Existing Arsenic Treatment Systems in California: Performance and Cost Comparisons

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1 Existing Arsenic Treatment Systems in California: Performance and Cost Comparisons Liz Hilkert Jeannie Darby, Peter Green, & Thomas Young UC Davis Center for Affordable Technology for Small Water Systems (CATSWS) AWWA Regional Conference April 7, 2009

2 Outline Motivations and Focus Study Objectives Methodology Existing Arsenic Treatment Technologies Preliminary Performance and Cost Results Conclusions PICTURE 2

3 Motivations and Focus CATSWS mission: to provide technical assistance to help small, public water systems comply with minimum drinking water regulations, thereby increasing the availability of safe water for all Californians. Existing methods are not adequately estimating the total cost of an arsenic treatment system Experimental (e.g. pilot study, RSSCT) Empirical Modeling (e.g. Regression cost models - EPA & vendors) Case study approach with focus on small water systems serve between 25-3,300 people or service connections for at least 60 days per year State Small Water systems serve between 5-14 connections and less than 25 people 3

4 Study Objectives Characterize existing system operations Quantify capital and O&M costs Analyze data for cost and performance trends as a function of type of treatment Gather lessons learned from system contacts 4

5 Study Methodology System Selection: CDPH District Engineers identified 38 systems Means of Contact: Phone and Data Collection: 2 page questionnaire Analysis: In progress All systems are unique Data are not normally distributed 5

6 System Questionnaire General Information CDPH System Number System Name Contact Name & Phone District Startup Date Status Water Quality Influent As ( g/l) Effluent As goal ( g/l) Influent ph Known co-contaminants (e.g., silica, phosphate and vanadium) 6

7 System Questionnaire: Treatment Specifications Process description Manufacturer and model CDPH well numbers Issues Design capacity (gpm) Average flow (gpm) Loading rate (gpm/ft 2 ) Gallons treated per year Gallons treated per breakthrough Days to breakthrough System operation (hrs/day and days/yr) ph adjustment? Pre-oxidation? Empty bed contact time Backwash? Disposal Media bed life (#BVs) Regenerated or replaced? Disposal method 7

8 System Questionnaire: Costs Capital Total with description or Land Housing Pipes and storage Operating & monitoring equipment Media Testing (RSSCT or piloting) Permits Operator training O&M Total with description or Media replacement Media disposal Chemicals Repair and maintenance Power Labor $ Hours per day or week Analyticals Sludge disposal 8

9 Sample Case Study Information not readily available for many SWS. A few calculated O&M costs for the first time. 9

10 CA SWS: Current Arsenic Treatment Technologies Adsorption (17) Dow Adsorbsia GTO (1) Isolux Zirconium Hydroxide (1) Severn Trent Bayoxide 33 (13) Siemens GFH (1*) US Filter GFH (1*) Ion Exchange (7) Basin Water (6) Not reported (1*) Other (2) Layne LayneOx (1) Not Reported Green Sand (1*) Coagulation Filtration (17) Filtronics (2) Filtronics Electromedia (1) Hungerford & Terry (3) Kinetico (2) PureFlow, Inc (1) Tonka (1) Not Reported (5, 2*) Adsorption Coagulation Ion Exchange "Other" *Data provided to date are inadequate for analysis. 10

11 Design Flow Rate (gpm) Characterization of Surveyed Treatment Type Water Systems Average Arsenic Removed ( g/l) Total Adsorption 2 2 Coagulation Adsorption Coagulation Ion Exchange 1 3 Adsorption Coagulation Ion Exchange 2 12 Other 1 Total Average % of design flow used annually: Adsorption: 75% +/- 24% Coagulation: 83% +/- 25% Ion Exchange: 68% +/- 22% 11

12 Preliminary Correlations Test All data points included Variables tested Design flow Ave arsenic removed DPH reported Si, V, & P Expected & actual BVs to breakthrough Annual gallons treated Capital ($), ($/1000 gal), ($/g As removed) O&M ($/1000 gal), ($/g As removed) Significant at 0.01 level Ave arsenic removed & O&M ($/1000 gal): Expected Silica & expected BVs: Taken into account in design Ave arsenic removed & actual BVs: Data also shows fewer interferences as BVs increase Vanadium & annual gallons treated: Reason unclear. Small & large systems reported equally 12

13 Adsorption Systems: Representative Sample Ave System Flow (gpm) Arsenic Removed ( g/l) Discrepancy of Bed Volumes Capital Costs ($1000) Capital Costs ($/1000 gal) O&M ($/1000 gal) $53 $57.30 $ $16 $5.57 $ ,000 $300 $7.07 $ ,000 $209 $4.18 $0.45 Average cost of tap water is $1.60/1000 gal in CA & $2.00/1000 gal in the US (EPA 2008) ,300 $420 $17.50 $ ,000 $204 $11.00 $ ,000 $3,030 $16.30 $ ,500 $1,120 $4.15 $0.52 1, ,000 $1,000 $1.59 $0.19 1, ,000 $4,000 $5.29 $1.38

14 Ave System Flow (gpm) Coagulation Systems: Representative Sample Arsenic Removed ( g/l) Capital Costs ($1000) Capital Costs ($/1000 gal) O&M ($/1000 gal) $345 $1,580 $ NA NA $ $2,840 $86.00 $ $0.30 $0.01 $ $1,200 $22.60 $ $3,800 $60.30 NR NR NA $1.60 3, $8,200 $7.16 $0.24 4, $18,000 $7.63 $0.36 NR NR $2,940 $4.05 $0.58

15 Treatment Type Percentile Comparison Treatment Technology Capital Costs ($/1000 gal) Capital costs ($/g As removed) Normalized O&M ($/1000 gal) Normalized O&M ($/g As removed) Adsorption $5.43 $84 $1.31 $22 Coagulation $15.10 $199 $1.09 $19 Median Ion Exchange $4.74 $125 $1.24 $30 Other* $145 $1,490 $8.14 $83 Adsorption (13) $ $241 $12 - $3,860 $ $89 $ $151 Range Coagulation (8-9) $ $1,580 $ $92,500 $ $86 $ $7,580 Ion Exchange (6) $ $83 $45 - $2,310 $ $1.55 $ $44 Other (1) $145 - $145 $1,500 - $1,490 $ $8.14 $83 - $83 Average cost of tap water is $1.60/1000 gallons in CA and $2.00/1000 gallons in the US (EPA 2008) 15

16 Discrepancy b/w Expected & Actual Bed Volumes for Adsorption Ave Arsenic Removed (µg/l) Ave Arsenic Removed(ug/L) Ave Silica (mg/l) Ave Silica Concentration (mg/l) Ave Vanadium (µg/l) Ave Vanadium Concentration (ug/l) Ave Phosphate (µg/l) Ave Phosphates Concentration (ug/l) Contaminant Concentrations ,000 20,000 30,000 40,000 50,000 60,000 70,000 80,000 Bed Volume Discrepancy 16

17 Reported Water Quality System Count Weighted Average As ( g/l) /- 9.7 Si as SiO 2 (mg/l) /- 2.0 P as PO 4 (mg/l) /- 0.1 V ( g/l) /- 17 Fe ( g/l) /- 95 Mn ( g/l) /- 48 Monitoring potential interferents is critical to designing and operating an arsenic treatment system 17

18 $100 $90 $80 Adsorption Coagulation Ion Exchange Other $70 O&M ($/1000 gal) $60 $50 $40 $30 $20 $10 $0 $0 $200 $400 $600 $800 $1,000 $1,200 $1,400 $1,600 $1,800 Capital Costs ($/1000 gal) 18

19 $10 $9 $8 Adsorption Coagulation Ion Exchange Other $7 O&M ($/1000 gal) $6 $5 $4 $3 $2 $1 $0 $0 $50 $100 $150 $200 $250 Capital Costs ($/1000 gal) 19

20 Conclusions Tracking O&M costs and performance data is relatively new for most small systems. The cost of treating arsenic was found to be significant relative to the average cost of tap water in CA and in the US. Huge variation found in costs, water quality and performance across surveyed systems. Monitoring interferents as well as arsenic concentrations is critical to optimal system design and operation. 20

21 Acknowledgments CATSWS Colleagues Wei Hsiang Chen Ben Erker California Department of Public Health Richard Haberman, P.E. Dat Tran, P.E. District Engineers This research was funded through the California Department of Public Health Safe Drinking Water Revolving Fund Contract # The findings expressed do not necessarily reflect the funding agency s views. 21

22 Questions? Liz Hilkert The report, including case study appendices, should be available online by late June at: 22

23 Lessons Learned from System Contacts Manage expectations Historic arsenic and possible interference contamination data are critical to designing a system Create implementation timelines and budgets that allow for pilot testing (or RSSCT tests during multiple times of the year) Complete a cost benefit analysis of all alternatives before a treatment is chosen New irrigation infrastructure Understand the fine print of service contracts and warranties prorated prices and maintenance schedules 23

24 Lessons Learned (Part 2) Understand hazardous waste disposal issues Piloting at another site is essentially useless at new site if the raw water quality is different Managing coagulation filtration systems can be a challenge if arsenic samples need to be sent to the lab frequently Turnaround time is usually a few weeks 24