Description:
<jats:p>Nitrifier growth parameters—the maximum growth rate (μ <jats:sub><jats:italic>Amax</jats:italic></jats:sub>) and yield (<jats:italic>Y</jats:italic> <jats:sub><jats:italic>A</jats:italic></jats:sub>)—were estimated by measuring the rate of carbon dioxide uptake and additional rates of oxygen uptake and ammonia (or nitrite) use. Batch tests in a combined titrimetric and offgas analyzer with enriched Nitrobacter and Nitrosomonas cultures and an activated sludge sample were performed. The measured μ <jats:sub><jats:italic>Amax</jats:italic></jats:sub> values for the Nitrobacter and Nitrosomonas cultures were 0.67 ± 0.03 day <jats:sup>−1</jats:sup> and 0.54 ± 0.09 day <jats:sup>−1</jats:sup>, while the <jats:italic>Y</jats:italic> <jats:sub><jats:italic>A</jats:italic></jats:sub> values were 0.072 ± 0.01 g volatile suspended solids (VSS) · g nitrogen (N) <jats:sup>−1</jats:sup> and 0.14 ± 0.02 gVSS · gN <jats:sup>−1</jats:sup>, respectively. For the activated sludge sample, μ <jats:sub><jats:italic>Amax</jats:italic></jats:sub> was observed to increase with pH (μ <jats:sub><jats:italic>Amax</jats:italic></jats:sub> = 0.72 · 3.3 <jats:sup>(pH‐7.1)</jats:sup>) over the range 6.8 to 7.1. All μ <jats:sub><jats:italic>Amax</jats:italic></jats:sub> and <jats:italic>Y</jats:italic> <jats:sub><jats:italic>A</jats:italic></jats:sub> values determined by this method were similar to those previously reported. Compared with other μ <jats:sub><jats:italic>Amax</jats:italic></jats:sub> and <jats:italic>Y</jats:italic> <jats:sub><jats:italic>A</jats:italic></jats:sub> estimation methods, this method allows for unique μ <jats:sub><jats:italic>Amax</jats:italic></jats:sub> and <jats:italic>Y</jats:italic> <jats:sub><jats:italic>A</jats:italic></jats:sub> estimations for given conditions from a single experiment.</jats:p>