First, you need to identify the type and general characteristics of the wastewater and look up the typical range of COD and BOD5 for that wastewater from reliable sources.
To measure the mentioned parameters, please refer to the standard methods for wastewater analysis.
There are several methods for measuring BOD5. The most widely employed, the physicochemical method uses a dissolved oxygen probe to measure the O2 concentration in a representative sample, the operation being repeated after a 5-day incubation period. BOD5 is the difference between the two measurements. Incubate a sealed water sample at 20oC for five days, followed by measuring the difference in oxygen content before and after incubation. The Five-day BOD, or BOD5, is measured by the quantity of oxygen consumed by microorganisms during a five-day period, and is the most common measure of the amount of biodegradable organic material in, COD is measured via a laboratory assay in which a sample is incubated with a strong chemical oxidant for a specified time interval and at constant temperature (usually 2 h at 150°C). The most commonly used oxidant is potassium dichromate, which is used in combination with boiling sulphuric acid. The ratio within the chemical oxygen demand (COD) and the biological oxygen demand over 5 days (BOD5) indicates the level of biodegradability of a sample. A low ratio COD/BOD5 (less than 2.0 or 2.5) indicates a high biodegradability, what means that it can be treated easily by a biological treatment.
Just follow your college/university laboratory manual. Or, download this 'CPCB Water and Wastewater Analysis Manuals'.
This is an easy to follow book.
Dear Omar...... For wastewater, ww, the overall composition must be considered. Any measurement must deal with the whole ww and the filtrate. This is to report that the COD or BOD values are related to suspended matter or to the clear ww. The filtration, thus, must be the most important step. The two separated phases, will be digested and the measurement is carried out. Good luck
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