A Comprehensive Performance Evaluation (CPE) Approach to Addressing HABs

Transcription

1 A Comprehensive Performance Evaluation (CPE) Approach to Addressing HABs CPE Participants U.S. EPA: Alison Dugan, Tom Waters, Rich Lieberman, Craig Patterson, Val Bosscher Process Applications, Inc.: Larry DeMers and Bill Davis Ohio EPA: Heather Raymond, Ryan Bertani, Taylor Browning, Russel Flagg, Maria Lucente, Judy Stottsberry, Mariano Haensel, Gunaseelan Alagappan, Brandon Trigg, Kimberly Burnham, Gina Hayes, Ruth Briland, Katie Anderson, Rebecca Werner, Michael Carper, Brian Chitti

2 Overview Comprehensive Performance Evaluation (CPE) process Results of HAB CPE Pilots, Special Studies, & Lessons Learned

3 HAB CPE Pilot Project Development Partnering with USEPA & Process Applications, Inc. Series of 4 pilot HAB CPEs at Ohio WTPs 3 out of 4 Pilot HAB CPEs Completed as of July, 2017 Develop protocol for conducting a HAB CPE by modifying the existing microbial CPE guidance Transfer capability to conduct CPEs from USA and Consultants to Ohio EPA staff

4 Applying the CPE to Address Cyanotoxins Utilize CPE protocol to Optimize Existing Facilities for Particle Removal 50-95% of cyanotoxins are typically intracellular Avoid/Minimize pre-oxidation and release of cyanotoxins Utilize Multiple Barrier Approach to achieve USEPA health standards for microcystins (and thresholds for saxitoxins) Optimize cyanobacteria cell removal through improved coagulation, sedimentation and filtration processes Identify and assess strategies for extracellular microcystins removal or destruction through adsorption and oxidation processes.

5 Multiple Barrier Protection in the Water Treatment Plant Cyanobacterial cell removal (turbidity, particle counts, phycocyanin, chlorophyll-a, DOC, UV254, color, other) Coagulation/flocculation + sedimentation + filtration Cyanotoxin removal (ELISA, LC-MS/MS) Powdered Activated Carbon (PAC) Addition Advanced Treatments (Granular Activated Carbon (GAC), Ozone, UV, etc.) Oxidation: Contact Time (CT) for pathogen inactivation and cyanotoxin oxidation Variable Quality Source Water Coagulant Addition Disinfectant Addition Coagulation Flocculation Sedimentation Barrier Filtration Barrier High Quality Finished Water Disinfection Barrier

6 Comprehensive Performance Evaluation Solution Develop approaches to assess why a treatment plant may not be performing as desired Develop an advisory to help operators better utilize their treatment facilities Achieve optimum performance using existing infrastructure

7 Defining a Plant Capable of Optimization: the Fundamental Approach to Water System Optimization Optimized Performance Goals Process control: Anything needed to create a capable plant and achieve optimized performance Operation/Process Control Capable Plant Design Administration Operations and Maintenance

8 1.Assessment of plant performance Historical data Data collected during CPE CPE Major Components 2.Evaluation of major unit processes (MUP) Flocculation, sedimentation, filtration, and disinfection Based on capability to handle peak instantaneous flow requirements. Develop a performance potential graph. Rating system for adequacy of each major treatment process and overall plant. 3.Identification and prioritization of performance-limiting factors (PLFs) Administrative, design, operation and maintenance categories PLF prioritization ratings 4.Reporting results of the evaluation

9 Case Study #1: Lake Erie PWS Conventional treatment (coagulation, flocculation, sedimentation, filtration) Powdered Activated Carbon (PAC) NaMnO 4 pre-oxidation Gaseous chlorine disinfection

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11 Permanganate Jar Testing Jar # Coagulant (ACH) dose Permanganate dose 1 (control) None None 2 24 mg/l (plant s dose) None 3 24 mg/l (plant s dose) 1.2 mg/l (plant s dose) 4 24 mg/l (plant s dose) 3 mg/l (high dose where cyanotoxin release may occur

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13 Plant Profile Sampling

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16 Case Study #1 Lessons-Learned: Value of plant profile in understanding capability of each unit process Difficulty in estimating PAC capacity isotherms underreport likely due to competing organics in actual raw water Performance-limiting factors identified were not necessarily tied to HABs and have a significant impact on WTP operations as a whole

17 Case Study #2: Southeast Inland Lake PWS In-stream reservoir Conventional treatment with lime-soda softening Recarbonation ph adjustment out of service PAC addition at raw water intake and rapid mix Gaseous chlorine disinfection

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19 PAC Jar Testing Evaluate microcystins removal capacity of PAC Control No PAC Increasing PAC Dose 40 mg/l PAC

20 PAC Jar Testing Coal-based PAC added at raw water pump station 24 hour travel time to WTP Determine adsorption capacity at various PAC doses Plant dose ~ 17 mg/l of PAC Microcystins Dose: Intracellular 23 ug/l Extracellular 11 ug/l

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23 Filter Evaluation: Excavation & Performance Filter media Anthracite & sand

24 Major Unit Process Evaluation

25 Case Study #2 Lessons-Learned Performance-limiting factors identified were not necessarily tied to HABs and have a more continuous impact on plant operations Difficulty in Estimating PAC Capacity Jar testing protocol to help with MUP evaluation may be needed Chemicals fed alongside of PAC may impact its ability to remove cyanotoxins Further studies to be considered for the future Microcystin Oxidation Evaluations made based on the AWWA calculator may vary at higher ph levels Further studies regarding chlorine residuals and disinfection may be need

26 Case Study #3: Southwest Inland Lake PWS In-stream reservoir Conventional treatment with lime-soda softening Recarbonation ph adjustment PAC addition at the rapid mix Gaseous chlorine disinfection

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29 FTW Time (Hr:Min) January 2017 Filter to Waste Times 7:12 6:00 Long filter to waste times were required in January to reduce turbidity to < 0.30 NTU following filter backwashes. High settled water turbidity (95th percentile was 35 NTU in January) and possibly low water temperatures likely contributed to these long filter to waste times (average > 2 hours, maximum > 6 hours). Typical filter to waste times in an optimized plant are less than 30 minutes. 4:48 3:36 2:24 1:12 0:00 1A FTW 1B FTW 1C FTW 1D FTW 2A FTW 2B FTW 2C FTW 2D FTW Average Maximum Minimum Typical

30 Special Study: Jar Tests

31 Jar Test Setup *Done Using Both Wood and Coal Based PAC*

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33 Filter Assessment

34 Calcium Carbonate Buildup on Trough Bottoms Media: anthracite and sand mixed together with intermixed pieces of calcium carbonate. Three evaluations: 26 to 32 inches deep

35 Major Unit Process Evaluation - City of Wilmington Water Treatment Plant Turbidity Removal (microbes, cells) and Disinfection Caesar Creek Intake 2.23 Peak Instantaneous Flow MGD Cowan Creek Intake 2.00 Flocculation 4.03 Sedimentation 9.29 Conventional Filtration 4.03 Disinfection (Giardia Inactivation)

36 Major Unit Process Evaluation - City of Wilmington Water Treatment Plant Microcystins Adsorption PAC Feed (Current) (A) 0.75 Peak Instantaneous Flow MGD PAC Feed (Potential) (B) (A) Under the current configuration, the plant can treat up to 0.75 MGD at the 40mg/L recommended dosage for PAC. (B) This option considers using two large screws rated at 1330 lb/day each are available at the plant. The current feeder piping is subject to clogging and would need to be reconfigured. The second feeder would also need to be placed into service. Note: PAC feed potential at the Caesar's Creek Intake was also evaluated. However, the velocity was not high enough to sustain PAC in solution due to the large pipe diameter. A velocity of at least 3.5-5ft/s is desired to keep PAC suspended and only 1 ft/s was available.

37 Major Unit Process Evaluation - City of Wilmington Water Treatment Plant Microcystins Destruction at 50µg/L of Extracellular Microcystin Microcystin Oxidation at ph 8.6 (A) 4.52 Microcystin Oxidation at ph 8.6 with safety factor of 2 (B) 2.26 Peak Instantaneous Flow MGD Microcystin Oxidation at ph 9.0 (C) 2.92 Microcystin Oxidation at ph 9.0 with safety factor of 2 (D) (A) In this option, a ph of 8.6 is considered due to its more effective oxidation of microcystin. There may be implications regarding lead and copper at this ph level and Ohio EPA would need to be consulted prior to implementation. A corrosion control study may also need to be conducted for the system. (B) This option applies a safety factor of 2 to A. (C) Current conditions at the plant. (D) This option applies a safety factor of 2 to C. Note: These options consider a worst case scenario of an initial extracellular microcystin concentration of 50 µg/l entering the clearwell with a reduction to 0.3 µg/l.

38 Case Study #3 Lessons-Learned Performance-limiting factors identified were not necessarily tied to HABs and have a more continuous impact on plant operations Difficulty in Estimating PAC Capacity Jar testing helps yield real world results for the MUP evaluation Chemical additions along side PAC addition greatly impact effectiveness Further studies are needed at the EPA research lab Microcystin Oxidation Further studies regarding chlorine residuals and disinfection may be need

39 Questions? For More Information: Ryan Bertani (HAB Engineer) (614)