Determination of Growth Rate and Yield of Nitrifying Bacteria by Measuring Carbon Dioxide Uptake Rate

Abstract

Nitrifier growth parameters-the maximum growth rate (l Amax ) and yield (Y A )-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 l Amax values for the Nitrobacter and Nitrosomonas cultures were 0.67 6 0.03 day 21 and 0.54 6 0.09 day 21 , while the Y A values were 0.072 6 0.01 g volatile suspended solids (VSS) Á g nitrogen (N) 21 and 0.14 6 0.02 gVSS Á gN 21 , respectively. For the activated sludge sample, l Amax was observed to increase with pH (l Amax 5 0.72 Á 3.3 (pH-7.1) ) over the range 6.8 to 7.1. All l Amax and Y A values determined by this method were similar to those previously reported. Compared with other l Amax and Y A estimation methods, this method allows for unique l Amax and Y A estimations for given conditions from a single experiment. Water Environ. Res., 79, 2437Res., 79, (2007.

Biochar-mediated reductions in greenhouse gas emissions from soil amended with anaerobic digestates

“…It is likely that a shift in the microbial community accounted for the lack of any correlation between biomass-C and respiration in the ADF 3 treatment, since these soils demonstrated the highest amount of nitrification and denitrification. When attributing respiratory output to C-use efficiency it should be noted that nitrifiers utilise CO 2 for biomass production and may constitute a loss of CO 2 [46]. In the current study, biochar had no observable effect on soil respiration which corroborates the findings of others [47].…”

Probing the stoichiometry of the nitrification process using the respirometric approach

“…Values for each step of the nitrification process were not provided in literature. In the sludge with 10-day SRT, the yield coefficient for ammonia oxidizers was 0.18 g-cell/g-N oxidized, which was close to the value determined by some researchers (Blackburne et al, 2007;Ahn et al, 2008), but significantly lower than the value provided by Furumai and Rittmann (1994). As listed in Table 2, nitrite oxidizers in the sludge with 10-day SRT had a much lower yield coefficient than ammonia oxidizers.…”

“…Nitrite-oxidizing bacteria were the only nitrite oxidizers in activated sludge, and no nitrite-oxidizing archaea were reported (You et al, 2009). The kinetics among different nitrifiers were significantly different from each other (Schramm et al, 1999;Kim and Kim, 2006;Dytczak et al, 2008), and it was very difficult to determine these kinetic constants using the pure-culture approach (Blackburne et al, 2007).…”

Achieving nitrite accumulation in a continuous system treating low-strength domestic wastewater: switchover from batch start-up to continuous operation with process control

“…Yuan et al (2008) also pointed out that the positive feedback loop due to the control system eventually resulted in the complete washout of NOB. Moreover, AOB have a higher yield coefficient compared to NOB (Blackburne et al 2007;Philips et al 2002), which would lead to the more net growth numbers of AOB than NOB. So the real-time aeration duration control was an efficient approach to obtain quickly the nitrite accumulation and to achieve sludge population optimization during batch operation conditions.…”