Drinking Water QualityAugust 31 & September 1, 2011

Presented By:

Mark Smith, PE, SJRA GRP AdministratorStan Williams, PE, HDR Project Manager

Agenda

Water Quality – Regulations and Goals Three Steps to Treatment Process

Selection Post Treatment – Quality at the Tap Selected Treatment Processes Next Steps Discussion – Q&A

Perspectives on Drinking Water Quality

Regulators define Drinking Water Quality by:• Numeric Standards• Treatment Techniques• Compliance with Rule & Regulations• Monitoring & Reporting

For Quality Definition – First Look to the Regulations

Evolution of the Safe Drinking Water Act

1986 Safe Drinking Water Act (Update) Cryptosporidium Outbreak in 1993 Resulted

in:• New perspective on surface water treatment• Comprehensive overhaul of industry’s approach • Unprecedented plan for new regulations• Opportunities for innovation in treatment

technology

Drinking Water Quality

Additional contaminants regulated Existing technologies enhanced New treatment technologies developed New Federal Regulations

• ESWTR, D/DBP, D/DBP2, LTESWTR, LT2ESWTR, FBRR, and many more

High Quality Water 20 years ago wouldnot meet today’s standards

Project Quality Standards Consider The Regulations AND the Consumer

Project Standards go beyond the regs• Alkalinity• Hardness• Aggressiveness (corrosiveness)• Odor• Taste

These Constituents AffectWater Quality AT THE TAP

Project Quality Standards Consider The Regulations AND the Consumer

Project Definition of Water Quality:• Compliance with Regulations• Aesthetics at the tap

ClarityTaste & OdorColor

• Healthy and Safe• Compatible with existing groundwater sources• Consistent Quality

Existing Source Waters

Groundwater Characteristics Alkalinity - High Hardness - Moderate Iron & Manganese – Yes Aggressive – Yes

Lake Conroe Characteristics Alkalinity - Low Hardness - Moderate/Low Iron & Manganese - Yes Aggressive - Yes Turbidity - Low Organics - High Pathogens Taste & Odor

Three Step Process to Selecting Treatment Processes

Step 1 - Bench Scale Studies Step 2 - Pilot Plant Studies Step 3 - Finished Water Polishing

Structured Screening Process EstablishesViability of Alternates

ImpactsManageable?

ID Primary Impacts

Impacts?

Implement Testing &Further Evaluation

MitigationPossible?

EvaluateImpact

PossibleTreatmentStrategy

Develop MitigationStrategies

WillMitigation

Work?

SecondaryImpacts?

All ImpactsAddressed?

Abandon Strategy

Desktop Study

YES

YES

YES

YES

NOYES

Implement Testing &Further Evaluation

NO

NO

NO

NO

NOYES

STEP 1 - Bench Scale Studies Selects Processes for Further Evaluation

Review Historical Water Quality Data

Conduct Bench Scale Treatability Studies

Screen Potential Processes

Select Processes for Step 2 - Pilot Testing

Broken Arrow Settled Turbidity

0

1

2

3

4

5

6

7

10 20 30 40 50 60Ferric Sulfate Dosage, mg/L

Turb

idit

y, N

TU

Verdigris River Raw Water

Turb. = 10.6 NTU

Opt

imum

Dos

e

Lake Conroe Water

Aluminum Chlorohydrate Dose (mg/l)

STEP 2 - Pilot Studies Test Processes Under Real Life Conditions

Construct Pilot Plant Operate Pilot Plant Select/Rank Criteria Evaluate Processes against criteria Select Process for Full Scale Development

Filter Feed Tank

Ozone Contactor

Pall Microza Membranes

GE ZeeWeed 1000

Membranes

Bypass Stream

MIEXContactor

Conventional Filter

Static Mixer

Discharge Tank

Membrane Feed Tank

Kruger Ceramic Membranes

FromKruger Feed

Tank Overflow

From Plate Settlers

From Membrane Feed Tank Overflow

From Conventional

Feed Tank Overflow

From Cleaning Neutralization

Tank

From Conventional

Filter Backwash

From BAF Backwash

From GAC

From BW Tank Overflow

From BAF BW Tank Overflow

Gravity Discharge Collector

Static Mixer

BAFBAF

Feed Tank

From BAF Feed Tank Overflow

LakeConroe

Plate Settler

DischargeInfluent FromLake Conroe

GAC

Pilot Plant at Project Site

Pilot Plant at Project SitePlate Settlers

Pilot Plant at Project SiteMembrane Modules & GAC

MembraneFilters Activated Carbon

Filters (GAC)

Activated CarbonFilters (GAC)

Process Process Description

Train 1 Clarification + Conv. Filter

Train 1A Clarification + Conv. Filter + UV/H2O2

Train 1B Clarification + Conv. Filter + GAC

Train 2 PS + Ozone + BAF

Train 2A PS + Ozone/H2O2 + BAF

Train 3 PS + Polymeric Membranes

Train 3A PS + Polymeric Membranes + GAC

Train 3B PS + Polymeric Membranes + Organix

Train 3C MIEX + Polymeric Membranes

Train 3D MIEX + Polymeric Membranes + GAC

Train 3E PS + Polymeric Membranes + UV/H2O2

Train 4 Ceramic Membranes

Train 4A Ceramic Membranes + GAC

Train 4B Ceramic Membranes + UV/H2O2

Criteria Rank Criteria

1 Community Impact

2 Water Quality Aesthetics

3 Relative Capital Cost

4 O&M Requirements and Cost

5 System Robustness

6Water Integration Compatibility/Blending

Non-Proprietary Equipment

8 Safety and Environmental Site Impacts

9 Premium Pathogen Removal

10 System Simplicity

11 Area Required and Site Constraints

12 Regulatory Flexibility

13 Ease and Cost of Expansion

Colloids

Bacteria

Pollens Yeasts

Organic macromolecules

Viruses

MF

Sand filter

1 mm 0.1 mm 0.01 mm 0. 1 nm10 mm100 mm

hair visible to naked eye

Red globuleSmallest microorganisms Polio virus

UF

Particle Size Relationships

Microfiltration

UltrafiltrationConventionalFilters

Membranes

Relative Sizes of Small Particles

Pencil Dot (40 µm)

CryptosporidiumOocysts (3 - 6 µm)

Microfiltration (0.1 µm)

Giardia Cyst (5 - 15 µm)

Average size openingin a standard filter (60 µm)

20

Conventional vs. Membrane Filtration

Granular / Mixed Media

Irregular Pore Size Distribution (50 -70 micron between

grains)

Probable Filtration

Membrane Media

Controlled Pore Size Distribution (0.1 micron)

Absolute Filtration

STEP 3 – Finished Water Polishing

Water Blending Chemistry Analyses• Sample Water from Distribution System• Sample Pipes from Distribution System• Compare compatibility with proposed

treatment process Defines Required Water Chemistry

Adjustments

Finished Water Polishing ProvidesQuality Water AT THE TAP

Understanding What’s In the Pipe Leads to Compatible Water Chemistry

Iron scales represent a reservoir of metals, particulates, and biomass.

Chemistry changes in distribution system can release built-up deposits

Finished Water Chemistry Must be Compatible with Existing Infrastructure

Existing water is slightly aggressive

Minor corrosion scale No carbonate scale build-up Design water chemistry to

maintain existing corrosion scale

Pipe

Sam

ples

Fro

m C

onro

e

Treatment Techniques for Compatibility

Sodium Hydroxide: • Increase pH & alkalinity

Calcium Hydroxide:• Increase pH, alkalinity and

calcium Carbon Dioxide:

• Lower pH

Sam

ples

Fro

m T

he W

oodl

ands

All treatment chemicals are approvedby NSF for use in drinking water

Standard Indices Provide Goals for Post Treatment

The Langelier Saturation Index (LSI) Ryznar Stability Index (RSI) Calcium Carbonate Precipitation Potential

(CCPP) Larson Index (LI)

Post Treatment Provides Stable, Compatible Water to Consumers

Parameter Desired Value

Average Conditions

Current Treated

LSI > 0 -0.34 0.62

RSI < 7 8.27 6.97

CCPP 4 – 10 -3.99 5.48

Larson Index < 0.8 0.54 0.49

Sedimentation MembraneFiltration

Permanganate – Iron & Manganese

Calcium Hydroxide – pH and Alkalinity

Coagulant – TOC & Sediment Removal

Sodium Hydroxide – pH & Alkalinity

Chlorine - Disinfectant

D

Post Treatment& Polishing

1 2 3

A

B

C

A B C

1

2

3D

E

E

CHEMICAL TREATMENTPROCESSES

PHYSICAL TREATMENTPROCESSES

Sedimentation – Particulate and Organics Removal

Membrane Filtration – Particulate Removal

Activated Carbon – Organic contaminants removal

Selected Treatment Processes

Next Steps to Quality at the Tap

Acquire and analyze water samples from each receiving station – Refine post treatment plans as necessary

Identify treatment techniques currently used at existing utilities

Develop “Baseline Operations Report” at existing systems

Develop Guidelines to assist utilities to prepare for surface water

Summary

Federal & Texas Regulations dictate very high drinking water quality

Project Specific Standards drive compatibility with existing groundwater

Project focuses on “Quality at the Tap” Extensive testing of treatment techniques

and existing conditions provides real life results – not textbook “rules of thumb”

SURFACE WATER TREATMENT PLANT

Questions / Discussion