Scope:

Total oxygen demand (TOD) is the amount of dissolved oxygen demanded by aerobic organisms to break down organic material present in a given water sample. BOD reduction is used as a gauge of the effectiveness of wastewater treatment plants. ASTM D6238-13 test method is used to determine total oxygen demand. It is particularly useful for measuring oxygen demand in certain industrial effluents and process streams. Its application for monitoring secondary sewage effluents is not established. 

Test Procedure:

In ASTM D6238-13 test method, the liquid sample is introduced into a carrier gas stream containing a fixed amount of oxygen flowing through a 900°C combustion tube. The oxidizable components in the liquid sample are converted to their stable oxides, leading to a reduction in oxygen levels. The reduction in the oxygen concentration in the carrier gas is detected by an oxygen sensor. The oxidizable components in a liquid sample introduced into a carrier gas stream containing a fixed amount of oxygen flowing through a 900°C combustion tube are converted to their stable oxides. The momentary reduction in the oxygen concentration in the carrier gas is detected by an oxygen sensor and indicated on a digital display or recorded. The TOD for the sample is determined by comparing the peak height to a calibration curve of peak heights for TOD standard solutions. 

Data:

The total oxygen demand (TOD) of the water sample is reported.