Anion Exchange and GAC Demonstration for TOC Removal and THM Control

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1 Anion Exchange and GAC Demonstration for TOC Removal and THM Control Rick Schantz, Retired Village of Archbold Marvin Gnagy, P.E., President PMG Consulting, Inc. Project by URS Corporation Ohio Section AWWA September 22, 2011

2 Agenda Archbold Water Treatment Process Historical DBP Data IDSE Monitoring Suspected Source Water Changes Demonstration Study Objectives Anion Exchange Columns GAC Columns 2

3 Agenda Anion Exchange Resin Selection Demonstration Study Results Blended Water Quality SDS -THM Monitoring Operating Cost Comparison Current Project Status 3

4 Archbold Water Treatment Process 5 mgd surface water plant with lime soda softening 4

5 Archbold Water Treatment Process Large Reservoir Two Reservoirs filled from Tiffin River Small Reservoir Large Reservoir 200 MG Small Reservoir 100 MG TOC mg/l UV cm -1 SUVA L/mg-m KMnO 4 added when reservoirs being filled Raw Water Pump Station 5

6 Archbold Water Treatment Process KMnO 4 reaction oxidation of organics 30 minutes oxidation Activated carbon adsorption taste / odor control 30 minutes adsorption Solids Contact Clarification FeCl 3 enhanced coagulation Lime / caustic soda enhanced softening TOC removal 55% through clarification 6

7 Archbold Water Treatment Process Recarbonation CO 2 gas currently being converted to carbonic acid feed and automation added Dual Media Filtration Run times about 110 hours GWP 12,540 gal / ft 2 / run FE 0.04 NTU Currently meeting DBP requirements Through 3 rd quarter 2010 TOC reduction 61% RAA THM 62.5 µg/l RAA HAA µg/l 7

8 Historical DBP Data Continuous compliance with Stage 1 D/DBP Rule limits Slightly increasing THM running annual averages (RAA) from 2007 through 2010 Enhanced coagulation / enhanced softening no longer as effective for TOC reduction Possible difficulty meeting Stage 2 THM limits IDSE monitoring confirmed possible THM issues 8

9 Running Annual Average TTHM, ug/l Anion Exchange and GAC Demonstration for TOC Removal and THM Control Historical DBP Data (THMs only)

10 IDSE Monitoring - THM Data Only µg/l Concentrations Period SM-1 SM-2 SM-3 SM-4 2Q Q Q Q LRAA OELs OELs

11 TOC (mg/l) or SUVA (L/mg-m) Anion Exchange and GAC Demonstration for TOC Removal and THM Control Suspected Source Water Changes Year Poly. (TOC) Poly. (SUVA) Source TOC and SUVA Declining TOC now 18% lower than historical levels Pre mg/l 2007 on 5.5 mg/l SUVA now 9% lower than historical levels Pre L/mg-m 2007 on 2.42 L/mg-m Possible shift in organic character due to watershed changes 11

12 SUVA (L/mg-m) Anion Exchange and GAC Demonstration for TOC Removal and THM Control Suspected Source Water Changes Transphilic acids (TPHA) Fulvic Acids (FA) % Aromatic Carbon Humic Acids (HA) 12

13 SUVA (L/mg-m) Anion Exchange and GAC Demonstration for TOC Removal and THM Control Suspected Source Water Changes Transphilic acids (TPHA) Fulvic Acids (FA) Before % Aromatic Carbon Humic Acids (HA) 13

14 SUVA (L/mg-m) Anion Exchange and GAC Demonstration for TOC Removal and THM Control Suspected Source Water Changes After 2007 Transphilic acids (TPHA) Fulvic Acids (FA) Before % Aromatic Carbon Humic Acids (HA) 14

15 Demonstration Study Objectives Reduce finished water TOC to 1.7 mg/l or less TOC about 2.2 mg/l Reduce UV 254 to cm -1 or less Absorbance values about cm -1 Close correlation and quicker results than TOC Filtered water used as feed water for post filter adsorption demonstration 8 consecutive runs per resin column GAC operating parameters 15

16 Anion Exchange Columns 0.5 L Pilot Columns Regenerated with salt Regeneration time 45 minutes 3 detention times rinsed with feed water before initiating next run cycle HLR up to 8.7 gpm / ft 2 16

17 GAC Columns 10 minute and 20 minute EBCTs Packed with virgin carbon (100 x 200 mesh) Sampled after each column Operated to 2.0 mg/l TOC breakthrough HLR up to 10 gpm / ft 2 17

18 Anion Exchange Resin Selection Type I strong base anion (SBA) resins designed for TOC and organics adsorption Regeneration with NaCl or NaOH Equilibrium reactions at resin surface or adsorbed through porous membrane DOWEX MARATHON 11 Type I SBA porous styrene divinylbenzene gel 1.3 eq/l exchange capacity Thermax Tulsion A72-MP Type I macroporous polystyrene copolymer 1.0 eq/l exchange capacity 18

19 Anion Exchange Column Results 19

20 TOC, mg/l Anion Exchange and GAC Demonstration for TOC Removal and THM Control DOWEX MARATHON 11 Resin (1.3 eq/l) ,000 1,100 1,200 1,300 1,400 Bed Volumes Throughput TOC Breakthrough Curve 8.7 gpm / ft 2 ph 7.67 TA 10 mg/l UV cm -1 TOC 0.64 mg/l SUVA 1.3 L/mg-m THMFP 26.4 µg/l 81 hours per cycle 1,250 bed volumes per cycle Max TOC 1.5 mg/l TOC reduction 73.3% 20

21 TOC, mg/l Anion Exchange and GAC Demonstration for TOC Removal and THM Control Tulsion A72 - MP Resin (1.0 eq/l) ,000 1,100 1,200 1,300 1,400 Bed Volumes Throughput TOC Breakthrough Curve 8.6 gpm / ft 2 ph 7.65 TA 9 mg/l UV cm -1 TOC 0.56 mg/l SUVA 1.6 L/mg-m THMFP 22.7 µg/l 82 hours per cycle 1,207 bed volumes per cycle Max TOC 1.3 mg/l TOC reduction 76.7% 21

22 Blended Water Results 60% AEX Effluent / 40% Feed 22

23 Blended Water Quality (AEX and Feed) Comparison of Blended Water after Anion Exchange Parameter Marathon 11 A72-MP Water ph T. Alkalinity P. Alkalinity 9 9 Carbonates Bicarbonates 7 7 UV TOC SUVA THMFP TOC reduction, %

24 GAC Contactor Results 24

25 TOC, C/Co Anion Exchange and GAC Demonstration for TOC Removal and THM Control GAC RSSCT Contactors ,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 18,000 20,000 Bed Volumes Throughput EBCT 10 EBCT 20 Normalized TOC Breakthrough Curve 17,000 bed volumes at EBCT 10 21,850 bed volumes at EBCT 20 Breakthrough to ± 70% of influent concentration expected Expected life 330 days 25

26 GAC Usage Rate, lbs. GAC / 1,000 gallons Anion Exchange and GAC Demonstration for TOC Removal and THM Control GAC RSSCT Contactors TOC Treatment Objective, mg/l EBCT 10 EBCT 20 Carbon Usage Rate Curve Usage based on 2.0 mg/l TOC breakthrough EBCT pounds per 1,000 gallons EBCT pounds per 1,000 gallons 26

27 SDS-THMs AEX Blended Water Normal ph, normal free chlorine residual Feed water used as comparison with treated samples 72 hour average residence time 144 hour maximum residence time (MRT) Two consecutive systems served by Archbold 27

28 SDS-THMs AEX Blended Water SDS-THM Results µg/l Concentrations Period Feed MAR 11 A72-MP TOC, mg/l UV 254, cm SDS-THM

29 SDS-THMs AEX Blended Water SDS-THM Results µg/l Concentrations Period Feed MAR 11 A72-MP TOC, mg/l UV 254, cm SDS-THM TOC UV 254, cm SDS-THM

30 SDS-THMs AEX Blended Water SDS-THM Results µg/l Concentrations Period Feed MAR 11 A72-MP TOC, mg/l UV 254, cm SDS-THM TOC, mg/l UV 254, cm SDS-THM TOC, mg/l UV 254, cm SDS-THM Period hour residence time 30

31 SDS-THMs GAC Contactors SDS-THM Results µg/l Concentrations Feed GAC 1 GAC 2 GAC 3 TOC, mg/l UV 254, cm SDS -THM ph 8.8 Initial feed water 31

32 SDS-THMs GAC Contactors SDS-THM Results µg/l Concentrations Feed GAC 1 GAC 2 GAC 3 TOC, mg/l UV 254, cm SDS -THM ph 8.8 Initial feed water SDS -THM, ph

33 SDS-THMs GAC Contactors SDS-THM Results µg/l Concentrations Feed GAC 1 GAC 2 GAC 3 TOC, mg/l UV 254, cm SDS -THM ph 8.8 Initial feed water SDS -THM, ph SDS -THM 144 hour GAC replaced before 1.7 mg/l breakthrough full-scale operation 33

34 Operating Cost Comparison November 2010 Dollars Cost MAR 11 A72-MP GAC Annual $71,723 $57,436 $175,179 Cost per MG $ $82.82 $ Cost per 1,000 gallons $0.103 $0.083 $

35 Operating Cost Comparison November 2010 Dollars Cost MAR 11 A72-MP GAC Annual $71,723 $57,436 $175,179 Cost per MG $ $82.82 $ Cost per 1,000 gallons $0.103 $0.083 $0.253 Anion exchange about 1/3 operating cost of GAC 35

36 Current Status Obtained OEPA general plan approval Spring 2011 Designing anion exchange post filtration system January 2013 compliance deadline Blend anion exchange with filter effluent Finished TOC less than 1.7 mg/l Meets LRAA 80 µg/l or less Meets OELs ph monitoring anion exchange effluent Indicates bicarbonate breakthrough Signals regeneration cycles 36

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Enhanced Organic Precursor Removals Using Aged Filter Media Page 1. Enhanced Organic Precursor Removals Using Aged Filter Media

Enhanced Organic Precursor Removals Using Aged Media Page 1 Enhanced Organic Precursor Removals Using Aged Media O b j e c t i v e s The main goals of this project was to evaluate the dissolved organic