Challenge Technology articles

The CHALLENGE AER-200 Respirometer System consists of one or more biological reaction vessels, gas flow measuring cells, and a computer. The gas measuring base contains eight flow cells and associated interconnecting circuitry. As gas flows through each cell under the influence of a slight pressure caused by gas production in the reaction vessel, bubbles of a fixed volume are formed in the lower section of the ceil. These bubbles in turn pass through a detection section where a counter is act

Biodegradation tests usually involve comparison of the oxygen uptake of a test sample – or gas production for anoxic or anaerobic tests – to that for a readily biodegradable control substrate (usually acetic acid, ethanol, or aniline). While biodegradation characteristics can vary among chemical types and wastewater sources, typical patterns are shown in Figure A. The curve labeled CONTROL represents oxygen uptake of readily b

Extant Kinetics Of Mixed Wastewaters

OUR fingerprints can be used to estimate kinetic parameters for the wastewater constituents as shown in Figure A and B below. Wastewater A contained one group of readily degraded compounds and one group that was degraded at lower rates. A third region of oxygen uptake was caused by nitrification. Kinetic modeling suggested that biodegradation of each constituent followed classical Monod kinetics. Wastewater B contained a group of re

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 know

Assessing Nutrient Deficiencies

The Challenge AER-200 respirometer system is ideally suited for assessing the occurrence of nutrient deficiencies as illustrated in the figure below. In this case various amounts of a mixture of nutrients and trace minerals were added to different respirometer vessels that received 25 mL of wastewater plus seed organisms. The resulting oxygen uptake reactions show increasing oxygen uptake with additional nutrients

Biochemical Methane Potential (BMP) tests involve addition of test chemicals or wastewater samples of concern to an anaerobic culture that is contained within a sealed vessel. Methane or total gas production are measured over periods ranging from 1 to 60 days without addition of new chemical or wastewater sample. Modern BMP tests usually involve multiple additions of substrate or wastewater to anaerobic reactors over 3 to 60 days to assess the ab

Situations often occur where rapid assessment of potential toxicity to a treatment process is needed, for example, when hauled wastes are discharged to treatment plants. In these cases, the test wastewater is added in various ratios to a mixed liquor suspension along with an organic substrate that is known to degrade well by the test culture. Acetate seems to work well in most cases. Increases in oxygen uptake above that