Testimonials
“We have found the performance of the system to be quite satisfying and user friendly. We are currently running low level O2 uptake experiments and are impressed with the sensitivity of the instrument.”
“I have found the performance of the Challenge AER-200 to be unmatched. The precise measurement of oxygen consumption, homogenous mass transfer of test materials, and constant and consistent operating temperature have enabled me to obtain extremely accurate test results, particularly as compared to other respirometer systems. I find the Challenge system to be extremely user friendly.”
Measuring Short–Term BOD
Using the Challenge Technology OUR–BOD respirometer
Measurement of oxygen uptake rates in activated sludge processes is essential to their satisfactory operation. Traditionally, oxygen uptake rates (OUR) have been determined by using a dissolved oxygen probe in a BOD bottle. While this method is rapid, it provides only a snapshot, at a single point in time, of the oxygen uptake rate reaction in a treatment plant. Much more can be learned about the operation of a treatment plant by measuring the oxygen uptake rate over a period ranging from one to four hours after adding wastewater to the mixed liquor. The resulting pattern of oxygen uptake rate can be used to assess biodegradation patterns, to determine the impact of various wastes on treatment plant performance, and to provide a short–term measure of BOD.
An example of a typical OUR test is shown below using data collected with a challenge AER–200 respirometer system. The data show the background OUR for the MLSS and a 60/40 mixture of wastewater and mixed liquor(A). As indicated, the maximum OUR was around 30mg/L-hr. This value corresponds to the value that would be obtained by a single measure using a DO probe. The difference between the oxygen uptake of a sample plus seed and seed alone produces a short term BOD curve (B), or the data can be used to produce an estimate of the standard 5–day dilution BOD.