Water Quality in the Distribution System

Syed A. Imran

The Drinking Water The Drinking Water ContinuumContinuum

Drinking Water TreatmentDrinking Water Treatment

SourcesSourcesGroundwaterSurface WaterSea Water

Distribution and Collection InfrastructureDistribution and Collection Infrastructure

Wastewater TreatmentWastewater Treatment

What is a Distribution System?

Photo Courtesy of Jorge Royan

Where is our Distribution System?

You wont see it You wont see it -------- Till its gone!Till its gone!

Need for Protection of Distribution System

Source: Environment Canada

What Causes this?

Internal Corrosion in Old Iron Pipes

Passive Film

Porous Corrosion Scales

ClCl--

Iron (hydro) oxidesIron (hydro) oxides

OO22 + H+ H22OO

FeFe2+2+

OO22 + H+ H22OO

ClCl-- + H+ H22OO

ee-- ee--

Fe(OH)Fe(OH)++ + + ClCl-- + H+ H++

Highly Anodic RegionHighly Anodic Region

Water Quality Interactions with Pipe Surfaces

FeFe+2+2

½½ OO22 OHOH--

OHOH--

GRGR

ClCl--

FeClFeCl22

NONO33--

FeOOHFeOOH

SOSO44--22

FeSFeS

HCOHCO33--

FeCOFeCO33

ee--AnodeAnode

CathodeCathode

Microbiological (biofilm) Interactions with Pipe Surfaces

Slime formers & Iron bacteria

ClCl--

FeFe2+2+

OO22

FeFeClCl33 Fe(OH)Fe(OH)33

OHOH-- FeFe2+2+

FeFe3+3+

HH22SS

SRBSRB

FeFeSS

GallionellaGallionella

ThiobacillusThiobacillusFeCOFeCO33

SOSO4422--

Highly Anodic RegionHighly Anodic Region

A picture is worth …

TBW groundwater protection targets -How to reconcile new sources with old pipes?

Before 2002

Construction of Pilot Site$ 3,000,0003,000,000 Tailored Collaboration Project

Tampa Bay WaterAwwaRFUniversity of Central Florida

Pilot Distribution System (PDS) Setup

Nominal length of PDS - 100 feet

Old pipes excavated and transported from actual distribution system

18 PDS constructed - 14 of which were identical

Pilot Distribution System

Lead and Copper Loops

Headworks

Pilot Water Treatment Processes

Nanofiltration Unit Coagulation and Settling UnitReverse Osmosis Unit

Softening and Filtration Units Sludge Drying Bed Field Laboratory

Mitigation measures for red water release control

0

25

50

75

50 100 150 200 250Alkalinity (mg/L as CaCO3)

∆C (C

PU)

HRT = 5 days HRT = 2 days

Alkalinity = 80 mg/L as CaCO3

Conflicting Water Quality Impacts on Different Pipe Materials

Copper Lead ColorAlkalinity ↑↑ ↑↑ ↓↓ ↓↓

↑↑↑↑

pH ↑↑ ↓↓ ↓↓ ↓↓Temperature ↑↑ ↑↑ ↑↑ ↑↑HRT ↑↑ ↑↑

Chlorides ↑↑ ↑↑ ↑↑Sulfates ↑↑ ↑↑ ↓↓

0

20

40

60

00.5

1

1.520

5

10

15

20

25

Definition of blend response [100% RO]

100% RO

Apparent Color Release

CPU

Copper Releasemg/L

Lead

Rel

ease

µg/L

35 CPU0.3 mg/L

16 µg/L

0

20

40

60

00.5

1

1.520

5

10

15

20

25

Definition of blend response [100% SW]

100% SW

Apparent Color Release

CPU

Copper Releasemg/L

Lead

Rel

ease

µg/L

13 CPU0.4 mg/L

1 µg/L

0

20

40

60

00.5

1

1.520

5

10

15

20

25

Definition of blend response [100% GW]

100% GW

Apparent Color Release

CPU

Copper Releasemg/L

Lead

Rel

ease

µg/L

2 CPU

1.2 mg/L

8 µg/L

010

2030

40

00.5

1

1.520

5

10

15

20

Feasible blends

100% RO

100% SW

100% GW

Apparent Color Release

CPU

Copper Releasemg/L

Lead

Rel

ease

µg/L

Impact of Distribution Pipes on Disinfectant Decay: Bulk Water and Pipe Wall Reactions

tKKt

wbeCC )(0. +=

)eTemperatur Quality, Water Residual,(fKb =

)Interface ofCondition Material, Pipe Quality, Water Residual,(fKw =

• Kb is the bulk reaction coefficient• Kw is the wall reaction coefficient

Chlorine vs. Chloramines

Time

Res

idua

l Dis

infe

ctan

t

Chlorine (6") Chloramine (6")Chlorine (48") Chloramine (48")

Examining the Effect of Water Quality on Integrity of Distribution Infrastructure

• NRC – AWWARF Collaborative Project– Linking water quality changes to integrity of distribution systems– “Talking Heads” – Getting experts together for a 1 Day

workshop at NRC Ottawa in March 2005

• Development of a Drinking Water Distribution Laboratory at the Center for Sustainable Infrastructure Research (CSIR), Regina

Distribution System Water Quality Laboratory

~ 20 ft Test Pipe

Lead

and

Cop

per C

oupo

ns

Water Quality Sensors & Sampling PortsVariable Flow DeviceFlow Control ValvesDirection of Flow

Chemical Addition PLC Controller

Data Recorder

VFD

Distribution System Water Quality Laboratory

Hydraulic parameters can be controlled using VFD’s

Online measurement and data-logging

Laboratory scale simulation of actual distribution systems

Test pipes can be changed for different material, age, degree ofcorrosion and locations

Additional ports for Lead and Copper, biofilms or surface characterization coupons

Biological control, disinfectant dynamics and persistence of pathogens can be studied

Enabling Drinking Water Enabling Drinking Water Sustainability in Small Sustainability in Small CommunitiesCommunitiesNRC 2006 Vision: Science at work for CanadaNRC 2006 Vision: Science at work for Canada

Support and enable drinking water systems towards self-sufficiency

Conduct demonstration and verification of emerging technologies

Develop and sustain innovative methods of maintaining safe drinking water in the distribution systems

Partner with federal, provincial and local governing bodies to identify and investigate research needs

What is the difference between this picture…

And this?

2424 Hours