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 Trichloromethane - Chloroform Dibromochloromethane Tribromomethane - Bromoform Dichlorobromomethane Krasner, 2007
The DBP Dilemma Factors • Disinfection dosage • Disinfectant type – Cl, NH 2 Cl, ClO2, ozone • pH of the water • Ammonia • Bromide ion concentration • Contact time
Why Should We Care? Where is your w ater? 97.2% of Earth’s waters are saline 2.1% of Earth’s waters are bound in ice caps and glaciers 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
THM Trend During Construction
THM Volatility Brooke & Collins, 2009
Spray Stripping Pilot Demonstration
Spray Stripping Pilot Demonstration Nozzle Minimum THM Maximum THM Pressure Removal Removal 19 psi 24% 64% 32 psi 38% 62% Influencing Factors for THM Removal Droplet Travel Distance Droplet Diameter Water Temperature THM Species Present
Spray Stripping Pilot Demonstration
Ammonia vs THM Control Strategy
Ammonia vs THM Control Strategy THM/Ammonia - Top of CCB January - August 2013 120 100 80 THM Concentration (ug/l) 60 40 20 0 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 0.68 0.29 0.42 0.54 0.82 1.15 1.19 1.49 1.66 1.8 2.24 2.5 2.66 3.9 4.04 4.94 4.98 10.2 Ammonia Concentration (mg/l)
Tres Rios WRF
Centrate Addition Bench Test Ammonia Residual Results Elapsed Time Beaker 1, Beaker 2, Beaker 3, Beaker 4, Average, mg/L mg/L mg/L mg/L 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
Centrate Addition Bench Test Settling Characteristics ML Control Soln. ML + Centrate Soln. Elapsed Time Ammonia Turbidity Ammonia Turbidity mg/L mg/L mg/L 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
THM Diurnal Characteristics Diurnal TTHM 140 60 120 50 100 40 TTHM UG/L 80 MGD 30 60 20 40 10 20 0 0
Centrate Addition Bench Test Centrate Return Line Storage Tank Irrigation Timer Irrigation Valves CCB Secondary Clarifier NH3 THM
Diurnal Pilot Control Strategy 100 No Control 90 80 70 Valve #1 TTHM UG/L 60 50 MGD 40 30 Valve #2 20 10 0
THM vs Chlorine Demand
THM On-Line Analyzer TTHM Analyzer Performance 160 140 120 AMS-100 EPA 624 TTHM, UG/L 100 80 60 40 20 0
TTHM ug/L THM Reduction 100 120 140 160 20 40 60 80 0 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
Centrate Addition - Next Steps Centrate Return Line Storage Tank Variable Frequency Drive Pump CCB Secondary Clarifier NH3 THM
CRAO Laboratory
CRAO Laboratory
WEST Center Labs
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