A novel saltwater AOC assay for optimizing desalination R/O-pretreatment Lauren Weinrich, Orren Schneider, Eugenio Giraldo...
Membrane fouling <ul><li>Major concern  </li></ul><ul><li>Impact on plant operation </li></ul><ul><li>Types of fouling </l...
Assimilable organic carbon (AOC) <ul><li>Total organic carbon (TOC) </li></ul><ul><li>Biodegradable fraction  </li></ul><u...
AOC application <ul><li>Test traditionally used in drinking water to evaluate biofouling potential and more recently in re...
AOC and desalination <ul><li>Very little is known about the biodegradable fractions of organic carbon in desalination plan...
Method development
Conventional AOC test <ul><li>Inoculate with pure strain </li></ul><ul><li>Monitor bacterial growth </li></ul><ul><li>Foll...
AOC: marine test organism <ul><li>Vibrio harveyi  </li></ul><ul><ul><li>ATCC® 700106 </li></ul></ul><ul><ul><li>Free-livin...
AOC:  V. harveyi  characterization <ul><li>Carbohydrate, Carboxylic acid, Amino acid, Alcohol, Aldehyde </li></ul>Note - g...
Reference carbon selection <ul><li>Identify linear relationships between luminescence and carbon concentrations </li></ul>...
Instrumentation  <ul><li>Luminometer – sensitive, automated,  photon-counting; 96-well microtiter  plate format that allow...
AOC Application and Results
Marine AOC procedure <ul><li>Carbon-free glassware. </li></ul><ul><li>Dechlorinate with sodium thiosulfate. </li></ul><ul>...
AOC: parallel analysis  Plate counts     Luminescence - Limited to single time point per day - Programmable - Culture peri...
AOC measurements: plate counts & luminescence <ul><li>n = 59; samples from jar tests, pilot and full scale desal plant </l...
Field testing - Moss Landing Pilot Plant <ul><li>Monterey Bay intake </li></ul><ul><li>TOC levels 0.9 – 1.9 mg/L </li></ul...
Field testing – full scale desalination facility <ul><li>Tampa Bay Seawater Desalination Plant </li></ul><ul><li>Collect s...
Tampa Bay desalination process schematic Precoat/Diatomaceous earth filters Junction box Seawater pump station Coagulation...
Field testing –Tampa AOC levels in November <ul><li>Error bars are deviations from 3 consecutive days of sampling </li></u...
Field testing – Tampa AOC levels in February <ul><li>Error bars are from duplicates </li></ul>
Rate of utilization  <ul><li>Monod kinetic growth modeling </li></ul><ul><li>Similar Nmax – substrate concentration </li><...
Field testing – Tampa rates of AOC utilization
Summary <ul><li>Vibrio harveyi  – bioluminescent marine organism </li></ul><ul><li>Similar methodology to AOC test </li></...
Summary cont’d <ul><li>Operational challenges for Tampa </li></ul><ul><ul><li>Fluctuations in water quality at intake  </l...
On-going work <ul><li>Further investigate cause of AOC removal through treatment </li></ul><ul><li>Look at variations in D...
Thank you! <ul><li>Water Research Foundation </li></ul><ul><li>American Water - Acciona Agua LLC </li></ul><ul><li>Tampa B...
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A Novel Saltwater AOC Assay for Optimizing Desalination R/O Pretreatment

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Presented at the May 24, 2010 14th Annual Water Reuse & Desalination Research Conference in Tampa Bay, FL. The title of the talk was "A Novel Saltwater AOC Assay for Optimizing Desalination R/O Pretreatment" and described a new way of measuring small organic carbon molecules in seawater that serve as food for bacterial growth. Growth of the bacteria on reverse osmosis membranes used to treat the seawater causes clogging problems and increases the energy required (and greenhouse gas emissions) and maintenance (more frequent cleaning).

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  • Constitutive luminescence rather then the high cell-density dependent bioluminescence
  • Constitutive luminescence rather then the high cell-density dependent bioluminescence
  • Cost ~$200 through ATCC
  • Measuring AOC was made convenient though the use of sensitive, automated, photon-counting luminometer. We can take fast measurements of the bacteria’s growth &amp; luminescence response in convenient 96-well microtiter plates, which greatly reduces labor associated with the original test. The traditional test monitored growth by plate counts and serial dilutions and proved to be too cumbersome for widespread application, particularly in utilities.. NEXT SLIDE
  • Lauria broth agar plates, 24 hours of growth at 30 deg C
  • Understand treatment train, location of sampling points and the impact of each individual treatment step
  • Testing desalination samples collected over 3 consecutive days at Tampa Bay for assimilable organic carbon (AOC). AOC levels were greatest before sand filtration indicating variability of the source water quality and most of the AOC removal occurred after the sand and diatomaceous earth filtration. Removal of this biodegradable fraction of carbon is important for protecting RO membranes from biofouling. TOC ranged from 4.9 – 5.4 ppm
  • TOC range 4.2 – 5.3 mg/L
  • Algal bloom, Alafia river dredging
  • Transcript of "A Novel Saltwater AOC Assay for Optimizing Desalination R/O Pretreatment"

    1. 1. A novel saltwater AOC assay for optimizing desalination R/O-pretreatment Lauren Weinrich, Orren Schneider, Eugenio Giraldo, and Mark LeChevallier
    2. 2. Membrane fouling <ul><li>Major concern </li></ul><ul><li>Impact on plant operation </li></ul><ul><li>Types of fouling </li></ul><ul><ul><li>Scaling </li></ul></ul><ul><ul><li>Pore blocking – particulates </li></ul></ul><ul><ul><li>Organic – NOM sorbs to the membrane surface </li></ul></ul><ul><ul><li>Biofouling – accumulation of biomass on a surface by growth and/or deposition </li></ul></ul><ul><li>Reduce fouling with pretreatment </li></ul><ul><ul><li>Coagulation </li></ul></ul><ul><ul><li>Optimized treatment of surface water </li></ul></ul><ul><ul><li>Lacking optimization tools in desalination pretreatment </li></ul></ul>
    3. 3. Assimilable organic carbon (AOC) <ul><li>Total organic carbon (TOC) </li></ul><ul><li>Biodegradable fraction </li></ul><ul><ul><li>Labile dissolved organic matter readily used by heterotrophic bacteria for growth </li></ul></ul><ul><li>Carbohydrates, carboxylic acids and other low molecular weight, highly polar, carbon compounds </li></ul><ul><li>Measured using a bioassay </li></ul>
    4. 4. AOC application <ul><li>Test traditionally used in drinking water to evaluate biofouling potential and more recently in reclaimed water to evaluate regrowth potential in the distribution system (WRF-05-002) </li></ul><ul><li>AW developed a test that uses bioluminescent strains of traditional test organisms NOX & P17 (Weinrich et al , 2009) </li></ul><ul><li>Automated test uses a sensitive, photon-counting, luminometer that allows high throughput, replicate analyses, at a low cost. </li></ul>
    5. 5. AOC and desalination <ul><li>Very little is known about the biodegradable fractions of organic carbon in desalination plants, particularly AOC. </li></ul><ul><li>Currently, no reliable method exists for measuring or removing AOC in water with high salinity such as seawater or brackish water. </li></ul><ul><li>Applications include R/O pretreatment testing for AOC removal, pilot and full scale desalination. </li></ul>
    6. 6. Method development
    7. 7. Conventional AOC test <ul><li>Inoculate with pure strain </li></ul><ul><li>Monitor bacterial growth </li></ul><ul><li>Follow parameter </li></ul><ul><ul><li>Plate counts – serial dilution of samples, spread plating on agar </li></ul></ul><ul><ul><li>Luminescence – natural or genetically modified light-producing bacteria </li></ul></ul><ul><li>Determine results - µg acetate carbon equivalents per liter </li></ul>Bacteria Nmax Time
    8. 8. AOC: marine test organism <ul><li>Vibrio harveyi </li></ul><ul><ul><li>ATCC® 700106 </li></ul></ul><ul><ul><li>Free-living bioluminescent bacterium </li></ul></ul><ul><ul><li>Constitutive expression of luminescence not being influenced by culture density </li></ul></ul><ul><ul><li>Characterize organism and determine carbon source </li></ul></ul><ul><ul><li>Test various low molecular weight carbon sources in 100 ug/L soln’s </li></ul></ul>
    9. 9. AOC: V. harveyi characterization <ul><li>Carbohydrate, Carboxylic acid, Amino acid, Alcohol, Aldehyde </li></ul>Note - glucose and acetate
    10. 10. Reference carbon selection <ul><li>Identify linear relationships between luminescence and carbon concentrations </li></ul><ul><li>Glucose limitations – catabolite repression </li></ul><ul><li>Acetate – standard for AOC testing </li></ul>
    11. 11. Instrumentation <ul><li>Luminometer – sensitive, automated, photon-counting; 96-well microtiter plate format that allows high throughput, replicate analyses, at a low cost. </li></ul><ul><li>Luminescence, in relative light units (RLU) defined as 10,000 times the integral of the (log photon count vs. time) curve for 30 second reaction times. </li></ul>
    12. 12. AOC Application and Results
    13. 13. Marine AOC procedure <ul><li>Carbon-free glassware. </li></ul><ul><li>Dechlorinate with sodium thiosulfate. </li></ul><ul><li>Pasteurize samples at 70 ° C for 30 minutes. </li></ul><ul><li>Inoculate with 10 4 cfu/mL V. harveyi stock (2 mg/L acetate C; 4 °C). </li></ul><ul><li>Transfer 300  L aliquots into 96-well microtiter plate. </li></ul><ul><li>Duplicate luminescence readings immediately, then monitored over time until peak luminescence (N max ) is reached. </li></ul><ul><li>*Determine growth kinetics ( µmax) </li></ul><ul><li>Convert luminescence to </li></ul><ul><li>AOC using std curves. </li></ul><ul><li>AOC Units - µg acetate </li></ul><ul><li>carbon equivalents per L. </li></ul>Bacteria Nmax Time
    14. 14. AOC: parallel analysis Plate counts Luminescence - Limited to single time point per day - Programmable - Culture period - Measured at hourly intervals - Labor - Better estimate of maximum http://www.sigmaaldrich.com/analytical-chromatography/microbiology/learning-center/theory/introduction.html
    15. 15. AOC measurements: plate counts & luminescence <ul><li>n = 59; samples from jar tests, pilot and full scale desal plant </li></ul><ul><li>r 2 = 0.91, p <0.01 </li></ul><ul><li>Plate count limitations overcome by measuring luminescence </li></ul>
    16. 16. Field testing - Moss Landing Pilot Plant <ul><li>Monterey Bay intake </li></ul><ul><li>TOC levels 0.9 – 1.9 mg/L </li></ul>2 0 1 4 34 September 1 7 23 13 11 October AVE June March 4 5 7 Cartridge filter 9 1 29 Ultrafilter 0.01 um 9 4 9 Ultrafilter 0.04 um 17 4 47 Self cleaning filter - 100 um pore size 17 7 Raw inlet
    17. 17. Field testing – full scale desalination facility <ul><li>Tampa Bay Seawater Desalination Plant </li></ul><ul><li>Collect samples from various pretreatment locations </li></ul><ul><li>Operational challenges </li></ul><ul><li>Determine baseline levels of organic carbon </li></ul><ul><ul><li>Pilot system (Monterey Bay) – TOC 0.9 – 1.9 mg/L </li></ul></ul><ul><ul><li>Full scale system (Tampa) – TOC 4.2 – 5.4 mg/L </li></ul></ul><ul><ul><li>AOC levels </li></ul></ul><ul><li>Evaluate organic removal through pretreatment </li></ul><ul><ul><li>Increase from disinfection </li></ul></ul><ul><ul><li>Filtration removes TOC and AOC </li></ul></ul>
    18. 18. Tampa Bay desalination process schematic Precoat/Diatomaceous earth filters Junction box Seawater pump station Coagulation basins Sand filters Chlorine dioxide Sulfuric acid Ferric Cartridge filters To RO Bisulfite Post- Pre- Post- Raw ClO 2 sand sand Post- Post- . Cart. DE
    19. 19. Field testing –Tampa AOC levels in November <ul><li>Error bars are deviations from 3 consecutive days of sampling </li></ul><ul><li>Issues with algal blooms and local river dredging </li></ul>
    20. 20. Field testing – Tampa AOC levels in February <ul><li>Error bars are from duplicates </li></ul>
    21. 21. Rate of utilization <ul><li>Monod kinetic growth modeling </li></ul><ul><li>Similar Nmax – substrate concentration </li></ul><ul><li>Different umax – rate of utilization </li></ul><ul><li>Compare umax in samples </li></ul>Bacteria Nmax Time
    22. 22. Field testing – Tampa rates of AOC utilization
    23. 23. Summary <ul><li>Vibrio harveyi – bioluminescent marine organism </li></ul><ul><li>Similar methodology to AOC test </li></ul><ul><li>V. harveyi is nutritionally versatile </li></ul><ul><li>Develop standard curves using acetate carbon </li></ul><ul><li>Luminescence measurements and modeling </li></ul><ul><li>Application - pilot and full scale R/O desalination </li></ul><ul><li>Understand how AOC affects seawater desal process </li></ul>
    24. 24. Summary cont’d <ul><li>Operational challenges for Tampa </li></ul><ul><ul><li>Fluctuations in water quality at intake </li></ul></ul><ul><ul><li>Periodic issues with fouling of DE filters </li></ul></ul><ul><ul><li>Disinfection increases AOC levels </li></ul></ul><ul><ul><li>Preliminary results indicate AOC removal in sand and diatomaceous earth filters </li></ul></ul>
    25. 25. On-going work <ul><li>Further investigate cause of AOC removal through treatment </li></ul><ul><li>Look at variations in DE lifecycles and related AOC removal </li></ul><ul><li>Expand sampling locations </li></ul><ul><li>Jar tests - Screen different coagulants for optimum conditions (Type, dose, pH, organic removal) </li></ul><ul><li>Comparison studies with freshwater AOC organisms P17/NOX </li></ul>
    26. 26. Thank you! <ul><li>Water Research Foundation </li></ul><ul><li>American Water - Acciona Agua LLC </li></ul><ul><li>Tampa Bay Water </li></ul><ul><li>California American Water </li></ul><ul><li>Contact Information </li></ul><ul><ul><li>Lauren Weinrich </li></ul></ul><ul><ul><li>[email_address] </li></ul></ul><ul><ul><li>Sr Research Analyst - Innovation and Environmental Stewardship </li></ul></ul><ul><ul><li>American Water </li></ul></ul><ul><ul><li>213 Carriage Lane </li></ul></ul><ul><ul><li>Delran, NJ 08075 </li></ul></ul><ul><ul><li>856-764-4922 office </li></ul></ul>

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