Journal articles: 'Oxygen volumetric mass transfer coefficient (kLa)'

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Rakoczy, Rafał, Maciej Konopacki, Marian Kordas, Radosław Drozd, and Karol Fijałkowski. "Influence of rotating magnetic field on gas-liquid volumetric mass transfer coefficient." Chemical and Process Engineering 38, no. 3 (September 1, 2017): 423–32. http://dx.doi.org/10.1515/cpe-2017-0032.

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Abstract The main objective of these experiments was to study the oxygen mass transfer rate through the volumetric mass transfer coefficient (kLa) for an experimental set-up equipped with a rotating magnetic field (RMF) generator and various liquids. The experimental results indicated that kLa increased along the magnetic strength and the superficial gas velocity. Mathematical correlations defining the influence of the considered factors on kLa were proposed.

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Potůček, František. "Oxygen transfer during batch cultivation in an airlift tower fermentor." Collection of Czechoslovak Chemical Communications 54, no. 12 (1989): 3213–19. http://dx.doi.org/10.1135/cccc19893213.

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Oxygen transfer was studied in an airlift tower fermentor with motionless mixers (Kenics type). The intensity of oxygen transfer was characterized by its volumetric mass transfer coefficient, kLa, which was determined by the balance method. Experimental data of kLa were described by correlation equation and compared with results obtained for the airlift fermentor without motionless mixers with respect to energetic consumption. In addition, growth characteristics of the yeast culture Turulopsis ethanolitolerans cultivated on ethanol were also investigated.

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Baquero-Rodríguez, Gustavo Andrés, and Jaime A. Lara-Borrero. "The Influence of Optic and Polarographic Dissolved Oxygen Sensors Estimating the Volumetric Oxygen Mass Transfer Coefficient (KLa)." Modern Applied Science 10, no. 8 (June 15, 2016): 142. http://dx.doi.org/10.5539/mas.v10n8p142.

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Aeration is usually the most energy intensive part of the wastewater treatment process. Optimizing the aeration system is essential for reducing energy costs. Field tests oriented to estimate parameters related to oxygen transfer are a common approach to compare aeration systems. The aim of this research is to assess the effect of dissolved oxygen probe lag on oxygen transfer parameter estimation. Experimental procedures regarding to process automation and control were applied to quantify dissolved oxygen probe lag. We have measured oxygen transfer in clean water, under a wide range of conditions (airflow rate, diffuser characteristics and diffuser density), with optic and polarographic sensors for dissolved oxygen measurement. The oxygen transfer was measured as per ASCE Standard procedures. Nonparametric statistical tests were used to compare the estimated volumetric mass transfer coefficient KLa with different sensors. According to the results, there is not significant influence of the probe lag (also known as time constant) or probe characteristics on the parameters used to assess oxygen transfer efficiency. This fact has great relevance in common practice of aerobic process for wastewater treatment because dissolved oxygen monitoring is used as an input for decision making related to the energy optimization in the aeration system. Findings from these tests contradict previous studies which claim that lag time in polarographic sensors for the dissolved oxygen measurement can bias estimate KLa.

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Knezevic, Milena, and Dragan Povrenovic. "Influence of fluid-mechanical characteristics of the system on the volumetric mass transfer coefficient and gas dispersion in three-phase system." Chemical Industry 68, no. 4 (2014): 483–90. http://dx.doi.org/10.2298/hemind130629072k.

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Distribution of gas bubbles and volumetric mass transfer coefficient, Kla, in a three phase system, with different types of solid particles at different operation conditions were studied in this paper. The ranges of superficial gas and liquid velocities used in this study were 0,03-0,09 m/s and 0-0,1 m/s, respectively. The three different types of solid particles were used as a bed in the column (glass dp=3 mm, dp=6 mm; ceramic dp=6 mm). The experiments were carried out in a 2D plexiglas column, 278 x 20,4 x 500 mm and in a cylindrical plexiglas column, with a diameter of 64 mm and a hight of 2000 mm. The Kla coefficient increased with gas and liquid velocities. Results showed that the volumetric mass transfer coefficient has a higher values in three phase system, with solid particles, compared with two phase system. The particles properties (diameter and density) have a major impact on oxygen mass transfer in three phase systems.

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Li, Shaobai, Jungeng Fan, Shuang Xu, Rundong Li, and Jingde Luan. "The influence of pH on gas-liquid mass transfer in non-Newtonian fluids." Chemical Industry and Chemical Engineering Quarterly 23, no. 3 (2017): 321–27. http://dx.doi.org/10.2298/ciceq160705046l.

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In this study, the effect of pH on the mass transfer of oxygen bubble swarms in non-Newtonian fluids was experimentally studied. The volumetric liquid side mass transfer coefficient (kLa), liquid side mass transfer coefficient (kL), and specific interfacial area (a) were investigated. The pH was regulated by the addition of hydrochloric acid and sodium hydroxide (NaOH). It was found that the kLa increased with the gas flow rate increasing and decreased with the apparent viscosity of the liquid increasing. In the case of pH < 7, a marginal effect of pH on the gas?liquid mass transfer was observed, but when pH value was higher than 7, mass transfer was promoted with the increase of pH value. Via investigating the impact of pH on kL and a, the variation of mass transfer at pH > 7 was attributed to the decomposition of the Xanthan molecular structure by the hydroxyl of NaOH.

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Wierzchowski, Kamil, Paweł Sobieszuk, and Maciej Pilarek. "Oxygen Transfer Effects in a Two-Phase System of an Aqueous Phase and Liquid Perfluorochemical Subjected to Continuous Wave-Assisted Agitation in Disposable Bioreactor." Energies 14, no. 14 (July 20, 2021): 4381. http://dx.doi.org/10.3390/en14144381.

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Systems of two immiscible liquid phases—aqueous phase (i.e., distilled water (dH2O) or phosphate-buffered saline (PBS)) and liquid perfluorochemical (i.e., perfluorodecalin (PFD))—were subjected to wave-assisted agitation, i.e., oscillatory rocked, in a disposable bag-like container in a ReadyToProcess WAVETM25 bioreactor, to recognize oxygen transfer effects and effectivity of the surface aeration. According to the DoE methodology, values of the volumetric liquid-side mass transfer (kLa) coefficient for dH2O, PBS, dH2O-PFD, and PBS-PFD systems were determined for the whole range of operating parameters of the WAVE 25 bioreactor. A significantly higher maximal value of kLa was found for waving dH2O than for dH2O-PFD (i.e., 0.00460 s−1 vs. 0.00331 s−1, respectively) compared to more equal maximal values of kLa reached for PBS and PBS-PFD (0.00355 s−1 vs. 0.00341 s−1, respectively). The interface development factor (f) depended on the interfacial area a, and the enhancement factor (EPFD), depending on kLa, was introduced to quantitatively identify the mass transfer effects in the systems of waving two immiscible liquids. The phase of PFD was identified as the reservoir of oxygen. Dimensional correlations were proposed for the prediction of the kLa coefficient, in addition to the f and EPFD factors. The presented correlations, and the set of kLa values, can be directly applied to predict oxygen transfer effects reached under continuous oscillatory rocked systems containing aqueous phase and liquid perfluorochemical.

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Zhao, Zemeng, Zhibang Liu, Yang Xiang, Moses Arowo, and Lei Shao. "Removal of Dissolved Oxygen from Water by Nitrogen Stripping Coupled with Vacuum Degassing in a Rotor–Stator Reactor." Processes 9, no. 8 (August 1, 2021): 1354. http://dx.doi.org/10.3390/pr9081354.

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Oxygen is a harmful substance in many processes because it can bring out corrosion and oxidation of food. This study aimed to enhance the removal of dissolved oxygen (DO) from water by employing a novel rotor–stator reactor (RSR). The effectiveness of the nitrogen stripping coupled with vacuum degassing technique for the removal of DO from water in the RSR was investigated. The deoxygenation efficiency (η) and the mass transfer coefficient (KLa) were determined under various operating conditions for the rotational speed, liquid volumetric flow rate, gas volumetric flow rate, and vacuum degree. The nitrogen stripping coupled with vacuum degassing technique achieved values for η and KLa of 97.34% and 0.0882 s−1, respectively, which are much higher than those achieved with the vacuum degassing technique alone (η = 89.95% and KLa = 0.0585 s−1). A correlation to predict the KLa was established and the predicted KLa values were in agreement with the experimental values, with deviations generally within 20%. The results indicate that RSR is a promising deaerator thanks to its intensification of gas–liquid contact.

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Behnisch, J., A. Ganzauge, S. Sander, M. P. Herrling, and M. Wagner. "Improving aeration systems in saline water: measurement of local bubble size and volumetric mass transfer coefficient of conventional membrane diffusers." Water Science and Technology 78, no. 4 (August 14, 2018): 860–67. http://dx.doi.org/10.2166/wst.2018.358.

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Abstract In this study, for the first time, the influence of the design of conventional membrane diffusers on the volumetric mass transfer coefficient (kLa) and bubble size in tap water (TW) and saline water (SW) was investigated (up to 15 g/L NaCl). By using a new analytical approach, kLa and the bubble size along the ascent of the bubble swarm were measured simultaneously and in real time. The results show that in TW, after collision bubbles merge into larger bubbles by coalescence. In SW, coalescence is inhibited by salt. Due to the smaller bubble size, kLa increases to more than double compared to TW. The results show that in SW, membrane diffusers with dense slit patterns and smaller slit lengths are to be recommended in order to enable improved utilization of oxygen in saline water.

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Ha, Sanghyun, Ho Kim, Ho Chun, In Hwang, Jong-Hee Lee, Jin-Cheol Kim, In Kim, and Hae Park. "Effect of Oxygen Supply on Surfactin Production and Sporulation in Submerged Culture of Bacillus subtilis Y9." Applied Sciences 8, no. 9 (September 14, 2018): 1660. http://dx.doi.org/10.3390/app8091660.

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Fermentation parameters for surfactin production and sporulation in a submerged culture of Bacillus subtilis Y9 with various oxygen transfer rates in 5 L jar fermenters were investigated. The oxygen-uptake rate (OUR) was positively correlated with volumetric surfactin productivity. When OUR value increased from 0 to 250 s−1, productivity increased up to 45 mg/L·h; however, no further increase was observed at OUR values above 255 s−1. The volumetric mass transfer coefficient KLa increased with increasing agitation speed. However, a reduction in surfactin production was observed at the highest agitation speed of 500 rpm. Productivity sharply decreased after spore appearance, and remained low until the end of the culture. A mesh-type sparger was installed to generate microsized air bubbles. When the system was operated at 400 rpm with the mesh-type sparger, KLa was higher than that at 500 rpm with an original sparger. Under agitation at 400 rpm with the mesh-type sparger, productivity was maintained above 42.3 mg/L·h until 24 h, resulting in the highest surfactin concentration of 875 mg/L. Thus, a mesh-type sparger promotes KLa, leading to an increase in productivity.

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Liew, Kelly Chung Shi, Athina Rasdi, Wiratni Budhijanto, Mohd Hizami Mohd Yusoff, Muhmmad Roil Bilad, Norazanita Shamsuddin, Nik Abdul Hadi Md Nordin, and Zulfan Adi Putra. "Porous Venturi-Orifice Microbubble Generator for Oxygen Dissolution in Water." Processes 8, no. 10 (October 9, 2020): 1266. http://dx.doi.org/10.3390/pr8101266.

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Microbubbles with slow rising speed, higher specific area and greater oxygen dissolution are desired to enhance gas/liquid mass transfer rate. Such attributes are very important to tackle challenges on the low efficiency of gas/liquid mass transfer that occurs in aerobic wastewater treatment systems or in the aquaculture industries. Many reports focus on the formation mechanisms of the microbubbles, but with less emphasis on the system optimization and assessment of the aeration efficiency. This work assesses the performance and evaluates the aeration efficiency of a porous venturi-orifice microbubble generator (MBG). The increment of stream velocity along the venturi pathway and orifice ring leads to a pressure drop (Patm > Pabs) and subsequently to increased cavitation. The experiments were run under three conditions: various liquid velocity (QL) of 2.35–2.60 m/s at fixed gas velocity (Qg) of 3 L/min; various Qg of 1–5 L/min at fixed QL of 2.46 m/s; and free flowing air at variable QLs. Results show that increasing liquid velocities from 2.35 to 2.60 m/s imposes higher vacuum pressure of 0.84 to 2.27 kPa. They correspond to free-flowing air at rates of 3.2–5.6 L/min. When the system was tested at constant air velocity of 3 L/min and under variable liquid velocities, the oxygen dissolution rate peaks at liquid velocity of 2.46 m/s, which also provides the highest volumetric mass transfer coefficient (KLa) of 0.041 min−1 and the highest aeration efficiency of 0.287 kgO2/kWh. Under free-flowing air, the impact of QL is significant at a range of 2.35 to 2.46 m/s until reaching a plateau KLa value of 0.0416 min−1. The pattern of the KLa trend is mirrored by the aeration efficiency that reached the maximum value of 0.424 kgO2/kWh. The findings on the aeration efficiency reveals that the venturi-orifice MBG can be further optimized by focusing on the trade-off between air bubble size and the air volumetric velocity to balance between the amount of available oxygen to be transferred and the rate of the oxygen transfer.

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Seidel, Stefan, and Dieter Eibl. "Influence of Interfacial Force Models and Population Balance Models on the kLa Value in Stirred Bioreactors." Processes 9, no. 7 (July 7, 2021): 1185. http://dx.doi.org/10.3390/pr9071185.

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Optimal oxygen supply is vitally important for the cultivation of aerobically growing cells, as it has a direct influence on cell growth and product formation. A process engineering parameter directly related to oxygen supply is the volumetric oxygen mass transfer coefficient kLa. It is the influences on kLa and computing time of different interfacial force and population balance models in stirred bioreactors that have been evaluated in this study. For this investigation, the OpenFOAM 7 open-source toolbox was utilized. Firstly, the Euler–Euler model with a constant bubble diameter was applied to a 2L scale bioreactor to statistically examine the influence of different interfacial models on the kLa value. It was shown that the kL model and the constant bubble diameter have the greatest influence on the calculated kLa value. To eliminate the problem of a constant bubble diameter and to take effects such as bubble breakup and coalescence into account, the Euler–Euler model was coupled with population balance models (PBM). For this purpose, four coalescence and five bubble breakup models were examined. Ultimately, it was established that, for all of the models tested, coupling computational fluid dynamics (CFD) with PBM resulted in better agreement with the experimental data than using the Euler–Euler model. However, it should be noted that the higher accuracy of the PBM coupled models requires twice the computation time.

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Morales-Rodelo, Keidy, Mario Francisco, Hernan Alvarez, Pastora Vega, and Silvana Revollar. "Collaborative Control Applied to BSM1 for Wastewater Treatment Plants." Processes 8, no. 11 (November 16, 2020): 1465. http://dx.doi.org/10.3390/pr8111465.

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This paper describes a design procedure for a collaborative control structure in Plant Wide Control (PWC), taking into account the existing controllable parameters as a novelty in the procedure. The collaborative control structure includes two layers, supervisory and regulatory, which are determined according to the dynamics hierarchy obtained by means of the Hankel matrix. The supervisory layer is determined by the main dynamics of the process and the regulatory layer comprises the secondary dynamics and controllable parameters. The methodology proposed is applied to a wastewater treatment plant, particularly to the Benchmark Simulation Model No 1 (BSM1) for the activated sludge process, comparing the results with the use of a Model Predictive Controller in the supervisory layer. For determining controllable parameters in the BSM1 control, a new specific oxygen mass transfer model in the biological reactor has been developed, separating the kLa volumetric mass transfer coefficient into two controllable parameters, kL and a.

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Mohd Sauid, Suhaila, Jagannathan Krishnan, Tan Huey Ling, and Murthy V. P. S. Veluri. "Enhancement of Oxygen Mass Transfer and Gas Holdup Using Palm Oil in Stirred Tank Bioreactors with Xanthan Solutions as Simulated Viscous Fermentation Broths." BioMed Research International 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/409675.

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Volumetric mass transfer coefficient (kLa) is an important parameter in bioreactors handling viscous fermentations such as xanthan gum production, as it affects the reactor performance and productivity. Published literatures showed that adding an organic phase such as hydrocarbons or vegetable oil could increase thekLa. The present study opted for palm oil as the organic phase as it is plentiful in Malaysia. Experiments were carried out to study the effect of viscosity, gas holdup, andkLaon the xanthan solution with different palm oil fractions by varying the agitation rate and aeration rate in a 5 L bench-top bioreactor fitted with twin Rushton turbines. Results showed that 10% (v/v) of palm oil raised thekLaof xanthan solution by 1.5 to 3 folds with the highestkLavalue of 84.44 h−1. It was also found that palm oil increased the gas holdup and viscosity of the xanthan solution. ThekLavalues obtained as a function of power input, superficial gas velocity, and palm oil fraction were validated by two different empirical equations. Similarly, the gas holdup obtained as a function of power input and superficial gas velocity was validated by another empirical equation. All correlations were found to fit well with higher determination coefficients.

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Asselin, C., Y. Comeau, and Q. A. Ton-That. "Alpha correction factors for static aerators and fine bubble diffusers used in municipal facultative aerated lagoons." Water Science and Technology 38, no. 3 (August 1, 1998): 79–85. http://dx.doi.org/10.2166/wst.1998.0180.

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The alpha correction factor (KLa process water/KLa clean water; where KLa is the volumetric oxygen mass transfer coefficient) was evaluated for 4 kinds of static aerators and 2 kinds of fine bubble diffusers used in municipal facultative aerated lagoons. For this purpose, a 40 m3 steel tank was filled (3.1 m side water depth) with clean or process water. The process water consisted of “mixed liquor” from a municipal facultative aerated lagoon divided into a cascade of four identical basins that were 3.5 m deep. Results showed that in the last three basins, the alpha correction factors were relatively high, being between 0.85 to 0.95 for any type of aeration device. In the first lagoon, however, the alpha correction factors were between 0.70 and 0.90 for static aerators and about 0.70 for fine bubble diffusers. Furthermore, at the inlet of the first basin, the alpha factor was as low as 0.59 for a static aerator and 0.26 for a fine bubble diffuser, due to the composition of the “mixed liquor”. It was shown that the alpha correction factor that should be used for the design of aeration systems for facultative aerated lagoons should be lower in the first basin of a series of basins and could be higher than 0.85 for the downstream basins.

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Tribe, L. A., C. L. Briens, and A. Margaritis. "Determination of the volumetric mass transfer coefficient (kLa) using the dynamic ?gas out-gas in? method: Analysis of errors caused by dissolved oxygen probes." Biotechnology and Bioengineering 46, no. 4 (May 20, 1995): 388–92. http://dx.doi.org/10.1002/bit.260460412.

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Yu, Jian, and Pradeep Munasinghe. "Gas Fermentation Enhancement for Chemolithotrophic Growth of Cupriavidus necator on Carbon Dioxide." Fermentation 4, no. 3 (August 9, 2018): 63. http://dx.doi.org/10.3390/fermentation4030063.

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Cupriavidus necator, a facultative hydrogen-oxidizing bacterium, was grown on carbon dioxide, hydrogen, and oxygen for value-added products. High cell density and productivity were the goal of gas fermentation, but limited by gas substrates because of their low solubility in the aqueous medium solution. Enhancement of gas fermentation was investigated by (i) adding n-hexadecane as a gas vector to increase the volumetric mass transfer coefficient (kLa) and gas solubility, (ii) growing C. necator under a raised gas pressure, and (iii) using cell mass hydrolysates as the nutrients of chemolithotrophic growth. In contrast to previous studies, little positive but negative effects of the gas vector were observed on gas mass transfer and cell growth. The gas fermentation could be significantly enhanced under a raised pressure, resulting in a higher growth rate (0.12 h−1), cell density (18 g L−1), and gas uptake rate (200 mmole L−1 h−1) than a fermentation under atmospheric pressure. The gain, however, was not proportional to the pressure increase as predicted by Henry’s law. The hydrolysates of cell mass were found a good source of nutrients and the organic nitrogen was equivalent to or better than ammonium nitrogen for chemolithotrophic growth of C. necator on carbon dioxide.

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KAYHKO, JARI, KARI PELTONEN, HEIKKI MUTIKAINEN, RIKU KOPRA, HANNU ELORANTA, ANNA PESONEN, and ADRIAAN VAN HEININGEN. "The role of gas dispersion in the oxygen delignification process." May 2021 20, no. 5 (June 1, 2021): 321–28. http://dx.doi.org/10.32964/tj20.5.321.

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Oxygen delignification is an essential part of the pulp production process. Delignification occurs with the aid of alkali and dissolved oxygen. Dissolved oxygen is obtained by dispersing oxygen gas into the pulp suspension by using efficient mixers. Little is known about the state of oxygen gas dispersion and its effect on oxy-gen delignification kinetics and efficiency. This paper will present the results for the effect of gas bubble size on the performance of oxygen delignification. The results are mainly based on detailed studies made in a Finnish hardwood mill where the oxygen bubble size distribution could be altered at the feed of the reactor. An essential aspect of these studies was the use of a new continuous inline gas bubble size measurement system to simultaneously determine the bubble size distribution at the feed and top of the reactor. Information about oxygen consumption in the reactor could also be obtained through the bubble size measurements. Accordingly, these studies quantify the effect of oxygen bubble size on the kappa reduction of the pulp. The effect of different chemical factors on the oxygen bubble size is also studied. Finally, the relationship between the gas bubble size and the liquid phase oxygen mass transfer coefficient (kLa) is presented. This connects the bubble size to the kappa reduction rate. Based on the presented modeling approach and the evaluation of practical factors that are not taken into account in the modeling, it was concluded that the volumetric average oxygen bubble size should preferably be smaller than 0.2 mm in practice. The information obtained with the new gas bubble size measurement system and the presented modeling approach give a very new basis for understanding, monitoring, adjusting, and designing oxygen delignification processes.

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Banerjee, Uttam Chand. "Effect of stirrer speed, aeration rate and cell mass concentration on volumetric oxygen transfer coefficients (KLa) in the cultivation of Curvularia lunata in a batch reactor." Biotechnology Techniques 7, no. 10 (October 1993): 733–38. http://dx.doi.org/10.1007/bf00152622.

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Kojic, Predrag, Ivana Sijacki, Natasa Lukic, Dragica Jovicevic, Svetlana Popovic, and Dragan Petrovic. "Volumetric gas-liquid mass transfer coefficient in an external-loop airlift reactor with inserted membrane." Chemical Industry and Chemical Engineering Quarterly 22, no. 3 (2016): 275–84. http://dx.doi.org/10.2298/ciceq150622041k.

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The effects of the inserted membrane in the downcomer of an external-loop airlift reactor, the gas sparger type (single orifice and sinter plate) and added alcohol (ethanol, n-butanol, or n-hexanol) on the volumetric gas-liquid mass transfer coefficient (kLa) were studied. Due to the presence of the membrane in the downcomer, kLa did not change significantly; the differences were smaller than 10%. The highest values of the kLa were obtained using the sinter plate. It was found that the addition of small amounts of alcohol increased the mass transfer. Using our experimental results and the data of other authors, the feed-forward back propagation neural network for prediction of kLa in external-loop airlift reactors with alcohol solutions was proposed.

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Fu, Xian Wei, Chun Mian Lin, and Ya Ping Guo. "Influences of COD Model Components in ASM2D on Oxygen Mass Transfer Coefficient." Advanced Materials Research 777 (September 2013): 347–51. http://dx.doi.org/10.4028/www.scientific.net/amr.777.347.

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Chemical Oxygen Demand was split into SA (volatile acid / fermentation products), SF (fermentable, readily bio-degradable organic substrates), XS (slowly biodegradable substrates), SI (Inert soluble organic material) and XI (Inert particulate organic material). Research of how these model components affect the oxygen transfer coefficient (KLa) was studied in this paper. The results showed that with the increase of SA, KLa decreased, KLa first decreased when SF was in 25-100 mgCOD/L, then it increased in 100-200 mg/L,then it decreased again. XS has a poor regularity and slight infect on oxygen mass transfer, XI, SI may inhibit the oxygen transfer.

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Winkler, Kurt, František Kaštánek, and Jan Kratochvíl. "Influence of liquid properties on mass transfer coefficients in bubble columns." Collection of Czechoslovak Chemical Communications 53, no. 4 (1988): 763–70. http://dx.doi.org/10.1135/cccc19880763.

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The gas phase holdup, the specific interfacial area a, and the liquid-side volumetric mass transfer coefficient kLa have been determined for two selected binary systems water-butanol and butanol-2-ethylhexanol in a short bubble column of 150 mm i.d. at gas phase velocities (air) in the range of uG = (0.31-2.52) . 10-2 m s-1. The kLa-uG dependences show characteristic maxima which only partially can be explained by molecular and surface force interactions, induced by the liquid phase. The main parameter, influencing the kLa-values, is a. At small gas velocities some irregularities in the Sauter diameter d32 and in the values of separated kL are observed.

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Mandl, Martin, Eva Pakostova, and Lenka Poskerova. "Minimum Aeration in Acidithiobacillus ferrooxidans Cultures Required to Maintain Substrate Oxidation without Oxygen Limitation." Advanced Materials Research 825 (October 2013): 414–17. http://dx.doi.org/10.4028/www.scientific.net/amr.825.414.

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The volumetric oxygen transfer coefficient (kLa) was used to define the conditions necessary for minimum aeration and to eliminate potential oxygen limitation in bioleaching cultures ofAcidithiobacillus ferrooxidans. The Michaelis constants for oxygen were 1.07 and 0.71 μmol O2l-1for the oxidation of ferrous iron and elemental sulphur, respectively. The critical oxygen concentration, below which oxygen limitation occurred, was determined to be 6.25 and 3.125 μmol O2l-1for the oxidation of ferrous iron and elemental sulphur, respectively. The (kLa)critvalues required to maintain oxygen-unlimited substrate oxidation for ferrous iron and elemental sulphur were 7.70 and 4.88 h-1, respectively.

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Šulc, Radek, and Jan Dymák. "Hydrodynamics and Mass Transfer in a Concentric Internal Jet-Loop Airlift Bioreactor Equipped with a Deflector." Energies 14, no. 14 (July 18, 2021): 4329. http://dx.doi.org/10.3390/en14144329.

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The gas–liquid hydrodynamics and mass transfer were studied in a concentric tube internal jet-loop airlift reactor with a conical bottom. Comparing with a standard design, the gas separator was equipped with an adjustable deflector placed above the riser. The effect of riser superficial gas velocity uSGR on the total gas holdup εGT, homogenization time tH, and overall volumetric liquid-phase mass transfer coefficient kLa was investigated in a laboratory bioreactor, of 300 mm in inner diameter, in a two-phase air–water system and three-phase air–water–PVC–particle system with the volumetric solid fraction of 1% for various deflector clearances. The airlift was operated in the range of riser superficial gas velocity from 0.011 to 0.045 m/s. For the gas–liquid system, when reducing the deflector clearance, the total gas holdup decreased, the homogenization time increased twice compared to the highest deflector clearance tested, and the overall volumetric mass transfer coefficient slightly increased by 10–17%. The presence of a solid phase shortened the homogenization time, especially for lower uSGR and deflector clearance, and reduced the mass transfer coefficient by 15–35%. Compared to the gas–liquid system, the noticeable effect of deflector clearance was found for the kLa coefficient, which was found approx. 20–29% higher for the lowest tested deflector clearance.

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Painmanakul, Pisut, Jidapa Wachirasak, Marupatch Jamnongwong, and Gilles Hebrard. "Theoretical Prediction of Volumetric Mass Transfer Coefficient (kLa) for Designing an Aeration Tank." Engineering Journal 13, no. 3 (November 12, 2009): 13–28. http://dx.doi.org/10.4186/ej.2009.13.3.13.

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Liu, Kan, John R. Phillips, Xiao Sun, Sayeed Mohammad, Raymond L. Huhnke, and Hasan K. Atiyeh. "Investigation and Modeling of Gas-Liquid Mass Transfer in a Sparged and Non-Sparged Continuous Stirred Tank Reactor with Potential Application in Syngas Fermentation." Fermentation 5, no. 3 (August 13, 2019): 75. http://dx.doi.org/10.3390/fermentation5030075.

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Syngas (mixture of CO, H2 and CO2) fermentation suffers from mass transfer limitation due to low solubility of CO and H2 in the liquid medium. Therefore, it is critical to characterize the mass transfer in syngas fermentation reactors to guide in delivery of syngas to the microorganisms. The objective of this study is to measure and predict the overall volumetric mass transfer coefficient, kLa for O2 at various operating conditions in a 7-L sparged and non-sparged continuous stirred-tank reactor (CSTR). Measurements indicated that the kLa for O2 increased with an increase in air flow rate and agitation speed. However, kLa for O2 decreased with the increase in the headspace pressure. The highest kLa for O2 with air sparged in the CSTR was 116 h−1 at 600 sccm, 900 rpm, 101 kPa, and 3 L working volume. Backmixing of the headspace N2 in the sparged CSTR reduced the observed kLa. The mass transfer model predicted the kLa for O2 within 10% of the experimental values. The model was extended to predict the kLa for syngas components CO, CO2 and H2, which will guide in selecting operating conditions that minimize power input to the bioreactor and maximize the syngas conversion efficiency.

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Barber, Tyler W., Ken I. Ashley, Donald S. Mavinic, and Ken Christison. "Superoxygenation: analysis of oxygen transfer design parameters using high-purity oxygen and a pressurized column." Canadian Journal of Civil Engineering 42, no. 10 (October 2015): 737–46. http://dx.doi.org/10.1139/cjce-2015-0037.

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There remains significant potential for improvement in oxygen transfer efficiency, which can account for 60% of water and wastewater treatment energy requirements. This research examined superoxygenation, or aerating water under pressure with high-purity oxygen gas. Examined were the effects superoxygenation has on five key aeration design parameters: the mass transfer coefficient (KLa), saturation concentration ([Formula: see text]), standard oxygen transfer rate (SOTR), standard aeration efficiency (SAE), and standard oxygen transfer efficiency (SOTE). This research compared values under pressures of 0, 50, 100, 150, and 200 kPa using air and pressure swing adsorption (PSA) generated oxygen. It was found that with increasing pressure for both air and PSA oxygen: KLa decreased, [Formula: see text] increased, SOTR and SAE remained constant, and SOTE increased. While comparing air and PSA oxygen, oxygen was found to have a similar KLa, larger [Formula: see text], SOTR, and SOTE, and a lower SAE. It was concluded that superoxygenation is a viable method for increasing oxygen transfer and could potentially reduce oxygenation costs in water treatment processes.

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Barboza, M., M. Zaiat, and C. O. Hokka. "General relationship for volumetric oxygen transfer coefficient ( kLa) prediction in tower bioreactors utilizing immobilized cells." Bioprocess Engineering 22, no. 2 (February 9, 2000): 0181–84. http://dx.doi.org/10.1007/s004490050029.

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Hui, K. W. Leo, and Sheldon J. B. Duff. "Factors Affecting Oxygen Transfer in Lab-Scale Activated Sludge Reactors Treating Bleached Kraft Mill Effluent." Water Quality Research Journal 33, no. 3 (August 1, 1998): 439–56. http://dx.doi.org/10.2166/wqrj.1998.025.

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Abstract In aerobic biological wastewater treatment processes, oxygen must be transferred from the gas phase to the liquid phase to support oxidation of dissolved organics and endogenous metabolism by the bacteria. Power required to supply this oxygen in suspended growth systems can represent a significant fraction of the operating costs of such processes. In this study, the interfacial mass transfer coefficient KLa for water was found to be reduced by up to 28% (average 13%) by the addition of antifoaming agent. KLa values were reduced by up to 43% (average 26%) by the dissolved organics in primary treated bleached kraft mill effluent. There was no significant difference between the KLa for water and biologically treated bleached kraft mill effluent.

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Gavrilescu, M., R. V. Roman, and V. Efimov. "The volumetric oxygen mass transfer coefficient in antibiotic biosynthesis liquids." Acta Biotechnologica 13, no. 1 (1993): 59–70. http://dx.doi.org/10.1002/abio.370130114.

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Orhan, Ramazan, and Gülbeyi Dursun. "Investigation of α-Amylase Production with Bacillus amyloliquefaciens in a Cocurrent Downflow Contacting Reactor." International Journal of Chemical Reactor Engineering 14, no. 5 (October 1, 2016): 1081–87. http://dx.doi.org/10.1515/ijcre-2016-0005.

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Abstract The cocurrent downflow contacting reactor (CDCR) has a high oxygen transfer rate by providing the effective the gas-liquid contact. This property is an advantage for enzyme production. In this study, the CDCR was used for the production of α-amylase by Bacillus amyloliquefaciens for different starch concentrations in the range of 7.5–17.5 g l–1 at constant air and liquid flow rates. The values of the volumetric oxygen transfer coefficient (kLa) and specific oxygen uptake rate ( ${{\rm{q}}_{{{\rm{O}}_2}}}$ ) were determined during enzyme production. It has been found that the starch concentration has great effect on the enzyme activity. Maximum enzyme activity (1,000 IU ml–1) was obtained in the fermentation broth containing of 15 g l–1 starch concentration at 37 °C and pH 7 for 28 h. The kLa and ${{\rm{q}}_{{{\rm{O}}_2}}}$ values were determined to be 175.83 h–1 and 47.5 mg O2 g–1cell h–1, respectively.

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Chen, Qing Chun, and Zhen Chen. "Neural Network Simulation for Mass Transfer Coefficient of Alcohol/Ether Fuel Direct Synthesis." Advanced Materials Research 781-784 (September 2013): 2400–2405. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.2400.

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The gas-liquid volumetric mass transfer coefficient was determined by the dynamic oxygen absorption technique using a polarographic dissolved oxygen probe and the gas-liquid interfacial area was measured using dual-tip conductivity probes in a bubble column slurry reactor. Feed-forward back propagation neural network models were employed to predict the gas-liquid volumetric mass transfer coefficient and liquid-side mass transfer coefficient for Alcohol/Ether fuel direct synthesis system in a commercial-scale bubble column slurry reactor. And the effects of various axial locations, superficial gas velocity and solid concentration on the gas-liquid volumetric mass transfer coefficient kLaL and liquid-side mass transfer coefficient kL were discussed in detail in the range of operating variables investigated.

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Taslim, Taslim, and Mohd Sobri Takriff. "Gas Holdup and Gas-Liquid Mass Transfer Investigations in an Oscillatory Flow in a Baffled Column." ASEAN Journal of Chemical Engineering 2, no. 1 (October 20, 2008): 7. http://dx.doi.org/10.22146/ajche.50797.

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Gas holdup and gas-liquid mass transfer were investigated in a vertical baffled column. Pure carbon dioxide (C02) was used as the dispersed phase and tap water was used as the continuous phase. Gas holdup and mass transfer rate of C02 were measured under semi-batch condition, while the liquid phase was measured in batch mode. Gas holdup was estimated as the volume fraction of the gas in the two-phase mixture in the column. Mass transfer was expressed in terms of the liquid-side volumetric mass transfer coefficient (kLa). The effects of oscillation frequency, oscillation amplitude and gas flow rate on gas holdup andmass transfer were also determined. The results showed that a significant increase in gas holdup and mass transfer could be achieved in an oscillatory baffled column compared to a bubble column. Gas holdup and mass transfer were correlated as a function of power density and superficial gas velocity. Keywords: gas holdup, mass transfer coefficient, power density, superficial gas velocity

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Suescun, J., and E. Ayesa. "Practical identification of the dissolved oxygen dynamic in activated sludge plants." Water Science and Technology 45, no. 4-5 (February 1, 2002): 397–404. http://dx.doi.org/10.2166/wst.2002.0634.

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This paper presents the application to a full-scale waste water treatment plant (WWTP) of a practical methodology to identify the oxygen supply and consumption terms, which regulate the dynamic behaviour of the dissolved oxygen concentration (SO) in activated sludge reactors. This methodology is based on a periodic adjustment of the selected model for oxygen mass-transfer coefficient (KLa) and a continuous estimation of the oxygen uptake rate (rO), maintaining constant the adjusted KLa model, in order to uncouple the effects that the consumption and supply terms have on the SO concentration. The adjustment phase of the KLa model is based on typified excitations of the system through the aeration system of the plant, which allow the estimation of KLa for different values of the aeration intensity parameter, for instance, air flow rate in air diffusion systems, revolution speed in surface aerators, etc. Once the KLa model is adjusted, it is possible to evaluate the KLa value in process conditions at any time. The continuous estimation of rO is carried out starting from the oxygen mass balance in the activatedsludge reactor. This practical methodology has been successfully verified in the Badiolegi WWTP in Azpeitia (Spain), which biological process consists of a double stage AB process, with two different aeration systems: fine pore air diffusers in the A-stage and surface aerators in the B-stage.

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Sastaravet, Prajak, Saret Bun, Kritchart Wongwailikhit, Nattawin Chawaloesphonsiya, Manabu Fujii, and Pisut Painmanakul. "Relative Effect of Additional Solid Media on Bubble Hydrodynamics in Bubble Column and Airlift Reactors towards Mass Transfer Enhancement." Processes 8, no. 6 (June 20, 2020): 713. http://dx.doi.org/10.3390/pr8060713.

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Many researchers have focused on multi-phase reactor development for improving mass transfer performance. However, solid particle addition in gas–liquid contactor for better oxygen mass transfer performance is still limited. Hence, this study aims to analyze the relative effect of different types of local solid media on the bubble hydrodynamic characteristics towards mass transfer enhancement in bubble columns (BCR) and airlift reactors (ALR). This was investigated by varying solid media types (ring, sphere, cylinder, and square), solid loadings (0%–15%), and superficial gas velocities (Vg) (2.6–15.3 × 10−3 m/s) in terms of the bubble hydrodynamic and oxygen mass transfer parameters. The result showed that bubble size distribution in BCR and ALR with additional plastic media was smaller than that without media addition, approximately 22%–27% and 5%–29%, respectively, due to the increase of the bubble breaking rate and the decrease of the bubble rising velocity (UB). Further, adding media in both reactors significantly decreased the UB value. Since media increased flow resistance, resulting in decreased liquid velocity, it can also be the moving bed to capture or block the bubbles from free rising. Therefore, oxygen mass transfer performance was investigated. The oxygen transfer coefficient (KLa) in BCR with solid media addition was enhanced up to 31%–56% compared to a non-addition case, while this enhancement was greater at higher solid loading due to its higher effective surface, resulting in a higher bubble break-up rate compared to the lower loading. In ALR, up to 38.5% enhanced KLa coefficient was archived after adding plastic media over the non-addition case. In conclusion, ring and cylinder media were found to be the most significant for improving KLa value in BCR and ALR, respectively, without extra energy.

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Myers, Shanna, Anna Mikola, Kati Blomberg, Anna Kuokkanen, and Diego Rosso. "Comparison of methods for nitrous oxide emission estimation in full-scale activated sludge." Water Science and Technology 83, no. 3 (January 27, 2021): 641–51. http://dx.doi.org/10.2166/wst.2021.033.

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Abstract Nitrous oxide (N2O) gas transfer was studied in a full-scale process to correlate liquid phase N2O concentrations with gas phase N2O emissions and compare methods of determining the volumetric mass transfer coefficient, KLa. Off-gas and liquid phase monitoring were conducted at the Viikinmäki wastewater treatment plant (WWTP) over a two-week period using a novel method for simultaneous measurement of dissolved and off-gas N2O and O2 from the same location. KLa was calculated with three methods: empirically, based on aeration superficial velocity, from experimentally determined O2 KLa, and using a static value of best fit. The findings of this study indicated trends in local emitted N2O consistently matched trends in local dissolved N2O, but the magnitude of N2O emissions could not be accurately estimated without correction. After applying a static correction factor, the O2 method, using experimentally determined O2 KLa, provided the best N2O emission estimation over the data collection period. N2O emissions estimated using the O2 method had a root mean square error (RMSE) of 70.5 compared against measured concentrations ranging from 3 to 1,913 ppm and a maximum 28% error. The KLa value, and therefore the method of KLa determination, had a significant impact on estimated emissions.

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36

Manikandan, S., N. Karthikeya, K. S. Suganthi, and K. S. Rajan. "Enhancement of Volumetric Mass Transfer Coefficient for Oxygen Transfer Using Fe2O3-Water Nanofluids." Asian Journal of Scientific Research 5, no. 4 (September 15, 2012): 271–77. http://dx.doi.org/10.3923/ajsr.2012.271.277.

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37

Mehmood, N., E. Olmos, P. Marchal, J. L. Goergen, and S. Delaunay. "Relation between pristinamycins production by Streptomyces pristinaespiralis, power dissipation and volumetric gas–liquid mass transfer coefficient, kLa." Process Biochemistry 45, no. 11 (November 2010): 1779–86. http://dx.doi.org/10.1016/j.procbio.2010.02.023.

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38

Eriksen, Niels Thomas, and Jens J�rgen L�nsmann Iversen. "Determination of the overall volumetric mass transfer coefficient kLa, by a temperature dependent change of gas solubility." Biotechnology Techniques 8, no. 6 (June 1994): 435–40. http://dx.doi.org/10.1007/bf00154317.

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39

Aroniada, Magdalini, Sofia Maina, Apostolis Koutinas, and Ioannis K. Kookos. "Estimation of volumetric mass transfer coefficient (kLa)—Review of classical approaches and contribution of a novel methodology." Biochemical Engineering Journal 155 (March 2020): 107458. http://dx.doi.org/10.1016/j.bej.2019.107458.

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40

Kratochvíl, Jan, Kurt Winkler, and Jindřich Zahradník. "Gas holdup and kLa in perforated-plate bubble columns in the presence of solid particles." Collection of Czechoslovak Chemical Communications 50, no. 1 (1985): 48–60. http://dx.doi.org/10.1135/cccc19850048.

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The effect of solid particles on values of volumetric liquid-side mass transfer coefficient, kLa, and gas holdup, εG, was determined in a bubble column 0.14 m in diameter within the range of solid phase concentration cS = 0-10% (mass). Experiments were carried out in air-water system at zero liquid flow rate, glass spheres of average diameters 24, 36, 50, 102, 142, 190, and 280 μm and fine Zn0 powder (average particle size 2.3 μm) were used as a solid phase. Perforated plate with holes diameter 1.6 mm and free plate area 0.2% was used for gas distribution, superficial gas velocities ranged between 0.036 and 0.215 m/s. Only negative effect of the gas holdup and kLa was observed in the whole range of experimental conditions, this effect being most pronounced in the region of small particle sizes (dS ⪬ 36 μm).

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41

Abdulmajeed, Basma Abbas, and Arwa Raad Ibrahim. "Mass Transfer Study for Bio-Synergy in Dairy Wastewater Treatment Plant." Journal of Engineering 24, no. 9 (August 30, 2018): 51. http://dx.doi.org/10.31026/j.eng.2018.09.04.

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The present study addresses the behavior of gases in cultivation media as an essential factor to develop the relationship between the microorganisms that are present in the same environment. This relationship was explained via mass transfer of those gases to be a reasonable driving force in changing biological trends. Stripping and dissolution of oxygen and carbon dioxide in water and dairy wastewater were investigated in this study. Bubble column bioreactor under thermal control system was constructed and used for these processes. The experimental results showed that the removal of gases from the culture media requires more time than the dissolution. For example, the volumetric mass transfer coefficient for the removal of oxygen is 1.67 min-1 while the volumetric mass transfer coefficient for dissolution the same gas is 3.18 min-1. The same thing occurred with carbon dioxide, where the data showed that the volumetric mass transfer coefficient of the dissolution of CO2 is 0.66 min-1 while the volumetric mass transfer coefficient for removal process is 0.374 min-1. However, the two processes (dissolution and removal) with CO2 take more time than that with O2. Therefore, the production of gases due to metabolic processes in bacteria or microalgae remains in culture’s media for a certain period even if that media is sparged by air. Thus, this will give enough time for both microorganisms to consume those gases. Keywords: Bioreactor, mass transfer, microalgae, aerobic bacteria The present study addresses the behavior of gases in cultivation media as an essential factor to develop the relationship between the microorganisms that are present in the same environment. This relationship was explained via mass transfer of those gases to be a reasonable driving force in changing biological trends. Stripping and dissolution of oxygen and carbon dioxide in water and dairy wastewater were investigated in this study. Bubble column bioreactor under thermal control system was constructed and used for these processes. The experimental results showed that the removal of gases from the culture media requires more time than the dissolution. For example, the volumetric mass transfer coefficient for the removal of oxygen is 1.67 min-1 while the volumetric mass transfer coefficient for dissolution the same gas is 3.18 min-1. The same thing occurred with carbon dioxide, where the data showed that the volumetric mass transfer coefficient of the dissolution of CO2 is 0.66 min-1 while the volumetric mass transfer coefficient for removal process is 0.374 min-1. However, the two processes (dissolution and removal) with CO2 take more time than that with O2. Therefore, the production of gases due to metabolic processes in bacteria or microalgae remains in culture’s media for a certain period even if that media is sparged by air. Thus, this will give enough time for both microorganisms to consume those gases.

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42

Deront, Marc, Falilou M. Samb, Nevenka Adler, and Paul Péringer. "Volumetric oxygen mass transfer coefficient in an upflow cocurrent packed-bed bioreactor." Chemical Engineering Science 53, no. 7 (March 1998): 1321–30. http://dx.doi.org/10.1016/s0009-2509(98)00003-7.

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Souza, Ellen Cristina, Dante Augusto Moraes, Thereza Christina Vessoni-Penna, Attilio Converti, and Ricardo Pinheiro de Souza Oliveira. "Volumetric Oxygen Mass Transfer Coefficient and Surface Tension in Simulated Salt Bioremediation Media." Chemical Engineering & Technology 37, no. 3 (February 4, 2014): 519–26. http://dx.doi.org/10.1002/ceat.201300592.

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44

Cachaza, Elena M., M. Elena Díaz, Francisco J. Montes, and Miguel A. Galán. "Analytical Solution of the Mass Conservation Equations in Gas−Liquid Systems: Applicability to the Evaluation of the Volumetric Mass Transfer Coefficient (kLa)." Industrial & Engineering Chemistry Research 47, no. 13 (July 2008): 4510–22. http://dx.doi.org/10.1021/ie800135h.

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45

Lopez-Hernandez, Yaremi, Carlos Orozco, Ines Garcia-Peña, Jorge Ramirez-Muñoz, and Luis Torres. "Influence of Sparger Type and Regime of Fluid on Biomass and Lipid Productivity of Chlorella vulgaris Culture in a Pilot Airlift Photobioreactor." Chemical & biochemical engineering quarterly 33, no. 1 (2019): 87–98. http://dx.doi.org/10.15255/cabeq.2018.1403.

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The effect of different types of spargers and the influence of the air flow rate on biomass and lipids production by Chlorella vulgaris was evaluated. These data allowed correlation of the hydrodynamic behavior of the photobioreactor with the byproducts production. The hydrodynamic characterization was developed by determining the mixing time (tM), hold-up, and total volumetric mass transfer coefficient of CO2, kLa(CO2)T, at increasing air flow rates for three different spargers: star-shaped, cross-shaped and porous glass surface sparger. The hydrodynamic characterization showed that the tM decreased, while the hold-up values and the kLa(CO2)T increased as a result of the increment in the volumetric air flow rate between 5 to 17 L min–1. The highest biomass and lipid concentrations were determined at the higher aeration rate (20 L min–1), which was correlated with the lower tM, the higher hold-up and kLa(CO2)T values. Biomass and lipid production showed an inverse correlation. The highest biomass concentration (750 mg L–1) and the lowest lipid concentration (10 mg L–1) were measured with the star sparger. In contrast, when the lowest biomass concentration was obtained (240 mg L–1), the highest lipid concentration of 196 mg L–1 was measured with the glass sparger. The maximum biomass productivity values were determined at the lower aeration rate and the star sparger, with the minimum power per unit of volume, which could be useful for a cost-effective process.

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Han, Lu, Premkumar Kamalanathan, and Muthanna H. Al-Dahhan. "Gas–liquid mass transfer using advanced optical probe in a mimicked FT slurry bubble column." International Journal of Chemical Reactor Engineering 19, no. 1 (December 25, 2020): 31–42. http://dx.doi.org/10.1515/ijcre-2020-0143.

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Abstract Gas-liquid volumetric liquid-phase mass transfer coefficient (k L a) was studied in a slurry bubble column at the conditions mimicking Fischer–Tropsch synthesis. To avoid the hydrodynamic disturbances due to the gas switching, oxygen enriched air dynamic absorption method was used. Influence of reactor models (CSTR, ADM and RCFD) on the volumetric mass transfer coefficient was investigated. Effect of operating pressure, superficial gas velocity and solids loading were investigated. From the reactor models investigated, it is recommended to use ADM model for k L a study. If the CSTR model is used, applicability of the model should be checked. With increase in the superficial gas velocity and operating pressure, volumetric liquid-phase mass transfer coefficient increases, while it decreases with the solids loading corroborating with the literature.

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47

Márquez, Alejandro Lara, Gabriel Wild, and Noël Midoux. "A review of recent chemical techniques for the determination of the volumetric mass-transfer coefficient kLa in gas—liquid reactors." Chemical Engineering and Processing: Process Intensification 33, no. 4 (September 1994): 247–60. http://dx.doi.org/10.1016/0255-2701(94)01006-4.

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48

Stenberg, O., and N. H. Schöön. "Aspects of the graphical determination of the volumetric mass-transfer coefficient (kLa) in liquid-phase hydrogenation in a slurry reactor." Chemical Engineering Science 40, no. 12 (1985): 2311–19. http://dx.doi.org/10.1016/0009-2509(85)85134-4.

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Karaffa, Levente, Erzsébet Sándor, Erzsébet Fekete, József Kozma, Attila Szentirmai, and István Pócsi. "Stimulation of the cyanide-resistant alternative respiratory pathway by oxygen in Acremonium chrysogenum correlates with the size of the intracellular peroxide pool." Canadian Journal of Microbiology 49, no. 3 (March 1, 2003): 216–20. http://dx.doi.org/10.1139/w03-029.

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The relationship between oxygen input and activity of the cyanide-resistant alternative respiration of submerged cultures of Acremonium crysogenum was investigated. The volumetric oxygen transfer coefficient of the respective cultures correlated positively within almost two ranges of magnitude with the size of the intracellular peroxide pool, which in turn, correlated with the activity of the cyanide-resistant alternative respiratory pathway. Increased aeration also stimulated the glucose uptake rate but had no effect on the total respiration rate or the growth rate. Addition of the lipid peroxyl radical scavenger DL-α-tocopherol to A. chrysogenum cultures decreased the rate of intracellular peroxide production as well as glucose uptake. An increase in the cyanide-resistant fraction of total respiration was observed, while growth and the total respiratory activity remained unchanged. We conclude that intracellular peroxides may stimulate the alternative respiration in A. chrysogenum.Key words: Acremonium chrysogenum, alternative respiration, oxygen, peroxide, Kla.

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Irizar, I., J. A. Zambrano, D. Montoya, M. De Gracia, and R. García. "Online monitoring of OUR, KLa and OTE indicators: practical implementation in full-scale industrial WWTPs." Water Science and Technology 60, no. 2 (July 1, 2009): 459–66. http://dx.doi.org/10.2166/wst.2009.363.

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Based on on/off aeration strategies, this paper describes all the steps involved in the development and implementation of three identification algorithms aimed at monitoring the oxygen uptake rate (OUR), the oxygen mass-transfer coefficient (KLa), and oxygen transfer efficiency (OTE) in aerated biological reactors. Firstly, a detailed explanation of the theoretical background behind every algorithm is given. In addition, practical issues have also been taken into account in order to guarantee the quality of estimations. Finally, the three algorithms have been implemented and validated in a full-scale industrial wastewater treatment plant with satisfactory results. Although short-term noise has been observed in the estimated data (especially at high OURs), the medium and long-term data trajectories have been correctly reproduced.

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Journal articles on the topic 'Oxygen volumetric mass transfer coefficient (kLa)'

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