Nitrification Studies at Non-limiting Substrate Concentrations

Prosser, James I.; Gray, T. R. G.

doi:10.1099/00221287-102-1-111

Cited by 13 publications

(2 citation statements)

References 19 publications

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“…The ratio reported by Prosser and Gray [35] is 1/100, but the activity of the Nitrobacter sp. they used is 10 times lower than the mean activities reported by Prosser [36].…”

Section: Biomass Distribution In Steady-statementioning

confidence: 93%

“…This can be compared with the observation of Cox et al [17] who found that less than 20% of their column was active in their non-limiting working conditions. The development of Nitrosomonas in the lower part of a ®xed bed column packed with glass bead is reported too by Prosser and Gray [35], together with a rather homogenous distribution of Nitrobacter in the same column.…”

Section: Biomass Distribution In Steady-statementioning

confidence: 94%

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Dynamic model of a nitrifying fixed bed column: Simulation of the biomass distribution of Nitrosomonas and Nitrobacter and of transient behaviour of the column

Poughon

Dussap

Gros

1999

Bioprocess Engineering

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A dynamic model for a ®xed bed nitrifying column with recirculation of the liquid and gas phases was developed. Liquid RTD experiments demonstrated that the liquid phase was perfectly mixed inside the column. Heterogeneity of biomass distribution on the solid phase (beads) was represented by an N-tanks in series model, and a back-mixing term was set to account for the wellmixed liquid phase throughout the column. In autotrophic conditions, competition for oxygen is the cause of the spatial segregation of the two species. Nitrosomonas is concentrated on beads at the bottom of the bed whereas Nitrobacter is more widely distributed. This is consistent with biomass distribution results reported by Cox et al.[17] in a nitrifying ®xed bed column. Nitri®cation takes place at the bottom of the column, always in oxygen gasliquid mass transfer limiting conditions. Nevertheless, considering the whole process, nitri®cation is complete (>98% of NH 3 oxidised) and there is no oxygen limitation (the outlet dissolved oxygen concentration is not limiting). The dynamic behaviour of the column, in conditions set up to avoid bio®lm diffusion limitation, was simulated for different NH 3 -load variations and oxygen shutdowns. The simulated behaviour of the column can be compared to results reported by Bazin et al. [16]. This con®rms that the output transient nitrite peaks are higher when changes in the process conditions produce a rearrangement of biomass distribution in the ®xed bed.

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“…The ratio reported by Prosser and Gray [35] is 1/100, but the activity of the Nitrobacter sp. they used is 10 times lower than the mean activities reported by Prosser [36].…”

Section: Biomass Distribution In Steady-statementioning

confidence: 93%

Section: Biomass Distribution In Steady-statementioning

confidence: 94%

Dynamic model of a nitrifying fixed bed column: Simulation of the biomass distribution of Nitrosomonas and Nitrobacter and of transient behaviour of the column

Poughon

Dussap

Gros

1999

Bioprocess Engineering

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The dynamics of anaerobic phenol biodegradation in lower greensand

Rees¹,

King²

1981

J. Chem. Technol. Biotechnol.

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The anaerobic biodegradation of phenol in the unsaturated zone beneath landfill sites has been simulated by percolating an artificial landfill leachate containing phenol through columns of disturbed Lower Greensand. The columns were inoculated with microbes from a laboratory-scale landfill simulator. Phenol degradation was observed at concentrations up to 8.2 g dm-3 but decomposition was increasingly inhibited above 3.0 g dm+. Maximum rates of decomposition were observed at concentrations between 1.5 and 3.0 g dm-3. The Vma, value at a flow rate of 0.5 cm3 h-1 was 1.05 g dm-3h-1 and the K m value was 450 mg phenol dm-3. Zero-(ro) and first-order ( r l ) rate constants increased with increasing flow rate. The data are used to calculate the rates of phenol degradation which might be obtained in real landfill.

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The dynamics of aerobic phenol biodegradation in lower greensand

Rees¹,

King²

1980

J. Chem. Technol. Biotechnol.

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The dynamics of phenol degradation in sedimentary rocks was examined by percolating phenol solutions, with no added nutrients, through columns of disturbed Lower Greensand. Phenol degradation was achieved at concentrations up to 16.7 g dm−3. Inhibition was evident at higher concentrations. Sterilisation of Lower Greensand by moist heat or irradiation completely destroyed its ability to degrade phenol. Non‐growing bacterial cells attached to sand and clay particles were responsible for phenol degradation. Zero‐ and first‐order rate values for phenol degradation increased with increasing flowrate. First‐order kinetics operated with respect to substrate concentration. At flowrates of 1 cm3 h−1 (0.063 cm h−1) the reaction approached zero‐order at phenol concentration above 9.2 g dm−3 but at flowrates of 3 cm3 h−1 (0.19 cm h−1) increasing the phenol input concentration above 9.7 g dm−3 resulted in strong inhibition of activity. The results are explained in terms of phenol degradation being limited by the diffusion of phenol across a stagnant liquid film surrounding the microbes.

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Nitrification Studies at Non-limiting Substrate Concentrations

Cited by 13 publications

References 19 publications

Dynamic model of a nitrifying fixed bed column: Simulation of the biomass distribution of Nitrosomonas and Nitrobacter and of transient behaviour of the column

Dynamic model of a nitrifying fixed bed column: Simulation of the biomass distribution of Nitrosomonas and Nitrobacter and of transient behaviour of the column

The dynamics of anaerobic phenol biodegradation in lower greensand

The dynamics of aerobic phenol biodegradation in lower greensand

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