1 / 17

Tracer Study Best Practices: Avoiding Common Mistakes

Learn about proper tracer study procedures to assist utilities in testing water systems accurately and efficiently. Discover key issues, tracer selection, sample frequency, run length, mass recovery, and more to ensure successful results. Avoid common mistakes and optimize your tracer tests with expert advice.

pattywatson
Download Presentation

Tracer Study Best Practices: Avoiding Common Mistakes

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. 2002 CA-NV-AWWA ANNUAL FALL CONFERENCEOCTOBER 17, 2002Tracer Studies Common Problems & Mistakes Presented by: Guy Schott, P.E. Associate Sanitary Engineer CA DHS-Drinking Water Program 707-576-2732 gschott@dhs.ca.gov

  2. Information to get out of Presentation • Assist utilities in determining if a tracer study was conducted properly. • Present information that can help utilities and consultants to avoid conducting a poor tracer test.

  3. Issues • Tracer Selection • Sample Frequency • Run Length • Tracer Mass Recovery • t10 Calculations for Reactors in Series • Chemical Feed Pump (Step-Dose)

  4. Tracer Selection Most common tracers: • Fluoride (low analytical cost) • Lithium (high analytical cost), requires very little tracer mass in tracer test. Others • NaCl • Rhodamine WT • Calcium • Zinc Tracer should be non-reactive

  5. Appropriate Tracer Selection Consider tracer reaction, quantity & analytical cost Example: 10 lbs of Lithium Chloride vs. 2,000 lbs of NaCl Density current may result with NaCl & not practical to dose large quantity; use Lithium Mistakes Seen: • Fluoride tracer used in sedimentation Problem: fluoride reacts with alum. • Consider lithium

  6. Sample Frequency Must have adequate number of samples to define mass recovery curve. Mistakes Seen: Save money on sample analysis, thus take less samples – Results In: Inadequate samples and poor results – test run invalidated.

  7. Example – Lack of Samples Deficient samples, Unaccounted tracer mass lost

  8. Example – Lack of Samples Deficient samples, Unaccounted tracer mass gain

  9. Test Run Length • Ideally, 3 to 4 theoretical detention times (T) • Less may be adequate if situation calls for it. Mistakes Seen: Inadequate test runs (.4T to 1.5 T) Results In: inadequate tracer mass recovery - test run invalided.

  10. Goal: high mass recovery (90 – 100 %) 80% - 90% (fair to good recovery) Verify mass recovery: Mistakes Seen: Incorrectly calculated mass dosed. Use wrong molecular weight. Results In: Improved or poor mass recovery. Tracer Mass Recovery & Calculated Error

  11. Two tanks in series: Check Results (does it make sense): real example of short test run and mass recovery Tracer Tank 1 Tank 2 Sample pt. 1 Sample pt. 2 96% recovery 0.8T run time (Tanks 1 & 2) Does this make sense? Check run time and mass recovery calculations

  12. Two tanks in series: Check Results (does it make sense): example of short test run and mass recovery Tracer Tank 1 Tank 2 Sample pt. 1 168% recovery, 1.5T run Time (Tank 1) Sample pt. 2 96% recovery, 0.8T run Time (Tanks 1 & 2)

  13. Two tanks in series: T10 Calculations for Reactors in Series Tracer Tank 1 Tank 2 Sample pt. 1 t10 = 10 minutes Sample pt. 2 t10 = 53 minutes (overall) Wrong: 53 min. – 10 min = 43 min (t10 for Tank 2 alone) This method cannot be used to determine t10 for Tank 2 alone.

  14. Chemical Feed Pump (Step-Dose) • Select reliable chemical feed pump for tracer test. (Problem Seen: Erratic feed pump – results in poor tracer test) • Throughout test, analyze samples down stream of feed pump before reactor to verify tracer dosage. • High tracer dosages will overcome any minor variations in chemical feed pump.

  15. Develop Tracer Protocol • A well developed test protocol can result in a successful test. • Submit to DHS for review and comments.

  16. Reference • Tracer Studies in Water Treatment Facilities: A Protocol and Case Studies American Water Works Association Research Foundation ISBN 0-89867-857-9

  17. Tracer Study Data Base To receive copy of California’s tracer data base, send email to: Guy Schott gschott@dhs.ca.gov Summarizes results of tracer test and respective tank configurations.

More Related