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Modelling the combined inhibition and time-dependent inactivation effects of toluene on ammonia and nitrite oxidation using a nitrifying sludge

Paper ID Volume ID Publish Year Pages File Format Full-Text
3253 161 2013 8 PDF Available
Title
Modelling the combined inhibition and time-dependent inactivation effects of toluene on ammonia and nitrite oxidation using a nitrifying sludge
Abstract

•Modelling of combined inhibition and inactivation effects of toluene on ammonia and nitrite oxidation in nitrifying cultures.•Time-varying nature of the inactivation factor to predict current nitrification depending on past experimental conditions where cells were exposed to toluene.•Reliable predictions under a wide range of toluene initial concentrations with additional inactivation assays.•Predictive tool to improve nitrification processes where cells are repeatedly or sequentially exposed to hydrocarbons, such as SBR systems.

The simultaneous oxidation of ammonia, nitrite and toluene using a nitrifying sludge was evaluated and modelled. The experimental data showed that the sole instantaneous inhibition effect due to the presence of toluene was not sufficient to explain the severe decrease in the nitrification activity during the cultures. In addition, prior cell exposure to toluene provoked an important – even complete – inactivation of the nitrifying process. The main contribution was thus to design and integrate an adjustment function in the reaction kinetics to account for the cell inactivation mechanism that occurs during an ongoing culture but is initiated during previous cell exposure to toluene; the use of an adjustment function was a requirement indicated by a previous study using the same nitrifying sludge but in presence of benzene. This inactivation factor varies according to a first-order kinetic model that is time-dependent and enhances the dynamic characteristics of the modelling approach. The model was validated by batch experiments with variable initial toluene concentrations (0 to 20 mg C L−1) and additional inactivation batch assays, where cells were first exposed to 0 to 50 mg of toluene C L−1, washed and then reused in a culture medium without toluene. Changes observed in the ammonium, nitrite, nitrate and toluene concentrations agreed well between the model and experimental data with a single set of kinetic parameters in which confidence intervals and sensitivity were also analysed. The proposed model may be used as a predictive tool to avoid critical conditions for nitrification processes where cells are repeatedly or sequentially exposed to hydrocarbons, such as in a SBR system.

Keywords
Nitrification; Toluene; Inhibition; Inactivation; Modelling
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Modelling the combined inhibition and time-dependent inactivation effects of toluene on ammonia and nitrite oxidation using a nitrifying sludge
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Publisher
Database: Elsevier - ScienceDirect
Journal: Biochemical Engineering Journal - Volume 80, 15 November 2013, Pages 37–44
Authors
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Subjects
Physical Sciences and Engineering Chemical Engineering Bioengineering
Get Full-Text Now
Don't Miss Today's Special Offer
Price was $35.95
You save - $31
Price after discount Only $4.95
100% Money Back Guarantee
Full-text PDF Download
Online Support
Any Questions? feel free to contact us