DIRECT POTABLE REUSE

Presented by Mark Farrell, P.E.President- Water Resource Associates

Direct Potable◦ Treating wastewater

to drinking water quality and introducing directly back into the drinking water system

Indirect Potable◦ Treating wastewater

to drinking water quality and dispersing into the environment to be recaptured for additional treatment for drinking water purposes

Potable Reuse

What do you need to do to makedrinking water out of wastewater?

Risk Mitigation

Treatment Public Acceptance

Pathogens & Trace Organic

Compounds

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Types of Indirect Potable Reuse

Saltwater Barrier•Wastewater is treated twice•Groundwater is recovered up-gradient from injection point•Need recovery credits from regulators

Drinking Water

Wastewater treated to

Reclaimed Water Std.

Treat to Drinking Water Std.

Aquifer Recharge/Barrier

Up gradient Aquifer Recovery

Types of Indirect Potable Reuse

ASR & Recovery•Need viable confining unit•Wastewater is treated twice•Arsenic production no longer an issue

Drinking Water

Wastewater treated to

Reclaimed Water Std.

Treat to Drinking Water Std.Aquifer Recharge

Stored Aquifer Recovery

Types of Indirect Potable Reuse

Recharge and Recovery•Groundwater is recovered down-gradient from injection point•Current Arsenic production issue “may” be an issue•Need recovery credits from regulators

Drinking Water

Wastewater treated to

Reclaimed Water Std.

Treat to Drinking Water Std.Aquifer Recharge

Downgradient Aquifer Recovery

Consumer

Wastewater

Treatment

Advanced Water

Treatment

Drinking Water

Treatment

DIRECT POTABLE REUSE (DPR)

Public Acceptance◦ Concerns with health, taste and odor◦ Very technical◦ Media misrepresentations

Safety◦ Human error◦ Contaminant detection methods◦ Buffers

Cost◦ More costly than traditional sources

HURDLES TO DPR

Reclaimed water is owned by utility that produces

Wastewater introduced into the aquifer becomes a State of Florida resource◦ The use of treated wastewater for direct potable

purposes is not regulated by the WMDs because it is a utility property and not a resource of the state

◦ The use of treated wastewater for indirect potable purposes is regulated by the WMD but can be ultimately controlled by the utility

FDEP is preparing new regulations to treat reuse treatment as drinking water

Potable Reuse Regulation

Contaminants of Concern (COC)◦ Any substance that has an adverse effect on

human health that is regulated in drinking water or under consideration at the National level

Constituents of Emerging Concern (CEC)◦ Chemicals of compounds not regulated in drinking

water or reclaimed water and/or not routinely monitored

◦ Constituents that have been present ion the environment for a long time, but for which analytical or health data have only recently become available (NRC, 2012)

Contaminant and Constituent

Category Examples

Disinfection byproducts Chloroform, Trihalomethanes

Household products and food additives

Flame retardents, Sucralose

Industrial Methyl tertobutyl ether

Naturally occurring Hormones (17β-estradiol)

Personal care product ingredients

Fragrances, pigments, Sunscreen

Pesticides Atrazine, Diuron, Lindane

Pharmaceuticals and metabolites

Analgesics, Antibacterials, Antibiotics,Betablockers, Oral contraceptives

Contaminants of Emerging Concern (CEC)

Reliability: A reliable system is redundant, robust and resilient

Redundancy: The use of multiple barriers for the same contaminant, so that risks can be properly managed even in the event of an upset or failure in a unit process.

Robustness: The use of a combination of treatment technologies to address a broad variety of contaminants and changes in concentration in source water.

Resilience: Protocols and strategies to address failures and bring systems back on-line.

THE 4R’S FOR DPR TREATMENT

Treatment Scheme

Flow Capacity Capital Cost ($M/MGD)

O&M Cost ($M/MGD)

Secondary/Tertiary-Ozone-MF/UF-RO-UV/AOP-Stabilization

5 $6.27 $0.78

10 $5.30 $0.70Secondary/Tertiary-MF/UF-RO-UV/AOP-Stabilization-Engineered Storage- WTP

5 $5.38 $0.77

10 $4.66 $0.70

MBR-RO-UV/AOP-Stabilization-Engineered Storage-WTP

5 $5.63 $0.81

10 $4.88 $0.73

Secondary/Tertiary-Ozone-BAC-MF/UF-UV- Chlorine

5 $4.04 $0.40

10 $3.21 $0.35

Secondary/Tertiary-Ozone-BAC-MF/UF- Chlorine- Engineered Storage- WTP

5 $3.81 $0.31

10 $2.98 $0.31

Secondary/Tertiary-Ozone-BAC-UV- Chlorine- Engineered Storage- WTP

5 $2.32 $0.12

10 $1.72 $0.11

TREATMENT COSTS Texas Water Development

Board (2015)

Upper

Florid

an A

quife

r

Seaw

ater

Brac

kish

Gro

undw

ater

Surfa

ce W

ater

Saltw

ater

Intrus

ion

Barrier

Rapi

d In

filtrat

ion

Basin

Crea

ted

Wet

land

Infil

trat

ion

Basin

Indi

rect

Pot

able A

quife

r Rec

harg

e

Aqui

fer S

tora

ge &

Rec

over

y

Direct

Reu

se$0.00

$1.00

$2.00

$3.00

$4.00

$5.00

$6.00

$7.00

$8.00

$9.00

Yield of 10 mgd

Indirect Potable Reuse

Tota

l U

nit

Cost

($/1

,000 g

al)

COMPARATIVE COST OF ALTERNATIVE SOURCES OF WATER SUPPLY

Summary Direct potable reuse is the ultimate recycle for

potable purposes Florida trails the nation in the development of this

water supply source Cost information is still evolving as treatment

trains are being evaluated for the best cost/benefit Recycling wastewater provides the best of both:◦ Sustainable and cost effective water supply◦ Water quality improvement for our coastal water bodies

Public information and safety is the key to development of direct potable reuse