Trickle-bed Bioreactor Research Articles

Continuous Fermentation of Worcestershire Sauce by Trickle Bed Bioreactor Using Comb‐Shaped Ceramic Carriers

ABSTRACTA two‐step fermentation process using Saccharomyces cerevisiae OC‐2 (wine yeast) was studied. The first step, to multiply and immobilize yeast cells, was carried out by batch method (7 days) in a trickle bed bioreac‐tor. In a second step, the substrate was continuously fermented by immobilized and free yeast cells in the same bioreactor. Continuous fermentation resulted in retention of 3% (W/V) of ethanol, 50 mg/L of isoamyl alcohol and 6 mg/L of β‐phenethyl alcohol (the major aromatic components of fermented Worcestershire sauce). Maximum ethanol productivity was retained at 4.1–4.2 g/L/hr under continuous operation with immobilized yeasts, 3.2‐fold higher than with the batch system.

Degradation of toluene/heptane mixtures in a trickling-bed bioreactor

Degradation of toluene/heptane mixtures in a trickling-bed bioreactor

Production of Worcestershire Sauce by a Trickle Bed Bioreactor Using Comb-Shaped Ceramics Carriers

The purpose of this study is to prepare Worcestershire sauce with higher levels of ethanol and aromatic components by a trickle bed bioreactor. Ethanol productivity in a trickle bed bioreactor was measured with changing circulation rates from 40 to 280 ml/min with a fixed aeration rate (200 ml/min) at 28°C. Compared with the lower circulation rate (40 ml/min), at 210 ml/min of circulation rate or higher, ethanol productivity increased 10.3-fold at 41 h of fermentation.

Modelling of biodegradation processes in trickle-bed bioreactors

This paper deals with the mathematical modelling of a biological process to remove organic compounds from industrial waste gas. Modelling results will be compared with experimental data from measurements utilizing a laboratory-scale trickle-bed bioreactor. In such an apparatus, the biodegradation of the organic pollutants takes place via aerobic oxidation in a biofilm, which is immobilized on a packing material. Two organic compounds were chosen as model pollutants, i.e. ethanol and polyalkylated benzenes. In addition, data from the literature of a third compound, dichloromethane, will be analysed. The mathematical model used in this work is based on the stationary differential mass balances along the reactor height together with the corresponding reaction terms. The experiments with ethanol reveal that over a large range of gas inlet concentrations, the rate limiting factor of the degradation process is oxygen limitation. The reason for this is the small partition coefficient of ethanol resulting in large liquid concentrations. Thus, the pollutant is mineralized at a relatively high rate until dissolved oxygen inside the biofilm is depleted. In these cases, model calculations with a zeroth-order reaction term describe the experimental data well. The experiments with polyalkylated benzenes reveal that substrate limitation occurs within the relevant range of gas inlet concentrations. The reason for this is the large partition coefficient resulting in small liquid concentrations. Thus, first-order reaction applies. Again, a rather good agreement of model and experiment is achieved. The analysis of the data of dichloromethane yields kinetic data within the transition regime of first-order and zeroth-order reaction rates. Thus, no significant difference is observed with the model calculations using either reaction order. The mathematical model presented can serve as a basis for proper design, up-scaling, and control strategies of trickle-bed bioreactors.

Modelling of biodegradation processes in trickle-bed bioreactors

Modelling of biodegradation processes in trickle-bed bioreactors

Design and performance of a trickle-bed bioreactor with immobilized hybridoma cells.

A trickle-bed system employing inert matrices of vermiculite or polyurethane foam packed in the downcomer section of a split-flow air-lift reactor has been developed for hybridoma culture to enhance antibody productivity. This quiescent condition favoured occlusion and allowed the cells to achieve densities twelve fold greater (12.8 x 10(6) cells/ml reactor for polyurethane foam) than in free cell suspension. The reactor was operated in a cyclic batch mode whereby defined volumes of medium were periodically withdrawn and replaced with equal volumes of fresh medium. The pH of the medium was used as the indicator of the feeding schedule. Glucose, lactate and ammonia concentrations reached a stationary value after 5 days. With vermiculite packing, a monoclonal antibody (MAb) concentration of 2.4 mg/l was achieved after 12 days. The MAb concentration declined then increased to a value of 1.8 mg/l. In the polyurethane foam average monoclonal antibody (MAb) concentrations reached a stationary value of 1.1 mg/l in the first 20 days and increased to a new stationary state value of 2.1 mg/l for the remainder of the production. MAb productivity in the trickle-bed reactor was 0.3 mg/l.d (polyurethane foam) and 0.18 mg/l.d (vermiculite) in comparison to 0.12 mg/l.d for free cell suspension. This trickle-bed system seems to be an attractive way of increasing MAb productivity in culture.

Purification of exhaust air containing organic pollutants in a trickle-bed bioreactor

This paper reports experiments on the purification of exhaust air containing organic pollutants by a new biological process using a trickle-bed reactor. Pollutant-specific microorganisms in high concentration were fixed to a suitable bed. The absorption and conversion of propionaldehyde as a model pollutant was measured by systematic variation of the gas and liquid flow rates in the reaction system. At a space velocity of 1000 h(-1), it was possible to achieve conversion rates of between 68 and 96%, depending on the trickling density. The degradation capacity of the biological trickle bed is over 500 g propionaldehyde/m(3) of reactor per hour. By using a tube bundle (honeycomb tube), it was possible to ensure continuous operation of the reactor with reduced conversion and pressure loss.

Performance of trickle-bed bioreactors for converting synthesis gas to methane

Carbon monoxide, H2, and CO2 in synthesis gas can be converted to CH4 by employing a triculture of Rhodospirillum rubrum, Methanosarcina barkeri, and Methanobacterium formicicum. Trickle-bed reactors have been found to be effective for this conversion because of their high mass-transfer coefficients. This paper compares results obtained for the conversion of synthesis gas to CH4 in 5-cm- and 16.5-cm-diameter trickle-bed reactors. Mass-transfer and scale-up parameters are defined, and light requirements for R. rubrum are considered in bioreactor design.

Dichloromethane removal from waste gases with a trickle-bed bioreactor

A 66 dm3 trickle-bed bioreactor was constructed to assess the possibilities of eliminating dichloromethane from industrial waste gases. The trickle-bed bioreactor was filled with a randomly-stacked polypropylene packing material over which a liquid phase was circulated. The pH of the circulating liquid was externally controlled at a value of 7 and the temperature was maintained at 25 °C. The packing material was very quickly covered by a dichloromethane-degrading biofilm which thrived on the dichloromethane supplied via the gas phase. The biological system was very stable and not sensitive to fluctuations in the dichloromethane supply. Removal of dichloromethane from synthetic waste gas was possible down to concentrations well below the maximal allowable concentration of 150mg/m3 required by West-German law for gaseous emissions. At higher dichloromethane concentrations specific dichloromethane degradation rates of 200 g h−1 m−3 were possible. At very low inlet concentrations, dichloromethane elimination was completely mass transfer limited.