Effect of Osmotic Pressure on Whey Protein Concentration in Forward Osmosis

Forward osmosis (FO) is an emerging process to dewater whey streams energy efficiently. The driving force for the process is the concentration gradient between the feed (FS) and the concentrated draw (DS) solution. Here we investigate not only the effect of the DS concentration on the performance, but also that of the FS is varied to maintain equal driving force at different absolute concentrations. Experiments with clean water as feed reveal a flux increase at higher osmotic pressure. When high product purities and thus low reverse salt fluxes are required, operation at lower DS concentrations is preferred. Whey as FS induces severe initial flux decline due to instantaneous protein fouling of the membrane. This is mostly due to reversible fouling, and to a smaller extent to irreversible fouling. Concentration factors in the range of 1.2–1.3 are obtained. When 0.5 M NaCl is added to whey as FS, clearly lower fluxes are obtained due to more severe concentration polarization. Multiple runs over longer times show though that irreversible fouling is fully suppressed due to salting in/out effects and flux decline is the result of reversible fouling only

Development of Polydopamine Forward Osmosis Membranes with Low Reverse Salt Flux

Application of forward osmosis (FO) is limited due to membrane fouling and, most importantly, high reverse salt fluxes that deteriorate the concentrated product. Polydopamine (PDA) is a widely used, easily applicable, hydrophilic, adhesive antifouling coating. Among the coating parameters, surprisingly, the effect of PDA coating temperature on the membrane properties has not been well studied. Polyethersulfone (PES) 30 kDa ultrafiltration membranes were PDA-coated with varying dopamine concentrations (0.5-3 g/L) and coating temperatures (4-55 °C). The quality of the applied coating has been determined by surface properties, water permeability and reverse salt flux using a 1.2 M MgSO4 draw solution. The coating thickness increased both with the dopamine concentration and coating temperature, the latter having a remarkably stronger effect resulting in a higher PDA deposition speed and smaller PDA aggregates. In dead‑end stirred cell, the membranes coated at 55 °C with 2.0 g/L dopamine showed NaCl and MgSO4 retentions of 41% and 93%, respectively. In crossflow FO, a low reverse MgSO4 flux (0.34 g/m2·h) was found making a very low specific reverse salt flux (Js/Jw) of 0.08 g/L, which outperformed the commercial CTA FO membranes, showing the strong benefit of high temperature PDA-coated PES membranes to assure high quality products

Apple Juice, Manure and Whey Concentration with Forward Osmosis Using Electrospun Supported Thin-Film Composite Membranes

Forward osmosis (FO), using the osmotic pressure difference over a membrane to remove water, can treat highly foul streams and can reach high concentration factors. In this work, electrospun TFC membranes with a very porous open support (porosity: 82.3%; mean flow pore size: 2.9 µm), a dense PA-separating layer (thickness: 0.63 µm) covalently attached to the support and, at 0.29 g/L, having a very low specific reverse salt flux (4 to 12 times lower than commercial membranes) are developed, and their FO performance for the concentration of apple juice, manure and whey is evaluated. Apple juice is a low-fouling feed. Manure concentration fouls the membrane, but this results in only a small decrease in overall water flux. Whey concentration results in instantaneous, very severe fouling and flux decline (especially at high DS concentrations) due to protein salting-out effects in the boundary layer of the membrane, causing a high drag force resulting in lower water flux. For all streams, concentration factors of approximately two can be obtained, which is realistic for industrial applications

Effect of osmotic pressure on whey protein concentration in forward osmosis

Forward osmosis (FO) is an emerging process to dewater whey streams energy efficiently. The driving force for the process is the concentration gradient between the feed (FS) and the concentrated draw (DS) solution. Here we investigate not only the effect of the DS concentration on the performance, but also that of the FS is varied to maintain equal driving force at different absolute concentrations. Experiments with clean water as feed reveal a flux increase at higher osmotic pressure. When high product purities and thus low reverse salt fluxes are required, operation at lower DS concentrations is preferred. Whey as FS induces severe initial flux decline due to instantaneous protein fouling of the membrane. This is mostly due to reversible fouling, and to a smaller extent to irreversible fouling. Concentration factors in the range of 1.2–1.3 are obtained. When 0.5 M NaCl is added to whey as FS, clearly lower fluxes are obtained due to more severe concentration polarization. Multiple runs over longer times show though that irreversible fouling is fully suppressed due to salting in/out effects and flux decline is the result of reversible fouling only

Effects of somatostatin analogues and vitamin C on bacterial translocation in an experimental intestinal obstruction model of rats

WOS: 000087848300006PubMed ID: 10933113The passage of viable endogenous bacteria and their products across the intact intestinal mucosal barrier, disseminating to the mesenteric lymph nodes, peritoneal cavity, spleen, liver, and circulation, is defined as bacterial translocation. Intestinal obstruction induces bacterial translocation due to mucosal disruption, motility dysfunction, and increased intestinal volume, leading to bacterial overgrowth. In a rat model of intestinal obstruction, the effects of both high-dose vitamin C (350 mu g/kg), an antioxidant agent known to have a cytoprotective effect in ischemia-reperfusion injury, and somatostatin (20 mu g/kg), a gastrointestinal antisecretory agent, in preventing bacterial translocation were studied. Both intestinal and liver samples from the rats was observed, and it was found that the rate of bacterial translocation was 100% in the control group, and only 43% for the rats who were given intraperitoneal vitamin C and somatostatin. The difference was statistically significant. In conclusion, we are convinced that vitamin C and somatostatin analogues may have protective effects against bacterial translocation in mechanical bowel obstruction

A bizarre presentation of pancreatitis with Bryant's sign

WOS: 000345023700021PubMed ID: 2541762

Determination of optimal operation time for the management of acute cholecystitis: a clinical trial

Abstract Introduction: Although all studies have reported that laparoscopic cholecystectomy (LC) is a safe and effective treatment for acute cholecystitis, the optimal timing for the procedure is still the subject of some debate. Aim: This retrospective analysis of a prospective database was aimed at comparing early with delayed LC for acute cholecystitis. Material and methods: The LC was performed in 165 patients, of whom 83 were operated within 72 h of admission (group 1) and 82 patients after 72 h (group 2) with acute cholecystitis between January 2012 and August 2013. All data were collected prospectively and both groups compared in terms of age, sex, fever, white blood count count, ultrasound findings, operation time, conversion to open surgery, complications and mean hospital stay. Results: The study included 165 patients, 53 men and 112 women, who had median age 54 (20-85) years. The overall conversion rate was 27.9%. There was no significant difference in conversion rates (21% vs. 34%) between groups (p = 0.08). The operation time (116 min vs. 102 min, p = 0.02) was significantly increased in group 1. The complication rates (9% vs. 18%, p = 0.03) and total hospital stay (3.8 days vs. 7.9 days, p = 0.001) were significantly reduced in group 1. Conclusions: Early LC within 72 h of admission reduces complications and hospital stay and is the preferred approach for acute cholecystitis