Biochemical Oxygen Demand
In "dilution BOD" the oxygen content of a sample is measured with a dissolved oxygen sensor before and after an incubation period of 5 days. The difference between the measurements is the BOD5 value; this is the official EPA method.
In "BOD self-checks" with the respirometer, the reduction in oxygen causes a definite pressure difference that can be measured by a pressure sensor. This practical method is very easy to perform.
Both methods are very different, but the measurements correlate directly to the discharge seen at municipal wastewater treatment facilities. Both methods require the samples to be kept at 20 °C for 5 days. WTW offers a wide range of temperature controlled incubators.
As environmental consciousness increases, microbiological degradability tests have become increasingly important, from soil surveys from waste sites to environmental impact surveys to characterize new chemical substances. The necessary respiration measurements for anaerobic or aerobic degradation can be easily performed using the high performance OxiTop®-C systems. WTW offers a wide range of application specific packages complete with the appropriate sample vessels.