Trihalomethane Control at Tres Rios WRF Jeff Prevatt Pima County - - PowerPoint PPT Presentation

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Trihalomethane Control at Tres Rios WRF Jeff Prevatt Pima County RWRD May 9, 2015 DBPs Haloacetic Acids NDMA Bromate Bromoacetic Acid Chloroacetic Acid Chlorite Dibromoacetic Acid Dichloroacetic Acid Trichloroacetic Acid Common THMs

SLIDE 1

Trihalomethane Control at Tres Rios WRF

Jeff Prevatt Pima County RWRD May 9, 2015

SLIDE 2

DBPs

Krasner, 2007

Tribromomethane - Bromoform Dibromochloromethane Dichlorobromomethane

Common THMs Haloacetic Acids

Dibromoacetic Acid Chloroacetic Acid Dichloroacetic Acid Trichloroacetic Acid Bromoacetic Acid

NDMA Bromate Chlorite

Trichloromethane - Chloroform

SLIDE 3

The DBP Dilemma

Factors

Disinfection dosage
Disinfectant type

– Cl, NH2Cl, ClO2, ozone

pH of the water
Ammonia
Bromide ion concentration
Contact time

SLIDE 4

Why Should We Care?

Where is your w ater?

2.1% of Earth’s waters are bound in ice caps and glaciers 97.2% of Earth’s waters are saline 0.6% of Earth’s waters are groundwater 0.1% of Earth’s waters reside in surface water and atmospheric moisture

DBPs Can Be Carcinogens

SLIDE 5

THM Trend During Construction

SLIDE 6

THM Volatility

Brooke & Collins, 2009

SLIDE 7

Spray Stripping Pilot Demonstration

SLIDE 8

Spray Stripping Pilot Demonstration

Nozzle Pressure Minimum THM Removal Maximum THM Removal 19 psi 24% 64% 32 psi 38% 62%

Influencing Factors for THM Removal

Droplet Diameter Droplet Travel Distance Water Temperature THM Species Present

SLIDE 9

Spray Stripping Pilot Demonstration

SLIDE 10

Ammonia vs THM Control Strategy

SLIDE 11

Ammonia vs THM Control Strategy

20 40 60 80 100 120 10.2 4.98 4.94 4.04 3.9 2.66 2.5 2.24 1.8 1.66 1.49 1.19 1.15 0.82 0.54 0.42 0.29 0.68 ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND ND THM Concentration (ug/l) Ammonia Concentration (mg/l)

THM/Ammonia - Top of CCB January - August 2013

SLIDE 12

Tres Rios WRF

SLIDE 13

Centrate Addition Bench Test

Ammonia Residual Results

Elapsed Time Beaker 1, mg/L Beaker 2, mg/L Beaker 3, mg/L Beaker 4, mg/L Average, mg/L

2 hr 0.782 0.629 0.591 0.521 0.631 3 hr 0.821 0.682 0.630 0.566 0.675 4 hr 0.870 0.738 0.690 0.620 0.730 5 hr 0.923 0.794 0.746 0.676 0.785

SLIDE 14

Centrate Addition Bench Test

Settling Characteristics

ML Control Soln. ML + Centrate Soln. Elapsed Time Ammonia mg/L Turbidity mg/L Ammonia mg/L Turbidity mg/L

0.5 hr 0.032 1.61 0.569 0.80 2.25 hr 0.055 0.57 0.549 0.90 3.25 hr 0.069 0.55 0.538 0.69 5.25 hr 0.083 0.57 0.514 0.63

SLIDE 15

THM Diurnal Characteristics

10 20 30 40 50 60 20 40 60 80 100 120 140

MGD

TTHM UG/L

Diurnal TTHM

SLIDE 16

Centrate Addition Bench Test

NH3 THM Secondary Clarifier CCB Irrigation Valves Irrigation Timer Storage Tank

Centrate Return Line

SLIDE 17

Diurnal Pilot Control Strategy

10 20 30 40 50 60 70 80 90 100

TTHM UG/L

No Control Valve #1 Valve #2

MGD

SLIDE 18

THM vs Chlorine Demand

SLIDE 19

THM On-Line Analyzer

20 40 60 80 100 120 140 160 TTHM, UG/L

TTHM Analyzer Performance

AMS-100 EPA 624

SLIDE 20

THM Reduction

20 40 60 80 100 120 140 160 11/25/2014 17:07 11/28/2014 12:01 11/30/2014 16:01 12/2/2014 20:01 12/5/2014 0:01 12/7/2014 4:01 12/9/2014 8:01 12/11/2014 12:01 12/14/2014 4:01 12/16/2014 8:01 12/18/2014 16:01 12/20/2014 16:01 12/22/2014 20:01 12/25/2014 0:01 12/27/2014 6:33 12/29/2014 20:01 1/1/2015 0:01 1/3/2015 4:01 1/5/2015 8:01 1/7/2015 12:01 1/9/2015 16:01 1/12/2015 12:01 1/14/2015 16:01 1/16/2015 20:01 1/19/2015 12:01 1/21/2015 16:01 1/23/2015 22:22 1/26/2015 12:01 1/28/2015 16:01 1/30/2015 20:01 2/2/2015 0:01 2/4/2015 4:01 2/6/2015 8:01 2/9/2015 0:01 2/11/2015 4:01 2/13/2015 8:01 2/15/2015 12:01 2/17/2015 16:01 2/19/2015 20:01 2/22/2015 12:01 2/24/2015 16:01 2/27/2015 16:01 3/1/2015 20:01 3/4/2015 0:01 3/6/2015 4:01 3/8/2015 8:01 3/10/2015 12:01 3/12/2015 16:01 3/15/2015 8:01

TTHM ug/L

SLIDE 21

Centrate Addition - Next Steps

NH3 THM Secondary Clarifier CCB Storage Tank

Centrate Return Line

Variable Frequency Drive Pump

SLIDE 22

CRAO Laboratory

SLIDE 23

CRAO Laboratory

SLIDE 24

WEST Center Labs

SLIDE 25

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fficial policy of the Association.”