UV Disinfection of Cryptosporidium for Newly Reclassified Bin 2 Systems in Illinois. Bryan Townsend UV Technology Leader B&V Water Technology Group

Transcription

1 UV Disinfection of Cryptosporidium for Newly Reclassified Bin 2 Systems in Illinois Bryan Townsend UV Technology Leader B&V Water Technology Group

2 Acknowledgements Coauthors Ben Freese (Black & Veatch) Beth Matthews (Illinois American Water) Illinois American Water (ILAW) Sarah Boyd Ian Rischmiller Rachel Bretz Randy Pankiewicz Illinois Environmental Protection Agency (IEPA) Matt Talbert David Cook 2

3 Illinois American Water Provides water and wastewater services to 1.3M consumers in >120 communities across IL 2 nd round LT2ESWTR source water monitoring Required six years after initial bin classification 4 Facilities reclassified from Bin 1 to Bin 2 1-log additional Crypto treatment Peoria, Alton, Granite City and East St. Louis Service Areas Black & Veatch retained to conduct a conceptual design study on potential solutions UV and ozone disinfection Illinois American Water Major Service Areas 3

4 UV Disinfection Drivers Familiar with UV technology Already installed at Peoria for Giardia inactivation Established track record and proven performance Very effective disinfectant for Crypto and Giardia at low doses Use as part of multi-barrier disinfection approach with chlorine/chloramines No DBP concerns Does not offer additional benefits (oxidation, T&O) unless paired with oxidant (Cl 2, H 2 O 2 ) for advanced oxidation Illinois River Station Control Building Peoria, IL 4

5 CT (mg-min/l) 1.5-log Crypto 40 2 o C log Giardia Ozone Disinfection Drivers Effective disinfectant with proven track record High CT for Crypto inactivation, esp. in cold water Provides numerous other treatment benefits* T&O control DBP reduction (oxidation of NOM) Improve filter performance (microflocculation) Temperature ( o C) Must consider bromate formation potential Several mitigation strategies exist *Key driver for ILAWs interest in ozone 5

6 Peoria Illinois River Station (IRS) Illinois River Station, Peoria, IL Google Earth 2018 Illinois River Station Peoria, IL Main treatment facility of Peoria, IL water system Also includes 3 groundwater treatment systems Serves Peoria, IL & adjacent areas (53K customers) 17.5 mgd surface water treatment plant Source water from Illinois River Coag/Floc Sedimentation Filtration Disinfection Multi-barrier disinfection UV: 0.5-log Giardia inactivation Chlorine: 2-log Virus CT Chloramines: Distribution system residual 6

7 Peoria IRS UV Facility 2+1 Calgon 3x10kW 24-inch Sentinel UV reactors Designed for 2-log Crypto inactivation 17.5 mgd, 86% UVT Microbial surrogate limited to MS2 1.3 interim ASCF Online in Jan / Permitted in Dec Permitted for 2-log Giardia credit IEPA reduced max. Giardia credit to 1.5-log in 2015 to reflect ASCF of 1.81 from WRF 4376 tables Ample capacity to provide Bin 2 Crypto requirements with potential for optimization of UV system operations Peoria IRS UV Facility 7

8 IEPA Consultation Opportunities for UV System Optimization Dose-monitoring approach / use of alternate surrogates T1UV and MS2 acceptable surrogates More robust data set required for T7 dose-response QA/QC bounds Action spectra correction factor approach WRF 4376 default ASCF or reactor-specific ASCF (with report approval) Design disinfection capacity Design capacity of 2-log Crypto for Bin 2 systems, ability to operate at 1.5 logi once facility gains comfort / familiarity with UV operations Use of T1UV and proper implementation of 4376 default ASCF results in Crypto disinfection capacity of 2.9 logi at Peoria IRS Peoria IRS UV Facility 8

9 Design Approaches Common to all WTFs UV DISINFECTION 2.0 logi Crypto target Influent source: filter effluent WRF 4376 default ASCF OZONE DISINFECTION 1.5 logi Crypto target, 2 o C = 31 mg-min/l CT Influent source: settled water Liquid oxygen (LOX) supply Closed loop cooling Surrogate: T1UV or MS2 n+1 reactor redundancy Sidestream O 3 injection 2 Contactors, 20 min HDT, 0.7 baffling factor (T 10 /T) n+1 generator redundancy LOX Tanks Grand Strand WSA Myrtle Beach WTP, SC 9

10 Alton WTF Serves Alton, IL & adjacent areas (19K customers) 16 mgd plant treating water from Mississippi R. Coag/Floc Superpulsator solids contact clarifiers Filtration Disinfection Disinfection: Chlorine/Chloramines: 2-log Virus & 0.5-log Giardia Chloramines: Distribution system residual Alton WTF, Alton, IL Google Earth

11 Cost $8M $6M $6.1M $4.8M Alton WTF UV Conceptual Design 3 design alternatives (84% UVT, 16 mgd) UV-1: Combined filter effluent $4M 2 (1 duty + 1 stdby) 24-in reactors $2.8M UV-2/3: Individual filter effluent (6 filters) UV-2: 1 x 12-in reactor per filter $2M 6 reactors total, 3.2 mgd/reactor UV-3: 2 x 12-in reactors per filter 12 reactors total, 1.6 mgd/reactor $0M UV-1 UV-2 UV-3 Lower head loss and redundancy at avg. flow 20-Year O&M Present Worth Total Project Cost Est. 11

12 Cost $24M $20M $19.9M Alton WTF Ozone Conceptual Design $16M $12M $8M $4M Bench-scale testing conducted on single sample* 7.7 mg/l O 3 dose 1+1 x 1,000 ppd generators (12% wt.) Residual quenching likely required (> 0.05 mg/l residual after 20 min HDT) Bromate formation a concern (> 10 µg/l MCL) >95% MIB and Geosmin removal at design dose $0M O Year O&M Present Worth Total Project Cost Est. *Additional testing required if O 3 selected as preferred technology to confirm initial results 12

13 Cost $24M $20M $16M $19.9M Alton WTF Conclusions UV is 3-7x less expensive than ozone = preferred disinfection technology $12M Alt. UV-2 not viable due to head loss concerns & lack of redundancy $8M $4M $0M $6.1M $4.8M $2.8M UV-1 UV-2 UV-3 O3-1 Alt. UV-3 viable $1.3M (21%) in est. project savings Alt. UV-1 recommended Fewer reactors to maintain (2 vs. 12 reactors) $350K 20-yr PW savings 20-Year O&M Present Worth Total Project Cost Est. 13

14 Granite City WTF Serves residents of Granite City, IL 14 mgd plant treating water from Mississippi R. Future peak flow of 20 mgd Pre-treatment Coag/Floc Sedimentation Filtration Disinfection Disinfection: Chlorine/Chloramines: 2-log Virus & 0.5-log Giardia Chloramines: Distribution system residual Granite City WTF, Granite City, IL Google Earth

15 Cost $8M $6M $4M $2M $0M $5.4M UV-1 $6.3M UV-2 Granite City WTF UV Conceptual Design 3.2 ft. of available head for UV facility 2 design alternatives (77% UVT, 14 mgd) UV-1: 2 (1 duty + 1 stdby) 24-in reactors 3.8 ft. head 14 mgd per reactor 1.7 ft. head 7 mgd per reactor = operate redundant reactor at high flows UV-2: 3 (2 duty + 1 stdby) 24-in reactors Redundant reactor offline at high flows 20-Year O&M Present Worth Total Project Cost Est. 15

16 Cost $24M $20M $19.0M $19.0M Granite City WTF Ozone Conceptual Design $16M $12M $8M $5.4M $6.3M Bench-scale testing conducted on single sample* 6.0 mg/l O 3 dose 1+1 x 750 ppd generators (12% wt.) Residual quenching likely required (> 0.05 mg/l residual after 20 min HDT) Bromate formation not a concern (< 1 µg/l MDL) $4M >80% MIB and Geosmin removal at design dose $0M UV-1 UV-2 O3-1 O Year O&M Present Worth Total Project Cost Est. *Additional testing required if O 3 selected as preferred technology to confirm initial results 16

17 Cost $24M $20M $19.0M Granite City WTF Conclusions $16M UV is >3x less expensive than ozone = preferred disinfection technology $12M Alt. UV-1 least expensive option $0.9M (16%) savings in est. project costs $8M $5.4M $6.3M $162K 20-yr PW savings Alt. UV-2 recommended $4M Lower head loss Redundant reactor at high flow rates $0M UV-1 UV-2 O Year O&M Present Worth Total Project Cost Est. 17

18 East St. Louis WTF Regional plant serving Metro East (68K customers) 56 mgd plant treating water from Mississippi R. Future peak flow of 75 mgd Two separate treatment trains Conventional & Aldrich unit treatment trains Disinfection: Chlorine/Chloramines: 2-log Virus & 0.5-log Giardia Chloramines: Distribution system residual East St. Louis WTF, East St. Louis, IL Google Earth 2018 Ozone not evaluated due to inability to treat settled water in Aldrich treatment train 18

19 Cost $80M $76M $74M $69M East St. Louis WTF UV Conceptual Design $60M 3 design alternatives (72% UVT, 56 mgd) UV-1/2: 3 (2 duty + 1 stdby) 48-in reactors $40M Alt. UV-1: Gravity flow, UV vault below grade Alt. UV-2: Pumped flow, UV facility above grade UV-3: 4 (3 duty + 1 stdby) 24-in reactors $20M Pumped flow, UV facility above grade Recommended option lowest cost alternative $0M UV-1 UV-2 UV-3 20-Year O&M Present Worth Project Cost Est. O&M includes cost of pumping 19

20 Current Status Peoria IRS UV Facility Working with IEPA on review/approval of new Calgon 24-in validation and ASCF reports East St. Louis conceptual design report complete RFP for detailed design and construction phase services issued on Jan. 24 (due Feb. 22) Alton and Granite City draft conceptual design reports under review by ILAW RFP for detailed design and construction phase services issued on Feb. 13 (due Mar. 7) All UV facilities to be operational by October 1,

21 THANK YOU