Chlorine Dioxide One Year Later. Shazelle Terry Treatment & WQ Department Manager

Transcription

1 Chlorine Dioxide One Year Later Shazelle Terry Treatment & WQ Department Manager

2 Presentation Agenda Background JVWTP Chlorine Dioxide History JVWTP Full Scale Implementation Results Summary 2

3 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

4 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

5 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

6 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

7 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

8 Two Chemical Chlorine Dioxide Generator Background History Implementation Results Summary 8

9 Chlorine Dioxide Dosing Locations Background History Implementation Results Summary 9

10 Prior to chlorine dioxide With chlorine dioxide Chlorine 12 Rapid Mix 0 ClO 2 Rapidly forming THMs (μg/l) Coagulation Sedimentation Filtration 1 17 Chlorine Increasing Organics Removal Chlorine 40 Clearwell 19 Chlorine Background History Implementation Results Summary 10

11 During JVWTP Full-Scale Testing Chlorine Dioxide Reduced THM Formation Significantly Background History Implementation Results Summary 11

12 Capital Cost <10% O&M Cost 42% more Background History Implementation Results Summary12

13 Finally! Basics History Implementation Results Summary 13

14 Making Progress Basics History Implementation Results Summary 14

15 Feed location valving Modified Existing Chlorine System Basics History Implementation Results Summary 15

16 Basics History Implementation Results Summary 16

17 Basics History Implementation Results Summary 17

18 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

19 Terminal Reservoir Chlorine Booster Basics History Implementation Results Summary 19

20 Did it work? Basics History Implementation Results Summary 20

21 Basics History Implementation Results Summary 21

22 Basics History Implementation Results Summary 22

23 Basics History Implementation Results Summary 23

24 Basics History Implementation Results Summary 24

25 Effect on Member Agencies 90 City A THMs /18/2012 4/14/2008 City A HAA /18/ /14/ Basics History Implementation Results Summary 25

26 Effect on Member Agencies 70 City B THMs /23/2012 6/10/2008 8/12/ City B HAA /23/2012 6/10/2008 8/12/ Basics History Implementation Results Summary 26

27 Effect on Member Agencies System Cl 2 Basics History Implementation Results Summary 27

28 The Undesired Consequences Basics History Implementation Results Summary 28

29 The Undesired Consequences Basics History Implementation Results Summary 29

30 Summary Preparation is key Expect the unexpected Collect/Analyze a thorough dataset Basics History Implementation Results Summary 30

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