Indirect Potable Reuse (IPR): Reno-Stead WRF Pilot Test Results

NDEP Workshop

August 10th 2011

ac-ft

/ ye

ar

Stead, Lemmon Valley & Cold Springs Area

Greater Reno Area Forecast of Long-Term Water Needs

Source: The City of Reno and Washoe County TMSA/FSA Water, Wastewater and Flood Management Facility Plan, 2007.

Indirect Potable Reuse (IPR)• Augment potable water supplies using recycled water• Recycled water injected into groundwater aquifer and held

for a defined period of time prior to being pumped for potable use

• Concerns include: – Pathogens– Chemical toxicity (e.g., Carcinogenicity)– Total Dissolved Solids (TDS)– Contaminant leaching from the aquifer – Well clogging

• Benefits include:– Elimination of dual-pipe infrastructure; cost diverted to treatment

rather than piping– Reduced maintenance and enforcement concerns

IPR - State of the Industry

• California• Washington• Arizona• New Mexico• Florida• Massachusetts• Texas*• Hawaii** No Statewide IPR/ASR Standards Exist. Projects are permitted on a

case-by-case basis.

CaliforniaDraft Recharge Regulations (Aug 2008)• Residence time ≥ 6 months • Essentially pathogen free• TDS ≤ 500 mg/L• TOC ≤ 0.5 mg/L (100% Effluent)• 250+ Contaminants with regulatory limits

– Drinking Water MCLs– California Toxics Rule (CTR) List

• Contaminants of Emerging Concern (CECs)– 1.2 log N-Nitrosodimethylamine (NDMA) reduction– 0.5 log 1,4-Dioxane reduction– Monitoring of pharmaceuticals and endocrine disruptors

California – Status of CEC Monitoring

• Blue Ribbon Panel Report Recommendations (Jun 2010)– Based on toxicological relevance: NDMA, 17β-estradiol, caffeine &

triclosan– Viable performance indicators: DEET, gemfibrozil, iopromide, and

sucralose– Surrogates: Ammonia, DOC and Conductivity

• CDPH Staff Report Recommendations (Nov 2010)– Blue Ribbon Panel recommended constituents– CECs: bisphenyl A, boron, carbamazepine, chlorate, Cr-VI, diazinon,

1,4-dioxane, naphthalene, NDEA, NDPA, n-nitrosodiphenylamine, NPYR, 1,2,3-TCP, TCEP, and vanadium.

– Surrogates: Nitrate, UVA absorption, turbidity, chloride residual, and total coliform.

Blue Ribbon Panel and CDPH Staff Reports

• All aquifers are classified for drinking water protected use unless specifically reclassified

• Aquifers that are classified for drinking water protected use:– Selected Drinking Water MCLs– Pesticides and polychlorinated biphenyls (PCBs)– Pathogens– Turbidity

• Aquifers that are reclassified to a non-drinking water protected use:– Submit petition for reclassification– Contaminants that are specifically identified in the petition

ArizonaNumeric Water Quality Standards (Dec 2008)

WashingtonWater Reuse Standards (Sep 1997)• Indirect Potable Reuse

– BOD, TSS and Pathogens– Residence Time and Horizontal Separation Distance– Drinking Water MCLs– Total Nitrogen (TN) ≤ 10 mg/L– TOC ≤ 1 mg/L

Updates• Revisions are expected by June 2013

New Mexico• No regulations at present• Rio Rancho Advanced Water Treatment Pilot & Aquifer

Recharge Demonstrations– Treatment train consisted of MBR-O3/H2O2-BAC– Potable water was used in groundwater recharge pilot testing

• Limitations under development– Expected treated water quality objectives are:

• TOC ≤ 3 mg/L• TDS ≤ 1000 mg/L

• Planning for a 0.5 MGD Demonstration Project

Texas

• IPR projects are permitted on a case-by-case basis.• El Paso Recharge Project (Since 1985)

– Effluent limitations were based on Water Factory 21 project– Treatment train consist of powdered activated carbon, ozone, and

biologically active carbon filtration (BAC) processes– Recharge wells require minimum backwash and maintenance

FloridaRecharge Regulations (1999)• Groundwater TDS > 3000 mg/L

– Horizontal Separation Distance– Drinking Water Maximum Contaminant Levels (MCLs)– Pathogens– Total Nitrogen (TN) ≤ 10 mg/L

• Groundwater TDS ≤ 3000 mg/L– Horizontal Separation Distance– Groundwater TDS > 3000 mg/L Constituents– Total Organic Carbon (TOC) ≤ 3 mg/L– Total Organic Halogens (TOX) ≤ 0.2 mg/L– Field Trials

MassachusettsMADEP 314 CMR 5.00 (March 2009)For discharges to a groundwater within a wellhead protection area:•Discharges outside the two-year time of travel to the well

– TSS ≤ 10 mg/L– Turbidity ≤ 5 NTU– TOC ≤ 3 mg/L

•Discharges within a two-year time of travel to the well– TSS ≤ 5 mg/L– Turbidity ≤ 2 NTU– BOD ≤ 10– TOC ≤ 1 mg/L– Total Nitrogen ≤ 5 mg/L– Nitrate as N ≤ 5 mg/L

Treatment Options for IPR

• Reverse Osmosis with Advanced Oxidation (RO-UV/H2O2)– Orange County and nearby cities, CA– Scottsdale, AZ (RO only, no UV/H2O2)

• Ozone-Biologically Active Carbon Filtration (O3-BAC)– El Paso, TX (ozone only; no peroxide)– Reno, NV (pilot test)– Rio Rancho, NM (pilot test)

• Soil-Aquifer Treatment (SAT)– Various locations, AZ– During land disposal of wastewater effluent, Nationally

Category RO-UV-Peroxide Ozone-BAC

CECs (EDCs and PPCPs) Concentrated in brine stream

Degraded and/or adsorbed

Reject/Side Streams Some None

Total Dissolved Solids (TDS) Concentrated in brine stream Unchanged

Corrosivity Increased Unchanged

Net TOC Removal Limit of Technology ≤0.5 mg/L

Function of carbon change out frequency.

Energy, Maintenance, & Capital Cost

Highest on all accounts Substantial Advantage

Comparison of Treatment Trains

OzoneOzone--BAC treatment train was selected for pilot testing. BAC treatment train was selected for pilot testing.

Reno-Stead Pilot Testing Project Overview• Develop an advanced treatment process train for IPR

applications applicable to inland areas (without ocean discharge)

• Demonstrate that it can reliably produce effluent suitable for aquifer storage with greater ionic and biological stability than occurs with reverse osmosis based treatment

• Demonstrate that it can eliminate chemical based toxicity and reduce byproducts

• Investigate Ozone and BAC design elements:– Ozone dosage optimization– Ozone byproduct mitigation– Disinfection effectiveness– BAC startup and monitoring

Reno-Stead Pilot Testing• Reno-Stead WRF (RSWRF)

– Average Flowrate = 1.5 Mgal/d– Mean Cell Residence Time (MCRT) = 17 to 25 days

• MF-O3-BAC Pilot System – Sep 2008 to Dec 2009– Flowrate = 10.7 gpm

Effluent Returned To RSWRF Headworks

• 3 Main sampling events• Clean sampling techniques• 490 Contaminants• Sampling included field blanks and duplicates• Sampling and quantification of contaminants

after each treatment process• First main sampling event was redone due to

out-of-range sample temperature

Pilot Testing Sampling Program

Membrane System

WesTech Membrane Unit

• 17 - 25 gpm• 0.01 mm pore size• 35 psi Operating

Pressure• Clean-in-place (CIP)

agents and intervals were developed during the pilot testing period

• Cleaning Agents Used:– Citric Acid– Caustic– Hypochlorite

Byproducts:•Bromate•Biodegradable dissolved organic carbon (BDOC)•Organics (NDMA, aldehydes)

Ozonation & Its Byproducts

APTwater Ozone Unit

Phenol

Short-Chain Acids and Aldehydes

0

20

40

60

80

100

DEET Fluoxetine Phenytoin Sulfamethoxazole Meprobamate Estrogenic Activity(as EEq)

Constituent

Det

ecta

ble

Con

stitu

ent R

emov

al (%

)

3 mg/L Ozone Dosage5 mg/L Ozone Dosage7 mg/L Ozone Dosage

Contaminant of Emerging Concern (CEC) Removals as a Function of Ozone Dose

< 5 < 5

1937

1

10

100

1000

10000

Bromate Methyl Glyoxal Ethyl Glyoxal Formaldehyde Acetaldehyde BDOC

Constituent

Con

cent

ratio

n ( μ

g/L)

Ozone Influent (avg.) 3 mg/L Ozone Dosage5 mg/L Ozone Dosage 7 mg/L Ozone Dosage

Ozonation Byproducts

Effect of Peroxide on Bromate Formation

• Activated carbon colonized by microbes

• Backwashed regularly (10-14 days)– Biomass control– Removal of suspended solids

• Takes 3 to 6 months to develop without seeding

Biologically Active Carbon (BAC) Filtration

WesTech BAC Unit

• Main component of membrane (or skin) of microbes

• Phospholipids breakdown rapidly upon cell death

• Biomass calculated based on PLFA does not contain dead cells

• Provides info onmicrobial communitystructure

Phospholipids Fatty Acids (PLFA)

Source: Microbial Insights Inc.

Increase in BAC Biomass Over Time

0

20

40

60

80

100%

Tot

al P

LFA

4 16 30 44 58 72 169 262 288 ElPasoBAC

Days Since Startup

Proteobacteria GeneralEukaryotes Anaerobic metal reducers Firmicutes Sulfate Reducing Bacteria

Reno BAC

Increase in BAC Microbial Diversity Over Time: Bed Depth = 0.5 ft

Ozone-BAC Effluent Water Quality

0

10

20

30

40

Estr

adio

l Equ

ival

ents

EE

q (n

g/L)

SecondaryEffluent

MFEffluent

O3 Effluent BACEffluent

Field blankE-Screen

Yeast - YES

Bioassay ResultsEstrogenic Activity using E-Screen & Yeast Estrogen Screen (YES)

• Average 1,4-Dioxane removal during ozonation = 77%• California Draft Recharge Regulations requires at least 0.5-log

1,4-Dioxane reduction (± 68.4% removal)

1,4-Dioxane

N-Nitrosodimethylamine (NDMA)

0

4

8

12C

once

ntra

tion

( μg/

L)

Secondary

Effluent

MF Effluen

t

O3 Efflu

ent

BAC Effluen

t

Field Blan

k

18-Aug-0917-Nov-0909-Dec-0915-Dec-09

NM NMNM

NM = Not Measured

• Average effluent NDMA concentration = ≤ 0.28 ng/L (Non-Detect)• NDMA California notification level = 10 ng/L• NDMA National Toxics Rule (NTR) Limit = 0.69 ng/L

0

5

10

15

20

25

30

Mar Mar Apr Apr May May Jun Jun Jul Aug Nov Dec

2009 Date

Bro

mat

e ( μ

g/L)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

Am

mon

ia (m

gN/L

)

O3 Effluent BromateO3 Influent Ammonia

Bromate Mitigation with Peroxide and Seasonal Ammonia Addition

• Average effluent bromate concentration after mitigation = 3.8 μg/L• Bromate MCL = 10 μg/L

Ammonia maintained at ±1 mg/L

0

40

80

120

160

Con

cent

ratio

n ( μ

g/L)

Mar-09Mar-09

Apr-09Apr-09

May-09Aug-09

Nov-09Dec-09

Acetaldehyde Formaldehyde Ethyl Glyoxal Methyl Glyoxal

Removal of Ozone Byproducts by BAC

Acetaldehyde

Formaldehyde

Ethyl Glyoxal

Methyl Glyoxal

0

2

4

6

8

10

12

14

Feb-09 Apr-09 Jun-09 Jul-09 Sep-09 Nov-09 Dec-09Date

Tota

l Org

anic

Car

bon

(mg/

L)Secondary Effluent MF EffluentO3 Effluent BAC Effluent

TOC

Biodegradable Dissolved Organic Carbon (BDOC)

COD

UV Transmittance at 254 nm (UVT254)

Constituents Not Detected / Inconsistent Results

• Dioxins• Volatile Organic Compoundsa (VOCsa)• Synthetic Organic Chemicals (SOCs)• Pesticides, Herbicides & Polychlorinated Biphenyls (PCBs)• Haloacetic acidsb (HAA5b)• Alcohols and Glycols• Diquat, Endothall and Fumigants

a Acetone formed during ozonation and removed during BAC treatmentb Monochloro acetic acid formed during ozonation and removed during

BAC treatment

Sample Location MS2 (pfu/100 ml)

Fecal Coliform(MPN/100 ml)

Total Coliform(MPN/100 ml)

Secondary Effluent Not Measured >2400 2400

Membrane Effluent 1.1 X 108 <0.9 <0.9

After Ozonation3.5 mg/L H2O2 & 5 mg/L O3

1- 6 <0.9 <0.9

After BAC Not Measured <0.9 <0.9

MS2 and Coliform Inactivation• Pathogen inactivation standards are based on poliovirus and/or

coliforms• Poliovirus requires special license/approval for use• MS2 Coliphage (Male Specific Phage Bacteria)

– A good indicator of chlorine and UV disinfection– A cost effective, non-infectious surrogate to poliovirus

• With regards to ozone disinfection, previous studies showed that 6.5 log-removal of MS2 is equivalent to 5 log-removal of poliovirus

Pathogens - Coliforms

0

5

10

15

20

25

30

0 50 100 150 200 250 300

Days Since Startup

Bac

kwas

h In

terv

al (D

ays)

1

10

100

1000

10000

BA

C E

fflue

nt T

otal

Col

iform

s (M

PN/1

00 m

l)

Backwash Interval

Total Coliform

Effect of Virus Seed TOC on MS2 Disinfection

• TDS• CEC Removal• Bulk Organics • Sustainability (in terms of energy/chemical use and

brine handling)• Energy Consumption

Process Train Comparison

Orange County, CA• Chloramination• Microfiltration (MF)• Sulfuric Acid and Inhibitor Addition• Reverse Osmosis (RO)• High-Energy UV-Hydrogen Peroxide

(Peroxide)• Excess CO2 Stripping• Lime Stabilization

RO-UV/H2O2, GWRS, Orange County

MF-Ozone-BAC MF-RO-UV-Peroxide

Does not remove TDSEffluent corrosivity is unchanged

Removes TDS (Ca2+)Increases the corrosivity of treated effluentHigher probability of leaching of subsurface soil constituents (Arsenic)

RSWRF Influent TDS = 395 ± 50 mg/L (current)Orange County Sec. Effluent TDS = 935 mg/L (average)

Process Train Comparison: TDS

-10

-8

-6

-4

-2

0

MF-O3-BAC RO

LSI

InfluentEffluent

NO DATA

Langelier Saturation Index (LSI)

Target LSI

0

200

400

600

800

1000

1200

MF-O3-BAC RO

TDS

(mg/

L)

InfluentEffluent

National Secondary DW MCL

TDS

MF-O3-BAC (Reno) Vs. RO (Orange County): TDS & LSI

MF-Ozone-BAC MF-RO-UV-PeroxideEffective in removing CECs RO concentrates the CECs -

Advanced oxidation step might be required

Removal of CECs

MF-O3-BAC Vs. RO: Water Quality Comparison

MF-Ozone-BAC MF-RO-UV-PeroxideRemoves THM PrecursorsRemoves odor causing CompoundsRemoves oxidation byproducts that are responsible for well clogging

Limit of technology ≤ 0.5 mg/L effluent TOCTHM precursors, odor causing compounds, and oxidation byproducts are assumed to be low when TOC ≤ 0.5 mg/L

Bulk Organics

0

4

8

12

MF-O3-BAC ROTO

C (m

g/L)

Influent

Effluent

• Various approaches to TOC in recharge regulations:─ CA: TOC ≤ 0.5 mg/L

(100% Treated Effluent)─ WA: TOC ≤ 1 mg/L ─ FL: TOC ≤ 3 mg/L ─ MA: TOC ≤ 1-3 mg/L

• Significance of residual MF-O3-BAC TOC not yet known

MF-O3-BAC Vs. RO: TOC

MF-Ozone-BAC MF-RO-UV-PeroxideBAC utilizes bioregenerationOzone generation costLow-pressure (LP) MF pumping costLow-energy UV lampsConsumes less energyNo loss of water resourceNo brine waste requiring further treatment and/or disposal

More intensive maintenanceLP-MF and RO pumping costHigh-energy UV lamps (requires 7-8 times more UV energy than disinfection)

Highly energy intensive (consumes 3-4 times more energy than MF-Ozone-BAC-UV)

10-20% Loss of water resourceRequires RO concentrate disposal

Sustainability and Energy Consumption

Project Findings• The MF-O3-BAC pilot project has successfully

demonstrated multi-barrier process capabilities to:– Reduce wide range CEC to very low and non-detect

concentrations– Provide effective disinfection by inactivating virus and coliforms– Stable and less corrosive final effluent with no residual toxicity– Significantly reduce BDOC concentrations to minimize

biofouling in injection wells– Remove ozonation transformation byproducts such as bromate

and NDMA– Provide sustainable treatment in terms of energy and chemical

use

These removals are achieved at lower costs and power utilizationThese removals are achieved at lower costs and power utilizationthan RO, and without generating a reject brine stream needing than RO, and without generating a reject brine stream needing special treatment and/or disposalspecial treatment and/or disposal

Next Steps• Evaluate TOC impacts on receiving aquifer water

quality• Further optimize design parameters

– BAC treatment possibly include mechanisms such as biodegradation and adsorption.

– Can these removal mechanisms be leveraged individually in two steps: a biofilter and a GAC adsorption unit?

• Further optimize operation and monitoring– Reducing CEC monitoring to selected indicators based on

toxicological relevance and performance evaluation

• Monitor changes in final effluent quality during aquifer storage

Demonstration of Advanced Treatment followed by Groundwater Injection • Advanced treatment of secondary effluent

– Designed to address CECs, pathogens, particulates & biodegradable DOC

• Evaluation of groundwater injection– Monitor water quality during injection, storage and recovery– Evaluate potential for degradation of stored water quality via

dissolution of natural contaminants in the aquifer– Evaluate effluent deoxygenation requirements– Perform hydrogeologic investigation and submit an application for

injection permit– Monitor hydrogeological and water quality parameters

Acknowledgements• Reno-Stead WRF Plant Staff• TMWRF Lab Staff• University of Nevada, Reno • Southern Nevada Water Authority• City of Auburn• WesTech• APTWater• Calgon Carbon• Microbial Insights• Weck Laboratories• Wisconsin State Lab• BioVir Laboratories

Questions & CommentsPlease contact:Michael A. Drinkwater, P.E.Associate Civil Engineer – SanitaryCity of RenoP.O. Box 1900Reno, NV 89505Phone: (775) 334-3393Email: DrinkwaterM@reno.gov

We would appreciate all comments by Friday, August 26th.

This presentation may be downloaded from http://www.reno.gov/index.aspx?page=649