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The BOD Test from A – Z (aka A Bug’s-Eye-View of the BOD Test )

The BOD Test from A – Z (aka A Bug’s-Eye-View of the BOD Test ). Perry Brake Lab Testing Consultant (253) 565-5350 pudljumper1@comcast.net Presented at OELA Workshop, 5/24/12. Powerpoint presentation posted at www.perrybrake.com/BODSolutions.html. References. Specifically, Method 5210B

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The BOD Test from A – Z (aka A Bug’s-Eye-View of the BOD Test )

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  1. The BOD Test from A – Z(aka A Bug’s-Eye-View of the BOD Test) Perry Brake Lab Testing Consultant (253) 565-5350 pudljumper1@comcast.net Presented at OELA Workshop, 5/24/12 Powerpoint presentation posted at www.perrybrake.com/BODSolutions.html

  2. References • Specifically, Method 5210B • in 18th,19th, 20th, or On-Line * Editions. • 22d Ed. is out, but not yet approved • Also... • EPA Method 405.1 • USGS Method I-1578 • AOAC Method 973-44*

  3. What is in that BOD Bottle? Bacteria Oxygen Organic Material Nitrogen-containing Organic material Nitrifying Bacteria Nitrogen (ammonia, ammonium, nitrites) BOD O2 BOD O2 O2 O2 BOD N O2 N BOD O2 O2 N Plus water, nutrients, buffers, inert material, sometimes interferents

  4. What’s happening inside that BOD Bottle? • CxHyOz O2 CO2 + H20 O2 CO2 + H20 + NH4+ • CxHyOzN O2 BOD - NO3 Examples: C6H12O6– Glucose C4H7O4N – Glutamic Acid

  5. What’s happening inside that BOD Bottle? • CxHyOz O2 CO2 + H20 O2 CO2 + H20 + NH4+ • CxHyOzN O2 Inhibitor CBOD - NO3 Examples: C6H12O6– Glucose C4H7O4N – Glutamic Acid

  6. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  7. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  8. Sampling • Type – Grab or Composite • Volume _____________ * BOD ranges fromEPA’s Operation of Wastewater Treatment Plants, vol. II, 3rd Ed., 1991.

  9. Sampling • Type – Grab or Composite • Volume _____________ * BOD ranges fromEPA’s Operation of Wastewater Treatment Plants, vol. II, 3rd Ed., 1991.

  10. Sampling • Type – Grab or Composite • Volume • Maximum Volume/bottle - ~295 mL (sample, seed, special nutrient/buffer “pillow”, top off with H2O)

  11. Sampling • Type– Grab or Composite • Volume • Minimum Volume/bottle – none, but dilute entire sample for extremely high BOD samples

  12. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  13. Sample Preservation/Holding Time • Preserve at 4°C* if sample cannot be set up in 2 hrs • Holding time: Analyze as soon as possible... • But not to exceed 48 hours (40 CFR 136) • But not to exceed 24 hours (Standard Methods) • But not to exceed 6 hours (some states) • Holding time begins at end of composite • Waiver - permit managers can waive 48-hour requirement __________ * 21st Edition of SM (and latest 40 CFR 136) says < 6°C but above freezing (unless study shows no difference if frozen)

  14. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  15. Equipment • DO measurement • Meter (plus barometer if meter has none) • Winkler setup • LDO meter (EPA approved, but Regions require ATP study except Region 6) • Dilution water container(s)w/siphon or gravity flow; glass best, but Nalgene® OK • Thermometer(s) – 1° increment, traceable to NIST • Incubator/Water Bath – no light, 20±1° C, circulation • BOD Bottles – glass most common; Env’l Express plastic OK; 60-, 75- 250-, 300-mL available...300-mL by far most common

  16. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  17. Reagents • Buffers/Nutrients • Can prepare from reagent-grade chemicals, or purchase “pillows” • Special “pillow” for 300-mL bottle • Standard* (GGA) • Can prepare from chemicals, or... • Purchase ready made • Hach GGA standard is 300 mg/L each G and GA • North Central Labs std is 150 mg/L each G and GA • KHP can backup, but not replace, GGA ________ • Standard – solution of known concentration, or expected value in the case of the BOD test

  18. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  19. Sample Pretreatment • Sample prep • Well-mixed sample critical • Pre-dilute high-BOD samples • Temperature • 20 ± 1°C before reading initial DO (18th, 19th, 20th) • 20 ± 1°C before dilution (21st edition of SM) • pH – if <6.0 or >8.5, adjust to 7.0 – 7.2 • Dechlorination – w/sodium sulfite, but might outgas naturally

  20. Sampling • Type– Grab or Composite • Volume • Minimum Volume/bottle – none, but dilute entire sample for extremely high BOD samples

  21. Sample Pretreatment • Sample prep • Well mixed sample critical • Pre-dilute for high-BOD samples • Sample Temperature • 20 ± 1°C before reading initial DO (18th, 19th, 20th) • 20 ± 1°C before dilution (21st edition of SM) • pH – if <6.0 or >8.5, adjust to 6.5 – 7.5 • Dechlorination – w/sodium sulfite, but might outgas naturally

  22. Sample Pretreatment (cont’d) Other toxic substances – metals, septage Toxicity will result in higher BOD for increasing dilution in series of bottles ---> Supersaturation – often a problem in winter; can be avoided by vigorous shaking of sample, allowing to sit for at least one hour Nitrification inhibition - Add pyridine inhibitor to samples, seed control, GGA, but NOT to blank

  23. Convincing Evidence of Toxicity

  24. Sample Pretreatment (cont’d) • Other toxic substances – metals, septage • Toxicity will result in higher BOD for increasing dilution in series of bottles • Supersaturation – often a problem in winter; can be avoided by vigorous shaking of sample, allowing to sit for at least one hour • Nitrification inhibition - Add pyridine inhibitor to samples, seed control, GGA, but NOT to blank

  25. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  26. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  27. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  28. Preparation of Dilution Water • Source water is critical • Distilled often contains Cl2, NH3, organics • DI often contains organics • Bad blanks? Try “steam distilled” water • Dilution water for BOD • Aerate, store at 20°, add buffers/nutrients morning of test, settle for one hour (CBOD dilution water can be stored) • Check pH, do blank • Do not add inhibitor to blank

  29. “Steam Distilled” Water

  30. Preparation of Dilution Water • Source water is critical • Distilled often contains Cl2, NH3, organics • DI often contains organics • Bad blanks? Try “steam distilled” water • Dilution water for BOD • Aerate, store at 20°, add buffers/nutrients morning of test, settle for one hour (CBOD dilution water can be stored) • Check pH, do blank • (do not add inhibitor to blank)

  31. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  32. Estimating BOD • Establish correlation with TSS • Do a COD (BOD usually 60-70% of COD) • In PT studies, BOD/COD = ~0.63, BOD/TOC = ~1.58, BOD/CBOD = ~1.16

  33. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  34. Seeding • Always seed unless known to be unnecessary • Source of seed (need good source of bacteria) • Domestic WWTP – 1° effluent; 2° effluent; influent (often variable) • Industrial WWTP or Private Lab – Synthetic seed • Polyseed® - no nitrifiers • Biosystems® - has nitrifiers (or does it??) • Seed Check • Seed control – should deplete 0.6 – 1.0 mg/L per mL of seed • Glucose/Glutamic Acid – true test of seed • Goal is: average ~198 mg/L; standard deviation <<30.5 mg/L • KHP – OK as supplement

  35. KHP Standard (300 mg/L) ParameterExpected Value BOD 249 mg/L COD 343 mg/L TOC 141 mg/L pH 4.4 pH units Total Solids 300 mg/L Volatile Solids 169 mg/L Conductivity 169 mhos Acidity 74 mg/L _________ Source: WA Dept of Ecology Manchester Laboratory (lab attained a standard deviation for BOD of 15 mg/L…very precise work)

  36. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  37. Dilution of Sample • Bottle Method • Add sample, seed, dilution water to bottle • Never add seed to empty bottle • Add inhibitor only after sample/dilution water • Graduated Cylinder Method • Add sample, seed, dilution water to grad cylinder • Dilution Series • Do enough dilutions to assure at least one has depletion of >2 mg/L, retention of >1 mg/L • Remember – if more than 200 mL of sample is in bottle, use special buffer/nutrient packets

  38. Typical Dilution Series • Blank – 1 bottle • Seed control – 1 or 2 bottles, same dilution • Don’t forget...must deplete at least 2 mg/L • G/GA – 1 bottle, ~6 mL, OK...some labs do 2 • Effluent – 1 bottle OK if precision is good* • Seed must contribute 0.6 – 1.0 mg/L depletion • Influent – 3 dilutions minimum recommended • Unknown – 3 dilutions minimum, 5 better _________ * Some states do not allow only one

  39. Typical Dilution Series • Standard Methods staff published a memo (May 19, 2009) saying they never intended to require more than one dilution for any given BOD sample. • Check www.perrybrake.com/BODSolutions.html for a copy of the memo

  40. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  41. Determination of Initial DO • Winkler great...but time consuming • DO meter • Proper calibration critical • Refer to DO chart to see if reading is reasonable • Do all measurements at 20 ± 1° C • Use actual barometric pressure • If using air calibration, use 100% saturation • LDO meter simplifies procedure

  42. DO Saturation vs. Temp/Pressure PressureTemperature (°C) (inches Hg) 17.0 18.0 19.0 20.0 21.0 22.0 23.0 26.6 8.61 8.42 8.25 8.07 7.91 7.75 7.59 26.8 8.67 8.48 8.31 8.13 7.97 7.81 7.65 27.0 8.73 8.54 8.37 8.19 8.03 7.87 7.71 - - - - - - - - 31.1 10.1 9.84 9.64 9.45 9.27 9.09 8.92 31.3 10.1 9.90 9.70 9.51 9.33 9.15 8.97

  43. Determination of Initial DO • Winkler great...but time consuming • DO meter • Proper calibration critical • Refer to DO chart to see if reading is reasonable • Keep all measurements at 20 ± 1° C • Use actual barometric pressure • If using air calibration, use 100% saturation • LDO meter simplifies procedure

  44. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  45. Incubation • Water seal plus cap (unless water bath used) • At 20 ± 1° C (NIST-traceable thermometer • In dark • Circulating air/water • For 5 days, ± 2 hours (21st Ed. says ± 6 hours) • All bottles done together, same incubator (i.e., in same “batch”)

  46. Analytical Procedure • Preparation of Dilution Water • Estimating BOD • Seeding • Dilution of Sample • Determination of Initial DO • Incubation • Determination of Final DO

  47. Determination of Final DO Same process as for initial DO

  48. What References Say (and Don’t Say) About... • Sampling • Sample preservation/holding time • Equipment • Reagents • Sample Pretreatment • The Analytical Procedure • Calculations/Data Recording • QA/QC and Performance Monitoring

  49. Calculations/Data Recording • Dilution Factor • BOD – Seeded • BOD – Not Seeded • Benchsheet • Reporting Results

  50. Benchsheet Must include: • Date/time sample taken, set up, final reading • ID of sampler and analyst • ID of sample • Sample pH • Sample temp when initial DO reading taken • Bottle numbers • Volume of seed in each bottle or graduated cylinder • Volume of sample in each bottle or graduated cylinder • Initial and final DO for each bottle • Space for calculation of “f”, “DF” • Final BOD result • Space for reviewer to initial • Space for comments

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