BOD / COD / TOC / TOX

BOD:

The biochemical oxygen demand (BOD) determination is an empirical test in which standardized laboratory procedures are used to determine the relative oxygen requirements of wastewaters, effluents, and polluted waters. The test has its widest application in measuring waste loadings to treatment plants and in evaluating the BOD-removal efficiency of such treatment systems.

BOD testing measures the molecular oxygen utilized during a specified incubation period for the biochemical degradation of organic material and the oxygen used to oxidize inorganic material such as sulfides and ferrous iron. It also may measure the amount of oxygen used to oxidized reduced forms of nitrogen.

COD:

Chemical oxygen demand (COD) is defined as the amount of a specified oxidant that reacts with the sample under controlled conditions. The quantity of oxidant consumed is expressed in terms of its oxygen equivalence. COD is often used as a measurement of pollutants in wastewater and natural waters.

TOC:

Total organic carbon, (TOC), is a measure of organic carbon in a sample

TOX:

Total organic halogen, (TOX), is indicative of disinfection by-products and other synthetic chemical contamination. Halogenated compounds that contribute to a TOX result include, but ate not limited to: the trihalomethanes (THMs), organic solvents such as trichloroethene, tetrachloroethene, and other halogenated alkanes and alkenens, chlorinated and brominated pesticides and herbicides, polychlorinated biphenyls (PCBs), chlorinated aromatics such as hexachlorobenzene and 2,4-dichlorophenol, and high-molecular-weight, partially chlorinated aquatic humic substances.

TOX measurement is an inexpensive and useful method for screening large numbers of samples before specific, often more complex analyses, for extensive field surveying for pollution by certain classes of synthetic organic compounds in natural water; for mapping the extent of organohlide contamination in groundwater; for monitoring the breakthrough of some synthetic organic compounds in water treatment processes; and for estimating the level of formation of chlorinated organic by-products after disinfection.

( Source: Standard Methods for the Examination of Water and Wastewater, 21st edition 2005 )