del Rio, A. V., Campos, J. L., Da Silva, C., Pedrouso, A., & Mosquera-Corral, A. (2019). Determination of the intrinsic kinetic parameters of ammonia-oxidizing and nitrite-oxidizing bacteria in granular and flocculent sludge. Sep. Purif. Technol., 213, 571–577.
Abstract: The different oxygen affinities of ammonia-oxidizing (AOB) and nitrite-oxidizing bacteria (NOB) are often used to define the operational strategy to achieve partial nitritation (PN) required before the anammox (AMX) process. For this purpose, apparent kinetic parameters are mainly used in the case of granular sludge, which can lead to errors when defining the operational conditions to obtain only nitritation (avoiding nitratation). In the present study, a mathematical methodology is proposed to determine the intrinsic kinetic parameters of AOB and NOB in granular sludge based on data obtained by respirometric assays. Additionally, the oxygen affinity constant (K-O2) and maximum specific rate (r(max)) of flocculent and granular sludge sample, produced under mainstream and sidestream conditions were determined at various temperatures (15, 20 and 30 degrees C). The results show that for granules, the intrinsic K-O2 and r(max) values were lower and higher, respectively, than the apparent values. Furthermore, the K-O2 values for flocs and granules at all of the tested temperatures were lower for NOB than for AOB. The values obtained for the kinetic parameters indicated that it is impossible to maintain partial nitritation by only controlling the dissolved oxygen concentration.
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Da Silva, C., Astals, S., Peces, M., Campos, J. L., & Guerrero, L. (2018). Biochemical methane potential (BMP) tests: Reducing test time by early parameter estimation. Waste Manage., 71, 19–24.
Abstract: Biochemical methane potential (BMP) test is a key analytical technique to assess the implementation and optimisation of anaerobic biotechnologies. However, this technique is characterised by long testing times (from 20 to > 100 days), which is not suitable for waste utilities, consulting companies or plants operators whose decision-making processes cannot be held for such a long time. This study develops a statistically robust mathematical strategy using sensitivity functions for early prediction of BMP first-order model parameters, i.e. methane yield (B-0) and kinetic constant rate (k). The minimum testing time for early parameter estimation showed a potential correlation with the k value, where (i) slowly biodegradable substrates (k <= 0.1 d(-1)) have a minimum testing times of >= 15 days, (ii) moderately biodegradable substrates (0.1 < k < 0.2 d(-1)) have a minimum testing times between 8 and 15 days, and (iii) rapidly biodegradable substrates (k > 0.2 d(-1)) have testing times lower than 7 days. (C) 2017 Elsevier Ltd. All rights reserved.
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Read-Daily, B. L., Sabba, F., Pavissich, J. P., & Nerenberg, R. (2016). Kinetics of nitrous oxide (N2O) formation and reduction by Paracoccus pantotrophus. AMB Express, 6, 7 pp.
Abstract: Nitrous oxide (N2O) is a powerful greenhouse gas emitted from wastewater treatment, as well as natural systems, as a result of biological nitrification and denitrification. While denitrifying bacteria can be a significant source of N2O, they can also reduce N2O to N-2. More information on the kinetics of N2O formation and reduction by denitrifying bacteria is needed to predict and quantify their impact on N2O emissions. In this study, kinetic parameters were determined for Paracoccus pantotrophus, a common denitrifying bacterium. Parameters included the maximum specific reduction rates, (q) over cap, growth rates, (mu) over cap, and yields, Y, for reduction of NO3- (nitrate) to nitrite (N2O-), N2O- to N2O, and N2O to N-2, with acetate as the electron donor. The (q) over cap values were 2.9 gN gCOD(-1) d(-1) for NNO3- to NO2-, 1.4 gN gCOD(-1) d(-1) for N2O-to N2O, and 5.3 gN gCOD(-1) d(-1) for N2O to N-2. The (mu) over cap values were 2.7, 0.93, and 1.5 d(-1), respectively. When N2O and NO3- were added concurrently, the apparent (extant) kinetics, (q) over cap (app), assuming reduction to N-2, were 6.3 gCOD gCOD(-1) d(-1), compared to 5.4 gCOD gCOD(-1) d(-1) for NO3- as the sole added acceptor. The (mu) over cap (app) was 1.6 d(-1), compared to 2.5 d(-1) for NO3- alone. These results suggest that NO3- and N2O were reduced concurrently. Based on this research, denitrifying bacteria like P. pantotrophus may serve as a significant sink for N2O. With careful design and operation, treatment plants can use denitrifying bacteria to minimize N2O emissions.
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