The National Trend towards Direct Potable Reuse

RMWEA/RMSAWWA JTACMarch 19, 2015

Larry Schimmoller/CH2M Hill – Global Technology Leader for Water Reuse

John Rehring/Carollo – Vice President

Agenda

• Introduction• Drivers • Regulatory Approaches• DPR Economics • Water Quality Considerations and Implications to

Treatment• Projects• Public Outreach• Conclusions

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Water Reuse is the Recycling of Treated Effluent for Beneficial Use

Wastewater Treatment Plant

Water Reclamation

Plant

Agricultural Irrigation

Landscape Irrigation

Industrial Uses

Recreational & Environmental Enhancement

Indirect Potable Reuse: Drinking water source (reservoir, aquifer, etc..)

Direct Potable Reuse: pipe to pipe connection

Non-Potable Reuse

Potable Reuse

Treatment Plant Effluent

3

Common Indirect Potable Reuse Approaches

• De Facto reuseWWTP

River

WTP

WWTP AWTPReservoir

WTP

WWTP

Spreading Basins

AWTP

WWTP AWTP

• Surface water augmentation

• Groundwater recharge via spreading basins

• Groundwater recharge via direct injection

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Direct Potable Reuse

WWTP AWTP WTP

Direct Potable Reuse Approaches

WWTP AWTP

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Potable Reuse• Indirect Potable Reuse

– Recycling of reclaimed water back to the potable water system via an environmental buffer

– Environmental Buffer provides:• Retention time to allow response to upset events• Attenuation of contaminants• Blending and dilution with other waters

• Direct Potable Reuse:– Recycling of reclaimed water directly into the potable water

system – Pipe-to-Pipe Connection upstream or downstream of WTP

• Direct potable reuse can provide equivalentwater quality provided the appropriatemonitoring and response time is provided

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History of Potable Reuse

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Denver Direct Potable Reuse Demonstration Plant – Can wastewater be purified to a level equivalent to Denver’s high quality drinking water?• Building on experience learned from the South Lake Tahoe and UOSA

projects, Denver Water built a 1 mgd potable reuse demonstration plant to test the feasibility of direct potable reuse

• $30 million project: most comprehensive direct potable reuse feasibility study ever conducted in the world.

1980 - 1984 1985 - 1989 1990 – 1991 1992 - 1993Engineering and

constructionFor 5 years, the

demonstration plant is operated in alternative

treatment configurations to select the highest performing

treatment.

For 2 years, the highest performing treatment is

subjected to unprecedented water

quality and health effects testing for comparison to Denver’s drinking water.

The final project reportis prepared and

delivered proving the technical feasibility and public health

safety of direct potable reuse.

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Denver Direct Potable Reuse Demonstration Plant – the selected treatment was subjected to unprecedented health effects testing

• $4 million whole animal health effects testing program:• A 2-year chronic toxicity and carcinogenic study on both rats and mice was conducted • A two-generation reproductive toxicity study was conducted.• Notable absence of any negative health effects associated with consumption of either the

reclaimed water or Denver drinking water.

• Findings unequivocally verified the ability of advanced water treatment processes to reliably remove a broad spectrum of pollutants and produce water that satisfies every currently known measure of drinking water safety.

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Denver Direct Potable Reuse Demonstration Plant – the demonstration plant was a touring show piece to foster public understanding & acceptance

Thousands of people from around the world toured the facility. After learning about water treatment and reuse first hand, acceptance of direct potable reuse generally broke down as follows:

1/3 – YES PLEASE 1/3 – MAYBE 1/3 – NO THANK YOU

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1. We can technically do it safely

2. The lime clarification system is O&M intensive – is there a better way?

3. The “Yuck Factor” is a social barrier

Denver Direct Potable Reuse Demonstration Plant – Big Lessons Learned

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Agenda

• Introduction• Drivers • Regulatory Approaches• DPR Economics • Water Quality Considerations and Implications to

Treatment• Projects• Public Outreach• Conclusions

12

Agenda

• Introduction• Drivers • Regulatory Approaches• DPR Economics • Water Quality Considerations and Implications to

Treatment• Projects• Public Outreach• Conclusions

13

Drinking Water & Public Health Protection Basis: Caveats for Potable Reuse

• Drinking water & public health protection guidance and regulations have evolved largely over the past 50 years and have always been founded on the premise that the water supply was either a “natural” surface water or groundwater source.

• Potable reuse violates this premise– Drinking water and public health principles require modification

to assure public health protection when the source of supply is derived from wastewater.

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Drinking Water & Public Health Protection Basis: Caveats for Potable Reuse

“Clean” Surface Water

(USEPA)

“Dirty” Surface Water

(USEPA)

Ground Water

(USEPA)

Indirect PotableReuse (CDPH)

DirectPotable Reuse

(CDPH?)Virus Log Removal 4 4 4 12 14?Crypto Log Removal

3 5.5 0 10 12?

Giardia Log Removal

3 3 0 10 -

• Higher pathogen concentration in source drives the need for additional treatment

Minimizing or eliminating sources of industrial and commercial wastewater is prudent and discouraging residential customers from using toilets and sinks as receptacles for disposal of uncommon wastes (drugs, cleaners, paints, etc…) is important

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Water Quality – Health• Maximum contaminant levels (MCLs) for drinking water must be met

– Also, consider chemicals on CCL3 (e.g., NDMA)

• Pathogens – multiple barriers required for significant log removal• Inorganics (e.g., ammonia, nitrate)

– Biological nutrient removal to produce low levels of ammonia, nitrate, and phosphorus highly recommended

• Organics – Synthetic organic chemicals (e.g., atrazine); volatile organic chemicals (e.g.,

benzene)– Elevated TOC can form THMs and HAAs in potable distribution system; TOC

less than 2-3 mg/L usually required• Heavy metals and Radionuclides:

– Typically not problematic although data analysis is required• Chemicals of Emerging Concern

– No regulations and no known health effects, but multiple barriers typically provided

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Water Quality - Aesthetics• Total Dissolved Solids (TDS)

– Typically, 200 – 400 mg/L of TDS added to the drinking water through the domestic cycle

– USEPA’s secondary MCL (non-enforceable) is 500 mg/L; higher levels can cause taste complaints

• Total Hardness (calcium and magnesium)– Between 50 – 150 mg/L as CaCO3 is

typically targeted for potable water to avoid customer complaints (taste, spotting on glassware)

0

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3

4

5

6

7

8

9

10

A B C D E F G H ISample

Tast

ers

Scor

es(H

ighe

r is

Bet

ter)

0

100

200

300

400

500

600

700

800

900

1000

TDS

(mg/

L)

TDS Goal: 400 mg/L

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Regulatory Considerations for Direct Potable Reuse• Regulations for Indirect Potable Reuse (IPR) exist in

some states in the U.S. and Australia, but there are no regulations for Direct Potable Reuse (DPR)

• California is currently considering the feasibility of regulating DPR

• DPR regulations under consideration are highly influenced by existing IPR regulations

• Texas has approved one DPR project; one other DPR project (Windhoek, Namibia)

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Regulatory Examples for Potable Reuse Parameter California (IPR) Texas (DPR) USEPA (IPR)

Total Organic Carbon (TOC)

< 0.5 mg/L RO required < 2 mg/L (of WW origin)

Pathogens Virus: 12-log LRVCrypto: 10-log LRVGiardia: 10-log LRV

MF, RO, and UV required

Multiple barriers required (Total Coliform BDL)

Nitrogen TN < 10 mg/L None None

Chemicals of Emerging Concern (CECs)

Reverse Osmosis (RO) and advanced

oxidation treatment req’d

RO required None

Miscellaneous Drinking water MCLs Drinking water MCLs; 80% min

dilution req’d

Drinking water MCLs; Turbidity < 2

NTU

Note: This table summarizes the most significant parameters. Other requirements exist but are not shown for simplicity. IPR = Indirect Potable ReuseDPR = Direct Potable Reuse

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Operational Potable Reuse Plants

Project Location Type of Potable Reuse Year CapacityCurrent Advanced Treatment Process

Montebello Forebay, CA, US Coastal GW recharge via spreading basins 1962 44 mgd GMF + Cl2 + SAT (spreading basins)

Windhoek, Namibia Inland Direct potable reuse 1968 5.5 mgd O3 + Coag + DAF + GMF + O3/H2O2+ BAC + GAC + UF + Cl2 (process as of 2002)

UOSA, Virginia, US Inland Surface water augmentation 1978 54 mgd Lime + GMF + GAC + Cl2Hueco Bolson, El Paso, TX, US Inland GW recharge via direct injection

and spreading basins 1985 10 mgd Lime + GMF + Ozone + GAC + Cl2

Clayton County, GA, US Inland Surface water augmentation 1985 18 mgd Cl2 + UV disinfection + SAT (wetlands)

West Basin, El Segundo, CA, US Coastal GW recharge via direct injection 1993 12.5 mgd MF + RO + UVAOP

Scottsdale, AZ, US Inland GW recharge via direct injection 1999 20 mgd MF + RO + Cl2Gwinnett County, GA, US Inland Surface water augmentation 2000 60 mgd Coag/floc/sed + UF + Ozone + GAC

+ Ozone

NEWater, Singapore Coastal Surface water augmentation 2000 146 mgd (5 plants) MF + RO + UV disinfection

Los Alamitos, CA, US Coastal GW recharge via direct injection 2006 3.0 mgd MF + RO + UV disinfection

Chino GW Recharge, CA, US Inland GW recharge via spreading basins 2007 18 mgd GMF + Cl2 + SAT (spreading basins)

GWRS, Orange County, CA, US Coastal GW recharge via direct injection

and spreading basins 2008 70 mgd (3.1 m3/s)

MF + RO + UVAOP + SAT (spreading basins for a portion of the flow)

Queensland, Australia Coastal Surface water augmentation 2009 66 mgd via three plants MF + RO + UVAOP

Arapahoe County, CO, US Inland GW recharge via spreading 2009 9 mgd SAT (via RBF) + RO + UVAOP

Aurora, CO Inland Surface water augmentation (indirect potable reuse) 2010 50 mgd SAT (via RBF) + Soft + UVAOP +

GMF +GAC

Big Spring ,TX, US Inland Direct potable reuse through raw water blending 2013 1.8 mgd MF + RO + UVAOP

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Direct Potable Reuse Examples –Windhoek, Namibia (1968 – Present)

• GAC-based treatment approach

• Multiple organic barriers: DAF, ozone, BAC, GAC

• Multiple pathogen barriers: filtration, ozone, BAC, UF, Cl2

Lahnsteiner et al, Aqua Services & Eng Ltd, 2007

RESERVOIR WATER

O3O3

PRE-OZONATION

SECONDARY EFFLUENT

FLOCCULATION

AIR

DAF DUAL MEDIA FILTRATION

MAIN OZONATION

BAC 2 STAGE GAC ULTRAFILTRATION CHLORINE CONTACT

FERRIC CHLORIDE NAOH KMNO4

CL2NAOH

POTABLE WATER

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Direct Potable Reuse Examples –Big Spring, Texas

• RO-based plant• Multiple organic

barriers: RO, UVAOP

• Multiple pathogen barriers: MF, RO, UVAOP

• Water treatment plant included downstream for additional pathogen and organics barriers

Marlo Berg, TCEQ, 2011

HYDROGEN PEROXIDE

MEMBRANE FILTRATION

REVERSE OSMOSIS

UV ADVANCED OXIDATION

RAW WATER RESERVOIR

RAPID MIXFLOCCULATORSSEDIMENTATION BASINSFILTERS

THOMAS PIPELINE

SECONDARY EFFLUENT

DISTRIBUTION SYSTEM

POTABLE REUSE PLANT

WATER TREATMENT PLANT

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Key Considerations for DPR Treatment Train Selection

• Equalization of flow required to capture diurnal flows, attenuate water quality, and to provide steady flow to advanced treatment processes

• Multiple barriers to pathogens are required• Multiple barriers to organics are required• Significant storage of finished water is required to allow

water quality monitoring prior to pumping to potable water distribution

• Questions that may further influence DPR treatment selection:– Where in potable water distribution system will water be introduced

(Upstream of WTP? Directly into distribution system?)– What will regulators require?– What will public expect? 23

DPR Treatment Train Examples

MF/UFReverse Osmosis UV AOP

Potable Water

WWTP Secondary Eff

Storage & WQ

MonitoringEqualization Floc/Sed

MF-RO-UVAOP

MF/UF Nanofiltration UV AOP

Potable Water

WWTP Secondary Eff

Storage & WQ

MonitoringEqualization Floc/Sed

MF-NF-UVAOP

Floc/Sed Ozone BAC GAC UV

FLOC/SED-OZONE-BAC-GAC-MF-UV

Potable Water

Storage & WQ

Monitoring

WWTP Secondary Eff

Equalization

Cl2

MF/UF

RO-Based

NF-Based

GAC-Based

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Treatment Train ComparisonContaminant Log Reduction Credits or Barrier (Y/N)

RO-Based NF-Based GAC-Based Enteric Viruses 15-logs 15-logs 14-logsCrypto 14-logs 14-logs 9-logsGiardia 15-logs 15-logs 13-logsSuspended Solids 3 barriers 3 barriers 3 barriersDissolved Metals 2 barriers 2 barriers 1 barriersDissolved Organics 3 barriers + 3 barriers 3 barriers (but concerned

about high THMs and HAAs)

Dissolved Nutrients 2 barriers + 2 barriers 1 barriersSalts 1 barriers + 1 barriers 0 barriers

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Treatment Train ComparisonContaminant Log Reduction Credits or Barrier (Y/N)

RO-Based NF-Based GAC-Based Enteric Viruses 15-logs 15-logs 14-logsCrypto 14-logs 14-logs 9-logsGiardia 15-logs 15-logs 13-logsSuspended Solids 3 barriers 3 barriers 3 barriersDissolved Metals 2 barriers 2 barriers 1 barriersDissolved Organics 3 barriers + 3 barriers 3 barriers (but concerned

about high THMs and HAAs)

Dissolved Nutrients 2 barriers + 2 barriers 1 barriersSalts 1 barriers + 1 barriers 0 barriersWWTP Improvements Required?

No Probably (nitrogen removal)

Yes (nitrogen removal)

Cost Considerations CAPEX is most likely similar between all three treatment trains, except at inland locations where treatment/disposal of RO

concentrate is required

OPEX is most likely the lowest for the GAC-based train and highest for the RO-based train.

$0

$50,000,000

$100,000,000

$150,000,000

$200,000,000

$250,000,000

$300,000,000

$350,000,000

$400,000,000

- 10 20 30 40 50 60 70 80 Plant Capacity (MGD)

Capital Costs

Floc/Sed/O3/BAC/GAC/UV

MF/RO/UVAOP (Ocean Disposal)

MF/RO/UVAOP(mech evap)

MF/RO/UVAOP(evap ponds)

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Water Quality Monitoring at Critical Control Points is Important

RO FEED PUMP

MEMBRANE BIOREACTOR (MBR)

TO POTABLE WATER LINE

ACID, SCALE

INHIBITOR

ROC TO BAUEREI WWTP

CHLORAMINE

SODIUM BISULFITE

WATER QUALITY

MONITORING & STORAGE

STABILIZATION

CALC

IUM

CHL

ORI

DE,

SODI

UM H

YDRO

XIDE

,CA

RBON

DIO

XIDE

2.5 m3/s

HYDROGEN PEROXIDE

DEAERATION TANK

REVERSE OSMOSIS

UVD UVAOP

2.0 m3/s

1.9 m3/s

0.6 m3/s

1.9 m3/sSODIUM

HYPOCHLORITE

TO TIETE RIVER

CCP #1:TURBIDITY (ON-LINE)

TOTAL COLIFORM (DAILY)

CCP #2:TOC (ON-LINE)

CONDUCTIVITY (ON-LINE)

CCP #3:POWER MONITOR

(ON-LINE)

CCP #4:POWER MONITOR (ON-LINE)

H202 DOSE (ON-LINE)

CCP #5:FREE CL2 (ON-LINE)

RO FEED PUMP

MEMBRANE BIOREACTOR (MBR)

TO POTABLE WATER LINE

ACID, SCALE

INHIBITOR

ROC TO BARUERI WWTP

CHLORAMINE

SODIUM BISULFITE

WATER QUALITY

MONITORING & STORAGE

STABILIZATION

CALC

IUM

CHL

ORI

DE,

SODI

UM H

YDRO

XIDE

,CA

RBON

DIO

XIDE

2.5 m3/s

HYDROGEN PEROXIDE

DEAERATION TANK

REVERSE OSMOSIS

UVD UVAOP

2.0 m3/s

1.9 m3/s

0.6 m3/s

1.9 m3/s

SODIUM HYPOCHLORITE

TO TIETE RIVER

Typical Water QualityParameter MBR

TSS, mg/L < 1

BOD, mg/L < 2

Nitrate + Nitrite, mg/L

5

Ammonia, mg/L < 1

TN, mg/L < 10

TP, mg/L < 0.5

Turbidity < 1 NTU

Parameter RO Permeate

pH < 6

Total Hardness (mg/L CaCO3)

< 5

Corrosivity corrosive

TOC, mg/L < 0.5

TDS, mg/L < 20

TN, mg/L < 1

TP, mg/L < 0.05

Parameter FinishedWater

pH 7 - 9

Total Hardness (mg/L CaCO3)

> 50

Corrosivity 0 to -5

TOC, mg/L 0.5 – 1.0

TDS, mg/L 30 - 100

TN, mg/L < 5

TP, mg/L < 0.05

What do Potable Reuse Plants Look Like? Luggage Point AWTP (20 mgd)

Flocculation / Clarification

Raw Water Storage

Membrane & UVAOP Building

Thickener and Centrifuge Bldg

Finished Water Pump Station

Chemical Building

Admin BldgMF/UF

Reverse Osmosis UV AOP

Potable Water

WWTP Secondary Eff

Storage & WQ

MonitoringEqualization Floc/Sed

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Luggage Point AWTPFlocculation / Clarification

Microfiltration

Reverse Osmosis

UV / Advanced Oxidation

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Public Outreach and Education is Important

• Lack of knowledge leaves water management issues vulnerable to political exploitation, to stigmatizing language and misinformation

• Reuse projects are typically rejected due to fear and misunderstanding born from lack of knowledge

• We fail to tell the public about the water that has been recycled around the world for many decades - water reuse is the water industry’s best kept secret

• We focus on the source of the water rather than its quality

• We define “reuse” in a way that scares people

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Recent Research Illustrates that Words and Terminology are very important for Potable Reuse Projects (WRRF-07-03)

The least reassuring terms are the ones the industry uses the most

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Conclusions

• Increasing focus on potable reuse (and DPR) due to drought, population growth, and economics

• Drought-proof water supply• Long history of potable reuse in the U.S. and the world• Only two long-term DPR plants currently in operation but

more to come• Safe water can be reliably produced• Multiple treatment barriers and continual monitoring is

crucial• Public outreach and education is important

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Questions?

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