2007-03-04 20:27:27 · 1 answers · asked by ee 1 in Science & Mathematics ➔ Chemistry
COD or Chemical Oxygen Demand is the total measurement of all chemicals in the water that can be oxidized. BOD- Biochemical Oxygen Demand is supposed to measure the amount of food (or organic carbons) that bacteria can oxidize.
A COD test measures all organic carbon with the exception of certain aromatics (benzene, toluene, phenol, etc.) which are not completely oxidized in the reaction. COD is a chemically chelated/thermal oxidation reaction, and therefore, other reduced substances such as sulfides, sulfites, and ferrous iron will also be oxidized and reported as COD. NH3-N (ammonia) will NOT be oxidized as COD. So, if the sample contains significant quantities of the types of substance listed above, BOD may exceed COD.
Hope this helps.
2007-03-04 21:06:35 · answer #1 · answered by JJ 7 · 1⤊ 0⤋