Calculation of Range of Dilutions forAcceptable BOD Results
Prepared ByMichigan Department of Environmental Quality
Operator Training and Certification Unit
BOD PROCEDUREBOD PROCEDURE
DILUTE SAMPLE
Minimum Residual, 1.0 mg/LMinimum Depletion, 2.0 mg/LAt Least Two Dilutions
Calculation of Range of Acceptable BOD Results
BOD Sample =Depletion
X 300 mLSample Volume
Minimum BOD =Minimum Depletion
X 300 mLSample Volume
Minimum BOD =2.0
X 300Sample Volume
Minimum BOD = 600Sample Volume
Lowest (Minimum) Acceptable Results – Lowest Acceptable Depletion
Example
What is the Lowest Acceptable BOD results if 20 mL of sample is used?
Minimum BOD = 600Sample Volume
Minimum BOD = 60020
Minimum Acceptable BOD = 30 mg/L
Minimum BOD That May Be Reported =600
Sample Volume
Example 2
What is the Lowest Acceptable BOD results if 150 mL of sample is used?
Minimum BOD = 600Sample Volume
Minimum BOD = 600150
Minimum Acceptable BOD = 4 mg/L
Calculation of Range of Acceptable BOD Results
Maximum BOD =D.O. In – 1.0
X 300 mLSample Volume
Maximum BOD =7.0
X 300Sample Volume
Maximum BOD = 2100Sample Volume
Highest (Maximum) Acceptable Results
ASSUMING Initial D.O. of 8.0 mg/L
Lowest Acceptable Residual
– Highest Acceptable Depletion
Depletion = 8.0 - 1.0 = 7.0
Example
What is the highest Acceptable BOD results if 20 mL of sample is used?
Maximum BOD = 2100Sample Volume
Maximum BOD = 210020
Maximum Acceptable BOD = 105 mg/L
Maximum BOD That May Be Reported =2100
Sample Volume
Example 2
What is the highest Acceptable BOD results if 150 mL of sample is used?
Maximum BOD = 2100Sample Volume
Maximum BOD = 2100150
Maximum Acceptable BOD = 14 mg/L
Maximum BOD That May Be Reported =2100
Sample Volume
Calculation of Range of Acceptable BOD Results
Minimum BOD = 600Sample Volume
Lowest (Minimum) Acceptable Results – Lowest Acceptable Depletion
Summary
Highest (Maximum) Acceptable Results
Lowest Acceptable Residual
– Highest Acceptable Depletion
Maximum BOD = 2100Sample Volume
(Assuming D.O. In =8.0 mg/L
Calculation of Range of Acceptable BOD Results
Minimum BOD = 600Sample Volume
Wait A Minute
Maximum BOD = 2100Sample Volume
600 X 3.5 = 2100600 X 3.5 = 2100
So (assuming D.O. In is 8.0)
Minimum BOD x 3.5 = Maximum BODMinimum BOD x 3.5 = Maximum BOD
Calculation of Range of Acceptable BOD Results
Minimum BOD = 600Sample Volume
Lowest (Minimum) Acceptable Results – Lowest Acceptable Depletion
Summary (again)
Highest (Maximum) Acceptable Results
Lowest Acceptable Residual
– Highest Acceptable Depletion
(Assuming D.O. In =8.0 mg/L
Maximum BOD = 3.5 X Minimum BOD
Example
What is the Lowest Acceptable BOD results if 30 mL of sample is used?
Minimum BOD = 60030 = 20 mg/L
What is the Highest Acceptable BOD results if 30 mL of sample is used?
20 mg/L X 3.5 = 70 mg/L
Total Range when using a 30 mL sample:
20 to 70 mg/L
Total Range when using a 100 mL sample = 6 to 21 mg/L
Total Range when using a 150 mL sample = 4 to 14 mg/L
Total Range when using 100 mL and 150 mL (two Bottles)
Total Range when using a 50 mL sample = 12 to 42 mg/L
= 4 to 21 mg/L
Total Range when using 50 mL and 150 mL (two Bottles)
= 4 to 42 mg/L
OVERLAP From 6 to 14 mg/L
OVERLAP From 12 to 14 mg/L
Total Range when using a 25 mL sample = 24 to 84 mg/L
Total Range when using a 125 mL sample = 4.8 to 16.8 mg/L
Total Range when using 25 mL and 125 mL (two Bottles)
NO: Does Not Include 16.8 to 24 mg/L
= 4.8 to 84 mg/L
Range To Wide (No Overlap)
?
Calculate Range of Acceptable BOD Results
Use Two Volumes that Expand the RangeBut
Give a “Comfortable” Overlap
Calculate Range of Acceptable BOD Results
Use Two Volumes that Expand the RangeBut
Give a “Comfortable” Overlap
Calculate Range of Acceptable BOD Results
Use Two Volumes that Expand the RangeBut
Give a “Comfortable” Overlap
Calculation of Range of Dilutions forAcceptable BOD Results
Prepared ByMichigan Department of Environmental Quality
Operator Training and Certification Unit
