Sugar Syrup Concentration Using Reverse Osmosis Membranes

In sugar manufacturing industries, initially dilute syrup is obtained from the cane sugar or beetroot, which should be concentrated. In many factories, sugar syrup concentration is carried out using evaporation. This process has two main problems. Firstly, it consumes a huge amount of energy due to high latent heat of water and secondly, heating may decompose the sugar molecules resulting in low‐quality and dark‐colored sugar. Low energy consuming reverse osmosis may be employed for concentrating sugar syrup without decomposing the molecules, resulting in high‐quality sugar with low cost. In this study different commercial reverse osmosis membranes (DS, DSII, PVD, FT30, BW30) and one nanofiltration membrane (NF45) were used for sugar syrup concentration. The results show that nanofiltration NF45 membrane has no effect on sugar syrup concentration. The rejections of sugar using DSII and PVD reverse osmosis membranes vary between 23 % and 33 % for different operating conditions. DS membrane rejected around 10 % of the sugar molecules in best conditions. FT30 membrane initially showed better performance (55 %). However, the rejection was decreased during time (minimum 7 %). For BW30 membrane, the rejection of sugar was better (60 %) compared to the other membranes used in this work. For two‐stage processes (i.e. the permeate of the first stage used as a feed for the second stage) the highest rejection (88 %) was obtained.     

A mechanism of respiration-dependent water uptake enhanced by auxin

Summary There are many contradictory observations on the mechanohydraulic relation of growing higher plant cells and tissues. Graphical analysis of the simultaneous equations which govern irreversible wall yielding and water absorption has made more comprehensive the understanding of this relation when relative growth rate is plotted against turgor pressure. It suggests that some respiration-dependent and auxin sensitive process might regulate the difference of osmotic potential between cells and water source. Based on anatomical and electrophysiological knowledge of the pea stem xylem, we propose the wall canal system as the mechanism of respiration-dependent water uptake which is sensitive to auxin. This system consists of the xylem apoplastic walls, the xylem proton pumps, active solute uptake system and cell membranes. In the simplest case, third-order simultaneous differential equations are involved. Numerical analysis showed that net uptake of solutes enables water to be taken up against an opposing gradient of water potential. The behaviour of this wall canal system describes well the mechano-hydraulic relation of enlarging plant cells and tissues. Recent typical, but incompatible, interpretations of this relation are critically discussed based on our model.Abbreviations V the volume of enlarging symplast - the average extensibility of the wall - Pⁱ turgor pressure - Y the yield threshold of the wall - L the relative hydraulic conductance - the solute reflection coefficient of the plasmamembrane - Cⁱ the osmotic concentration of the symplast cells - C^x the osmotic concentration of the xylem vessels - P^x hydrostatic pressure in the xylem vessels - R the gas constant - T absolute temperature - ^o water potential of xylem fluid - ⁱ water potential of symplast cells     

Kiwifruit extracts inhibit cytokine production by lipopolysaccharide-activated macrophages, and intestinal epithelial cells isolated from IL10 gene deficient mice

Inflammatory bowel disease (IBD) is a chronic, inflammatory disorder of the gastrointestinal tract involving an inappropriate immune response to commensal microorganisms in a genetically susceptible host. This study examined the effects of aqueous and ethyl acetate extracts of gold kiwifruit (Actinidia chinensis) or green kiwifruit (Actinidia deliciosa) using in vitro models of IBD. These models comprised primary macrophages and intestinal epithelial cells isolated from C57BL/5J and interleukin-10 gene deficient (Il10^−/−) mice and RAW 264.7, a murine macrophage-like cell line. All four kiwifruit extracts reduced the activation of these models after lipopolysaccharide stimulation, decreasing nitric oxide and cytokine secretion by both Il10^−/− and wild-type cells. The ethyl acetate extracts exhibited the highest anti-inflammatory activity, with almost complete suppression of lipopolysaccharide-stimulated macrophage activation. These results suggest that kiwifruit extracts have significant anti-inflammatory activity relevant to IBD. We suggest that the Il10^−/− mouse is a suitable model for further study of these compounds.     

Removal of inorganic anions from drinking water supplies by membrane bio/processes

This paper is designed to provide an overview of the main membrane-assisted processes that can be used for the removal of toxic inorganic anions from drinking water supplies. The emphasis has been placed on integrated process solutions, including the emerging issue of membrane bioreactors. An attempt is made to compare critically recently reported results, reveal the best existing membrane technologies and identify the most promising integrated membrane bio/processes currently being under investigation. Selected examples are discussed in each case with respect to their advantages and limitations compared to conventional methods for removal of anionic pollutants. The use of membranes is particularly attractive for separating ions between two liquid phases (purified and concentrated water streams) because many of the difficulties associated with precipitation, coagulation or adsorption and phase separation can be avoided. Therefore, membrane technologies are already successfully used on large-scale for removal of inorganic anions such as nitrate, fluoride, arsenic species, etc. The concentrated brine discharge and/or treatment, however, can be problematic in many cases. Membrane bioreactors allow for complete depollution but water quality, insufficiently stable process operation, and economical reasons still limit their wider application in drinking water treatment. The development of more efficient membranes, the design of cost-effective operating conditions, especially long-term operations without or with minimal membrane inorganic and/or biological fouling, and reduction of the specific energy consumption requirements are the major challenges.     

Prostaglandin E2 enhances the sodium conductance of exocrine glands in isolated frog skin (Rana esculenta)

Summary Prostaglandins are known to stimulate the active transepithelial Na⁺ uptake and the active secretion of Cl^– from the glands of isolated frog skin. In the present work the effect of prostaglandin E₂ (PGE₂) on the glandular Na⁺ conductance was examined. In order to avoid interference from the Na⁺ uptake and the glandular Cl^– secretion the experiments were carried out on skins where the Cl^– secretion was inhibited (the skins were bathed in Cl^– Ringer's solution in the presence of furosemide, or in NO ₃ ^– Ringer's solution), and the active Na⁺ uptake was blocked by the addition of amiloride. Transepithelial current, water flow and ion fluxes were measured. A negative current was passed across the skins (the skins were clamped at –100 mV, basolateral solution was taken as reference). When PGE₂, was added to the skins under these experimental conditions, the current became more negative; this was mainly due to an increase in the Na⁺ efflux. Together with the increase in Na⁺ efflux a significant increase of the water secretion was observed. The water secretion was coupled to the efflux of Na⁺, and when one Na⁺ was pulled from the basolateral to the apical solution via this pathway 230 molecules of water follwed. From the data presented it is suggested that this pathway for Na⁺ is confined to the exocrine glands.     

An artificial osmotic cell: a model system for simulating osmotic processes and for studying phenomena of negative pressure in plants

Abstract An artificial osmotic cell has been constructed using reverse osmosis membranes. The cell consisted of a thin film of an osmotic solution (thickness: 100 to 200 μm) containing a non-permeating solute and was bounded between the membrane and the front plate of a pressure transducer which continuously recorded cell turgor. The membrane was supported by metal grids to withstand positive and negative pressures (P). At maximum, negative pressures of up to –0.7 MPa (absolute) could be created within the film on short-term and pressures of up to –0.3 MPa could be maintained without cavitation for several hours. As with living plant cells, the application of osmotic solutions of a non-permeating solute resulted in monophasic relaxations of turgor pressure from which the hydraulic conductivity of the membrane (Lp) and the elastic modulus of the cell (?) could be estimated. The application of solutions with permeating solutes resulted in biphasic pressure relaxation curves (as for living cells) from which the permeability (P_s) and reflection (σ_s) coefficients could be evaluated for the given membrane. Lp, P_s, and σ_s were independent of P and did not change upon transition from the positive to the negative range of pressure. It is concluded that the artificial cell could be used to simulate certain transport properties of living cells and to study phenomena of negative pressure as they occur in the xylem and, perhaps, also in living cells of higher plants.     

Enzymatic cleaning of biofouled thin-film composite reverse osmosis (RO) membrane operated in a biofilm membrane reactor

Application of environmentally friendly enzymes to remove thin-film composite (TFC) reverse osmosis (RO) membrane biofoulants without changing the physico-chemical properties of the RO surface is a challenging and new concept. Eight enzymes from Novozyme A/S were tested using a commercially available biofouling-resistant TFC polyamide RO membrane (BW30, FilmTech Corporation, Dow Chemical Co.) without filtration in a rotating disk reactor system operated for 58 days. At the end of the operation, the accumulated biofoulants on the TFC RO surfaces were treated with the three best enzymes, Subtilisin protease and lipase; dextranase; and polygalacturonase (PG) based enzymes, at neutral pH (~7) and doses of 50, 100, and 150 ppm. Contact times were 18 and 36 h. Live/dead staining, epifluorescence microscopy measurements, and 5 μm thick cryo-sections of enzyme and physically treated biofouled membranes revealed that Subtilisin protease- and lipase-based enzymes at 100 ppm and 18 h contact time were optimal for removing most of the cells and proteins from the RO surface. Culturable cells inside the biofilm declined by more than five logs even at the lower dose (50 ppm) and shorter incubation period (18 h). Subtilisin protease- and lipase-based enzyme cleaning at 100 ppm and for 18 h contact time restored the hydrophobicity of the TFC RO surface to its virgin condition while physical cleaning alone resulted in a 50° increase in hydrophobicity. Moreover, at this optimum working condition, the Subtilisin protease- and lipase-based enzyme treatment of biofouled RO surface also restored the surface roughness measured with atomic force microscopy and the mass percentage of the chemical compositions on the TFC surface estimated with X-ray photoelectron spectroscopy to its virgin condition. This novel study will encourage the further development and application of enzymes to remove biofoulants on the RO surface without changing its surface properties.     

HIGH AND LOW DENSITY WATER AND RESTING,ACTIVE AND TRANSFORMED CELLS

Resting and active states of cells are described in terms of the expectation, derived from experiments with aqueous polymers, that they contain two modified forms of water: high density, reactive, fluid water and low density, inert, viscous water. Low density water predominates in a resting cell and is converted to high density water in an active cell. It is proposed that switching from one state to another is an integral part of cellular function. When this ability is lost cells are transformed either to a state of rigor or to a hyperactive state in which they no longer depend upon external signals.     

Membrane Processing of Fruit Juices and Beverages: A Review

ABSTRACT:?

Membrane technology for the processing of fruit juices and beverages has been applied mainly for clarification using ultrafiltration and microfiltration, and for concentration using reverse osmosis. The effects of product preparation, membrane selection, and operating parameters are important factors influencing filtration rate and product quality. Technological advances related to the development of new membranes, improvement in process engineering, and better understanding of fruit beverage constituents have expanded the range of membrane separation processes. Developments in novel membrane processes, including electrodialysis and pervaporation, increased the array of applications in combination with other technologies for alternate uses in fruit juices and beverages.