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Appropriate Fe (II) addition significantly enhances anaerobic ammonium oxidation (Anammox) activity through improving the bacterial growth rate.

Liu Y, Ni BJ - Sci Rep (2015)

Bottom Line: This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels.Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d(-1) compared to 0.118 d(-1) at regular Fe (II) level (0.03 mM).The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition.

View Article: PubMed Central - PubMed

Affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.

ABSTRACT
The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d(-1) compared to 0.118 d(-1) at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment.

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The experimentally observed and model-fitted relationship between Fe (II) concentrations and the specific Anammox growth rates using the substrate inhibition kinetics (symbols represent the rate values in batch tests, red line represents the kinetic fitting profile, and black dash represents the predicted 95% confidence bounds during the fitting).
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f2: The experimentally observed and model-fitted relationship between Fe (II) concentrations and the specific Anammox growth rates using the substrate inhibition kinetics (symbols represent the rate values in batch tests, red line represents the kinetic fitting profile, and black dash represents the predicted 95% confidence bounds during the fitting).

Mentions: The batch test results clearly showed that appropriate Fe (II) addition increased the specific Anammox growth rate but over-dosing Fe (II) slightly decreased the rate (Figure 1). Although Fe (II) is the essential substrate element that required for culturing Anammox sludge, it has been also reported that Fe (II) at a high concentration could likely induce biomass destruction3132. Therefore, high concentrations of Fe (II) might lead to a slight inhibition on Anammox activity, as observed in this study. Figure 2 summarizes the estimated specific Anammox growth rates (μAN) in all of the batch tests at each of the corresponding Fe (II) concentrations. The dependence of μAN on the Fe (II) concentration could be well described using the typical substrate inhibition kinetics33 with R2 value of 0.98 as shown in Figure 2 and following equation.where 0.4798 d−1 is the maximum growth rate of Anammox bacteria under the studied conditions, 0.08114 mM is half-saturation concentration constant and 0.1001 mM is inhibition constant. The predicted 95% confidence bounds included all the data points, further indicating that the effect of Fe (II) on Anammox growth rates could be well described by substrate inhibition kinetics (red line, Figure 2), with the best Fe (II) dosing concentration at 0.09 mM under the studied conditions.


Appropriate Fe (II) addition significantly enhances anaerobic ammonium oxidation (Anammox) activity through improving the bacterial growth rate.

Liu Y, Ni BJ - Sci Rep (2015)

The experimentally observed and model-fitted relationship between Fe (II) concentrations and the specific Anammox growth rates using the substrate inhibition kinetics (symbols represent the rate values in batch tests, red line represents the kinetic fitting profile, and black dash represents the predicted 95% confidence bounds during the fitting).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4316192&req=5

f2: The experimentally observed and model-fitted relationship between Fe (II) concentrations and the specific Anammox growth rates using the substrate inhibition kinetics (symbols represent the rate values in batch tests, red line represents the kinetic fitting profile, and black dash represents the predicted 95% confidence bounds during the fitting).
Mentions: The batch test results clearly showed that appropriate Fe (II) addition increased the specific Anammox growth rate but over-dosing Fe (II) slightly decreased the rate (Figure 1). Although Fe (II) is the essential substrate element that required for culturing Anammox sludge, it has been also reported that Fe (II) at a high concentration could likely induce biomass destruction3132. Therefore, high concentrations of Fe (II) might lead to a slight inhibition on Anammox activity, as observed in this study. Figure 2 summarizes the estimated specific Anammox growth rates (μAN) in all of the batch tests at each of the corresponding Fe (II) concentrations. The dependence of μAN on the Fe (II) concentration could be well described using the typical substrate inhibition kinetics33 with R2 value of 0.98 as shown in Figure 2 and following equation.where 0.4798 d−1 is the maximum growth rate of Anammox bacteria under the studied conditions, 0.08114 mM is half-saturation concentration constant and 0.1001 mM is inhibition constant. The predicted 95% confidence bounds included all the data points, further indicating that the effect of Fe (II) on Anammox growth rates could be well described by substrate inhibition kinetics (red line, Figure 2), with the best Fe (II) dosing concentration at 0.09 mM under the studied conditions.

Bottom Line: This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels.Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d(-1) compared to 0.118 d(-1) at regular Fe (II) level (0.03 mM).The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition.

View Article: PubMed Central - PubMed

Affiliation: Advanced Water Management Centre, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.

ABSTRACT
The application of anaerobic ammonium oxidation (Anammox) process is often limited by the slow growth rate of Anammox bacteria. As the essential substrate element that required for culturing Anammox sludge, Fe (II) is expected to affect Anammox bacterial growth. This work systematically studied the effects of Fe (II) addition on Anammox activity based on the kinetic analysis of specific growth rate using data from batch tests with an enriched Anammox sludge at different dosing levels. Results clearly demonstrated that appropriate Fe (II) dosing (i.e., 0.09 mM) significantly enhanced the specific Anammox growth rate up to 0.172 d(-1) compared to 0.118 d(-1) at regular Fe (II) level (0.03 mM). The relationship between Fe (II) concentration and specific Anammox growth rate was found to be well described by typical substrate inhibition kinetics, which was integrated into currently well-established Anammox model to describe the enhanced Anammox growth with Fe (II) addition. The validity of the integrated Anammox model was verified using long-term experimental data from three independent Anammox reactors with different Fe (II) dosing levels. This Fe (II)-based approach could be potentially implemented to enhance the process rate for possible mainstream application of Anammox technology, in order for an energy autarchic wastewater treatment.

Show MeSH