Running Waters - Mathematics and Statistics for the Environment - page 565

19.6.2.2 Seeded BOD Procedure

1. Select those dilutions that meet the test criteria.

2. Calculate the BOD for each selected dilution using the following formula:

( ) −

DO − DO Seed correctio n × 300 mL

start final

BOD(mg/L) = (19.9)

Sample volume(mL)

where DO start and DO inal are in mg/L.
Seed correction is calculated using

BOD
300 mL

start

Seed correction(mg/L) = × Seed in sample dilution (mL) (19.10)

■ EXAMPLE 19.6
Problem: A series of seed dilutions were prepared in 300-mL BOD bottles using seed material
(settled raw wastewater) and unseeded dilution water. The average BOD for the seed material was
204 mg/L. One milliliter of the seed material was also added to each bottle of a series of sample
dilutions. Given the data for two samples in the table below, calculate the seed correction factor (SC)
and BOD of the sample.

DO (mg/L)

Bottle No. Sample (mL) Seed/Bottle (mL) Initial Final Depletion (mg/L)

12 50 1 8.0 4.6 3.4

13 75 1 7.7 3.9 2.8

Solution: First calculate the BOD of each milliliter of seed material:

204 mg/L
300 mL

BODper mL seed = = 068 . mg/L BO Dper mL seed

Calculate the seed correction (SC) factor:

Seed correctionfactor = (068 mg/L BODper m Lseed) 1mLseed per bottle) × = 0.68 mg/L

Calculate the BOD of each sample dilution:

3 . 4068 − ×= .

Bottle 12 BOD(mg/L) = 300 16.3 mg/L

50 mL

3 . 8068 − .

Bottle 13 BOD(mg/L) = × 30 0 = 12.5 mg/L

75 mL

Finally, calculate reported BOD:

16 3125 . + .

ReportedBOD = = 14.4 mg/L

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