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Cyanide Attenuation Study

Use of Trace-Level Cyanide Method to Determine Attenuation of Discharged Cyanide in Lower South San Francisco Bay. Cyanide Attenuation Study. Paradox.

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Cyanide Attenuation Study

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  1. Use of Trace-Level Cyanide Method to Determine Attenuation of Discharged Cyanide in Lower South San Francisco Bay Cyanide Attenuation Study 2006 NWQMC Presentation

  2. Paradox …although the origins of terrestrial life appear to have been dependent in part on the presence and chemical reactivity of HCN and its derivatives, paradoxically it is toxic to the majority of living matter (Timothy C. Marrs and Bryan Ballantyne) 2006 NWQMC Presentation

  3. Regulatory Driver for Study • EPA Cyanide Criterion is 1.0 mg/L • Proposed S. F. Bay SSO is 2.9 mg/L • Most Shallow-Water Dischargers cannot meet this limit 2006 NWQMC Presentation

  4. Compliance Strategies • Water-Effect Ratio study: results  1 • Spiking study • Translator Study • Free:Total cyanide • EPA criteria based on free cyanide • MDL for free cyanide too high • Fate and transport study • Need trace total cyanide method 2006 NWQMC Presentation

  5. Attenuation Study • F & T Most Reasonable Strategy for Relief • Attenuation = dilution + degradation • Based on low levels of Total Cyanide • Need Lower Reporting Limit • Another type of “Translator” 2006 NWQMC Presentation

  6. Trace Cyanide Method Development • MDL for conventional method : 1-2 mg/L • Proposed SSO requires MDL of < 0.5 mg/L • Trace method adapted from Standard Methods, 18th edition- 4500 CN-B,C &E 2006 NWQMC Presentation

  7. Method Modifications • Concentration Factor increased from two to six fold • Increased distillation time • Use of a 10 cm Cell for color determination • Use of Nitrogen as a carrier gas 2006 NWQMC Presentation

  8. Methodology • Preliminary Treatment of samples • to remove interferences • Distillation • to liberate cyanide as gaseous HCN from the matrix background. HCN is collected as CN- in the NaOH scrubbing solution • Colorimetric Determination of Cyanide • UV-VIS Spectrophotometer 2006 NWQMC Presentation

  9. Distillation Apparatus • Heating Mantles • Distillation Flasks • Cold Finger Condenser • Sparger • Sparger Vessel • Nitrogen Gas 2006 NWQMC Presentation

  10. Distillation Procedure • Sample Volume: 700 ml • Reagents: 70 ml 0.04N NaOH PbCO3 MgCL2, NH2SO3H H2SO4 Spikes: 2-5ug/L (1ug/ml std) KCN Nitrogen Flow Rate 2-4 air bubbles/sec 2006 NWQMC Presentation

  11. MDL Studies 2006 NWQMC Presentation

  12. Cyanide Recoveries 2006 NWQMC Presentation

  13. Holding Time Experiments 2006 NWQMC Presentation

  14. Effect of NaOH Preservation 2006 NWQMC Presentation

  15. Cyanide Recoveries in Raw Sewage 2006 NWQMC Presentation

  16. Cyanide Recoveries in Raw Sewage • Recoveries : Independent of Spike Concentration Higher with K3Fe(CN)6 than KCN • Average Recoveries with K3Fe(CN)6: - 74.2% Preserved - 83.5% Unpreserved 2006 NWQMC Presentation

  17. Future Research • Cyanide Speciation Studies – Free Cyanide • Sample Preservation Issues • Cyanide Formation: - Chloramination - Thiocyanate 2006 NWQMC Presentation

  18. Plant Cyanide Measurements 2006 NWQMC Presentation

  19. Plant Variability Study 2006 NWQMC Presentation

  20. Cyanide Sampling Stations Outfall 2006 NWQMC Presentation

  21. 2006 NWQMC Presentation

  22. 2006 NWQMC Presentation

  23. 2006 NWQMC Presentation

  24. Cyanide Attenuation 2006 NWQMC Presentation

  25. Cyanide Attenuation Factors 2006 NWQMC Presentation

  26. Cyanide Incident 2006 NWQMC Presentation

  27. Cyanide Attenuation Study Watershed Investigations and Laboratory Staff Watershed Protection Group Environmental Services Department City of San Jose September 1, 2004 Report available at: http://www.sanjoseca.gov/esd/pub_res.htm 2006 NWQMC Presentation

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