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.”
Anaerobic Biomass Activity Tests
The methane production activity of anaerobic sludges is related to the history of the sludge, the biomass yield from the wastewater the sludge has been treating, the fraction of methanogens, and the presence of toxic substances. Best performance can be achieved from an anaerobic treatment plant if the operator measures the Specific Methanogenic Production (SMP) of the biomass contained within the sludge. The SMP is measured by placing a known amount of biomass in a respirometer vessel, adding a known amount of substrate – usually acetic acid – to the bottle at concentrations sufficient to cause maximum biomass activity, and measuring the resulting methane. The SMP is expressed as the COD equivalent of the methane production rate per gram of volatile solids, or gm COD/gm VSS/d. An example of an SMP measurement is shown in the figure below. Figure A shows methane production measured over a three–day period using a Challenge AER-200 aerobic/anaerobic respirometer. Figure B shows the calculated specific methane production rate. The maximum specific methane production rate represents the SMA – or the activity – of this sludge sample. SMAs between 1.0 and 2.0 indicate a highly active biomass. An SMA of 1.5 g COD/g VSS–d indicates that the biomass is 25% methanogens by weight.