Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9607693 | Process Biochemistry | 2005 | 12 Pages |
Abstract
Mass transfer and kinetics of nitrification using free and alginate gel immobilized Nitrosomonas cells were investigated under no cell growth conditions. A simulated wastewater with industrial strength ammonia content was employed. Under the conditions employed, external diffusion limitations were negligible, but internal mass transfer was found to be very significant. The estimated effective diffusivity of oxygen in alginate gel was around 8.7 à 10â9 m2 sâ1 for assumed first order kinetics at 25 °C. This value is somewhat lower than reported values, and the discrepancy was explained in terms of different conditions and presence of biomass in this study. The activation energy for nitrification with free Nitrosomonas cells was around 73 kJ molâ1 and compared favourably with reported values. However, the Arrhenius plot for nitrification using immobilized cells displayed a break at 20 °C, and this gave rise to two different activation energies. Between 20 and 35 °C, the activation energy was around 56 kJ molâ1, whilst between 10 and 20 °C, the activation energy was around 163 kJ molâ1. This result suggests that different rate limiting steps for nitrification using immobilized cells may apply according to the range of temperatures employed.
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Physical Sciences and Engineering
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Bioengineering
Authors
F. Benyahia, R. Polomarkaki,