Direct Potable Reuse

Drivers, Regs, and Economics

John Rehring, P.E.

RMWEA/RMSAWWA JTAC Luncheon

Denver, CO | March 19, 2015

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Potable Reuse

DPR

Indirect Potable Reuse

Environmental Buffer

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Drivers for DPR

Regulatory Approaches

DPR Economics

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DPR is Getting “Closer to Home”

Cloudcroft

Big Spring Brownwood

Wichita Falls

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The U.S. Drought Monitor is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Map courtesy of NDMC-UNL.

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Texas Reservoir Levels as of March 2015

WaterDataForTexas.org

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Water Sustainability Risk Index due to climate change in 2050 (Roy et al., 2012)

Climate models: By 2050…• Southwest will become more hot, more dry

• Snowpack dynamics and “storage” will change

• Extended droughts with intense precipitation events and variability

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• “Goals and Measurable Outcomes”– “…reaching enhanced levels of

municipal conservation and reuse.”– “…continue to make the most efficient

use of their supplies.”– “…water reuse and conservation is a

critical component of meeting future water needs.”

“…conservation and reuse will help address Colorado’s growing

demands while upholding our Water Values.”

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Perspectives are Quickly Evolving on Augmenting Potable Supplies with Purified Water

“…could significantly increase the nation’s total available

water resources.”National Research Council – 2012

“…a solution of last resort…”National Research Council – 1998

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CA Medical Association

supports potable reuse

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Why is POTABLE Reuse Attractive Here?

Landscape Irrigation

Other nonpotable uses

IPR – Surface water augmentation

IPR – Groundwater augmentation

Direct potable reuse

Seasonal

Year-round

Year-round• Drought-resistant• Local• Lower energy• Uses existing infrastructure• Cost-effective

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DPR Initiative: Focused research

• CA legislative mandate to investigate DPR criteria by 2016

• > $6M pledged in support of DPR research

• $4.5M on 26 projects to date

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Drivers for DPR

Regulatory Approaches

DPR Economics

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What are our primary risks with DPR?

Acute • Pathogens

Chronic • Trace Organic Compounds

…plus all the MCLs (of course!)

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Potable Reuse: A Whole New Set of Challenges

Trace Organic Compounds

Pathogens

Monitoring & Treatment

Technologies

Reliability & Redundancy NWRI-NSF Direct Potable Reuse

Treatment Workshop (July 2014):

The CWA and SDWA were not intended to be used for DPR.

CWA + SDWA = IPR

CWA + SDWA = DPR

Non-Potable Reuse: Mitigate Risk by Avoiding Ingestion

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How do we address the “gap”?

Clean Water Act

Safe Drinking Water Act

DPR Regs

How do we transform raw wastewater into a suitable “raw water” for potable supply?

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Case Study: Trace Organic Concentrations vs. Human Health BenchmarksCompound WRF Effluent After O3/BAF At 30% blend

1,7‐Dimethylxanthine

4‐tert‐Octylphenol

Acesulfame‐K Food additive. Human health benchmark not defined.

Amoxicillin

Atenolol

Atrazine

Butalbital Human health benchmark unknown.

Caffeine

Carbamazepine

Carisoprodol Human health benchmark unknown.

Cotinine… and so on …

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Existing Regulations Define Safe Drinking Water for “Regulated” Compounds and Pathogens…Severely impaired High quality

sewageWWTPeffluent

Defined:10-4 risk

drinking water

site-specificquality

site-specificquality

?-raw water-?

…but not how to “get there.”

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Regulatory Approaches to DPR

Severely impaired High quality

sewageWWTPeffluent

Defined:10-4 risk

drinking water

TCEQ Approach (8V/6G/5.5C)

California / WRRF Approach (12V/10G/10C)

site-specificquality

site-specificquality

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Monitoring technology limits options

“Magic Meter”

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Failure response time becomes critical with potable reuse

Sampling Interval

Sample TAT

SystemReaction

time

Identify Failure

Failure Response Time

Respond

Repeat for each combination of:(1) process, (2) pathogen, and (3) monitoring method

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IPR vs. DPR: Natural vs. engineered buffers

Long RRTspossible(months)

Shorter RRTsrequired

(hours – days)

Response Retention Time (RRT)Treatment / Attenuation

Perception

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How do we Compensate for Reduced RRT?

Long RRTspossible(months)

Shorter RRTsrequired

(hours – days)

Accurate monitoring to detect failureAdditional (redundant) treatment

Sufficient storage to test WQ ahead of potable use

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The Range of Potential RRTs is HUGE

Response Retention Time (= Storage Volume)

Monitoring Complexity “Monitoring Focused”

– RRT < 1 hour– Online sensors

for monitoring “Storage Focused” – RRT in months– Conventional

monitoring

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For an Engineered Storage Buffer… Bigger is Not Always Better!

More response time

Reduced monitoring

Stored water quality

Water lost in process upset

MORE is better!

LESS is better!

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DPR Failure Mitigation Alternatives

Diversion of off-spec water

• Monitoring & failure response is critical

“Stand-by” process redundancy

• Monitoring & failure response is critical

“Duty” process redundancy

• Monitoring & failure response is still important but less central

eliabilityR

edundancyR

obustnessR

esilienceR

The Four Rs of Potable Reuse Pecson, Trussell, Pisarenko, and Trussell – JAWWA March 2015

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Monitoring study at Big Spring is assessing new monitoring tools with potential regulatory benefits

Microfiltration UVSecondary

Effluent

H2O2

<20% blend

To drinking water plants

Moss Creek Lake

E.V. Spence Pipeline

RO concentrate

Reverse Osmosis

Raw Water Production Facility

Particle Counts for MF Integrity

Trasar® for RO Integrity Chloramines

for UV dose

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Evolving approach provides more credit for advanced monitoring

MF RO UV/H2O2 Cl2

Process Monitoring Method

Credits Awarded FailureResponse

TimeV P B

MF Pressure decay -- 4 3 24+ hours

RO EC 2 2 2 minutes

UV/H2O2 sensors 6 6 6 minutes

Cl2 Online residual 6 0 6 minutes

Totals 14 12 17 24+ hours

Goals 12 10 9

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MF RO UV/H2O2 Cl2

Process Monitoring Method

Credits Awarded FailureResponse

TimeV P B

MF Pressure decay -- 4 3 24+ hours

RO EC 2 2 2 minutes

UV/H2O2 UV sensors 6 6 6 minutes

Cl2 Online residual 6 0 6 minutes

Totals 14 8 14 minutes

Goals 12 10 9

Evolving approach provides more credit for advanced monitoring

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MF RO UV/H2O2 Cl2

Process Monitoring Method

Credits Awarded FailureResponse

TimeV P B

MF Pressure decay -- 4 3 24+ hours

RO Trasar® 4 4 4 minutes

UV/H2O2 UV sensors 6 6 6 minutes

Cl2 Online residual 6 0 6 minutes

Totals 16 10 17 minutes

Goals 12 10 9

Evolving approach provides more credit for advanced monitoring

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DPR Projects are Informing the Regulatory Process

CRMWD new “Raw Water” has:• Minimal trace pollutants• No detected virus or

protozoa• Very low DBPFP

after RO

Cloudcroft process-intensive approach• Above and beyond the

log removal targets• Strong reliability and

redundancy• Operationally complex

and challenging

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Regulation of DPR in Texas

• “Public Drinking Water”Innovative/alternate treatment clause:“Any treatment process that does not have specific design requirements in 290.42(a) – (f) of this title.”

• Case-by-case approval– Treatment requirements based on

pathogen log reduction credits– Pilot or “full scale verification” required

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California’s IPR Regs: Groundwater Replenishment

• Filtered, disinfected tertiary water

• 12/10/10 log reduction for enteric virus, Giardia, and Crypto

• Total N <10 mg/L• Others < MCL or AL

≥ 5:1 Groundwater:

Recycled Water

Surface water augmentation ≈ GW injection

• RO for injection systems• Virus credit for every 1

month in aquifer storage

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Path Toward National Guidelines

• No National Guidelines or Regulations Exist• Many States and Considering Their Own Approaches

(TX, CA, OK, NM)• Substantial database of information available for

common benefit.

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Path Toward National Guidelines

• Document issues important for developing DPR guidelines

• Overview of topics important in DPR implementation

Purpose

• Public health protection• Multiple barriers• Treatment technologies• WQ & performance

monitoring• Operation management

Focus

• Utility and agency staff• Regulators• Water professionals

interested in DPR

Audience

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Anticipated Outcomes

A resource on DPR including information and expert judgment• Source of information on the protection of public health for DPR• Review the factors and topics related to implementing DPR

Address the need the for potable reuse guidelines• Provide direction and criteria to ensure DPR quality and safety

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Drivers for DPR

Regulatory Approaches

DPR Economics

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NPR vs IPR/DPR:Which set of pipes carries more water?

36”

3 @ 16”3 @ 12”3 @ 6” 1 @ 36”

~$1.5Mto move 25 mgd one mile

~$4.3Mto move 25 mgd one mile

plus existing potable infrastructure

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IPR vs. DPR:

Sometimes IPR = WTW*

* Well-traveled water

WRF

WTP

WTPIPR

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0 * Well-traveled water

WRF

WTP

2 miles

• Drought-resistant• Local• Lower energy• Uses existing infrastructure• Cost-effective

IPR vs. DPR:

Sometimes IPR = WTW*

DPR

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What are our options for cost-effective treatment to meet these goals?

a.k.a… can we achieve the desired removals

without reverse osmosis?

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Define “Performance Parameters”

Parameter Removal Goal

MicrobialVirus (MS-2 bacteriophage) > 12-logProtozoa (Cryptosporidium) > 10-logBacteria (Total Coliform) > 9-log

ChemicalTrace Organic Compounds < 1 ug/L

Estradiol Equivalency (EEQ) < 5 ng/L

N-nitrosodimethylamine NDMA) < 10 ng/L

Step 1

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Define Preferred Combinations

Envi

ronm

enta

l Buf

fers

(opt

iona

l)

Step 2

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Work Through the Excel Interface for Results

DRAFTCA-style FAT for IPR

Step 3

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Key Takeaways: What the Future Holds

Progress will be a function of…Provider Interest

Scarcity / Options

Technology & Costs

Public Acceptance

• Potable reuse is a game-changer for our industry

• Regs are being driven by projects and “demand”

• DPR drives a need for new monitoring technologies and a focus on response times

• Applied research is paving the way for understanding treatment options, treatment goals, and operational guidance