Monitoring off-gas O2/CO2 to predict nitrification performance in activated sludge processes

Leu, Shao-Yuan; Libra, Judy A.; Stenstrom, Michael K.

doi:10.1016/j.watres.2010.03.022

Cited by 22 publications

(11 citation statements)

References 21 publications

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“…The optimized values of the kinetic parameters determined by nonlinear regression are listed in Table 1. The maximum growth rates (m max ) of the studied strain were 1.20 h -1 , 0.99 h -1 , and 0.62 h -1 for glucose, cellobiose, and xylose, respectively, which were within similar range for other lactic acid producing strains using different substrates [23][24][25][26][27][28]. The m max and K s values for glucose were higher than xylose and cellobiose, implying that glucose is the preferred carbon source of strain QU 25, which was further con rmed by the residual sugars in CSFTR.…”

Section: Batch Fermentationsupporting

confidence: 62%

Dynamic Simulation of Continuous Mixed Sugar Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Wang

Chan

Abdel-Rahman

et al. 2020

Preprint

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Background: The simultaneous and effective conversion of both pentose and hexose in fermentation is a critical and challenging task towards the lignocellulosic economy. This study aims to investigate the feasibility of an innovative co-fermentation process featuring with a cell recycling unit (CF/CR) for mixed sugar utilization. A l-lactic acid producing strain Enterococcus mundtii QU 25, was applied in the continuous fermentation process, and the mixed sugars were utilized at different productivities after the flowing conditions were changed. A numerical platform was constructed with the experiments to optimize the biological process and clarify the cell metabolism through kinetics analysis. The structured model, kinetic parameters, and achievement of the fermentation strategy shall provide new insights towards whole sugar fermentation via real-time monitoring for process control and optimization. Results: Significant carbon catabolite repression in co-fermentation using a glucose/xylose mixture was overcome by replacing glucose with cellobiose, and the ratio of consumed pentose to consumed hexose increased significantly from 0.096 to 0.461 by mass. An outstanding product concentration of 65.2 g·L-1 and productivity of 13.03 g·L-1·h-1 were achieved with 50 g·L-1 cellobiose and 30 g·L-1 xylose at an optimized dilution rate of 0.2 h-1, and the cell retention time gradually increased. Among the total lactic acid production, xylose contributed to more than 34% of the mixed sugars, which was close to the related contents in agricultural residuals. The model successfully simulated the transition of sugar consumption, cell growth, and lactic acid production among the batch, continuous process, and CF/CR systems. Conclusion: Cell retention time played a critical role in balancing pentose and hexose consumption, cell decay, and lactic acid production in the CF/CR process. With increasing cell concentration, consumption of mixed sugars increased with the productivity of the final product; hence, the impact of substrate inhibition was reduced. With the validated parameters, the model showed the highest accuracy simulating the CF/CR process, and significantly longer cell retention times compared to hydraulic retention time were tested.

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Section: Batch Fermentationsupporting

confidence: 62%

Dynamic Simulation of Continuous Mixed Sugar Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Wang

Chan

Abdel-Rahman

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…The optimized values of kinetic parameters determined by nonlinear regression are listed in Table 1. The maximum growth rates (m max ) of the studied strain were 1.20 h -1 , 0.99 h -1 , and 0.62 h -1 for glucose, cellobiose, and xylose, respectively, which were within similar range for other lactic acid producing strains using different substrates [23][24][25][26][27][28]. The higher m max and K s for glucose than xylose and cellobiose implied the preferred carbon source of the strain QU 25, which was further confirmed by the residual sugars in CSFTR.…”

Section: Batch Fermentationsupporting

confidence: 62%

“…The sugar consumption and lactic acid production are cell growth associated [24]. The following ordinary differential equations (ODEs) were derived to quantify the dynamic changes of the reactants and products:…”

Section: Model Developmentmentioning

confidence: 99%

Dynamic Simulation of Continuous Mixed Sugars Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Wang

Chan

Abdel-Rahman

et al. 2020

Preprint

Self Cite

View full text Add to dashboard Cite

Background: Simultaneous and effective conversion of both pentose and hexoses in fermentation is a critical and challenging task toward the lignocellulosic economy. This study aims to investigate the feasibility of an innovative co-fermentation process featured with cell recycle unit (CF/CR) for mixed sugar utilization. A l-lactic acid producing strain Enterococcus mundtii QU 25 was applied in the continuous fermentation process to utilize the mixed sugar at different productivities over the changes of flowing conditions. Structured numerical platform were constructed with the experiments to optimize the biological process and clarify the cell metabolisms through kinetics analysis. The structured model, kinetic parameters, and achievement of the fermentation strategy shall provide new insights towards whole sugar fermentation via real-time monitoring for process control and optimization.Results: Significant carbon catabolite repression of co-fermentation using glucose/xylose mixture was overcome by replacing glucose with cellobiose, of which the consumption ratio of hexose to pentose was improved dramatically from 10.4:1 to 2.17:1. An outstanding product concentration of 65.15 g·L -1 and productivity of 13.03 g·L -1 ·h -1 were achieved with 50 g·L -1 cellobiose and 30 g·L -1 xylose, at an optimized dilution rate of 0.2 h -1 with gradually increased cell retention time. Among the total lactic acid production, xylose contributed to more than 34% of the mixed sugars, which was close to the related contents in agricultural residuals. The model successfully simulated the transition of sugar consumption, cell growth, and lactic acid production among the batch, continuous process, and CF/CR system.Conclusion: Cell retention time played a critical role in balancing pentose and hexose consumption, cell decay, and lactic acid production in the CF/CR process. With the increase of cell concentration, consumption of mixed sugars increased with the productivity of final products, hence the impacts of substrate inhibiting reduced. With the validated parameters, the model showed highest accuracy simulating the CF/CR process, of which significantly longer cell retention times over hydraulic retention time were tested.

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“…NO 2 -+ 0.5O 2 → NO 3 -Conventional biological treatment, like activated sludge (AS), is used to remove nitrogen (Ahn, 2006;Leu et al, 2010). Such systems can remove up to 99% of NH 4 + -N operated under an ammonia loading rate (ALR) of 4 gNH 4 + -N/L·d (Antileo et al, 2002;Campos et al, 2002).…”

Section: Introductionmentioning

confidence: 99%

Effect of the Carbon Source on Nitrifying in an Activated Sludge System Treating Aquaculture Wastewater

Morales¹,

Sanhueza²,

Vidal³

2015

JAS

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The nitrogen in the aquaculture wastewater can have significant effects on receiving water bodies like eutrophication and ammonia toxicity to fish communities. Removing nitrogen by nitrification-denitrification can reduce the potential impact of aquaculture wastewater discharge. Nitrification is affected by different factors including dissolved oxygen, temperature, pH, alkalinity, toxicity, unionized ammonia and substrate concentration. All these parameters affect ammonia-oxidizing and nitrite-oxidizing bacterial activity.The aim of this work is to study the effect of the carbon source on nitrifying bacterial activity in an activated sludge treating aquaculture wastewater.An activated sludge (AS) system was set up and operated continuously for 180 days. The operation was divided into two phases. During Phase I a source of organic carbon (CH 3 COONa) with a C/N level of 2.4 (operation days 1 to 101) was fed into the system, while in Phase II a source of inorganic carbon (NaHCO 3 ) with a C/N level of 16.2 was fed into the system (operation days: 102 to 180).The maximum NH 4 + -N removal efficiency was 49.7% during the Phase I, during which the NO 3 --N and NH 3 + -N concentrations were 37.1 ± 14.0 and 2.9 ± 1.1 mg/L, respectively. In Phase II, the maximum NH 4 + -N removal efficiency was 45% and NO 3 --N and NH 3 + -N effluent concentrations were 2.8 ± 0.3 mg/L and 210 ± 49 mg/L, respectively. Ammonia-and nitrite-oxidation decreased in Phase I from 0.231 ± 0.005 mg NH 4 + /gVSS min to 0.018 ± 0.004 mg NH 4 + -N/gVSS min and in Phase II from 0.049 ± 0.011 mgNO 2 --N/gVSS min to 0.010 ± 0.002 mgNO 2 --N/gVSS min.

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Monitoring off-gas O2/CO2 to predict nitrification performance in activated sludge processes

Cited by 22 publications

References 21 publications

Dynamic Simulation of Continuous Mixed Sugar Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Dynamic Simulation of Continuous Mixed Sugar Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Dynamic Simulation of Continuous Mixed Sugars Fermentation with Increasing Cell Retention Time for Lactic Acid Production using Enterococcus mundtii QU 25

Effect of the Carbon Source on Nitrifying in an Activated Sludge System Treating Aquaculture Wastewater

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