Which method is commonly used to determine the BOD of wastewater?

The method of dilution and incubation is commonly used to determine the Biochemical Oxygen Demand (BOD) of wastewater because it effectively measures the amount of oxygen that microorganisms will consume while decomposing organic matter in a sample over a specified period.

In this procedure, a sample of wastewater is diluted with a specific amount of distilled water to create conditions optimal for microbial activity. This diluted sample is then incubated at a controlled temperature (usually around 20°C) for a set time period, typically five days (known as BOD5). During this incubation, the bacteria present in the water consume the organic materials and, as a result, deplete the oxygen in the sample. The decrease in dissolved oxygen from the initial measurement to the final measurement after the incubation period is calculated to determine the BOD, which reflects the level of organic pollution in the water.

Filtration, chromatography, and distillation are not appropriate methods for determining BOD. Filtration removes particulate matter and would not give an accurate representation of the biological activity in the presence of soluble organic material. Chromatography is used to separate and analyze complex mixtures of substances but does not measure oxygen demand. Distillation, primarily used for separating liquids based on boiling points, does not relate to measuring