George Hamer

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The relationship between specific growth rate (mu) and steady-state glucose concentration was investigated for Escherichia coli ML30 in carbon-limited chemostat culture. This was made possible by the development of a method for measuring reducing sugars in culture media in the microgram.1-1-range. Cells initially cultivated in batch culture at high glucose(More)
The utilization of mixtures of methanol (C(1)) and glucose (C(6)) of different composition by the methylotrophic yeast Hansenula polymorpha was studied in carbon-limited chemostat culture. For all mixtures tested a similar utilization pattern was observed: At low dilution rates both carbon sources were utilized simultaneously, but at high dilution rates the(More)
An novel diffusion reaction model for the determination of both the steady-state and transient-state behavior of biofilters for waste air biotreatment is developed and discussed. The model considers the reactor to comprise finite sections, for each of which transient mass balances are established and solved by digital simulation. The elimination of methyl(More)
In the work reported here, selected aspects of the dynamic behavior of biofilters for waste air treatment have been investigated. Emphasis was placed on transient state elimination of mixtures of methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) vapors and on explanation of the observed phenomena. The initial startup, the response of the biofilter(More)
Escherichia coli fed-batch cultivations at 22 m3 scale were compared to corresponding laboratory scale processes and cultivations using a scale-down reactor furnished with a high-glucose concentration zone to mimic the conditions in a feed zone of the large bioreactor. Formate accumulated in the large reactor, indicating the existence of oxygen limitation(More)
Experimental evaluation of a diffusion reaction model (part 1) for the determination of both steadyand transient-state behavior of biofilters for waste air biotreatment is presented. The model, applied to the aerobic biodegradation of methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK) vapors from air as single and as mixed pollutants, proved(More)
Methanotrophic biodegradation using the membrane-aerated biofilm reactor (MABR) is a technology offering several advantages over both conventional biofilm reactors and suspended-cell processes. In this study the oxidation efficiency of a methanotrophic biofilm in a 1.5 litre MABR was investigated. Measurements of oxygen and methane uptake rates together(More)
In Part l, the process utility of a thermotolerant methylotrophic bacterium is evaluated in chemostat culture under conditions where methanol, methanol/formaldehyde mixtures and dual methanol/ammonia limitation occurred. The results show that the bacterium studied was nonfastideous under steady-state operation, in contrast to results obtained in batch(More)
We compared three unstructured mathematical models, the master reaction, the square root, and the damage/repair models, for describing the relationship between temperature and the specific growth rates of bacteria. The models were evaluated on the basis of several criteria: applicability, ease of use, simple interpretation of model parameters, problem-free(More)