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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


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?


Agenda

VOYAGE™ OverviewTreatment ApproachModel ScenariosInput DataScenario ResultsComments and Questions


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


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


VOYAGE™ Model Structure

Multilayered approach


VOYAGE™ Data Sources

Existing Information—Master Plans—Existing infrastructure—Operating data

Projections—Population—Usage behavior

Component Model Outputs—Spreadsheets—EPANET—InfoWorks—BioWin


VOYAGE™ Resource System Balances

Water Cycle Components—Demands—Supplies—Treatment—Reuse—Storage—Transmission


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


VOYAGE™ Optimization & Decision SupportEvaluate numerous alternativesOptimize multiple parameters simultaneouslyFind the best combination of decisionsAdvanced optimization algorithmsPowerful communication tool—Customizable graphical

interface—Animation capabilities


VOYAGE™ Water Management Model Typical Example


Agenda

Voyage OverviewTreatment ApproachModel ScenariosInput DataScenario ResultsComments and Questions


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


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


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)


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%


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


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)


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


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


Agenda



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


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


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


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


Agenda



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


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


Major Infrastructure Components

Collection & Transmission—Gravity Sewers—Force Mains—Pump Stations

Treatment—Conventional,

expansion in kind—Advanced


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


Agenda



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


Scenario Results: Life Cycle Costs

$570M

$464M

$523M

$621M


Scenario Results: Capital Costs$293M

$257M$267M $266M


Scenario Results: O&M Costs

$277M

$207M

$256M

$355M


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


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

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