Biomedical subjects

R Eric Berson

Publications and source records attributed to R Eric Berson.

5 recordsLinked to original sources

PubMed2006

Reintroduced solids increase inhibitor levels in a pretreated corn stover hydrolysate.

Following detoxification of the liquid hydrolysate produced in a corn stover pretreatment process, inhibitor levels are seen to increase with the re-addition of solids for the ensuing hydrolysis and fermentation processes. The solids that were separated from the slurry before detoxification of the liquor contain approx 60% (w/w) moisture, and contamination occurs owing to the diffusion of inhibitors from the moisture entrained in the porous structure of the corn stover solids into the bulk fluid. This evidence suggests the need for additional separation and detoxification steps to purge residual inhibitors entrained in the moisture in the solids. An overliming process to remove furans from the hydrolysate failed to reduce total organic acids concentration, so acids were removed by treatment with an activated carbon powder. Smaller carbon doses proved more efficient in removing organic acids in terms of grams of acid removed per gram of carbon powder. Sugar adsorption by the activated carbon powder was minimal.

Charcoal↗

PubMed2006

Modeling of a continuous pretreatment reactor using computational fluid dynamics.

Computational fluid dynamic simulations are employed to predict flow characteristics in a continuous auger driven reactor designed for the dilute acid pretreatment of biomass. Slurry containing a high concentration of biomass solids exhibits a high viscosity, which poses unique mixing issues within the reactor. The viscosity increases significantly with a small increase in solids concentration and also varies with temperature. A well-mixed slurry is desirable to evenly distribute acid on biomass, prevent buildup on the walls of the reactor, and provides an uniform final product. Simulations provide flow patterns obtained over a wide range of viscosities and pressure distributions, which may affect reaction rates. Results provide a tool for analyzing sources of inconsistencies in product quality and insight into future design and operating parameters.

Bioreactors↗

PubMed2005

Detoxification of actual pretreated corn stover hydrolysate using activated carbon powder.

A technique for the removal of acetic acid from an actual pretreated corn stover hydrolysate was investigated. A powdered form of activated carbon previously shown to be effective in the removal of acetic acid from a synthetic hydrolysate was utilized. The method proved to be effective at lowering acetic acid levels while exhibiting minimal adsorption of the desired sugars from the hydrolysate, although at a lower efficiency in the actual hydrolysate than in the synthetic hydrolysate. Results are obtained for temperatures between 25 and 35 degrees C and agitation rates between 150 and 350 rpm in shake flasks. Adsorption isotherm and kinetic rate data are presented. Temperature differences over this range did not have an effect on adsorption characteristics. Five stages of detoxification were necessary to lower acetic acid concentration to the maximum 2 g/L desired for fermentation.

Acetic Acid↗

PubMed2005

Use of computational fluid dynamics simulations for design of a pretreatment screw conveyor reactor.

Computational fluid dynamics simulations were employed to compare performance of various designs of a pretreatment screw conveyor reactor. The reactor consisted of a vertical screw used to create cross flow between the upward conveying solids and the downward flow of acid. Simulations were performed with the original screw design and a modified design in which the upper flights of the screw were removed. Results of the simulations show visually that the modified design provided favorable plug flow behavior within the reactor. Pressure drop across the length of the reactor without the upper screws in place was predicted by the simulations to be 5 vs 40 kPa for the original design.

Acids↗

PubMedDate not supplied

Enhanced mixing and mass transfer in a recirculation loop results in high cell densities in a roller bottle reactor.

A recirculation loop added to a large-scale roller bottle reactor resulted in high cell densities as compared to standard roller bottles. Four different mammalian cell lines reached an average maximum density equal to 5.4 x 10(6) cells /mL (sigma = 0.263), which was between 2.13 and 2.95 times greater than the densities in roller bottles without recirculation using the same cell lines. The high densities were maintained over long durations (>25 days) while the reactor operated with continuous perfusion. The increased densities are attributed to enhanced liquid mixing and oxygen transfer that occur as a result of the recirculation loop. Models were developed that describe axial liquid flow and oxygen transfer in both the sample loop and the reactor growth chamber. Axial dispersion and oxygen transfer coefficients are presented for a variety of operating conditions. The increased oxygen transfer characteristics of the reactor allow for easy scale-up of roller bottle cultures by operating at larger volumes with greater liquid depths than conventional roller bottles permit. The surface-area-to-volume ratio in the tests performed was 0.206 versus 1.16 cm(-1) in a standard roller bottle.

Animals↗