Post on 06-Apr-2018
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
A Proactive Wastewater Treatment Approach to
Protecting Water Supply
Texas Association of Clean Water AgenciesSeptember 25, 2009
Authors: Dolan McKnight, Bruce Cole, Jared Thorpe, Jennafer Covington, and Felicia Wyatt
NTMWD & CH2M HILL
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Project Overview
Provide a tool to assist NTMWD staff in evaluation of system improvements for portion of the Upper East Fork system served by Wilson Creek RWWTP—Expand existing WWTP or construct new WWTP?
—More economical to transfer wastewater between interceptors or parallel?
—Scalping plant or transmission of treated water from Wilson Creek RWWTP to customers?
—System impact for up to five prospective future customers?
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Agenda
VOYAGE™ OverviewTreatment ApproachModel ScenariosInput DataScenario ResultsComments and Questions
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
VOYAGE™ Provides Decision Support for Water Management
Large Scale Decision Models—Times steps: 1 week, 1 month, 1 year—Multiple year simulation runs—Ideal for master planning applications
Object-oriented—Flexible configurations—Customized level of detail
Dynamic Simulation—Time dependent variables
Advanced Optimization Tools
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
VOYAGE™ Allows Analysis of“what if” Scenarios
Varying demands—Population changes
Varying supplies—Weather patterns—Changes in water supply
sources
Varying costs—Alternative technologies—Infrastructure requirements—Rate changes
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VOYAGE™ Model Structure
Multilayered approach
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VOYAGE™ Data Sources
Existing Information—Master Plans—Existing infrastructure—Operating data
Projections—Population—Usage behavior
Component Model Outputs—Spreadsheets—EPANET—InfoWorks—BioWin
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VOYAGE™ Resource System Balances
Water Cycle Components—Demands—Supplies—Treatment—Reuse—Storage—Transmission
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VOYAGE™ Performance Analysis
System Economics—CAPEX—OPEX—Life Cycle Cost
Environmental Criteria—Liquid, gas, and solids
releases—Ecological impacts
Social Criteria—Public health protection—Traffic—Cultural heritage—Political imperatives
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VOYAGE™ Optimization & Decision SupportEvaluate numerous alternativesOptimize multiple parameters simultaneouslyFind the best combination of decisionsAdvanced optimization algorithmsPowerful communication tool—Customizable graphical
interface—Animation capabilities
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VOYAGE™ Water Management Model Typical Example
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Agenda
Voyage OverviewTreatment ApproachModel ScenariosInput DataScenario ResultsComments and Questions
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
General Approach to Treatment
Consider multiple water quality scenarios in receiving reservoir with varying levels of stringency—Total Organic Carbon (TOC) —Phosphorus
Use TOC as an indicator parameter for organic contaminants of emerging concern and organic loading
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
General Approach to Treatment
Add advanced water treatment (AWT) processes to —maintain effluent TOC load equivalent to 48-mgd
secondary treatment level at existing plant• For example, assuming 16 mgd expansion, AWT train
removing 50% of secondary effluent TOC would be sized at 16 mgd/50% = 32 mgd
—maintain phosphorus loading rate to meet potential future requirements which vary by scenario
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Performance of AWT Processes Treating Secondary Effluent
Process TOC Removal*
TP Removal*
Comments
Metal Salt Clarification 40-50% 70-80% Alum or ferric salts
Lime Clarification 50-60% 80-90% Requires recarbonation
PAC Adsorption 60-70% 0% In combination with chemical clarification
Granular Media Filtration 20-30% 50-60% After chemical clarification
Membrane Filtration 20-30% 70-80% After chemical clarification
GAC Adsorption 50-60% 0% After chemical clarif. and either GMF or MF
Ozonation 30-40% 0% In comb. with dwnstrm biological filtration
Reverse Osmosis >90% >90% After chemical clarification & MF
UV/Hydrogen Peroxide 0% 0% Targets very specific compds (e.g. NDMA, dioxane)
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Performance of Alternative Treatment Trains Treating Secondary Effluent
Alt. Treatment Train TOC Removal* TP Removal*1 Metal Salt Clarification & Granular Media Filtration 52-65% 85-92%
2 Lime Clarification & Granular Media Filtration 60-72% 90-96%
3 Metal Salt Clarification with PAC Addition & GMF 68-79% 85-92%
4 Lime Clarifica., PAC Addition, Recarbonation & GMF
68-79% 90-96%
5 Metal Salt Clarification, Ozonation, and GMF 58-70% 85-92%
6 Lime Clarifica., Recarbonation, Ozonation & GMF 65-76% 90-96%
7-10 Replace GMF with Membrane Filtration in Alts. 1-4 +0% rel. to GMF +20% rel. to GMF
11-20 Add GAC post treatment to Alts. 1-10 +50-60% +0%
21-24 Add RO to Alts. 7-10 +90% +90%
25-28 Add UV/Hydrogen Peroxide to Alts. 21-24 0% 0%
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Cost Comparison of Top 10 AWT Trains Assuming 16-mgd Expansion
Alt. Treatment Train Capacity (mgd)
Cap. Cost
($ mil)
O&M Cost
($ mil/yr)
Cost Ratio
1 Fe Clarification & GMF 27.4 20.5 1.6 1.00
3 Fe Clarification w/PAC & GMF 21.8 17.7 2.1 1.37
5 Fe Clar., Ozonation & GMF 25 28.4 1.9 1.40
7 Fe Clarification & MF 27.4 42.4 2.6 1.84
11 Fe Clar., GMF & GAC 19.7 28.7 2.6 2.08
9 Fe Clar. w/PAC & MF 21.8 35.1 2.9 2.21
2 Lime Clar., Recarb. & GMF 24.2 29.4 4.6 2.43
13 Fe Clar. w/PAC, GMF & GAC 18.2 27.7 3.1 2.44
15 Fe Clar., Ozonation, GMF & GAC
19.1 35.2 2.8 2.47
4 Lime Clar. w/PAC, Recarb. & GMF
21.8 27.9 5.0 2.80
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Some Processes are Better at Removing Microconstituents
TOC removal is not a perfect surrogate for microconstituents removalBest processes for removing microconstituents are:— Reverse Osmosis (Alternatives 21-24)— Biologically Active Filtration (BAC), i.e., ozonation
preceding GMF (Alternative 5)— Nanofiltration
Chemical Clarification followed by shallow bed filtration is not very effective at removing Endocrine Disrupting Compounds (EDCs) and Pharmaceuticals & Personal Care Products (PPCPs)
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
AWT Train Suggested for Future Consideration: Chemical Clarification, Ozonation, and Deep Bed Filtration (Alt 5)
O3AIR
Ferric Chloride
Polymer
Wilson Creek RWWTP
Secondary Effluent
Clarification Deep Bed Filtration
ClearwellGravity Thickening
Filter Backwash Equalization/Clarification
Mechanical Dewatering
To Wilson Creek
Dewatered Residual to Land Disposal
Residual Centrate/Filtrate to Sewer
Ozonation
UV Disinfection
Filtration
81.3% TOC Removal 88.5% TP Removal
Approximately 40% more costly, but provides removal of EDCs and PPCPs
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Chemical Clarification Downstream of Existing Secondaries (Alt. 1) Recommended Based on Cost Evaluation
Ferric Chloride
Wilson Creek RWWTP
Secondary Effluent
Clarification
Gravity Thickening
Dewatered Residual to Land Disposal
Residual Centrate/Filtrate to Sewer
Polymer
To Wilson Creek RWWTP Filters
58.5% TOC Removal 88.5% TP Removal
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Agenda
Voyage OverviewTreatment ApproachModel ScenariosInput DataScenario ResultsComments and Questions
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Scenario 1Cap TOC Mass Loading at Wilson Creek—Use TOC as an indicator for organic contaminants
of emerging concern—Add advanced water treatment (AWT) processes to
maintain effluent TOC load equivalent to 48-mgd secondary treatment level
No Limit on Phosphorus
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Scenario 2Cap TOC Mass Loading at Wilson Creek—TOC limits per Scenario 1
Limit Phosphorus Load to Lake Lavon—Reservoir Phosphorus target equal to P allowed by
current permit• 64 mgd at 0.5mg/l, 267 lbs/day
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Scenario 3Cap TOC Mass Loading at Wilson Creek—TOC limits per Scenarios 1 & 2
Limit Phosphorus Load to Lake Lavon—More stringent P target—Maintain current mass loading of P to reservoir
• 48 mgd at 0.5 mg/L, 200 lbs/day—Includes estimated P load from wetlands treated
water • 2030 flow of 49.4 mgd at 0.3 mg/L, 123.6 lbs/day
—Allowable WWTP P load• 200 lbs/d – 123.6 lbs/d = 76.4 lbs/d
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Scenarios 4 & 5Potential future system alternativesScenario 4—Scalping Plant vs Transmission from
Wilson Creek RWWTP to meet reclaimed water demands
Scenario 5—Impact of 5 potential future customers
connected to system
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Agenda
Voyage OverviewTreatment ApproachModel ScenariosInput DataScenario ResultsComments and Questions
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Input Data
Estimated Capital Costs—Including engineering, legal, and admin—Pipelines, including construction, ROW,
easements—Pump Stations—Existing WWTP Conventional Expansion —Existing WWTP Advanced Treatment—New RWWTP Construction, including
future expansions
Estimated O&M Costs for each facility
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Input Data
H2O Map Sewer Data—Flows—Capacities (dia, slope, invert elevations)
New WWTP Locations (4 provided by NTMWD)Other Phosphorus Loads to ReservoirReclaimed Water DemandPotential Future Customers
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Major Infrastructure Components
Collection & Transmission—Gravity Sewers—Force Mains—Pump Stations
Treatment—Conventional,
expansion in kind—Advanced
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NTMWD Wilson Creek System Diagram & Demonstration
Future Customers (Scenario 5)
New Force Mains
Existing Force Mains
New Treatment
Existing WWTP
Scalping (Scenario 4)
Existing Interceptors
New Interceptors
Effluent Transfer
Effluent Water Quality
Advanced Treatment
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Agenda
Voyage OverviewTreatment ApproachModel ScenariosInput DataScenario ResultsComments and Questions
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
Scenario Results: Capacity Expansions by 2030
0102030405060708090
100
Baseline 1: No P Target 2: P Target 1 3: P Target 2
Scenario
Cap
acity
(mgd
)
Existing WWTP AWT at Existing WWTP Effluent Transfer New WWTP
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Scenario Results: Life Cycle Costs
$570M
$464M
$523M
$621M
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Scenario Results: Capital Costs$293M
$257M$267M $266M
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Scenario Results: O&M Costs
$277M
$207M
$256M
$355M
Copyright 2009 by CH2M HILL, Inc. • Company Confidential
ObservationsExpanded capacity at Wilson Creek RWWTP less expensive than a new WWTP—Economy of scale
• consolidation of capacity at one location is more cost effective for both capital and operating costs
—Transmission costs• cost of new transmission to proposed WWTP offsets
possible savings arising from capacity relief in existing interceptors
Advanced Treatment and Effluent Transfer can meet effluent water quality load targets—Advanced treatment is preferred for more stringent
Phosphorus targets—Effluent transfer is favorable for less stringent
Phosphorus targets