Reverse Osmosis Concentration Research Articles

Technique of Instantaneous Ultrasonic Extraction and Reverse Osmosis Concentration on Polyphenols of Chinese Herbs

Polyphenol is a kind of active compound widely existed in many Chinese herbs, easily destroyed by oxygen and heat. Extraction and concentration are key steps to protect it from destruction, and the costly energy consumption steps in the process of herbs. In order to save energy and improve polyphenol quality, instantaneous ultrasonic extraction (IUE) and reverse osmosis (RO) concentration are evaluated in this paper. IUE and RO were used to extract polyphenol separately from herbs of Phyllantuus urinaria L, leaves of Camellia sinensis L and root of Salvia miltiorrhiza Bunge. Gallic acid, EGCG and Tanshinol, the main components of polyphenols, were determined by HPLC. Their content and energy consumption were compared to that by same time water boiling (10min) or 60min ultrasonic extraction and vacuum concentration. IUE increased 1-3 times or 1-5 times polyphenol content and saved 1 or 6 times energy consumption more than the same time water boiling or 60min ultrasonic extraction. Compared with vacuum vaporization to the same solid matter content (15%), RO increased 2 times polyphennol content and consumed 1/10 times energy and 1/5 times time. Combination of IUE and RO shortens process time, significantly improves polyphenol quality and saves energy. It will be the beneficial method for polyphenol extraction and concentration of Chinese herbs.

Disinfection byproduct formation in reverse-osmosis concentrated and lyophilized natural organic matter from a drinking water source

Drinking water treatment and disinfection byproduct (DBP) research can be complicated by natural organic matter (NOM) temporal variability. NOM preservation by lyophilization (freeze-drying) has been long practiced to address this issue; however, its applicability for drinking water research has been limited because the selected NOM sources are atypical of most drinking water sources. The purpose of this research was to demonstrate that reconstituted NOM from a lyophilized reverse-osmosis (RO) concentrate of a typical drinking water source closely represents DBP formation in the original NOM. A preliminary experiment assessed DBP formation kinetics and yields in concentrated NOM, which demonstrated that chlorine decays faster in concentrate, in some cases leading to altered DBP speciation. Potential changes in NOM reactivity caused by lyophilization were evaluated by chlorination of lyophilized and reconstituted NOM, its parent RO concentrate, and the source water. Bromide lost during RO concentration was replaced by adding potassium bromide prior to chlorination. Although total measured DBP formation tended to decrease slightly and unidentified halogenated organic formation tended to increase slightly as a result of RO concentration, the changes associated with lyophilization were minor. In lyophilized NOM reconstituted back to source water TOC levels and then chlorinated, the concentrations of 19 of 21 measured DBPs, constituting 96% of the total identified DBP mass, were statistically indistinguishable from those in the chlorinated source water. Furthermore, the concentrations of 16 of 21 DBPs in lyophilized NOM reconstituted back to the RO concentrate TOC levels, constituting 86% DBP mass, were statistically indistinguishable from those in the RO concentrate. This study suggests that lyophilization can be used to preserve concentrated NOM without substantially altering the precursors to DBP formation.

Evaluating RO performance with biological pretreatment of graywater

Reverse osmosis (RO) is a treatment technology that may be used for the recovery of graywater terrestrially as well as the recovery of wastewater on board long duration, manned space flights. As with terrestrial RO applications, concentration polarization and membrane fouling lead to decreased productivity and increased energy demands with time. Physiochemical and biological pretreatment options can enhance the performance of the RO system; also, biological pretreatment has the advantages of low energy and consumable requirements as compared to other physiochemical pretreatment options. To determine the degree to which the incorporation of biological treatment enhances RO performance, a series of bench-scale experiments were performed. Observed resistances indicate that biological pretreatment alleviated the degree of non-reversible fouling while also improving the rate of permeate flux in a downstream RO process to further treat water. Results also indicated that enhanced urea hydrolysis, pH reduction, and carbon oxidation serve as the primary benefits of biological pretreatment of space-based graywater. The observations of this study may also benefit engineers considering the treatment of graywaters for terrestrial water-reuse applications.

Reverse osmosis concentration of press liquid from orange juice solid wastes: Flux decline mechanisms

Orange juice production produces high amount of solid waste. An alternative for these wastes is their pressing with lime to obtain a press liquor stream and a dried solid for cattle feeding. The press liquor (around 10 °Brix) is traditionally concentrated up to 70 °Brix (citrus molasses) by multiple effect evaporation. In this investigation, reverse osmosis is evaluated as an alternative for press liquor preconcentration. Two synthetic feed solutions were studied, one included pectin in its composition (WP) and the other lacked pectin (WOP) to simulate a previous depectinization of WP. The concentration process was evaluated in terms of some selected parameters (chemical oxygen demand, total soluble solids, total dissolved solids and osmotic pressure). The fouling mechanism as well as the membrane resistance to the permeate pass were assessed. It was found that for later stages of concentration cake filtration was the dominant fouling mechanism while for earlier stages, the mechanism found was the complete pore blocking. The presence of pectin not only maximized the membrane fouling but also led to worse permeate quality.

Process optimisation of the bitter gourd (Momordica charantia) concentrated juice preparation for a freeze‐dried powder

SummaryBitter gourd (Momordica charantia), a commonly consumed vegetable in South Asia, eastern‐South Asia, China, Japan, Korea peninsula, Caribbean Sea isles etc., is used as an adjunct in the management of diabetes mellitus. In this study, in order to find the effective ways of producing bitter gourd freeze‐dried powder, the concentrated juice of bitter gourd was produced through enzymatic process (EP), ultra filtration (UF), reverse osmosis and vacuum concentration technology. Results indicated that total saponins, total sugar and pH value in bitter gourd juice were almost unchanged after EP and after UF (P ≥ 0.05). However, UF decreased the turbidity and improved transmittance of juice (P < 0.05). When compared with the vacuum concentration alone, the combined process of reverse osmosis followed by vacuum concentration had 3.33 folds of production efficiency and 1.725 times of vitamin C content in concentrated juice. With freeze‐drying microscope system, the eutectic point of the freeze‐dried product of bitter gourd juice was detected to be −37.5 °C, which was important to optimise lyophilisation parameters. The freeze‐drying microscope system was more accurate than the conventional electric resistance method in detecting the eutectic point of freeze‐dried product.

Recovery of l-tryptophan from crystallization wastewater by combined membrane process

The combined membrane process of electrodialysis (ED) and reverse osmosis (RO) was carried out to recover the l-tryptophan from its crystallization wastewater which had 0.5–1.5% residual l-tryptophan and around 15% impurity of NaCl salt. In the process of ED desalination, the operating current should be controlled below the limiting current density to avoid the polarization phenomenon. The pH of dilute solution significantly affected the recovery ratio of l-tryptophan, and the salt removal ratio varied with current density and voltage. The operating current density also had a great impact on the performance of the electrodialytic desalination process. After ED desalination, two methods including raising the temperature and adjusting the pH of the dilute solution coming from ED process were used to increase the solubility of l-tryptophan in aqueous solution during the RO concentration process. It was observed that the recovery ratio of l-tryptophan was closely correlated with not only the pH of RO feed but also the salt removal degree of ED process. After the treatment of the combined ED and RO process, 60.4% of the optimal recovery ratio of l-tryptophan was achieved, and the purity of final product of l-tryptophan reached 98%.

Scale formation in reverse osmosis desalination: model development

Scale formation of soluble salts is one of the major factors limiting the performance of reverse osmosis (RO) membranes for desalination. In this study, a dynamic model based on the crystallization theory was developed to analyze the effect of CaSO 4 scale formation on RO desalination process. Taking into consideration two mechanisms in scale formation including surface and bulk crystallization, the performance of RO filtration was predicted as a function of crossflow velocity, transmembrane pressure, permeate recovery, and operation mode. The model results indicated that RO fouling due to surface crystallization is important in batch filtration whereas both surface and bulk crystallization is important in crossflow filtration. This is because concentration polarization is directly related to surface crystallization. RO fouling due to bulk crystallization appeared to increase with increasing crossflow velocity and permeate recovery. The effects of background organic matters and antiscalant on scale formation were quantified using the model. The effect of operating parameters on RO fouling and concentration polarization was explored based on the model analysis.

Dissolved organic matter from treated effluent of a major wastewater treatment plant: Characterization and influence on copper toxicity

A combination of reverse osmosis (RO) concentration and DAX-8/XAD-4 resin adsorption techniques is used to isolate the various constituents of urban dissolved organic matter (DOM) from inorganic salts. Three fractions: hydrophobic (HPO), transphilic (TPI) and hydrophilic (HPI) accounting respectively for 35%, 20% and 45% of extracted carbon, are isolated from effluents of a major French wastewater treatment plant. This atypical DOC distribution, in comparison with natural water where the HPO fraction dominates, shows the significance of HPI fraction which often gets neglected because of extraction difficulties. A number of analytical techniques (elemental, spectroscopic: UV, FTIR) allow highlighting the weak aromaticity of wastewater effluent DOM (EfOM) due to fewer degradation and condensation processes and the strong presence of proteinaceous structures indicative of intense microbial activity. Copper toxicity in the presence of DOM is estimated using an acute toxicity test on Daphnia Magna (Strauss). Results reveal the similar protective role of each EfOM fraction compared to reference Suwannee river fulvic acid despite lower EfOM aromaticity (i.e. specific UV absorbance). The environmental implications of these results are discussed with respect to the development of site-specific water quality criteria.

Separation of nutrients from mine water by reverse osmosis for subsequent biological treatment

Nutrients such as ammonium and nitrate from different sources in mining and mineral processing are often discharged during mining operation to surrounding aquatic environment. The aim of this study was to evaluate the applicability of reverse osmosis (RO) to concentrate ammonium and nitrate from three different mine waters for subsequent removal of nutrients from the concentrate in bioreactors. In initial membrane selection tests, reverse osmosis retained the nutrients and the most suitable membrane was studied for subsequent concentrating tests. The volume reduction factor was up to 20. Ammonium and nitrate were enriched by reverse osmosis 3.6 and 5.7 times, respectively. Total salinity increased about 1.5 times in the RO-concentrate. Iron, copper, zinc, lead and cadmium, potential inhibitors of bacteria, were enriched to the brine of mine water 2. In general, the permeate pH decreased slightly during the reverse osmosis concentration. The produced RO-concentrate was suitable for biological removal of total nitrogen. Prevention of membrane fouling due to suspended solids requires prefiltration of feed prior to reverse osmosis. It was estimated that the total costs for reverse osmosis with prefiltration of feed is about 0.34 €/m 3.

Separation of phenols and furfural by pervaporation and reverse osmosis membranes from biomass – superheated steam pyrolysis-derived aqueous solution

The separation of valuable chemicals from raw products, where a great number of chemicals coexist, is the key technology in biomass refinery. In this study, the applicability of membrane separation of valuable chemicals from our currently developed portable superheated steam (SHS) biomass pyrolysis process was demonstrated. Phenols (phenol, p-cresol, guaiacol, methyl guaiacol, and ethyl guaiacol), furfural, and acetone were successfully separated by pervaporation using the silicone rubber membrane from model solutions and an actual SHS derived aqueous solution. The solution was also concentrated effectively by reverse osmosis separation using a polyamide membrane. When a high concentration of SHS solution was fed to the pervaporation process, a phase-separated permeate was obtained, which indicated that the reverse osmosis concentration combined with pervaporation separation is useful for the superheated steam process.

Economic evaluation of an integrated process for lactic acid production from ultrafiltered whey

Lactic acid can be manufactured either by chemical synthesis or by fermentative processes. In recent years, the amount of lactic acid obtained by biotechnological methods has increased. The highest cost in the traditional process of lactic acid production by carbohydrate fermentation lies in the separation steps that are needed to recover and purify the product from the fermentation broth. An integrated process for food grade lactic acid production from whey ultrafiltrate is evaluated in this work. This process consists in the following steps: fermentation, ultrafiltration, ion exchange, reverse osmosis and final concentration by vacuum evaporation. The proposed process was demonstrated to be economically viable. The annual cost resulted to be 1.25 US$/kg for 50% (w/w) lactic acid. The highest contribution to the total investment cost corresponds to the concentration step, representing 40% of the total cost, whereas the fermentation step requires the highest operating cost (47% of the total operating cost).

Multi-step membrane processes for the concentration of grape juice

Grape production and viticulture have great traditions in Hungary. Nowadays wine-making is only profitable if the end-product is quality wine. Good-quality wine can be produced from must which has the proper high sugar content. If there is an unfavorable vintage, it is necessary to enrich the must, to increase its sugar content and to eliminate its other defects. Grape juice is not only a sweetener; it can be used for other purposes too because the juice of the grape is a pleasant, fashionable soft drink as well. However, the must storage can cause some difficulties, as fermentation starts easily. The aim of the investigations was to use osmotic distillation and membrane distillation after the microfiltration and reverse osmosis concentration [1] for water removal from grape juice in order to reach a high sugar content, to the extent that makes it possible to preserve the grape juice without cooling.

Concentration of aqua solutions of organic components by reverse osmosis. I: Influence of trans-membrane pressure and membrane type on concentration of different ester and aldehyde solutions by reverse osmosis

Volatile aroma components of fruit juices are lost with vapour during concentration by evaporation. However, these components are mostly retained in fruit juice by membrane processes concentration. Application of reverse osmosis for concentration of ester and aldehyde solutions, being components of apple juice aroma, was investigated. Influence of process pressure, percentages of different esters and aldehydes (0.01% v/v, 0.05% v/v and 0.1% v/v), influence of molecule structure, molecular mass and membrane type on concentration of model solutions of esters and aldehydes by reverse osmosis were studied. Effects of activity and activity coefficient of esters and aldehydes on concentration were investigated too. Research was carried out with model solutions of esters (ethyl acetate, butyl acetate, hexyl acetate, amyl acetate, iso-amyl acetate, iso-amyl propionate, ethyl butyrate, ethyl 2-methyl butyrate) and aldehydes (hexanal, trans-2-hexenal). Reverse osmosis concentration was carried out on laboratory equipment with plates and frames using two types of composite membranes (aromatic polyamide membrane HR 95 PP of 95% NaCl rejection and HR 98 PP of 97.5% NaCl rejection). Aroma components (esters and aldehydes) of the retentate and permeate were determined by gas chromatography with a mass detector (GC/MS) and a “head space” technique. Results of this research showed that ester and aldehyde water solutions of different molecular mass and structure could be concentrated successfully by reverse osmosis. These results also give a better insight into mechanisms of aroma compounds retention (esters, aldehydes) in the retentate, during concentration of water solutions by reverse osmosis. On the membrane HR 98 PP was greater retention of esters: ethyl acetate, butyl acetate, ethyl butyrate and ethyl 2-methyl butyrate than the membrane HR 95 PP. On the membrane HR 95 PP was greater retention of esters: hexyl acetate, amyl acetate, iso-amyl acetate, iso-amyl propionate and aldehydes: hexanal and trans-2-hexenal than the membrane HR 98 PP. Concentration factor was higher in the retentate and OCP (organic components passage) was lower in the permeate when ester and aldehyde portions in the feed solution and molecular mass were greater. Ester concentration of n-structural form showed a greater concentration factor in the retentate and lower OCP (organic components passage) in the permeate. The greater retention in the retentates was realised by aldehyde concentration with a double bond in the molecule. Membrane selectivity and retention of esters and aldehydes was greater in the retentate than in the permeate with application of higher process pressure.

Electrodialysis Desalination and Reverse Osmosis Concentration of an Industrial Mussel Cooking Juice: Process Impact on Pollution Reduction and on Aroma Quality

ABSTRACT: An industrial mussel cooking juice was treated by a 3‐step process to produce a natural aroma concentrate and a cleaned water stream. The juice was centrifuged before being desalinated by electrodialysis and then concentrated by reverse osmosis. As a result of this combined process, most of the physicochemical properties of the reverse osmosis permeate were reduced below the discharge standards. The concentrate was examined by a trained sensory panel (triangular tests, sensory profiles) and by gas chromatography/mass spectrometry. The sensory profile of the concentrate was shown as slightly different from the unprocessed mussel cooking juice one. Nevertheless, the concentration process preserved the native characteristic aroma of the cooked mussel, of interest to human or pet food industries.

Concentration of Apple Juice by Reverse Osmosis at Laboratory and Pilot-Plant Scales

The aim of this work was to predict the rejection of aroma compounds and permeate flux during the reverse osmosis concentration of apple juice at laboratory and pilot-plant scales. For the concentration, the MSCB2521 R99 and MSCE 4040 R99 spiral wound membranes (Separem, SpA, Biella, Italy) were used at laboratory and pilot-plant scales, respectively. The preferential sorption-capillary flow model was considered for the calculations. Experiments were performed at different transmembrane pressures (1.5−7.0 MPa), feed flows (200−600 L/h at laboratory scale and 4200 L/h at pilot-plant scale), temperatures (20−30 °C), and concentrations (10.0−22.7 °Brix). Good agreement between experimental and estimated data was observed for most of the aroma compounds and operating conditions used. When working at 7.0 MPa transmembrane pressure, 4200 L/h feed flow, and 25 °C temperature, concentrations higher than 22 °Brix can be reached with high permeate fluxes (higher than 25 L/h·m2) and high aroma retention (higher than...

Prediction of Flux and Aroma Compounds Rejection in a Reverse Osmosis Concentration of Apple Juice Model Solutions

The aim of this work was to predict the rejection of aroma compounds and permeate flux during the reverse osmosis concentration of model solutions simulating apple juice. For the concentration, the MSCB2521 R99 spiral-wound membrane (Separem SpA, Biella, Italy) was used. The preferential sorption−capillary flow model was employed for this purpose. Water and aqueous solutions of apple juice aroma were used to determine the parameters included in the model. Then, the model was tested with aqueous solutions of glucose and aroma compounds. Experiments were performed at different transmembrane pressures (1.5−3.5 MPa), feed flow rates (200−600 L/h; Reynolds numbers = 51−190), temperatures (15−30 °C), and glucose concentrations (9.1−17.0 °Brix). Good agreement between experimental and estimated data was observed for most of the aroma compounds and operating conditions used.

A comparative study of reverse osmosis and freeze concentration for the removal of valeric acid from wastewaters

The recovery of valeric (n-pentanoic) acid from a synthetic aqueous solution simulating a wastewater stream in nylon manufacturing has been carried out using freeze concentration and reverse osmosis as separation processes. The concentration of valeric acid in aqueous solutions was in the range of 0.5–25 g/L. Reverse osmosis was carried out at 20 and 40°C and at a transmembrane pressure in the range of 1.3 to 6.0 MPa. The feed flow rate was 2 m/s in all the experiments. Although no membrane fouling was observed under the experimental conditions tested, a strong interaction of the acid with the membrane was noticeable. Rejections of the order of 90% were observed at 20°C, while values below even 50% were found at 40°C. The optimum performance for freeze concentration was determined, the best conditions being −10°C of subcooling temperature and 1012 kg/hm of feed flow. A model based on the heat transfer balance allows to predict the rate of ice crystallization. An economic analysis reveals that although freeze concentration consumes as much as five times the energy of reverse osmosis, which is compensated by the high costs of membrane replacement in reverse osmosis.

Osmotic dehydration coupled reverse osmosis concentration: steady-state model and assessment

A steady-state analysis was made for evaluating the RO concentration of sugar solutions assisted by flowing a brine solution in counter-current mode through the permeate side. Calculations show that membrane area requirements for high solute concentrations could be reduced by combining RO with osmotic dehydration. The area requirements are sensitive to salt concentration polarization on the permeate side, particularly when low feed pressures are used. It appears feasible to design membranes/modules with low enough values of permeate side concentration polarization to enable effective feed solution concentration

Simmondsin concentrate from defatted jojoba meal

A water-extract of defatted jojoba meal was filtered and concentrated from 2.6 to 23% solids on a pilot scale in a reverse osmosis concentration apparatus and then freeze-dried. The characteristics of the membrane and new concentrator were determined with both glucose and the water-extract from jojoba meal. Permeate flux was not significantly affected by the change in total flow within the controllable limits at 1, 2, 10, or 20% glucose concentration. With the total flow past the membrane maintained at 57 1/m, the permeate flux was measured at various concentrations and at different pressures across the membrane. A permeate flux rate of 2.21 × 10 −5 m/s could be maintained for glucose concentrations up to 20%. For the extract, pressure across the membrane was adjusted to maintain a permeate flux of 1.24 × 10 −5 m/s (3.8 1/min for a 5.1 m 2 surface area membrane) not exceeding the system limit of 6.9 MPa. Using this method, 193 1 of 2.6% solids jojoba extract could be concentrated to 25.3 1 of 19.7% solids in 45 min. Permeate flux decreased with time because maximum pressure could not maintain a flux rate of 1.24 × 10 −5 m/s at the higher solids concentrations. The average permeate flux over the entire experiment was 0.99 × 10 −5 m/s. Based on the pilot scale tests, 568 kg of meal were extracted and processed on industrial equipment. The process included a vacuum drum dryer coated with diatomaceous earth with spray-drying of the concentrate. A powdery solid containing 42% simmondsin and related analogues was obtained. The results of the industrial trials and recommendations for process improvements are discussed.

Economic comparison of transverse and longitudinal flow hollow fiber membrane modules for reverse osmosis and ultrafiltration

The presently used hollow fiber membrane modules consist of a bundle of fibers in a cylindrical polymer or metal shell parallel to the shell axis. The feed solution flows either through the lumen or at the outside parallel to the fibers. This paper compares the performance of these modules with a new transverse flow module where the hollow fibers are positioned perpendicularly to the flow direction. For both types of modules the product costs are calculated for desalination by reverse osmosis and Dextran concentration by ultrafiltration. These calculations are based on literature data. The main conclusion is that the application of the tr`ansverse flow module is only attractive if the permeation resistance is mainly determined by the hydrodynamics (ultrafiltration) and not attractive if the membrane permeability is the main resistance (reverse osmosis).