Effects of diffusion limitation on immobilized nitrifying microorganisms at low temperatures

Abstract

Activation energies of suspended and immobilized nitrifying bacteria were determined and compared to determine if diffusion limitation results in decreased sensitivity for temperature. The activation energy for the respiration activity of suspended Nitrosomonas europaea and Nitrobacter agilis was found to be 86.4 and 58.4 kJ mol(-1), respectively. The activation energy for oxygen diffusion in the support material, kappa-carrageenan, determined from the effect of temperature on the effective diffusion coefficient (D), was 17.2 kJ mol(-1). Consequently, the apparent actvation energy of diffusion limited cells should be lower. It was indeed shown that due to the effect of diffusion limitation and to temperature effects on the Monod constant K(s), the immobilized-cell activity was less sensitive to temperature. The apparent activation energy for immobilized Ns. europaea was between 28.6 and 94.2 kJ mol(-1) and for immobilized Nb. agilis between 1.4 and 72.9 kJ mol(-1), depending on the oxygen concentration and temperature. (c) 1995 John Wiley & Sons, Inc.

Diffusional Properties of Methanogenic Granular Sludge: 1 H NMR Characterization

“…Figure 1 shows that these aggregates also contain cavities, which can develop because of the high decay rates under thermophilic conditions or during starvation periods (1). In contrast, growth of aggregates at low temperatures (10°C) results in the formation of dense and compact aggregates with a slow diffusional transport (Table 4), as has also been reported for immobilized nitrifying microorganisms (37).…”

Dynamics of artificially immobilizedNitrosomonas europaea: Effect of biomass decay

“…From these results it is concluded that the results of the Wijffels et al, 1994 model in which the separately deterined decay rates are incorporated match slightly better with the experimental data.…”

Cultivation of Marine Sponges

“…The limiting substrate was assumed to be oxygen, and the oxygen concentration was assumed to be saturating (0.2 mol m −3 ). It was assumed that oxygen consumption took place according to zero-order kinetics and that the effective diffusion coefficient in the sponge was 2.05 × 10 −9 m 2 s −1 , which is similar to the one in gel materials we studied earlier (Wijffels et al, 1995).…”