Standard Test Method for Total Oxygen Demand in Water

Importancia y uso:

5.1 The measurement of oxygen demand parameters is critical to the control of process wastewaters. Biochemical oxygen demand (BOD) and chemical oxygen demand (COD) analyzers have long time cycles and in the case of COD analyzers use corrosive reagents with the inherent problem of disposal. Total oxygen demand analysis is faster, approximately 3 min, and uses no liquid reagents in its analysis.

5.2 TOD can be correlated to both COD and BOD, providing effective on-line control.

5.3 TOD offers several features which make it a more attractive measurement than carbon monitoring using total carbon (TC) or total organic carbon (TOC) analyzers. TOD is unaffected by the presence of inorganic carbon. TOD analysis will also indicate noncarbonaceous materials that consume or contribute oxygen. For example, the oxygen demand of ammonia, sulfite and sulfides will be reflected in the TOD measurement. Also, since the actual measurement is oxygen consumption, TOD reflects the oxidation state of the chemical compound (that is, urea and formic acid have the same number of carbon atoms, yet urea has five times the oxygen demand of formic acid).

Subcomité:

D19.06

Referida por:

E2635-22, E2635-22

Volúmen:

11.02

Número ICS:

13.060.50 (Examination of water for chemical substances)

Palabras clave:

BOD; COD; laboratory analyzer, online monitor; oxygen demand; total oxygen demand; TOD;