Chlorine Dioxide One Year Later Shazelle Terry Treatment & WQ Department Manager
Presentation Agenda Background JVWTP Chlorine Dioxide History JVWTP Full Scale Implementation Results Summary 2
Chlorinated Disinfection Byproducts Chlorine + Organic Matter = Byproducts Regulated Byproducts Tri Halo Methanes (regulated at 80 ppb) Halo Acetic Acids (regulated at 60 ppb) Stage I DBPR System wide RAA Stage II DBPR Location specific RAA Background History Implementation Results Summary3
Investigating Alternatives Criteria Stop Pre Chlorination Potential Taste & Odor Control Reduce Post Chlorination Increase Disinfection Capacity Maintain or Improve Treatment Goals Background History Implementation Results Summary4
Chlorine Dioxide Greenish-yellow gas with chlorine-like odor Always manufactured at point of use as a water solution Extremely powerful and selective oxidizing agent True dissolved gas in solution - does not react or hydrolyze - ph independent Regulated byproduct is chlorite Background History Implementation Results Summary5
Pilot Study Completed Four Trials DBP formation did not occur until after the addition of free chlorine Finished DBP formation reduced 35-50% Did not appear to reduce TOC No negative coagulation effects Best feed location upstream of rapid mix (5-10 minutes) Background History Implementation Results Summary6
Full Scale Study Ran for 14 months 0.1 mg/l ClO 2 dose Eliminated KMnO 4 Eliminated pre-chlorination Monitored THMs, HAAs, and Chlorite and Chlorate Background History Implementation Results Summary 7
Two Chemical Chlorine Dioxide Generator Background History Implementation Results Summary 8
Chlorine Dioxide Dosing Locations Background History Implementation Results Summary 9
Prior to chlorine dioxide With chlorine dioxide Chlorine 12 Rapid Mix 0 ClO 2 Rapidly forming THMs (μg/l) Coagulation 30 1 36 40 Sedimentation Filtration 1 17 Chlorine Increasing Organics Removal Chlorine 40 Clearwell 19 Chlorine Background History Implementation Results Summary 10
During JVWTP Full-Scale Testing Chlorine Dioxide Reduced THM Formation Significantly Background History Implementation Results Summary 11
Capital Cost <10% O&M Cost 42% more Background History Implementation Results Summary12
Finally! Basics History Implementation Results Summary 13
Making Progress Basics History Implementation Results Summary 14
Feed location valving Modified Existing Chlorine System Basics History Implementation Results Summary 15
Basics History Implementation Results Summary 16
Basics History Implementation Results Summary 17
Part 2 Terminal Reservoir Cl2 Booster Completed Summer 2012 Sodium Hypochlorite 0.3 mg/l Cl 2 dose Reduced JVWTP post chlorine dose from 1.1 to 0.65 mg/l Basics History Implementation Results Summary 18
Terminal Reservoir Chlorine Booster Basics History Implementation Results Summary 19
Did it work? Basics History Implementation Results Summary 20
Basics History Implementation Results Summary 21
Basics History Implementation Results Summary 22
Basics History Implementation Results Summary 23
Basics History Implementation Results Summary 24
Effect on Member Agencies 90 City A THMs 80 70 60 50 40 30 20 10 0 4/18/2012 4/14/2008 City A HAA5 50 45 1 2 3 4 5 6 7 8 40 35 30 25 4/18/2012 20 4/14/08 15 10 5 0 1 2 3 4 5 6 7 8 Basics History Implementation Results Summary 25
Effect on Member Agencies 70 City B THMs 60 50 40 30 20 10 7/23/2012 6/10/2008 8/12/2008 70 City B HAA5 0 1 2 3 4 5 6 7 8 60 50 40 30 20 7/23/2012 6/10/2008 8/12/2008 10 0 1 2 3 4 5 6 7 8 Basics History Implementation Results Summary 26
Effect on Member Agencies System Cl 2 Basics History Implementation Results Summary 27
The Undesired Consequences Basics History Implementation Results Summary 28
The Undesired Consequences Basics History Implementation Results Summary 29
Summary Preparation is key Expect the unexpected Collect/Analyze a thorough dataset Basics History Implementation Results Summary 30