1. Dissolved Oxygen and Biochemical Oxygen Demand Analyses
Prepared By
Michigan Department of Environmental Quality
Operator Training and Certification Unit
Note: These Procedures are available in the OTCU Laboratory manual which is available on the OTCU website.

2. Amount of “FREE” Oxygen
Dissolved Oxygen
D.O.
Amount of “FREE” Oxygen O2
In the Water
Required By :
FISH
MICROORGANISMS
( Bacteria)

3. RESPIRATION Organic Matter Converted to: Carbon Dioxide Water and
CH2O + O CO2 + H2O

4. RESPIRATION Reason for Treatment Basis of Secondary Treatment
CH2O + O CO2 + H2O
Reason for Treatment
Basis of
Secondary Treatment
Basis of BOD Analysis

5. BIOLOGICAL Oxidation of Nitrogen
Nitrification
BIOLOGICAL Oxidation of Nitrogen
From
AMMONIA
(NH3) to
NITRITE
( NO2) to
NITRATE
(NO3)
NH3 + O NO2
+ O NO3

6. Oxygen Demand Reduction Ammonia Removal (toxic)
NITRIFICATION
NH3 + O NO2
+ O NO3
May be Required:
Oxygen Demand Reduction
Ammonia Removal (toxic)

7. Treatment Plant Effluents
Reason for D.O. Analysis
Used in BOD Analysis
Treatment Processes
Treatment Plant Effluents
Receiving Stream

8. Maximum D.O. Concentrations in Water (Saturation)
Temperature 0C
Max. Concentration
mg/L

9. SAMPLE COLLECTION
Sample
Atmosphere
21 %
0 to 10 mg/L
210,000 mg/L

10. SAMPLE COLLECTION

11. SAMPLE COLLECTION

12. Do Not Splash Sample in Air Let Air Circulate in Sample
Do Not AERATE Sample NO
YES
Do Not Splash Sample in Air or
Let Air Circulate in Sample

13. Biochemical Oxygen Demand
B.O.D.
Biochemical Oxygen Demand
The Quantity of Oxygen Used in the Biochemical Oxidation of Organic Material.
Under:
Specified Time
Specified Temperature
Specified Conditions
5 Days
200 C
In the Dark
In the Presence
of Bacteria

14. Measured Volume of Wastewater is Added to BOD Bottle.
Contains:
Organics
Ammonia
Bacteria
CxHYOz
NH3
CxHYOz
Bacteria
CxHYOz
NH3
CxHYOz
CxHYOz

15. Dilution Water Contains:
Dilution Water Added
Dilution Water Contains:
Nutrients O2
CxHYOz
Oxygen O2
CxHYOz
Bacteria
NH3 O2
Measure
D.O. Concentration
CxHYOz O2
NH3 O2
CxHYOz
CxHYOz O2

16. Measure D.O. Concentration
Incubate 5 Days
Some Oxygen Used:
Respiration
CxHYOz+ O H2O + CO2
Nitrification O2
NH3 + O NO3 O2
Measure
D.O. Concentration O2

17. (Of What Is In The Bottle)
Measure Oxygen Loss
(Demand)
D.O. Day D.O. Day 5
= Oxygen Demand
CxHYOz+ O H2O + CO2 O2
NH3 + O NO3 O2
(Of What Is In The Bottle) O2

18. Free of Oxygen Demanding Substances
BOD
REAGENTS
Distilled Water
High Quality
Free of Toxic Material
Free of Oxygen Demanding Substances

19. FILL BOTTLE (with dilution water)
BOD PROCEDURE, (cont.)
FILL BOTTLE (with dilution water)
MEASURE INITIAL D.O.
STOPPER
(No Air Bubbles)
SEAL
(Water and Cover)

20. BOD PROCEDURE, (cont.) INCUBATE MEASURE FINAL D.O.
5 Days ± 6 hour
MEASURE FINAL D.O.
(wash bottles)

21. NOT USED IN CALCULATIONS
DILUTION WATER BLANK
CHECK ON QUALITY
MAXIMUM DEPLETION
0.2 mg/L
NOT USED IN CALCULATIONS

22. = Oxygen Demand of Diluted Sample
B.O.D. Calculation
D.O. In - D.O. Out
= DEPLETION
= Oxygen Demand of Diluted Sample
C1 X V1 = C2 X V2
Sample
BOD
Sample
Volume X =
BOD
Diluted
Diluted
Volume X
Volume
Diluted
BOD Diluted X
BOD Sample =
Sample Volume
Depletion
BOD Sample = X
300 mL
Sample Volume

23. Minimum Depletion - 2.0 mg/L Minimum Residual - 1.0 mg/L
B.O.D. mg/L =
D.0. DEPLETION (mg/L)
X 300 mL
SAMPLE VOLUME (mL)
D.O. DEPLETION =
D.O. Initial -
D.O. 5-Day
Minimum Depletion mg/L
Minimum Residual mg/L