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Biochemical oxygen demand (BOD) is the amount of dissolved oxygen needed by aerobic biological organisms in a body of water to break down organic material present in a given water sample at certain temperature over a specific time period. The term also refers to a chemical procedure for determining this amount. This is not a precise quantitative test, although it is widely used as an indication of the organic quality of water. The BOD value is most commonly expressed in milligrams of oxygen consumed per litre of sample during 5 days of incubation at 20 °C and is often used as a robust surrogate of the degree of organic pollution of water.

BOD can be used as a gauge of the effectiveness of wastewater treatment plants. It is listed as a conventional pollutant in the U.S. Clean Water Act.

BOD is similar in function to chemical oxygen demand (COD), in that both measure the amount of organic compounds in water. However, COD is less specific, since it measures everything that can be chemically oxidized, rather than just levels of biologically active organic matter.

The problem with BOD in monitoring an activated sludge plant is that the result takes 5 days to come through. By then conditions may have changed and responding to the measured BOD may not still be appropriate.COD is quicker but as  Randa states it responds to things which do not biodegrade, or do so slowly. Instrumental systems which give a predicted BOD based on the early stage kinetics are available.

Hello,  

May I ask how it is that you plan to run the test? Currently I run the BOD for water quality in my lab  Are you planning to run it against a standard? How do you plan to keep the samples?  In our lab we use a g/ga standard as quality control and we keep samples at 4 celsius immediately after arrival at lab to minimize the changes in the sample. It is important to work with water aerated for 72 hours as controls if you plan to use blanks to determine seed quality. If you plan to run the test I would be happy to help you.    

I believe BOD cum COD are good parameters to evaluate organic loading as pollutant.

They are very limited since pollution in its widest sense also implies inorganics such as nitrate, phosphate, heavy metals, essentials trace element in excess, pesticides residue etc.. Indeed all these contaminants are of relevance in relation to the point source pollution!

Thanks Tiwari your documents helped me

Odum (1970) division the water quality of water bodies according to the values of the BOD5 to the following:

BOD5 = 2 is clean

BOD5 = 5 or more isdoubtful.

Hi can anyone help me with this numerical

How much water resource is required for a person/year to keep better water quality? under the following condition;

water consumption per person per day:250lit

BOD of treated water by biological wastewater treatment process:5mg/l

BOD value of maintenance of biological ecosystem in the aquatic environment:4mg/l