BOD Analysis
Biochemical Oxygen Demand (BOD)
BOD provides a measure of the impact of a waste (water) on the oxygen content in a receiving water body. Wastes (organic matter, "food") are broken down (decomposed, oxidized, metabolized) by microbial organisms (aerobic bacteria), frequently referred to as "bugs", who require oxygen for this monumental effort. BOD is an "estimate" of the "food" available in a sample. The more "food" present in a sample the more oxygen that will be required and the higher the BOD, the more rapidly oxygen is depleted from a water body. This means less DO is available to aquatic organisms who then become stressed, suffocate, and die (fish kill). Simply put, BOD gives an indication of the degree of which water is polluted.
BOD is commonly required testing for wastewater treatment plants to measure waste loads, efficiency and effectiveness of BOD removal, control of plant processes, and most importantly the concentration of the effluent that is discharged to water bodies..
Dissolved oxygen (DO) is measured at the beginning of the analysis and after a 5 day, in-the-dark, 20 'C incubation period. The difference of the DO between the beginning and end of analysis is used to calculate the BOD.
The BOD test is a bioassay. Bioassay is a shorthand form, commonly used term for biological assay and is a type of in vitro experiment. Bioassays are typically conducted to measure the effects of a substance on a living organism. Bioassays may be qualitative or quantitative, the latter often involving an estimation of the concentration or potency of a substance by measurement of the biological response that it produces.
Standard Methods 5210B-2001: