I6-QQ3; WA 2^37
9-1
-------
Section 9: Sensitivity Analysis
$180M
$160M
$140M
^ $120M
Ct$100M
+->
in
O
O $80M
+->
$60M
U
"3
o $40M
H
$20M
$0M
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCL B5/Demt MBR B5/R0 MBR/RO
S Lotal Construction - 3% ~ Lotal Construction - 5%
Figure 9-1. 3% versus 5% Interest Rate Total Construction Sensitivity Analysis Results
$164M
$160M
EP-C-16-003; WA 2-37
9-2
-------
Section 9: Sensitivity Analysis
$500M
$450M
$400M
^ $3 50M
xr?
tj-
0 $300M
CS
3 $250M
1
C $200M
CD
in
CD
£ $150M
(L)
£
$100M
$50M
$0M
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
AS A20 AS 3 B5 MUCL B5/Demt MBR B5/R0 MBR/RO
0 Net Present Value - 3% ~ Net Present Value - 5%
Figure 9-2. 3% versus 5% Interest and Discount Rate Net Present Value Sensitivity
Analysis Results
9.3 Global Warming Potential
In this sensitivity analysis, the effect of using IPCC's most recent 2013 GWPs from the
Fifth Assessment Report was assessed (IPCC, 2013). The baseline study used 2007 GWP factors
from the IPCC Fourth Assessment Report, which have been officially adopted by the UNFCCC
for international GHG reporting standards and are used by EPA in their annual greenhouse gas
emissions report (IPCC, 2007). GWPs are the values used to transform the emission of all
molecules that have heat trapping potential into a standardized unit. The standardization process
takes CO2 as its reference value setting its value to one, with all other factors being set relative to
that standard (i.e., kilograms CO2 eq.). There are many parameters that feed into determination
of CO2 eq. values, and the scientific basis for these values continues to evolve, with the IPCC
reviewing and updating factors as the evidence improves. Table 9-1 shows both the 2007 and the
updated 2013 IPCC GWP factors for the primary GHGs resulting from the life cycle of
wastewater treatment. The last column in the table show the percent change associated with the
2013 update relative to the 2007 values.
;340M
$301M
$247M
$194M
$165M
EP-C'-16-003: WA 2-37
9-3
-------
Section 9: Sensitivity Analysis
Table 9-1. 2007 versus 2013 IPCC GWPs
GHG
GWP
Percent Change
IPCC 2007
IPCC 2013
Carbon dioxide
1.0
1.0
0%
Nitrous oxide
3.0E+2
2.7E+2
-12%
Methane
25
28
+11%
The effect of the GWP update on cumulative results depends upon the relative
contribution of each GHG to the total GWP impact for each of the wastewater treatment
configurations. Across all nine wastewater treatment configurations, the effect of selecting the
2007 versus 2013 GWP factors was shown to alter the GWP impact scores by between 1.8 and
3.8 percent. Figure 9-3 shows the magnitude of these effects per cubic meter of treated
wastewater for each of the nine wastewater treatment configurations. The stacked bars
correspond to the three main GHGs, which are responsible for the majority of GWP impact. The
fact that methane and nitrous oxide are both prevalent GHGs for these systems, and the similarly
equal and opposite change in GWP results for these two gases served to mitigate the impact of
the update on cumulative results for this study. Table 9-2 lists the percent change in GWP impact
that results from the choice between 2007 and 2013 GWP factors. At an aggregate level, the
results of this study were not notably affected by GWP factor selection.
2.0
-------
Section 9: Sensitivity Analysis
Table 9-2. Percent Change in GWP Impact due to GWP Factor Selection
1 (Ml 1.
1 CM-I 2 1.
\2(>
1 i'\ i'l 2 2.
Wi
1 (Ml i 1.
It?
1 i 2.
Ml ( 1
1 .Ml 4 1.
U5 Dcnil
1 .M l 4 2.
MliU
1 i'\ i'l 5 1.
Ii5 U(>
1 i'\ i'l 5 2.
MliU K()
Percent Change®
2.5" o
2.7" o
3.7",,
2..1",,
2..V o
2.4" ii
1.8"„
1.8"„
a - Percent Change = (GWP2oi3-GWP2oo7)/GWP2oo7
9.4 Electrical Grid Mix
In this sensitivity analysis, an alternative electrical mix with a "cleaner" grid (e.g., shift
away from coal) was applied. Table 9-3 displays the electrical grid mix for the NorthEast Power
Coordinating Council (NPCC), in addition to the baseline average mix of fuels used as the basis
for this study. This information is based on eGRID data from 2012. NPCC covers states such as
New York, Connecticut, Rhode Island, Massachusetts, Vermont, New Hampshire, and Maine.
This electrical grid is included in a sensitivity analysis, as it contains a higher portion of
electricity from natural gas, nuclear, and hydro and a lower portion of electricity from coal as
compared to the U.S. average electrical grid. The last column of Table 9-3 presents the percent
change within individual fuel types when shifting from the baseline U.S. average electrical grid
mix to the NPCC electrical grid mix.
Table 9-3. NPCC eGRID Regional versus U.S. Average Electrical Grid Mix
IlK'l
liiisolinc I .S. A\er;iiie
Pcrccnl of Mix
NPCC Sensi(i\i(\ \n;il>sis
PciTcnl of Mix
Pcrcenl ( huntie
Coal
45%
3.1%
-93%
Natural Gas
24%
49%
+100%
Nuclear
20%
30%
+51%
Hydro
6.2%
12%
+94%
Wind
2.3%
1.6%
-28%
Biomass
1.4%
3.6%
+170%
Oil
1.0%
0.38%
-63%
Geothermal
0.37%
0%
-100%
Other Fossil
0.35%
1.1%
+220%
Solar
0.03%
0.03%
0%
When conducting the sensitivity analysis, the electrical grid mix that serves the
wastewater treatment plant is varied for each of the nine wastewater treatment configurations,
while the electrical grid mixes associated with background processes remain constant. This is
reasonable since it is likely background chemicals and fuels are not produced in the same region
of the U.S. that they are utilized. Results for all of the impact categories were rerun and
compared to the baseline values. As displayed in Figure 9-4, the relative impact of this
substitution depends both upon the wastewater treatment configuration and on the impact
category. The impacts in this figure are sorted, with the greatest average reduction across all
treatment levels shown at the top and the smallest average reduction across all treatment levels
shown at the bottom. The effect of this substitution of electrical grid mix on cumulative impact
scores is significant across the majority of impact categories and treatment levels with a few
KP-C-16-003; WA 2^37
9-5
-------
Section 9: Sensitivity Analysis
notable exceptions. Ozone depletion potential impact is not shown to be sensitive to the choice of
electrical grid with the percent change for all wastewater treatment configurations being less than
one percent. The impact on eutrophication potential for Levels 1 and 2 are overshadowed by the
predominance of eutrophying emissions associated with effluent release. Similarly, the effect on
water depletion impact for Level 5 is reduced due to the predominant impact of brine injection to
results in this category.
In general, those wastewater treatment configurations with a higher energy demand per
cubic meter of wastewater treated show a greater sensitivity to the source of electricity. A
number of interesting patterns are visible in Figure 9-4. The relative effect of this sensitivity
analysis between wastewater treatment configurations is most pronounced for eutrophi cation
potential. The percent change associated with eutrophi cation impacts in Level 1 and Level 5- are
approximately -1 and -50 percent, respectively. The large variation in these values can be
explained by large differences in the aspects of the LCA model that contribute to impact in each
category. As mentioned above, eutrophication impact for Level 1 is predominated by effluent
release, so the change in grid energy has little influence on impact. Alternatively, by the time
water is cleaned to Level 5 standards, there is so little nutrient content in the effluent itself that
electricity impact predominates. Similarly, for other impact categories that show an increasing
sensitivity to electricity choice as we move from Level 1 to Level 5, we can attribute this to the
increased contribution of electricity to impact results as effluent standards increase.
The consistently high effect on acidification and particulate matter impacts across the
treatment systems is demonstrative of the dependence of these impact categories on emissions
resulting from electricity production. Toxicity results are excluded from Figure 9-3.
The deviation in general trends associated with Level 2-2 are due to the exceptional
reliance of this wastewater treatment configuration on chemical flocculent for phosphorus
removal, and the impact associated with these chemical additions. In this way, this wastewater
treatment configuration is less sensitive to overall changes in the electrical grid fuel mix.
The findings of this sensitivity analysis indicate that electricity is a primary driver for
many of the impact categories assessed in this study. Utilization of "cleaner" fuels for electricity
or recovery of resources at the WWTP to produce energy on-site could serve to offset some of
the burdens realized when including additional energy intensive unit processes to achieve
increased nutrient removal.
KP-C-16-003; WA 2^37
9-6
-------
Section 9: Sensitivity Analysis
Percent Change3
-60% -50% -40% -30% -20% -10% 0%
Acidification Potential
Smog Formation Potential
Fossil Depletion
Particulate Matter Formation Potential
Water Depletion
Ozone Depletion Potential
S Level 1, AS
~ Level 3-1, B5
0 Level 4-2, MBR
~ Level 2-1, A20
~ Level 3-2, MUCT
~ Level 5-1, B5/RO
~ Level 2-2, AS3
¦ Level 4-1, B5/Denit
~ Level 5-2, MBR/RO
1 Percent Change = [(NPCCimpact-AvgGrid1mpact)/AvgGridimpact]
Figure 9-4. Electrical Grid Mix Sensitivity Analysis Results
EP-C'-16-003: WA 2-37
9-7
-------
Section 9: Sensitivity Analysis
Table 9-4. Electrical Grid Sensitivity Analysis, U.S. Average versus NPCC Electrical Grid (per m3 wastewater treated)
1 ill|>:icl Name
I nil
l.e\el 1. AS
l.e\el 2-1. A2()
l.e\el 2-2. A S3
l.e\el 3-1. IJ5
l.e\el 3-2.
Ml C I
l.e\el 4-1.
Ii5/I)ellil
l.e\el 4-2.
Mlik
1 .e\ el 5-1,
IJ5/KO
l.e\el 5-2,
Mlik/k()
I .S.
NPCC
I .S.
NPCC
I .S.
A\g.
NPCC
I .S.
NPCC
1 .S.
NPCC
I .S.
NPCC
I .S.
^g.
NPCC
I .S.
NPCC
I .S.
NPC
(
Global
Warming
Potential
kg C02
eq
0.52
0.44
0.77
0.58
0.92
0.72
1.0
0.83
0.96
0.73
1.1
0.88
1.1
0.86
1.8
1.2
1.8
1.2
Eutrophicati
on Potential
kg N eq
0.07
0.07
9.8E-3
8.6E-3
0.02
0.01
6.8E-3
5.4E-3
6.9E-3
5.5E-3
6.1E-3
4.5E-3
6.8E-3
5.1E-3
7.5E-3
3.6E-3
7.5E-3
3.7E-3
Acidification
Potential
kg S02
eq
0.01
6.9E-3
0.03
0.02
0.03
0.02
0.03
0.02
0.04
0.02
0.04
0.02
0.04
0.02
0.09
0.05
0.09
0.04
Fossil
Depletion
kg oil eq
0.12
0.10
0.20
0.15
0.30
0.24
0.22
0.16
0.23
0.16
0.28
0.20
0.25
0.18
0.54
0.36
0.51
0.34
Smog
Formation
Potential
kg 03 eq
0.13
0.10
0.26
0.18
0.29
0.21
0.28
0.20
0.30
0.21
0.34
0.24
0.33
0.23
0.75
0.51
0.72
0.49
Particulate
Matter
Formation
PM2.5 eq
1.4E-3
9.8E-4
3.3E-3
2.4E-3
3.5E-3
2.6E-3
3.6E-3
2.6E-3
3.9E-3
2.8E-3
4.5E-3
3.2E-3
4.4E-3
3.1E-3
0.01
7.4E-3
0.01
7.1E-3
Ozone
Depletion
Potential
kg CFC-
11 eq
3.9E-6
3.9E-6
3.8E-6
3.8E-6
2.0E-6
1.9E-6
7.6E-6
7.5E-6
3.7E-6
3.6E-6
7.4E-6
7.3E-6
7.3E-6
7.2E-6
7.7E-6
7.6E-6
7.7E-6
7.5E-6
Cumulative
Energy
Demand
MJ
5.4
4.5
9.1
6.8
14
11
9.7
7.3
10
7.7
12
9.3
11
8.3
24
17
23
16
Water
Depletion
m3 H20
8.0E-4
6.4E-4
1.5E-3
1.1E-3
4.1E-3
3.7E-3
1.7E-3
1.2E-3
1.8E-3
1.3E-3
2.0E-3
1.5E-3
2.0E-3
1.4E-3
0.19
0.18
0.17
0.17
KP-C-16-003; WA 2^37
9-8
-------
Section 9: Sensitivity Analysis
9.5 Biogas Energy Recovery
The baseline model assumes flaring of biogas produced during anaerobic digestion. This
sensitivity analysis investigates the effect on plant level environmental impact and life cycle cost
from shifting to energy recovery using a combined heat and power (CHP) engine.
9.5.1 System Description
Biogas system components include the prime mover, which drives the electrical
generator, a heat exchanger, gas processing/cleaning equipment, electrical controls and
enclosure. An Internal Combustion Engine (ICE) is modeled as the CHP prime mover. ICEs are
a common and industry tested technology (Wiser et al. 2010). Biogas exiting the anaerobic
digesters is at ambient pressure and is saturated with moisture. Compression, drying and removal
of impurities is required before gas can be combusted in a CHP engine. The biogas processing
and CHP system boundary is depicted in Figure 9-5. Biogas and CHP system specifications are
listed in Table 9-5.
Outside boundary: equipment material, cieaning chemicals
AD
Media disposal
t
Iron Sponge
Scrubber
Electricity
& media
Moisture
Removal
Compression
Media disposal
Siloxane
Removal
Electricity
input
Electricity
input
Media
input
Eneine emissions
t
Eneine
Electricity &
Thermal
output
Figure 9-5. System Diagram of Biogas Processing and CHP System
Iron sponge scrubbers are assumed for hydrogen sulfide (H2S) removal, being a widely
used and commercially proven technology. H2S is corrosive of metallic system components in
the presence of water, and can lead to elevated sulfur oxide (SOx) emissions from the prime
mover. H2S is a common constituent of biogas generated at municipal WWTPs often comprising
200-3500 ppmv of biogas (Wiser et al. 2010). A representative H2S concentration of 500 ppmv is
used to estimate iron sponge requirements (Wiser et al. 2010). The desired temperature range for
adsorption via iron sponge is between 25 and 60 °C, which corresponds to the temperature of
biogas as it exits the anaerobic digesters. Hydrated iron oxide is usually sold embedded onto
wood chips. Iron sponge adsorption requires the presence of moisture in the biogas, so process
placement before moisture removal is common. Approximately 20 kg of H2S can be adsorbed
per 100 kg of sorbent material (Ong et al. 2017). The oxide impregnated wood chips can be
regenerated by flushing the bed with atmospheric oxygen, which releases H2S as elemental
sulfur. The regeneration process can be repeated approximately 1 -2 times before the adsorbent
media requires replacement (Abatzoglou and Boivin 2009). This analysis assumes 1 regeneration
cycle, achieving 85 percent of original sorbent capacity. The necessary equipment has a modest
footprint and is usually located outdoors to mitigate safety concerns.
EP-C-14-022 WA 1-11
9-9
-------
Section 9: Sensitivity Analysis
Table 9-5. Biogas Processing and CHP System Specifications for Nine Treatment System Configurations
S\s(cm Paramcler
l.e\el 1.
AS
1 .e\ el 2-1.
\2()
1 .e\ el 2-2.
\S3
1 .e\ el 3-1.
155
1 .e\ el 3-2.
Ml (1
1 .e\ el 4-1.
Ii5/I)cnil
1 .e\ el 4-2.
MliK
1 .e\ el 5-1.
IJ5/UO
l.e\el 5-2.
MliK/KO
Annual Biogas Production (m3)
1.6E+6
1.3E+6
1.8E+6
1.3E+6
1.3E+6
1.3E+6
1.3E+6
1.3E+6
1.2E+6
Biogas Production (scfm)
1.1E+2
88
1.2E+2
85
85
85
87
85
82
Available Biogas Energy (MJ)a
2.7E+7
2.4E+7
3.2E+7
2.3E+7
2.3E+7
2.3E+7
2.3E+7
2.3E+7
2.2E+7
ICE Availability
0.90
0.90
0.90
0.90
0.90
0.90
0.90
0.90
0.90
ICE Power (kw)
3.2E+2
2.8E+2
3.8E+2
2.7E+2
2.7E+2
2.7E+2
2.8E+2
2.7E+2
2.6E+2
Electricity Production (kWh/yr)
2.5E+6
2.2E+6
3.0E+6
2.2E+6
2.2E+6
2.2E+6
2.2E+6
2.2E+6
2.1E+6
Thermal Energy (MJ/yr)
1.2E+7
1.1E+7
1.4E+7
1.0E+7
1.0E+7
1.0E+7
1.0E+7
1.0E+7
9.9E+6
AD Heat Requirement (MJ/yr)b'c
1.7E+7
1.6E+7
2.4E+7
1.5E+7
1.5E+7
1.5E+7
1.5E+7
1.5E+7
1.4E+7
WWTP Electricity Requirement
(kWh/yr)
2.8E+6
6.7E+6
6.8E+6
8.1E+6
8.6E+6
9.8E+6
8.2E+6
2.2E+7
2.0E+7
Percent of AD Heat Demand
Satisfied (%)
70%
68%
59%
67%
67%
67%
70%
67%
71%
Percent of Facility Electricity
Demand Satisfied (%)
90%
33%
43%
30%
27%
24%
25%
10%
10%
H2S removed (kg/day)
1.9
1.6
2.2
1.6
1.6
1.6
1.6
1.6
1.5
Iron Oxide requirement (kg/yr)
1.8E+3
1.6E+3
2.2E+3
1.6E+3
1.6E+3
1.6E+3
1.6E+3
1.6E+3
1.5E+3
Siloxane removed (kg/day)
0.44
0.36
0.48
0.35
0.35
0.35
0.36
0.35
0.33
Activated Carbon requirement
(kg/yr)
1.6E+3
1.3E+3
1.8E+3
1.3E+3
1.3E+3
1.3E+3
1.3E+3
1.3E+3
1.2E+3
a Accounts for 5 percent fugitive biogas loss and 20 percent flaring rate.
b Expressed as CHP thermal energy, accounts for 90 percent efficiency of heat exchanger.
0 AD - anaerobic digester/digestion
liP-C-14-022 WA 141
9-10
-------
Moisture removal is the next step in biogas processing as it enhances performance of the
subsequent siloxane removal step (Wiser et al. 2010). Moisture removal via chilling and
condensation is proposed to ensure sufficiently dry biogas. Refrigeration energy demands
typically account for less than two percent of the energy content of the processed biogas. A
conservative value of two percent is used to estimate electricity demands of the refrigeration
process (Ong et al. 2017).
Compression of biogas is necessary prior to combustion in the prime mover. Fuel
pressurization to between 3 and 5 psi is sufficient for use in ICEs. Use of a blower is
recommended for moderate compression requirements up to 15 psig (Wiser et al. 2010).
Compression follows H2S and moisture removal to ensure longevity of compressor components.
Blowers have the benefit of being low cost, require no oil, lack VOC emissions and have
minimal maintenance requirements (Wiser et al. 2010). Energy requirements for compression are
estimated based on the use of heavy duty rotary blowers that operate at brake horsepowers of
between 2.4 and 3.3 depending upon the biogas flowrate in standard cubic feet per minute
(scfm), which ranges between 82 and 118 scfm depending upon the system configuration (see
Table 9-5).
The final biogas cleaning and processing step involves removal of siloxanes, which are
another common contaminant of biogas generated via anaerobic digestion of wastewater sludge.
Siloxanes can be removed using refrigeration or sorbents such as activated carbon, alumina,
synthetic resins, or liquid sorbents. Siloxane removal via activated carbon adsorption is modeled
given its prevalent use, low cost and maintenance requirements. Coal is modeled as the activated
carbon feedstock, based on LCI information presented in Bayer et al. (2005).
The ICE is sized based upon the available energy content of biogas produced by each
system assuming a 90 percent availability factor (i.e. 10 percent system downtime). The quantity
of biogas available for energy consumption equals total biogas production less fugitive emissions
(5 percent) and flared biogas (UNFCCC 2012). The analysis assumes that 20 percent of biogas is
flared due to system downtime, upsets and lack of available storage capacity required to handle
inconsistency in biogas production. ICE power requirements range from approximately 260 to
380 kW depending upon the system configuration, placing it in line with other WWTP CHP
installations based on installed kW/MGD (U.S. DOE 2016). Electrical and thermal efficiency
values of 34 percent and 45 percent are selected, respectively, representing the average of the
reported ICE efficiency range in Wiser et al. (2010). ICE emissions are representative of an ICE
engine utilizing selective catalytic reduction for NOx control, and an oxidation catalyst system
for carbon monoxide and VOC emission control.
9.5.2 Biogas Sensitivity LCIA Results
LCI A results by treatment group are presented for GWP in Figure 9-6. The addition of
energy recovery yields a decrease in GWP impact for all system configurations due to the
avoided environmental burdens of natural gas and grid electricity consumption associated with
the electrical and thermal products of the CHP system. The absolute decrease in GWP impact
varies between 0.21 and 0.31 kg C02-eq. per m3 wastewater treated according to the quantity of
biogas available for energy recovery. The relative effect on system level GWP impact is greatest
for treatment Level 1, and decreases as total GWP impact increases for the higher levels of
KP-C-16-003; WA 2^37
9-11
-------
nutrient removal. The addition of energy recovery reduces Level 1 GWP impact by
approximately 50 percent, while the reduction in GWP impact for Level 5 treatment
configurations is less than 15 percent of base GWP impact. Base and CHP sensitivity LCIA
results and corresponding percent reduction values are presented for all impact categories in
Table 9-6. Figure 9-6 shows that the benefits of energy recovery are sufficient to offset the GWP
impact of the sludge processing and disposal treatment group.
Level 1, Level 4-1,
AS B5/Denit
CHP Base CHP Base
-0.5
0 Preliminary /Primary /Disinfection 0 Biological Treatment 0 Post-Biological Treatment
O Sludge Processing and Disposal O Effluent Release ¦ Brine Injection
• Total
Figure 9-6. Global Warming Potential by Treatment Group for Base Results and the CHP
Energy Recovery Sensitivity
Figure 9-7 presents results by treatment group for the CED inventory indicator, and
demonstrates reductions in system level energy demand for all treatment configurations.
Absolute reduction in CED range from 3.5 to 5.4 MJ/m3 wastewater treated, according to biogas
production associated with each configuration. The relative reduction in CED is greater than that
observed for GWP, and varies between 16 and 86 percent for Levels 5-2 and 1, respectively.
Figure 9-7 shows that the sludge processing and disposal treatment group now contributes an
energy credit to the system, reducing the net CED of each treatment configuration.
EP-C'-16-003: WA 2-37
9-12
-------
30
- Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
° AS A20 AS 3 B5 MUCT B5/Denit MBR B5/RO MBR/RO
CHP Base CHP Base CHP Base CHP Base CHP Base CHP Base CHP Base CHP Base CHPBase
S Preliminary /Primary /Disinfection ~ Biological Treatment
0 Post-Biological Treatment ~ Sludge Processing and Disposal
~ Effluent Release ¦ Brine Injection
• Total
Figure 9-7. Cumulative Energy Demand by Treatment Group for Base Results and the
CHP Energy Recovery Sensitivity
Table 9-6 shows that acidification, PM formation, smog formation, and fossil depletion
potential all show significant reductions in system level impact in response to biogas energy
recovery. Relative reductions in impact for these four impact categories are all greater for the
lower treatment levels where absolute impact results are lower owing to lower relative energy
and material consumption. Biogas production is also greatest for Level 1 and Level 2-2, leading
to greater quantities of recovered energy. Energy recovery has a less dramatic effect on ozone
depletion and eutrophication potential impact, with relative reductions in impact potential of
between 1 and 26 percent. Eutrophi cation potential demonstrates a pattern unlike the other
impact categories, where percent reductions in eutrophication impact are greatest for the higher
treatment levels, which are associated with the lowest absolute eutrophication impact.
EP-C'-16-003: WA 2-37
9-13
-------
Section 9: Sensitivity Analysis
Table 9-6. Summary of Comparative Impact Assessment Results for the Base Case and CHP Energy Recovery Sensitivity
l.e\el 1.
l.e\el 2-
l.e\el 2-2.
1 .e\ el 3-1.
1 .e\ el 3-2.
1 .e\ el 4-1.
1 .e\ el 4-2.
1 .e\ el 5-1.
l.e\el 5-2.
linpiicl Csilcgon
Description
AS
1, \2()
\S3
155
Ml (1
Ii5/I)enil
MliK
IJ5/RO
MBK/KO
Global Warming
Potential
Base Results
0.52
0.77
0.92
1.0
0.96
1.1
1.1
1.8
1.8
CHP Sensitivity
0.25
0.54
0.61
0.81
0.74
0.92
0.91
1.6
1.5
Percent Reduction"
51%
30%
34%
21%
23%
20%
18%
13%
12%
Cumulative
Energy Demand
Base Results
5.4
9.1
14
9.7
10
12
11
24
23
CHP Sensitivity
0.75
5.0
8.2
5.8
6.4
8.4
7.7
20
19
Percent Reduction"
86%
45%
40%
40%
38%
32%
32%
18%
16%
Eutrophication
Potential
Base Results
0.07
9.8E-3
0.02
6.8E-3
6.9E-3
6.1E-3
6.8E-3
7.5E-3
7.5E-3
CHP Sensitivity
0.07
9.2E-3
0.02
6.2E-3
6.4E-3
5.6E-3
6.3E-3
6.9E-3
7.0E-3
Percent Reduction"
1%
6%
5%
8%
8%
9%
7%
8%
7%
Base Results
8.0E-4
1.5E-3
4.1E-3
1.7E-3
1.8E-3
2.0E-3
2.0E-3
0.19
0.17
Water Depletion
CHP Sensitivity
3.9E-4
1.1E-3
3.6E-3
1.3E-3
1.4E-3
1.7E-3
1.7E-3
0.19
0.17
Percent Reduction"
51%
25%
12%
21%
20%
18%
14%
0%
0%
Acidification
Potential
Base Results
0.01
0.03
0.03
0.03
0.04
0.04
0.04
0.09
0.09
CHP Sensitivity
1.1E-3
0.02
0.02
0.02
0.03
0.03
0.03
0.08
0.08
Percent Reduction"
92%
36%
44%
30%
28%
25%
21%
12%
11%
Particulate Matter
Formation
Base Results
1.5E-3
3.4E-3
3.5E-3
3.6E-3
3.9E-3
4.5E-3
4.4E-3
0.01
1.0E-2
CHP Sensitivity
1.1E-4
2.2E-3
2.1E-3
2.6E-3
2.9E-3
3.4E-3
3.5E-3
9.2E-3
9.0E-3
Percent Reduction"
93%
35%
41%
29%
27%
24%
20%
12%
10%
Smog Formation
Potential
Base Results
0.14
0.27
0.29
0.28
0.30
0.34
0.33
0.75
0.72
CHP Sensitivity
0.02
0.16
0.15
0.18
0.21
0.24
0.25
0.64
0.63
Percent Reduction"
88%
39%
46%
34%
31%
28%
25%
14%
13%
Ozone Depletion
Potential
Base Results
3.9E-6
3.8E-6
2.0E-6
7.6E-6
3.7E-6
7.4E-6
7.3E-6
7.7E-6
7.7E-6
CHP Sensitivity
3.4E-6
3.4E-6
1.5E-6
7.2E-6
3.3E-6
7.0E-6
7.0E-6
7.3E-6
7.3E-6
Percent Reduction"
12%
10%
26%
5%
10%
5%
5%
5%
5%
Base Results
0.12
0.20
0.30
0.22
0.23
0.28
0.25
0.54
0.51
Fossil Depletion
CHP Sensitivity
0.01
0.11
0.18
0.13
0.14
0.19
0.17
0.44
0.42
Percent Reduction"
89%
46%
42%
41%
39%
33%
33%
18%
17%
a - Percent Reduction = (BaseGWPimpact-CHPGWPimpact)/BaseGWPimpact
KP-C-16-003; WA 2^37
9-14
-------
Section 9: Sensitivity Analysis
9.5.3 Biogas Sensitivity L CCA
The base case LCCA results were updated to reflect the increased capital and O&M costs
associated with the installation and ongoing maintenance of a CHP system. The cost sensitivity
includes the avoided cost of reduced natural gas consumption, as well as revenue from the sale of
electricity. Equipment costs for ICE CHP generally fall in the range of $465 to $1600 per kW of
installed generation capacity (Wiser et al. 2010). The average of this range, $1033/kW, is used in
this analysis. Gas processing costs typically add $600/kW of generation capacity (Darrow et al.
2017). The same direct and indirect cost factors are applied to the CHP system as are described
in Section 2. Inclusive operation and maintenance costs are estimated per kWh of electricity
production. Gas cleaning and processing O&M costs typically range from 0.015 to 0.025 $/kWh,
while prime mover maintenance costs typically fall in the range of 0.01 to 0.025 $/kWh (Wiser et
al. 2010). The average of these reported ranges is used in this analysis, 0.02 and 0.0175 $/kWh,
respectively.
Electricity revenue is estimated using the same cost factor, $0.10/kWh, that is used to
estimate system energy cost in the main LCCA analysis. Avoided natural gas costs are based on
a natural gas purchase price of $15.50 per 1000 ft3.
Figure 9-8 summarizes the effect of including CHP and energy recovery on total system
cost. The effect on system net present value over a 30-year time horizon is relatively modest,
yielding a reduction in system net present value of between six and nine million dollars
depending upon the configuration. The relative reduction in system net present value is greatest
for level 1, yielding a 3.5 percent reduction in system net present value relative to the base
scenario that assumes flaring of biogas. Table 9-7 summarizes base case and biogas case study
life cycle costs.
Table 9-7. Summary of Biogas LCCA Costs (million 2014 $s)
Anniiiil 1
sihor.
1 IVillllHMII
Miiloriiil
iind
Anniiiil
S\slem
\e( Pivsenl \ ;iluo
( Ik-iii ic;il Cosl
Allllllill I.IK'
-!i\ Cosl
Amorli/iilion Cosl
C 'oiiTiun r:ilioii
with ( IIP
IfclSC
willi ( IIP
lisiSl'
Willi ( IIP
liilSO
Willi ( IIP
HilSC
l.e\d 1, \s
SIT
s:<)4
S4(.
S4 5
so 11
so 5l>
S i s
S i "
Level 2-1,
A20
$230
$236
$4.6
$4.5
$0.5
$0.9
$4.8
$4.8
Level 2-2,
AS3
$369
$378
$9.1
$9.0
$0.6
$1.1
$6.3
$6.2
Level 3-1, B5
$261
$267
$4.9
$4.8
$0.6
$1.0
$5.8
$5.8
Level 3-2,
MUCT
$269
$275
$4.9
$4.9
$0.7
$1.1
$6.0
$5.9
Level 4-1,
B5/Denit
$295
$301
$5.8
$5.7
$0.8
$1.2
$6.3
$6.2
Level 4-2,
MBR
$294
$285
$5.9
$5.2
$0.7
$1.1
$6.1
$6.0
Level 5-1,
B5/RO
$433
$439
$6.1
$6.0
$1.9
$2.3
$11
$11
Level 5-2,
MBR/RO
$403
$409
$5.9
$5.8
$1.9
$2.2
$10
$10
KP-C-16-003; WA 2^37
9-15
-------
Section 9: Sensitivity Analysis
500
450
400
350
300
o
w
^ 250
el
.2
% 200
150
100
50
0
m
Level 1,
AS
Level 2-1,
A20
Level 2-2, Level 3-1,
AS3 B5
Level 3-2, Level 4-1, Level 4-2, Level 5-1, Level 5-2,
MUCT B5/Demt MBR B5/RO MBR/RO
¦ withCHP DBase
Figure 9-8. Biogas Case Study Net Present Value Comparison
9.6 Retrofit Case Study
While this report displays cost results for greenfield installations, existing plants may
incorporate nutrient control technology in a retrofit. In this section, ERG conducted a case study
to investigate the potential cost implications of such a retrofit. This case study considers a retrofit
of the Level 2-1 A20 wastewater treatment configuration as the baseline (see Figure 9-9) with
the addition of chemical phosphorus removal and a denitrification filter to achieve the Level 4
target effluent nutrient concentrations of 3 mg/L total nitrogen and 0.1 mg/L total phosphorus
(see Figure 9-10).
Table 9-8 presents the total capital, total annual, and net present value for the nine
greenfield wastewater treatment configurations and the Level 2-1 greenfield wastewater
treatment configuration plus the cost for the retrofit chemical phosphorus removal and
denitrification filter (Level 2-1 to 4 Retrofit) (presented in bold). While the Level 2-1 to 4
Retrofit wastewater treatment configuration achieves the Level 4 effluent nutrient targets, the
total capital cost, total annual cost, and net present value are between the greenfield Level 2-1
A20 and both greenfield Level 3 wastewater treatment configurations. As shown in Figure 9-11,
the capital cost for the Level 2-1 to 4 Retrofit wastewater treatment configuration is $12M to
$15M lower than the greenfield Level 4 wastewater treatment configurations, but is designed to
achieve the same effluent nutrient concentrations, due to lower biological treatment and post-
EP-C'-16-003: WA 2-37
9-16
-------
Section 9: Sensitivity Analysis
biological treatment capital costs. The chemical phosphorus removal and denitrification filter
portion of the Level 2-1 to 4 Retrofit capital costs are $6.9M. As shown in Figure 9-12, the total
annual costs for Level 2-1 to 4 Retrofit are about $0.6M/yr to $0.8M/yr higher than the
greenfield Level 3 wastewater treatment configurations, but $0.3M/yr to $0.4M/yr lower than the
greenfield Level 4 wastewater treatment configurations. The annual costs for just the chemical
phosphorus removal and denitrification filter portion of the Level 2-1 to 4 Retrofit is $1.1 lM/yr.
KP-C-16-003; WA 2^37
9-17
-------
Section 9: Sensitivity Analysis
Nitrous Oxide
Emissions from
Receiving
Stream
Transportation
Emissions and Process
Figure 9-9. Level 2-1: Anaerobie/Anoxic/Oxic Wastewater Treatment Configuration (Baseline for Retrofit)
and Biodegr odation
emissions from Landfill
J
A
Hauing and
Landfilling
EP-C-l6-003; WA 2-37
9-18
-------
Section 9: Sensitivity Analysis
Figure 9-10. Level 2-1 to 4 Retrofit: Anaerobic/Anoxic/Oxic with Chemical Phosphorus Removal and Denitrification Filter
Wastewater Treatment Retrofit Configuration
EP-C-16-003; WA 2-37
9-19
-------
Section 9: Sensitivity Analysis
Table 9-8. Greenfield and Level 2-1 to 4 Retrofit Total Costs
Wastewater Treatment
Configuration
Total Capital Cost
(2014 $)
Total Annual Costa
(2014 $/yr)
Net Present Value
(2014 $)
Level 1, AS
$55,300,000
$5,140,000
$204,000,000
Level 2-1, A20
$71,400,000
$5,470,000
$236,000,000
Level 2-2, AS3
$93,100,000
$10,150,000
$378,000,000
Level 3-1, B5
$86,400,000
$5,800,000
$267,000,000
Level 3-2, MUCT
$88,900,000
$5,960,000
$275,000,000
Level 4-1, B5/Denit
$92,800,000
$6,840,000
$301,000,000
Level 4-2, MBR
$90,100,000
$6,330,000
$285,000,000
Level 2-1 to 4, Retrofitb
$78,300,000
$6,580,000
$273,000,000
Level 5-1, B5/RO
$160,000,000
$8,320,000
$439,000,000
Level 5-2, MBR/RO
$144,000,000
$8,080,000
$409,000,000
a - Total annual cost includes operational labor, maintenance labor, materials, chemicals, and energy (see Section
3.3 for details).
b - Costs are presented for the greenfield Level 2-1 plus the retrofit chemical phosphorus removal and
denitrification filter. The capital cost, annual cost, and net present value for the chemical phosphorus removal
and denitrification filter retrofit are $6.9M, $1.11M, and$37M, respectively.
$180.OM
$160M
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 2-1 Level 5-1, Level 5-2,
AS A20 AS3 B5 MUCT R5/Denit MBR to 4, B5/RO MBR/RO
Retrofit
III Preliminary/Primary/Disinfection Biological Treatment ^ Post-Biological Treatment
s Sludge Processing and Disposal = Brine Injection ¦ Other
Figure 9-11. Level 2-1 A20 Baseline and Retrofit Total Capital Costs by Aggregated
Treatment Group
EP-C'-16-003: WA 2-37
9-20
-------
Section 9: Sensitivity Analysis
$12.OM
$10.OM
| $8.0M
$6.0M
$4.0M
$2.0M
$0.0M
$5.14M
$5.47M
-H—9
m
$10.2M
$8.32M
$6.84M
$5.80M $5-96M
$6.33M
$6.58M
$8.08M
¦
i
Level 1, Level 2-1, Level 2-2, Level 3-1, Level 3-2, Level 4-1, Level 4-2, Level 2-1 Level 5-1, Level 5-2,
AS A20 A S3 B5 MUCT B5/Denit MBR to 4. B5/RO MBR/RO
Retrofit
Operation Labor i Maintenance Labor Materials ss Chemicals ¦ Energy
Figure 9-12. Level 2-1 A20 Baseline and Retrofit Total Annual Costs by Annual Cost
Category
Figure 9-13 presents relative impact results for all greenfield treatment configurations
plus the Level 2 retrofit case study. Retrofit LCI A results are generally in line with those
associated with other Level 4 treatment configurations. GWP and ozone depletion potential
lower for the retrofit case study, relative to other Level 4 treatment configurations, due to lower
estimated N20 emissions. Eutrophication impacts are slightly elevated, compared to Level 4-1
and 4-2. Table 9-9 lists summary LCIA results for all treatment levels plus the Level 2 retrofit
case study system. Retrofit results are in bold in Table 9-9.
EP-C'-16-003: WA 2-37
9-21
-------
Section 9: Sensitivity Analysis
Percent of Maximum
0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Eutrophication Potential
Cumulative Energy Demand
Global Wanning Potential
Acidification Potential
Fossil Depletion
Smog Formation Potential
Particulate Matter Formation
Ozone Depletion Potential
Water Depletion
a Level 1, AS ~ Level 2-1, A20 ~ Level 2-2, AS3
~ Level 3-1, B5 ~ Level 3-2, MUCT ~ Level 2-1 to 4, Retrofit
¦ Level 4-1, B5/Denit E3 Level 4-2, MB R ~ Level 5-1, B5/RO
BLevel 5-2, MBR/RO
Figure 9-13. Relative LCIA Results for Nine Greenfield Wastewater Treatment
Configurations and the Level 2 Retrofit Case Study
EP-C'-16-003: WA 2-37
9-22
-------
Section 9: Sensitivity Analysis
Table 9-9. Summary LCIA and Cost Results for Nine Greenfield Wastewater Treatment
Configurations and the Level 2 Retrofit Case Study (per m3 wastewater treated)
Impiicl
Csili'Sion
I nil
l.e\el 1.
AS
l.e\el 2-
1. \2()
1.e\el 2-
2. \S3
l.e\el 3-
1.155
l.e\el 3-2.
Ml ( I
l.e\el 2-
1 lo 4.
Kol rol'ii
l.nd 4-1.
Ii5/I)enil
l.nd 4-2.
MliK
1 v\ el 5-
1. 155/KO
1 .e\ el 5-2.
MBK/KO
Cost
$ USD
$0.64
$0.74
$1.18
$0.84
$0.86
$0.85
$0.94
$0.89
$1.37
$1.28
Global
Warming
Potential
kg C02 eq
0.52
0.77
0.92
1.0
0.96
0.88
1.1
1.1
1.8
1.8
Cumulative
Energy
Demand
MJ
5.4
9.1
14
9.7
10
12
12
11
24
23
Eutrophication
Potential
kg N eq
0.07
9.8E-3
0.02
6.8E-3
6.9E-3
7.3E-3
6.1E-3
6.8E-3
7.5E-3
7.5E-3
Water
Depletion
m3 H20
8.0E-4
1.5E-3
4.1E-3
1.7E-3
1.8E-3
1.9E-3
2.0E-3
2.0E-3
0.19
0.17
Acidification
Potential
kg S02 eq
0.01
0.03
0.03
0.03
0.04
0.04
0.04
0.04
0.09
0.09
Particulate
Matter
Formation
PM2.5 eq
1.5E-3
3.4E-3
3.5E-3
3.6E-3
3.9E-3
4.2E-3
4.5E-3
4.4E-3
0.01
0.01
Smog
Formation
Potential
kg 03 eq
0.14
0.27
0.29
0.28
0.30
0.32
0.34
0.33
0.75
0.72
Ozone
Depletion
Potential
kg CFC-11
eq
3.9E-6
3.8E-6
2.0E-6
7.6E-6
3.7E-6
3.4E-6
7.4E-6
7.3E-6
7.7E-6
7.7E-6
Fossil
Depletion
kg oil eq
0.12
0.20
0.30
0.22
0.23
0.26
0.28
0.25
0.54
0.51
KP-C-16-003; WA 2^37
9-23
-------
Section 10: Conclusions
10. Conclusions
This study met its goal to assess a series of wastewater treatment configurations that
reduce the nutrient content of effluent from municipal WWTPs considering treatment costs as
well as human health and ecosystem impacts from a life cycle perspective.
The LCA results highlight the trade-offs that exist between the various treatment
configurations for cost and traditional LCIA impact categories. The largest normalized impact
observed across all combinations of treatment configurations and impact categories was the
eutrophication impact for the Level 1 treatment configuration. It is clear that use of a traditional
Level 1 treatment configuration results in the lowest costs, but also significantly higher
normalized eutrophi cation impacts compared to all other study treatment system configurations.
When considering the impaired state of many of this nation's water bodies related to nutrients,
the use of nutrient removal technologies explored in this study are tools that could be used to
improve water quality. This study aims to help communities and businesses consider the
environmental and economic costs and benefits of advanced nutrient removal options.
Given the predominant contribution of electricity and energy consumption to impact
results in many of the impact categories, it is necessary to think critically about the energy
efficiency of treatment processes, particularly in relation to their level of nutrient removal. A
series of ratios are presented in Table 10-1 to help in this process. The aggregate level of nutrient
removal increases rapidly as nutrient removal standards progress from Level 1 to Level 5. The
total electricity demand that coincides with increasing levels of nutrient removal, increases
substantially across the treatment configurations, from 0.20 to 1.5 kWh/m3 wastewater treated.
However, when considering the electricity consumption compared to each unit of nutrient
removed reveals that the electricity demand does not increase across the majority of the
treatment configurations on the basis of nutrient equivalents removed. Electricity per unit of total
nitrogen and phosphorus equivalents removed remains consistent from Level 2 through Level 4.
However, due to the large electrical demand of the reverse osmosis process, total electricity per
nutrient removal is generally two to three times higher for the Level 5 treatment configurations
compared to Levels 2 through 4.
Table 10-1. Nutrient Removal Electricity Performance Metrics
1 iviilmonl l.c\cl
1
2-1
2-2
3-1
3-2
4-1
4-2
5-1
5-2
l ocil P mno\c(l ("/in')
0 <)<>
4 "
4o
4 S
4 S
4 'J
4 'J
5 u
5 (i
l ocil N mno\c(l
"
32
32
U
U
37
37
Total Electricity Demand (kWli/nf1)
0.20
0.48
0.51
0.52
0.57
0.65
0.64
1.5
1.4
Total Electrical Demand/Total P removed
(kWli/g)
N/Aa
0.10
0.13
0.11
0.12
0.13
0.13
0.30
0.29
Total Electrical Demand/Total N removed
(kWli/g)
N/Aa
0.02
0.02
0.02
0.02
0.02
0.02
0.04
0.04
a - Values not shown for Level 1 since this treatment configuration not designed for nutrient removal.
While this work was primarily focused on nutrients, the effect of study treatment
configurations on the removal of trace pollutants was also reviewed to determine if additional
benefits, not part of the original treatment design, may be realized from the implementation of
KP-C-16-003; WA 2^37
10-1
-------
Section 10: Conclusions
more advanced treatment processes. This part of the project focused on potential toxicity impacts
associated with heavy metals, toxic organics and disinfection byproducts. Results showed that
metals were by far the most influential pollutant group in terms of life cycle toxicity impacts.
Similar to nutrients, tradeoffs were identified between high effluent-based impacts at low levels
of treatment and high process-based impacts at high levels of treatment. Generally, Levels 3 and
4 (and specifically Levels 3-2 and 4-2) resulted in the lowest overall toxicity impacts, owing to
their high metal removal efficiencies and moderate material and energy requirements. Relative to
Level 4-2 in particular, the higher and more consistent degree of metal removal provided by
Level 5 was outweighed by greater process-based impacts, resulting in greater total impacts in all
toxicity categories. Results of the analysis reveal that heavy metals contribute more strongly to
human health and ecotoxicity impacts than do the toxic organics and DBPs with sufficient data
to be evaluated.
The electrical grid sensitivity analysis showed that the importance of electricity and
energy use and the trade-offs associated with achieving the key eutrophication reductions could
largely be offset if the WWTP were to utilize an electrical grid with reliance on energy sources
such as natural gas, hydro, and nuclear or use of recovered resources to generate on-site energy
in order to reduce the need for purchased electricity. While an effort to achieve reductions in the
environmental burdens associated with electricity production is certainly warranted given the
information presented in the results section, Table 10-1 provides an indication of which
treatment options may serve communities and businesses attempting to reduce environmental
impacts while simultaneously controlling energy costs. The realization of benefits associated
with these insights is not dependent on improvements in the electrical grid, which lie outside of
the control of many WWTPs. Other strategies within the facilities boundaries, such as energy
recovery from biogas, may help to offset environmental impacts from increased nutrient
removal.
Generally, the results show the benefits to eutrophication impact associated with more
stringent levels of nutrient removal. This benefit is generally increasingly offset by increases in
other environmental impacts as the standard of removal progresses from Level 2 to Level 5, with
Level 5 showing the most dramatic increase in cost and other impacts due to the exacting
standard of treatment required. However, given local and regional environmental and economic
considerations, the selection of the most appropriate treatment configuration will vary by
location. This work cannot answer the question of how much nutrient removal can be considered
sufficient for any specific WWTP or body of water. The question is inherently local or regional
in nature, and an individual or institution must consider a number of factors when trying to
determine what is appropriate for their situation. This study does indicate that careful
consideration should be given to the benefits that are expected to be gained by pursuing the more
advanced levels of nutrient removal, and that these benefits should be weighed against the
environmental and economic costs discussed in Sections 5, 6 and 7. As discussed earlier, this
study focused on the implementation of greenfield treatment configurations, and the economic
impacts may vary significantly for retrofitted operations.
Overall, this study built a comprehensive framework to assess the environmental, human
health, and cost implications of shifting to higher nutrient removal wastewater treatment
configurations. The LCCA and LCA models constructed here can be continually built upon to
improve the baseline analysis or investigate additional wastewater treatment configurations or
KP-C-16-003; WA 2^37
10-2
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Section 10: Conclusions
variability with regional conditions. The system boundaries could also be expanded to
understand the influence and potential benefit of recycling water from the effluent of the higher
nutrient removal wastewater configurations to displace production of potable water elsewhere.
KP-C-16-003; WA 2^37
10-3
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Section 11: References
11. References
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& Biorefining. 3: 42-71.
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Classification System - As Applied in Engineering, Procurement, and Construction for
the Process Industries. Recommended Practice No. 18R-97. TCM Framework: 7.3 - Cost
Estimating and Budgeting.
Ahmed, M. B., J. L. Zhou, H. H. Ngo, W. Guo, N. S. Thomaidis, and J. Xu. 2017. Progress in the
biological and chemical treatment technologies for emerging contaminant removal from
wastewater: A critical review. Journal of Hazardous Materials 323: 274-298.
doi:10.1016/j.jhazmat.2016.04.045.
Ahn, J.H., S. Kim, H. Park, B. Rahm, K. Pagilla, and K. Chandran. 2010. N2O Emissions from
Activated Sludge Processes, 2008-2009: Results of a National Monitoring Survey in the
United States. Environmental Science and Technology. 44: 4505-4511.
Alberta Environment. 2007. Quantification Protocol for the Anaerobic Decomposition of
Agricultural Materials Project: Excel Biogas Calculator.
http://environment. gov.ab.ca/info/library/7917.pdf Accessed 5 April, 2016
Alexander, J. T., F. I. Hai, and T. M. Al-aboud. 2012. Chemical coagulation-based processes for
trace organic contaminant removal: Current state and future potential. Journal of
Environmental Management 111: 195-207.
Alfonsin, C., A. Hospido, F. Omil, M. Moreira, and G. Feijoo. 2014. PPCPs in wastewater —
Update and calculation of characterization factors for their inclusion in LCA studies.
Journal of Cleaner Production 83: 245-255.
Alvarino, T., S. Suarez, J. Lema, and F. Omil. 2018. Understanding the sorption and
biotransformation of organic micropollutants in innovative biological wastewater
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Appendix A: Wastewater Treatment Configurations
APPENDIX A
SELECTION OF WASTEWATER TREATMENT CONFIGURATIONS
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Appendix A: Wastewater Treatment Configurations
Appendix A: Selection of Wastewater Treatment Configurations
ERG searched the literature to compile performance information on wastewater treatment
configurations which remove both TN and TP from municipal wastewater. ERG recorded the
type of biological treatment used and the use or absence of chemical addition for phosphorus
precipitation, fermenter, sand filter, and other technology components. ERG assumed
preliminary treatment with screens, a grit chamber, and primary clarification. Sludge
management was assumed to include gravity thickening, anaerobic digestion, dewatering
(centrifugation), and transport of wastewater solids to a landfill. ERG gathered performance data
from nine key sources:
• Bickler, S. Wigen Water Technologies. 2015. Technical Feedback Requested
Regarding Reverse Osmosis. Email from S. Bickler, to A. Allen, ERG. (June).
• Bott, C. and Parker, D. 2011. Nutrient Management Volume II: Removal Technology
Performance & Reliability. Water Environment Research Federation Report
NUTRlR06k. IWA Publishing, London, U.K.
• Dukes, S. and von Gottberg, A. Koch Membrane Systems. 2006. Membrane
Bioreactors for RO Pretreatment. Water Environment Foundation. WEFTEC® 2006.
• Eastern Research Group, Inc. 2009. Draft Technical Support Document: Analysis of
Secondary Treatment and Nutrient Control at POTWs. (December).
• Eastern Research Group, Inc. 2015b. Personal communication between Amber Allen,
Debra Falatko, and Mark Briggs of ERG and Stacey Bickler of Wigen Water
Technologies.
• Falk, M.W., Neethling, J.B., and Reardon, D.J. 2011. Striking the Balance Between
Nutrient Removal in Wastewater Treatment and Sustainability. Water Environment
Research Federation Report NUTRlR06n. IWA Publishing, London, U.K.
• Hartman, P. and Cleland, J. ICF International. 2007. Wastewater Treatment
Performance and Cost Data to Support an Affordability Analysis for Water Quality
Standards. Montana Department of Environmental Quality. (May). Available online
at http://www.kvsq.org/docsAVastewater_2007.pdf.
• Tetra Tech. 2013. Cost Estimate of Phosphorus Removal at Wastewater Treatment
Plants. Ohio Environmental Protection Agency. (May). Available online at
http://epa.ohio.gov/Portals/35/wqs/nutrient_tag/OhioTSDNutrientRemovalCostEstim
ate_05_06_l 3 .pdf.
• U.S. EPA OWM. 2008b. Municipal Nutrient Removal Technologies Reference
Document. EPA 832-R-08-006. Washington, DC. (September). Available online at
http://water.epa.gov/scitech/wastetech/upload/mnrt-volumel.pdf.
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Appendix A: Wastewater Treatment Configurations
• U.S. EPA OST. 2015a. A Compilation of Cost Data Associated with the Impacts and
Control of Nutrient Pollution. EPA 820-F-l 5-096. Washington, DC. (May). Available
online at http://www2.epa.gov/sites/production/files/2015-04/documents/nutrient-
economics-report-2015 .pdf.
ERG recorded performance data for all wastewater treatment configurations and assigned
each a performance level as defined in Falk et al. (2011), Table ES-1:
• Level 1 - No target effluent concentration specified;
• Level 2-8 mg N/L, 1 mg P/L;
• Level 3 - 4-8 mg N/L, 0.1-0.3 mg P/L;
• Level 4-3 mg N/L, 0.1 mg P/L; and
• Level 5 - 2 mg N/L, <0.02 mg P/L.
In many cases, performance levels for wastewater treatment configurations differ for TN
and TP (i.e., a configuration achieves a certain level for TN and a different level for TP).
ERG examined the set of identified wastewater treatment configurations for which TN
and TP performance levels match to identify nine which are commonly used and provide
contrast. Contrast was defined by differences in terms of performance level, type of biological
nutrient reduction, combinations of additional treatment steps, costs (capital and operating), and
other contrasting parameters such as energy requirements, chemical usage, and sludge
generation. For level 1, ERG recommended one wastewater treatment configuration, and for
each of levels 2 to 5 ERG recommended two wastewater treatment configurations. ERG's
rationale for these recommendations is described below.
A.l Results and Recommendations
ERG identified 37 wastewater treatment configurations that achieve the same
performance level for both TN and TP (see Table A-l). The technologies used in these
wastewater treatment configurations include a variety of biological nutrient removal and
enhanced nutrient removal technologies.
The sections below describe the wastewater treatment configurations identified for each
performance level and discuss ERG's rationale for selection of specific wastewater treatment
configurations to be evaluated in the LCA. Selected configurations generally represent those
most commonly used to achieve the desired performance levels, and that also provide contrast in
biological processes, capital and/or annual costs, or other factors such as energy requirements
and sludge generation. The most common reasons wastewater treatment configurations were not
selected include: 1) they are unique retrofits and otherwise not commonly used, 2) they are very
similar to another selected technology, or 3) they exhibit a wide range of performance, spanning
multiple performance levels, which raises uncertainty as to the reliability with which the process
can achieve a specific performance level.
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Appendix A: Wastewater Treatment Configurations
Table A-l. Identified Wastewater Treatment Configurations
Recommended wastewater treatment configuration
All configurations assumed to also include preliminary/primary treatment and sludge management.
No.
Type of Biological
Treatment
Phosphorus
Precipitation
Fermenter
Sand Filter
Additional
Treatment
Long Term
Average
Effluent TN
Concentrati
on (mg/L as
N)
TN
Level
Long Term
Average
Effluent
TP
Concentrat
ion (mg/L)
TP
Level
Performance Source 1
1
3-stage Westbank
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
2
3-stage Westbank
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
3
4-stage Bardenpho
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
4
5-stage Bardenpho
(Level 3)
X
X
X
4 to 8
2,3
0.1 to 0.3
3
b, Table 3-1 and 2-b,
pages 56, 57, 59.
5
5-stage Bardenpho
(Level 4)
X
X
X
Denitritication filter
3
4
0.1
4
b, Table 3-1 and 2-b,
pages 56, 57, 60-61; also
a, Table 5-d, page 237
6
5-stage Bardenpho
X
X
3
4
0.1
4
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
7
5-stage Bardenpho
(Level 5)
X
Not listed in
reference
(Falk et al),
but may be
appropriate
X
Denitritication filter
(10% flow) +
ultrafiltration and
reverse osmosis (90%
flow)
<2
5
<0.02
5
b, Table 3-1 and 2-b,
pages 56, 57, 61; also a,
Table 5-d, page 237
8
Activated sludge +
Modified Ludzack-
Ettinger
Biological activated
filter
4
3
<=0.3
3
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
9
Activated sludge +
Modified Ludzack-
Ettinger
X
3
4
0.1
4
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
10
Activated sludge
(Level a, assuming
conventional activated
sludge treatment)
3 to 9
a,2,3
0.3 to 2
a,2
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
EP-C'-16-003: WA 2-37
A-3
-------
Appendix A: Wastewater Treatment Configurations
Table A-l. Identified Wastewater Treatment Configurations
Recommended wastewater treatment configuration
All configurations assumed to also include preliminary/primary treatment and sludge management.
No.
Type of Biological
Treatment
Phosphorus
Precipitation
Fermenter
Sand Filter
Additional
Treatment
Long Term
Average
Effluent TN
Concentrati
on (mg/L as
N)
TN
Level
Long Term
Average
Effluent
TP
Concentrat
ion (mg/L)
TP
Level
Performance Source 1
11
Activated sludge, 3-
sludge system (Level
2)
X
6 to 8
2
0.43
2
a, pages 2-5 and 3-5/6
(pg 59 and 151/152)
12
Aerobic lagoons
3 to 8
2,3
0.1 to 1
2,3
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
13
Anaerobic/Anoxic/Oxi
c (Level 2)
8; 3 to 8
2; 2,3
1; 0.5 to 1
2; 2
b, Table 3-1 and 2-b,
pages 56, 57, 58.;
a, Table 5-d, page 237
14
Anaerobic/Oxic,
Phoredox
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
15
Cyclic activated sludge
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
16
Integrated fixed-film
activated sludge
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
17
Extended aeration
3 to 8
2,3
0.1 to 1 (2)
2,3
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
18
Facultative lagoon
3 to 8
2,3
0.1 to 1
2,3
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
19
Membrane bioreactor
(Level 4)
X
<3
4
<=0.1
4
a, Table 5-d, page 237
20
Membrane bioreactor
(Level 5)
X
Not listed in
reference
(Falk et al),
but may be
appropriate
Reverse osmosis (85%
flow)
<2; <0.1
5
<0.02; -
5
b, Table 3-1 and 2-b,
pages 56, 57, 61; a,
Table 5-d, page 237; 8,
page 6127; 9, page 1
EP-C'-16-003: WA 2-37
A-4
-------
Appendix A: Wastewater Treatment Configurations
Table A-l. Identified Wastewater Treatment Configurations
Recommended wastewater treatment configuration
All configurations assumed to also include preliminary/primary treatment and sludge management.
No.
T\ |K' nl' liinlii^ii;il
Tl'i';ilmilll
Phiisphiirus
Pivi'ipihiiiun
IVniu-iiliT
Siiiul l-'ilkT
A(l(liliiui;il
Tiv;ilnu-nl
l.mi" Term
1.Illuuil I N
(iiiuininili
1111 (m»/l. ;is
N)
IN
IamI
l.mi" Term
A\er;i»e
Kllliieiil
IP
(uiHinlnil
inn (m»/l.)
IP
l.lMl
PerliirmiiiHe Si hi in- 1
21
Membrane bioreactor
X
Land application/
infiltration bed
<3
4
<=0.1
4
a, Table 5-d, page 237,
also land application
note on pages 13d, 27,
and 39
22
Modified Ludzack-
Ettinger
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
23
Modified Ludzack-
Ettinger
X
X
X
Denitrification filter
<3
4
<=0.1
4
a, Table 5-d, page 237,
page 63
24
Moving-bed biofilm
reactor (Level 2)
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
25
Phased isolation ditch
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
26
Pho Strip II
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
21
Post-aeration anoxic
with methanol (Blue
Plains process, a
retrofit system)
X
3 to 8; 4 to 8
2,3
0.5 to 1;
0.18
2; 3
a, Table 5-d, page 237;
7, page 3-43 (pg 83)
28
Rotating biological
contactor (assume
Level 3 performance)
3 to 8
2,3
0.1 to 1
2,3
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
29
Sequencing batch
reactor
3 to 8
2,3
0.1 to 1
2,3
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
30
Sequencing batch
reactor
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
31
Sequencing batch
reactor
X
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
32
Step-feed activated
sludge
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
KP-C-16-003; WA 2^37
A-5
-------
Appendix A: Wastewater Treatment Configurations
Table A-l. Identified Wastewater Treatment Configurations
Recommended wastewater treatment configuration
All configurations assumed to also include preliminary/primary treatment and sludge management.
No.
Type of Biological
Treatment
Phosphorus
Precipitation
Fermenter
Sand Filter
Additional
Treatment
Long Term
Average
Effluent TN
Concentrati
on (mg/L as
N)
TN
Level
Long Term
Average
Effluent
TP
Concentrat
ion (mg/L)
TP
Level
Performance Source 1
33
Step-feed activated
sludge (Level 4)
X
X
X
Chemically assisted
clarification
<3
4
<=0.1
4
a, Table 5-d, page 237
34
Trickling filter
Submerged biological
filter
3
4
0.1
4
c, Figure IV-9, page IV-
11 (pg 58), Figure IV-
16, page IV-17 (pg 64),
page E-l (pg 97)
35
Suspended growth
activated sludge
X
X
Inclined plate settling
tanks, deep bed sand
filter
3 to 6
3
0.18
3
d, page 3-39 (pg 79-80)
36
University of Cape
Town process,
modified
3 to 8
2,3
0.5 to 1
2
a, Table 5-d, page 237
37
University of Cape
Town process,
modified (Level 3)
X
X
X
<3
3
0.1 to 0.5
3
a, Table 5-d, pages 5-5
(Pg 237), ES-22 (pg 40),
UCTm equivalent to
technologies in Table 5-
2 on page 5-4 (pg 236)
1 - Sources: a - U.S. EPA OWM, 2008b; b - Falk et al„ 2011; c - U.S. EPA OST, 2015a; d- Bott and Parker, 2011.
2 - This phosphorus removal capability is unexpected, but is included as reported in the cited wastewater treatment configuration source document.
EP-C'-16-003: WA 2-37
A-6
-------
Appendix A: Wastewater Treatment Configurations
A. 1.1 Level 1
Level 1 technologies are not designed to specifically remove nutrients, although some
removal of nutrients occurs with the wastewater treatment configuration. ERG recommended the
conventional plug flow activated sludge system to represent level 1 performance.
A. 1.2 Level 2
Twenty-two wastewater treatment configurations performed at level 2 for both TN and
TP. These wastewater treatment configurations included the biological and enhanced nutrient
reduction technologies listed in Table A-l. ERG selected the anaerobic/anoxic/oxic (A20)
system as a typical level 2 wastewater treatment configuration and then reviewed the remaining
level 2 wastewater treatment configurations for contrast, performance, and likelihood of use.
ERG considered and rejected the moving-bed biofilm reactor because it is most
frequently used as a retrofit but otherwise is not commonly used. The integrated fixed-film
activated sludge and anaerobic/oxic Phoredox systems were rejected as too similar to the
selected A20 system. The Modified University of Cape Town process and 4-stage Bardenpho
were rejected at level 2 to allow for their selection as contrasting wastewater treatment
configurations for other performance levels.
The sequencing batch reactor, 3-stage Westbank, cyclic activated sludge, step-feed
activated sludge, phased isolation ditch, modified Ludzack-Ettinger (MLE), and PhoStrip II were
rejected due to concerns that their performance ranges were too wide, raising uncertainty
regarding their ability to reliably achieve level 2 performance. The extended aeration system was
rejected because of concerns about the performance data presented in the reference. The Blue
Plains Process was rejected because it is a unique retrofit system. The aerobic and facultative
lagoons were rejected because lagoons are not applicable for all publicly owned treatment works
(POTWs). A rotating biological contactor (RBC) system was initially considered because it
offers the advantages of low energy usage, low solids generation, and good settling. However,
the RBC technology was ultimately rejected because its use is predominately restricted to small
plants; the technology also exhibited a number of problems in the 1970s and 1980s, some of
which remain unresolved today.
After eliminating the other level 2 options for the reasons discussed above, ERG
recommended a common alternative level 2 configuration of plug flow activated sludge followed
by separate stage nitrification and separate stage denitrification with chemical phosphorus
removal. This technology contrasts with the recommended A20 system in its relative ease of
operation and control (due to segregated treatment components for BOD, ammonia, and nitrate
removal) and relatively higher cost due to multiple biological reactors and associated
clarifiers/sludge recycling.
In summary, ERG recommended the following two technologies to represent level 2
performance in the LCA:
• 2-1) A20 with chemical phosphorus precipitation; and
• 2-2) 3-Sludge activated sludge system with chemical phosphorus precipitation.
KP-C-16-003; WA 2^37
A-7
-------
Appendix A: Wastewater Treatment Configurations
A. 1.3 Level 3
Ten wastewater treatment configurations performed within the level 3 range. Of these, six
were rejected from further consideration because their TN/TP performance spans levels two and
three (included in the level 2 description above). The remaining four wastewater treatment
configurations perform at level 3 for both TN and TP. The first system, which uses activated
sludge, MLE, and a biological activated filter, was not recommended because it is a unique
retrofit system. The second system, which uses suspended growth in high purity oxygen
activated sludge, inclined plate setting tanks, and a deep bed sand filter, was rejected because
suspended growth systems are not applicable for all POTWs. The remaining two systems are
commonly used systems that ERG recommended to represent level 3 performance in the LCA:
• 3-1) 5-Stage Bardenpho with chemical phosphorus precipitation, fermenter, and sand
filter; and
• 3-2) Modified University of Cape Town process with chemical phosphorus
precipitation, fermenter, and sand filter.
A. 1.4 Level 4
Eight wastewater treatment configurations perform at level 4 for both TN and TP. These
processes included a 5-stage Bardenpho activated sludge coupled with a MLE unit, 4- and 5-
stage Bardenpho systems coupled with membrane filtration, denitrification filters coupled with a
MLE unit or with a 5-stage Bardenpho, a trickling filter coupled with a submerged biological
filter, and a step-feed activated sludge process with chemically assisted clarification. Most of
these wastewater treatment configurations also include chemical phosphorus precipitation, and
half also include either a fermenter or a sand filter.
ERG selected the 5-stage Bardenpho with denitrification filter as a typical level 4
wastewater treatment configuration. For the contrasting level 4 wastewater treatment
configuration, ERG considered and rejected the membrane bioreactor with land infiltration and
the trickling filter because neither is applicable for all POTWs. The activated sludge coupled
with a MLE unit was rejected as a unique retrofit system. The 5-stage Bardenpho without
denitrification filter was rejected as too similar to the typical level 4 configuration. Of the
remaining three options (step-feed activated sludge, MLE with denitrification filter, and 4-stage
Bardenpho with membrane filter), ERG selected the membrane bioreactor (MBR) system as a
contrasting alternative because of its increasing popularity.
In summary, ERG recommended the following technologies to represent level 4
performance in the LCA:
• 4-1) 5-Stage Bardenpho with chemical phosphorus precipitation, fermenter, sand
filter, and denitrification filter; and
• 4-2) 4-Stage Bardenpho MBR and chemical phosphorus precipitation.
A. 1.5 Level 5
Two wastewater treatment configurations performed at level 5 for both TN and TP. The
first configuration includes 5-stage Bardenpho, chemical precipitation, and fermentation. The
KP-C-16-003; WA 2^37
A-8
-------
Appendix A: Wastewater Treatment Configurations
wastestream is then split with a portion of the flow undergoing side stream treatment by reverse
osmosis (RO) and the remainder of the flow undergoing side stream treatment by a
denitrification filter and sand filter. The second wastewater treatment configuration is a 5-stage
Bardenpho MBR with chemical phosphorus precipitation and fermenter followed by a portion of
the flow to RO and the remainder of the flow not requiring additional side stream treatment. This
second process is a modification of the first, substituting a 5-stage Bardenpho MBR for the 5-
stage Bardenpho and clarifier. The MBR allows the wastewater treatment configuration to
achieve similar TN and TP performance without a denitrification filter and sand filter.
ERG conducted additional literature reviews and communications with RO vendors to
determine RO pretreatment requirements. For the first configuration, RO pretreatment includes
solids removal (ultrafiltration, UF), biofouling control (chlorination followed by dechlorination),
and scale control (antiscalant addition). RO pretreatment for the second configuration is similar
to the first, except that use of the 5-stage Bardenpho MBR precludes the need for solids removal
via UF.
ERG performed calculations to determine the percentage of flow requiring side stream
treatment for each configuration to achieve the target TN and TP effluent concentrations. For
TN, ERG assumed the following effluent quality achieved by nutrient control technologies:
• A 5-stage Bardenpho TN effluent concentration of 4 - 8 mg/L (based on the
performance of the level 3 5-stage Bardenpho configuration).
• A denitrification and sand filter TN effluent concentration of 3 mg/L (based on the
performance of the level 4 5-stage Bardenpho configuration).
• A 5-stage Bardenpho MBR TN effluent concentration of 3 mg/L (based on the
performance of the level 4 5-stage Bardenpho MBR configuration).
• A RO removal of 95 percent (based on information from RO vendors).
Using these assumptions, and a target overall TN effluent concentration of 2 mg/L,
approximately 35 to 40 percent of flow would need to undergo side stream treatment by RO.
For TP, ERG assumed the following effluent quality achieved by nutrient control
technologies:
• A 5-stage Bardenpho TP effluent concentration of 0.1 to 0.3 mg/L (based on the
performance of the level 3 5-stage Bardenpho configuration).
• A denitrification and sand filter TP effluent concentration of 0.1 mg/L (based on the
performance of the level 4 5-stage Bardenpho configuration).
• A 5-stage Bardenpho MBR TP effluent concentration of 0.1 mg/L (based on the
performance of the level 4 5-stage Bardenpho MBR configuration).
• A RO removal of 95 percent (based on information from RO vendors).
KP-C-16-003; WA 2^37
A-9
-------
Appendix A: Wastewater Treatment Configurations
Using these assumptions, and a target overall TP effluent concentration of 0.02 mg/L,
approximately 85 to 90 percent of flow (for the second and first configurations, respectively)
would need to undergo side stream treatment by RO.9
These calculations demonstrate that TP removal, rather than TN removal, drives the
percentage of wastewater requiring RO treatment to achieve level 5 performance.
In summary, ERG recommended the following technologies to represent level 5
performance in the LCA:
• 5-1) 5-stage Bardenpho with chemical phosphorus precipitation, fermenter, and sand
filter followed by 10 percent of the flow to a denitrification filter and sand and 90
percent of the flow to UF and RO; and
• 5-2) 5-stage Bardenpho MBR with chemical phosphorus precipitation and fermenter
followed by 85 percent of the flow to RO.
A summary of these recommendations is found in Table A-2 below.
Table A-2. Recommended Technologies
Perforniiince
l.e\el
T\ |H' of liiolo^iciil
1 IVilllllOlll
Phosphorus
Precipiliilion
l-'crmcnler
SillKl
Tiller
Oilier Tcchniciil
( omponcnls
Reference
1
Plug Flow Activated
Sludge
OST, 2015
2
Anaerobic/Anoxic/Oxic
Fa Ik. 2011
2
Activated Sludge, 3-
Sludge System
X
OWM, 2008
3
5-Stage Bardenpho
X
X
X
Fa Ik. 2011
3
University of Cape
Town Process, Modified
X
X
X
OWM, 2008
4
5-stage Bardenpho
X
X
X
Denitrification
Filter
Fa Ik. 2011
4
4-stage Bardenpho
MBR
X
OWM, 2008
5
5-Stage Bardenpho
X
X
X
10%:
Denitrification
Filter
90%: UF and RO
Fa Ik. 2011
and OWM,
2008
5
5-stage Bardenpho
MBR
X
X
85% RO
Fa Ik. 2011
and OWM,
2008
9 Note that RO effluent quality expressed as a percentage of TP removal may not be the most appropriate measure of
RO performance, but rather an effluent concentration of non-detect (detection limit 0.02 mg/L). Under this scenario,
assuming an average effluent concentration equal to the detection limit, Vi the detection limit, and zero,
approximately 80 to 100 percent of flow would need to undergo side stream treatment by reverse osmosis.
KP-C-16-003; WA 2^37
A-10
-------
Appendix A: Wastewater Treatment Configurations
A.2 Technology Selection Data Quality
In accordance with the project's Quality Assurance Project Plan (QAPP) entitled Quality
Assurance Project Plan for Life Cycle and Cost Assessments of Nutrient Removal Technologies
in Wastewater Treatment Plants (ERG, 2015c) approved by EPA on March 25, 2015, ERG
collected existing data10 via a literature search to determine the performance of identified
wastewater treatment configurations. The literature search focused on peer-reviewed literature,
EPA projects, and publicly available equipment specifications from and communications with
technology vendors. ERG evaluated the collected information for completeness, accuracy, and
reasonableness. In addition, ERG considered publication date, accuracy/reliability, and nutrient
concentrations (reported as TN and TP) when reviewing data quality. Finally, ERG performed
conceptual, developmental, and final product internal technical reviews of the data compilation
and this Appendix.
Completeness. The descriptions of wastewater treatment configurations in the literature
vary in level of detail. Descriptions used in this analysis were limited to those sufficiently
detailed to be classified into one of the performance level categories and to identify the major
technology components (e.g., type of biological treatment, chemical treatments, sand filter).
ERG reviewed the treatment system descriptions, and did not include data for incomplete
treatment systems.
Accuracy. ERG evaluated sources to ensure that the descriptions of each treatment
system represent current operations at municipal treatment systems, and that nutrient reductions
reflect the performance of the identified control technologies rather than other design or
operational factors.
Reasonableness. ERG evaluated sources to ensure that the type of treatment correlates
with expected nutrient reduction performance; for example, treatment systems with nutrient
control should have lower nutrient concentrations than systems with secondary treatment only.
The criteria ERG used in evaluating the quality of information collected during the
literature review are summarized in Table A-3.
Table A-3. Literature Review Data Quality Criteria
Qu;ili(\ (rilerion
Ik'scripl ion/Definition
Current (up to date)
Report the time period of the data.
Year of publication (or presentation, if a paper presented at a conference) is 2005 or after.
Accurate/Reliable
U.S. government publications assumed accurate.
For academic researcher:
• Publication in peer reviewed journal.
• Presentation at professional technical conference.
For vendor researcher:
• Publication in peer reviewed journal.
10 Existing data means information and measurements that were originally produced for one purpose that are
recompiled or reassessed for a different purpose. Existing data are also called secondary data. Sources of existing
data may include published reports, journal articles, LCI and government databases, and industry publications.
KP-C-16-003; WA 2^37
A-ll
-------
Appendix A: Wastewater Treatment Configurations
Table A-3. Literature Review Data Quality Criteria
Qu;ili(> ( rik'i ion
IK'sc riplinn/lk-rinil ion
Analyte Scope
Nutrient concentrations, reported as TN and TP.
In accordance with the QAPP, ERG performed conceptual, developmental, and final
product technical reviews of the spreadsheet included as Table A-l. These reviews included the
following general steps:
• The spreadsheet developer verified the accuracy of any data that were transcribed into
the spreadsheet;
• The team member reviewer also verified the accuracy of any data that were
transcribed into the spreadsheet;
• The team member reviewer evaluated the technical soundness of methods and
approaches used;
• The ERG spreadsheet developer maintained version control of interim spreadsheets;
and
• The ERG spreadsheet developer maintained documentation in the project files.
KP-C-16-003; WA 2^37
A-12
-------
Appendix B: Metals
APPENDIX B
DETAILED CHARACTERIZATION OF HEAVY METALS BEHAVIOR IN
STUDY TREATMENT CONFIGURATIONS
KP-C-16-003; WA 2^37
-------
Appendix B: Metals
Appendix B: Detailed Characterization of Heavy Metals Behavior in Study
Treatment Configurations
B.l Introduction
The discharge of metals to the environment represents an ever-present concern, given
their potential toxicity at even trace levels. Wastewater treatment plants (WWTP) receive
variable but sometimes high loads of metals depending on the mix of sources in their watershed,
which can include industrial activities, domestic sources and stormwater (Yost et al. 1981; Rule
et al. 2006; J.-M. Choubert et al. 201 lb). Given a WWTP's position as a final barrier between
source and environmental discharge, they are an opportunity for smart management of
potentially toxic substances like metals.
The direct management of metals in conventional, municipal WWTPs has traditionally
not been a focus of WWTP design and operation as measures like the National Pretreatment
Program11 are in place to limit the concentration and load of metals coming from industrial
facilities. Rather, most discussion surrounding the treatment of metals by municipal WWTPs has
dealt with the ancillary benefits afforded by existing processes that impact metals as well as the
organics and nutrients these processes were designed to address (Choubert et al. 201 la;
Choubert et al. 201 lb; Ziolko et al. 2011; Cantinho et al. 2016). Additionally, little to no
attention has been paid to the life cycle impacts of metal emissions associated with upstream
processes, especially in conjunction with and relative to direct effluent emissions. To date, the
most comprehensive study performed to address the 'co-benefits' of various treatment processes
from a life cycle perspective only qualitatively discussed the effects of metals from both
upstream and direct discharge impact calculations (Rahman et al. 2018). This study is therefore
intended to address these gaps, which will help to both characterize the ability of a variety of
commonly used wastewater treatment practices to partition metals from the liquid phase, as well
as to help inform the full potential benefits of these treatment trains from a comprehensive life
cycle perspective.
The metals reviewed for this study were selected based on two main criteria: the metal's
recurrent presence in lists of regulated substances and its prevalence in the literature regarding
treatability in the study treatment configurations. Indirectly, these two criteria were assumed to
be indicators of demonstrated potential of the metal to cause environmental or human health
impacts. The resulting list of metals includes Cadmium (Cd), Chromium (Cr), Copper (Cu),
Mercury (Hg), Nickel (Ni), Lead (Pb), and Zinc (Zn). Each of these metals have been regulated
in different countries. Four of them (Cd, Hg, Ni and Pb) were classified by the European Water
Framework Directive (EUWFD) as priority substances and two (Hg and Cd) were additionally
classified as hazardous substances (EU 2013; Cantinho et al. 2016). In the United States (US),
guidance is provided for concentration limits of each of these metals in WWTP effluent through
National Recommended Water Quality Criteria (EPA 2009). Table B-l summarizes relevant
regulatory criteria for the metals included in this study. Metal concentrations in land-applied
sludge are also regulated in the US through the Part 503 Rule (NRC 2002).
https://www.epa.gov/npdes/national-pretreatment-program
KP-C-16-003: WA 2-37 B-l
-------
Appendix B: Metals
Elevated levels of metals in the environment can result from both natural and
anthropogenic sources. In the urban environment, metals are present in mixed municipal
wastewater owing to the contribution of commercial and industrial sources, residential sources,
contact with piping, and stormwater runoff (Yost et al. 1981; Thornton et al. 2001; Jones et al.
2017). Often, domestic inputs tend to be the largest sources of Cu, Zn and Pb, whereas
commercial and industrial sources contribute greater proportions of Hg and Cr (Makepeace et al.
1995; Cantinho et al. 2016). Table B-l summarizes ranges of influent concentrations established
in several literature reviews, along with the ranges that were compiled from the case study data
reviewed as part of this effort. These concentrations, as well as concentrations throughout this
document, represent total concentrations (as opposed to specific fractions) unless otherwise
noted.
Table B-l. Summary of Literature and Case Study Metal Influent Concentrations and
Regulatory Effluent Concentrations
Value
I'll
(u
CoilCCII
/.II
trillions
Ni
in nii/l.
Ci-
( (1
ll»
Soles
Source
Influent
Concentrations -
Literature
Reviews
5.7
63
181
11
10
0.21
0.36
19 Plants,
France
1
25
78
155
14
12.0
0.8
0.5
30 Plants, UK
2
140-600
—
—
—
—
—
—
Combined WW
3
232
489
968
455
378
19
—
12+ Cities, US
4
Case
Study
Ranges
High
68
118
493
77
290
10
7.0
This Study
5
Mediu
m
21
65
350
24
59
4.9
3.8
This Study
5
Low
10.8
25
204
11
19
0.94
0.37
This Study
5
US CCCa
2.5
9
120
52
74/1 lb
0.25
0.77
Effluent Limits
6
US CMC3
65
13
120
470
570/16b
2
1.4
Effluent Limits
6
a - Criterion Continuous Concentration/Criteria Maximum Concentration, hardness dependent except for Cr (VI)
and Hg. Values shown assume a hardness of 100 mg/L.
b - Chromium (III/VI)
1 - Choubert et al., 201 lb; Ruel et al., 2012
2 - Rule et al., 2006
3 - Metcalf and Eddy, 2014
4 - Yostetal., 1981
5 - Linstedt et al., 1971; Brown et al., 1973; Chen et al., 1974; Oliver and Cosgrove, 1974; Aulenbach and Chan,
1988; Huang et al., 2000; Innocenti et al., 2002; Chipasa, 2003; Karvelas et al., 2003; Qdais and Moussa,
2004; Buzier et al., 2006; da Dilva Oliveira et al., 2007; Mohsen et al., 2007; Obarska-Pempkowiak and
Gajewska, 2007; Carletti et al, 2008; Johnson et al., 2008; Dialynas and Diamadopoulos, 2009; Renman et
al., 2009; Malamis et al., 2012; Arevalo et al., 2013; Garcia et al., 2013; Salihoglu, 2013; Inna et al., 2014;
Reddy et al., 2014
6-U.S. EPA, 2019b
KP-C-16-003; WA 2^37
B-2
-------
Appendix B: Metals
B.2 Metal Chemistry
With the exception of Cr, the metals selected in this study are commonly found in the 2+
oxidation state (Huang et al. 2000). Chromium mainly occurs in the Cr(III) and Cr(VI) oxidation
states. While the Cr(VI) form is more labile and toxic to a number of organisms, it is generally
associated with industrial effluent and is therefore less prevalent in both raw municipal
wastewater and WWTP effluent (Jan and Young 1978; Stasinakis et al. 2003; Stasinakis and
Thomaidis 2010). Moreover, Cr(VI) can be reduced to Cr(III) in the presence of suitable electron
donors (e.g., organic substrates), whereas experimental results have shown that Cr(III) is not
oxidized to Cr(VI) under the aerobic conditions found in AS plants (Stasinakis et al. 2003). A
possible explanation is that oxidation of Cr(III) may be so slow that biosorption occurs before
any oxidation can occur (Schroeder and Lee 1975).
With respect to treatability, the fraction in which the metal exists (solid or dissolved) is
more important than its oxidation state which, under average municipal wastewater conditions,
tends not to vary. Throughout the wastewater treatment process, metals generally exist in
precipitated (strong complex), organically complexed (weak complex) or soluble forms (Nelson
et al. 1981; Huang et al. 2000; Buzier et al. 2006). The type and fraction of precipitates present,
which are considered insoluble and often the strongest of the complexes, depend on pH,
solubility of the metal species, and the availability of complexing reagents including hydroxides,
carbonates, and phosphates (Stoveland and Lester 1980; Huang et al. 2000; Wang et al. 2006).
However, the solubility coefficients and products of metals reported in the literature vary
markedly (Cheng et al. 1975) and direct application to study systems may not be appropriate as
site-specific calculated solubilities can be up to two orders of magnitude different than
experimental determinations (Nelson et al. 1981; Parker et al. 1994).
The unprecipitated fraction of metals tend to form weak organic complexes, which can be
both settleable or dissolved (distinguished by the fraction passing through a 0.45 |im filter). The
process of metal ion sorption to organic material is typically referred to as biosorption, and its
effectiveness varies with the type of metal, ambient water quality, and the source of the organic
material (Cheng et al. 1975; Huang et al. 2000; Arican et al. 2002; Chang et al. 2007). With the
exception of Ni and Cd, which show an intermediate and variable affinity to solids partitioning
(Cheng et al. 1975; Wang et al. 2006), the study metals tend to readily adsorb to particulate
matter in raw, mixed municipal wastewater (mean dissolved fractions below 30%) (Goldstone et
al. 1990a; Goldstone et al. 1990b; Goldstone et al. 1990c; Buzier et al. 2006; Choubert et al.
201 lb). Accordingly, processes that remove solids or metal-organic complexes are often
effective at removing metals as well.
Extracellular polymers (ECPs) have been found to play a key role in biosorption (Brown
and Lester 1979; Hunter et al. 1983; Lawson et al. 1984; Norberg and Persson 1984; Rudd et al.
1984) as they contain negatively charged functional groups such as phosphoryl, carboxyl,
sulphydryl, and hydroxyl groups which can serve as adsorption sites (Kelly et al. 1979; Nelson et
al. 1981). Additionally, the metal affinity of ECPs has been shown to depend on the
microorganism (MO) or MO consortium that produced them. In general, slower growing MOs
produce more ECPs (Nelson et al. 1981; Hunter et al. 1983; Ghosh and Bupp 1992).
Operationally, solids retention time (SRT) is typically used (along with ambient redox and
nutrient conditions) to hold the bacterial growth rate constant, which in turn maintains consistent
KP-C-16-003; WA 2^37
B-3
-------
Appendix B: Metals
sorption characteristics of the biosolids. Conversely, increasing the SRT tends to select for
slower-growing MOs, which in turn can increase the metal sorption capacity of the biosolids
(Stensel and Shell 1974; Chao and Keinath 1979; Nelson et al. 1981). For example, the floe
produced by slow-growing phosphate accumulating organisms (PAOs) and denitrifying
organisms (DNOs) that are selected for in biological nutrient removal (BNR) processes with high
SRTs have been found to have greater affinity towards Cd and Ni than conventional activated
sludge floe (Chang et al. 2007). Notably, biosorption is a passive process taking place on the
order of minutes to hours and does not depend on the viability of biological floe (Cheng et al.
1975; Neufeld and Hermann 1975; Nelson et al. 1981); the influence of active metabolic
processes can therefore be considered unimportant (Huang et al. 2000). Moreover, for this study,
hydraulic retention time (HRT) is maintained on the order of hours rather than minutes and will
likely have little effect on the removal of metals by the different treatment levels.
Dissolved organic matter (DOM), for which COD can be considered a surrogate, also has
a significant effect on metal sorption by biosolids (Sterritt and Lester 1983; Rudd et al. 1984;
Tien and Huang 1991). High DOM can prevent both metal precipitation and metal uptake by
sludge particulates by lowering ambient pH and competing for sorption sites, respectively
(Cheng et al. 1975; Lo et al. 1989). In a detailed study of the factors influencing metals removal
in four full-scale conventional activated sludge (AS) wastewater treatment (WWT) systems,
Huang et al. (2000) found COD and SS concentrations to be the most important as indicators of
effective biosorption of the dissolved fraction to biosolids, and biosolids removal, respectively.
B.3 Fate of Metals During Wastewater Treatment
The fate of metals during wastewater treatment depends on a number of chemical,
physical, and operational parameters of the treatment process. Many processes commonly found
in municipal wastewater treatment plants result in the effective removal of certain metals from
the liquid fraction, thus limiting emissions to receiving waters. Depending on the type of unit
processes present, the metals removed from the liquid fraction are partitioned to either the solids
(sludge) fraction or in the case of this study where reverse osmosis is used, the brine solution.
Although volatilization was proposed as a loss pathway for Hg in the early wastewater treatment
literature (Yamada et al. 1969), results from full-scale systems indicate that this is likely an
artifact of startup conditions. In continuously operating full scale WWTPs, adsorption to biomass
is the dominant partitioning mechanism and volatilization is negligible (Goldstone et al. 1990c;
Pomies et al. 2013).
In general, metal concentrations tend to decrease during primary treatment. Metals
present as precipitated species or adsorbed to settleable solids (i.e. the non-dissolved fraction) are
the main fractions that are removed. As such, many authors have found a correlation between
primary treatment solids removal and metal removal, with reported metal removals ranging from
40-70% when solids removal is high (Rossin et al. 1982; Lester 1983; Kempton et al. 1987).
However, where primary solids removal is lower or concentrated supernatant is recirculated to
the headworks (in effect increasing internal, dissolved metal loadings), reported total metal
removals can be on the order of 1-10% (Oliver and Cosgrove 1974) and can even be negative
depending on the strength of recirculated supernatant (Huang et al. 2000; Inna et al. 2014). Due
to the variability of this documented performance, the similarity of primary treatment unit
processes and the incorporation of internal circulation within most study configurations, it was
KP-C-16-003; WA 2^37
B-4
-------
Appendix B: Metals
conservatively assumed that no metals removal was directly attributed to primary treatment.
Primary treatment performance was instead aggregated with secondary biological processes,
both because proper functioning of secondary processes implicitly assumes proper primary
treatment or pretreatment, and because most performance data obtained for secondary processes
implicitly accounted for the presence of standard primary treatment.
In secondary biological unit processes, SRT, COD, and TSS tend to be important
indicators of metals partitioning (Lo et al. 1989; Huang et al. 2000). Systems that provide better
COD removal tend to allow for greater sorption potential between metals and biological floes,
which can then be removed through efficient suspended solids removal. The sorption process
varies by metal type as well, depending on the affinity of metal species to sludge and the stability
of the sludge metal complexes. Results from batch equilibrium adsorption experiments using
solids from conventional activated sludge (CAS) systems indicate that the stability constants of
the sludge-metal complexes follow the order of Hg(II)~Pb(II)~Cu(II)~Cr(II)>Zn(II)>
Cd(II)>Ni(II) (Wang 1997). This is supported by results from full scale case studies as well, with
removals of Hg, Pb, Cu, Cr, Cd, and Zn often in the range of 40-60% and the removal of Ni
often less than 40% for sorption-based processes like CAS (Lester 1983; Cantinho et al. 2016).
For more advanced biological treatment processes like Bardenpho or Modified University Cape
Town (MUCT) systems, much less work has been done to characterize the biosorption and
metals partitioning dynamics, however the limited case studies available suggest that due to the
greater SRT, COD removal and diversity of microbial consortiums (and by extension variety of
metal-binding ECPs), overall metal removal performances are marginally better than CAS,
ranging from approximately 60-80%) for all metals except Cd and Ni, which are around 30-40%
(Chipasa 2003; Obarska-Pempkowiak and Gajewska 2007; Salihoglu 2013; Emara et al. 2014).
Aside from potential detection limit influences on full removal potentials, no mechanistic
explanations of the lower Cd and Ni removal efficiencies were given (Chipasa 2003; Salihoglu
2013)
Following biological treatment, advanced filtration in the form of sand filters, MBR, and
RO can be effective in physically removing the remaining soluble or colloidal fractions, as well
as what remains of the insoluble fraction. Of the three, sand filters tend to be the least effective,
owing to the larger pore spaces through which water can travel. Still, as a tertiary treatment
process, removals of remaining organics can be on the order of 10-50%), and metals 0-3 5%
(Linstedt et al. 1971; Aulenbach and Chan 1988; Renman et al. 2009). Next, MBRs have proven
very effective as a tertiary polishing step, with removals of most metals on the order of 50%> to
greater than 95%> (Innocenti et al. 2002; Carletti et al. 2008; Dialynas and Diamadopoulos 2009;
Malamis et al. 2012; Arevalo et al. 2013). Last, with the smallest effective pore size, RO is the
most effective unit process for metals removal with the case study literature indicating consistent
removal efficiencies of 90%> or greater (Dialynas and Diamadopoulos 2009; Malamis et al. 2012;
Arevalo et al. 2013; Garcia et al. 2013).
For this study there are also several unit processes that through either limited,
contradictory or inconclusive evidence, were not assigned any removal credit. Chemical
phosphorus precipitation is a unit process that can be effective at removing metals, however it is
dependent upon the chemicals used for precipitation and the conditions of the plant. In a study of
three WWTPs using only alum or sodium aluminate for enhanced phosphorus removal,
Aulenbach et al. (1984) found statistically insignificant effects for Pb and Cr removal and only a
EP-C-I6-QQ3; WA 2^37
B-5
-------
Appendix B: Metals
minor benefit to Cu removal (less than a 10% difference), noting that Cd, Hg, and Zn were
removed to undetectable levels prior to alum dosing. Accordingly, chemical phosphorus
precipitation using alum salts alone (U9, Table B-2) was not considered to provide an additional
metals removal benefit.
The metals removal performance of tertiary biological nutrient removal processes,
including nitrification reactors, denitrification reactors and tertiary clarification, has also not
been extensively researched. Conceptually, the additional contact time between remaining
soluble metal species and a new, distinct biological consortium (compared to upstream
secondary unit processes) could reasonably be thought to provide for additional metals removal.
However, in a study using copper as an indicator of the comparative metal removing
performance of tertiary vs. secondary WWTPs, Inna et al. (2014) found that while tertiary
processes like biological aerated flooded filters and nitrifying trickling filters provided some
degree of additional copper removal, the tertiary return flows tended to have adverse and
somewhat unpredictable effects on the performance of upstream unit processes. While they
found total removal efficiencies of 57% for the three secondary plants and 78% for the two
tertiary plants with nitrifying filters, the removal attributed directly to the nitrifying trickling
filters was just 11% (-15%) to 37%>). Given the lack of information obtained for other metals, the
marginal performance documented by Inna et al. (2014) and the potential for adverse effects
from concentrated return flows, tertiary biological nutrient removal processes (U11-U14) were
assumed to have no net effect on metals.
KP-C-16-003; WA 2^37
B-6
-------
Appendix B: Metals
Table B-2. Unit Process Composition of Study Treatment Configurations
\\ iislowiilor 1 iviilmonl (onl'i
-------
Appendix B: Metals
Table B-2. Unit Process Composition of Study Treatment Configurations
\\ iislowiilor 1 iviilmonl ( onfiiiiir;i(inn
I nil Process
l.e\el 1.
AS
l.c\el
2-1.
\2()
¦J J)
\S3
l.oel
3-1.
155
l.e\el
3-2.
Ml (1
l.c\el
4-1.
l)5/IH-nil
loci
4-2.
\1I)R
l.e\el
5-1.
1)5/KO
l.o\ol
5-2.
MDK/KO
1:4
Sludge Anaerobic Digestion
V
y
V
V
y
V
V
y
V
U25
Sludge - Centrifugation
V
V
V
V
V
V
V
V
V
U26
Sludge - Haul and Landfill
V
V
V
V
V
V
V
V
V
U27
Brine - Underground Inject
V
V
•J Indicates unit process is relevant for select wastewater treatment configuration,
a - Periodic chemical cleaning is included for all membranes.
b - Membrane bioreactor wastewater treatment configurations use a membrane filter for the solid-liquid separation process instead of a traditional
secondary clarifier.
c - This configuration includes two instances of tertiary clarification.
d - Includes chlorination and dechlorination pretreatment.
KP-C-16-003; WA 2^37
B-8
-------
Appendix B: Metals
B.4 Metals Removal Performance Estimation Methods
Metal removal efficiencies for study system configurations were estimated based on a
detailed literature review of performance results from similar systems. Sources reviewed include
peer-reviewed literature, government reports and book chapters, covering a range of bench-scale
experiments to performance characterization of full-scale treatment systems. Given the
complexity of conditions and partitioning processes that can occur within WWTPs, empirical
results were prioritized where the demonstrated metals removal performance of comparable
treatment configurations or unit processes could be used to estimate performance of the study
configurations. Where possible, mechanistic discussion was provided, though it is qualitative in
nature as the factors affecting metal partitioning and removal are highly site specific (Cheng et
al. 1975; Nelson et al. 1981; Huang et al. 2000) and mechanistic modelling is beyond the
capability of the existing CAPDETWorks models used to develop the LCA and cost analysis.
For system levels where no representative equivalent was identified but the important
components were characterized, a composite removal efficiency was calculated based upon case
study performance data of its major unit processes. For example, Level 3-1 includes a 5-stage
Bardenpho process with subsequent sand filtration. However, results of the literature review only
identified 5-stage Bardenpho WWTPs without sand filtration. Therefore, Equation B-l below
represents a two-step linear process and was used to combine these results with removal
efficiencies identified for sand filtration as a standalone process.
Rtotal = fi^i + /2 (1 ^1)^2
Equation B-l
where
Rtotai = composite metal removal efficiency
fi = fraction of flow diverted to process 1
Ri = removal efficiency of process 1
f2 = fraction of flow diverted to process 2
i?2 = removal efficiency of process 2
In this example, Ri would be representative of the combined effects of Ul, U2, U6, and
U10 (pretreatment + 5-stage Bardenpho + secondary clarification), while R2 would be
representative of U17 (sand filter). The functional form has also been adapted to account for
more than two stepwise processes (e.g. Level 5-2) or parallel streams (e.g. Level 5-1), as
demonstrated below. Note that the unit code descriptions are provided in Table B-2.
B.5 Metals Removal Performance Estimation Results
Following the approach outlined in Section B.4, Table B-3 shows how removal
efficiencies for each study configuration were calculated based on major unit process
combinations and supporting literature. Final composite removal efficiencies for each metal, by
treatment configuration, are provided in Table B-4 and illustrated in Figure B-l. A more detailed
discussion of each treatment configuration follows.
EP-C-I6-QQ3; WA 2^37
B-9
-------
Appendix B: Metals
Table B-3. Summary of Composite Removal Calculations used in Equation 1
l.lMl
l.i-M-l I nil I'll ins sis'
C;im- Sliul\ I nil
Pnni-ssii-s)1'
ir
P1
IK'siripiion
Level 1, AS
U1+U2+U4+U10
U1+U2+U4+U10
N/A
100%
Conventional Activated Sludge6
Level 2-1, A20
U1+U2+U5+U10
U5
q
100%
Anaerobic/Anoxic/
Oxicf
Level 2-2, AS3
U1+U2+U4+U9+XJ10+U11+U12+U13
U1+U2+U4+U10
q
100%
3-Sludge System8
Level 3-1, B5
Ul+U2+[/5+U6+[/9+U10+U17
U1+U2+U6+U10
R1
100%
5-stage Bardenpho11
U17
R2
100%
Sand filter1
Level 3-2, MUCT
Ul+U2+[/5+U8+[/9+U10+U17
U1+U2+U8+U10
R1
100%
Modified University Cape Town processJ
U17
R2
100%
Sand filter1
Level 4-1, B5/Denit
m+m+u3+m+u9+m^ui4+mi
U1+U2+U6+U10
R1
100%
5-stage Bardenpho11
U17
R2
100%
Sand filter1
Level 4-2, MBR
Ul+U2+U7+[/9+U15
U7
q
100%
4-stage Bardenphok
U15
R2
100%
Membrane bioreactor1
Level 5-1, B5/RO
Ul+U2+[/5+U6+[/9+U10+W4+U17+U18
+U19
U1+U2+U6+U10
R1
100%
5-stage Bardenpho11
U17
R2a
10%
Sand filter1
U18
R2b
90%
Reverse osmosis111
Level 5-2, MBR/RO
Ul+U2+t/J+U6+t/9+U15HJ18
U1+U2+U6+U10
R1
100%
5-stage Bardenpho11
U15
R2
100%
Membrane bioreactor1
U18
R3
85%
Reverse osmosis111
a - Bold unit processes affect metals removal, italicized unit processes were determined to have no significant effect,
b - Unit process or unit process configurations represented in the case study literature.
c - Removal efficiency determined from the literature and used in stepwise removal calculations (see Equation B-l. 'NA' indicates that Equation B-l was not used, as documented
removal efficiencies could be used directly to represent the entire treatment system, 'q' indicates that only qualitative conclusions can be drawn from the applicable literature,
d - Proportion of flow directed to unit process(es), see Equation B-l.
e - Brown et al., 1973; Oliver and Cosgrove, 1974; da Silva Oliveira et al., 2007; Carletti et al., 2008; Karvelas et al., 2003
f - Chang et al., 2007
g - Metal-affecting unit processes same as Level 1, use Level 1 for conservative estimation
h - Salihoglu et al., 2013
i - Linstedt et al., 1971; Aulenbach and Chan, 1988; Renman et al., 2009; Reddy et al., 2014
j - Chipasa, 2003; Obarska-Pempkowiak and Gajewska, 2007. Data describe the metals removal performance of membrane bioreactors. Data were assumed to be representative of
membrane filtration as well, as the physical filtration is the dominant partitioning mechanism of metals sorbed to dissolved organic complexes,
k - Emara et al., 2014
1 - Innocenti et al., 2002; Carletti et al., 2008; Dialynas and Diamadopoulos, 2009; Malamis et al., 2012; Arevalo et al., 2013
m - Dialynas and Diamadopoulos, 2009; Malamis et al., 2012; Garcia et al., 2013; Arevalo et al. 2013
KP-C-16-003; WA 2^37
B-10
-------
Appendix B: Metals
Table B-4. Summary of Estimated Metal Removal Efficiencies3
Melsil
l.e\el 1
AS
l.e\el 2-1
\2<)
l.e\el 2-2
AS3
l.e\el 3-1
155
l.e\el 3-2
Ml (1
l.e\el 4-1
Ii5/I)enil
l.e\el 4-2
MliK
1 .e\ el 5-1
IJ5/UO
1 .e\ el 5-2
MliK/KO
Cu
Min
35%
35%
35%
75%
52%
75%
68%
93%
96%
Mean
62%
62%
62%
80%
77%
80%
90%
97%
99%
Max
84%
84%
84%
83%
96%
83%
99%
98%
100%
Pb
Min
40%
40%
40%
55%
39%
55%
68%
95%
97%
Mean
65%
65%
65%
66%
70%
66%
88%
96%
99%
Max
97%
97%
97%
75%
94%
75%
100%
97%
100%
Ni
Min
16%
16%
16%
42%
66%
42%
64%
82%
91%
Mean
39%
39%
39%
45%
67%
45%
82%
90%
97%
Max
91%
91%
91%
47%
68%
47%
100%
94%
100%
Zn
Min
12%
12%
12%
57%
83%
57%
75%
94%
97%
Mean
42%
42%
42%
72%
89%
72%
85%
96%
99%
Max
77%
11%
77%
83%
94%
83%
91%
98%
99%
Cd
Min
11%
11%
11%
40%
23%
40%
96%
93%
99%
Mean
59%
59%
59%
47%
41%
47%
97%
94%
100%
Max
83%
83%
83%
57%
59%
57%
98%
95%
100%
Cr
Min
16%
16%
16%
78%
88%
78%
83%
97%
99%
Mean
64%
64%
64%
81%
88%
81%
91%
98%
100%
Max
79%
79%
79%
84%
89%
84%
95%
98%
100%
Hg1
Min
17%
17%
17%
17%
17%
17%
93%
84%
98%
Mean
53%
53%
53%
53%
53%
53%
97%
93%
100%
Max
85%
85%
85%
85%
85%
85%
99%
98%
100%
a - "Removal Efficiency" used loosely; data more explicitly represents partitioning to sludge. Min and max represent minimum and maximum removal
efficiencies reported in the literature. Where removal efficiencies are composites of multiple processes, minimum represents the composite of both
contributing minimums, likewise for maximum.
b - No data for Hg removal found for 4-stage Bardenpho, 5-stage Bardenpho or MUCT. Therefore, conservatively assumed same removal for these
biological treatment processes as documented for CAS (Levell). Data for Levels 4-2, 5-1 and 5-2 represent the effect of tertiary polishing step
alone, i.e. MBR and RO.
KP-C-16-003; WA 2^37
B-ll
-------
Appendix B: Metals
100%
fl 80%
O O S> V1 \r V V
100%
K"^t
fl 80%
v n ^ n ^ \> V V V" \r V V
100%
K"^t
fl 80%
1)
60%
F^
<+H
W
9 40%
O
§ 20%
pi
o%
I
I
Ni
\\ n^ 'V^' N.^" JV
V\>v,vvvvvv
100%
60%
s 80%
• 2
o
<+H
W
* 40%
>
o
§ 20%
pi
o%
100%
fl 80%
^ rw-Tl' k^N VyV ^jV
Cd vs> s> \> O sr sr v v
100%
60%
K"^t
fl 80%
• 2
o
<+H
w
* 40%
o
§ 20%
Pi
0%
i
Cr
\\ q ^ r» o>^ o> [sA ty^ Cv^
v\>\^VV\ry*VV>
I
\% rt ^ rt ry^" fv^ N.^" N.^ Cv^
Hg v\> O sr Vs v v3
a - Distinct bar patterns are used to distinguish treatment systems in each of the five nutrient removal levels,
b - Error bars represent the minimum and maximum removal efficiencies reported in the literature.
Figure B-l. Summary of Estimated Metal Treatment Performance3'b
EP-C'-16-003: WA 2-37
B-12
-------
Appendix B: Metals
B. 5.1 Level 1: Conventional Plug Flow Activated Sludge (AS)
Level 1 is the most commonly represented treatment configuration within the case study
literature. Overall, seven conventional activated sludge (CAS) systems were reviewed providing
a range of performance results. Metals with the highest mean removals were Pb, Cr and Cu, each
with a mean removal >60%. Intermediate mean removals of 40-60% were determined for Cd, Hg
and Zn, while Ni returned the lowest mean removal of 39%. This pattern is to be expected, with
previous reviews showing good (>50%) removals of Cd, Cr, Cu and Pb, and lower removals
(<30%) for Ni (Stephenson and Lester 1987). For all metals, variability in results was high, with
ranges from less than half to more than double the mean for most metals.
B. 5.2 Level 2-1: Anaerobic/Anoxic/Oxic (A20)
Level 2-1 is differentiated from Level 1 by its three-stage biological nutrient removal
system which consists of sequential anaerobic, anoxic, and oxic basins. No performance data for
A20 systems were found in the literature review, however a study conducted to determine the
metal affinity of A20 sludge was reviewed (Chang et al. 2007). While data were not provided
that could provide an input/output removal performance, results indicated that A20 sludge
exhibited higher biosorption affinities than CAS sludge for Cd and Ni, and similar affinity for Zn
(only three metals were evaluated). Based on these relative conclusions and in combination with
the slightly longer SRT (Table 1-5) and better removal performance of COD (Table 1-4), it was
conservatively assumed that the metal removal performance of Level 2-1 was equivalent to
Level 1.
B. 5.3 Level 2-2: Activated Sludge, 3-Sludge System (A3S)
Level 2-2 is similar to Level 1, with the addition of post-secondary suspended growth
nitrification and denitrification reactors, as well as chemical phosphorus precipitation. No
performance data for A3S systems were found in the literature review. Despite the greater SRT
(Table 1-5) and better removal performance of COD (Table 1-4), in the absence of literature
specifically documenting effects of this process on metal concentrations, it was conservatively
assumed that the metal performance of Level 2-2 was equivalent to Level 1.
B. 5.4 Level 3-1: 5-Stage Bardenpho System (B5)
Level 3-1 is characterized by a combination of case studies that are representative of its
major metal-affecting unit processes, including the 5-stage Bardenpho process and sand
filtration. Salihoglu (2013) reviewed the metals removal performance of two WWTPs that
utilized the 5-stage Bardenpho process in the Turkish city of Bursa. The treatment plants, which
serve populations of 170,000 and 85,000 in mixed urban areas, consist of pretreatment (screening
and grit removal) followed by an equalization tank, 5-stage Bardenpho process and a clarifier. In
terms of applicability to Level 3-1, the plants describe the beginning of the treatment train
including pretreatment (Ul), 5-stage Bardenpho process (U6) and secondary clarification (U10).
Although primary sedimentation (U2) is not included, it is assumed that the level of treatment
conferred by the particular combination of unit processes (U1+U6+U10) allows for sufficient
settleable solids removal such that the absence of U2 can be considered negligible.
Data for sand filtration came from a range of studies, including pilot- or bench-scale tests
of sand filtration as a tertiary treatment unit process (Linstedt et al. 1971; Aulenbach and Chan
EP-C-16-003; WA 2-37
B-13
-------
Appendix B: Metals
1988), as a polishing step for septic effluent (Renman et al. 2009) and for the treatment of
stormwater (Reddy et al. 2014). Although stormwater is compositionally different than
wastewater, it is arguably closer to secondary effluent than raw wastewater and the inclusion of
these results helped fill data gaps left by the wastewater-specific studies.
Reported removal efficiencies for the 5-stage Bardenpho system for all metals except Cd
and Pb (data were not given for Hg) tended to be similar to those reported for CAS, while the
removal efficiency for Cd was lower than CAS and Pb was higher (Salihoglu 2013). No
mechanistic explanations were provided for these deviations by Salihoglu (2013), though
possible reasons may have to do with the relatively high affinity of Pb and relatively low affinity
of Cd to organic matter, respectively (e.g., Wang, 1997) Mean removal efficiencies for sand
filtration case studies ranged from 2% to 29%, bounded by Cr (2%) and Ni (3%) at the low end
and Pb (22%) and Zn (29%) at the high end. Composite removal efficiencies for L3-1 were
greater than Level 1 for all metals except Cd (and Hg, as no data were reported for U6 or U17
unit processes), owing to low removals of Cd in both 5-stage Bardenpho (41%) and sand
filtration (11%).
B.5.5 Level 3-2: Modified University of Cape Town (MUCT)
Level 3-2 is characterized by a combination of case studies that are representative of its
major metal-affecting unit processes, including the Modified University of Cape Town process
and sand filtration. Metals performance data for MUCT systems come from a pair of case studies
conducted in Poland (Chipasa 2003; Obarska-Pempkowiak and Gajewska 2007). The first
system, reviewed by Chipasa (2003), includes screening and grit removal (Ul), primary
sedimentation (U2), MUCT reactors (U8), and secondary clarification (U10). The second
system, reviewed in Obarska-Pempkowiak and Gajewska (2007), refers to a 23 MGD plant
receiving mixed municipal wastewater with roughly 10% coming from industrial sources.
Primary treatment consists of screening, an aerated sand trap and primary sedimentation, which
was assumed equivalent to screening and grit removal (Ul) and primary sedimentation (U2).
Biological treatment consists of six sequential reactors that make up the MUCT process (U8)
followed by secondary sedimentation (U10).
Data for sand filtration come from a range of studies, including pilot- or bench-scale tests
of sand filtration as a tertiary treatment unit process (Linstedt et al. 1971; Aulenbach and Chan
1988), as a polishing step for septic effluent (Renman et al. 2009) and for the treatment of
stormwater (Reddy et al. 2014). Although stormwater is compositionally different than
wastewater, it is arguably closer to secondary effluent than raw wastewater and the inclusion of
these results helped fill data gaps left by the wastewater-specific studies.
Mean removal efficiencies for the MUCT systems ranged from 66% to 88% with the
exception of Cd, which had a mean removal of 34%. Mean removal efficiencies for sand
filtration case studies ranged from 2% to 29%, bounded by Cr (2%) and Ni (3%) at the low end
and Pb (22%) and Zn (29%) at the high end. Composite removal efficiencies for Level 3-2 were
slightly better than Level 3-1 for Pb, Zn, Ni and Cr and slightly worse for Cu and Cd. No data
were reported for Hg.
EP-C-I6-QQ3; WA 2^37
B-14
-------
Appendix B: Metals
B. 5.6 Level 4-1: 5-Stage Bardenpho System with Denitrification Filter (B5/Denit)
The unit process configuration of Level 4-1 is identical to Level 3-1, with the exception
of an attached growth denitrification reactor. Although no data were identified to directly
characterize the metals removal performance of this unit process, it is likely that it provides some
degree of metals removal as it allows for additional contact time between secondary effluent and
a new, biologically distinct consortium. However, in the absence of literature specifically
documenting effects of an attached growth denitrification reactor on metal concentrations, it was
conservatively assumed that the performance of Level 4-1 was equivalent to that of Level 3-1.
B. 5.7 Level 4-2: 4-Stage Bardenpho Membrane Bioreactor System (MBR)
Level 4-2 is characterized by a 4-stage Bardenpho system followed by a membrane
bioreactor. The 4-stage Bardenpho system of Level 4-2 differs from the 5-stage Bardenpho
system of Level 4-1, lacking the first anaerobic stage and having a total SRT of 19 days as
opposed to 15 days for the 5-stage system. No data were found characterizing the metals
performance of a 4-stage Bardenpho system, rather performance was estimated based on the
comparative design and operation of the study configurations as well as results from a bench-
scale study performed to directly compare the performance of 4-stage and 5-stage Bardenpho
systems using Ni and Fe as indicators of metal removal (Emara et al. 2014). The study showed
that after incorporation of the upstream anaerobic tank, thus modifying the 4-stage to a 5-stage
system, Ni removal increased from 68% to 86% and Fe removal increased from 82% to 92%.
This is to be expected, as the incorporation of the anaerobic stage is done to improve phosphorus
removal through the promotion of phosphorus accumulating organisms, which produce floe that
provides for an additional degree of biosorption. As such, it was conservatively assumed that the
metal removal efficiency of the 4-stage system was 50% of the 5-stage system described by
Salihoglu (2013). The greater SRT of the Level 4-2, 4-stage system compared to the Level 4-1,
5-stage system, adds a further degree of conservatism as it would suggest better performance
than what is being assumed.
The metals removal performance of MBRs has been well characterized, with five
applicable studies identified representing six different systems (Innocenti et al. 2002; Carletti et
al. 2008; Dialynas and Diamadopoulos 2009; Malamis et al. 2012; Arevalo et al. 2013). The
systems all treated mixed municipal primary effluent, ranged in size from a 100 gpd pilot plant to
a 5.3 MGD full-scale plant, and had membrane pore sizes of either 0.020 |im or 0.040 |im.
Average removal efficiencies across all studies were high, ranging from 76% (Ni) to 96% (Cd
and Hg). That the removals are high relative to other unit processes discussed thus far is
reasonable when considering the pore size of MBRs (0.020 to 0.040 |im) relative to the filter
pore size generally used to delineate between dissolved and non-dissolved fractions (0.45 |im).
This comparison suggests an ability to remove smaller dissolved organic complexes in the 0.04-
0.45 |im range that may be missed by processes that rely on settling or clarification.
Although a conservative assumption was made regarding the treatment performance of
the 4-stage Bardenpho system, composite removal efficiencies for the Level 4-2 configuration
are greater than those of Level 4-1 for all metals reviewed, owing to the high removal efficiency
of the MBR unit process. Moreover, although Hg was not included in any Bardenpho study, the
two MBR studies that did evaluate Hg found an average removal of 96%, which could
reasonably be interpreted as a total Hg removal efficiency for Level 4-2.
EP-C-16-003; WA 2-37
B-15
-------
Appendix B: Metals
B. 5.8 Level 5-1: 5-Stage Bardenpho with Sidestream Reverse Osmosis (B5/R0)
Level 5-1 is characterized by a 5-stage Bardenpho system followed by two parallel
processes. The first, treating 90% of the 5-stage Bardenpho effluent, consists of an ultrafilter
followed by a reverse osmosis (RO) system. The remaining 10% is treated by a sand filter,
similar to Level 3-1.
For the 5-stage Bardenpho system, Salihoglu (2013) reviewed the metals removal
performance of two WWTPs that utilize this process in the Turkish city of Bursa. The treatment
plants, which serve populations of 170,000 and 85,000 in mixed urban areas, consist of
pretreatment (screening and grit removal) followed by a selector tank, 5-stage Bardenpho
process and a clarifier. In terms of applicability to Level 5-1, the plants describe the beginning of
the treatment train including pretreatment (Ul), 5-stage Bardenpho process (U6) and secondary
clarification (U10). Although primary sedimentation (U2) is not included, it is assumed that the
level of treatment conferred by the particular combination of unit processes (U1+U6+U10)
allows for sufficient settleable solids removal that the absence of U2 can be considered
negligible.
For the first parallel process, consisting of an ultrafilter followed by an RO system, four
studies were found evaluating the performance of five distinct RO systems (Qdais and Moussa
2004; Dialynas and Diamadopoulos 2009; Malamis et al. 2012; Garcia et al. 2013). The systems
reviewed were mostly pilot scale treating mixed municipal primary effluent, with the exception
of a 0.3 MGD full scale system (Garcia et al. 2013) and a pilot scale study evaluating synthetic
industrial wastewater (Qdais and Moussa 2004). Ultrafiltration was not explicitly included as, in
the case of most case study systems and study configurations, this step serves as a pretreatment
step allowing for proper RO functioning and its performance was generally not characterized.
Mean removal of each metal across all systems for which data were available were greater than
90%. The lowest removal efficiencies reported for any single system, and the only rates less than
90%), were those for the pilot plant treating pretreated, mixed municipal wastewater evaluated by
Malamis et al. (2012) at 82%> for Cu and 76%> for Ni.
Data for sand filtration come from a range of studies, including pilot- or bench-scale tests
of sand filtration as a tertiary treatment unit process (Linstedt et al. 1971; Aulenbach and Chan
1988), as a polishing step for septic effluent (Renman et al. 2009) and for the treatment of
stormwater (Reddy et al. 2014). Although stormwater is compositionally different than
wastewater, it is arguably closer to secondary effluent than raw wastewater and the inclusion of
these results helped fill data gaps left by the wastewater-specific studies.
Composite removal efficiencies for Level 5-1 are 90-98%> for all metals reviewed. Also,
although sufficient data were not obtained for the full characterization of Hg removal in 5-stage
Bardenpho or RO systems, Ruel et al. (2011) measured effluent concentrations in two full-scale
municipal WWTPs that incorporated RO for advanced nutrient removal and found Hg to be
below the level of detection in both cases.
EP-C-I6-QQ3; WA 2^37
B-16
-------
Appendix B: Metals
B. 5.9 Level 5-2: 5-Stage Bardenpho Membrane Bioreactor with Sidestream Reverse Osmosis
(MBR/RO)
Level 5-2, the most advanced study configuration, consists of a 5-stage Bardenpho
system followed by an MBR, then treatment of 85% of MBR effluent by an RO system with the
remaining 15% discharged with no further treatment.
For the 5-stage Bardenpho system, Salihoglu (2013) reviewed the metals removal
performance of two WWTPs that utilized this process in the Turkish city of Bursa. The treatment
plants, which serve populations of 170,000 and 85,000 in mixed urban areas, consist of
pretreatment (screening and grit removal) followed by a selector tank, 5-stage Bardenpho
process and a clarifier. In terms of applicability to Level 5-2, the plants describe the beginning of
the treatment train including pretreatment (Ul), 5-stage Bardenpho process (U6) and secondary
clarification (U10). Although primary sedimentation (U2) is not included, it is assumed that the
level of treatment conferred by the particular combination of unit processes (U1+U6+U10)
allows for sufficient settleable solids removal that the absence of U2 can be considered
negligible.
The metals removal performance of MBRs has been well characterized, with 5 applicable
studies identified representing 6 different systems (Innocenti et al. 2002; Carletti et al. 2008;
Dialynas and Diamadopoulos 2009; Malamis et al. 2012; Arevalo et al. 2013). The systems all
treated mixed municipal primary effluent, ranged from a 100 gpd pilot plant to a 5.3 MGD full-
scale plant and had membrane pore sizes of either 0.020 |im or 0.040 jam. Average removal
efficiencies across all studies were high, ranging from 76% (Ni) to 96% (Cd and Hg). That the
removals are high relative to other unit processes discussed thus far is reasonable when
considering the pore size of MBRs (0.020 to 0.040 jam) relative to the filter pore size generally
used to delineate between dissolved and non-dissolved fractions (0.45 |im). This comparison
suggests an ability to remove much smaller, dissolved organic complexes missed by processes
that rely on settling or clarification.
For the characterization of RO systems, four studies were found evaluating the
performance of 5 distinct RO systems (Qdais and Moussa 2004; Dialynas and Diamadopoulos
2009; Malamis et al. 2012; Garcia et al. 2013). The systems reviewed were mostly pilot scale
treating pretreated mixed municipal wastewater, with the exception of a 0.3 MGD full scale
system (Garcia et al. 2013) and a pilot scale evaluating synthetic industrial wastewater (Qdais
and Moussa 2004). Ultrafiltration was not explicitly included as, in the case of most case study
systems and study configurations, this step serves as a pretreatment step allowing for proper RO
functioning and its performance was generally not characterized. Mean removal of each metal
across all systems for which data were available were greater than 90%. The lowest removal
efficiencies reported for any single system, and the only rates less than 90%, were those for the
pilot plant treating pretreated, mixed municipal wastewater evaluated by Malamis et al. (2012) at
82%) for Cu and 76% for Ni.
Composite removal efficiencies for Level 5-2 are 97% to >99% for all metals reviewed.
Also, although sufficient data were not obtained for the full characterization of Hg removal in 5-
stage Bardenpho or RO systems, Ruel et al. (2011) measured effluent concentrations in two full-
scale municipal WWTPs that incorporated RO for advanced nutrient removal and found Hg to be
below the level of detection in both cases.
EP-C-I6-QQ3; WA 2^37
B-17
-------
Appendix B: Metals
B.6 Heavy Metals Toxicity Characterization Factors
Table B-5 presents the characterization factors used to estimate toxicity impacts
associated with heavy metals in treatment plant effluent and sludge. Not all heavy metals
included in this study have associated characterization factors listed in the most recent versions
of USEtox™, versions 2.02 and 2.11. Characterization factors that were not otherwise available
were estimated using the median value of all other heavy metals for which data was available.
Sources for individual characterization factors are listed in Table C-8.
Table B-5. Heavy Metals Toxicity Characterization Factors, USEtox™ version 2.11
l"ivslm;ili-r
;.i'iilii\kil\.
1 luiiiiiii 1 k;illli i;uuvr.
lliiniiin lk;illli niiiHiiiHi'i'.
(( I I 1-. I'M
I'ivslm;ik-r (C"
1 h, i:isi-s/k»
I'lvslmuU-r ((
I'l ll, i:isi-s/k»
i sr. r..\
i-miiu-ri)
i'inilli'(l)
i'inilU'(l)
(lumk;il
l-'niissiiiiis in
llinissiiiiis in
rimissiiiiis iii
1"inissiims in
rim issiims iii
rim issiims iii
( iK-mkiil Viiih-
\:iiik-
l-'lVsllHilUT
Villi nil Soil
l"lVslm;iliT
Villir;il Siiil
l-'rvsliHiiUT
Niilunil Siiil
Lead
Pb(II)
6.9E+2
4.1E+2
1.4E-7
8.5E-8
5.0E-5
3.0E-5
Copper
Cu(II)
9.9E+6
5.2E+6
8.8E-6a
4.5E-6a
1.4E-7
7.2E-8
Zinc
Zn(II)
1.3E+5
7.3E+4
-
-
2.6E-4
1.4E-4
Nickel
Ni(II)
3.0E+5
1.5E+5
1.2E-4
6.1E-5
6.7E-6
3.4E-6
Chromium
Cr(III)
8.1E+3
4.1E+3
-
-
2.1E-11
1.0E-11
Cadmium
Cd(II)
2.3E+6
1.2E+6
1.7E-5
8.9E-6
4.7E-3
2.4E-3
Mercury
Hg(H)
2.2E+4
1.6E+4
1.5E-4
1.1E-4
0.02
0.01
a - Estimated using the median of heavy metals with available characterization factors.
KP-C-16-003; WA 2^37
B-18
-------
Appendix C: Toxic Organics
APPENDIX C
DETAILED CHARACTERIZATION OF TOXIC ORGANICS BEHAVIOR
IN STUDY TREATMENT CONFIGURATIONS
KP-C-16-003; WA 2^37
-------
Appendix C: Toxic Organics
Appendix C: Detailed Characterization of Toxic Organics Behavior in Study
Treatment Configurations
C.l Toxic Organics: Introduction
This section presents background information and methods used to estimate the
environmental impact associated with select trace organic chemical releases in the Level 1
through 5 treatment systems.
Toxic organics are a diverse and growing category of chemical substances that includes
other commonly referred to pollutant groups such as contaminants of emerging concern (CECs),
pharmaceuticals and personal care products (PPCPs), and endocrine disrupting chemicals
(EDCs). The pollutant category includes medications, fragrances, insect repellents and other
household items that can be harmful to environmental and human health at even trace levels
(U.S. EPA 2015c; Montes-Grajales et al. 2017).
Many toxic organics have a documented presence in surface waters, groundwater,
wastewater and WWTP effluent, both in the U.S. and globally (Ellis 2008; Ebele et al. 2017;
Montes-Grajales et al. 2017). No comprehensive list exists, though based on the diverse literature
the number of contaminants is at least in the hundreds (if not thousands) and is continually being
expanded upon as analytical techniques for measuring both presence and toxicity are continually
refined. In order to provide a targeted analysis of their behavior in WWTPs, a restricted group of
43 pollutants (Table C-l) has been selected for specific treatment in this analysis. The selected
pollutant group uses the chemical list from Rahman et al. (2018) as a starting point. Rahman et
al. (2018) performed a comparative LCA that examines the effect of toxic organics removal on
life cycle human health and ecotoxicity impacts for treatment systems that correspond to three
levels of nutrient removal, focusing on the use of advanced tertiary processes for toxic organics
removal. Their selection of toxic organics was based on frequency of presence in WWTPs and
availability of information regarding concentration, chemical degradation, transformation and
removal. Several additional common chemicals, including triclocarban, tonalide, celestolide,
phantolide and musk ketone, were added based on the assessment of Montes-Grajales et al.
(2017), which looked at the presence of PPCPs in global water resources and found these
compounds to be the most widely reported. Per- and Polyfluoroalkyl Substances (PFAS) are not
included in this toxic organics' assessment.
The concentration of trace pollutants can vary considerably on a daily and seasonal basis
and between WWTPs (Martin Ruel et al. 2012). Urban WWTPs have also been shown to receive
higher influent concentrations of some toxic organics that are less common in rural water
systems. As such, the median influent concentrations from Table C-l were used as input to
subsequent calculations as the averages had a tendency to be strongly influenced by a small
number of very high influent concentration records. Figure C-l and Figure C-2 present boxplots
of the influent concentration of toxic organics. The figures divide the pollutants into two
subgroups to allow better visualization across pollutants with considerably different influent
concentrations. Acetaminophen is excluded from these figures due to its notably greater median
influent concentration, 97 |ig/L, as compared to the other included pollutants. The figures show
the tendency for some pollutant distributions to skew towards large outlier values, causing a
disparity between the median and average values.
KP-C-16-003; WA 2^37
C-l
-------
Appendix C: Toxic Organics
Table C-l. Occurrence of the Selected Toxic Organic Compounds in WWTP Influent
( hemic;il \:imo
C hcmicitl Tvpo/l so
1
A\or:i«>o
llllllOIll C'OIH'I
Modi it ii
.Munition (uji/l
Minimum
-)
M ;i \ i in ii in
Siimplo Si/o
accLcuiunuphcn
pain reliever, aiili-
inflammatory
97
19
0.02
400
12
androstendione3
steroid hormone
0.29
0.10
0.02
1.3
7
atenolol
beta blocker
4.3
1.1
0.03
26
10
atorvastatin
lipid regulator
0.49
0.22
0.07
1.6
6
atrazineb
pesticide
0.02
0.02
1.0E-3
0.06
5
benzophenone
PCP, sunscreen
0.24
0.27
7.0E-3
0.42
4
bisphenol A
EDC, plasticizer
4.6
0.84
0.01
44
16
butylated hydroxyanisolec
beta blocker
1.3
0.16
0.13
3.5
3
butylated hydroxytoluene
beta blocker, cosmetic
0.93
0.41
0.05
3.5
5
butylbenzyl phthalated
plasticizer
0.11
0.11
0.08
0.14
2
carbamazepine3
Anti-convulsant
0.92
0.69
0.04
3.8
28
N,N-diethyl-meta-toluamide (DEET)
insect repellent
1.4
0.40
0.02
6.9
6
diclofenac
Analgesics, anti-
inflammatory
2.1
0.96
1.0E-3
17
20
dilantin
anti-seizure medication
0.16
0.17
0.05
0.24
4
dioctyl phthalateb
plasticizer, industry
23
1.4
1.1
67
3
estradiol30
EDC, steroid hormone
0.59
0.03
8.0E-3
5.0
11
estrone30
EDC, steroid hormone
0.17
0.05
0.01
1.0
9
galaxolide
beta blocker, PCP,
fragrance
4.3
2.3
1.4E-3
25
16
gemfibrozil3
lipid regulator
3.1
1.6
0.02
22
15
hydrocodone
analgesic, opioid
0.08
0.11
0.02
0.12
5
ibuprofen3
Analgesics, anti-
inflammatory
7.8
2.4
1.0E-3
39
27
iopromide
contrast agent
7.4
0.05
0.01
38
6
meprobamate
tranquilizer, medication
0.40
0.35
0.01
0.97
5
naproxen3
Analgesics, anti-
inflammatory
8.5
2.5
2.0E-3
53
20
nonylphenolbc
EDC, disinfectant,
surfactant, solvent
3.4
2.3
0.02
9.7
14
KP-C-16-003; WA 2^37
C-2
-------
Appendix C: Toxic Organics
Table C-l. Occurrence of the Selected Toxic Organic Compounds in WWTP Influent
( hemic;il \:imo
(homicnl Tvpo/l so
1
A\or:i«>o
llllllOIll C'OIH'I
Modi it ii
.Munition (uji/l
Minimum
-)
Maximum
Siimplo Si/o
ocl\ 1 phenol
LDC, surfactant, solvent
i.y
U.41
u.i:
8.7
i:
o-hydroxy atorvastatin
lipid regulator
0.12
0.12
0.10
0.14
2
oxybenzone
PCP
1.2
0.39
0.03
3.8
4
p-hydroxy atorvastatin
lipid regulator
0.12
0.12
0.10
0.14
2
progesterone3
EDC
0.02
0.01
3.1E-3
0.06
4
sulfamethoxazole3
antibiotic
1.1
0.43
0.04
4.5
14
tris(2-chloroethyl) phosphate (TCEP)
flame retardant,
plasticizer
0.35
0.24
0.17
0.65
3
tris(2-chloroisopropyl) phosphate
(TCPP)
flame retardant
1.2
1.2
1.1
1.3
2
testosterone3
EDC
0.06
0.05
0.01
0.14
5
triclosan3
pesticide, disinfectant
2.7
0.80
2.3E-3
24
17
trimethoprim3
antibiotic
0.52
0.53
0.10
1.4
8
triclocarban3
disinfectant
0.42
0.42
0.29
0.54
2
tonalide
beta blocker, PCP,
fragrance
1.5
0.80
5.0E-5
7.6
13
celestolide
PCP, fragrance
5.1
0.07
0.04
15
3
phantolide
fragrance
0.10
0.10
0.04
0.15
2
clofibric acid
lipid regulator
0.46
0.29
0.03
1.1
3
musk ketone
fragrance
0.12
0.12
0.10
0.15
3
diuronbc
fragrance
0.14
0.11
0.05
0.25
3
a - Identifies substances with EPA developed analytical methods for detection of contaminants of emerging concern per (U.S. EPA, 2017).
b - Identifies substances with a European Quality Standard per (EP 2008).
c - Identifies substances identified inEPA's Candidate Contaminant List (CCL), version 4 (U.S. EPA, 2016). The CCL identifies chemicals that are currently
unregulated but may pose a risk to drinking water,
d - Identifies substances identified as human health criteria in Section 304(a) of the Clean Water Act (U.S. EPA, 2019c).
Table Acronyms: EDC - endocrine disrupting chemical, PCP - personal care product.
KP-C-16-003; WA 2^37
C-3
-------
Appendix C: Toxic Organics
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Figure C-l. Boxplot of the Influent Concentration of Toxic Organics with Maximum Concentration Less than 4 jig/L.
EP-C-16-003; WA 2-37
C-4
-------
Appendix C: Toxic Organics
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J*
,
-------
Appendix C: Toxic Organics
C.2 Fate of Toxic Organics during Wastewater Treatment
A great deal of work has been done regarding the degradation and partitioning of toxic
organics within municipal WWTPs. The extent of degradation as well as the mechanisms of
removal can vary widely, reflecting the underlying diversity in the pollutants themselves and
conditions and operational procedures practiced at WWTPs. For example, some chemicals such
as acetaminophen and bisphenol A are highly degradable and exhibit excellent removal, often
greater than 90 percent, in conventional (Level 1) treatment works (Liwarska-Bizukojc et al.
2018). Conversely, chemicals such as diclofenac and trimethoprim are more recalcitrant,
exhibiting removal efficiencies of less than 80 percent in conventional treatment systems
(Ahmed et al. 2017, Ogunlaja et al. 2013). The term removal efficiency is used to refer to the
combined effect of biodegradation and partitioning to solids, unless otherwise specified.
As a general rule-of-thumb, Level 1 treatment systems remove approximately 80 percent
of the toxic organic load from the liquid stream (Martin Ruel et al. 2012). Removal that is
attributable to solids partitioning versus biodegradation varies according to pollutant. The reason
for this variation is not well agreed upon within the literature. Martin Ruel et al. (2012) states
that roughly two-thirds of pollutant removal can be accounted for by partitioning to sludge, while
Jelic et al. (2011) found that this pathway was considerably less important. Biodegradation is a
second important removal pathway, especially for chemicals that remain dissolved in the liquid
fraction of wastewater. Volatilization of organic pollutants is expected to contribute negligibly to
removal of most pollutants. Of the reviewed pollutants only celestolide is known to count
volatilization as a significant loss pathway, accounting for up to 16% of total pollutant removal
(Luo et al. 2014). Generally, volatilization is only expected to be relevant for treatment systems
that have a large surface area (Liwarska-Bizukojc et al. 2018), which is not the case for any of
the studied treatment configurations.
Several chemical properties of trace organics including the octanol-water coefficient
(K OW ) and acid dissociation constant (pKa) affect the partitioning of individual organic pollutants
between the solid and liquid phase in a WWTP (Alvarino et al. 2018). Pollutants with a high log
Kow should preferentially adsorb to the solid fraction of wastewater (Alvarino et al. 2018). Luo et
al. (2014) identified a log Kow threshold of 4, above which pollutants have a high sorption
potential. Trace pollutants with a log Kow of less than 2.5 (hydrophilic) have a low sorption
potential and will tend to remain in the dissolved phase. For example, many pesticides have a log
Kow of less than three, are hydrophilic and predominantly exist in the dissolved phase (Martin
Ruel et al. 2012). The solid-water distribution coefficient (Kd) is defined as the ratio between the
concentration in the liquid and solid phases of a solution under equilibrium conditions and has
been used to determine the fraction of trace pollutants that partition to sludge (Alvarino et al.
2018). For pollutants with a log Kd value of less than 2.5, sorption onto sludge can be considered
negligible (Luo et al. 2014). Other authors indicate that Kow alone does not provide a consistent
indicator of removal performance (Oppenheimer et al. 2007), indicating that generalized
approaches should be used with caution and interpreted appropriately. For example, Alvarino et
al. (2018) state that hormones with high Kow will tend to partition to sludge, however Martin
Ruel et al. (2012) found that the majority of hormones are generally found in the dissolved
phase, highlighting the complexity of these interactions.
EP-C-I6-QQ3; WA 2^37
C-6
-------
Appendix C: Toxic Organics
Within the literature, there are three unit-process parameters most commonly found to
affect pollutant degradation rates: (1) solids retention time (SRT), (2) hydraulic retention time
(HRT), and (3) redox condition. Biomass conformation (i.e., size and type), use of adsorbents,
pH, and temperature are additional unit process parameters that may vary between treatment
configurations and affect pollutant degradation or removal (Alvarino et al. 2018). The pH of
wastewater can affect removal of some micropollutants, particularly acidic pharmaceuticals for
which the affinity to biosolids was pH affected (Luo et al. 2014). These additional factors were
excluded from the current study as they are not expected to vary considerably between the nine
treatment configurations, or are unknown, as in the case of biomass conformation.
Solids retention time is a measure of sludge age in secondary biological treatment
processes. Longer SRT, in general, allows the growth and proliferation of slower growing
microbial partners, and is thought to increase the diversity of organisms present in mixed liquor
suspended solids (Luo et al. 2014). Biodegradation of organic pollutants has been shown to
exhibit a variable dependence on SRT according to specific chemical characteristics.
Oppenheimer et al. (2007) calculated the minimum SRT value required for 80 percent CEC
removal (SRT80) for several common CECs. Easily degradable compounds such as ibuprofen
and oxybenzone had an SRT80 of less than 5 days, while poorly degradable substances such as
galaxolide had SRT80 values of greater than 15 days. Results showed a pronounced plateau in
removal performance for SRTs greater than the SRT80 value for each respective chemical.
Hydraulic retention time measures the average period that water is retained in a given
treatment unit. Longer HRT allows more time for biodegradation and partitioning to solids. HRT
often correlates with SRT and it can therefore be difficult to determine the predominant factor
contributing to variations in pollutant removal. The literature shows variable pollutant removal
responses to HRT, which in some cases can be marginal (Oppenheimer et al. 2007).
Redox conditions are defined as the tendency of a given redox reaction to occur. In
wastewater treatment, redox conditions are categorized into the three broad conditions of
aerobic, anoxic, and anaerobic. Aerobic is the presence of free oxygen and indicates positive
redox values. Anoxic indicates the presence of bound oxygen (e.g., nitrate) and redox values
around zero. Negative redox conditions indicate the absence of free and/or bound oxygen. Redox
values are indicators of what types of microbial communities may be active and which chemical
reactions may occur in a given wastewater. Research has shown that the removal rate of specific
organic pollutants varies according to the redox environment. Overall, aerobic conditions have
been shown to more effectively degrade the broadest range of substances. Anaerobic
environments had greater removal performance for a small number of compounds, some of
which were not degraded in aerobic environments (Alvarino et al. 2018). Anoxic conditions were
in many cases found to be a less effective environment for removal of toxic organics, however
some chemicals such as diclofenac, clofibric acid, and contrast agents exhibited improved
removal under anoxic conditions (Luo et al. 2014). It is suspected that anoxic conditions often
found in advanced biological treatment systems, intended for nitrogen removal, are not
particularly effective in the degradation of organic micropollutants (Alvarino et al. 2018). The
effect of variable redox conditions, such as those present in the level 2 through 5 treatment
systems assessed in this study, on toxic organics removal are still understudied (Alvarino et al.
2018).
KP-C-16-003; WA 2^37
C-7
-------
Appendix C: Toxic Organics
The preceding unit process and chemical characteristics are some of the primary
determinants of the fate of toxic organics within wastewater treatment systems. Those chemicals
that partition readily to solids will tend to settle out with the sludge, be subject to anaerobic
digestion and exit the plant heading to landfills or land application. Un-degraded dissolved
chemicals will exit with the WWTP effluent and enter receiving surface waters.
C.3 Toxic Organics Removal Performance Estimation Methodology
This section describes the data and methods used to quantify a range of estimated
removal efficiencies for individual unit processes that compose the 9 WWTP configurations of
this study and to combine unit level removal efficiency data to estimate cumulative removal
efficiency for each of the 9 WWTP configurations. Low, medium and high estimates of removal
efficiency were developed for each unit process and are used to define corresponding estimates
of cumulative removal efficiency for each configuration. Limited data were found to define
chemical specific removal efficiencies for the advanced biological treatment units of Levels 2
through 5. Therefore, sensitivity approaches were used to assess the importance of
biodegradation and solids partitioning in advanced biological treatment units to the overall
environmental impact of each respective system described below.
C.3.1 Biological Treatment
Biological treatment processes contribute to both the degradation of toxic organic
compounds and additional partitioning to solids by creating biological flocculants that provide
adsorption sites and allow time for metabolic degradation and adsorption to take place. Owing to
these processes, Miege et al. (2009) note that removal of toxic organics from the liquid portion of
biological wastewater treatment is typically in the range of 50-90%, and that nitrogen removal
improves the removal efficiency of many pharmaceutical compounds. Additionally, the work of
Alvarino et al. (2018) concludes that hybrid biological reactors offer a "good alternative to
enhance the removal of organic micropollutants." This is expected to be especially true for
pollutants that are not readily degraded in aerobic conditions such as sulfamethoxazole and
trimethoprim.
Table C-2 presents a summary of the Level 1, activated sludge removal efficiency of the
toxic organics considered in this study. To facilitate discussion of diverse and sometimes
divergent treatment performances, this study adopts a classification system for biological
treatment systems developed by Oppenheimer et al. (2007) that characterizes overall treatment
performance as "good", "moderate" or "low". Good removal efficiency is defined as 80% or
greater. Moderate removal efficiency is classified as being in the range of 50-80% removal,
while less than 50% removal efficiency is considered poor.
Based on Table C-2, Level 1 treatment systems promote "Good" removal efficiency of at
least 30%) of the toxic organics examined. The table also includes low, medium and high
estimates of removal efficiency for the Level 1 treatment system, which includes the combined
effect of primary and secondary treatment processes. Removal efficiency includes both
biodegradation and the fraction of toxic organics that partition to solids and are removed in
primary and waste activated sludge. Low, medium and high estimates in the table were defined
as the 25th percentile, median and 75th percentile of the documented removal efficiencies. In
KP-C-16-003; WA 2^37
C-8
-------
Appendix C: Toxic Organics
instances where removal efficiencies are negative (i.e. formation), a value of zero has been
substituted for use in this study (e.g. carbamazepine).
No removal efficiency data were found for eight of the 43 chemicals including: butylated
hydroxyanisole, butylated hydroxytoluene, dilantin, hydrocodone, o-hydroxy atorvastatin, p-
hydroxy atorvastatin, TCPP and triclocarban (marked with italics in Table C-2). Proxy values
that bracket the extreme values for removal efficiency were used to determine if the removal of
these chemicals is significant in the LCA results. Proxy removal efficiency values of 0%, 50%,
and 100% were applied in the low, medium and high removal efficiency scenarios, respectively.
The selection of 0% and 100% in the low and high removal efficiency scenarios was based on
the minimum and maximum removal across the 35 pollutants with reported level 1 removal
efficiency data. The removal efficiency estimate in the medium removal efficiency scenario is
halfway between the minimum and maximum values.
Preliminary screening and grit removal were assumed to have no effect on partitioning
and degradation of toxic organics. Reported removal performance of biological treatment units
was assumed to include operation of the secondary clarifier, which is not assessed separately. It
is important to note that within the literature it is often not clear whether pollutant removal is the
result of solids partitioning or biodegradation.
Studies have shown that expected changes in toxic organic influent concentrations do not
produce a noticeable effect on removal efficiency (Oppenheimer et al. 2007). One study looking
at estradiol, diclofenac, and nonylphenol showed indistinguishable removal rates at influent
concentrations of 1 and 10 |ig/L (Liwarska-Bizukojc et al. 2018). Based on this observation, we
utilized all available removal data for a given unit process, regardless of reported influent
concentration.
Table C-2. Degradation and Removal of Toxic Organics within the Level 1 Biological
Treatment System
C'heiniciil \:imc
kcmoMil - C 'hiss'1
Rem
Low
)\jiI KITicicni
Medium
V - I.OM'I 1
1 liuli
acetaminophen
Good
92%
luu%
luu%
androstendione
Good
96%
98%
99%
atenolol
Medium
30%
70%
81%
atorvastatin
Good
88%
90%
92%
atrazine
Poor
26%
28%
29%
benzophenone
Good
79%
80%
80%
bisphenol A
Good
77%
85%
98%
butylated hydroxyanisole *
N/A
0%
50%
100%
butylated hydroxytoluene *
N/A
0%
50%
100%
butylbenzyl phthalate
Good
80%
80%
80%
carbamazepine
Poor
0%
0%
22%
N,N-diethyl-meta-toluamide
(DEET)
Medium
50%
50%
50%
diclofenac
Poor
22%
49%
68%
KP-C-16-003; WA 2^37
C-9
-------
Appendix C: Toxic Organics
Table C-2. Degradation and Removal of Toxic Organics within the Level 1 Biological
Treatment System
( heiniciil Nitmc
Rcmoxnl - (l:iss;i
Rem
Low
)\:il Kliiciciu
Medium
V - I.OM'I 1
Miiili
dilantin*
N/A
0%
50%
100%
dioctyl phthalate
Medium
70%
70%
70%
estradiol
Good
73%
96%
98%
estrone
Good
14%
81%
95%
galaxolide
Medium
47%
77%
87%
gemfibrozil
Medium
67%
70%
75%
hydrocodone*
N/A
0%
50%
100%
ibuprofen
Good
80%
96%
99%
iopromide
Poor
0%
0%
8%
meprobamate
Poor
0%
0%
0%
naproxen
Medium
56%
73%
94%
nonylphenol
Medium
62%
78%
89%
octylphenol
Good
63%
80%
95%
o-hydroxy atorvastatin *
N/A
0%
50%
100%
oxybenzone
Good
72%
80%
89%
p-hydroxy atorvastatin *
N/A
0%
50%
100%
progesterone
Good
92%
93%
95%
sulfamethoxazole
Poor
31%
50%
66%
tris(2-chloroethyl)phosphate
(TCEP)
Medium
50%
50%
50%
tris(2-chloroisopropyl)
phosphate (TCPP)*
N/A
0%
50%
100%
testosterone
Good
86%
90%
95%
triclosan
Medium
58%
71%
76%
trimethoprim
Poor
18%
20%
29%
triclocarban *
N/A
0%
50%
100%
tonalide
Good
61%
84%
86%
celestolide
Medium
0%
60%
68%
phantolide
Poor
0%
9%
34%
clofibric acid
Medium
50%
52%
53%
musk ketone
Poor
0%
25%
38%
diuron
Poor
30%
30%
30%
a - Removal class refers to the qualitative removal efficiency classification thresholds defined by (Oppenheimer et
al. 2007). Poor = <50% removal, Medium = 50-80% removal, Good = >80% removal. Classifications were
assigned based on the median removal efficiency.
* Marked and italicized chemicals lack data on removal efficiency and use 0%, 50%, and 100% as proxy removal
efficiency values to determine significance in LCA results.
KP-C-16-003; WA 2^37
C-10
-------
Appendix C: Toxic Organics
C.3.2 Advanced Biological Treatment
The majority of literature related to degradation and removal of toxic organics considers
the removal efficiency of entire WWTPs or advanced tertiary processes (e.g. RO, ozonation).
Because of this limitation it was not possible to determine individualized removal efficiencies
that correspond to each of the advanced biological treatment units. Therefore, a more generalized
approach was used to define low, medium and high estimates of removal efficiency for advanced
biological treatment works.
As a conservative estimate, the low removal efficiency of the advanced treatment systems
was set equal to the low removal efficiency of the Level 1 treatment system, which was based on
the 25th percentile of documented values. The medium removal efficiency scenario value for
Levels 2 through 5 was established assuming an increase in removal performance that is 25%
(EFinc.y) beyond the Level 1 median removal efficiency. The high removal efficiency scenario
value assumes a removal performance that is 50% (EFinc.y) above the Level 1 median removal
efficiency as calculated in Equation C-l. For example, assuming a median removal efficiency for
Level 1 treatment of 50%, the removal efficiency of advanced biological treatment units would
be 62.5%) and 75%> (EFX) in the medium and high removal efficiency scenarios. The proposed
increases in removal efficiency attributed to Levels 2 through 5 are indicative of increased HRT,
SRT and variable redox conditions that are known to increase removal efficiency of many toxic
organics as discussed in Section C.2 and document in the removal notes of Table C-3.
EFX = EFmed + [(1 - EFmed) X EFinc y]
Equation C-l
Where:
EFX = Adjusted removal efficiency of scenario x
EFmed = Level 1 median removal efficiency
EFinc.y = Removal efficiency increase factor y (varies by scenario)
Table C-3 summarizes the calculated advanced biological process removal efficiency
values for individual organic pollutants used in the sensitivity analysis. The notes in Table C-3
describe additional information that sheds light on how the studied compounds may respond to
alternate redox conditions and longer HRTs and SRTs that characterize the advanced biological
treatment units of Levels 2 through 5. As noted above, several authors state that current evidence
indicates that comparable or improved removal efficiencies can be expected in advanced
biological treatment works. Examination of removal notes in Table C-3 often confirms this
perspective, however, there are also numerous instances where the findings of authors contradict
one another. For example, Lakshminarasimman et al. (2018) identified improved removal of
bisphenol A at high SRTs, whereas (Luo et al. 2014) identified no significant effect of SRT on
removal efficiency. What is clear from Table C-2 and Table C-3 is the conclusion that individual
toxic organics respond differently to the range of conditions that characterize both activated
sludge and advance nutrient removal WWTPs. The sensitivity approach described in this section
will allow the analysis to judge the importance of removal efficiency estimates on final LCA
results.
EP-C-I6-QQ3; WA 2^37
C-ll
-------
Appendix C: Toxic Organics
Table C-3. Toxic Organic Removal Efficiency of Advanced Biological Treatment Process
I.OM'I 1
keimn ill KITiciencv
Ad\ itneed
(hemiciil Nitme
lii()lo»ic;tl Processes (l.e\els 2-5)
Mcdiitn
Low
Medium
1 li»h
kemoMil Notes
acetaminophen
100%
92%
100%
100%
androstendione
98%
96%
98%
99%
atenolol
70%
30%
78%
90%
Biodegrades in all three redox conditions. Degradation
was greatest under aerobic conditions
(Lakshminarasimman et al. 2018)
Better removal at high SRT (Lakshminarasimman et al.
2018)
Less than 20% removal under aerobic conditions
(Miege et al. 2009)
Poor to moderate removal in activated sludge, 45-80%
(Martin Ruel et al. 2012)
atorvastatin
90%
88%
93%
96%
atrazine
28%
26%
46%
64%
benzophenone
80%
79%
85%
90%
bisphenol A
85%
77%
89%
99%
Biotransformation is catalyzed by nitrifying conditions
(Lakshminarasimman et al. 2018)
Not affected by SRT (Luo et al. 2014)
Better removal at high SRT (Lakshminarasimman et al.
2018)
butylated hydroxyanisole *
50%
0%
63%
100%
butylated hydroxytoluene *
50%
0%
63%
100%
butylbenzyl phthalate
80%
80%
85%
90%
carbamazepine
0%
0%
25%
61%
Poor removal (Miege et al. 2009; Martin Ruel et al.
2012)
Removal less than 20% under all redox conditions
(Alvarino et al. 2018; Lakshminarasimman et al. 2018)
Removal less than 25% under aerobic conditions (Jelic,
(Miege et al. 2009; Jelic et al. 2011)
N,N-diethyl-meta-toluamide
(DEET)
50%
50%
63%
75%
Degradation is primarily aerobic (Lakshminarasimman
et al. 2018)
Poor removal in anaerobic conditions
KP-C-16-003; WA 2^37
C-12
-------
Appendix C: Toxic Organics
Table C-3. Toxic Organic Removal Efficiency of Advanced Biological Treatment Process
(hemiciil Nitme
I.OM'I 1
Mcdiitn
keimn;
|}i(>lo«ic
Low
1 KITiciencv
ill Processes
Medium
Ad\ itneed
l.e\els 2-5)
1 li»h
kemoMil Notes
(Lakshminarasimman et al. 2018)
Better removal at high SRT
(Lakshminarasimman et al. 2018)
diclofenac
49%
22%
62%
84%
Removal <20% under all redox conditions (Alvarino et
al. 2018)
Anoxic conditions have a positive influence on removal
(Luo et al. 2014)
Exhibited inconsistent overall removal. (Jelic et al.
2011)
Poor to moderate removal in activated sludge, less than
60% (Miege et al. 2009)
Poor removal in activated sludge, <50% (Martin Ruel
et al. 2012)
dilantin*
50%
0%
63%
100%
dioctyl phthalate
70%
70%
78%
85%
Poor to moderate removal in all three redox conditions
(Luo et al. 2014)
High HRT increases removal to sludge (Luo et al.
2014)
estradiol
96%
73%
97%
99%
Biotransformation is catalyzed by nitrifying conditions
(Lakshminarasimman et al. 2018)
Better removal at high SRT (Lakshminarasimman et al.
2018)
Moderate to good removal in activated sludge, 65-
100% (Miege et al. 2009)
Good degradation in aerobic conditions (Alvarino et al.
2018)
Moderate degradation in anaerobic conditions
(Alvarino et al. 2018)
KP-C-16-003; WA 2^37
C-13
-------
Appendix C: Toxic Organics
Table C-3. Toxic Organic Removal Efficiency of Advanced Biological Treatment Process
Chemiciil Nitme
I.C\cl 1
Mciliiin
keimn;
|}i(>lo«ic
Low
1 KITiciencv
ill Processes
Medium
Ail\ ;i n ceil
l.e\els 2-5)
1 li»h
kemoMil Notes
estrone
81%
14%
85%
98%
Biotransformation is catalyzed by nitrifying conditions
(Lakshminarasimman et al. 2018)
Better removal at high SRT (Lakshminarasimman et al.
2018)
Moderate to good removal in activated sludge, 45-
100% (Miege et al. 2009)
Good degradation in aerobic conditions (Alvarino et al.
2018)
Moderate degradation in anaerobic conditions
(Alvarino et al. 2018)
galaxolide
77%
47%
83%
93%
Poor degradation (Oppenheimer et al. 2007)
Good aerobic degradation (Alvarino et al. 2018)
Moderate anoxic degradation (Alvarino et al. 2018)
Poor anaerobic degradation (Alvarino et al. 2018)
Poor to moderate removal in activated sludge, 25-75%
(Miege et al. 2009)
gemfibrozil
70%
67%
78%
87%
Moderate removal in activated sludge (Miege et al.
2009)
hydrocodone*
50%
0%
63%
100%
ibuprofen
96%
80%
97%
100%
Good degradation (Oppenheimer et al. 2007)
Good aerobic degradation (Alvarino et al. 2018)
Poor anaerobic and anoxic degradation (Alvarino et al.
2018)
Biotransformation is catalyzed by nitrifying conditions
(Lakshminarasimman et al. 2018)
Better removal at high SRT (Lakshminarasimman et al.
2018)
Moderate to good removal in activated sludge, 50-
100% (Miege et al. 2009)
KP-C-16-003; WA 2^37
C-14
-------
Appendix C: Toxic Organics
Table C-3. Toxic Organic Removal Efficiency of Advanced Biological Treatment Process
l.e\el 1
keimn ill KITiciencv
Ad\ itneed
(hemiciil Nitme
lii()lo»ic;tl Processes (l.e\els 2-5)
Mcdiitn
Low
Medium
1 li»h
kemoMil Notes
iopromide
0%
0%
25%
54%
Anoxic conditions have a positive influence on removal
(Luo et al. 2014)
Biotransformation is catalyzed by nitrifying conditions
(Lakshminarasimman et al. 2018)
Demonstrated no removal in activated sludge (Miege et
al. 2009)
meprobamate
0%
0%
25%
50%
naproxen
73%
56%
79%
97%
Good degradation in aerobic and anaerobic conditions
(Alvarino et al. 2018)
Poor degradation in anoxic conditions (Alvarino et al.
2018)
Biotransformation is catalyzed by nitrifying conditions
(Lakshminarasimman et al. 2018)
Better removal at high SRT (Lakshminarasimman et al.
2018)
Good degradation. Does not accumulate in sludge (Jelic
et al. 2011)
Moderate to good removal in activated sludge, 65-95%
(Miege et al. 2009)
nonylphenol
78%
62%
83%
94%
SRT greater than 20 hours improves removal (Luo et
al. 2014)
octylphenol
80%
63%
85%
98%
o-hydroxy atorvastatin *
50%
0%
63%
100%
oxybenzone
80%
72%
85%
95%
Good degradation (Oppenheimer et al. 2007)
p-hydroxy atorvastatin *
50%
0%
63%
100%
progesterone
93%
92%
95%
97%
KP-C-16-003; WA 2^37
C-15
-------
Appendix C: Toxic Organics
Table C-3. Toxic Organic Removal Efficiency of Advanced Biological Treatment Process
(hemiciil Nitme
l.e\el 1
Medi;m
keimn;
Biologic
Low
1 KITiciencv
ill Processes
Medium
Ad\ ;tnced
l.e\els 2-5)
1 li»h
kemoMil Notes
sulfamethoxazole
50%
31%
62%
83%
Good degradation in anaerobic conditions (Alvarino et
al. 2018)
Poor degradation in anoxic and aerobic conditions
(Alvarino et al. 2018)
Comparable degradation under varying redox
conditions (Lakshminarasimman et al. 2018)
Mixed results on the effect of SRT
(Lakshminarasimman et al. 2018)
Poor to good removal in activated sludge, 35-80%
(Miege et al. 2009)
tris(2-chloroethyl)phosphate
(TCEP)
50%
50%
63%
75%
tris (2-chlorisopropyl) phosphate
(TCPP) *
50%
0%
63%
100%
testosterone
90%
86%
93%
97%
triclosan
71%
58%
78%
88%
Better degradation under aerobic conditions
(Lakshminarasimman et al. 2018)
SRT greater than 20 hours improves removal (Luo et
al. 2014)
Removal rates do not vary with increasing SRT
(Lakshminarasimman et al. 2018)
trimethoprim
20%
18%
40%
65%
Good degradation anaerobic conditions (Alvarino et al.
2018)
Poor degradation under aerobic and anoxic conditions
(Alvarino et al. 2018)
Poor degradation under aerobic conditions, <40%
(Miege et al. 2009)
Demonstrated degradation under anaerobic and anoxic
conditions (Lakshminarasimman et al. 2018)
Mixed results on the effect of SRT
(Lakshminarasimman et al. 2018)
KP-C-16-003; WA 2^37
C-16
-------
Appendix C: Toxic Organics
Table C-3. Toxic Organic Removal Efficiency of Advanced Biological Treatment Process
(hemiciil Nitme
l.e\el 1
Mcdiitn
keimn;
Biologic
Low
1 KITiciencv
ill Processes
Medium
Ail\ ;tnced
l.e\els 2-5)
1 li»h
kemoMil Notes
No significant removal under aerobic conditions (Jelic
et al. 2011)
triclocarban *
50%
0%
63%
100%
tonalide
84%
61%
88%
93%
Good degradation under aerobic conditions (Alvarino
et al. 2018)
Moderate degradation under anaerobic and anoxic
conditions (Alvarino et al. 2018)
Poor to good degradation in activated sludge, 35-85%
(Miege et al. 2009)
celestolide
60%
0%
70%
84%
Good degradation under aerobic conditions (Alvarino
et al. 2018)
Moderate degradation under anaerobic and anoxic
conditions (Alvarino et al. 2018)
Poor to moderate removal in activated sludge, less than
60% (Miege et al. 2009)
Volatilization is a significant loss pathway,
approximately 16% (Luo et al. 2014)
phantolide
9%
0%
32%
67%
clofibric acid
52%
50%
64%
76%
Anoxic conditions have a positive influence on removal
(Luo et al. 2014)
Poor removal in activated sludge, less than 50% (Miege
et al. 2009)
musk ketone
25%
0%
44%
69%
Poor degradation under aerobic conditions (Miege et al.
2009)
diuron
30%
30%
48%
65%
Poor degradation in activated sludge (Martin Ruel et al.
2012)
* Marked and italicized chemicals lack data on removal efficiency and use 0%, 50%, and 100% as proxy removal efficiency values to determine significance in
LCA results.
KP-C-16-003; WA 2^37
C-17
-------
Appendix C: Toxic Organics
It was also necessary to estimate the fraction of pollutant removal that is attributable to
solids partitioning as opposed to biological degradation. Miege et al. (2009) performed an in-
depth review of studies looking at the fate of PPCPs in WWTPs and noted that the vast majority
(87%) of studies focus on the aqueous phase. None of the reviewed studies looked at both
aqueous and solid phases of PPCPs simultaneously. As noted earlier, (Martin Ruel et al. 2012)
proposed that up to two-thirds of pollutant removal can be attributed to solids partitioning. Other
authors disagree with this conclusion, proposing that the majority of removal efficiency is due to
biodegradation (Liu et al. 2009). It is beyond the scope of this analysis to attempt to resolve this
discrepancy.
In the low efficiency scenario, it was assumed that two-thirds of removal efficiency is
due to solids partitioning (one-third biodegradation). The analysis does not specify if this
removal occurs during primary or secondary clarification. The medium removal efficiency
estimates assume a 50-50 split between solids partitioning and biodegradation, while the high
removal efficiency estimates assume that one-third of removal is attributable to solids
partitioning (two-thirds biodegradation). All assumptions related to solids partitioning were
applied to the corresponding removal efficiency as documented in Table C-2.
C.3.3 Anaerobic Digestion
All 9 treatment systems include anaerobic digestion as a sludge processing step, and a
low, medium and high estimate of removal efficiency was established for each of the 43
pollutants using the 25th percentile, median and 75th percentile degradation values. The reviewed
research on anaerobic digestion deals more consistently with pollutants in both the liquid and
solid phase. Removal efficiency measurements for anaerobic digestion tend to refer to
biodegradation explicitly. Pollutant specific data were identified for 20 of the 43 pollutants and
are summarized in Table C-4. Removal efficiency was set as zero for pollutants reporting
negative values. Proxy values that bracket the extreme values for removal efficiency were used
to determine if the removal of the 23 remaining chemicals is significant in the LCA results.
Proxy removal efficiency values of 0%, 50%, and 100% were applied in the low, medium and
high removal efficiency scenarios, respectively. The selection of 0% and 100% in the low and
high removal efficiency scenarios was based on the minimum and maximum removal across the
20 pollutants with reported AD removal efficiency data. The removal efficiency estimate in the
medium removal efficiency scenario is halfway between the minimum and maximum values.
A study by Malmborg and Magner (2015) looked at several sludge treatment steps
including pasteurization, thermal hydrolysis, advanced oxidation and ammonia treatment,
concluding that anaerobic digestion was the most effective at removing organic substances.
Toxic organics pollutants not degraded in anaerobic digestion remain with the solids for disposal
in landfills.
Table C-4. Toxic Organic Removal Efficiency of Anaerobic Digestion
( hemic;il Nitmc
Low
kcimn :t
Medium
Kfl'icicnc)
1 liii'i
(%)
Ritujic (niin-niii\)
acetaminophen
89%
89%
96%
85-100
androstendione *
0%
50%
100%
N/A
atenolol
61%
77%
89%
39-96
EP-C-I6-QQ3; WA 2^37
C-18
-------
Appendix C: Toxic Organics
Table C-4. Toxic Organic Removal Efficiency of Anaerobic Digestion
( hemic;il Nitmc
Low
Rciiiox ;i
Medium
KITicicnc\
Miiili
(%)
(mill-ill;i\)
atorvastatin*
0%
50%
100%
N/A
atrazine *
0%
50%
100%
N/A
benzophenone*
0%
50%
100%
N/A
bisphenol A
12%
30%
84%
0-100
butylated hydroxyanisole *
0%
50%
100%
N/A
butylated hydroxytoluene *
0%
50%
100%
N/A
butylbenzyl phthalate
93%
93%
93%
93-93
carbamazepine
0%
0%
7%
0-15
N,N-diethyl-meta-toluamide (DEET)
0%
0%
0%
0-0
diclofenac
21%
34%
55%
0-78
dilantin*
0%
50%
100%
N/A
dioctyl phthalate *
0%
50%
100%
N/A
estradiol
85%
93%
96%
75-100
estrone
75%
79%
85%
70-95
galaxolide
58%
65%
73%
50-80
gemfibrozil
0%
0%
0%
0-0
hydrocodone*
0%
50%
100%
N/A
ibuprofen
21%
27%
44%
0-70
iopromide
16%
23%
31%
8-38
meprobamate *
0%
50%
100%
N/A
naproxen
86%
89%
93%
76-96
nonylphenol
43%
86%
100%
0-100
octylphenol*
0%
50%
100%
N/A
o-hydroxy atorvastatin *
0%
50%
100%
N/A
oxybenzone*
0%
50%
100%
N/A
p-hydroxy atorvastatin *
0%
50%
100%
N/A
progesterone *
0%
50%
100%
N/A
sulfamethoxazole
79%
99%
100%
23-100
tris(2-chloroethyl)phosphate (TCEP) *
0%
50%
100%
N/A
tris(2-chloroisopropyl) phosphate (TCPP)*
0%
50%
100%
N/A
testosterone *
0%
50%
100%
N/A
triclosan
45%
53%
55%
30-55
trimethoprim
90%
96%
99%
80-100
triclocarban
20%
40%
53%
0-65
tonalide
59%
65%
67%
52-68
celestolide *
0%
50%
100%
N/A
phantolide *
0%
50%
100%
N/A
clofibric acid*
0%
50%
100%
N/A
musk ketone *
0%
50%
100%
N/A
diuron *
0%
50%
100%
N/A
* Marked and italicized chemicals lack data on removal efficiency and use 0%, 50%, and 100% as proxy removal
efficiency values to determine significance in LCA results.
KP-C-16-003; WA 2^37
C-19
-------
Appendix C: Toxic Organics
C. 3.4 Chemical Phosphorus Removal
The effect of chemical phosphorus removal was considered to the extent that it is
expected to enhance partitioning and settling of toxic organics. Alexander et al. (2012) reviewed
the available literature on the effect of chemical coagulation on trace organic pollutant removal.
They found that chemical phosphorus removal (i.e. chemical coagulation) has been demonstrated
to be an inefficient means of removing trace organics from the liquid phase of wastewater.
Across different categories of organic chemicals, average removal efficiency of chemical
coagulation varies between six and 77%.
Table C-5 lists low, medium and high removal efficiency scenario values used in this
study. Pollutant specific data was identified for 9 of the 43 toxic organic compounds. Twenty-
eight of the 43 chemicals were assigned removal efficiency data based on their assigned
chemical class, as listed in Table C-5. No data was identified for 15 of the toxic organic
chemicals, and they were assigned the median removal efficiency across all chemical classes of
34% (Alexander et al. 2012).
Six of the nine treatment systems included in this study utilize chemically enhanced
secondary clarification. The low removal efficiency scenario assumes no increase in removal
efficiency relative to secondary clarification without a preceding alum addition. The medium and
high removal efficiency scenarios assume that 50% and 100% of the identified chemical
coagulation removal efficiencies are in addition to the removal realized by the combined
biological process and secondary clarification (without alum addition). The range of these
assumptions is wide to accommodate the fact that Alexander et al. (2012) presents chemical
coagulation as a stand-alone unit process. The precise relationship between the removal
efficiency of stand-alone chemical coagulation and chemically enhanced secondary clarification
is not known.
Table C-5. Toxic Organic Removal Efficiency of Chemical Coagulation
Romo\ ill KITicicncv - C'heiniciil
C'lioiniciil Nninc
( hemicitl C'Ijiss'1
Coit^uhtlion1'
Low
Medium
Miuli
acetaminophen3
N/A
-
24%
48%
androstendione
hormone
-
9.5%
19%
atenolol3
beta-blocker
-
9.5%
19%
atorvastatin
hypolipidemic agent
-
13%
26%
atrazine
pesticide
-
15%
30%
benzophenone*
N/A
-
17%
34%
bisphenol A *
N/A
-
17%
34%
butylated hydroxyanisole
beta-blocker
-
17%
34%
butylated hydroxytoluene
beta-blocker
-
17%
34%
butylbenzyl phthalate
phthalate
-
25%
49%
carbamazepinec
N/A
-
15%
30%
N,N-diethyl-meta-toluamide (DEET)
pesticide
-
15%
30%
diclofenac0
anti-inflammatory
-
25%
50.0%
dilantin*
N/A
-
17%
34%
dioctyl phthalate
phthalate
-
25%
49%
estradiol0
hormone
-
1.0%
2.0%
KP-C-16-003; WA 2^37
C-20
-------
Appendix C: Toxic Organics
Table C-5. Toxic Organic Removal Efficiency of Chemical Coagulation
Romo\ill KITicicncv - C hcmicitl
Chcmicitl Nitme
( hemic;il ("hiss"'
(oii^uliilion1'
Low
Medium
lli»h
estrone0
hormone
-
6.0%
12%
galaxolide
beta-blocker
-
39%
77%
gemfibrozil
musk fragrance
-
13%
26%
hydrocodonec
N/A
-
12%
24%
ibuprofen
anti-inflammatory
-
18%
35%
iopromide *
N/A
-
17%
34%
meprobamate *
N/A
-
17%
34%
naproxen0
anti-inflammatory
-
11%
23%
nonylphenol*
N/A
-
17%
34%
octylphenol*
N/A
-
17%
34%
o-hydroxy atorvastatin
hypolipidemic agent
-
13%
26%
oxybenzone*
N/A
-
17%
34%
p-hydroxy atorvastatin
hypolipidemic agent
-
13%
26%
progesterone0
hormone
-
6.3%
13%
sulfamethoxazole
antibiotic
-
20%
39%
tris(2-chloroethyl)phosphate (TCEP) *
N/A
-
17%
34%
tris(2-chloroisopropyl) phosphate
(TCPP) *
N/A
-
17%
34%
testosterone
hormone
-
9.5%
19%
triclosan
pesticide
-
15%
30%
trimethoprim
antibiotic
-
20%
39%
triclocarban *
N/A
-
17%
34%
tonalide
musk fragrance
-
28%
56%
celestolide
musk fragrance
-
39%
77%
phantolide
musk fragrance
-
39%
77%
clofibric acid
hypolipidemic agent
-
13%
26%
musk ketone
musk fragrance
-
39%
77%
diuron *
N/A
-
17%
34%
a - Chemical classes are based on trace organic compound classes defined in Table 4 of (Alexander et al. 2012).
b - Removal efficiency of chemical coagulation is in addition to the removal efficiencies for combined biological
treatment and secondary clarification listed in Table 1-3 and Table 1-4.
c - Chemical specific removal efficiency data was drawn from (Alexander et al. 2012).
* Marked values use median removal efficiency of all chemical classes defined in Alexander et al. ( 2012) as the
proxy removal efficiency value.
C. 3.5 Membrane Filtration
For the fraction of toxic organics that remain in the dissolved phase there are subsequent
unit processes to consider following biological treatment. Media filters and ultrafiltration
membranes do not physically screen toxic organic compounds as the molecules are often two
orders of magnitude smaller than the membrane pores (Oppenheimer et al. 2007; Alvarino et al.
2018), or more in the case of sand filters. Ultrafiltration membranes replace traditional secondary
clarifiers in Levels 4-2 and 5-2. In this capacity they increase total suspended solids removal by
approximately 0.5%, which was considered negligible from the perspective of increasing the
KP-C-16-003; WA 2^37
C-21
-------
Appendix C: Toxic Organics
fraction of toxic organics exiting the WWTP with the sludge fraction. There is however evidence
that certain toxic organics can be sorbed onto hydrophobic filtration membranes via electrostatic
interactions and within the cake layer (Alvarino et al. 2018). Retention of toxic organics on
filtration membranes was not able to be assessed in this study.
Reverse osmosis has been shown to be effective at removing residual toxic organics in
secondary effluent to less-than-detectable levels (Oppenheimer et al. 2007). Reverse osmosis
removal efficiency measurement data was found for 37 of the 43 toxic organic chemicals
considered. Table C-6 lists the low, medium and high removal efficiency estimates calculated
using the 25th percentile, median and 75th percentile of documented values. Data on the removal
efficiency of reverse osmosis was not found for six chemicals. Proxy values that bracket the
extreme values for removal efficiency were used to determine if the removal of these chemicals
is significant in the LCA results. Proxy removal efficiency values of 0%, 49.9%, and 99.9% were
applied in the low, medium and high removal efficiency scenarios, respectively. The selection of
0% and 99.9% in the low and high removal efficiency scenarios was based on the minimum and
maximum removal across the 37 pollutants with reported RO removal efficiency data. The
removal efficiency estimate in the medium removal efficiency scenario is halfway between the
minimum and maximum values.
Table C-6. Toxic Organic Removal Efficiency of Reverse Osmosis
C hemicitl Nitinc
Rciiiox ill
Low
¦^ITiciencv - Rexcrse
Medium
Osmosis
lli»h
acetaminophen
89%
90%
91%
androstendione
31%
62%
71%
atenolol
98%
98%
99%
atorvastatin
98%
98%
99%
atrazine
49%
97%
98%
benzophenone
40%
69%
98%
bisphenol A
98%
99%
99%
butylated hydroxyanisole
98%
98%
99%
butylated hydroxytoluene
98%
98%
99%
butylbenzyl phthalate
98%
98%
99%
carbamazepine
99%
99%
99%
N,N-diethyl-meta-toluamide (DEET)
94%
95%
99%
diclofenac
95%
97%
97%
dilantin
99%
99%
100%
dioctyl phthalate
98%
98%
99%
estradiol
-
80%
92%
estrone
90%
91%
95%
galaxolide
54%
88%
99%
gemfibrozil
98%
99%
100%
hydrocodone
98%
98%
99%
ibuprofen
97%
99%
99%
iopromide
98%
99%
99%
meprobamate
99%
100%
100%
naproxen
94%
96%
99%
nonylphenol
98%
98%
99%
EP-C-I6-QQ3; WA 2^37
C-22
-------
Appendix C: Toxic Organics
Table C-6. Toxic Organic Removal Efficiency of Reverse Osmosis
( hemic:il \:imc
Roiiiox ill
Low
¦ifl'icicncy - Uc\crsc
Medium
Osmosis
Miiili
octylphenol
98%
98%
99%
o-hydroxy atorvastatin
98%
98%
99%
oxybenzone
85%
93%
95%
p-hydroxy atorvastatin
98%
98%
99%
progesterone
-
80%
97%
sulfamethoxazole
98%
99%
100%
TCEP
93%
95%
96%
TCPP
98%
98%
99%
testosterone
49%
97%
98%
triclosan
89%
92%
95%
trimethoprim
99%
99%
100%
triclocarban *
98%
98%
100%
tonalide *
98%
98%
100%
celestolide *
98%
98%
100%
phantolide *
98%
98%
100%
clofibric acid*
98%
98%
100%
musk ketone
56%
68%
19%
diuron *
98%
98%
100%
* Marked and italicized chemicals lack data on removal efficiency and use 0%, 50%, and 100% as proxy removal
efficiency values to determine significance in LCA results.
C. 3.6 Other Processes
Media filtration has not been shown to provide considerable removal beyond that
provided by preceding secondary treatment processes, less than 15 percent (Oppenheimer et al.
2007). Removal efficiency data of standalone sand filters were identified for eight of the 43
pollutants. The low and medium removal efficiency scenarios both assume zero percent removal
based on the 25th percentile and median of the eight identified values. The high removal
efficiency scenarios assume 11% removal, based on the 75th percentile. The described values
were applied to all 43 pollutants and were assumed to constitute additional biodegradation.
Chlorination, dechlorination and the sludge thickening processes were assumed not to
affect the fate of toxic organics within the WWTP.
C. 3.7 Total System Level Performance
Removal efficiency estimates for individual unit processes listed in Table C-2 through
Table C-6 were used as inputs to Equation C-2 to calculate cumulative removal from the liquid
effluent. The fraction of influent toxic organics that accumulate in sludge was estimated by
adding the fraction of removal efficiency attributable to solids partitioning from the combined
primary and secondary biological unit processes (rb x rs) to the additional sludge removal that
results from chemically enhanced secondary clarification (rc) less the fraction of each compound
that is degraded during anaerobic digestion (1-rAD) as summarized in Equation C-2.
Rs-totai = V(xb x rs) + rc] x (1 - rAD)]
KP-C-16-003; WA 2^37
C-23
-------
Appendix C: Toxic Organics
Equation C-2
where
Rs-totai = total fraction of pollutant (in influent) that accumulates in sludge
n = fraction of pollutant removed in primary and secondary treatment, includes
degradation and partitioning to solids.
rs = fraction of primary and secondary removal efficiency attributable to solids
partitioning and sludge removal (percentage of rb).
rc = additional fraction of pollutant removed by chemically enhanced secondary
clarification.
tad = fraction of pollutant degraded during anaerobic digestion.
Table C-7 summarizes the cumulative fate of toxic organics across the nine system
configurations. The presented values represent weighted average degradation and removal
efficiencies across the 43 included chemicals and include the estimated effect of the listed unit
processes. The median influent concentration of the 43 toxic organic chemicals was used as the
weighting factor.
• Primary clarification, biological treatment and secondary/tertiary clarification -
combined removal efficiency. Median values for the Level 1 low, medium and high
removal efficiency scenarios range from 47 to 87% removal. Median values for the
Level 2 through 5 low, medium and high removal efficiency scenarios range from 47
to 93%. Removal efficiency includes partitioning to solids and biodegradation.
• Chemical phosphorus removal - contributes additional partitioning to solids. Median
values for the low, medium and high removal efficiency scenarios range from zero to
34% additional partitioning to solids.
• Sand filtration - assumed to increase biodegradation (minor). Low, medium and high
removal efficiency scenario values range from 0 to 11% removal.
• Anaerobic digestion - biodegrades a fraction of toxic organics that partition to sludge.
Median values for the low, medium and high removal efficiency scenarios range from
0 to 100%) biodegradation.
• Reverse Osmosis - physically separates toxic organics from the liquid stream of
wastewater, concentrating these substances in the brine solution for underground
injection. Median values for the low, medium and high removal efficiency scenarios
range from 98 to 99% removal from the liquid fraction of wastewater.
Table C-7. Summary of Total Toxic Organics Fate in the Nine Treatment Systems3
Tiviilmcnl
Le\el
I- rn
Low
rlion Degrsulc
Mill
il
lli»h
l-'nu-tion li
Low
I'lllOM'll (ilicll
Mill
ilos solids)
1 Null
LI
51.7%
69.9%
84.8%
67.1%
81.1%
89.1%
KP-C-16-001
C-24
-------
Appendix C: Toxic Organics
Table C-7. Summary of Total Toxic Organics Fate in the Nine Treatment Systems3
T resit men I
l-Yiiclion Dcgrsided
l-'niction keimned (includes solids)
l.e\el
Low
Mid
llijih
Low
Mid
llijih
l:-i
51.7%
73.5%
89.7%
67.1%
85.8%
l>4.6%
L2-2
51.7%
73.5%
89.7%
67.1%
85.8%
94.6%
L3-1
51.7%
74.9%
91.6%
67.1%
88.5%
97.0%
L3-2
51.7%
74.9%
91.6%
67.1%
88.5%
97.0%
L4-1
51.7%
74.9%
91.6%
67.1%
88.5%
97.0%
L4-2
51.7%
74.9%
91.2%
67.1%
88.5%
96.7%
L5-1
51.7%
74.9%
91.2%
94.2%
98.5%
99.7%
L5-2
51.7%
74.9%
91.2%
92.7%
98.0%
99.5%
a - Table values represent the cumulative effect of all the described treatment processes, calculated as a weighted
average of the 43 toxic organics using influent concentration as the weighting factor.
C.3.8 Toxicity Characterization Factors
Table C-8 presents the characterization factors used to estimate toxicity impacts
associated with toxic organics in treatment plant effluent and sludge. Not all toxic organics
included in this study have associated characterization factors listed in the most recent versions
of USEtox™, versions 2.02 and 2.11. Characterization factors for several of the pollutants were
previously calculated by other authors (Rahman et al. 2018, Alfonsin et al. 2014).
Characterization factors that were not otherwise available were estimated using the median value
of all other toxic organic pollutants for which data was available. Sources for individual
characterization factors are listed in Table C-8.
KP-C-16-003; WA 2^37
C-25
-------
Appendix C: Toxic Organics
Table C-8. Toxic Organics Toxicity Characterization Factors, USEtox™ version 2.11
(homioiil Nsiino
I SKTo\ ( homioiil Niiinc
l"roslm;ilor
(( 11 o. PAI-
em 1
l-'m issituis
lo
l"roslm;ilor
looio\ioil\.
0(1)
r.niissions
lo
Niilui'iil
Soil
lluiiiiiii lie:
livshwiiK.
CilSOS/k'J;
I'linissioiis
lo
l"ivsh\\;ilor
Illl CilllCCI'.
| (( 11 h.
em i I led)
I'linissioiis
lo Niilur;il
Soil
Illllllilll
IIOIICilllClT.
(( 11 li.i
cm il
I'linissioiis
lo
l-ivslmiilor
1 k;il 111
Voslmiilor
iisos/k'a
O(l)
I'linissioiis
lo
N;ilur;il
Soil
acetaminophen
acetamide
2.6
0.88
2.5E-7
8.5E-8
3.5E-6d
1.4E-7d
androstendione
androstenedione
5.1E+3
5.7E+2
_d
_d
3.5E-6d
1.4E-7d
atenolol
N/A°
1.2E+23
57
_d
_d
8.0E-33
4.0E-33
atorvastatin
N/A°
8.4E+33
4.2E+33
_d
_d
9.6E-83
4.8E-83
atrazine
atrazine
8.7E+4
3.4E+3
3.7E-6
1.5E-7
4.3E-6
1.7E-7
benzophenone
benzophenone
5.2E+3
94
_d
_d
3.5E-6d
1.4E-7d
bisphenol A
bisphenol A
8.dE+3
2.0E+2
-
-
l.lE-6d
2.6E-8d
butylated hydroxyanisole
butylated hydroxyanisole
8.8E+3
1.6E+2
3.4E-7
1.0E-8
3.5E-6d
1.4E-7d
butylated hydroxytoluene
2,6-DI-T-BUTYL-4-
METHYLPHENOL (BHT)
1.8E+3
3.6
3.4E-7
3.6E-9
3.5E-6d
1.4E-7d
butylbenzyl phthalate
phthalate, butyl-benzyl-
5.7E+3
9.1
5.0E-8
1.0E-9
7.3E-8
1.5E-9
carbamazepine
carbamazepine
7.8E+2
93
-
-
2.3E-6
2.8E-7
N,N-diethyl-meta-
toluamide (DEET)
DEET [N,N, -DIET-3 -ME
BENZAMIDE1
2.2E+2
11
-
-
3.5E-6d
1.4E-7d
diclofenac
diclofenac
1.9E+3
1.5E+2
-
-
1.6E-4
1.2E-5
dilantin
phenytoin
1.0E+53
5.0E+43
2.9E-6
1.8E-7
5.3E-43
2.7E-43
dioctyl phthalate
phthalate, dioctyl-
30
0.01
_d
_d
3.5E-6d
1.4E-7d
estradiol
estradiol
2.2E+8
2.3E+6
-
-
1.0E-3b
1.4E-6b
estrone
estrone
2.4E+4
5.7E+2
_d
_d
3.2E-4b
5.4E-7b
galaxolide
N/A3
3.3E+5b
17b
_d
_d
5.0E-7b
4.7E-9b
gemfibrozil
gemfibrozil
7.0E+3d
1.6E+2d
3.1E-6
1.3E-7
3.5E-6d
1.4E-7d
hydrocodone
N/A
1.4E+43
7.0E+33
_d
_d
2.1E-53
1.1E-43
ibuprofen
ibuprofen
2.3E+2
7.3
-
-
3.7E-72
1.7E-82
KP-C-16-003; WA 2^37
C-26
-------
Appendix C: Toxic Organics
Table C-8. Toxic Organics Toxicity Characterization Factors, USEtox™ version 2.11
(honiioiil \;imo
I SKTox ( homioiil Niiinc
l"roslm;i(or
(( 11 o. PAI-
em 1
l-'m issituis
lo
l"roslm;i(or
.on(o\ioi(\.
0(1)
r.niissions
lo
Niilui'iil
Soil
1 liniiiiii he;
IVesIm ilk
Ciisos/ku
Emissions
lo
l-'ivslm silcr
llli csinccr.
im( 11 h.
omillcd)
l-linissioiis
lo \;ilnr;il
Soil
llumsin
nonciiiKTr.
KTl Ik i
em il
Emissions
lo
Fivsliw silcr
Ik'iillh
Voslm;ilor
iisos/k'a
0(1)
I'lmissioiis
lo
N;ilui'iil
Soil
iopromide
iopromide
24
10
-
-
2.4E-7
1.0E-7
meprobamate
N/A°
9.2E+23
4.6E+23
_d
_d
1.0E-ca
5.2E-43
naproxen
N/A°
9.6E+2b
4.9b
_d
_d
3.0E-7b
6.6E-9b
nonylphenol
nonylphenol
1.6E+4
00
00
_d
_d
5.6E-6b
7.1E-10b
octylphenol
N/A°
3.3E+5 b
1.4E+2b
_d
_d
4.3E-6b
3.3E-9b
o-hydroxy atorvastatin
N/A°
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
oxybenzone
N/A°
4.4E+41'
2.2E+43
_d
_d
2.4E-63
1.3E-63
p-hydroxy atorvastatin
N/A°
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
progesterone
N/A°
1.6E+43
7.7E+33
_d
_d
1.3E-53
6.1E-63
sulfamethoxazole
sulfamethoxazole
4.7E+3
1.2E+3
-
-
4.7E-7
1.2E-7
tris(2-
chloroethyl)phosphate
(TCEP)
tris(2-carboxyethyl)phosphine
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
tris(2-chloroisopropyl)
phosphate (TCPP)
TRI-2-CHLOROETHYL
PHOSPHATE
4.4E+2
1.1E+2
1.1E-6
2.8E-7
3.5E-6d
1.4E-7d
testosterone
testosterone
1.3E+4
4.0E+2
_d
_d
3.5E-6d
1.4E-7d
triclosan
5-CHLORO-2-(2,4-
DICHLOROPHENOXY)PHENOL
1.3E+5
8.9E+2
_d
_d
2.2E-7b
5.0E-10b
trimethoprim
trimethoprim
1.0E+3
13
-
-
2.8E-6
3.7E-8
triclocarban
triclocarban
1.4E+6
7.7E+3
_d
_d
3.5E-6d
1.4E-7d
tonalide
N/A°
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
celestolide
N/A°
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
phantolide
N/A°
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
KP-C-16-003; WA 2^37
C-27
-------
Appendix C: Toxic Organics
Table C-8. Toxic Organics Toxicity Characterization Factors, USEtox™ version 2.11
l-'ivslm silcr l"coio\icit>.
((11 e. PAI-" m\(l;iWkK
em i 1 led)
lliiiiiiin liesi 11 h ciinccr.
I'lvsliwiilcr (C 11 h.
csiscs/kg oni il led)
Illllllilll 1 lo;illll
iKtnciinoor. 1'ivslm ;itor
((11 h. csiscs/kg
em il led)
Chomiciil Niimo
I Sl-lTo\ ( Ik-iiiic;il Niiinc
l-'m issituis
lo
l"ivslm;iler
I'm issions
lo
Niilui'iil
Soil
Km issions
lo
l"ivslm;iler
I'm issions
lo Niiiiinil
Soil
I'linissions
lo
l-'ivslm silcr
I'linissions
lo
N;iliii'iil
Soil
clofibric acid
N/A°
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
musk ketone
N/A°
7.0E+3d
1.6E+2d
_d
_d
3.5E-6d
1.4E-7d
diuron
diuron
6.0E+4
4.6E+3
-
-
6.6E-6
5.1E-7
a - Characterizations factors sourced from Rahman et al. 2018.
b - Characterization factors sourced from Alfonsin et al. 2014.
c - Chemical is not present in the current USEtox™ LCIA method,
d - Estimated using the median of toxic organics with available characterization factors.
KP-C-16-003; WA 2^37
C-28
-------
Appendix D: Disinfection Byproducts
APPENDIX D
DETAILED CHARACTERIZATION OF DISINFECTION BYPRODUCT
FORMATION POTENTIAL IN STUDY TREATMENT
CONFIGURATIONS
KP-C-16-003; WA 2^37
-------
Appendix D: Disinfection Byproducts
Appendix D: Detailed Characterization of Disinfection Byproduct Formation
Potential in Study Treatment Configurations
D.l Disinfection Byproducts
Disinfection of wastewater treatment plant (WWTP) effluent is a necessary practice to
minimize the acute risk associated with exposure to microbial pathogens, however it must be
balanced with the chronic risk posed by the creation of disinfection byproducts (DBPs). DBPs
are a class of chemical compounds that can be harmful to both aquatic and human health
(Boorman G A 1999; Nieuwenhuijsen et al. 2000; Mizgireuv et al. 2004; Villanueva et al. 2004;
Muellner et al. 2007; Richardson et al. 2007; Watson et al. 2012). Similar to other emerging
contaminants, the understanding of the occurrence and variety of this class of chemicals is
continually expanding as new analytical techniques enable finer characterization of individual
compounds, though even by 2007 over 600 DBPs had been reported in the literature (Richardson
et al. 2007).
DBPs are formed when DBP precursors, generally organic carbonaceous or nitrogenous
compounds, are oxidized during chlorination or chloramination (Christman et al. 1983). By
regulation, DBPs are managed at drinking water treatment plants, as their presence in water
supplies poses a direct threat to human health (Sedlak and Gunten 2011; U.S. EPA 2015d).
However, as water recycling and reclamation programs expand (and as indirect potable reuse
continues), management of DBPs and DBP precursors has become increasingly important at the
WWTP as well (Krasner et al. 2008; L. Tang et al. 2012).
In the U.S., DBPs are mainly regulated by the U.S. EPA through the Stage 1 and 2
Disinfectants/DBP Rules (U.S. EPA 2015e), which include maximum contaminant levels for the
sum of four trihalomethanes (THM4) and the sum of five haloacetic acids (HAA5) (Table D-l).
Regulation focuses on these two groups, in part, as they generally have the highest
occurrence in drinking water. More importantly however, they serve as indicators for the
presence of other less common, though potentially more toxic, DBPs (Muellner et al. 2007;
Richardson et al. 2007; Krasner et al. 2008). More recently, the US EPA has begun to focus on
these emerging, high priority DBPs (Richardson et al. 2002). Additionally, the California
Department of Health Services established notification levels for several highly toxic
nitrosamines, including iV-Nitrosodimethylamine (NDMA) (Table D-l).
The importance of DBP and DBP precursor control at WWTPs has been growing in
recent years for several reasons. First, the type of precursors formed through biological
wastewater treatment are complex and, although overlapping with, are in many ways dissimilar
from the natural organic matter (NOM)-derived precursors of drinking water-based DBPs. For
example, effluent organic matter (EfOM) is generally composed of NOM, synthetic organic
compounds and soluble microbial products (SMP) (Doederer et al. 2014), the latter of which can
be further decomposed into organic compounds generated during biological treatment processes
including (but not limited to) humic and fulvic acids, polysaccharides, proteins, nucleic acids,
organic acids, amino acids, structural components of cells and products of energy metabolism
(Barker and Stuckey 1999). Given this potential chemical diversity, lessons learned in drinking
KP-C-16-003; WA 2^37
D-l
-------
Appendix D: Disinfection Byproducts
water DBP formation prediction and control are not directly translatable (Drewes and Croue
2002; L. Tang et al. 2012).
In addition to precursor complexity, there has been increasing concern over emerging and
more toxic nitrogenous DBPs such as nitrosamines, halonitroalkanes, haloacetonitriles (HANs)
and haloacetamides (Westerhoff and Mash 2002; Joo and Mitch 2007; Lee et al. 2007).
Haloacetamides and HANs in particular are approximately two orders of magnitude more
cytotoxic and genotoxic than the regulated THMs and HAAs (Muellner et al. 2007; Plewa and
Wagner 2009). The precursors for these nitrogenous DBPs are mostly dissolved organic nitrogen
(DON) compounds, which are removed to varying degrees depending on the type of treatment
process utilized. Secondary effluents are particularly rich in DON (Huang et al. 2016), which can
be removed to varying degrees through the addition of nitrification and denitrification biological
nutrient removal (BNR) processes (Huo et al. 2013). However, in a study of an A20 (anaerobic,
anoxic, oxic), AO (anaerobic, oxic) and MBR treatment, it was found that approximately half of
wastewater-derived DON was of low molecular weight (capable of passing through a 1 kDa
ultrafilter) which is not effectively removed by BNR processes (Huo et al. 2013). Moreover, the
low molecular weight fraction that remains after biological treatment also tends to be
hydrophilic, which is challenging for even chemical and physical methods to remove
(Pehlivanoglu-Mantas and Sedlak 2008; Huo et al. 2013).
A further complication is the effect of nitrogen, ammonia in particular, on the reaction
kinetics of chlorination and chloramination. For example, formation of halogenated DBPs like
THMs and HAAs can be greatly reduced if free chlorine is minimized in the disinfection process
(Krasner et al. 2009b). This is done by either using chloramines directly or maintaining the Ch/N
(mass/mass) ratio below 10 so that any free chlorine is quenched by ammonia. Ironically
however, this effective control of halogenated DBPs favors the formation of more toxic
nitrogenous DBPs like NDMA, especially when applied to poorly nitrified (high DON) effluent
(Krasner et al. 2008; Sedlak and Gunten 2011). Thus, the presence of precursors does not
necessarily entail DBP formation, which further depends on site-specific operational
characteristics like disinfection practices.
Last, DBP precursors formed in biological treatment processes can potentially be
recalcitrant, as they are generally composed of cellular debris leftover from substrate metabolism
and biomass decay (Barker and Stuckey 1999). Owing to this potential recalcitrance, there is
evidence of persistence at least on the order of days, which is of relevance for a typical river
indirect potable reuse scenario. In a multi-season survey of a river determined to be effluent
dominated (determined through use of primidone, a conservative wastewater tracer), Krasner et
al. (2008) documented the presence of EfOM-derived nitrogenous DBP precursors at
downstream locations, including the intake of a water treatment plant, with concentrations that
suggested dilution, not degradation, to be the primary attenuation mechanism. Results for
carbonaceous precursors, which tend to be humic compounds, were masked by the naturally high
humic content of the river water.
Given that the formation potential of DBPs is dependent upon numerous variables which
can change daily, for purposes of this study, it was decided to use the formation potential (FP) of
DBPs (DBPFP) as a more conservative indicator of the concentration of DBPs that could be
formed by the various treatment configurations used in this study. Moreover, FP is determined
KP-C-16-003; WA 2^37
D-2
-------
Appendix D: Disinfection Byproducts
using a standardized procedure, eliminating variability that may arise owing to different
disinfection practices, allowing for a clearer distinction between the effects of different treatment
approaches on precursor control. Accordingly, to characterize the effects of the nine Study
configurations on DBP formation, a comprehensive dataset linking effluent water quality to
DBPFP was used for this analysis (Krasner et al. 2008). The DBP and DBP groups included in
the study included the regulated carbonaceous DBPs (THMs and HAAs) along with emerging
and more toxic carbonaceous and nitrogenous DBPs and are outlined in Table D-l. The general
approach is discussed further below.
Table D-l. Summary of Regulated Disinfection Byproducts
Rciiiihilon
DliP (^roiip/compoiind)
( haraclerislics
Precursors
l.imil
An I lioril >
Trihalomethanes (THM)1'2
Chloroform
influent refractory
U.S. EPA,
Stage 1/2 DBP
Rule
Bromodichloromethane (BDCM)
carbonaceous,
NOM, EfOM,
80 ng/L
Chlorodibromomethane (DBCM)
halogenated
nitrified effluent,
(TTHM)
Bromoform
humic compounds
Haloacetic Acids (HAA)2'3
Monochloroacetic acid
influent refractory
NOM, EfOM,
nitrified effluent,
humic compounds
Dichloroacetic acid (DXAA)
carbonaceous,
halogenated
60 ng/L
(HAA5)
U.S. EPA,
Trichloroacetic acid (TXAA)
Stage 1/2 DBP
Bromoacetic acid
Rule
Dibromoacetic acid
Nitrosamines4
.Y-nitrosodimcthvlamine (NDMA)
nitrogenous,
unhalogenated
DON,
dimethylamine
10 ng/L
CA (action
level)
Aldehydes
Formaldehyde
Acetaldehyde
carbonaceous,
halogenated
Chloroacetaldehyde
DON, amino acids
NA
NA
Dichloroacetaldehyde
Trichloroacetaldehyde (chloral hydrate)
Haloacetonitriles (HANs)
Chloroacetonitrile
Bromoacetonitrile
Iodoacetonitrile
nitrogenous,
halogenated
T richloroacetonitrile
DON, amino acids
NA
NA
Bromodichloroacetonitrile
Dibromochloroacetonitrile
T ribromoacetonitrile
1 The four compounds together comprise the four primary trihalomethanes, sometimes referred to as TTHM or
THM4
2 (U.S. EPA2015d)
^ These five compounds together comprise the five primary haloacetic acids, sometimes referred to as HAA5
4 California Department of Health Services, action level
KP-C-16-003; WA 2^37
D-3
-------
Appendix D: Disinfection Byproducts
D.2 Methods
The results of a comprehensive survey of the effluent DBPFP of 23 U.S. WWTPs
(Survey) were used to construct multiple linear regression models (Models) for the prediction of
DBPFP based on effluent water quality (Krasner et al. 2008; Krasner et al. 2009a). The Survey
was conducted at WWTPs that utilize a range of common treatment technologies with differing
abilities to control DBP precursors, including humic substances, amino acids and other organic
nitrogen compounds. The treatment processes included oxidation ditch, aerated lagoon, trickling
filter, activated sludge, nitrification/denitrification, soil aquifer treatment (SAT), powdered
activated carbon (PAC) and granular activated carbon (GAC), MBR, RO and various
combinations. A primary objective of the Survey was to establish a database of water quality and
operational parameters that could be used to evaluate global and site-specific correlations
between water quality and DBPFP.
In order to draw meaningful conclusions from the Survey, the authors divided the 23
WWTPs into nine general categories according to the dominant biological or physical treatment
process. Figure D-l shows the resulting water quality ranges of Survey categories (25th, 50th and
75th percentiles), along with effluent quality of the nine Study configurations plotted against their
most similar Survey category. Although additional water quality parameters were measured in
the Survey, only those relevant parameters (i.e. carbonaceous or nitrogenous) that were also
defined for Study configurations (Table 1-4) were used in this analysis.
As can be seen from Figure D-l, although many Study configurations fit within the
second first and third quartiles (between the 25th and 75th percentile of results) of at least one
Survey category, some parameters fall outside of any range. This is especially true for COD,
which is particularly important as a surrogate for carbonaceous DBP precursors. Accordingly, a
direct translation of Survey categories to Study configurations is not fully appropriate. Therefore,
a multiple linear regression modelling approach was used to estimate which water quality
parameters were most appropriate for predicting DBPFP, and their approximate effect.
KP-C-16-003; WA 2^37
D-4
-------
Appendix D: Disinfection Byproducts
35
30
25
M 20
E_
5 15
10
5
0
TKN
aja
0- so# >
kN
^ . c«
rrj =
* +
e°°~
25
20
15
m
5 10
NH3
0
£W1 E3K3
H
y
v~
/V
op^ #' ^
$? «o* JT' J*
r ^ *°
^ ^ ^ ~°'
^ N°^ }
0°
o-y g>°
20
18
16
14
1 12
— 10
N03-
m
O
8
6
4
2
0
$
K
(V
.rV- (A . ST O
90 -N
#¦ N<* <#•
*v^c/
— Level 1, AS
O Level 2-2, AS3
O Level 3-2, MUCT
X Level 4-2, MBR
+ Level 5-2, MBR/RO
,o
N«-
+
.+.
9-°
40
35
30
5 25
t*o
^20
o
S 15
10
5
0
COD
sQSgB
m
rf> v >S-' V
J>0 ^ J>° °" ^ Qo6
9V 0>°
O Level 2-1, A20
O Level 3-1, B5
X Level 4-1, B5/Denit
¦ Level 5-1, B5/RO
— Level 1, AS
O Level 2-2, AS3
O Level 3-2, MUCT
X Level 4-2, MBR
+ Level 5-2, MBR/RO
O Level 2-1, A20
O Level 3-1, B5
X Level 4-1, B5/Denit
¦ Level 5-1, B5/RO
Figure D-l. Statistical summary of Survey category water quality, along with Study
configuration water quality plotted within the most applicable Survey category. Ranges
represent second and third quartiles, or 25th/50th/75th percentiles (Krasner et al. 2008;
Krasner et al. 2009).
EP-C-16-003: WA 2-37
D-5
-------
Appendix D: Disinfection Byproducts
First, a linear correlation analysis was performed between relevant water quality
parameters and DBPFP, using median values from each Survey category as input. Table D-2
shows the resulting correlations, in terms of the coefficient of determination (R2). As shown,
COD is the largest predictor of DBPFP for each DBP group, followed in most cases by TKN.
Table D-2. Linear Correlation Analysis between Median Water Quality Parameters and
Median DBPFP for Survey Categories
CodTicicnl of Dclcrmiiiiilion (U~)
l)lil»l l»
COD
TKN
Nil.*
N()3
THiYls
0.86
0.09
0.07
0.05
HANs
0.79
0.72
0.68
0.01
DXAAs
0.99
0.29
0.26
0.03
TXAAs
0.86
0.24
0.20
0.05
dihaloacetaldehydes
0.88
0.59
0.57
0.00
trihaloacetaldehydes
0.85
0.55
0.50
0.01
NDMA
0.73
0.18
0.20
0.00
Given the predictive ability of both COD and TKN especially, multiple linear regression
models were constructed for each DBP group. Models were constructed in a stepwise fashion.
Starting with COD as a single predictor, additional predictors were incorporated following the
order of their coefficient of determination (Table D-2). Final Models reflect the combination of
predictors that resulted in the greatest adjusted R2. Although NFb was in many cases nearly as
predictive as TKN, its contribution to overall model fit was generally less than TKN (i.e. the
adjusted R2 of models with COD and TKN were generally greater than that of models with COD
and NH3). Resulting Model coefficients, adjusted R2 and overall significance (F) are provided in
Table D-3. For DXAAs and TXAAs, COD alone provided the greatest predictive power
(adjusted R2). To illustrate the Models' predictive capabilities, Figure D-2 shows Model results
using median water quality values for each Survey category as input, plotted against their actual
DBPFP ranges (second first and third quartiles). As shown, the Models are capable of predicting
DBPFP within the 25th to 75th percentile ranges for most DBP categories, with the main
exception of the Partial or Poor Nitrification and Good Nitrification categories for NDMA.
Importantly however, the Models capture the low DBPFP provided by RO, which ultimately will
provide for greater predictive capability in the water quality ranges not represented by Survey
categories but occupied by many of the Study configurations (recall Figure D-l).
Table D-3. Multiple Linear Regression Model Parameters, Fit and Significance
l)lil>
COD
C'oclTicicnl
TKN
111 Icrccpl
Ail j listed
V
1
(Si*»n i 1".)
THMs
11.09
-3.68
3.66
0.89
0.005
HANs
0.59
0.58
-1.58
0.96
0.001
DXAAs
5.31
-4.15
0.99
0.000
TXAAs
4.57
-0.87
0.83
0.003
dihaloacetaldehydes
0.21
0.12
-0.63
0.95
0.001
KP-C-16-003; WA 2^37
D-6
-------
Appendix D: Disinfection Byproducts
Table D-3. Multiple Linear Regression Model Parameters, Fit and Significance
DBP
Coefficient
Adjusted
R2
F
(Signif.)
COD
TKN
Intercept
trihaloacetaldehydes
2.30
1.19
-5.34
0.89
0.006
NDMA
27.92
-2.52
-13.65
0.60
0.072
+ 00 ~ a
rS .<5
P* #'
&
DXAAs
—
-1 m
-r
Q a
.
Av V 00 ,
csc? J-
1600
_ 1400
< 1200
ao
.5.1000
£fc 800
| 600
| 400
200
0
NDMA
+ +
IS
CP^
,\v
-------
Appendix D: Disinfection Byproducts
associated characterization factors listed in the most recent versions of USEtox™, versions 2.02
and 2.11. Characterization factors that were not otherwise available were estimated using the
median value of all other DBPs for which data was available. Sources for individual
characterization factors are listed in Table D-4.
Table D-4. DBP Toxicity Characterization Factors, USEtox™ version 2.11
( homiciil
\;imo/( hiss
I Sl.lnx ( homioiil
N;i mo
l"roslm;Mor
leo(o\ieh\.
((11 o. I\\l-
nr'.ri.iWkg em i I led)
1
lluiiiiiii lleiillh
o;inoor. I'rcslm ;iler
((11 h. c;isos/kii
cm il (od)
'.missions lo l-'rosh\\;il
lllllllilll llOilllll
nonoiiiiooi'.
IVoslmiilor (C 11 li.
o;isos/k'j; oiiiillod)
.'i-
trihalomethane sa
N/A°
90
5.2E-7
8.0E-7
haloacetonitriles
chloroacetonitrile
7.6E+3
3.6E-7b
4.5E-7b
dichloroacetic
Acid
dichloroacetic acid
52
6.7E-7
1.1E-6
trichloroacetic
acid
trichloroacetic acid
34
2.9E-7
4.5E-7b
dihaloacet-
aldehydes
N/A°
1.9E+2b
3.6E-7b
4.5E-7b
trihaloacet-
aldehydes
chloral hydrate
2.5E+2
3.6E-7b
4.5E-7b
nitrosamines
N-
nitrosodimethylamin
e
25
7.9E-4
N/A
a - Average of trichloromethane/chloroform, bromodichloromethane, dibromochloromethane, and tribromomethane.
b - Estimated using the median of DBPs with available characterization factors,
c - Chemical is not present in the current USEtox™ LCIA method.
D.3 Results and Discussion
Table D-5 and Figure D-3 give Model results for the nine Study treatment configurations.
Effluent COD and TKN values (Table 1-4) were used as input, along with coefficients and
intercepts given in Table D-3.
Table D-5. DBPFP Model Results for Study Treatment Configurations
TIIMs
IIANs
DXAAs
TXAAs
clihiiloiHTl-
iildohydos
IrihnloiH-ot-
sildclmlcs
M)MA
Sludv ( <)iili
-------
Appendix D: Disinfection Byproducts
300
250
200
150
100
50
Disinfection Byproduct Formation Potential
800
NDMA Formation Potential
' 600
400
z 200
I.. 11
Level 1
AS
Level 2-1
A20
Level 2-2
AS3
Level 4-1
B5/Denit
Level 4-2
MBR
Level 5-1 Level 5-2
B5/RO MBR/RO
iTHMs DDXAAs DTXAAs Dtrihaloacetaldehydes ~ HANs Ddihaloacetaldehydes
Figure D-3. DBPFP Model results for Study treatment configurations.
The formation potentials presented above are an upper bound to what could be formed at
the WWTP. Using THMs as an example, ranges of THMs that actually formed at the surveyed
WWTPs were also a function of chlorine dose and the Cb/N ratio. When the Cb/N ratio was
above 10, allowing for the creation of free chlorine and enhanced THM formation, the 10th and
90th percentile concentrations of THMs were 20 ug/L and 80 |ig/L, respectively (Krasner et al.
2009b). Compared to the formation potentials determined for each of the Survey groups
(illustrated in Figure D-2) with medians largely in the range of 200-250 ug/L, this implies that
upon discharge, there remains considerable additional formation potential in the form of
unreacted precursors. Similarly, when the Cb/N ratio was less than 10, favoring chloramine
creation and NDMA formation, the 10th and 90th percentile of observed concentrations of NDMA
were 4 and 122 ng/L, compared to formation potentials that were sometimes an order of
magnitude greater (also illustrated in Figure D-2). Thus, depending on factors like chlorination,
temperature and pFI (Doederer et al. 2014), which are assumed constant in Study configurations,
formation of DBPs prior to discharge may be on the order of 10-50% of the formation potentials
indicated above in Table D-5 and Figure D-3.
EP-C-16-003: WA 2-37
D-9
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Appendix E: Detailed Cost Methodology
APPENDIX E
DETAILED COST METHODOLOGY
KP-C-16-003; WA 2^37
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Appendix E: Detailed Cost Methodology
Appendix E includes supporting details for the methodology used to estimate costs
associated with the nine wastewater treatment configurations. Appendix E. 1 presents the unit
design values for the unit processes included in CAPDETWorks™. Appendices E.2, E.4, B.4,
E.6, and E.7 present the detailed cost methodologies for the dechlorination, ultrafiltration,
reverse osmosis, and deep well injection, respectively. Appendix E.8 presents the
CAPDETWorks™ file used to develop the direct cost factors discussed in Section 3.3.1.
E.l CAPDETWorks™ Process Unit Design Values
This appendix includes the initial CAPDETWorks™ design values for the unit processes
included in the nine wastewater treatment configurations. As discussed in Section 3.2.2, ERG
revised some of the design values during development of the CAPDETWorks™ models to
achieve the effluent wastewater objectives for each treatment level and/or address warnings in
the CAPDETWorks™. For example, CAPDETWorks™ calculates the number of mixers for the
Biological Nutrient Removal 3/5 Stage and provides a warning if the horsepower (HP) per mixer
exceeds the CAPDETWorks™ recommended 5 HP/mixer. In this instance, ERG increased the
number of mixers to eliminate the warning so the design reflected all of the equipment necessary.
The final design values used for each wastewater treatment configuration are included in the
final CAPDETWorks™ cost output discussed in Section 5. The following unit processes are not
in CAPDETWorks™: modified University of Cape Town, 4-stage Bardenpho, fermentation,
ultrafiltration, reverse osmosis (including pretreatment), deep well injection for brine disposal,
and dechlorination. Costs for these unit processes were developed outside of CAPDETWorks™
and are documented in Sections 3.2.3.1 through 3.2.3.7 of this report.
ERG reviewed EPA's Municipal Nutrient Removal Technologies Reference Document
(U.S. EPA OWM, 2008b), WERF's Striking the Balance Between Nutrient Removal in
Wastewater Treatment and Sustainability (Falk, 2011), EPA/ORD's Nutrient Control Design
Manual (U.S. EPA ORD, 2010), and additional EPA wastewater treatment process fact sheets to
confirm that the CAPDETWorks™ default design values (Hydromantis, 2014) are appropriate
for use for this study. Based on our review, ERG used the CAPDETWorks™ default design
values for the unit processes below that are included in one or more of the wastewater treatment
configurations. Appendix E. 1.14 includes key parameters and the default design values for these
unit processes (Hydromantis, 2014).
• Membrane Bioreactor
• Sand Filter
• Centrifugation - Sludge
The remainder of Section E. 1 provides the initial design values used for each of the
remaining CAPDETWorks™ unit processes included in the nine wastewater treatment
configurations.
KP-C-16-003; WA 2^37
E-l
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E. 1.1 Preliminary Treatment — Screening and Grit Removal
The default Preliminary Treatment design values were used. Key parameters and default
design values for Preliminary Treatment - Screening include:
• Cleaning Method: Mechanically Cleaned
Key parameters and default design values for Preliminary Treatment - Grit Removal
include:
• Type of Grit Removal: Horizontal
• Number of Units: 2
• Volume of Grit: 4.0 ft3/MGal
• Detention Time: 2.5 min
However, the resulting purchased equipment costs were about half the construction costs
presented in Wastewater Technology Fact Sheet - Screening and Grit Removal (U.S. EPA,
2003b). As a result, ERG doubled the CAPDETWorks™ Preliminary Treatment purchased
equipment costs for all nine wastewater treatment configurations.
E. 1.2 Primary Clarifier
The default Primary Clarifier design values were modified as follows, as recommended
in Wastewater Engineering: Treatment and Resource Recovery (Tchobanoglous et al., 2014):
• Sidewater depth: 12.0 ft (instead of 9.0 ft)
• Underflow concentration: 3.5% (instead of 4.0%)
Note that this sidewater depth and underflow concentration are within
CAPDETWorks™'s recommended ranges (7-12 ft and 3-6%, respectively) (Hydromantis, 2014).
Additional key parameters and default design values for Primary Clarifier include:
• Type of Clarifier: Circular
• Surface Overflow Rate: 1,000 gal/ft2-d
• Weir Overflow Rate: 15,000 gal/ft-d
• Suspended Solids Removal: 58%
• BOD Removal: 32%
• COD Removal: 40%
• TKN Removal: 5%
• Phosphorous Removal: 5%
EP-C-16-003; WA 2^37
E-2
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E. 1.3 Plug Flow Activated Sludge
Because the Level 1 wastewater treatment configuration represents a system that is not
designed for nitrogen removal, and Level 2-2 requires higher effluent ammonia levels for the
subsequent nitrification/denitrification processes, the default Plug Flow Activated Sludge design
values was modified as follows:
• Process Design: Carbon Removal Only (instead of default Carbon Plus Nitrification)
Additional key parameters and default design values for Plug Flow Activated Sludge
include:
• Aeration Type: Diffused Aeration
• Bubble Size: Fine Bubble
• Solids Retention Time (SRT): 10 days
• Mixed Liquor Suspended Solids (MLSS): 2,500 mg/L
E. 1.4 Biological Nutrient Removal 3/5 Stage
When used for the Anaerobic/Anoxic/Oxic (A20) unit process in Level 2-1, the default
Biological Nutrient Removal 3/5 Stage design values were modified as follows:
• Number of Stages: 3-Stage (instead of 5-Stage)
• Internal Recycle from Anoxic to Anaerobic Zone: No (the A20 process does not
include this recycle)
• Internal Recycle from the Oxic to Anoxic Zone: Yes
• Assume sufficient carbon in the wastewater to denitrify without an additional carbon
source
• Effluent Total Kjeldahl Nitrogen (TKN): modified to achieve the 8 mg/L target
effluent total nitrogen (TN) concentration
• Effluent Total Phosphorous (TP): modified to achieve the 1 mg/L target effluent TP
concentration
When used for the 5-Stage Bardenpho unit process in Levels 3-1, 4-1, 5-1, and 5-2, the
default Biological Nutrient Removal 3/5 Stage design values were modified as follows:
• Number of Stages: 5-Stage (instead of 3-Stage)
• Internal Recycle from Anoxic to Anaerobic Zone: No
• Internal Recycle from the Oxic to Anoxic Zone: Yes
• Effluent TKN: modified to achieve the target effluent total nitrogen concentrations of:
— Level 3-1:4-8 mg/L TN
— Level 4-1: 3 mg/L TN
EP-C-16-003; WA 2^37
E-3
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— Levels 5-1 and 5-2: 2 mg/L TN
• Effluent TP: modified to achieve the target effluent total phosphorous concentrations
of:
— Level 3-1: 0.1-0.3 mg/L TP
— Level 4-1: 0.1 mg/L TP
— Levels 5-1 and 5-2: <0.2 mg/L TP
In addition to the specific modifications proposed above, for instances when
CAPDETWorks™ provided a warning that the number of mixers was insufficient for each mixer
to be less than 5 HP/mixer, the CAPDETWorks™ default number of mixers per tank was
increased until the mixers were less than 5 HP/mixer.
Additional key parameters and default design values for Biological Nutrient Removal 3/5
Stage include:
• Aeration Type: Diffused Aeration
• Bubble Size: Fine Bubble
• Total Reactor SRT: 15 days
E. 1.5 Denitrification — Suspended Growth
The default Denitrification - Suspended Growth design values were modified for effluent
nitrate to achieve the effluent total nitrogen concentration target for Level 2-2 of 8 mg/L TN.
In addition to the specific modifications proposed above, for instances when
CAPDETWorks™ provided a warning that the number of mixers was insufficient for each mixer
to be less than 5 HP/mixer, the CAPDETWorks™ default number of mixers per tank was
increased until the mixers were less than 5 HP/mixer.
Additional key parameters and default design values for Denitrification - Suspended
Growth include:
• Design SRT: 10 d
• MLSS: 2,500 mg/L
E. 1.6 Denitrification — Attached Growth
The default Denitrification - Attached Growth design values were modified as follows:
• Allowable Effluent Nitrate:
— Level 4-1: 3 mg/L TN
— Levels 5-1 and 5-2: <0.02 mg/L TN (taking into consideration the RO TN
removal)
• Application Rate: 1.5 gal/ft2-min (instead of 1.0 gal/ft2-min)
KP-C-16-003; WA 2^37
E-4
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The recommended application rate matches that used in the analysis in WERF's Striking
the Balance Between Nutrient Removal in Wastewater Treatment and Sustainability (Falk, 2011)
and is more aligned with actual plant application rates of 2.2 and 3.0 gal/ft2-min, as presented for
two plants in the Municipal Nutrient Removal Technologies Reference Document (U. S. EPA
OWM, 2008b). Note that this application rate is outside of CAPDETWorks™' recommended
range (0.5 to 1.0 gal/ft2-min). ERG reviewed the underlying cost curves for CAPDETWorks™'
construction and O&M costs and considers the outputs to be reasonable at the 1.5 gal/ft2-min
application rate.
Additional key parameters and default design values for Denitrification - Attached
Growth include:
• Methanol Requirement: 3 lb/lb NO3
• Backwash Rate: 12 gal/ft2-min
E. 1.7 Nitrification - Suspended Growth
Because SRT is a key factor for achieving nitrification, the default Nitrification -
Suspended Growth design values were modified as follows for the reasons described below:
• Design Basis: Specify Design SRT (instead of default Temperature Specific Growth
Rates or pH Ammonia Sensitive Rates)
• Design SRT: 50 d (instead of 10 d)
Note that using a design basis that specifies the default Temperature Specific Growth
Rates returned a unit design with a SRT of 5.89 hrs and hydraulic residence time (HRT) of 1.27
hrs, well below recommended SRT and HRT values12. Using a SRT of 24 d and the default
MLSS of 2,500 mg/L returns a unit design with a HRT of 3.11 hrs, which is still below
CAPDETWorks™ recommended minimum. A SRT of 50 d and the default MLSS of 2,500
mg/L returns a unit design with a HRT of 6.31 hours. These values are similar to those of the
Western Branch WWTP with a 3-sludge system designed to achieve 1.0 mg/L effluent TP and
3.0 mg/L effluent TN. The Western Branch WWTP has nitrifying activated sludge system SRT
ranging from 21.4 days (June) to 84.6 days (September), with an average of 47.6 days (U.S. EPA
OWM, 2008b). As a result, ERG's recommended 50 d design SRT is reasonable.
Additional key parameters and default design values for Nitrification - Suspended
Growth include:
• Aeration Type: Diffused Aeration
• Bubble Type: Fine Bubble
• MLSS: 2,500 mg/L
12 A SRT of 24 days is recommended for general nitrification systems from Municipal Nutrient Removal
Technologies Reference Document (U.S. EPA OWM, 2008b) and a minimum HRT of 6 hrs from CAPDETWorks™
(Hydromantis, 2014).
KP-C-16-003; WA 2^37
E-5
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E. 1.8 Chemical Phosphorus Removal
The default effluent phosphorus concentration target for each level that includes chemical
phosphorous removal was adjusted to achieve the following effluent total phosphorous
concentration targets:
• Level 2-2: 1 mg/L TP
• Levels 3-1 and 3-2: 0.3 mg/L TP
• Levels 4-1, 4-2, 5-1, and 5-2: 0.1 mg/L TP (remaining TP to achieve <0.02 mg/L
effluent target for Level 5 configurations will be achieved with RO)
In addition, ERG revised the default chemical dosage to two times the stoichiometric
alum dose, as recommended by the Municipal Nutrient Removal Technologies Reference
Document (U.S. EPA OWM, 2008b).
Additional key parameters and default design values for Chemical Phosphorous Removal
include:
• Metal Precipitant: Equivalent Aluminum
E.1.9 Secondary Clarifier
The default Secondary Clarifier design values were modified as followed:
• Surface overflow rate: 600 gal/ft2-d (instead of 500 gal/ft2-d)
• Sidewater depth: 14.5 ft (instead of 9.0 ft)
The surface overflow rate was modified to match WERF's Striking the Balance Between
Nutrient Removal in Wastewater Treatment and Sustainability (Falk et al, 2011). Note that this
surface overflow rate is within CAPDETWorks™' recommended range (200 to 800 gal/ft2-day)
(Hydromantis, 2014). CAPDETWorks™' background documentation generally describes that
lower overflow rates are more appropriate for smaller plants and higher overflow rates are more
appropriate for larger plants (Hydromantis, 2014). The sidewater depth and underflow
concentrations were modified to within ranges recommended in Wastewater Engineering:
Treatment and Resource Recovery (Tchobanoglous et al., 2014). Note that the sidewater depth is
within CAPDETWorks™'s recommended ranges (7-15 ft) (Hydromantis, 2014).
Additional key parameters and default design values for Secondary Clarifier include:
• Underflow concentration: 1%
• Weir Overflow Rate - Maximum 15,000 gal/ft-d
• Effluent Suspended Solids: 20 mg/L
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E-6
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E.1.10 Chlorination
Chlorination using liquid hypochlorite is more common that gaseous chlorine due to
safety concern and regulations on the handling and storage of pressurized liquid chlorine
(Tchobanoglous et al., 2014). However, this analysis assumes use of gaseous chlorine because
that is the only disinfection alternative used by CAPDETWorks™ (Hydromantis, 2014).
When used for wastewater treatment configurations where solids removal is completed
with clarifiers (Level 1, Level 2-1, and Level 2-2), the default Chlorination design values were
modified as follows:
• Contact Time at Peak Flow: 30 min
• Chlorine Dose: 10 mg/L
When used for wastewater treatment configurations where solids removal is completed
with a sand filter or membrane bioreactor (Level 3-1, Level 3-2, Level 4-1, and Level 4-2), the
default Chlorination design values were modified as follows:
• Contact Time at Peak Flow: 30 min
• Chlorine Dose: 8 mg/L
When used for wastewater treatment configurations with the majority of the flow going
through reverse osmosis (Level 5-1 and Level 5-2), the default Chlorination design values were
modified as follows:
• Contact Time at Peak Flow: 30 min
• Chlorine Dose: 5 mg/L
ERG developed these design input value recommendations based on consideration of
CAPDETWorks™ default design values (Hydromantis, 2014) and assumptions provided in
Striking the Balance Between Nutrient Removal in Wastewater Treatment and Sustainability
(Falk et al, 2011), which were further supported based on an evaluation of design information
provided in EPA's Onsite Wastewater Treatment Systems Manual (EPA, 2002).
E.l.ll Gravity Thickener
The default Gravity Thickener design values were modified as follows:
• Based On: Mass Loading (instead of Settling)
• Mass Loading: 30 lb/ft2-d (instead of 10 lb/ft2-d)
• Underflow Concentration: 4.0% (instead of 5.0%)
• Depth: 11.5 ft (instead of 9 ft)
• Standard 90 ft Diameter Thickener: $1,000,000 (instead of $154,000)
KP-C-16-003; WA 2^37
E-7
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Note that using the default Settling design basis returned a unit design with a HRT of
20.3 hr, well above recommended HRT values (maximum HRT of 6 hrs from CAPDETWorks™
(Hydromantis, 2014)). As a result, ERG used CAPDETWorks™ maximum recommended mass
loading rate rather than the default design value of 10 lb/ft2-d to reduce the gravity thickener
HRT and the risk of creating anaerobic conditions that can lead to phosphorous release from the
sludge. Using the recommended mass loading results in a HRT of 6.78 hrs, which is reasonable
compared to CAPDETWorks™ recommended 6 hr maximum (Hydromantis, 2014).
The underflow concentration was modified to within the range in Wastewater
Engineering: Treatment and Resource Recovery (Tchobanoglous et al., 2014). The depth was
modified to within the range recommended in Biosolids Technology Fact Sheet - Gravity
Thickening (U.S. EPA. 2003a). The standard 90 ft diameter thickener cost was modified to
$1.000.000 so the gravity thickener purchased equipment cost was comparable to the costs in
Biosolids Technology Fact Sheet - Gravity Thickening (U.S. EPA. 2003a).
E.1.12 Anaerobic Digestion
The default Anaerobic Digestion design values were modified to match the Gravity
Thickener underflow concentration (see Section E. 1.11) as follows:
• Concentration in Digester: 4.0% (instead of 5.0%)
Note that this concentration in digester is within CAPDETWorks™' recommended range
(3 to 7%) (Hydromantis, 2014).
Additional key parameters and default design values for Anaerobic Digestion include:
• Percent Volatile Solids Destroyed: 50%
• Minimum Detention Time in Digester: 15 d
• Fraction of Influent Flow Returned as Supernatant: 2%
• Supernatant Concentrations:
— Suspended Solids: 6,250 mg/L
— BOD: 1,000 mg/L
— COD: 2,150 mg/L
— TKN: 950 mg/L
— Ammonia: 650 mg/L
E.1.13 Haul and Landfill - Sludge
ERG modified the following default design values as follows to correspond with the 25
mi one-way distance used in the ORCR CCR rule (ERG, 2013):
• Distance to Disposal Site: 25 mi one way
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E-8
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• Disposal Cost Based On: Sludge Disposal per Ton
E.1.14 Key Default Design Parameters for Select Unit Processes
Membrane Bioreactor
Key parameters and default design values for Membrane Bioreactor include:
• Average Net Flux: 20 L/m2-hr
• Effluent Suspended Solids: 1.0 mg/L
• Underflow Concentration: 1.2%
• Scour Air Cycle Time: 20 s
• Scour Air On Time: 10 s
• Physical Cleaning Interval: 9 min
• Physical Cleaning Duration: 1 min
• Chemical Cleaning Interval: 7 days
• Backflush Flow Factor: 1.25
Sand Filter
Key parameters and default design values for Sand Filter include:
• Number of Layers: 4
• Layer 1: Anthracite
• Layers 2, 3, and 4: Sand
• Loading Rate: 6 gpm/ft2
• Backwash Time: 10 min
Centrifugation - Sludge
Key parameters and default design values for Centrifugation - Sludge include:
• Cake Solids Content: 9%
• Solids Capture: 90%
• Number of Units: 2
• Operation: 8 hr/d for 5 d/wk
KP-C-16-003; WA 2^37
E-9
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E.2 Dechlorination
Listed below are the capital cost elements included for dechlorination using sodium
bisulfite (NaHSCb), with a general description of the basis of estimate, followed by the O&M
cost elements and the basis of estimate.
Capital Costs
1. Dechlorination Contact Tank, Dechlorination Building, Chemical Storage
Building, and Miscellaneous Items (e.g., grass seeding, site cleanup, piping).
Costed in 2014 $ using the CAPDETWorks™ chlorination unit process and
selecting unit process input values to simulate dechlorination rather than
chlorination.
• Revised the CAPDETWorks™ input contact time at peak flow to 5
minutes to reflect the dechlorination unit contact time:
— CAPDETWorks™ uses the contact time at peak flow to calculate
the contact tank volume (Hydromantis, 2014).
— EPA's Wastewater Technology Fact Sheet - Dechlorination
recommends dechlorination contact times of one to five minutes to
react with free chlorine and inorganic chloramines (U.S. EPA,
2000). ERG selected five minutes to ensure adequate
dechlorination prior to discharge.
• Revised the CAPDETWorks™ input chemical dose to 3.75 mg/L to
reflect the sodium bisulfite solution dose:
— CAPDETWorks™ uses the chemical dose to size the chemical
feed storage building (Hydromantis, 2014).
— ERG selected the input chlorine dose for each wastewater
treatment configuration to achieve approximately 1 mg/L residual
chlorine. Specifically, for the chlorination unit process, ERG used
10 mg/L for Levels 1, 2-1, and 2-2; 8 mg/L for levels 3-1, 3-2, 4-1,
and 4-2; and 5 mg/L for Levels 5-1 and 5-2 (see Appendix E.1.8).
— EPA's Wastewater Technology Fact Sheet - Dechlorination
indicates that, on a mass basis, 1.46 parts of sodium bisulfite is
required to dechlorinate 1.0 parts of residual chlorine (U.S. EPA,
2000), which ERG rounded to 1.5 parts of sodium bisulfite.
Assuming a 40% by weight sodium bisulfide in solution results in
a sodium bisulfite dose of 3.75 mg/L, as presented in Equation E-l.
3.75 NaHS03 40% Solution 1.5 NaHSCb 100% Solution x 100%NaHS03 Solut'°n
\L J \L J 40% NaHSOs Solution
Equation E-l
EP-C-I6-QQ3; WA 2^37
E-10
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Sodium Bisulfite Liquid Feed System
• See Table E-l for calculation of sodium bisulfite liquid feed rates for each
wastewater treatment configuration.
• For sodium bisulfite liquid feed rates less than 100 gph, purchase cost of
$5,000, plus $300 for transport, in 2011 $, based on telephone contact with
EnPro Technologies (ERG, 201 lb). Escalated to 2014 $ using RSMeans
Construction Cost Index and the calculation presented in Section 3.2.1
(RSMeans, 2017).
• Used the installation factor of 0.3 from CAPDETWorks™ for the
installation of the dechlorination system to account for installation and
other costs such as electrical, piping, painting, etc. associated with the
sodium bisulfite system (Hydromatis, 2014).
Total capital costs were estimated by applying the CAPDETWorks™ direct and
indirect cost factors to the purchase costs, using the factors and methodology
described in Section 3.3 of this report.
-------
Appendix E: Detailed Cost Methodology
Table E-l. Sodium Bisulfite Liquid Feed Rate Calculation
1 v\ el
NiillSO.iKiilo
(»|)h) =
Sodium liisull'ile
Dose
x (>r;im lo
Milli^i'iini
l-;iclor<«i/m»)
x NiillSO.i Dose
l-iielor (ciilciiliiled in
liihle 1.-2)
x I'.sliiiiiiled
\\ iislewiiler
Trciilmcnl l-'low
( M(aD)
X 1.000.000
liiil/Miiiil
x D;i\ lo Hour
l-'iiclor idiiWhr)
Lc\ el 1
:.o
3.8
l.UL-3
l.~L-3
lu
1.0L O
0.04
Level 2-1
2.6
3.8
1.0E-3
1.7E-3
10
1.0E+6
0.04
Level 2-2
2.6
3.8
1.0E-3
1.7E-3
10
1.0E+6
0.04
Level 3-1
2.6
3.8
1.0E-3
1.7E-3
10
1.0E+6
0.04
Level 3-2
2.6
3.8
1.0E-3
1.7E-3
10
1.0E+6
0.04
Level 4-1
2.6
3.8
1.0E-3
1.7E-3
10
1.0E+6
0.04
Level 4-2
2.6
3.8
1.0E-3
1.7E-3
10
1.0E+6
0.04
Level 5-1
4.3
7.5
1.0E-3
1.7E-3
8.2
1.0E+6
0.04
Level 5-2
4.4
7.5
1.0E-3
1.7E-3
8.3
1.0E+6
0.04
Table E-2. Sodium Bisulfite Dose Factor Calculation
NiillSO.i Dose
l";ic(or =
1
/ (NiillSOJ ('oiiiTiili'iiliou ("i.i
x NiillSOJ lk'iisi(\ (k»/l.)
X 1.000 »/k»)
0.00168919
1
0.4
1.48
1000
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E-12
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Appendix E: Detailed Cost Methodology
E.3 Annual Costs
1. Operating Labor, Maintenance Labor, Materials and Supplies13
• Costed in 2014 $ using the CAPDETWorks™ chlorination unit process to
simulate dechlorination rather than chlorination.
• Revised the CAPDETWorks™ input contact time at peak flow to 5
minutes and chemical dose to 3.75 mg/L to reflect the dechlorination unit
contact time and dose (see justification in the Capital Cost section item
#1).
2. Energy
• One 0.5 HP feed system pump operated continuously for a calculated
annual electrical requirement of approximately 6,500 kWh/yr (ERG,
2011b).
• Using the CAPDETWorks™ energy rate of $0.10/kWh (2014 $)
(Hydromantis, 2014), total energy costs are approximately $650/yr.
3. Sodium Bisulfite
• Calculated using:
— Dosage rate of:
o 1.5 mg/L for Levels 1, 2-1, 2-2, 3-1, 3-2, 4-1, and 4-2 (see
justification in the Capital Cost section #1)
o 3.0 mg/L for Levels 5-1 and 5-2 to also account for the
chemicals required for RO pretreatment.14
— Effluent flow rate from the chlorination unit process for each
wastewater treatment configuration modeled in CAPDETWorks™.
• Assumed a 40% by weight sodium bisulfide in solution.
• Chemical cost of $344/ton of 40% sodium bisulfide solution in 2010 $
(ERG, 2014). This cost includes freight and assumes the chemical will be
delivered in drums or totes. Escalated to 2014 $ using RSMeans
Construction Cost Index (RSMeans, 2017.
E.4 Methanol Addition
Listed below are the capital cost elements included for dechlorination using sodium
bisulfite (NaHSOs), with a general description of the basis of estimate, followed by the O&M
cost elements and the basis of estimate.
13 Materials and supplies include materials and replacement parts required to keep the facilities in proper operating
conditions.
14 The RO system requires 1 mg/L chlorine pretreatment and a corresponding sodium bisulfite dechlorination. ERG
assumed the majority of the 1 mg/L chlorine would remain as chlorine residual. Therefore, the dechlorination
sodium bisulfite dose is 1.5 mg/L neat. Capital costs for the RO pretreatment sodium bisulfite system are included in
Appendix E.5.
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E-13
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Appendix E: Detailed Cost Methodology
Capital Costs
1. Methanol Storage Tank, Feed Pump, Control System, and Miscellaneous Items
(e.g., piping).
Costed in 2014 $ using the CAPDETWorks™ denitrification - attached growth
(i.e., denitrification filter) unit process that includes methanol addition. Selected
unit process input values to match the required nitrate reduction and used only the
output associated with the methanol system.
• Revised the CAPDETWorks™ influent wastewater average and minimum
flow rates to 10.1 MGD and maximum flow rate to 20.1 MGD to match
the influent flow rates for the 4-stage Bardenpho. CAPDETWorks™ uses
the influent wastewater flow rates to calculate the methanol system capital
cost (Hydromantis, 2014).
• Revised the CAPDETWorks™ influent nitrate concentration to 8.24 mg/L
to match the effluent from the 4-stage Bardenpho and the denitrification -
attached growth input allowable effluent nitrate to 1.95 mg/L to match the
necessary effluent nitrate concentration to achieve 3 mg/L total nitrogen
(TKN effluent is 1.05 mg/L) for Level 4-2, MBR. CAPDETWorks™ uses
the difference between the influent and allowable effluent nitrate
concentration to calculate the methanol feed rate, which is used to
calculate the methanol system capital cost (Hydromantis, 2014).
2. Methanol feed system cost (2014 $) from the CAPDETWorks™ output were
added to the 4-stage Bardenpho capital costs for the Level 4-2, MBR.
3. Total capital costs for the 4-stage Bardenpho were estimated by applying the
CAPDETWorks™ direct and indirect cost factors to the purchase costs, using the
factors and methodology described in Section 3.3 of this report.
Annual Costs
1. Operating Labor, Maintenance Labor, Materials and Supplies15, and Energy
• CAPDETWorks™ does not calculate costs for operating labor,
maintenance labor, materials and supplies, and energy for the methanol
feed system separately from the denitrification - attached growth unit
process. As a result, assumed the 4-stage Bardenpho operating labor,
maintenance labor, materials and supplies, and energy include costs for the
methanol feed system.
2. Methanol
• CAPDETWorks™ calculates the methanol cost based on the influent
nitrate and allowable effluent nitrate concentrations, as discussed in the
15 Materials and supplies include materials and replacement parts required to keep the facilities in proper operating
conditions.
KP-C-16-003; WA 2^37
E-14
-------
Appendix E: Detailed Cost Methodology
Capital Costs section above. Used the default methanol cost of $0.60/lb
from CAPDETWorks™
E.5 Ultrafiltration
Listed below are the capital cost elements included for ultrafiltration, with a general
description of the basis of estimate, followed by the O&M cost elements and the basis of
estimate. Table E-3 and Table E-4 summarize the capital and O&M cost calculations,
respectively.
Capital Costs
1. Membrane Filtration System - cost basis obtained from email contacts with
Evoqua Water Technologies LLC, 2015 (ERG, 2015a). Escalated to 2014 $ using
RSMeans Construction Cost Index (RSMeans, 2017). For a 9 MGD system for
this project16, purchase costs for membrane equipment and appurtenances are
approximately $3.7 million. Total capital costs were estimated by applying the
CAPDETWorks™ installation factor, and direct and indirect cost factors, to the
purchase costs, after incorporating the purchase costs into the CAPDETWorks™
outputs.
2. Membrane Filtration Building - using equipment dimensions provided by Evoqua
(ERG, 2015a), calculated a required building footprint of 8,040 square feet to
house the system. Using the CAPDETWorks™ building unit cost of $110/square
foot, calculated a total capital building cost of approximately $880,000.
Operating and Maintenance Costs
1. Operating Labor - transferred the operating labor costs from reverse osmosis
(RO) (see Appendix E.6).
2. Maintenance Labor - transferred the operating labor costs from RO (see
Appendix E.6).
3. Materials - membrane replacement cost of $1,650 per membrane times an
estimated 768 membranes for a 9 MGD system based on Evoqua (ERG, 2015a).
Assumed membranes have a 7-year life based on Evoqua (ERG, 2015a).
Escalated to 2014 $ using RSMeans Construction Cost Index (RSMeans, 2017).
Calculated materials costs of approximately $240,000/yr.
4. Chemicals - membrane cleaning chemical costs estimated using chemical usage
rates and costs per Evoqua (ERG, 2015a) and a $0.03/lb freight cost from
FreightCenter.com (ERG, 201 la), which were escalated to 2014 $ using
RSMeans Construction Cost Index (RSMeans, 2017), resulting in a total annual
chemicals cost of approximately $91,000/yr. Cleaning chemicals include citric
acid, sodium hypochlorite, sulfuric acid, sodium hydroxide, and sodium bisulfite.
16 Based on side stream treatment of 90 percent of the 10 MGD flow for Level 5-1 5-Stage Bardenpho with
Sidestream Reverse Osmosis.
KP-C-16-003; WA 2^37
E-15
-------
Appendix E: Detailed Cost Methodology
5. Energy - energy usage equal to the average of estimates provided by two sources:
• Evoqua (ERG, 2015a) estimated energy usage of 0.5 kWh/kgal
• WateReuse Research Foundation, 2014 estimated energy usage ranging from
0.75 to 1.1 kWh/kgal (average of 0.925 kWh/kgal)
Used the average of the average estimated energy usage from these two sources,
0.7125kWh/kgal (average of 0.5 kWh/kgal and 0.925 kWh/kgal). For a 9 MGD
system, and using the CAPDETWorks™ energy rate of $0.10/kWh (2014 $), total
annual energy costs are approximately $230,000.
KP-C-16-003; WA 2^37
E-16
-------
Appendix E: Detailed Cost Methodology
Table E-3. Ultrafiltration Capital Costs
l'!(|iii|>iiK'iu
Chsi lii-iii
Si/.i- iii-
Nii in Ikt
I nils
I nil Chsi
l nhil ( iisl
^ i-;i r
2014 PlIITll.lM-d ('iisl
Tnl.ll ( ;i|)il:il (iisl
Siiuru-
Ultrafiltration
9
MGD
$3,750,000
2015
$3,717,344
Evoqua (ERG, 2015a).
Ultrafiltration
Building
8,040
sq. foot
$110
$884,400
2014
$884,400
Evoqua, 2015; building unit
cost from CAPDETWorks™.
Table E-4. Ultrafiltration Operating and Maintenance Costs
()|K-r;ilin
-------
Appendix E: Detailed Cost Methodology
Table E-5. Ultrafiltration Operating and Maintenance Costs
Mi-ml>r;iiu- (li';min^
('lu-mk';ils
I (»:il/\ n
( list (S/»;il)
Allllll;il ('lu-lllk;ils Cusl (S/\ I )
Si ill I'll'
50% Citric Acid
4,551
$10.41
$47,369
Evoqua (ERG, 2015a); freight per FreightCenter.com
(ERG, 2011a).
50% Sulfuric Acid
2,891
$4.56
$13,183
Evoqua (ERG, 2015a); freight per FreightCenter.com
(ERG, 2011a).
12.5% Sodium
Hypochlorite
2,997
$0.89
$2,674
Evoqua (ERG, 2015a); freight per FreightCenter.com
(ERG, 2011a).
25%) Sodium Hydroxide
10,366
$2.43
$25,176
Evoqua (ERG, 2015a) (multiplied usage by 2 as usage
data based on 50% solution and cost data based on 25%o
solution); freight per FreightCenter.com (ERG, 201 la).
12.5%o Sodium Bisulfite
1,223
$2.43
$2,970
Evoqua (ERG, 2015a); freight per FreightCenter.com
(ERG, 2011a).
Table E-6. Ultrafiltration Operating and Maintenance Costs
I'".IUT»\
R;iU- (k\\ h/d;i\)
Aiiihi;iI I!iut»\ (k\\h/>n
I!iut»\ Kiik' (S/k\\ 111
Amiiiiil Cusl
(S/\ I )
Si hi in-
Ultrafiltration
6,413
2,340,563
$0.10
$234,056
Evoqua (ERG, 2015a);
WateReuse, 2014; and
CAPDETWorks™.
KP-C-16-003; WA 2^37
E-18
-------
Appendix E: Detailed Cost Methodology
E.6 Reverse Osmosis (RO)
Listed below are the capital cost elements included for RO, with a general description of
the basis of estimate, followed by the O&M cost elements and the basis of estimate. Table E-7
and Table E-8 summarize the capital cost calculations for the 90 and 85 percent flow options,
respectively (Levels 5-1 and 5-2), while Table E-9 and Table E-12 summarize the O&M cost
calculations for the 90 and 85 percent flow options, respectively (Levels 5-1 and 5-2).
Capital Costs
1. RO System - cost basis obtained from telephone contacts with Wigen Water
Technologies, 2015 (ERG, 2015b). Prepared a cost curve based on purchase costs
provided for 2.5, 5, and 10 MGD systems (see Figure E-l).
$5,000,000
$4,500,000
$4,000,000
$3,500,000
3 $3,000,000
o
vv $2,500,000
% $2,000,000
u
$1,500,000
$1,000,000
$500,000
$0
v = -5333.3x2 + 500000X + 33333 -
*—1
"
cc
j1'
--
m
4 6 8
Flow (MGD)
10
12
Figure E-l. RO Purchase Cost Curve
2.
Escalated to 2014 $ using RSMeans Construction Cost Index (RSMeans, 2017).
For a 9 MGD and 8.5 MGD system for this project17, purchase costs for
membrane equipment and appurtenances are approximately $4.4 million and $4.2
million, respectively. Total capital costs were estimated by applying the
CAPDETWorks™ installation factor, and direct and indirect cost factors, to the
purchase costs, after incorporating the purchase costs into the CAPDETWorks™
outputs.
RO Building - using equipment dimensions provided by Wigen (ERG, 2015b),
calculated a required building footprint of 4,960 square feet to house the system.
17 Based on side stream treatment of 85% and 90% of the 10 MGD flow for Level 5-1 5-Stage Bardenpho with
Sidestream Reverse Osmosis and Level 5-2 5-Stage Bardenpho Membrane Bioreactor with Sidestream Reverse
Osmosis, respectively.
EP-C'-16-003: WA 2-37
E-19
-------
Appendix E: Detailed Cost Methodology
Using the CAPDETWorks™ building unit cost of $110/square foot, calculated a
total capital building cost of approximately $550,000.
3. Chlorine Feed System - assumed a single, shared chlorine feed system for the RO
biofouling control pretreatment and final wastewater disinfection. Costs for the
shared chlorine feed system were estimated as part of the CAPDETWorks™
chlorine wastewater disinfection module.
4. Dechlorination and Antiscalant Feed Systems - purchase cost of $5,000, plus
$300 for transport, for each feed system based on telephone contact with
EnProTechnologies (ERG, 201 lb). Escalated to 2014 $ Using RSMeans
Construction Cost Index (RSMeans, 2017), resulting in a 2014 purchase cost of
approximately $5,900 for each of these two systems. Total capital costs were
estimated by applying the CAPDETWorks™ installation factor, and direct and
indirect cost factors, to the purchase costs, after incorporating the purchase costs
into the CAPDETWorks™ outputs.
5. Brine Surge Sump - estimated an in-ground concrete brine collection sump
volume based on an assumed 60-minute residence time (best professional
judgement) and a RO rejection rate of 20 percent based on telephone contacts
with Wigen (ERG, 2015b). Calculated a total capital cost of approximately
$190,000 for the 90% side stream treatment option, and approximately $180,000
for the 85% side stream treatment option, using a concrete basin cost curve
developed using RSMeans Building Construction Cost Data (see Figure E-2).
Escalated from $2010 to 2014 $ using RSMeans Construction Cost Index
(RSMeans, 2017).
Sump Volume (Gallons)
Figure E-2. Brine Surge Sump Total Capital Cost Curve
EP-C'-16-003: WA 2-37
E-20
-------
Appendix E: Detailed Cost Methodology
Operating and Maintenance Costs
1. Operating Labor - One labor hour per day based on Wigen (ERG, 2015b) and
CAPDETWorks™ operator labor rate of $51.50/hour (2014 $) for a total
operating labor cost of approximately $19,000/yr.
2. Maintenance Labor - One labor hour per day based on best professional
judgement that maintenance labor requirements would be similar to, and not
greater than, operating labor requirements, and sufficient for maintenance
activities such as lubrication, troubleshooting, and installing replacement parts.
Used the CAPDETWorks™ operator labor rate of $51.50/hour (2014 $), for a
total annual maintenance labor cost of approximately $19,000/yr.
3. Materials - membrane replacement cost of $450 per membrane times an
estimated 2,000 membranes for a 10 MGD system based on Wigen (ERG,
2015b), scaled to 9 MGD and 8.5 MGD systems for this project. Assumed
membranes has a 4-year life based on Wigen (ERG, 2015b). Escalated to 2014 $
using RSMeans Construction Cost Index (RSMeans, 2017). Calculated materials
costs of approximately $162,000/yr for the 90% side stream treatment option, and
approximately $150,000/yr for the 85% side stream treatment option.
4. Antiscalant Chemicals - calculated using dosage rate of 3 mg/L of Vitec 3000 per
Wigen (ERG, 2015b). Vitec 3000 chemical cost of approximately $1,300/500 lb
provided by Water Surplus, 2015 and a $0.03/lb freight cost from
FreightCenter.com (ERG, 201 la), for a total antiscalant chemicals cost of
approximately $220,000/yr and $200,000/yr for the 90% and 85% side stream
treatment options, respectively.
5. Membrane Cleaning Chemicals - per Wigen (ERG, 2015b), two cleaning
chemicals are each 4,000 lb/yr for a 2.5 MGD system at a cost of $5/lb. Scaled to
9 MGD and 8.5 MGD for this project and added a $0.03/lb freight cost from
FreightCenter.com (ERG, 201 la), for a total membrane cleaning chemicals cost
of approximately $145,000/yr and $137,000/yr for the 90% and 85% side stream
treatment options, respectively.
6. Chlorine and Sodium Bisulfite Pretreatment Chemicals - modified the
CAPDETWorks™ chlorine wastewater disinfection module, and the
supplemental dechlorination module developed for this project, to incorporate the
additional chemical requirements associated with RO pretreatment. Assumed a 1
mg/L chlorine dosage rate per Wigen (ERG, 2015b) and a corresponding
dechlorination dosage rate.
7. RO System Energy - energy usage equal to the average of estimates provided by
two sources:
• Wigen (ERG, 2015b) estimated energy usage ranging from 3,000 to 6,000
kWh/day for a 2.5 MGD system (average of 4,500 kWh for a 2.5 MGD
system, or 1.8 kWh/kgal)
• WateReuse Research Foundation, 2014 estimated energy usage ranging from
1.9 to 2.3 kWh/kgal (average of 2.1 kWh/kgal)
KP-C-16-003; WA 2^37
E-21
-------
Appendix E: Detailed Cost Methodology
Used the average of the average estimated energy usage from these two sources,
1.95kWh/kgal (average of 1.8 kWh/kgal and 2.1 kWh/kgal). For a 9 MGD
system, and using the CAPDETWorks™ energy rate of $0.10/kWh (2014 $), total
annual energy costs are approximately $640,000/yr and $600,000/yr for the 90%
and 85% side stream treatment options, respectively.
8. Dechlorination and Antiscalant Feed System Energy - Two 0.5 HP feed system
pumps operated continuously for a calculated annual electrical requirement of
approximately 6,500 kWh/yr. Using the CAPDETWorks™ energy rate of
$0.10/kWh (2014 $), total energy costs are approximately $650/yr.
KP-C-16-003; WA 2^37
E-22
-------
Appendix E: Detailed Cost Methodology
Table E-7. RO Capital Costs, 90 Percent of Flow
l'l(|iii|>iiK'iil Cusl lii-iii
Si/.i- or
IlllllllKT
I nils
I nil Cusl
Tnl.il Cusl
^ i ;i r
2014 Punhiisi-il
( IISl
Tiihil ( ;i|)il;il
Cusl
Si hiriv
RO System
9
MGD
$4,460,136
2015
$4,421,296
Wigen (ERG, 2015b).
RO System Building
4,960
sq. foot
$110
$545,600
2014
$545,600
Wigen (ERG, 2015b); building
unit cost from
CAPDETWorks™.
Chlorination Feed System
$0
$0
Dechlorination Feed
System
1
Each
$5,300
$5,300
2010
$5,918
EnPro (ERG, 2011b).
Anti-Scale Feed System
1
Each
$5,300
$5,300
2010
$5,918
EnPro (ERG, 2011b).
Brine Surge Sump
75,000
gallons
$166,005
2010
$185,364
RSMeans Building
Construction Cost Data; RO
rejection rate from Wigen
(ERG, 2015b).
Table E-8. RO Capital Costs, 85 Percent of Flow
I'l(|lli|)llll'lll ClISl Ill-Ill
Si/.i- fir
niinihi'i'
I nils
I nil
ClISl
Tiihil Cusl
^ i ;i r
2014 Piirihiisi-d
Cusl
Tiihil C;i|)iliil
Cusl
Si ill I'll-
RO System
8.5
MGD
$4,214,802
2015
$4,178,098
Wigen (ERG, 2015b).
RO System Building
4,960
sq. foot
$110
$545,600
2014
$545,600
Wigen (ERG, 2015b); building
unit cost from
CAPDETWorks™.
Chlorination Feed System
$0
$0
Dechlorination Feed
System
1
Each
$5,300
$5,300
2010
$5,918
EnPro (ERG, 2011b).
Anti-Scale Feed System
1
Each
$5,300
$5,300
2010
$5,918
EnPro (ERG, 2011b).
Brine Surge Sump
70,833
gallons
$160,650
2010
$179,385
RSMeans Building
Construction Cost Data; RO
rejection rate from Wigen
(ERG, 2015b).
KP-C-16-003; WA 2^37
E-23
-------
Appendix E: Detailed Cost Methodology
Table E-9. RO Operating and Maintenance Costs, 90 Percent of Flow
()|KT;ilinor R:ik- (S/lir)
I);i\s/\ r
Annii.il \l;iiiili'ii;uui' l.;il>nr
Cosl (S/\ r)
Si HI I'l l'
RO System
1
$51.50
365
$18,798
13esl Professional Judgement and
C'Al'l)l 1 \\oils v
M;ik'l'i;ils
Allllll;il
M:ik'i'i;ils Ciisl
(S/>r)
Shu nv
RO System
$162,044
Wigen (ERG, 2015b).
Table E-10. RO Operating and Maintenance Costs, 90 Percent of Flow
(Iu'lllii';ils
I)om- R;ik-
(ll)s/^;il)
Tnl.ll I'll>\\ («i;il/\
Aniiiiiil Anli-
Si ;ili- <. In-ill ii;ils
(llis/\ r)
Ciisl
linn
Pretreatment
Anti-Scale
0.00002
3,285,000,000
82,063
$2.64
$216,317
Dose per Wigen (ERG,
2015b); cost per Water
Surplus, 2015; freight per
FreightCenter.com (ERG,
2011a).
Annual Vitec 3000
Consumption: 91,181 lb/yr
Annual Citric Acid
Consumption: 16,000 lb/yr
Membrane
Cleaning
0.00001
3,285,000,000
28,800
$5.03
$144,864
Wigen (ERG, 2015b); freight
perFreightCenter.com (ERG,
2011a).
Annual Sodium Hypochlorite
Consumption: 16,000 lb/yr
Pretreatment
Chlorine
$0.00
Incorporated into wastewater
disinfection module.
Pretreatment
Sodium Bisulfite
$0.00
Incorporated into wastewater
dechlorination module.
KP-C-16-003; WA 2^37
E-24
-------
Appendix E: Detailed Cost Methodology
Table E-ll. RO Operating and Maintenance Costs, 90 Percent of Flow
R;iU- (k\\ h/d;i\)
Anniiiil ITi'iliii;il (k\Mi/\r)
I!iut»\ Kuli- (S/k\\ In
Amiiiiil I!iut»\ Chsi (S/\n
Si ill I'll'
RO System
17,550
6,405,750
$0.10
$640,575
Wigen (ERG, 2015b);
WateReuse, 2014;
CAPDETWorks™.
Chemical Feed
Systems
18
6,531
$0.10
$653
EnPro (ERG, 2011b);
CAPDETWorks™.
Table E-12. RO Operating and Maintenance Costs, 85 Percent of Flow
()|K'i';ilinnr
l.iilmr (hrs/d;i\)
l.;il)nr Kiili' (S/lir)
l);i\s/\ r
Aiiniuil ()|)i r;ilin^ L;il)nr Cusi
or (hrs/d;i\)
l.;il>nr R;ili- (S/lir)
I);i\s/\ r
Anniiiil Muink niinii' l.;il)nr Cusi
(S/M)
Si hi in-
RO System
1
$51.50
365
$ 18.798
13esl Professional Judgement
and CAPDETWorks™
Miiii-riiils
Anniiiil Miiii-riiils
Cusi (S/\r)
Si ill I'll'
RO System
$153,041
Wigen (ERG, 2015b).
KP-C-16-003; WA 2^37
E-25
-------
Appendix E: Detailed Cost Methodology
Table E-13. RO Operating and Maintenance Costs, 85 Percent of Flow
Allllll;il
Diisi- K;ik-
Tnl.il Mow
Amiiiiil Ami-Sink-
Cosl
( Ill-Illk;ils
(lumii;ils
(ll)s/»;il)
r)
(lii'mii;ils (ll>s/\ r)
(S/ll))
Ciisl (S/\ r)
Si ill I'll'
Clu'mk';il ( iiiisiiinpliiiii
Pretreatment
Anti-Scale
0.00002
3,102,500,000
77,504
$2.64
$204,299
Dose per Wigen (ERG,
2015b); cost per Water
Surplus, 2015; freight per
FreightCenter.com (ERG,
2011a).
Annual Vitec 3000
Consumption: 91,181 lb/yr
Annual Citric Acid
Consumption: 16,000 lb/yr
Membrane
Cleaning
0.00001
3,102,500,000
27,200
$5.03
$136,816
Wigen (ERG, 2015b);
freight per
FreightCenter.com (ERG,
2011a).
Annual Sodium Hypochlorite
Consumption: 16,000 lb/yr
Pretreatment
Incorporated into
wastewater disinfection
Chlorine
$0.00
module.
Pretreatment
Sodium
Incorporated into
wastewater dechlorination
Bisulfite
$0.00
module.
Table E-14. RO Operating and Maintenance Costs, 85 Percent of Flow
l'".IUT»\
Riili- (k\\ h/d;i\)
Amiiiiil r.li'iirii;il (k\\h/\r)
I!iut»\ KsiIi- (S/k\Mi)
Amiiiiil I''.iut C'hsi
(S/\ I )
Sou nv
RO System
16,575
6,049,875
$0.10
$604,988
Wigen (ERG, 2015b);
WateReuse, 2014;
CAPDETWorks™.
Chemical Feed
Systems
18
6,531
$0.10
$653
EnPro (ERG, 2011b) and
CAPDETWorks™.
KP-C-16-003; WA 2^37
E-26
-------
Appendix E: Detailed Cost Methodology
E.7 Deep Well Injection
Listed below are the capital cost elements included for deep well injection, with a general
description of the basis of estimate, followed by the O&M cost elements and the basis of
estimate. Table E-15 and Table E-16 summarize the capital and O&M cost calculations,
respectively.
Capital Costs
1. Deep Injection Well - cost basis obtained from telephone contact with North Star
Disposal, Inc (U.S. EPA, 2012a). Drilling a new underground injection well costs
$3.5 million for a deep well, which was escalated to 2014 $ using RSMeans
Construction Cost Index (RSMeans, 2017), resulting in a 2014 total capital cost of
approximately $3.7 million.
2. Injection Pump/Electrical Building - estimated pump house dimensions (12'xl4')
based on best professional judgement to house the 3 pumps and control panel, as
informed by domestic wastewater deep well injection proposal prepared by the
Santa Clarita Valley Sanitation District, 201518. Using the CAPDETWorks™
building unit cost of $110/square foot, calculated a total capital building cost of
approximately $18,000.
3. Injection Well Pumps - cost basis of approximately $49,000 for a 786 gpm
multistate pump obtained from Water Surplus, 2015, which was escalated to 2014
$ using RSMeans Construction Cost Index (RSMeans, 2017). Assumed 2 pumps
in operation and 1 spare for a total purchase cost of approximately $140,000.
Total capital costs were estimated by applying the CAPDETWorks™ installation
factor, and direct and indirect cost factors, to the purchase costs, after
incorporating the purchase costs into the CAPDETWorks™ outputs.
4. Injection Well Pumps Freight - cost basis of approximately $1,750 per flatbed
truckload to transport all three pumps (total of 10 tons) obtained from Siemens
(ERG, 201 lc), which we escalated to 2014 $ using RSMeans Construction Cost
Index (RSMeans, 2017). Total capital costs were estimated by applying the
CAPDETWorks™ installation factor, and direct and indirect cost factors, to the
purchase costs, after incorporating the purchase costs into the CAPDETWorks™
outputs.
Operating and Maintenance Costs
1. Operating Labor - 0.5 labor hour per day based on best professional judgement to
inspect the pump motors and to record data, and CAPDETWorks™ operator labor
rate of $51.50/hour (2014 $), for a total annual operating labor cost of
approximately $9,400.
18 Santa Clarity Valley Sanitation District. 2015. Information Sheet - Deep Well Injection Site for Brine Disposal.
DOC #2970311. Accessed from http://www.lacsd.org/civicax/filebank/blobdload.aspx?blobid=9556.
KP-C-16-003; WA 2^37
E-27
-------
Appendix E: Detailed Cost Methodology
2. Maintenance Labor - 0.5 labor hour per day based on best professional judgement
that maintenance labor requirements would be similar to, and not greater than,
operating labor requirements, and sufficient for maintenance activities such as
lubrication, troubleshooting, and installing replacement parts. Used the
CAPDETWorks™ operator labor rate of $51.50/hour (2014 $), for a total annual
maintenance labor cost of approximately $9,400/yr.
3. Materials - calculated total annual maintenance materials cost as 2 percent of
injection well pump purchase cost based on CAPDETWorks™ methodology.
Calculated a maintenance materials cost of approximately $3,000/yr.
4. Energy - Two 350 HP injection well pumps operated continuously for a
calculated annual electrical requirement of approximately 4.5 million kWh/yr.
Using the CAPDETWorks™ energy rate of $0.10/kWh (2014 $), total energy
costs are approximately $460,000/yr.
KP-C-16-003; WA 2^37
E-28
-------
Appendix E: Detailed Cost Methodology
Table E-15. Deep Well Injection Capital Costs
l;.(|iii|>iiK'iil Cusi lii-iii
NuiiiIkt
I nils
I nil Cusi
TiHal Ciisl
^ i ;i r
2014 Cusi
Tiilal Capital
ClISl
l);il;i Siilini-
Deep Injection Well
1
Each
$3,500,000
$3,500,000
2012
$3,685,252
North Star Disposal (U.S.
EPA, 2012a).
Injection pump building to
house pumps and electrical
168
square feet
$110
$18,480
2014
$18,480
Best professional judgement;
building unit cost from
CAPDETWorks™.
Injection Well Pumps
3
Each
$48,730
$146,190
2015
$144,917
Water Surplus, 2015.
Injection Well Pumps
Freight
1
Flatbed
Truck
$1,750
$1,750
2011
$1,875
Siemens (ERG, 201 lc).
Table E-16. Deep Well Injection Operating and Maintenance Costs
()|KT;ilinr
Purchase)
Annual Mali-rials
Cost (S/\ I')
Suurcc
$144,917
2
$2,898
CAPDETWorks™.
Clu-miials
Diisi- kali-
(ll>s/<;al)
Tiilal I'll>\\
(li;illi>ns/\ r)
Annual Anli-Siali-
Clu-miials (llis/\ r)
( IISl (S/lh)
Annual Clu'iniials Cusi (S/\r)
No chemical requirements
I!iut»>
kali- (k\\ h/da\)
Annual l!li-iiriial
(k\\ h/\ r)
I!iut»> kali- (S/k\\ li)
Annual Kiut»>
Cusi (S/\ri
Sim nv
12,526
4,572,019
$0.10
$457,202
Water Surplus, 2015 and
CAPDETWorks™.
KP-C-16-003; WA 2^37
E-29
-------
Appendix E: Detailed Cost Methodology
E.8 CAPDETWorks™ Direct Cost Factor Development
See Companion PDF File.
KP-C-16-003; WA 2^37
E-30
-------
Appendix F: Detailed Air Emissions Methodology
APPENDIX F
DETAILED AIR EMISSIONS METHODOLOGY
KP-C-16-003; WA 2^37
-------
Appendix F: Detailed Air Emissions Methodology
Appendix F: Detailed Air Emissions Methodology
F.l Greenhouse Gas Analysis
This section details the calculations used to determine the process-level GHG emissions
from the wastewater treatment and sludge handling stages, from the effluent, and from landfilled
sludge. GHG emissions from background and upstream fuel and material processes already exist
within the LCI databases used, and while incorporated in the study results, are not discussed
here.
F. 1.1 Methane Emissions from Biological Treatment
The methodology for calculating CH4 emissions associated with the wastewater treatment
configurations evaluated as part of this study is generally based on the guidance provided in the
IPCC Guidelines for national inventories. CH4 emissions are estimated based on the amount of
organic material (i.e., BOD) entering the unit operations that may exhibit anaerobic activity, an
estimate of the theoretical maximum amount of methane that can be generated from the organic
material (B0), and a methane correction factor that reflects the ability of the treatment system to
achieve that theoretical maximum. In general, the IPCC does not estimate CH4 emissions from
well managed centralized aerobic treatment systems. However, there is acknowledgement that
some CH4 can be emitted from pockets of anaerobic activity, and more recent research suggests
that dissolved CH4 in the influent wastewater to the treatment system is emitted when the
wastewater is aerated.
For this analysis, some of the wastewater treatment configurations include anaerobic
zones within the treatment system. For these configurations, a methane correction factor (MCF)
was used. The methodological equation is:
CH4process = BOD (mg/L) x Flow (MGD) x 3.785 L/gal x 365.25 days/yr x lxlO"6 kg/mg x B0 x MCF
Equation F-l
where:
CH4 process — CH4 emissions from wastewater treatment process (kg CH4 /yr)
BOD = Concentration of BOD entering biological treatment process (mg/L)
Flow = Wastewater treatment flow entering biological treatment process (MGD)
Bo = maximum CH4 producing capacity, kg CH4/kg BOD
MCF = methane correction factor (fraction)
For this analysis, there was no relevant MCF provided in the IPCC guidance for
centralized aerobic treatment with the wastewater treatment configurations included in this study.
Instead, MCFs were developed based on GHG emission studies that were conducted at two U.S.
WWTPs. The first study (Czepiel, 1995) evaluated emissions associated with a conventional
activated sludge treatment plant, resulting in an MCF of 0.005, which was used for Level 1. The
second study (Daelman et al., 2013) evaluated emissions associated with a municipal treatment
KP-C-16-003; WA 2^37
F-l
-------
Appendix F: Detailed Air Emissions Methodology
plant with biological nutrient removal (specifically nitrification and denitrification), resulting in
an MCF of 0.05, which was used for all other levels of treatment. No other studies were available
and acceptable for use to allow differentiating CH4 emissions between Levels 2 through 5.
The annual emissions per system were than translated to emissions per m3 of wastewater
treated, using the following calculation and displayed in Table F-l.
CH4 Process Emissions (kg CFU/m3 wastewater) = CH4 process [10 MGD x 365 days/yr x
0.00378541 m3/gal]
Equation F-2
Table F-l. Methane Emissions from Biological Treatment
S\sU'ill
(onl'i;iur;ilinn
1 .c\ el
liiHiieiil li()l) lo
hioirciilmcnl.
niii/l.
Mow. M(,l)
MCI-"
( II4 I'm it led In
Process. kti
Cll4/>r
CII4 Process
l-'.missittus. kii
CI 14/111°' \\iis(c\\;i(er
1
l.oE+2
lu
5.0E-3
d.8E-i-3
5.0E-4
2-1
1.6E+2
10
0.05
6.6E+4
4.8E-3
2-2
1.6E+2
10
0.05
6.8E+4
4.9E-3
3-1
1.7E+2
10
0.05
7.1E+4
5.1E-3
3-2
1.7E+2
10
0.05
7.1E+4
5.1E-3
4-1
1.7E+2
10
0.05
7.1E+4
5.1E-3
4-2
1.6E+2
10
0.05
6.6E+4
4.8E-3
5-1
1.7E+2
10
0.05
7.1E+4
5.1E-3
5-2
1.7E+2
10
0.05
7.0E+4
5.1E-3
F.1.2 Nitrous Oxide Emissions from Biological Treatment
The methodology for calculating N2O emissions associated with wastewater treatment is
based on estimates of emissions reported in the literature. The guidance provided in the IPCC
Guidelines for national inventories does not provide a sufficient basis to distinguish N2O
emissions from varying types of wastewater treatment configurations, particularly related to
biological nutrient reduction. More recent research has highlighted the fact that emissions from
these systems can be highly variable based on operational conditions, specific treatment
configurations, and other factors (Chandran, 2012).
For this analysis, data collected from 12 WWTPs were reviewed to identify which
wastewater treatment configuration they may best represent (Chandran, 2012). Using the
emissions measured from these systems, an average emission factor (EF) was calculated and
applied to the modeled data for the nine system configurations. The methodological equation is:
N2Oprocess = TKN (mg/L) x Flow (MGD) x 3.785 L/gal x 365.25 days/yr x lxlO"6 kg/mg x EF% x
44/14
Equation F-3
KP-C-16-003; WA 2^37
F-2
-------
Appendix F: Detailed Air Emissions Methodology
where:
N2O process = N2O emissions from wastewater treatment process (kg N2O /yr)
TKN = Concentration of TKN entering biological treatment process (mg/L)
Flow = Wastewater treatment flow entering biological treatment process (MGD)
EF% = average measured % of TKN emitted as N2O, %
44/14 = molecular weight conversion of N to N2O
As displayed in Table F-2, the annual emissions per system were translated to emissions
per m3 of wastewater treated, using the following calculation.
N2O Process Emissions (kg N2O /m3 wastewater) = N2O process [10 MGD x 365 days/yr x
0.00378541 m3/gal]
Equation F-4
Table F-2. Nitrous Oxide Emissions from Biological Treatment
Sjslcm
Council r;ilioii
1 .c\ el
InI'liioiil TKN
1(1
l>ioirc;ilmcnl.
111 ii/1
How.
\i(;i)'
i:i-%.
1. milled
us VO
Soiiito of HI-"
I nil
Openilion
Biisis
VO
11 mi lied In
Process. k»
N :()/>r
VO Process
Emissions.
k» VO/in'
\\;islc\\;ilcr
1
43
10
0.035%
Czepiel
(1995)
conventional
activated
sludge
6.6E+2
4.8E-5
2-1
41
10
0.160%
Chandran
(2012)
MLE
2.9E+3
2.1E-4
2-2
43
10
0.020%
Chandran
(2012)
separate stage
BNR
3.9E+2
2.8E-5
3-1
42
10
0.425%
Chandran
(2012)
4-stage
Bardenpho
7.8E+3
5.7E-4
3-2
42
10
0.160%
Chandran
(2012)
MLE
3.0E+3
2.1E-4
4-1
43
10
0.425%
Chandran
(2012)
4-stage
Bardenpho
8.2E+3
5.9E-4
4-2
41
10
0.425%
Chandran
(2012)
4-stage
Bardenpho
7.7E+3
5.6E-4
5-1
42
10
0.425%
Chandran
(2012)
4-stage
Bardenpho
7.8E+3
5.7E-4
5-2
42
10
0.425%
Chandran
(2012)
4-stage
Bardenpho
7.7E+3
5.6E-4
a - Flow and influent TKN to biotreatment is based on CAPDETWorks™ modeling
F. 1.3 Methane Emissions due to Anaerobic Digestion
The methodology for calculating CH4 emissions associated with anaerobic sludge
digestion is based on the guidance provided in the IPCC Guidelines for national inventories. CH4
emissions from anaerobic digestion of sludge were estimated based on the amount of biogas
EP-C-I6-QQ3; WA 2^37
F-3
-------
Appendix F: Detailed Air Emissions Methodology
generated by the digester, an estimation of the biogas composition, and an estimation of the
amount of CH4 destroyed through flaring.
CH4 emissions from anaerobic digesters were estimated by multiplying the amount of
biogas generated by wastewater sludge treated in anaerobic digesters by the proportion of CH4 in
digester biogas (0.65), the density of CH4 (662 g CHVm3 CH4), and the destruction efficiency
associated with burning the biogas in an energy/thermal device (0.99). For this analysis, ERG is
assuming the biogas is flared, and not recovered for energy use. The methodological equation is:
CH4 digester — Biogas Flow x conversion to m3 x (525960 min/year) x (FRAC_CH4) x (density of CH4) x
(1-DE) x 1/10A3
Equation F-5
where:
CH4 digester — CH4 emissions from anaerobic digestion (kg CH4 /yr)
Biogas Flow = Cubic feet of digester gas produced by digester (ftVmin)
conversion to m3 = Conversion factor, ft3 to m3 (0.0283)
FRAC CH4 = Proportion CH4 in biogas (0.65)
density of CH4 = 662 (g CFU/m3 CH4)
DE = CH4 destruction efficiency from flaring (0.99 for enclosed flares)
1/10A3 = Conversion factor, g to kg
As shown in Table F-3 the annual emissions per system were translated to emissions per
m3 of wastewater treated, using the following calculation.
CH4 Digester Emissions (kg CFU/m3 wastewater) = CH4 digester [10 MGD x 365 days/yr x
0.00378541 m3/gal]
Equation F-6
Table F-3. Methane Emissions due to Anaerobic Digestion
S\slem
(oiiri"iir;iiion
Let el
liio^iis l- low. ITVmiir'
( II4 (>ener;ileri In
Digester, kg
< IL/.m-
( II41'milted In
Diiiesler. kii (IL/vr
( IL Di^esler l-'missittus.
kii CII4/111"' wastewater
1
1.1E+2
6.9E+5
6.9E+3
5.0E-4
2-1
88
5.6E+5
5.6E+3
4.1E-4
2-2
1.2E+2
7.6E+5
7.6E+3
5.5E-4
3-1
85
5.4E+5
5.4E+3
3.9E-4
3-2
85
5.4E+5
5.4E+3
3.9E-4
4-1
85
5.4E+5
5.4E+3
3.9E-4
4-2
87
5.6E+5
5.6E+3
4.1E-4
5-1
85
5.4E+5
5.4E+3
3.9E-4
5-2
82
5.2E+5
5.2E+3
3.8E-4
a - Biogas flow is based on CAPDETWorks™ modeling.
KP-C-16-003: WA 2-37 F-4
-------
Appendix F: Detailed Air Emissions Methodology
Air emissions other than CH4 associated with flaring the digester biogas are covered at
the end of this Appendix.
F. 1.4 Nitrous Oxide Emissions from Effluent Discharged to Receiving Waters
The methodology for calculating nitrous oxide emissions associated with effluent
discharge is based on the guidance provided in the IPCC Guidelines for national inventories.
N2O emissions from domestic wastewater (wastewater treatment) were estimated based on the
amount of nitrogen discharged to aquatic environments from each of the system configurations,
which accounts for nitrogen removed with sewage sludge.
N20effluent = Neffluent x Flow x 3.785 L/gal x 365.25 days/yr x lxlO"6 kg/mg x EF3 x 44/28
Equation F-7
where:
N20effluent
Neffluent
Flow
EF3
44/28
N2O emissions from wastewater effluent discharged to aquatic
environments (kg N20/yr)
N in wastewater discharged to receiving stream, mg/L
Effluent flow, MGD
Emission factor (0.005 kg N2O -N/kg sewage-N produced)
Molecular weight ratio of N2O to N2
As presented in Table F-4, the annual emissions per system were then translated to
emissions per m3 of wastewater treated, using the following calculation.
N2O Effluent Emissions (kg N20/m3 wastewater) = N20effluent ^ [10 MGD x 365 days/yr x
0.00378541 m /gal]
Equation F-8
Table F-4. Nitrous Oxide Emissions from Effluent Discharged to Receiving Waters
S\ stem ( (iiilliiii nil ion
l.e\el
IHTIiicnl l oiiil \i(m»en.
mii/l
VO r.lTliicnl l-'niissittus.
k» \ :()/>r
VO I'llTluciil Km issittus.
k» VO/nr' wiislowiiloi'
1
30
3.2E+3
2.3E-4
2-1
8.0
8.7E+2
6.3E-5
2-2
7.8
8.4E+2
6.1E-5
3-1
6.0
6.5E+2
4.7E-5
3-2
6.0
6.5E+2
4.7E-5
4-1
3.0
3.2E+2
2.4E-5
4-2
3.0
3.3E+2
2.4E-5
5-1
0.78
69
5.0E-6
5-2
1.9
1.7E+2
1.3E-5
a - Effluent nitrogen is based on CAPDETWorks™ modeling and calculated as TKN + nitrate + nitrite.
EP-C-I6-QQ3; WA 2^37
F-5
-------
Appendix F: Detailed Air Emissions Methodology
F. 1.5 Methane Emissions and Energy Recovery from Sludge Disposal in Landfills
The methodology for calculating CH4 emissions associated with landfill disposal are
based on the general presumption that the portion of the landfill receiving anaerobic digester
sludge operates as a "bioreactor landfill" due to the high BOD and water loading. As such, the
anaerobic digestion process will reach steady state quickly. In addition, the anaerobic conversion
of BOD to CH4 will be very similar between anaerobic sludge digesters and anaerobic bioreactor
landfills. As such, the ratio of CH4 evolution to BOD removal in an anaerobic digester will also
be applicable to sewage sludge degradation in anaerobic landfills. ERG calculated an emission
factor for landfill emissions based on the conversion of organic material to CH4, as seen in the
anaerobic sludge digester. Using modeled outputs from Level 1, ERG calculated an emission
factor of 0.61 kg CH4 emitted per kg BOD added using the following equation:
CH4EF LANDFILL = Digester CH4 Generated x [(Digester BOD Inlet-Digester BOD Outlet) x
365.25 days/yr]
Equation F-9
where:
CH4EF landfill — CH4 emission factor for landfills receiving municipal sludge
(kg CH4/kg BOD removed)
Digester CH4 Generated = CH4 emissions generated in anaerobic sludge digester for
Level 1 system, kg CFU/yr
Digester BOD Inlet = BOD entering the digester, kg/day
Digester BOD Outlet = BOD exiting the digester, kg/day
CH4 emissions from domestic wastewater (wastewater treatment) were estimated based
on the amount of BOD transferred to the landfill in digested sludge.
CH4 LANDFILL — Sludge Volume * BOD x 3.785 L/gal x 365.25 days/yr x lxlO"6 kg/mg x CH4EF LANDFILL
Equation F-10
where:
CH4 LANDFILL
Sludge Volume
BOD
CH4EF LANDFILL
= CH4 emissions from landfilled sludge (kg CFU/yr)
= Volume of sludge transferred to landfill, MGD
= BOD concentration in digested sludge, mg/L
= CH4 emission factor for landfills receiving municipal sludge (kg
CH4/kg BOD)
As displayed in Table F-5, the annual emissions per system were then translated per m3
of wastewater treated, using the following calculation. These values assume no capture of
landfill gas.
KP-C-16-001
F-6
-------
Appendix F: Detailed Air Emissions Methodology
CH4 Landfill Emissions (kg CH4/m3 wastewater) = CH4landfill ^ [10 MGD x 365 days/yr x 0.00378541
m3/gal]
Equation F-l 1
Table F-5. Raw Methane Emissions from Sludge Disposal in Landfills
S\s(em
('onri"iir;iiiun
Let el
Sludge Volume.
M(,l)
Sludge li()l).
111 Si/L
( II4 LiimHill
l-'missituis. kg ('II4A1'
Kiiw ( ll4 LiiiKMill
( missions. kg ( ll4 /in'
\\;isle\\;Mer
1
0.02
7.2E+3
1.2E+5
8.9E-3
2-1
0.02
7.0E+3
1.0E+5
7.3E-3
2-2
0.03
5.4E+3
1.4E+5
9.8E-3
3-1
0.02
5.6E+3
9.7E+4
7.0E-3
3-2
0.02
5.6E+3
9.7E+4
7.0E-3
4-1
0.02
5.5E+3
9.7E+4
7.0E-3
4-2
0.02
5.7E+3
1.0E+5
7.3E-3
5-1
0.02
5.5E+3
9.7E+4
7.0E-3
5-2
0.02
5.5E+3
9.4E+4
6.8E-3
a - Sludge volume and sludge BOD is based on CAPDETWorks™ modeling.
However, currently, about 71 percent of CH4 generated from municipal solid waste
landfills is converted to CO2 before it is released to the environment. 10.6 percent is flared, 56.8
percent is burned with energy recovery, and about 3.8 percent is oxidized as it travels through the
landfill cover based on the Inventory of U.S. GHG emissions and sinks (U.S. EPA, 2015b).
Overall, only approximately 29 percent of the total CH4 generated is released as methane without
treatment. The net CH4 emissions from sludge in a landfill, calculated by applying the percentage
of CH4 released without treatment to raw CH4 emissions reported in Table F-5, is provided in
Table F-6.
Table F-6. Methane Emissions from Sludge Disposal in Landfills after Treatment
S\s(em
( oiifi^ur;iiion l.e\el
Kiiw ( ll4 Liimirill
1'111 issions. kg ( IL /ill'
wastewater'
"/» ( II4 Released without
1 reiilmeiil
( II4 Keleiised wilhoui
1 reiilmenl/m' «iislew siler
1
8.9E-3
29%
2.6E-3
2-1
7.3E-3
29%
2.1E-3
2-2
9.8E-3
29%
2.8E-3
3-1
7.0E-3
29%
2.0E-3
3-2
7.0E-3
29%
2.0E-3
4-1
7.0E-3
29%
2.0E-3
4-2
7.3E-3
29%
2.1E-3
5-1
7.0E-3
29%
2.0E-3
5-2
6.8E-3
29%
1.9E-3
a - Derived from Table F-5 results.
The U.S. EPA's Landfill Methane Outreach Program Landfill Database indicates that the
majority of landfill gas burned with energy recovery is used to produce electricity (U.S. EPA,
KP-C-16-003; WA 2^37
F-7
-------
Appendix F: Detailed Air Emissions Methodology
2016). The gross energy recovered from combustion of sludge landfill is converted to displaced
quantities of grid electricity using an efficiency factor of 1 kWh generated per 11,700 Btu (or
12.34 MJ) of landfill CH4 burned (U.S. EPA, 2014). Each system configuration is credited with
avoiding the GWP associated with production of the offset quantity of grid electricity. The
calculations to derive this offset or avoided electricity per system configuration level are shown
in Table F-7.
Table F-7. Electricity Generation from Landfill Methane Energy Recovery
Stslcm
( milieur;iiioii
l.c\el
K:i\\ ( II4 l.iiiHllill
l-'missittus. kii
(114/111'
"i. ( II4
liui'iiod with
I.IIOIliV
Ucc(i\or\
k»( ll4 limned
with r.ncriiv
UcT
-------
Appendix F: Detailed Air Emissions Methodology
Table F-8. Biogas Flaring Emission Factors (All values are kg/m3Biogas Flared)
((impound
liiirlii/'1
Alhi'i'lii l.imnmnu'iH h
lln\ immiHwil
( iiiiiidii'
1 his Siiuh
(M;i\ \ ;iIik')
Sulfur Oxide s>
4.3L-4
9.2L-5
4.3L-4
Carbon Monoxide
6.2E-3
5.6E-5
6.2E-3
Ammonia
1.8E-5
1.8E-5
Hydrogen Sulfide
3.9E-6
3.9E-6
PAH
8.7E-6
8.7E-6
Sources:
a - Levis, J.W., and Barlaz, M.A. 2013. Anaerobic Digestion Process Model Documentation. North Carolina State
University. http://www4.ncsu.edu/~iwlevis/AD.pdf. Accessed 5 April, 2016
b - Alberta Environment. 2007. Quantification Protocol for the Anaerobic Decomposition of Agricultural
Materials Project: Excel Biogas Calculator. http://environment.gov.ab.ca/info/librarv/7917.pdf. Accessed 5
April, 2016.
c - Environment Canada. 2005. Biogas Flare. https://www.ec.gc.ca/inrp-npri/14618D02-387B-469D-BlCD-
42BC61E51652/biogas flare e 04 02 2009.xls. Accessed 5 April, 2016
KP-C-16-003; WA 2^37
F-9
-------
Appendix G: Example LCI Data Calculations
APPENDIX G
EXAMPLE LCI DATA CALCULATIONS
EP-C-I6-QQ3; WA 1^37
-------
Appendix G: Example LCI Data Calculations
Appendix G: Example LCI Data Calculations
CAPDETWorks™ design and costing software (Hydromantis, 2014) provides the main
source of LCI data for treatment plant unit process construction and operation. The relevant
elements of the CAPDETWorks™ model output were imported into an Excel document where
supplemental calculations were performed to standardize flows to be on the basis of physical
units per cubic meter of treated wastewater. Calculation procedures were similar regardless of
treatment level. Output LCI associated with the Level 1 treatment system is included in Table
G-l to provide an example of the procedure applied to all treatment levels. Supplementary LCI
calculations not associated with CAPDETWorks™ output (e.g., process-level air emissions) are
described elsewhere in the report.
KP-C-16-003; WA 2^37
G-l
-------
Appendix G: Example LCI Data Calculations
Table G-l. Example Standardization of CAPDETWorks™ Output to LCI per m3 of Treated Wastewater (Level 1)
( l/-7>/:TM oiks'xl Model Output
( ulcultilctl I.CI 1 ulucs
I nil
Description
YsiIik*
I nils
( iilcnliilcd l-'low
I nils
Value
Assumptions
(iiil kcnun;il
1 !nciii\ cosi
s \ r
i :kvuicii\
k\\ ll 111
vm:-';
so In k\\ h
Structural
40
years
Building
m2/m3
3.4E-8
structural lifespan 40 years
Area of pump building
201
sqft
Electrical energy required
10,100
kWh/yr
Electricity, Total
kwh/m3
8.4E-4
Primary
Electrical energy required
1,510
kWh/yr
Clarifier
Volume of earthwork required
129,000
cuft
Earthwork, Total
m3/m3
2.7E-6
plant lifespan of 100 years
Volume of earthwork required
1,610
cuft
Volume of slab concrete required
10,700
cuft
Concrete, Total
m3/m3
9.5E-7
structural lifespan 40 years
Volume of wall concrete required
7,810
cuft
Electrical energy required
1,880,000
kWh/yr
Electricity, Total
kwh/m3
0.14
Electrical energy required
113,000
kWh/yr
Volume of earthwork required
176,000
cuft
Earthwork, Total
m3/m3
3.7E-6
plant lifespan of 100 years
Plug Flow
Activated
Volume of earthwork required
2,670
cuft
Structural
40
years
Concrete
m3/m3
5.9E-6
structural lifespan 40 years
Sludge
Volume of slab concrete required
75,900
cuft
Volume of wall concrete required
38,200
cuft
Handrail length
1,290
ft
Steel
kg/m3
6.4E-6
lifespan of 40 years
Area of pump building
334
sqft
Building
m2/m3
5.6E-8
lifespan of 40 years
Electrical energy required
11,100
kWh/yr
Electricity, Total
kwh/m3
1.0E-3
Electrical energy required
6,500
kWh/yr
Volume of earthwork required
216,000
cuft
Earthwork, Total
m3/m3
4.5E-6
plant lifespan of 100 years
Secondary
Volume of earthwork required
1,630
cuft
Clarifier
Structural
40
years
Concrete, Total
m3/m3
1.4E-7
structural lifespan 40 years
Volume of slab concrete required
17,000
cuft
Volume of wall concrete required
9,830
cuft
Area of pump building
204
sqft
Building
m2/m3
3.4E-8
structural lifespan 40 years
KP-C-16-001
G-2
-------
Appendix G: Example LCI Data Calculations
Table G-l. Example Standardization of CAPDETWorks™ Output to LCI per m3 of Treated Wastewater (Level 1)
( l/-7>/:TM oiks'xl Model Output
( ulcultilctl I.CI 1 ulucs
I nil
Description
YsiIik*
I nils
( iilcnliilcd l-'low
I nils
Yiilnc
Assumptions
A\ erage elilorine required
X.""
lb. d
Chlorine
k'j in
(i (i |
operales ^
-------
Appendix G: Example LCI Data Calculations
Table G-l. Example Standardization of CAPDETWorks™ Output to LCI per m3 of Treated Wastewater (Level 1)
( l/-7>/:TM oiks'xl Model Output
( ulcultilctl I.CI 1 ulucs
I nil
Description
YsiIik*
I nils
( iilcnliilcd l-'low
I nils
Yiilnc
Assumptions
Gab produced
1U"
cull nun
1 iiogas, production
in in
u i:
com i iiuous production
Electrical energy required
253,000
kWh/yr
Electricity
kwh/m3
0.02
Volume of earthwork required
196,000
cuft
Earthwork
m3/m3
4.0E-6
plant lifespan of 100 years
Structural
40.0
years
Concrete, Total
m3/m3
1.8E-6
structural lifespan 40 years
Anaerobic
Digester
Volume of slab concrete required
6,860
cuft
Volume of wall concrete required
27,300
cuft
Length of total piping system
833
ft
Steel
kg/m3
2.4E-5
8" steel pipe, 16.2 kg/ft,
lifespan 40 years
Surface area/floor of 2-story
2.0E-7
control bldg..
1,180
sqft
Building
m2/m3
Heat required
1,350,000
BTU/hr
Natural Gas
m3/m3
0.02
38.4 MJ/m3 Gas HHV
Polymer dosage
248
lb/d
Polymer
kg/m3
2.1E-3
operates 5 days per week
Centrifuge
Electrical energy required
237,000
kWh/yr
Electricity
kwh/m3
0.02
Area of building
453
sqft
Building
m2/m3
7.6E-8
structural lifespan 40 years
Volume of earthwork required
26,700
cuft
Earthwork
m3/m3
5.5E-7
plant lifespan of 100 years
Structural
40
years
Concrete
m3/m3
5.7E-7
structural lifespan 40 years
Sludge
Hauling
&
Volume of slab concrete required
11,100
cuft
Sludge storage shed area
10,100
sqft
Building, Total
m2/m3
3.4E-6
structural lifespan 40 years
Landfill
Surface area of canopy roof
10,100
sqft
ton-
0.09
25 km haul distance, 365
Sludge hauled
80,286
kg/day
Truck Transport
km/m3
days per year
KP-C-16-003; WA 2^37
G-4
-------
Appendix H: Summary LCI Result
APPENDIX H
SUMMARY LCI RESULTS
EP-C-I6-QQ3; WA 2^37
-------
Appendix H: Summary LCI Result
Appendix H: Summary LCI Result
Table H-l. LCI for Level 1: Conventional Plug Flow Activated Sludge
Wastewater Treatment Configuration (per m3 wastewater treated)
l nil.
(>|irr:iliini
InlVii'-lriiiliMV
I'.lt't'l I'it'il \
Viliirul
<.;i-
( lilcii im-
<.;i-
l'< »l\ mil
lii-ullllr
i4ir..i
11 in U
1 i;mi-|)miI
Dillr-lrr (in-.
1 LmviI '
( Hi
l.iiii'-'-iMiis
V<>
l\ini—¦ion-
I ciidcd i
ImiIIiwiuU
( uncivil'
liuililiii!!
Sll-I-I
/.///; m1
ill' ill'
/..V m'
/. .V m'
/..V /II'
/A /ii in '1'
ill' ill'
/.,v III'
/..V iii.V
/. II h in i
iii' ill'
in' ill'
nr iii'
/..V in'
Screening and Grit Removal
3.4E-3
Primary Clarifier
8.6E-4
2.7E-6
1.2E-6
3.4E-8
Plug Flow Activated Sludge
0.14
3.3E-4
4.8E-5
3.7E-6
5.8E-6
5.6E-8
6.4E-6
Secondary Clarifier
1.3E-3
4.5E-6
1.9E-6
3.4E-8
Chlorination
9.5E-3
1.0E-2
4.9E-7
7.0E-7
3.4E-7
Dechlorination
9.5E-3
3.8E-3
8.1E-8
1.9E-7
1.5E-7
Effluent Release a
2.4E-4
Gravity Thickener
7.5E-4
3.0E-7
1.9E-7
Anaerobic Digester
0.02
0.04
0.12
2.5E-3
5.0E-6
2.0E-6
2.4E-7
2.6E-5
Centrifuge
0.02
2.1E-3
8.4E-8
Sludge Hauling and Landfill
0.09
2.6E-3
0.02
5.5E-7
5.7E-7
3.4E-6
Totals
0.20
0.04
1.0E-2
2.1E-3
3.8E-3
0.09
0.12
5.4E-3
2.9E-4
0.02
1.7E-5
1.3E-5
4.4E-6
3.2E-5
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table F-8
EP-C-I6-QQ3; WA 2^37
H-l
-------
Appendix H: Summary LCI Result
Table H-2. LCI for Level 2-1: Anaerobic/Anoxic/Oxic Wastewater
Treatment Configuration(per m3 wastewater treated)
< >|H-mlioii
liilr:i-lriiiluri'
r.lt't'l I'ii'il \
Viliirul
<.;i-
( liluriiir
<.;i-
l'«»l\ iiui
Uisiilllir
1 link
1 I':iii<>|ImI'I
Diilr-Irr (Ja-.
1 Imvil '
(II.
linK-ion-
V<>
lini--
r.lt't'l I'it'il \
i V\oiilt-il i
KiirllmurU
( Mlll'IVll'
liuililiii!!
Sll-l-l
l ml
/. II li in'
ill' ill'
/..V ;n'
/..v m:
/..v m:
thin in'''
ill' ill'
/..V ill'
/• " in
/. II h in'
in' ill'
in'in'
nr iii'
/..V ;n'
Screening and (Jril Removal
3.4E-3
Primary Clarifier
8.5E-4
2.6E-6
1.1E-6
3.4E-8
Biological Nutrient
Remo val-3 - Stage
0.43
3.3E-3
2.1E-4
9.5E-6
1.2E-5
1.2E-7
1.6E-5
Secondary Clarifier
1.1E-3
4.5E-6
1.9E-6
3.4E-8
Chlorination
9.5E-3
1.0E-2
4.9E-7
7.0E-7
3.4E-7
Dechlorination
9.5E-3
3.8E-3
8.1E-8
1.9E-7
1.5E-7
Effluent Release a
6.3E-5
Gravity Thickener
7.1E-4
2.6E-7
1.8E-7
Anaerobic Digester
0.02
0.04
0.10
2.1E-3
5.0E-6
2.0E-6
2.4E-7
2.6E-5
Centrifuge
0.01
1.8E-3
7.8E-8
Sludge Hauling and Landfill
0.07
2.1E-3
0.02
4.7E-7
4.9E-7
2.9E-6
Totals
0.48
0.04
1.0E-2
1.8E-3
3.8E-3
0.07
0.10
7.5E-3
2.8E-4
0.02
2.3E-5
1.9E-5
3.9E-6
4.2E-5
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table F-8.
EP-C-I6-QQ3; WA 2^37
H-2
-------
Appendix H: Summary LCI Result
Table H-3. LCI for Level 2-2: Activated Sludge, 3-Sludge System Wastewater Treatment Configuration
(per m3 wastewater treated)
()|H'ialion
Iiilr:i-lriii1iirc
l.lrcl I'ii'il \
Nalural
(ia*>
( Murine
(ias
l'<»l\ lllfl
"mmImiiii
liKiillllr
(40".. i
VI
^iillalr
( all ium
( arlmnalc
Mt'lhaiiol
1 link
1 Ull-pcill
Dillr-lrr
1 Lnvil '
( Hi
I'liii'.'.iMiis
V<>
linissioiis
r.lt't'l I'ii'il \
i V\oiilt-il i
KiirllmurU
( Mlli l clr
liuililiii!!
Mi-i-l
I III/.
/»II h in'
in' in
/..v III'
/..v m!
/..v m:
/..v III'
/..v III'
/..v III'
ihlll III' ''
ill' ill'
/..v III'
/..v m:
/. II li in'
in'in'
ill' ill'
nr in'
/..V ill'
Screening and (Jril
Removal
3.4E-3
Primary Clarifier
8.8E-4
2.7E-6
1.2E-6
3.4E-8
Plug Flow Activated
Sludge
0.15
3.3E-3
2.8E-5
3.8E-6
6.1E-6
5.6E-8
6.6E-6
Chemical Phosphorus
Removal
0.08
Nitrification -
Suspended Growth
0.16
0.21
3.8E-6
6.1E-6
5.6E-8
6.6E-6
Denitrification -
Suspended Growth
0.13
0.05
2.3E-6
1.8E-6
5.6E-8
Secondary Clarifier
1.3E-3
4.5E-6
1.9E-6
3.4E-8
Tertiary Clarification
(Nitrification)
8.3E-4
4.5E-6
1.9E-6
3.4E-8
Tertiary Clarification
(Denitrification)
1.0E-3
4.5E-6
1.9E-6
3.4E-8
Chlorination
9.5E-3
1.0E-2
4.9E-7
7.0E-7
3.4E-7
Dechlorination
9.5E-3
3.8E-3
8.1E-8
1.9E-7
1.5E-7
Effluent Release a
6.1E-5
Gravity Thickener
8.2E-4
3.8E-7
2.3E-7
Anaerobic Digester
0.02
0.06
0.13
2.8E-3
6.6E-6
2.7E-6
3.0E-7
3.5E-5
Centrifuge
0.02
3.2E-3
9.0E-8
Sludge Hauling and
Landfill
0.13
2.8E-3
0.03
8.1E-7
8.4E-7
5.1E-6
Totals
0.51
0.06
1.0E-2
3.2E-3
3.8E-3
0.08
0.21
0.05
0.13
0.13
8.9E-3
8.9E-5
0.03
3.4E-5
2.5E-5
6.3E-6
4.8E-5
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table F-8.
EP-C-I6-QQ3; WA 2^37
H-3
-------
Appendix H: Summary LCI Result
Table H-4. LCI for Level 3-1: 5-Stage Bardenpho System Wastewater Treatment Configuration
(per m3 wastewater treated)
(>|»r;ilioll
lnlr:i-l rilillMT
^Milium
Niiliirul
( Murine
Ui-llllllr
1 link
l)ii!i">lrr
( II.
V<>
lliTliilin
<.;i-
I'llljiiici
VI ^iilliilr
1 lllll-pcill
1 Lnvil '
lini-viMii-
lini--ion-
( V\Milled i
KiirllmurU
( uncivil'
liuililiii!!
Slffl
siiiiiI
(miiM'I
Vnlliriii'ilc
l ml
/.///; m1
ill' ill'
/>." in
/..V m1
Ill
/'." in
thill III' ''
ill' ill'
/..V m1
/..V m1
IJlli in1
in'in'
ill' in'
nr in'
/..V ill1
/..V ill1
/..V III1
/• " in
Screening and
Grit Removal
3.4E-3
Primary Clarifier
8.5E-4
2.6E-6
1.1E-6
3.4E-8
Fermenter
8.8E-4
2.1E-7
1.4E-7
Biological
Nutrient
0.46
8.4E-3
5.7E-4
1.1E-5
1.4E-5
1.2E-7
1.9E-5
Remo val-5 - Stage
Chemical
Phosphorus
Removal
4.2E-3
Secondary
Clarifier
1.2E-3
4.5E-6
1.9E-6
3.4E-8
Filtration-Sand
Filter
5.6E-3
2.7E-6
1.6E-6
1.1E-3
4.0E-4
2.7E-4
Chlorination
9.5E-3
8.0E-3
4.9E-7
7.0E-7
2.7E-7
Dechlorination
9.5E-3
3.8E-3
8.1E-8
1.9E-7
1.5E-7
Effluent Release a
4.7E-5
Gravity Thickener
7.1E-4
2.6E-7
1.8E-7
Anaerobic
Digester
0.02
0.04
0.09
2.0E-3
5.0E-6
2.0E-6
2.4E-7
2.6E-5
Centrifuge
0.01
1.8E-3
7.9E-8
Sludge Hauling
and Landfill
0.07
2.0E-3
0.02
4.7E-7
4.9E-7
2.9E-6
Totals
0.52
0.04
8.0E-3
1.8E-3
3.8E-3
4.2E-3
0.07
0.09
0.01
6.2E-4
0.02
2.7E-5
2.2E-5
3.9E-6
4.5E-5
1.1E-3
4.0E-4
2.7E-4
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table F-8.
EP-C-I6-QQ3; WA 2^37
H-4
-------
Appendix H: Summary LCI Result
Table H-5. LCI for Level 3-2: Modified University of Cape Town Process Wastewater Treatment Configuration
(per m3 wastewater treated)
< )|H'l'Sllio||
liilr:i-lriiilu
V
l.lrcl rii'il \
Nalural
(iih
( hlui'iiii'
(ins
l'o|\ lllt'l
"hmImmii
liKulllU-
w
1 link
1
1 hi ml '
( Hi
I'.iiii'.'.iMiis
V<>
linissioiis
llriliiiil\
i V\oiilt-il i
KiirllmurU
( Mlli l clr
liuililiii!!
Mi-i-l
Nilllll
(¦ ra\ rl
tnlliraiilc
I III/
AII h in'
in' in
/..v III'
/..V III'
/..v /II
/..v III'
ihlll III' *
ill' ill'
/..v III'
/..v m:
Mlh m1
in'in'
III' III'
nr in'
/..V ill'
/..V III'
/..v III'
/..v III'
Screening and
Grit Removal
3.4E-3
-
-
-
-
Primary
Clarifier
8.5E-4
2.6E-6
1.1E-6
3.4E-8
-
Fermenter
8.8E-4
2.1E-7
1.4E-7
-
-
Biological
Nutrient
Removals-
Stage
0.51
8.4E-3
2.2E-4
1.1E-5
1.4E-5
1.1E-7
1.9E-5
Chemical
Phosphorus
Removal
4.2E-3
Secondary
Clarifier
1.2E-3
4.5E-6
1.9E-6
3.4E-8
-
Filtration-Sand
Filter
5.6E-3
2.7E-6
1.6E-6
-
-
1.1E-3
4.0E-4
2.7E-4
Chlorination
9.5E-3
8.0E-3
4.9E-7
7.0E-7
2.7E-7
-
Effluent
Release a
4.7E-5
Dechlorination
9.5E-3
3.8E-3
8.1E-8
1.9E-7
1.5E-7
-
Gravity
Thickener
7.1E-4
2.6E-7
1.8E-7
-
-
Anaerobic
Digester
0.02
0.04
0.09
2.0E-3
5.0E-6
2.0E-6
2.4E-7
2.6E-5
Centrifuge
0.01
1.8E-3
-
-
7.9E-8
-
Sludge Hauling
and Landfill
0.07
2.0E-3
0.02
4.7E-7
4.9E-7
2.9E-6
-
Totals
0.57
0.04
8.0E-3
1.8E-3
3.8E-3
4.2E-3
0.07
0.09
0.01
2.6E-4
0.02
2.7E-5
2.2E-5
3.9E-6
4.5E-5
1.1E-3
4.0E-4
2.7E-4
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table F-8.
EP-C-I6-QQ3; WA 2^37
H-5
-------
Appendix H: Summary LCI Result
Table H-6. LCI for Level 4-1: 5-Stage Bardenpho System with Denitrification Filter Wastewater Treatment Configuration
(per m3 wastewater treated)
( nit:
< >|HT;iiiiui
liirr.isiniriiiri-
1- lirir
u-iix
C.IS
< Murine
C.IS
I'hImii CI'
ShiIiimii
liiMilliii
(4ii" n)
\\ Siill
:i 11-
Mil
ll.lliul
1 link
1 r.ms> |»ui i
|)lt>i'SU'l' < i.iv.
1 Liiiil
< 1 1 | 1- IlllVt
lulls.
\ I- IIIISS
lulls
Hid nriix
( V\ u 1 tli-tl)
l-.irili wurk
< ulliTlll-
l»iiil(lnit>
Slnl
ViiiiI
( il .H l l
Anilir.inii'
kli h m!
m{ m*
kg nrt
kg nr!
kg m!
kg
kg nr!
tkm m{
m{ m{
kg m'!
kg m!
kWh m1
m3 m!
m{ m1
m2 m!
kg m!
kg m1
kg m!
kg nr!
0
Grit Removal
\
Primary Clarifier
8.5E-4
2.6E-6
1.1E-6
3.4E-8
Fermenter
8.8E-4
2.1E-7
1.4E-7
-
Biological
Nutrient
Removal-5 - Stage
0.46
8.4E-3
5.7E-4
1.1E-5
1.4E-5
1.2E-7
1.9E-5
Chemical
Phosphorus
Removal
4.2E-3
Secondary
Olarifier
1.2E-3
4.5E-6
1.9E-6
3.4E-8
Denitrification -
Attached Growth
0.13
0.02
1.5E-6
1.1E-6
1.9E-7
2.8E-4
1.2E-4
Filtration-Sand
Filter
5.6E-3
2.7E-6
1.6E-6
1.1E-3
4.0E-4
2.7E-4
Ohlorination
9.5E-3
8.0E-3
4.9E-7
7.0E-7
2.7E-7
Dechlorination
9.5E-3
3.8E-3
8.1E-8
1.9E-7
1.5E-7
Effluent Release a
2.3E-5
Gravity
Thickener
7.1E-4
2.6E-7
1.8E-7
Anaerobic
Digester
0.02
0.04
0.09
2.0E-3
5.0E-6
2.0E-6
2.4E-7
2.6E-5
Centrifuge
0.01
1.8E-3
7.9E-8
Sludge Hauling
and Landfill
0.07
2.0E-3
0.02
4.7E-7
4.9E-7
2.9E-6
Totals
0.65
0.04
8.0E-3
1.8E-3
3.8E-3
4.2E-3
0.02
0.07
0.09
0.01
6.0E-4
0.02
2.9E-5
2.3E-5
4.1E-6
4.5E-5
1.4E-3
5.3E-4
2.7E-4
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table C-8.
EP-C-I6-QQ3; WA 2^37
H-6
-------
Appendix H: Summary LCI Result
Table H-7. LCI for Level 4-2: 4-Stage Bardenpho Membrane Bioreactor System Wastewater Treatment Configuration
(per m3 wastewater treated)
< )|H'l'Sllio||
llllr:i-l rilillllr
r.lt't'l I'it'il \
Nulurul
<.;i-
( lilcii im-
<.;i-
l'i»l\ lllt'l
^Milium
lii-llllllr
w
1 link
1 i;mi-|>miI
1
1 lillVll '
( II.
Iini—¦ion-
V<>
linissioiis
rilt-t-l rit-il \
i VMiiilril i
KiirllmurU
( Mllrli-lr
liuililiii!!
Sll-l-l
l ml
l,llli m1
ill' ill'
/..V ;n'
/..V ;n'
/..V ;n'
/..v m:
ihlll III' ''
ill' ill'
/..V ill'
/..v III'
AII h in'
ill' in'
ill' ill'
nr in'
/..V /II
Screening and (Jril
Removal
3.4E-3
-
-
-
-
Primary Clarifier
8.5E-4
2.6E-6
1.1E-6
3.4E-8
-
Biological Nutrient
Remo val-4- Stage
0.35
8.4E-3
5.6E-4
5.5E-6
7.8E-6
1.2E-7
9.4E-6
Chemical Phosphorus
Removal
2.2E-3
-
-
-
-
Membrane Filter
0.23
1.5E-6
3.1E-6
8.2E-8
5.4E-6
Chlorination
9.5E-3
8.0E-3
4.9E-7
7.0E-7
2.7E-7
-
Dechlorination
9.5E-3
3.8E-3
8.1E-8
1.9E-7
1.5E-7
-
Effluent Release a
2.4E-5
-
-
-
-
Gravity Thickener
7.0E-4
2.6E-7
1.8E-7
-
-
Anaerobic Digester
0.02
0.03
0.09
2.0E-3
4.5E-6
1.9E-6
2.2E-7
2.5E-5
Centrifuge
0.01
1.8E-3
-
-
7.8E-8
-
Sludge Hauling and
Landfill
0.07
2.1E-3
0.02
4.6E-7
4.8E-7
2.9E-6
-
Totals
0.64
0.03
8.0E-3
1.8E-3
3.8E-3
2.2E-3
0.07
0.09
0.01
5.9E-4
0.02
1.5E-5
1.5E-5
3.8E-6
4.0E-5
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table C-8.
EP-C-I6-QQ3; WA 2^37
H-7
-------
Appendix H: Summary LCI Result
Table H-8. Operational LCI for Level 5-1: 5-Stage Bardenpho with Sidestream Reverse Osmosis Wastewater Treatment Configuration
(per m3 wastewater treated)
( nit:
1- li rli iril x
Viiunil
< Murine
C.IS
I'hImiut
ShiIiimm
lilMllllU
(411".. \ 2.r-
\\
Sull.iU
Mi'lll.llinl
\niiM-.il.ini
lilllK
lii.|iriiuii
(\\ .ii i i'
1 i.ss)
1 link
1 l'.ll|S|)H|l
< ili n-
\tiil
Sodium
11\ |)Hrlilunii'
Siiirui'ir
\flll
Snilllllll
1 l\ (ll'HMlli-
Dim-sii'i'
c.is.
1 l.il'i'd '
< Mi
1- IIIISSlHllS
\.<>
1- llllsviulis
1- li-rii'iciix
( uiili ih
k Wit m1
kfi m!
kg nr!
kfi m'
kfi nr1
kg nr!
kfi nr*
tkm m 3''
kg m!
kf;
kfi mt
kfi m1
m{ nri
kg m!
kfi tn!
k IVh m1
...
3.4E-3
Primary Clarifier
8.5E-4
Fermenter
8.8E-4
Biological
Nutrient Removal
- 5-Stage
0.46
8.4E-3
5.7E-4
Chemical
Phosphorus
Removal
4.2E-3
Secondary
Clarifier
1.2E-3
Denitrification -
Attached Growth
0.01
2.3E-3
Filtration - Sand
Filter
5.9E-4
Chlorination
9.1E-3
4.9E-3
Dechlorination
9.1E-3
7.5E-3
Ultrafiltration
0.17
4.0E-4
1.6E-3
9.9E-4
1.2E-3
3.9E-3
Reverse Osmosis
0.46
2.7E-3
9.5E-4
Effluent Release a
5.0E-6
Gravity Thickener
7.1E-4
Anaerobic
Digester
0.02
0.04
0.09
2.0E-3
Centrifuge
0.01
1.8E-3
Sludge Hauling
and Landfill
0.07
2.0E-3
0.02
Underground
Injection of Brine
0.33
0.18
2.7E-5
Totals
1.5
0.04
4.9E-3
1.8E-3
7.9E-3
4.2E-3
2.3E-3
2.7E-3
0.18
0.07
2.5E-3
9.9E-4
1.2E-3
3.9E-3
0.09
0.01
5.8E-4
0.02
a - All effluent release emissions are presented in Table 1-4.
b -tkm is an abbreviation for ton-kilometers,
c - Biogas flaring emissions are presented in Table C-8.
EP-C-I6-QQ3; WA 2^37
H-8
-------
Appendix H: Summary LCI Result
Table H-9. Infrastructure LCI for Level 5-1: 5-Stage Bardenpho with Sidestream Reverse Osmosis Wastewater Treatment Configuration
(per m3 wastewater treated)
I-! a rlli work
( MIHTl'U'
Building
Su-il
Sand
(¦raM'l
Anlhraiili'
I nil:
l/l-> //!->
//!-> //!->
f/l- //!->
//i.>
//i.>
/.£ //!.>
//i.>
Screening and Grit Removal
Primary Clarifier
2.6E-6
1.1E-6
3.4E-8
Fermenter
2.1E-7
1.4E-7
Biological Nutrient Removal - 5-Stage
1.1E-5
1.4E-5
1.2E-7
1.9E-5
Chemical Phosphorus Removal
Secondary Clarifier
4.5E-6
1.9E-6
3.4E-8
Denitrification - Attached Growth
3.2E-7
4.1E-7
8.5E-8
2.8E-5
1.2E-5
Filtration - Sand Filter
3.9E-7
2.2E-7
1.1E-4
4.0E-5
2.7E-5
Chlorination
4.0E-7
5.9E-7
2.0E-7
Dechlorination
6.7E-8
1.8E-7
2.3E-7
Ultrafiltration
2.6E-6
-
2.7E-6
Reverse Osmosis
1.6E-6
-
1.7E-6
Gravity Thickener
2.6E-7
1.8E-7
Anaerobic Digester
5.0E-6
2.0E-6
2.4E-7
2.6E-5
Centrifuge
7.9E-8
Sludge Hauling and Landfill
4.7E-7
4.9E-7
2.9E-6
Underground Injection of Brine
2.8E-8
2.7E-5
Totals
2.9E-5
2.1E-5
8.4E-6
7.2E-5
1.4E-4
5.3E-5
2.7E-5
EP-C-I6-QQ3; WA 2^37
H-9
-------
Appendix H: Summary LCI Result
Table H-10. LCI for Level 5-2: 5-Stage Bardenpho Membrane Bioreactor
with Sidestream Reverse Osmosis Wastewater Treatment Configuration
(per m3 wastewater treated)
( nit:
< >|HT.ll|n||
1 riii-i iiri-
1- li rli iril x
Viiunil
(i;is
< lllnl liu-
C.is
1'ulMIUI-
ShiIiimii
liiMilliii (4n» „)
\\
Silll'.ilr
\llllM-.ll.llll
IllllK
lii.|irliuii
(N .Hit 1 ns\)
1 link
1 IMII'h|>h|-|
( iinr
Wiil
DiiilsIlT < i.|s.
1 l.ilril "
< 114
1- IIIISSlHllS
1- IIIISSlHllS
1- ln irn ii \
( \\ Hllli ll)
l-.irili\\Hik
< HlitTi-li-
lilllltllllL*
Mill
k Wh m1
nr{ m1
kg nr1
kfi nr!
kfi nr!
kfi nr!
kg nr1
nr{ m!
tkm nr!''
kg nr!
m { nr{
kfi m!
kfi nr!
kWh m1
nr* mi
m* m!
m2 nr
kg nr{
Screening and Grit Removal
3.4E-3
Primary Clarifier
8.5E-4
2.6E-6
1.1E-6
3.4E-8
Fermenter
8.8E-4
2.1E-7
1.4E-7
Biological Nutrient Removal
- 5-Stage
0.39
8.4E-3
5.7E-4
5.3E-6
7.6E-6
1.2E-7
9.1E-6
Chemical Phosphorus
Removal
2.1E-3
Membrane Filter
0.23
1.5E-6
3.1E-6
8.3E-8
5.4E-6
Ohlorination
9.1E-3
5.0E-3
4.8E-7
6.9E-7
2.0E-7
Dechlorination
9.1E-3
7.5E-3
8.0E-8
1.9E-7
2.3E-7
Reverse Osmosis
0.44
2.5E-3
8.9E-4
1.6E-6
-
1.7E-6
Effluent Release a
1.3E-5
Gravity Thickener
7.0E-4
2.1E-7
1.5E-7
Anaerobic Digester
0.02
0.03
0.09
1.9E-3
4.0E-6
1.8E-6
2.0E-7
2.4E-5
Centrifuge
0.01
1.7E-3
7.7E-8
Sludge Hauling and Landfill
0.07
2.0E-3
0.02
4.5E-7
4.7E-7
2.8E-6
Underground Injection of
Brine
0.33
0.17
2.7E-5
2.8E-8
2.7E-5
Totals
1.4
0.03
5.0E-3
1.7E-3
7.5E-3
2.1E-3
2.5E-3
0.17
0.07
8.9E-4
0.09
0.01
5.8E-4
0.02
1.6E-5
1.5E-5
5.4E-6
6.6E-5
EP-C-I6-QQ3; WA 2^37
H-10
-------
Appendix H: Summary LCI Result
Table H-ll. Sludge Quantity Produced by Wastewater Treatment Configuration
\\ iislowiilor 1 iviilmonl
( onri^iii'iiiioii
kji SIikI^c/ih'" \\ ;isU'\\;Mer 1 iv;i(od''
"ii (linnlie lo l.c\ol 1. AS
Level 1, AS
0.26
-
Level 2-1, A20
0.22
-15%
Level 2-2, AS3
0.38
48%
Level 3-1, B5
0.22
3%
Level 3-2, MUCT
0.22
3%
Level 4-1, B5/Denit
0.22
4%
Level 4-2, MBR
0.22
4%
Level 5-1, B5/RO
0.22
4%
Level 5-2, MBR/RO
0.21
0%
a 21 percent moisture
EP-C-I6-QQ3; WA 2^37
H-ll
-------
Appendix I: Cost Results by Unit Process
APPENDIX I
COST RESULTS BY UNIT PROCESS
KP-C-16-003; WA 2^37
-------
Appendix I: Cost Results by Unit Process
Appendix I: Cost Results by Unit Process
This Appendix provides cost results by unit process using the 3% interest and discount
rates. Table 1-1 and Table 1-2 display the detailed results for the total construction costs and total
annual costs by unit process. Table 1-3 through Table 1-7 display the detailed results by total
annual cost component (e.g., operational labor, maintenance labor) by unit process. Net present
value was not calculated by unit process.
KP-C-16-003; WA 2^37
1-1
-------
Appendix I: Cost Results by Unit Process
Table 1-1. Total Construction Costs by Detailed Unit Process (2014 $)
Pnni-ss
IamI 1,
AS
IamI 2-1,
\2()
IamI 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/I)i'iiil
Iam I 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
Iam I 5-2.
Mlik/k()
Screening and grit removal
$1,890,000
$1,890,000
$1,900,000
$1,890,000
$1,890,000
$1,888,000
$1,890,000
$1,888,000
$1,890,000
Primary clarifier
$1,260,000
$1,230,000
$1,260,000
$1,230,000
$1,230,000
$1,230,000
$1,230,000
$1,230,000
$1,230,000
Activated Sludge
$5,100,000
$5,260,000
Biological nutrient removal-3-stage
$12,500,000
Biological nutrient removal-4-stage
$14,800,000
$7,580,000
Biological nutrient removal-5-stage
$13,800,000
$13,800,000
$13,800,000
$8,550,000
Blower System
$715,000
$770,000
$1,150,000
$787,000
$787,000
$787,000
$2,490,000
$787,000
$2,520,000
Secondary Clarifier
$1,880,000
$1,880,000
$1,890,000
$1,880,000
$1,880,000
$1,880,000
$1,880,000
Membrane Filter
$13,300,000
$13,300,000
Nitrification, suspended growth
$5,330,000
Tertiary clarification, nitrification
$1,860,000
Denitrification, suspended growth
$1,830,000
Tertiary clarification,
denitrification
$1,880,000
Fermenter
$788,000
$788,000
$788,000
$788,000
$788,000
Chemical Phosphorus Removal
$0
$0
$0
$0
$0
$0
$0
Alum Feed System
$302,000
$214,000
$214,000
$214,000
$214,000
$214,000
$214,000
Denitrification, attached growth
$2,580,000
$560,000
Sand Filter
$3,810,000
$3,810,000
$3,810,000
$1,100,000
Ultrafiltration
$11,430,000
Reverse Osmosis
$12,990,000
$12,340,000
Chlorination
$977,000
$977,000
$977,000
$954,000
$954,000
$954,000
$955,000
$795,000
$860,000
SODechlorination
$213,000
$213,000
$213,000
$213,000
$213,000
$213,000
$213,000
$224,000
$235,000
Effluent Release
$0
$0
$0
$0
$0
$0
$0
$0
$0
Gravity Thickener
$1,090,000
$1,010,000
$1,240,000
$1,010,000
$1,010,000
$1,010,000
$1,010,000
$1,010,000
$901,000
Anaerobic Digester
$5,440,000
$5,320,000
$7,450,000
$5,320,000
$5,320,000
$5,320,000
$4,570,000
$5,320,000
$4,830,000
Centrifuge
$2,720,000
$2,370,000
$3,760,000
$2,380,000
$2,380,000
$2,380,000
$2,350,000
$2,390,000
$2,320,000
Sludge Hauling and Landfill
$988,000
$649,000
$1,320,000
$651,000
$651,000
$651,000
$644,000
$651,000
$639,000
Brine Injection Well
$7,790,000
$7,790,000
Other Costs
$33,000,000
$42,600,000
$55,500,000
$51,500,000
$53,000,000
$55,300,000
$53,700,000
$95,400,000
$86,000,000
Total
$55,300,000
$71,400,000
$93,100,000
$86,400,000
$88,900,000
$92,800,000
$90,100,000
$160,000,000
$144,000,000
KP-C-16-003; WA 2^37
1-2
-------
Appendix I: Cost Results by Unit Process
Table 1-2. Total Annual Costs by Detailed Unit Process (2014 $)
Pnni-ss
IamI 1,
AS
IamI 2-1,
\2()
IamI 2-2.
AS3
Iam I 3-1.
H5
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nii
Iam I 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
Iam I 5-2.
Mlik/k()
Screening and grit removal
$170,000
$170,000
$174,000
$170,000
$171,000
$172,000
$171,000
$171,000
$171,000
Primary clarifier
$117,000
$117,000
$120,000
$120,000
$117,000
$118,000
$118,000
$118,000
$118,000
Activated Sludge
$518,000
$532,000
Biological nutrient removal-3-stage
$1,300,000
Biological nutrient removal-4-stage
$1,540,000
$1,120,000
Biological nutrient removal-5-stage
$1,380,000
$1,380,000
$1,380,000
$1,140,000
Blower System
$0
$0
$0
$0
$0
$0
$0
$0
$0
Secondary Clarifier
$157,000
$156,000
$160,000
$157,000
$157,000
$158,000
$158,000
Membrane Filter
$1,230,000
$1,230,000
Nitrification, suspended growth
$554,000
Tertiary clarification, nitrification
$148,000
Denitrification, suspended growth
$1,370,000
Tertiary clarification,
denitrification
$155,000
Fermenter
$72,000
$72,100
$72,800
$72,500
$72,400
Chemical Phosphorus Removal
$1,210,000
$61,500
$61,500
$61,500
$31,000
$61,500
$61,300
Alum Feed System
$124,000
$37,300
$37,300
$37,300
$35,200
$37,300
$37,300
Denitrification, attached growth
$1,030,000
$372,000
Sand Filter
$128,000
$128,000
$129,000
$47,400
Ultrafiltration
$487,000
Reverse Osmosis
$1,200,000
$1,140,000
Chlorination
$313,000
$313,000
$313,000
$266,000
$267,000
$267,000
$267,000
$189,000
$193,000
Dechlorination
$121,000
$122,000
$122,000
$122,000
$122,000
$122,000
$122,000
$171,000
$173,000
Effluent Release
$0
$0
$0
$0
$0
$0
$0
$0
$0
Gravity Thickener
$75,000
$67,000
$92,800
$66,000
$66,600
$67,200
$66,800
$66,900
$64,900
Anaerobic Digester
$591,000
$526,000
$804,000
$523,000
$523,000
$525,000
$510,000
$524,000
$489,000
Centrifuge
$797,000
$717,000
$1,060,000
$720,000
$720,000
$721,000
$711,000
$720,000
$704,000
Sludge Hauling and Landfill
$1,990,000
$1,680,000
$2,910,000
$1,690,000
$1,690,000
$1,680,000
$1,660,000
$1,690,000
$1,640,000
Brine Injection Well
$479,000
$479,000
Other Costs
$288,000
$288,000
$290,000
$288,000
$288,000
$288,000
$288,000
$361,000
$360,000
Total
$5,140,000
$5,470,000
$10,150,000
$5,800,000
$5,960,000
$6,840,000
$6,330,000
$8,320,000
$8,080,000
KP-C-16-003; WA 2^37
1-3
-------
Appendix I: Cost Results by Unit Process
Table 1-3. Total Operational Labor Costs by Detailed Unit Process (2014 $)
Pnni-ss
IamI 1,
AS
IamI 2-1,
\2()
IamI 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nil
Iam I 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
Iam I 5-2.
Mlik/k()
Screening and grit removal
$100,000
$100,000
$101,000
$100,000
$100,000
$100,000
$99,800
$100,000
$99,800
Primary clarifier
$68,900
$68,700
$69,500
$68,700
$68,700
$68,700
$68,600
$68,700
$68,600
Activated Sludge
$148,000
$149,000
Biological nutrient removal-3-stage
$316,000
Biological nutrient removal-4-stage
$348,000
$276,000
Biological nutrient removal-5-stage
$320,000
$320,000
$320,000
$288,000
Blower System
$0
$0
$0
$0
$0
$0
$0
$0
$0
Secondary Clarifier
$90,800
$89,800
$91,400
$90,300
$90,300
$90,300
$90,300
Membrane Filter
$440,000
$440,000
Nitrification, suspended growth
$154,000
Tertiary clarification, nitrification
$84,900
Denitrification, suspended growth
$129,000
Tertiary clarification,
denitrification
$88,500
Fermenter
$38,600
$38,600
$38,600
$38,600
$38,400
Chemical Phosphorus Removal
$0
$0
$0
$0
$0
$0
$0
Alum Feed System
$118,000
$33,000
$33,000
$33,000
$30,900
$33,000
$33,000
Denitrification, attached growth
$554,000
$221,000
Sand Filter
$15,400
$15,400
$15,400
$4,140
Ultrafiltration
$18,800
Reverse Osmosis
$18,800
$18,800
Chlorination
$74,400
$74,400
$74,400
$66,100
$66,100
$66,100
$66,100
$51,000
$51,400
Dechlorination
$44,200
$44,200
$44,100
$44,200
$44,200
$44,200
$44,200
$57,400
$57,800
Effluent Release
$0
$0
$0
$0
$0
$0
$0
$0
$0
Gravity Thickener
$40,000
$34,900
$50,300
$34,700
$34,700
$34,700
$34,600
$34,700
$34,000
Anaerobic Digester
$134,000
$115,000
$171,000
$114,000
$114,000
$114,000
$113,000
$114,000
$111,000
Centrifuge
$570,000
$521,000
$730,000
$523,000
$523,000
$523,000
$517,000
$523,000
$512,000
Sludge Hauling and Landfill
$204,000
$173,000
$302,000
$174,000
$174,000
$173,000
$171,000
$174,000
$168,000
Brine Injection Well
$9,400
$9,400
Other Costs
$288,000
$288,000
$288,000
$288,000
$288,000
$288,000
$288,000
$361,000
$357,000
Total
$1,760,000
$1,830,000
$2,650,000
$1,910,000
$1,940,000
$2,460,000
$2,150,000
$2,240,000
$2,290,000
KP-C-16-003; WA 2^37
1-4
-------
Appendix I: Cost Results by Unit Process
Table 1-4. Total Maintenance Labor Costs by Detailed Unit Process (2014 $)
Pnni-ss
IamI 1,
AS
IamI 2-1,
\2()
IamI 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nil
Iam I 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
Iam I 5-2,
MliR/RO
Screening and grit removal
$41,700
$42,200
$44,100
$42,400
$42,500
$43,800
$43,300
$43,200
$43,400
Primary clarifier
$34,500
$34,900
$36,500
$35,100
$35,200
$36,200
$35,800
$35,700
$36,000
Activated Sludge
$74,100
$78,900
Biological nutrient removal-3-stage
$168,000
Biological nutrient removal-4-stage
$191,000
$149,000
Biological nutrient removal-5-stage
$171,000
$176,000
$174,000
$158,000
Blower System
$0
$0
$0
$0
$0
$0
$0
$0
$0
Secondary Clarifier
$45,500
$45,600
$48,000
$46,100
$46,200
$47,700
$47,000
Membrane Filter
$239,000
$241,000
Nitrification, suspended growth
$81,300
Tertiary clarification, nitrification
$43,300
Denitrification, suspended growth
$70,200
Tertiary clarification,
denitrification
$46,100
Fermenter
$24,300
$24,400
$25,100
$24,800
$24,900
Chemical Phosphorus Removal
$0
$0
$0
$0
$0
$0
$0
Alum Feed System
$0
$0
$0
$0
$0
$0
$0
Denitrification, attached growth
$216,000
$120,000
Sand Filter
$9,090
$9,110
$9,390
$2,410
Ultrafiltration
$18,800
Reverse Osmosis
$18,800
$18,800
Chlorination
$15,600
$15,800
$16,300
$12,800
$12,900
$13,200
$13,100
$8,140
$8,310
Dechlorination
$6,020
$6,120
$6,310
$12,800
$6,160
$13,200
$6,290
$10,100
$10,300
Effluent Release
$0
$0
$0
$0
$0
$0
$0
$0
$0
Gravity Thickener
$22,900
$20,700
$29,000
$20,700
$20,800
$21,400
$21,100
$21,100
$20,900
Anaerobic Digester
$72,100
$63,600
$96,100
$63,500
$63,600
$65,500
$64,500
$64,700
$63,300
Centrifuge
$31,800
$29,800
$44,400
$30,100
$30,200
$31,000
$30,500
$30,600
$30,300
Sludge Hauling and Landfill
$0
$0
$0
$0
$0
$0
$0
$0
$0
Brine Injection Well
$9,400
$9,400
Other Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
Total
$344,000
$427,000
$641,000
$461,000
$482,000
$692,000
$603,000
$629,000
$665,000
KP-C-16-003; WA 2^37
1-5
-------
Appendix I: Cost Results by Unit Process
Table 1-5. Total Material Costs by Detailed Unit Process (2014 $)
Pnni-ss
IamI 1,
AS
IamI 2-1,
\2()
IamI 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nil
Iam I 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
Iam I 5-2,
MliR/RO
Screening and grit removal
$23,600
$23,600
$23,700
$23,600
$23,600
$23,600
$23,600
$23,600
$23,600
Primary clarifier
$12,500
$12,200
$12,500
$12,200
$12,200
$12,200
$12,200
$12,200
$12,200
Activated Sludge
$97,400
$100,000
Biological nutrient removal-3-stage
$228,000
Biological nutrient removal-4-stage
$259,000
$132,000
Biological nutrient removal-5-stage
$253,000
$253,000
$253,000
$152,000
Blower System
$0
$0
$0
$0
$0
$0
$0
$0
$0
Secondary Clarifier
$18,700
$18,700
$18,700
$18,700
$18,700
$18,700
$18,700
Membrane Filter
$130,000
$130,000
Nitrification, suspended growth
$102,000
Tertiary clarification, nitrification
$18,500
Denitrification, suspended growth
$6,830
Tertiary clarification,
denitrification
$18,600
Fermenter
$7,880
$7,880
$7,880
$7,875
$7,875
Chemical Phosphorus Removal
$0
$0
$0
$0
$0
$0
$0
Alum Feed System
$6,040
$4,280
$4,280
$4,280
$4,280
$4,280
$4,280
Denitrification, attached growth
$14,200
$3,270
Sand Filter
$96,200
$96,200
$96,200
$40,000
Ultrafiltration
$124,000
Reverse Osmosis
$162,000
$153,000
Chlorination
$30,600
$30,600
$30,600
$31,400
$31,400
$31,400
$31,400
$29,300
$31,600
Dechlorination
$20,200
$20,200
$20,200
$20,200
$20,200
$20,200
$20,200
$20,600
$20,900
Effluent Release
$0
$0
$0
$0
$0
$0
$0
$0
$0
Gravity Thickener
$10,900
$10,100
$12,400
$10,100
$10,100
$10,100
$10,100
$10,100
$9,010
Anaerobic Digester
$42,400
$40,800
$59,400
$40,800
$40,800
$40,800
$39,100
$40,800
$37,400
Centrifuge
$86,400
$73,500
$128,000
$73,800
$73,800
$73,800
$72,300
$73,800
$71,400
Sludge Hauling and Landfill
$1,790,000
$1,510,000
$2,610,000
$1,520,000
$1,520,000
$1,510,000
$1,490,000
$1,520,000
$1,470,000
Brine Injection Well
$2,900
$2,900
Other Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
Total
$2,130,000
$1,970,000
$3,170,000
$2,110,000
$2,120,000
$2,120,000
$1,970,000
$2,350,000
$2,130,000
KP-C-16-003; WA 2^37
1-6
-------
Appendix I: Cost Results by Unit Process
Table 1-6. Total Chemical Costs by Detailed Unit Process (2014 $)
Pnni-ss
IamI 1,
AS
IamI 2-1,
\2()
IamI 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nil
Iam I 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
Iam I 5-2.
Mlik/k()
Screening and grit removal
$0
$0
$0
$0
$0
$0
$0
$0
$0
Primary clarifier
$0
$0
$0
$0
$0
$0
$0
$0
$0
Activated Sludge
$0
$0
Biological nutrient removal-3-stage
$0
Biological nutrient removal-4-stage
$0
$77,300
Biological nutrient removal-5-stage
$0
$0
$0
$0
Blower System
$0
$0
$0
$0
$0
$0
$0
$0
$0
Secondary Clarifier
$0
$0
$0
$0
$0
$0
$0
Membrane Filter
$103,000
$103,000
Nitrification, suspended growth
$0
Tertiary clarification, nitrification
$0
Denitrification, suspended growth
$991,000
Tertiary clarification,
denitrification
$0
Fermenter
$0
$0
$0
$0
$0
Chemical Phosphorus Removal
$1,210,000
$61,500
$61,500
$61,500
$31,000
$61,500
$61,300
Alum Feed System
$0
$0
$0
$0
$0
$0
$0
Denitrification, attached growth
$74,300
$7,430
Sand Filter
$0
$0
$0
$0
Ultrafiltration
$91,400
Reverse Osmosis
$361,000
$341,000
Chlorination
$179,000
$179,000
$179,000
$143,000
$143,000
$143,000
$143,000
$88,200
$89,300
Dechlorination
$50,400
$50,400
$50,400
$50,400
$50,400
$50,400
$50,400
$82,500
$83,500
Effluent Release
$0
$0
$0
$0
$0
$0
$0
$0
$0
Gravity Thickener
$0
$0
$0
$0
$0
$0
$0
$0
$0
Anaerobic Digester
$0
$0
$0
$0
$0
$0
$0
$0
$0
Centrifuge
$84,700
$71,800
$126,000
$72,100
$72,100
$72,100
$70,700
$72,200
$69,800
Sludge Hauling and Landfill
$0
$0
$0
$0
$0
$0
$0
$0
$0
Brine Injection Well
$0
$0
Other Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
Total
$314,000
$301,000
$2,560,000
$327,000
$327,000
$401,000
$475,000
$764,000
$748,000
KP-C-16-003; WA 2^37
1-7
-------
Appendix I: Cost Results by Unit Process
Table 1-7. Total Energy Costs by Detailed Unit Process (2014 $)
Pnni-ss
IamI 1,
AS
IamI 2-1,
\2()
IamI 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nil
Iam I 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
Iam I 5-2,
MliR/RO
Screening and grit removal
$4,700
$4,680
$4,720
$4,690
$4,690
$4,690
$4,680
$4,690
$4,680
Primary clarifier
$1,190
$1,180
$1,210
$1,180
$1,180
$1,180
$1,180
$1,180
$1,180
Activated Sludge
$198,000
$204,000
Biological nutrient removal-3-stage
$592,000
Biological nutrient removal-4-stage
$737,000
$483,000
Biological nutrient removal-5-stage
$635,000
$635,000
$635,000
$541,000
Blower System
$0
$0
$0
$0
$0
$0
$0
$0
$0
Secondary Clarifier
$1,760
$1,590
$1,820
$1,660
$1,660
$1,660
$1,660
Membrane Filter
$319,000
$320,000
Nitrification, suspended growth
$217,000
Tertiary clarification, nitrification
$1,140
Denitrification, suspended growth
$175,000
Tertiary clarification,
denitrification
$1,400
Fermenter
$1,220
$1,220
$1,220
$1,223
$1,220
Chemical Phosphorus Removal
$0
$0
$0
$0
$0
$0
$0
Alum Feed System
$0
$0
$0
$0
$0
$0
$0
Denitrification, attached growth
$174,000
$20,400
Sand Filter
$7,690
$7,690
$7,690
$820
Ultrafiltration
$234,000
Reverse Osmosis
$641,000
$606,000
Chlorination
$13,100
$13,100
$13,100
$13,100
$13,100
$13,100
$13,100
$12,600
$12,600
Dechlorination
$650
$650
$650
$650
$650
$650
$650
$650
$650
Effluent Release
$0
$0
$0
$0
$0
$0
$0
$0
$0
Gravity Thickener
$1,030
$977
$1,130
$975
$975
$975
$972
$975
$965
Anaerobic Digester
$342,320
$306,861
$477,457
$304,875
$304,875
$304,875
$293,400
$304,875
$277,773
Centrifuge
$24,000
$20,500
$34,500
$20,600
$20,600
$20,600
$20,300
$20,600
$20,000
Sludge Hauling and Landfill
$0
$0
$0
$0
$0
$0
$0
$0
$0
Brine Injection Well
$457,000
$457,000
Other Costs
$0
$0
$0
$0
$0
$0
$0
$0
$0
Total
$587,000
$942,000
$1,130,000
$992,000
$1,090,000
$1,170,000
$1,140,000
$2,340,000
$2,240,000
KP-C-16-003; WA 2^37
1-8
-------
Appendix J: LCIA Results by Unit Process
APPENDIX J
LCIA RESULTS BY UNIT PROCESS
KP-C-16-003; WA 2^37
-------
Appendix J: LCIA Results by Unit Process
Appendix J: LCIA Results by Unit Process
This Appendix provides LCIA results by unit process. Table J-l through Table J-12
display the detailed results for the twelve impact categories by unit process on the basis of a
cubic meter of wastewater treated.
KP-C-16-003; WA 2^37
J-l
-------
Appendix J: LCIA Results by Unit Process
Table J-l. Eutrophication Potential Results by Detailed Unit Process (kg N eq/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
Iam I 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nil
Iam I 4-2.
Mlik
Ia-m-I 5-1,
IJ5/KO
Ia-m-I 5-2.
Mlik/k()
Screening and grit removal
1.2E-5
1.2E-5
1.2E-5
1.2E-5
1.2E-5
1.2E-5
1.2E-5
1.2E-5
1.2E-5
Primary clarifier
3.4E-6
3.4E-6
3.5E-6
3.4E-6
3.4E-6
3.3E-6
3.3E-6
3.4E-6
3.3E-6
Activated sludge
5.0E-4
5.1E-4
Secondary clarifier
5.1E-6
4.6E-6
5.2E-6
4.8E-6
4.8E-6
4.8E-6
4.8E-6
Biological nutrient removal-3-stage
1.5E-3
Biological nutrient removal-4-stage
1.8E-3
1.2E-3
Biological nutrient removal-5-stage
1.6E-3
1.6E-3
1.6E-3
1.4E-3
Filtration
2.2E-5
2.2E-5
2.2E-5
2.3E-6
Tertiary clarification,
denitrification
4.2E-6
Tertiary clarification, nitrification
3.5E-6
Chlorination
1.1E-4
1.0E-4
1.0E-4
9.0E-5
9.0E-5
9.0E-5
9.0E-5
6.7E-5
6.7E-5
Dechlorination
4.3E-5
4.3E-5
4.3E-5
4.3E-5
4.3E-5
4.3E-5
4.3E-5
5.1E-5
5.1E-5
Reverse osmosis
1.7E-3
1.6E-3
Denitrification, attached growth
4.5E-4
5.3E-5
Denitrification, suspended growth
4.8E-4
Nitrification, suspended growth
5.5E-4
Ultrafiltration
6.7E-4
Chemical phosphorus removal
2.5E-4
1.3E-5
1.3E-5
1.3E-5
6.4E-6
1.3E-5
6.3E-6
Membrane filter
8.3E-4
8.3E-4
Centrifuge
8.6E-5
7.3E-5
1.3E-4
7.4E-5
7.4E-5
7.4E-5
7.2E-5
7.4E-5
7.1E-5
Sludge hauling and landfill
1.7E-3
1.5E-3
2.6E-3
1.5E-3
1.5E-3
1.5E-3
1.4E-3
1.5E-3
1.4E-3
Anaerobic digester
1.4E-4
1.2E-4
1.7E-4
1.2E-4
1.2E-4
1.2E-4
1.2E-4
1.2E-4
1.1E-4
Fermentation
3.1E-6
3.1E-6
3.1E-6
3.1E-6
3.1E-6
Gravity thickener
2.6E-6
2.5E-6
2.9E-6
2.5E-6
2.5E-6
2.5E-6
2.5E-6
2.5E-6
2.5E-6
Effluent release
0.06
6.5E-3
0.01
3.3E-3
3.3E-3
2.2E-3
3.0E-3
5.9E-4
8.5E-4
Underground injection of brine
1.1E-3
1.1E-3
Total
0.07
9.8E-3
0.02
6.8E-3
6.9E-3
6.1E-3
6.8E-3
7.5E-3
7.5E-3
KP-C-16-003; WA 2^37
J-2
-------
Appendix J: LCIA Results by Unit Process
Table 3-2. Cumulative Energy Demand Results by Detailed Unit Process (MJ/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
IamI 2-2.
AS3
IamI 3-1.
155
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/I)i'iiil
IamI 4-2.
Mlik
1 A-\ i-l 5-1,
IJ5/KO
IamI 5-2.
MI5K/KO
Screening and grit removal
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
0.05
Primary clarifier
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
Activated sludge
2.0
-
2.1
-
-
-
-
-
-
Secondary clarifier
0.02
0.02
0.02
0.02
0.02
0.02
0.02
-
Biological nutrient removal-3-stage
-
6.1
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
7.2
-
5.0
-
-
Biological nutrient removal-5-stage
-
-
-
6.5
-
6.5
-
6.5
5.6
Filtration
-
-
-
0.09
0.09
0.09
-
9.2E-3
-
Tertiary clarification,
denitrification
0.02
Tertiary clarification, nitrification
-
-
0.01
-
-
-
-
-
-
Chlorination
0.35
0.33
0.33
0.29
0.29
0.29
0.29
0.23
0.23
Dechlorination
0.17
0.17
0.17
0.17
0.17
0.17
0.17
0.20
0.20
Reverse osmosis
-
-
-
-
-
-
-
6.9
6.5
Denitrification, attached growth
-
-
-
-
-
2.7
-
0.30
-
Denitrification, suspended growth
-
-
3.8
-
-
-
-
-
-
Nitrification, suspended growth
-
-
2.3
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
2.8
-
Chemical phosphorus removal
-
-
0.79
0.04
0.04
0.04
0.02
0.04
0.02
Membrane filter
-
-
-
-
-
-
3.4
-
3.4
Centrifuge
0.39
0.33
0.57
0.33
0.33
0.33
0.33
0.33
0.32
Sludge hauling and landfill
0.51
0.44
0.88
0.45
0.45
0.45
0.43
0.45
0.43
Anaerobic digester
1.8
1.6
2.5
1.8
1.6
1.6
1.6
1.6
1.5
Fermentation
-
-
-
0.01
0.01
0.01
-
0.01
0.01
Gravity thickener
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
0.01
Effluent release
-
-
-
-
-
-
-
-
-
Underground injection of brine
-
-
-
-
-
-
-
4.7
4.7
Total
5.4
9.1
14
9.7
10
12
11
24
23
KP-C-16-003; WA 2^37
J-3
-------
Appendix J: LCIA Results by Unit Process
Table J-3. Global Warming Potential Results by Detailed Unit Process (kg CO2 eq/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
l.lMl 2-1.
\2()
IamI 2-2.
AS3
l.lMl 3-1.
IS5
IamI 3-2.
Ml (1
l.l-Ml 4-1.
Ii5/I)i'iiii
IamI 4-2.
Mlik
1 .i-\ i-l 5-1,
U5/RO
IamI 5-2,
MI5K/KO
Screening and grit removal
2.7E-3
2.7E-3
2.7E-3
2.7E-3
2.7E-3
2.7E-3
2.7E-3
2.7E-3
2.7E-3
Primary clarifier
1.0E-3
1.0E-3
1.1E-3
1.0E-3
1.0E-3
1.0E-3
1.0E-3
1.0E-3
1.0E-3
Activated sludge
0.14
-
0.21
-
-
-
-
-
-
Secondary clarifier
1.6E-3
1.5E-3
1.6E-3
1.5E-3
1.5E-3
1.5E-3
1.5E-3
-
Biological nutrient removal-3-stage
-
0.49
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
0.68
-
0.66
-
-
Biological nutrient removal-5-stage
-
-
-
0.75
-
0.75
-
0.75
0.69
Filtration
-
-
-
4.5E-3
4.5E-3
4.5E-3
-
4.8E-4
-
Tertiary clarification,
denitrification
1.4E-3
Tertiary clarification, nitrification
-
-
1.2E-3
-
-
-
-
-
-
Chlorination
0.02
0.02
0.02
0.02
0.02
0.02
0.02
0.01
0.01
Dechlorination
9.4E-3
9.4E-3
9.4E-3
9.4E-3
9.4E-3
9.4E-3
9.4E-3
0.01
0.01
Reverse osmosis
-
-
-
-
-
-
-
0.39
0.36
Denitrification, attached growth
-
-
-
-
-
0.12
-
0.01
-
Denitrification, suspended growth
-
-
0.14
-
-
-
-
-
-
Nitrification, suspended growth
-
-
0.13
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
0.15
-
Chemical phosphorus removal
-
-
0.04
2.1E-3
2.1E-3
2.1E-3
1.0E-3
2.1E-3
1.0E-3
Membrane filter
-
-
-
-
-
-
0.19
0.19
Centrifuge
0.02
0.02
0.03
0.02
0.02
0.02
0.02
0.02
0.02
Sludge hauling and landfill
0.07
0.06
0.09
0.06
0.06
0.06
0.06
0.06
0.05
Anaerobic digester
0.19
0.16
0.23
0.16
0.16
0.16
0.15
0.16
0.15
Fermentation
-
-
-
7.4E-4
7.4E-4
7.4E-4
-
7.4E-4
7.4E-4
Gravity thickener
6.5E-4
6.1E-4
7.2E-4
6.1E-4
6.1E-4
6.1E-4
6.1E-4
6.1E-4
6.0E-4
Effluent release
0.07
0.02
0.02
0.01
0.01
6.8E-3
7.0E-3
1.5E-3
3.9E-3
Underground injection of brine
-
-
-
-
-
-
-
0.26
0.26
Total
0.52
0.77
0.92
1.0
0.96
1.1
1.1
1.8
1.8
KP-C-16-003; WA 2^37
J-4
-------
Appendix J: LCIA Results by Unit Process
Table J-4. Acidification Potential Results by Detailed Unit Process (kg SO2 eq/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
Iam I 2-2.
AS3
Iam I 3-1.
155
Iam I 3-2.
Ml (1
Iam I 4-1.
Ii5/l)i-nil
Iam I 4-2.
Mlik
Ia-m-I 5-1,
IJ5/KO
Ia-m-I 5-2.
Mlik/k()
Screening and grit removal
2.1E-4
2.1E-4
2.1E-4
2.1E-4
2.1E-4
2.1E-4
2.1E-4
2.1E-4
2.1E-4
Primary clarifier
5.7E-5
5.7E-5
5.9E-5
5.7E-5
5.7E-5
5.7E-5
5.7E-5
5.7E-5
5.7E-5
Activated sludge
9.0E-3
-
9.2E-3
-
-
-
-
-
-
Secondary clarifier
8.6E-5
7.8E-5
8.8E-5
8.1E-5
8.2E-5
8.2E-5
-
8.2E-5
-
Biological nutrient removal-3-stage
-
0.03
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
0.03
-
0.02
-
-
Biological nutrient removal-5-stage
-
-
-
0.03
-
0.03
-
0.03
0.02
Filtration
-
-
-
3.5E-4
3.5E-4
3.5E-4
-
3.7E-5
-
Tertiary clarification,
denitrification
6.9E-5
Tertiary clarification, nitrification
-
-
5.8E-5
-
-
-
-
-
-
Chlorination
6.5E-4
6.4E-4
6.4E-4
6.3E-4
6.3E-4
6.3E-4
6.3E-4
5.9E-4
5.9E-4
Dechlorination
6.0E-4
6.0E-4
6.0E-4
6.0E-4
6.0E-4
6.0E-4
6.0E-4
5.9E-4
5.9E-4
Reverse osmosis
-
-
-
-
-
-
-
0.03
0.03
Denitrification, attached growth
-
-
-
-
-
7.9E-3
-
9.2E-4
-
Denitrification, suspended growth
-
-
8.0E-3
-
-
-
-
-
-
Nitrification, suspended growth
-
-
9.8E-3
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
0.01
-
Chemical phosphorus removal
-
-
7.5E-4
3.8E-5
3.8E-5
3.8E-5
1.9E-5
3.8E-5
1.9E-5
Membrane filter
-
-
-
-
-
-
0.01
-
0.01
Centrifuge
1.1E-3
9.5E-4
1.6E-3
9.6E-4
9.6E-4
9.6E-4
9.4E-4
9.6E-4
9.2E-4
Sludge hauling and landfill
-
-
-
-9.6E-4
-9.7E-4
-9.7E-4
-9.8E-4
-9.7E-4
-9.3E-4
Anaerobic digester
2.4E-3
2.1E-3
3.0E-3
2.2E-3
2.0E-3
2.0E-3
2.0E-3
2.0E-3
2.0E-3
Fermentation
-
-
-
5.6E-5
5.6E-5
5.6E-5
-
5.6E-5
5.5E-5
Gravity thickener
4.7E-5
4.5E-5
5.2E-5
4.5E-5
4.5E-5
4.5E-5
4.4E-5
4.5E-5
4.4E-5
Effluent release
-
-
-
-
-
-
-
-
-
Underground injection of brine
-
-
-
-
-
-
-
0.02
0.02
Total
0.01
0.03
0.03
0.03
0.04
0.04
0.04
0.09
0.09
KP-C-16-003; WA 2^37
J-5
-------
Appendix J: LCIA Results by Unit Process
Table J-5. Fossil Depletion Results by Detailed Unit Process (kg oil eq/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
IamI 2-2.
AS3
IamI 3-1.
155
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/I)i'iiil
IamI 4-2.
Mlik
1 a-\ i-l 5-1,
IJ5/KO
IamI 5-2.
MI5K/KO
Screening and grit removal
1.1E-3
1.1E-3
1.1E-3
1.1E-3
1.1E-3
1.1E-3
1.1E-3
1.1E-3
1.1E-3
Primary clarifier
3.1E-4
3.0E-4
3.1E-4
3.0E-4
3.0E-4
3.0E-4
3.0E-4
3.0E-4
3.0E-4
Activated sludge
0.05
-
0.05
-
-
-
-
-
-
Secondary clarifier
4.6E-4
4.2E-4
4.7E-4
4.4E-4
4.4E-4
4.4E-4
-
4.4E-4
-
Biological nutrient removal-3-stage
-
0.14
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
0.16
0.11
-
-
Biological nutrient removal-5-stage
-
-
-
0.15
0.15
-
0.15
0.12
Filtration
-
-
-
1.9E-3
1.9E-3
1.9E-3
-
2.1E-4
-
Tertiary clarification,
denitrification
-
-
3.8E-4
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
3.2E-4
-
-
-
-
-
-
Chlorination
6.0E-3
5.7E-3
5.7E-3
5.2E-3
5.2E-3
5.2E-3
5.2E-3
4.2E-3
4.3E-3
Dechlorination
3.6E-3
3.6E-3
3.6E-3
3.6E-3
3.6E-3
3.6E-3
3.6E-3
4.1E-3
4.1E-3
Reverse osmosis
-
-
-
-
-
-
-
0.15
0.14
Denitrification, attached growth
-
-
-
-
-
0.06
-
6.7E-3
-
Denitrification, suspended growth
-
-
0.09
-
-
-
-
-
-
Nitrification, suspended growth
-
-
0.05
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
0.06
-
Chemical phosphorus removal
-
-
0.01
6.3E-4
6.3E-4
6.3E-4
3.2E-4
6.3E-4
3.2E-4
Membrane filter
-
-
-
-
-
-
0.08
-
0.08
Centrifuge
8.8E-3
7.5E-3
0.01
7.6E-3
7.5E-3
7.5E-3
7.4E-3
7.5E-3
7.2E-3
Sludge hauling and landfill
0.01
9.2E-3
0.02
9.6E-3
9.5E-3
9.5E-3
9.1E-3
9.5E-3
9.0E-3
Anaerobic digester
0.04
0.04
0.06
0.04
0.04
0.04
0.04
0.04
0.03
Fermentation
-
-
-
2.8E-4
2.8E-4
2.8E-4
-
2.8E-4
2.8E-4
Gravity thickener
2.4E-4
2.3E-4
2.7E-4
2.3E-4
2.3E-4
2.3E-4
2.3E-4
2.3E-4
2.2E-4
Effluent release
-
-
-
-
-
-
-
-
-
Underground injection of brine
-
-
-
-
-
-
-
0.10
0.10
Total
0.12
0.20
0.30
0.22
0.23
0.28
0.25
0.54
0.51
KP-C-16-003; WA 2^37
J-6
-------
Appendix J: LCIA Results by Unit Process
Table J-6. Smog Formation Potential Results by Detailed Unit Process (kg O3 eq/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
IamI 2-2.
AS3
IamI 3-1.
155
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/I)i'iiil
IamI 4-2.
Mlik
1 a-\ i-l 5-1,
IJ5/KO
IamI 5-2.
MI5K/KO
Screening and grit removal
1.6E-3
1.6E-3
1.6E-3
1.6E-3
1.6E-3
1.6E-3
1.6E-3
1.6E-3
1.6E-3
Primary clarifier
4.5E-4
4.5E-4
4.6E-4
4.5E-4
4.5E-4
4.5E-4
4.5E-4
4.5E-4
4.5E-4
Activated sludge
0.07
-
0.07
-
-
-
-
-
-
Secondary clarifier
6.8E-4
6.2E-4
7.0E-4
6.5E-4
6.5E-4
6.5E-4
-
6.5E-4
-
Biological nutrient removal-3-stage
-
0.21
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
0.25
-
0.17
-
-
Biological nutrient removal-5-stage
-
-
-
0.22
-
0.22
-
0.22
0.19
Filtration
-
-
-
2.7E-3
2.7E-3
2.7E-3
-
2.9E-4
-
Tertiary clarification,
denitrification
-
-
5.5E-4
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
4.7E-4
-
-
-
-
-
-
Chlorination
5.1E-3
5.0E-3
5.0E-3
4.9E-3
4.9E-3
4.9E-3
4.9E-3
4.6E-3
4.6E-3
Dechlorination
5.0E-3
5.0E-3
5.0E-3
5.0E-3
5.0E-3
5.0E-3
5.0E-3
5.3E-3
5.3E-3
Reverse osmosis
-
-
-
-
-
-
-
0.22
0.21
Denitrification, attached growth
-
-
-
-
-
0.06
-
7.1E-3
-
Denitrification, suspended growth
-
-
0.06
-
-
-
-
-
-
Nitrification, suspended growth
-
-
0.08
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
0.08
-
Chemical phosphorus removal
-
-
3.0E-3
1.5E-4
1.5E-4
1.5E-4
7.6E-5
1.5E-4
7.5E-5
Membrane filter
-
-
-
-
-
-
0.11
-
0.11
Centrifuge
8.6E-3
7.3E-3
0.01
7.4E-3
7.4E-3
7.4E-3
7.2E-3
7.4E-3
7.1E-3
Sludge hauling and landfill
-
-
-7.1E-3
-5.9E-3
-5.9E-3
-5.9E-3
-6.0E-3
-5.9E-3
-5.7E-3
Anaerobic digester
0.05
0.04
0.05
0.04
0.04
0.04
0.04
0.04
0.04
Fermentation
-
-
-
4.3E-4
4.3E-4
4.3E-4
-
4.3E-4
4.3E-4
Gravity thickener
3.7E-4
3.5E-4
4.0E-4
3.5E-4
3.5E-4
3.5E-4
3.4E-4
3.5E-4
3.4E-4
Effluent release
-
-
-
-
-
-
-
-
-
Underground injection of brine
-
-
-
-
-
4.3E-4
-
0.16
0.16
Total
0.14
0.27
0.29
0.28
0.30
0.34
0.33
0.75
0.72
KP-C-16-003; WA 2^37
J-7
-------
Appendix J: LCIA Results by Unit Process
Table 3-1. Human Health- Particulate Matter Formation Potential Results by Detailed Unit Process (kg PM2.5 eq/m3
Wastewater Treated)
Pnni-ss
Ia-m-I 1,
AS
Ia-m-I 2-1.
A2()
Ia-m-I 2-2.
AS3
Ia-m-I 3-1.
155
Ia-m-I 3-2.
Ml (1
Ia-m-I 4-1.
Ii5/l)i-iiil
Ia-m-I 4-2.
Mlik
1 a-\ i-l 5-1,
IJ5/KO
Ia-m-I 5-2.
MI5K/KO
Screening and grit removal
2.4E-5
2.4E-5
2.4E-5
2.4E-5
2.4E-5
2.4E-5
2.4E-5
2.4E-5
2.4E-5
Primary clarifier
6.5E-6
6.5E-6
6.6E-6
6.5E-6
6.5E-6
6.5E-6
6.5E-6
6.5E-6
6.4E-6
Activated sludge
1.0E-3
-
1.0E-3
-
-
-
-
-
-
Secondary clarifier
9.8E-6
8.9E-6
1.0E-5
9.2E-6
9.3E-6
9.3E-6
-
9.3E-6
-
Biological nutrient removal-3-stage
-
3.0E-3
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
3.6E-3
-
2.5E-3
-
-
Biological nutrient removal-5-stage
-
-
-
3.2E-3
-
3.2E-3
-
3.2E-3
2.7E-3
Filtration
-
-
-
3.9E-5
3.9E-5
3.9E-5
-
4.1E-6
-
Tertiary clarification,
denitrification
-
-
7.9E-6
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
6.6E-6
-
-
-
-
-
-
Chlorination
7.2E-5
7.1E-5
7.1E-5
7.0E-5
7.0E-5
7.0E-5
7.0E-5
6.6E-5
6.6E-5
Dechlorination
7.0E-5
7.0E-5
7.0E-5
7.0E-5
7.0E-5
7.0E-5
7.0E-5
7.1E-5
7.1E-5
Reverse osmosis
-
-
-
-
-
-
-
3.2E-3
3.1E-3
Denitrification, attached growth
-
-
-
-
-
8.8E-4
-
1.0E-4
-
Denitrification, suspended growth
-
-
8.9E-4
-
-
-
-
-
-
Nitrification, suspended growth
-
-
1.1E-3
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
1.2E-3
-
Chemical phosphorus removal
-
-
6.6E-5
3.3E-6
3.3E-6
3.3E-6
1.7E-6
3.3E-6
1.7E-6
Membrane filter
-
-
-
-
-
-
1.6E-3
-
1.6E-3
Centrifuge
1.3E-4
1.1E-4
1.8E-4
1.1E-4
1.1E-4
1.1E-4
1.1E-4
1.1E-4
1.0E-4
Sludge hauling and landfill
-
-
-1.5E-4
-1.1E-4
-1.1E-4
-1.1E-4
-1.1E-4
-1.1E-4
-1.1E-4
Anaerobic digester
1.8E-4
1.6E-4
2.3E-4
1.7E-4
1.6E-4
1.6E-4
1.6E-4
1.6E-4
1.5E-4
Fermentation
-
-
-
6.2E-6
6.2E-6
6.2E-6
-
6.2E-6
6.2E-6
Gravity thickener
5.3E-6
5.0E-6
5.8E-6
5.0E-6
5.0E-6
5.0E-6
5.0E-6
5.0E-6
4.9E-6
Effluent release
-
-
-
-
-
-
-
-
-
Underground injection of brine
-
-
-
-
-
-
-
2.3E-3
2.3E-3
Total
1.5E-3
3.4E-3
3.5E-3
3.6E-3
3.9E-3
4.5E-3
4.4E-3
0.01
0.01
KP-C-16-003; WA 2^37
J-8
-------
Appendix J: LCIA Results by Unit Process
Table J-8. Ozone Depletion Potential Results by Detailed Unit Process (kg CFC-11 eq/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
\2()
IamI 2-2.
AS3
IamI 3-1.
IS5
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/I)i'iiii
IamI 4-2.
Mlik
1 a-\ i-l 5-1,
IJ5/KO
IamI 5-2.
MI5K/KO
Screening and grit removal
1.8E-9
1.8E-9
1.8E-9
1.8E-9
1.8E-9
1.8E-9
1.8E-9
1.8E-9
1.8E-9
Primary clarifier
5.0E-10
5.0E-10
5.1E-10
5.0E-10
5.0E-10
5.0E-10
5.0E-10
5.0E-10
5.0E-10
Activated sludge
6.1E-7
-
3.9E-7
-
-
-
-
-
-
Secondary clarifier
7.6E-10
6.9E-10
7.8E-10
7.1E-10
7.2E-10
7.2E-10
-
7.2E-10
-
Biological nutrient removal-3-stage
-
2.6E-6
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
2.7E-6
-
6.4E-6
-
-
Biological nutrient removal-5-stage
-
-
-
6.6E-6
-
6.6E-6
-
6.6E-6
6.5E-6
Filtration
-
-
-
3.0E-9
3.0E-9
3.0E-9
-
3.2E-10
-
Tertiary clarification,
denitrification
-
-
6.1E-10
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
5.1E-10
-
-
-
-
-
-
Chlorination
2.6E-8
2.5E-8
2.5E-8
2.1E-8
2.1E-8
2.1E-8
2.1E-8
1.5E-8
1.5E-8
Dechlorination
6.0E-9
6.0E-9
6.0E-9
6.0E-9
6.0E-9
6.0E-9
6.0E-9
6.7E-9
6.7E-9
Reverse osmosis
-
-
-
-
-
-
-
2.7E-7
2.5E-7
Denitrification, attached growth
-
-
-
-
-
7.4E-8
-
8.5E-9
-
Denitrification, suspended growth
-
-
8.2E-8
-
-
-
-
-
-
Nitrification, suspended growth
-
-
8.6E-8
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
1.1E-7
-
Chemical phosphorus removal
-
-
1.5E-8
7.7E-10
7.7E-10
7.7E-10
3.9E-10
7.7E-10
3.8E-10
Membrane filter
-
-
-
-
-
-
1.3E-7
-
1.3E-7
Centrifuge
1.1E-8
9.1E-9
1.5E-8
9.2E-9
9.1E-9
9.1E-9
9.0E-9
9.1E-9
8.8E-9
Sludge hauling and landfill
4.9E-9
4.4E-9
1.2E-8
4.9E-9
4.8E-9
4.8E-9
4.4E-9
4.8E-9
4.6E-9
Anaerobic digester
5.9E-7
4.9E-7
6.5E-7
4.7E-7
4.7E-7
4.7E-7
4.8E-7
4.7E-7
4.5E-7
Fermentation
4.8E-10
4.8E-10
4.8E-10
-
4.8E-10
4.8E-10
Gravity thickener
4.1E-10
3.9E-10
4.5E-10
3.9E-10
3.9E-10
3.9E-10
3.9E-10
3.9E-10
3.8E-10
Effluent release
2.6E-6
6.9E-7
6.7E-7
5.2E-7
5.2E-7
2.5E-7
2.6E-7
5.5E-8
1.4E-7
Underground injection of brine
-
-
-
-
-
-
-
1.8E-7
1.8E-7
Total
3.9E-6
3.8E-6
2.0E-6
7.6E-6
3.7E-6
7.4E-6
7.3E-6
7.7E-6
7.7E-6
KP-C-16-003; WA 2^37
J-9
-------
Appendix J: LCIA Results by Unit Process
Table J-9. Water Depletion Results by Detailed Unit Process (m3H20/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
IamI 2-2.
AS3
IamI 3-1.
155
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/I)i'iiil
IamI 4-2.
Mlik
1 a-\ i-l 5-1,
IJ5/KO
IamI 5-2.
MI5K/KO
Screening and grit removal
8.2E-6
8.1E-6
8.2E-6
8.2E-6
8.2E-6
8.2E-6
8.1E-6
8.2E-6
8.1E-6
Primary clarifier
5.9E-6
5.8E-6
6.0E-6
5.8E-6
5.8E-6
5.8E-6
5.8E-6
5.8E-6
5.8E-6
Activated sludge
3.6E-4
-
3.8E-4
-
-
-
-
-
-
Secondary clarifier
9.4E-6
9.1E-6
9.5E-6
9.2E-6
9.2E-6
9.2E-6
-
9.2E-6
-
Biological nutrient removal-3-stage
-
1.1E-3
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
1.3E-3
-
8.7E-4
-
-
Biological nutrient removal-5-stage
-
-
-
1.2E-3
-
1.2E-3
-
1.2E-3
9.7E-4
Filtration
-
-
-
1.6E-5
1.6E-5
1.6E-5
-
1.7E-6
-
Tertiary clarification,
denitrification
-
-
8.7E-6
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
8.3E-6
-
-
-
-
-
-
Chlorination
1.7E-4
1.6E-4
1.6E-4
1.3E-4
1.3E-4
1.3E-4
1.3E-4
9.0E-5
9.1E-5
Dechlorination
3.7E-5
3.7E-5
3.7E-5
3.7E-5
3.7E-5
3.7E-5
3.7E-5
4.9E-5
4.9E-5
Reverse osmosis
-
-
-
-
-
-
-
1.7E-3
1.6E-3
Denitrification, attached growth
-
-
-
-
-
3.5E-4
-
4.0E-5
-
Denitrification, suspended growth
-
-
4.1E-4
-
-
-
-
-
-
Nitrification, suspended growth
-
-
4.1E-4
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
1.4E-3
-
Chemical phosphorus removal
-
-
2.4E-3
1.2E-4
1.2E-4
1.2E-4
6.0E-5
1.2E-4
6.0E-5
Membrane filter
-
-
-
-
-
-
6.7E-4
-
6.7E-4
Centrifuge
6.3E-5
5.3E-5
9.1E-5
5.4E-5
5.4E-5
5.4E-5
5.3E-5
5.4E-5
5.1E-5
Sludge hauling and landfill
9.0E-5
7.8E-5
1.5E-4
8.0E-5
8.0E-5
8.0E-5
7.7E-5
8.0E-5
7.6E-5
Anaerobic digester
5.7E-5
5.1E-5
7.4E-5
5.5E-5
5.1E-5
5.1E-5
5.0E-5
5.1E-5
4.8E-5
Fermentation
-
-
-
2.6E-6
2.6E-6
2.6E-6
-
2.6E-6
2.6E-6
Gravity thickener
2.4E-6
2.3E-6
2.7E-6
2.3E-6
2.3E-6
2.3E-6
2.3E-6
2.3E-6
2.2E-6
Effluent release
-
-
-
-
-
-
-
-
-
Underground injection of brine
-
-
-
-
-
-
-
0.18
0.17
Total
8.0E-4
1.5E-3
4.1E-3
1.7E-3
1.8E-3
2.0E-3
2.0E-3
0.19
0.17
KP-C-16-003; WA 2^37
J-10
-------
Appendix J: LCIA Results by Unit Process
Table J-10. Human Health-Cancer Results by Detailed Unit Process (CTUh/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
IamI 2-2.
AS3
IamI 3-1.
155
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/l)i-nil
IamI 4-2.
Mlik
1 A'\ i-l 5-1,
IJ5/KO
IamI 5-2.
MI5K/KO
Screening and grit removal
1.1E-11
1.1E-11
1.1E-11
1.1E-11
1.1E-11
1.1E-11
1.1E-11
1.1E-11
1.1E-11
Primary clarifier
5.0E-12
4.9E-12
5.1E-12
4.9E-12
4.9E-12
4.9E-12
4.9E-12
4.9E-12
4.9E-12
Activated sludge
4.8E-10
-
5.0E-10
-
-
-
-
-
-
Secondary clarifier
7.5E-12
7.1E-12
7.6E-12
7.2E-12
7.2E-12
7.2E-12
-
7.2E-12
-
Biological nutrient removal-3-stage
-
1.4E-9
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
1.7E-9
-
1.2E-9
-
-
Biological nutrient removal-5-stage
-
-
-
1.5E-9
-
1.5E-9
-
1.5E-9
1.3E-9
Filtration
-
-
-
1.9E-11
1.9E-11
1.9E-11
-
2.0E-12
-
Tertiary clarification,
denitrification
-
-
6.6E-12
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
6.0E-12
-
-
-
-
-
-
Chlorination
1.9E-10
1.4E-10
1.4E-10
1.2E-10
1.2E-10
1.2E-10
1.2E-10
8.4E-11
8.5E-11
Dechlorination
5.4E-11
5.4E-11
5.4E-11
5.4E-11
5.4E-11
5.4E-11
5.4E-11
7.3E-11
7.4E-11
Reverse osmosis
-
-
-
-
-
-
-
1.7E-9
1.6E-9
Denitrification, attached growth
-
-
-
-
-
4.8E-10
-
5.6E-11
-
Denitrification, suspended growth
-
-
5.6E-10
-
-
-
-
-
-
Nitrification, suspended growth
-
-
5.6E-10
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
7.6E-10
-
Chemical phosphorus removal
-
-
4.9E-9
2.4E-10
2.4E-10
2.4E-10
1.2E-10
2.4E-10
1.2E-10
Membrane filter
-
-
-
-
-
-
8.1E-10
-
8.1E-10
Centrifuge
8.8E-11
7.5E-11
1.3E-10
7.6E-11
7.6E-11
7.6E-11
7.4E-11
7.6E-11
7.3E-11
Sludge hauling and landfill
2.6E-10
2.3E-10
3.8E-10
2.4E-10
2.5E-10
2.4E-10
2.7E-10
2.8E-10
2.8E-10
Anaerobic digester
9.0E-11
8.1E-11
1.2E-10
8.7E-11
8.1E-11
8.1E-11
7.9E-11
8.1E-11
7.6E-11
Fermentation
-
-
-
3.1E-12
3.1E-12
3.1E-12
-
3.1E-12
3.1E-12
Gravity thickener
2.7E-12
2.6E-12
3.0E-12
2.6E-12
2.6E-12
2.6E-12
2.6E-12
2.6E-12
2.5E-12
Effluent release
3.1E-9
3.1E-9
2.5E-9
2.1E-9
1.5E-9
2.4E-9
1.0E-9
4.0E-10
1.7E-10
Underground injection of brine
-
-
-
-
-
-
-
1.1E-9
1.1E-9
Total
4.3E-9
5.1E-9
9.9E-9
4.5E-9
4.1E-9
5.2E-9
3.7E-9
6.4E-9
5.7E-9
KP-C-16-003; WA 2^37
J-ll
-------
Appendix J: LCIA Results by Unit Process
Table J-ll. Human Health-NonCancer Results by Detailed Unit Process (CTUh/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
A2()
IamI 2-2.
AS3
IamI 3-1.
155
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/I)i'iiil
IamI 4-2.
Mlik
1 a-\ i-l 5-1,
IJ5/KO
IamI 5-2.
MI5K/KO
Screening and grit removal
1.1E-10
1.1E-10
1.1E-10
1.1E-10
1.1E-10
1.1E-10
1.1E-10
1.1E-10
1.1E-10
Primary clarifier
6.1E-11
6.0E-11
6.1E-11
6.0E-11
6.0E-11
6.0E-11
6.0E-11
6.0E-11
6.0E-11
Activated sludge
4.8E-9
-
4.9E-9
-
-
-
-
-
-
Secondary clarifier
9.3E-11
8.9E-11
9.4E-11
9.1E-11
9.1E-11
9.1E-11
-
9.1E-11
-
Biological nutrient removal-3-stage
-
1.4E-8
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
1.7E-8
-
1.2E-8
-
-
Biological nutrient removal-5-stage
-
-
-
1.5E-8
-
1.5E-8
-
1.5E-8
1.3E-8
Filtration
-
-
-
1.8E-10
1.8E-10
1.8E-10
-
2.0E-11
-
Tertiary clarification,
denitrification
-
-
8.4E-11
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
7.8E-11
-
-
-
-
-
-
Chlorination
2.0E-9
1.6E-9
1.6E-9
1.3E-9
1.3E-9
1.3E-9
1.3E-9
9.2E-10
9.3E-10
Dechlorination
9.6E-10
9.6E-10
9.6E-10
9.6E-10
9.6E-10
9.6E-10
9.6E-10
1.6E-9
1.6E-9
Reverse osmosis
-
-
-
-
-
-
-
1.6E-8
1.5E-8
Denitrification, attached growth
-
-
-
-
-
4.5E-9
-
5.3E-10
-
Denitrification, suspended growth
-
-
5.1E-9
-
-
-
-
-
-
Nitrification, suspended growth
-
-
5.4E-9
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
1.1E-8
-
Chemical phosphorus removal
-
-
1.2E-8
5.8E-10
5.8E-10
5.8E-10
3.0E-10
5.8E-10
2.9E-10
Membrane filter
-
-
-
-
-
-
8.0E-9
-
8.0E-9
Centrifuge
9.3E-10
7.9E-10
1.3E-9
8.0E-10
8.0E-10
8.0E-10
7.8E-10
8.0E-10
7.7E-10
Sludge hauling and landfill
4.5E-9
4.2E-9
5.8E-9
4.9E-9
5.3E-9
4.9E-9
6.3E-9
6.6E-9
6.7E-9
Anaerobic digester
2.1E-9
1.9E-9
2.9E-9
2.1E-9
1.9E-9
1.9E-9
1.8E-9
1.9E-9
1.8E-9
Fermentation
-
-
-
3.2E-11
3.2E-11
3.2E-11
-
3.2E-11
3.2E-11
Gravity thickener
2.9E-11
2.7E-11
3.2E-11
2.7E-11
2.7E-11
2.7E-11
2.7E-11
2.7E-11
2.6E-11
Effluent release
1.0E-7
1.0E-7
1.0E-7
7.6E-8
6.2E-8
7.6E-8
1.9E-8
1.1E-8
2.1E-9
Underground injection of brine
-
-
-
-
-
-
-
1.1E-8
1.1E-8
Total
1.2E-7
1.3E-7
1.4E-7
1.0E-7
9.0E-8
1.1E-7
5.0E-8
7.7E-8
6.1E-8
KP-C-16-003; WA 2^37
J-12
-------
Appendix J: LCIA Results by Unit Process
Table J-12. Ecotoxicity Results by Detailed Unit Process (CTUe/m3 Wastewater Treated)
Pnni-ss
IamI 1.
AS
IamI 2-1.
\2()
IamI 2-2.
AS3
IamI 3-1.
IS5
IamI 3-2.
Ml (1
IamI 4-1.
Ii5/I)i'iiii
IamI 4-2.
Mlik
1 a-\ i-l 5-1,
U5/RO
IamI 5-2.
Mlik/R()
Screening and grit removal
0.59
0.58
0.59
0.59
0.59
0.59
0.58
0.59
0.58
Primary clarifier
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.19
0.19
Activated sludge
25
-
26
-
-
-
-
-
-
Secondary clarifier
0.29
0.27
0.29
0.28
0.28
0.28
-
0.28
-
Biological nutrient removal-3-stage
-
74
-
-
-
-
-
-
-
Biological nutrient removal-4-stage
-
-
-
-
88
-
61
-
-
Biological nutrient removal-5-stage
-
-
-
80
-
80
-
80
68
Filtration
-
-
-
1.0
1.0
1.0
-
0.11
-
Tertiary clarification,
denitrification
-
-
0.24
-
-
-
-
-
-
Tertiary clarification, nitrification
-
-
0.21
-
-
-
-
-
-
Chlorination
5.2
4.9
4.9
4.3
4.3
4.3
4.3
3.2
3.2
Dechlorination
2.1
2.1
2.1
2.1
2.1
2.1
2.1
2.5
2.6
Reverse osmosis
-
-
-
-
-
-
-
83
78
Denitrification, attached growth
-
-
-
-
-
23
-
2.7
-
Denitrification, suspended growth
-
-
25
-
-
-
-
-
-
Nitrification, suspended growth
-
-
28
-
-
-
-
-
-
Ultrafiltration
-
-
-
-
-
-
-
34
-
Chemical phosphorus removal
-
-
14
0.68
0.68
0.68
0.35
0.68
0.34
Membrane filter
-
-
-
-
-
-
42
-
42
Centrifuge
3.5
3.0
5.1
3.0
3.0
3.0
3.0
3.0
2.9
Sludge hauling and landfill
11
11
12
14
14
14
17
18
18
Anaerobic digester
7.3
6.4
9.7
7.0
6.4
6.4
6.2
6.4
6.0
Fermentation
-
-
-
0.16
0.16
0.16
-
0.16
0.16
Gravity thickener
0.14
0.13
0.15
0.13
0.13
0.13
0.13
0.13
0.13
Effluent release
2.8E+2
2.8E+2
2.8E+2
1.6E+2
1.6E+2
1.6E+2
72
25
6.0
Underground injection of brine
-
-
-
-
-
-
-
57
57
Total
3.4E+2
3.9E+2
4.1E+2
2.7E+2
2.8E+2
2.9E+2
2.1E+2
3.2E+2
2.9E+2
KP-C-16-003; WA 2^37
J-13
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SEPA
United States
Environmental Protection
Agency
Errata to:
Life Cycle and Cost Assessments of
Nutrient Removal Technologies in
Wastewater Treatment Plants
Prepared for:
U.S. Environmental Protection Agency
Standards and Health Protection Division
Office of Water, Office of Science and Technology
1200 Pennsylvania Avenue NW (4305T)
Washington, DC 20460
Prepared by:
Eastern Research Group, Inc.
110 Hartwell Ave
Lexington, MA 02421
June 2023
EPA 832-R-21-006ES
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Errata
Errata
ERG identified an error in Appendix F of the Life Cycle and Cost Assessments of
Nutrient Removal Technologies in Wastewater Treatment Plants (EPA 832-R-21-006), dated
August 2021. Equation F-3, the equation used to calculate nitrous oxide (N20) emissions from
wastewater treatment processes, included an incorrect molecular weight conversion factor of N
to N20 of 44/14. The correct conversation factor is 44/28.
This error only affects N20 emission from biological treatment. The corrected emissions
are half as much as those presented in the report, as shown in Table 1 below. Emissions of N20
only affect the global warming potential (GWP) impact category but are reflected in all related
charts and discussion (Figures 6-5, 8-1 and 9-3 and Tables 8-1 and 8-3). Figure 1 compares the
GWP impact of treatment systems before and after correction of the N20 conversion factor
(Figure 6-5 in the report).
Table 1. Comparison of N2O Emissions from Biological Treatment
System
C onli^ui'iitioii
I.CM'I
VO Kmillcd by Process (k« VO/yr)
()ri»in:il Kslimitle'
Corrected Kstiniiile
1
6.6E+02
3.3E+02
2-1
2.9E+03
1.5E+03
2-2
3.9E+02
1.9E+02
3-1
7.8E+03
3.9E+03
3-2
3.0E+03
1.5E+03
4-1
8.2E+03
4.1E+03
4-2
7.7E+03
3.9E+03
5-1
7.8E+03
3.9E+03
5-2
7.7E+03
3.9E+03
a - Estimates included in Table F-2 of Life Cycle and Cost Assessments of
Nutrient Removal Technologies in Wastewater Treatment Plants (UPA 832-
R-21-006.
i
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Errata
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Errata
Because the error affected the calculation of biological treatment emissions, which are included
for all systems, it has a limited effect on the comparative results between systems. Correction of the
error alters the height of the biological treatment bars of each system. Prior to correction of the error,
N20 emissions from biological treatment contributed between 0.8% and 15% of total GWP emissions.
• The largest contribution of N2O to GWP is observed for treatment levels 3-1, 4-1, and 4-2 (14-
15%). Using the updated conversion factor the contribution of N2O to GWP drops to between 7
and 8%.
• More moderate contributions are observed for treatment levels 2-1, 3-2, 5-1 and 5-2 (6-8%).
Using the updated conversion factor the contribution of N2O to GWP drops to between 3 and
4%.
• The smallest contribution of N2O to GWP is observed for treatment levels 1 and 2-2 (0.8-3%).
Using the updated conversion factor the contribution of N2O to GWP drops to between 0.4 and
1.3%.
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