Recent trends in membrane bioreactors

Use of a membrane within a bioreactor (MBR), either microbial or enzymatic, is a technology that has existed for 30 years to increase process productivity and/or facilitate the recovery and the purification of biomolecules. Currently, this technology is attracting increasing interest in speeding up the process and in better sustainability. In this work, we present the current status of MBR technologies. Fundamental aspects and process design are outlined and emerging applications are identified in both aspects of engineering, i.e., enzymatic and microorganism (bacteria, animal cells, and microalgae), including microscale aspects and wastewater treatment. Comparison of this integrated technology with classical batch or continuous bioreactors is made to highlight the performance of MBRs and identify factors limiting their performance and the different possibilities for their optimization

Adsorptive removal of polyphenols from an alfalfa white proteins concentrate: Adsorbent screening, adsorption kinetics and equilibrium study

The objective of this work was to examine the effectiveness of adsorption for the removal of polyphenols from an alfalfa white protein concentrate to produce a protein purified fraction. Six commercial macro porous resins were tested for their polyphenols adsorption characteristics. The screening results showed that the adsorbent HP20 and the anion-exchange resin AER1 had the best adsorption characteristics with adsorption capacities of 54.62 mg/g and 48.18 mg/g, respectively. The effect of pH, contact time and adsorption isotherms were successively investigated on the two preselected resins. The process kinetics was evaluated by the pseudo-first-order, the pseudo-second-order, Elovich, intra-particle diffusion and the modified pseudo-first-order models. Batch kinetic data have been well described by the pseudo second order model. Meantime, the adsorption process close equilibrium was governed by intra-particle diffusion. The adsorption data were fitted well with the Langmuir isotherm model. It was found that the process is favourable. These results will be used in future studies for the design of column adsorption systems for the purification of the alfalfa protein concentrate and the recovery of phenolic compounds contained in the latter

Pharmacokinetics of tacrolimus (FK506) in paediatric liver transplant recipients.

The pharmacokinetics of intravenous and oral tacrolimus was assessed in paediatric liver transplant patients at two centers in Europe. Sixteen patients, age 0.7 to 13 years, participated in the study; 12 patients were evaluable for intravenous pharmacokinetics, and 16 for oral. Intravenous tacrolimus was given as a continuous 24 h infusion (mean 0.037+/-0.013 mg/kg/day), and oral tacrolimus was given in 2 doses per day (mean 0.152+/-0.015 mg/kg). Whole blood samples for the intravenous pharmacokinetic profile were taken before initiation of the first infusion, 4, 8, 12 and 24 h post-infusion, and every 24 h thereafter until intravenous administration was discontinued. During the 12 h wash-out period between intravenous and oral administration, samples were taken every 3 h. Samples for the oral pharmacokinetic profile were taken immediately before the first oral dose and 0.5, 0.75, 1, 2, 2.5, 3, 4, 6, 8, 10 and 12 h post-administration. Non-compartmental procedures were used to characterise the pharmacokinetic parameters. Mean estimates for clearance and terminal half-life were 2.3+/-1.2 ml/min/kg and 11.5+/-3.8 h, respectively, following intravenous tacrolimus. The mean bioavailability of oral tacrolimus was 25+/-20%. A strong correlation was observed between AUC and trough whole blood levels of tacrolimus (r=0.90). The clearance was approximately 2-fold higher than that previously observed in adults; this could explain the higher dosage requirements in children