Mary Portillo, MWH WateReuse Texas

Transcription

1 Mary Portillo, MWH 2015 WateReuse Texas

2 Background Reverse osmosis (RO) will play an integral role in treatment of water for direct potable reuse. However, credit for microbial removal while employing RO is limited. There are no integrity monitoring methods for RO systems employed at the full-scale that directly demonstrate microorganism removal. Several integrity testing methods have been evaluated for NF and RO membranes but with limitations. It is important to develop a method that is not only practical but is also cost effective. 2

3 Direct Potable Reuse (DPR) Treatment Goals Rule (CDPH): 12 log enteric virus, 10 log Giardia, 10 log Cryptosporidium. Log Credits Cryptosporidium Giardia Virus Virus Goal Secondary Treatment UF RO UV+H 2 O Chlorine/Engineered Storage Total

4 Project Approach Task 1 Conduct comprehensive literature review to document NF/RO integrity methods. Task 2 Conduct workshop to define best approaches towards integrity monitoring of NF and RO membranes. Task 3 Task 4 Identify indicative parameters in different source waters to yield at least a 4 log removal of microorganisms. Bench-Scale Study: Develop a protocol for integrity monitoring, perform benchscale studies to assess failure modes and innovative techniques, perform a cost analysis for method developed. Task 5 Pilot-Scale Testing: Perform pilot-scale testing to capture long-term operational data under a variety of environmental conditions. 4

5 Participating Water Utilities Participating Utility Plant Type Workshop Participation Role in the project Water Quality, Operational Data Water Samples for Bench/Pilot Testing Bench/ Pilot Testing Site (Potential Sites) OCWD, California Full-scale IPR X X X X West Basin, California Full-scale IPR; Demoscale seawater X X X San Diego, California Demo-scale IPR X X El Paso, Texas Full-scale brackish groundwater X X Tampa Bay, Florida Full-scale seawater X X Coliban Water, Australia Full-scale UF+RO X X X X Veolia Water, Western Corridor, Australia Full-scale IPR X X United Water Several NF/RO plants X X PUB Singapore Full-scale IPR X X 5

6 Literature Review 6

7 NF/RO Integrity Monitoring Methods Important to detect membrane failure and breaches. Several established methods are available for integrity monitoring. Type Examples Advantages and Limitations Direct integrity testing Indirect integrity testing Challenge testing Pressure hold Vacuum decay Conductivity monitoring Sulfate monitoring TOC monitoring Microbial or nonmicrobial surrogate testing Sensitive but frequency dependent; performed offline; elements must be removed. Insensitive or expensive depending on capabilities of instrumentation. Most appropriate for pathogen reduction;offline analysis; can be costly. 7

8 Log Reduction Value (LRV) Log Reduction Value (LRV) the key outcome of a challenge test LRV = log 10 (C f /C p ) C f = feed concentration of challenge species C p = amount detected in permeate Typical LRVs for pathogen removal by RO (various methods): Viruses Bacteria Protozoa References Madireddi et al >5.9 <4.8 Gagliardo et al. 1997a; Gagliardo et al. 1997b > >5.7 Adham et al. 1998a 2.7->6.5 Adham et al. 1998b Kruithof et al Lozier et al Mi et al Casani et al > >5.3 >4.7->5.4 Kumar et al avg

9 Challenge Testing Results Microorganism/ Surrogate Virus (MS2 bacteriophage) Log Removal Value 1.4 to > 7.4 (Adham et al., 1998) RO 2.1 to > 5.9 (MWH, 1997; MWH 2006) RO 5.4 to 6 (Mi et al., 2004); > 7 (Lozier and Marinas, 2003) RO 5.4 to 6.8 (Lovinset al., 2002) NF 3 to 5.5 (Lozier and Marinas, 2003) NF Giardia > 4.8 (MWH, 1997) RO Cryptosporidium > 4.7 (MWH, 1997) RO Pseudomonas aeruginosa 2.9 (average)(usbr, 2000) RO E. coli 4.39 to > 5.3 (Spangenberg, 2003) RO Membrane Type 9

10 Challenge Testing Results Non biological surrogates Log Removal Value Membrane Type (VU, 2011) RO Fluorescent microspheres 4 (Lozier and Marinas, 2003) RO 2.5 to 4 (Lozier and Marinas, 2003) NF (VU, 2012) RO Dye (Rhodamine WT) 4 (Lozier and Marinas, 2003) RO 2.5 to 4 (Lozier and Marinas, 2003) NF Dye (Methyl violet) Dye caused membrane fouling (Spangenberg, 2003) RO Dye (FD&C 40) 3 (USBR, 2000) RO 2.7 to 4 (MWH, 2006) RO TRASAR 2 log injected with antiscalant (MWH, 2006) RO > 6 log injected as neat chemical (MWH, 2006) RO 10

11 Challenge Testing Establish a LRV of a challenge species. Challenge species should be easily rejected by the system. Several integrity testing methods have been evaluatedfor NF and RO membranes but with limitations. It is important to develop a method that is not only practicalbut is also cost effective. 11

12 Direct Integrity Monitoring Pressure-based tests: vacuum, pressure decay Primarily a screening test Vacuum (inches of Hg) Membrane A Membrane B Intact element Defective element Time (min) 12

13 Indirect Integrity Monitoring Particle monitoring limited to relatively large particles (0.5 micron). Turbidity monitoring low sensitivity. Sulfate monitoring online systems expensive. Conductivity monitoring low resolution, probing more effective. TOC monitoring similar capability as conductivity. Periodic testing combination of other tests, higher sensitivity. 13

14 New and Emerging Methods/Techniques 14

15 Rhodamine WT (RWT) RWT C 29 H 29 N 2 NaO 5 ; Da; 2.01 nm hydrodynamic diameter Non toxic Commercially available Insensitive to UV light Feed Concentration LRV Reference(s) (type*) mg/l (C) (Kitis et al. 2003a) 1-2 mg/l (C) 3.9 (Kitis et al. 2003b) 1 mg/l (C) (Lozier et al. 2003) mg/l (C) 2-5 (Lozier et al. 2013) 0.1 mg/l (C) 2.6 (Lozier et al. 2011) 5-10 mg/l (P) >4 (Ostarcevicet al. 2013) Source: UCLA, WRRF-09-06b *type: C = continuous, P = pulse 15

16 Pulsed Integrity Tests Pulse Integrity Test (PIT) oinjection of short pulse of highly rejected challenge species MgSO 4 (12,700 mg/l) injected at low pressure (15.5 bar) to identify construction defects. PIT profiles can be correlated to failure modes. o Pulsed Marker Membrane Integrity Monitoring (PM-MIMo) System. PM-MIMo Source: WRRF-09-06b Real time monitoring for RO systems. Pulsed dosing of fluorescent marked in RO feed stream. Spectroflurometer system to monitor marker in permeate stream. 16

17 TRASAR Testing 610 Da Fluorescent Macromolecule Log Removal Values (LRV) Stage 1 Stage 2 0 Conductivity Sulfate TRASAR MS2 Bacteriophage MWH, 2006 Stage 1 - Intact Membranes 8.0 Stage 1 -With cut O-Rings Log Removal Values (LRV) Conductivity Sulfate TRASAR MS2 Bacteriophage MWH,

18 Multi-parameter Optical Detection Tryptophan E.Coli Analyte Lower Detection Limit TOC 0.1 mg/l BOD 2.0 mg/l Nitrate + Nitrite 0.01 mg/l E. coli 2 CFU/100 ml NOM 0.1 mg/l Combination of absorbance, fluorescence and reflectance. Tryptophan used as biomarker for detection of pathogens. Tryptophan detected by fluorescence in the ultraviolet frequency range. 18

19 On-line COD Photocatalystelectrodes used to generate high oxidation potential. Measurement of photo-current generated by oxidation of organics. 0.2 mg/l ± 3% sensitivity. Can differentiate 1 st and 2 nd pass RO permeate. Need reagents. TDS (mg/l) COD (ppm) 1 st pass permeate nd pass permeate

20 Dynamic Light Scattering (DLS) Brownian motion of particles causes scattering of laser light. Size range: 0.6 6,000 nm; MW < 1,000 Da. Can handle continuous flow with low volume requirement 2 microl. DLS correlated with viral counts (WRRF-09-06a). No reagents required. High capital cost but low maintenance. Source: 20

21 Emission Excitation Matrices (EEMs) RO Feed RO Permeate 1 st Pass Water Recycling Plant, Victoria, 2013 EEM is used for organic matter finger printing. EEM combined with size exclusion chromatography (SEM) can be used for NF/RO integrity (Pype et al., J. Membr. Sci., 2012). EEM more sensitive than conductivity measurements with quantification of DOM rejection > 99.9% (Pypeet al., J. Membr. Sci., 2012). 21

22 On-line Pathogen Detection Emerging Techniques Quantum Dots (QDs) Fiber Optic Biosensors Electrochemical Biosensors Resonance Biosensor Whispering Gallery Microlasers Nanocrystalsof semiconducting material that have tunable properties, biocompatible, highly flurorescent, easy to synthesize and can be formed in a range of sizes (20 30 nm). Laser derived evanescent wave is excited over sample and fluorescence measured. Immobilization of antibodies onto biofunctionalized electrodes (gold). Visible or near IR radiation via a hemispherical prism. Electromagnetic waves generated and detected. Label-free detection of single viral pathogens using evanescent wave (acoustic) sensor. 22

23 Criteria for Ideal Integrity Monitoring System Category Criteria Requirement(s) Capital cost Reasonablecapital investment. The ability to be fully integrated into Installation/integration Capital & existing systems as well as new systems. Equipment Should require minimal training for Operation operators. Technique Operation costs Reasonableoperation costs. Test type Test should be real-time and online. Sensitivity High sensitivity at low challenge species concentration. Selectivity Challenge species should be representative of pathogens of concern. Output Test should deliver minimum LRV of 4. 23

24 Questionnaire Responses 24

25 Survey Questionnaire 25

26 Membrane Manufacturers 26

27 Membrane Manufacturers Cause of Integrity Breach Manufacturer A B C Damaged O-rings X X X Glue line leaks X X X Oxidant Damage X X Permeate Back Pressure X System/piping leaks X X Exceeding operating conditions X Damage due to particulates/foulants X X X Preservative damage Major breaches caused by damaged O-rings, glue line leaks and particulate damage. Number of questionnaires sent out 4 Number of responses received 3 27

28 Membrane Manufacturers Autopsy Testing Manufacturer A B C Dye uptake X X X Single element wet test X X Scanning Electron Microscopy (SEM) X X Flat-sheet testing X X X Vacuum decay test X Electron Spectroscopy Chemical Analysis (ESCA) X Wide range of tests used to autopsy failed elements. Dye uptake and performance testing of coupons most common. 28

29 Membrane Manufacturers Integrity Testing (post-manufacturing) Manufacturer Test A B C Vacuum decay test X X Pressure decay test X X Wet element test X X Manufacturers surveyed use 1-2 post-manufacturing integrity tests. Mainly for identifying defects, not for pathogen integrity. 29

30 Water Utilities 30

31 Water Utilities Water Utility Feed Water Type A B C D E Wastewater X X X X Groundwater X Majority of feed water sourced from wastewater. Potential for high microbial contamination. End Use of Treated Water Drinking Water Groundwater Replenishment Indirect Potable Reuse Industrial/other Reuse Water Utility A B C D E X X X X X X Variety of uses of product water. Majority for industrial or other reuse. Number of questionnaires sent out 9 Number of responses received to date 5 31

32 Water Utilities Permeate Monitoring Water Utility Technique A B C D E Turbidity X X Total Organic Carbon (TOC) X X Conductivity X X X X X Sulfate Particle Counting UV254 X X Several monitoring tests employed Conductivity the most common. Overview of plant performance, not necessarily for membrane integrity. Challenge Test at Fullscale Water Utility A B C D E Conductivity probing X Rhodamine WT MS2 virus X None X X X Most utilities do not perform membrane integrity challenge tests at full-scale. Test not undertaken as no microbial credits claimed. 32

33 Water Utilities Cause of Integrity Water Utility Breach A B C D E Exceeding operating conditions X Damaged o-rings X X Damage due to particulates/foulants X System/piping leaks None X X Damaged O-rings common cause of integrity breaches. Some utilities also reported no membrane integrity breaches. 33

34 Water Utilities Lessons Learned Some water utilities reported no integrity breaches. Damaged, degraded and rolled O-rings were the major cause of integrity breach. Some water utilities reported MS2-phage virus testing. Others report no challenge testing is performed. Online monitoring of combined permeate can be misleading. Conductivity should be performed on individual stages periodically. 34

35 Water Utilities Lessons Learned Fouling/scaling can also present higher conductivity which resolves after chemical cleaning. Online TOC has lower sensitivity than lab-scale instruments and not as reliable as conductivity, UVT. Issues can arise from online TOC due to maintenance, calibration and consumables/reagent packs. 35

36 On-line Monitoring Technology Providers 36

37 TRASAR System requirements: 100 ml/min; C; 10 psi; Calibration required. Costs: $20,000 (capital), $5,000 (O&M). Pilot-scale/full-scale Testing: Evaluated at pilot-scale. Requires injection as a neat chemical without antiscalant tagging to achieve high LRVs (> 6). Number of questionnaires sent out 2 Number of responses received 2 37

38 ZAPS System requirements: 2 ml/min (minimum); C (maximum); 60 psi (maximum); 115 VAC, 1000 Watts. Maintenance: Real-time data collection. Maintenance requirements include manual cleaning to prevent biofilm growth. Cleaning rate varies from once/year to once/week. Fully automated functionality. Costs: Costs: $65,000 (capital), $100 (O&M). No requirement for chemicals, reagents or consumable supplies. Pilot-scale/full-scale Testing: Evaluated at pilot-scale. More frequent manual cleaning required depending on water quality. Continuous sample flow required. 38

39 Potential Methodology for Integrity Testing

40 Summary Integrity monitoring of NF/RO systems is important for recycled water systems where real membrane rejection is often not realized due to lack of accurate, reliable, real time and cost effective online testing. Several techniques are available for NF/RO integrity monitoring. Selection of the best technique and methodology will depend on the speed, accuracy and cost competiveness compared to available monitoring techniques. 40

41 Acknowledgements Coauthors: Joe Jacanglo(MWH), ArunSubramanian (Chesapeake Energy), Marlene Cran(Victoria University), Stephen Gray (Victoria University) Funding: WateReuse Research Foundation (Project #WRRF-12-07). Project Manager: Kristen Cwalina(WateReuse Research Foundation). Project Advisory Committee (PAC) Members: Dr. Robert Cheng (MWD), Mr. Harry Seah(PUB-Singapore), Mr. Wang Honglei(PUB- Singapore), Dr. Mark Wilf, Dr. Erik Roesink(Pentair). Membrane Manufacturers: DowFilmtec, Toray, NanoH 2 O, CSM Woongjin. Water Utilities: OCWD, West Basin, City of San Diego, El Paso, Tampa Bay, ColibanWater (Australia), PUB Singapore, Veolia Water, United Water. Johns Hopkins University: Jason Bashai 5, Kellogg Schwab 5 Victoria University: Marlene Cran, Stephen Gray 41