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BOD test bottles at the laboratory of a wastewater treatment plant. Biochemical oxygen demand (also known as BOD or biological oxygen demand) is an analytical parameter representing the amount of dissolved oxygen (DO) consumed by aerobic bacteria growing on the organic material present in a water sample at a specific temperature over a specific time period.
The Streeter–Phelps equation determines the relation between the dissolved oxygen concentration and the biological oxygen demand over time and is a solution to the linear first order differential equation [1]
Because the Ultimate BOD is so time consuming, the 5-day BOD has been almost universally adopted as a measure of relative pollution effect. There are also many different COD tests of which the 4-hour COD is probably the most common. There is no generalized correlation between the 5-day BOD and the ultimate BOD.
The difference in DO and the dilution factor are used to calculated BOD 5. The resulting number (usually reported in parts per million or milligrams per liter) is useful in determining the relative organic strength of sewage or other polluted waters. The BOD 5 test is an example of analysis that determines classes of materials in a sample.
The most common application of COD is in quantifying the amount of oxidizable pollutants found in surface water (e.g. lakes and rivers) or wastewater. COD is useful in terms of water quality by providing a metric to determine the effect an effluent will have on the receiving body, much like biochemical oxygen demand (BOD).
If the base value is taken as 60 grams of BOD per person per day, then the equation to calculate PE from an industrial wastewater is: P E = B O D l o a d f r o m i n d u s t r y [ k g d a y ] 0.060 [ k g i n h a b ⋅ d a y ] {\displaystyle PE={\dfrac {BOD\ load\ from\ industry\ \left[{\dfrac {kg}{day}}\right]}{0.060\ \left[{\dfrac {kg}{inhab ...
An EPA scientist samples water in Florida Everglades. Samples of water from the natural environment are routinely taken and analyzed as part of a pre-determined monitoring program by regulatory authorities to ensure that waters remain unpolluted, or if polluted, that the levels of pollution are not increasing or are falling in line with an agreed remediation plan.
The reactions take place by the joint participation of several microorganisms living within the pond. The organic matter is measured as biochemical oxygen demand (BOD). BOD values in the pond effluent are lower than in the influent, reflecting the removal of organic matter. This pond biome uses organic matter from the wastewater as food.