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The development of cleaning strategies for RO membranes processing highly charged wastewaters requires knowledge about foulant composition. The objective of this study was to characterize the fouling layer that formed on RO membranes processing swine wastewater pretreated by a mechanical solid-liquid separator (LF) and aerobic biofiltration (AE). The two LF effluents represented swine wastewater concentrated three (LF1) and four (LF2) times with BW30 (36 bar) and SW30 (60 bar) membranes, respectively. Flux decline was slightly higher with LF2-SW30 (37.1%) than LF1-BW30 (31.8%) after 20 h of filtration. The fouling layer had significantly higher protein concentration on LF2-SW30 than on LF1-BW30, but both had similar microbial content and inorganic composition. The AE effluents were concentrated by a factor of 7 and processed at pH 5.75 (AE1) and 8.07 (AE2) with BW30 membranes. Both AE effluents had higher calcium but lower suspended solids and organics than the LF effluents. They generated significantly higher flux decline and biofouling than LF1. High flux decline was also associated with increased protein attachment for AE1 and inorganic fouling for AE2. A mechanical separator may be adequate to prepare swine wastewater for RO filtration but the aerobic pretreatment would allow for a higher volumetric concentration of the effluent. [ABSTRACT FROM PUBLISHER]

There & an increased interest in the application of reverse osmos& (RO) technology to treat agricultural wastewaters because RO membranes can produce reusable water and recover valuable nutrients. With highly charged wastewater, however, membrane replacement could represent an important fraction of the operating costs. The objective of this project was to study the aging process of spiral-wound RO elements (BW30 and SW30) processing swine wastewater. The membrane elements were subjected to 21 h concentration-filtration (CF) cycles followed by a 1 h chemical cleaning and a weekly 3 d soaking period. The BW30 element experienced a 22% increase in intrinsic membrane resistance (Rm), defined as resistance to water flux through the membrane, after the first four CF cycles with swine wastewater. This rapid increase was mainly caused by irreversible compaction of the membrane under high pressures. The SW30 membrane had a lower compressibility, and Rm only increased by 7% in the first four cycles. After this initialperiod, small but steady increases in Rr, were mainly attributed to the accumulation of foulants on or within the membranes. However, a 40% increase in Rm after 42 CF cycles with the BW30 membrane had little impact on permeate flux during swine wastewater filtration because permeate flux was mainly controlled by fouling and substrate-related resistances. All membrane elements maintained their ionic retention efficiency throughout the experiment, indicating no damage to the integrity of the membrane during the CF and cleaning cycles. Projection based on a total of 42 and 20 CF cycles for the B W30 and SW30 membranes, respectively, suggested that Rm would rapidly increase in the initial 12 CF cycles of swine wastewater filtration, by 29% and 11%for the BW30 and SW30 membranes, respectively, mainly due to compaction. Between cycles 12 and 624, Rm would further increase by 32% and 16%for the BW30 and SW30 membranes, respectively. This number of cycles corresponds to three years of operation using the same operational procedures as those described in this study. With proper care, the membrane elements may not need to be replaced for at least three years. However, these predictions remain to be verified in a commercial setting. [ABSTRACT FROM AUTHOR]

Abstract: The aim of the present study was to: (1) identify the nature of fouling for ED membranes (AMX and CMB, from Tokuyama Soda, Japan) used for the isolation and concentration of total NH3–N from swine manure, (2) determine the effect of fouling on membrane integrity, (3) establish the relation between fouling type and manure composition, and (4) estimate the efficiency of a two-step cleaning procedure to restore membranes properties. After processing 10 batches of swine manure (or 240L/m2), the average current density as well as the membranes electrical conductivity and ion-exchange capacity decreased. The decline in process performance was associated with membrane fouling, since a significant deposit, possibly calcium carbonate and silica colloidal particles, was observed on the fouled AMX membranes. The electrical conductivity and ion-exchange capacity of the CMB membrane was completely restored by a two-step cleaning procedure using 0.5% NaOH and 1% HCl. However, for the electrical conductivity of the AMX membranes it was only partially recovered. The on-line cleaning procedure efficiency was assessed by measuring the stack average current density and the decrease of manure conductivity during 1h tests. Values for the cleaned membranes were, respectively, 95% and 91% the ones measured with the new membranes, and were significantly higher than for the fouled membranes. [Copyright &y& Elsevier]

This project aimed at producing a concentrated nitrogen fertilizer from liquid swine manure using electrodialysis (ED) and reverse osmosis (RO), as a mean to help resolve the excess nutrient problem faced by many swine producers, and offer an alternative to chemical nitrogen fertilizer production. Different types of ED membranes were evaluated based on the transfer rate, current efficiency and membrane stability. A combination of CMB/AMX membranes was retained due to its high transfer rate and chemical stability. The maximum total ammonia concentration (NH3–N) achievable by ED was limited by water transport from the manure to the concentrate compartment, and ammonia volatilization (17%) from the open concentrate compartment. Results suggested that, under the conditions of this experiment, a maximum total NH3–N concentration of about 16g/L could be reached with the ED system. An ED concentrate (8.7g/L of total NH3–N) was also fed to TFC-HF reverse osmosis membranes. A mass balance analysis revealed that the RO permeate, which represented 49.6% of the initial volume, contained 8.6% of the ammonia. However, the RO concentrate contained only 66.6% of the initial total NH3–N, suggesting that 21.2% of the ammonia was volatilized during the concentration test with RO membranes. Ammonia concentration in the RO concentrate reached approximately 13g/L, which is similar to the maximum concentration that could be achieved by ED. These results suggest that the use of ED and RO membranes to recover and concentrate ammonia is potentially interesting but the process must include an approach to minimize ammonia volatilization or trap volatilized ammonia. [Copyright &y& Elsevier]

Abstract: Apple Juice industry is in search of a simplified technology which enables a quick clarification and stabilisation of apple juice. This study aimed to evaluate the potential of electroflotation as an alternative for the clarification of apple juice. Clarification of apple juice by electroflotation was first done at various current densities (10, 20 and 40 mA/cm2) with and without addition of gelatin (200 mg/l). Afterwards, the electroflotation treatments were done at a current density of 20 mA/cm2 with various concentrations of added gelatin (0, 50, 100 and 200 mg/l). It was shown that electroflotation treatments alone was efficient to reduce the tannin and protein contents of apple juice. However, the decrease in the protein content was in large part due to the use of pectinases prior to the electroflotation treatments. The use of gelatin in combination with the electroflotation aided in the clarification process. The highest gelatin concentration used in this study (200 mg/l) resulted in a better reduction of tannin and protein levels, while a current density of 20 mA/cm2 was found to be optimal. Turbidity observed in the juices clarified with electroflotation treatments was in average lower than 10 NTU but higher than 2 NTU which is generally required to produce a stable clarified juice. Brix degree and pH of the apple juice was not affected by the electroflotation treatments while the color was improved. Industrial relevance: The production of clarified and stable apple juice is a subject of interest for the beverages industries. The clarification step which remained long and discontinuous implied the addition of a large quantity of pectolytic enzyme and of clarifying agents (such as gelatin) to the freshly pressed juice to induce the precipitation of proteins and other suspended matter in 15–20 h. Fining treatments were followed by a separation step usually consisting of decantation and classical filtration on filter-press, or flotation by dispersed gas. The development of membrane separation processes to replace the traditional approach has enabled the automation of the whole production resulting in lower labor requirement and a considerably shorter process time than the traditional process. However, the performance of membrane separation processes is influenced by the declining permeate flux with time, which is due to membrane fouling. In some instances, permeate flux decline makes membrane separation processes unattractive for the clarification of apple juice. To our knowledge, we are the first research group to use electroflotation (EF) for clarification of apple juice. It was shown that EF treatments alone were efficient to reduce the tannin and protein contents of apple juice. In addition, the use of gelatin in combination with the EF aided in the clarification process. Turbidity observed in the juices clarified with EF treatments for 30 min was in average lower than 10 NTU. Brix degree and pH of the apple juice were not affected by the EF treatments while the color was improved. When compared to the values reported in the literature for flotation by dispersed gas, it seems that EF shows better efficiency than flotation in decreasing the juice turbidity (99% decrease for EF as compared to 90% decrease for flotation). In addition, for experiments carried out by conventional flotation larger amount of fining agent are used (70–150 mg of gelatin/l, 400–800 mg/l of silica sol and 200–500 mg/l of bentonite). For these reasons, the new process we propose is advantageous when compared to the traditional flotation approach and it should have a measurable impact on the advancements in the production of clarified apple juice. If used as a pre-treatment to ultrafiltration clarification, it is expected that it would reduce membrane fouling resulting in higher productivity. [Copyright &y& Elsevier]

Abstract: The purpose of this work was to develop a process enabling the quick inactivation of the polyphenol oxidase and pectin methylesterase enzymes, which are present in cloudy or unclarified apple juice; These enzymes are respectively responsible for enzymatic browning and opalescence instability. In order to fulfill this objective, acidification of the apple juice to pH 2.0 was conducted by electrodialysis (bipolar–anionic membranes) followed by mild heat treatment at temperature of 40, 45 and 50°C for a duration of 0–60min. Then, juice pH was readjusted to its initial value by electrodialysis with bipolar–anionic membranes. It was shown that a mild heat treatment at 45°C for 5min performed on the acidified juice represents an appropriate condition to quickly inactivate the enzymes. Furthermore, the organoleptic properties of the juice after treatment were found to be preserved and the adjusted juice (pH readjusted to its initial value) shows a better color than an untreated apple juice. Opalescence of the adjusted juice was also more stable than for an untreated cloudy apple juice, when stored at 4°C for 3 months. [Copyright &y& Elsevier]

Abstract: The purpose of this work was to assess ionic transport, during electro-acidification of apple juice, and its influence on the acidification rate and energy usage. In order to fulfill this objective, advanced current–voltage characterization of monopolar (cationic and anionic) and bipolar membranes was carried out. Experiments were conducted using two electrodialysis configurations (bipolar-cationic membranes and bipolar-anionic membranes) with two different systems (KCl–KCl and KCl–juice). For the bipolar-anionic configuration, the system HCl–juice was also considered. The characteristic values of the transmembrane potential and of the estimated membrane resistance were correlated to the ionic transport through the membranes, and to the energy usage of the systems. Influence of the membrane boundary layers on the transmembrane potential was also investigated by working at different feed flow rates. It was shown that for the present operating conditions, the boundary layers do not affect the transmembrane potential. Furthermore, use of HCl with the bipolar-anionic configuration enables to benefit from the advantages of each configuration: a small anionic membrane resistance due to the transport of H+, as for the bipolar-cationic configuration, and a high acidification rate of the apple juice due the neutralization of OH- by HCl. It was for this system that the acidification rate was the fastest. [Copyright &y& Elsevier]

The present study emerges from the development of a process aimed at integrating electro-acidification and ultrafiltration for the production of soy protein isolate. It was observed that electro-acidification treatments, which change the pH and the salt content of the soy protein extracts, influence the permeate flux during dead-end ultrafiltration. The effects of electro-acidification treatments on the soy protein extracts were quantified through experimental measurement of particle size distribution, molecular weight profiles, protein solubility and particle volume fraction. A criterion for the particle deposition into the concentrated layer or at the membrane surface was obtained from the analysis of the net force along the direction of permeation. The particle size distribution and the criterion for the particle deposition were used to obtain information about the particle transport into the concentrated layer, as a function of the pH and salt content, and were related to the global resistance, which is mainly attributable to both concentrated layer and cake layer together. For soy protein extracts reconstituted in double distilled water or in 0.12 M KCl, it was found that particle size distribution vary with pH and salt content and this was mainly attributable to the aggregation–disaggregation behavior of the different proteins fraction. For the soy protein extracts reconstituted in double distilled water, the mean particle size, the particle transport into the concentrated layer and the global resistance were maximum at pH 7, slightly lower at pH 6 and minimum at pH 9. This resulted in minimum permeate flux at pH 7, slightly higher at pH 6 and maximum at pH 9. For the soy protein extracts reconstituted in 0.12 M KCl, all three parameters increased with a decrease of pH. This resulted in a permeate flux decrease with a decrease of pH. [Copyright &y& Elsevier]

Examines the role of cake particle solidosity in the context of the shear-induced diffusion model for membrane-dominated microfiltration. Polydisperse particle suspension; Particle adhesion; Viscosity of polarization layer.

The role of the cake particle solidosity in the context of the shear-induced diffusion model for membrane dominated microfiltration is presented. First the concept of shear-induced diffusion is reviewed to illustrate the importance of the particle solidosity in the formation of the cake. The diffusivity for concentrated suspension is subsequently presented. The estimation of the particle solidosity of the cake for monodisperse and polydisperse feed suspension is discussed. In the context of polydisperse particle suspension, an approach based on the particle adhesion concept for the estimation of the average particle radius in the various regions of the membrane filter is presented. This approach is combined with the shear-induced diffusion model for the estimation of the cake solidosity and the investigation of the viscosity and is illustrated using the experimental data of Romero and Davis for the microfiltration of large particle sizes [J. Membr. Sci., 62 (1991) 249–273]. This analysis indicates that the solidosity varies along the membrane surface with maximum predicted solidosities ranging from 0.57 to 0.66. Expressions for the viscosity of concentrated suspension are also discussed. [Copyright &y& Elsevier]

A modification of the shear induced diffusion model for membrane dominated microfiltration experiments of polydisperse suspension is presented. The particle adhesion concept provided estimation of the average particle radius in the various regions of the membrane filter. This approach enabled the estimation of the solidosity at the cake surface and the cake resistance from a knowledge of the feed particle size distribution, the cake thickness and other operating conditions using the experimental data for polydisperse suspension microfiltration of Romero and Davis (J. Membr. Sci. 62 (1991) 249) where large sizes of particles were used in a rectangular plate microfilter. This analysis showed that the solidosity varies along the membrane surface with maximum predicted solidosities ranging from 0.57 to 0.66. Estimated cake resistance, 2.84×108–4.95×109 m−1, confirms the hypothesis of negligible cake resistance as compared to typical membrane resistance, 1×1011 m−1. [Copyright &y& Elsevier]

The practice of intensive animal production in certain areas has resulted in excessive manure production for the available regional land base. Consequently, there is a need to develop treatment technologies to recover the valuable nutrients that manure contains so that the resulting product can be transported and used as fertilizer on agricultural land. The project presented here used electrodialysis in a dilution/concentration configuration to transfer the manure ammonia in the diluate solution by electromigration to an adjacent solution separated by an ion-exchange membrane under the driving force of an electrical potential. Then, air stripping from the electrodialysis-obtained concentrate solution without pH modification was used to isolate the ammonia in an acidic solution. An optimal process operating voltage of 17.5 V was first determined on the basis of current efficiency and total energy consumption. During the process, the swine manure pH varied from 8.5 to 8.2, values favourable for electromigration. Total ammonia nitrogen reached 21 352 mg/L in the concentrate solution, representing approximately seven times the concentration in the swine manure. Further increases in concentration were limited by water transfer from the diluate solution due to electroosmosis and osmosis. Applying vacuum to the concentrate reservoir was found to be more efficient than direct concentrate solution aeration for NH3 recuperation in the acid trap, given that the ammonia recuperated under vacuum represented 14.5% of the theoretical value of the NH3 present in the concentrate solution as compared to 6.2% for aeration. However, an excessively low concentrate solution pH (8.6–8.3) limited NH3volatilization toward the acid trap. These results suggest that the concentrate solution pH needs to be raised to promote the volatile NH3 form of total ammonia nitrogen. [Copyright &y& Elsevier]

The increasing use of membranes to treat a broad range of wastewaters requires the development of efficient cleaning strategies. The objective of this study was to optimize the efficiency of EDTA-SDS-NaOH solutions to recover flux and remove proteins and bacteria from RO membranes filtering swine wastewater. At 60-min cleaning time, flux recovery (FR) increased with SDS concentrations up to 18 mM, but decreased at 36 mM. Adding up to 20 mM EDTA to the SDS solutions did not improve FR. The SDS-NaOH solutions yielded higher FRs at pH 11/40°C and pH 12/33°C than pH 10/45°C, indicating that increasing pH had a greater impact on cleaning efficiency than increasing temperature. At pH 11/40°C and pH 10/45°C, increasing cleaning time from 60 to 120 min decreased FR at all SDS concentrations, probably because of surfactant adsorption on membrane surface, as opposed to inadequate foulant removal, since residual protein concentration was lower on membranes cleaned for 120 than 60 or 30 min. At pH 12/33°C, however, increasing cleaning time to 120 min improved FR at all SDS levels. The lower temperature or higher pH may have prevented surfactant attachment to the membrane. At pH 12/33°C and 120 min, a solution containing NaOH only yielded similar FRs than an 18-mM SDS solution after up to four consecutive fouling-cleaning cycles. Increasing cleaning time and pH would thus eliminate the need to add a surfactant to the cleaning solution. [ABSTRACT FROM AUTHOR]

The aim of this work was to develop a model of the water uptake by yellow peas during the steeping step of a malting process to serve for the selection of most appropriate time-temperature conditions. TAvo empirical (Peleg and lag phase equations) and three mechanistic models (Fick law analytical solution with and without consideration of the surface resistance to mass transfer and a comprehensive model coupling mass transfer and mechanical deformation) were developed. The coupled mass transfer and mechanical deformation model (RMSE = 0.025, R² =0.98), the Peleg equation (RMSE = 0.025, R2 = 0.97) and Fick law analytical solution with consideration of the surface resistance to mass transfer (RMSE = 0.026, R2 = 0.97) provided the best description of the water uptake of peas measured at five temperatures. The coupled mass transfer and mechanical deformation model provided accurate estimate of the volume of peas at saturation. A sensitivity analysis indicated that the mechanical deformation has negligible effect on the water absorption while the most important model components for appropriate estimation of the water content of peas during steeping were the rate constant for the Peleg equation and the surface mass transfer coefficient for the mechanistic models. [ABSTRACT FROM AUTHOR]

Highlights: [•] A mechanistic model considering internal water evaporation is developed. [•] The model accurately predicts internal moisture profiles at low and high temperatures. [•] Water is mostly transported in the liquid state during pasta drying. [•] Capillarity is the dominant mass transfer mechanism in pasta drying. [•] Diffusivities and mass transfer coefficients most affect pasta estimated drying time. [Copyright &y& Elsevier]

Highlights: [•] Quantification of pasta predicted required drying time uncertainty. [•] Characterization of pasta critical drying models parameters. [•] Mapping of pasta glassy, rubbery and transition state. [•] Development of a correlation linking pasta water diffusivity to processing conditions. [Copyright &y& Elsevier]

Abstract: In this study, two methods, isoelectric precipitation (IEP) and ultrafiltration (UF) were optimised for the extraction of proteins from yellow pea, desi and kabuli chickpeas, red and green lentils. For IEP, the following optimal extraction conditions were used: pH 9.5, 1/15 solid/liquid ratio, 35°C for yellow pea, desi and kabuli chickpeas, and pH 9.0, 1/10 solid/liquid ratio, 25°C for red and green lentils. UF experiments were performed with a 50kDa MWCO membrane with diafiltration (4X) at pH 6.0. The initial protein content of the pulses (16.7–24.8%, w/w) was concentrated nearly 4-fold. UF process generated concentrates with slightly higher protein contents (69.1–88.6%, w/w) compared to the IEP process (63.9–81.7%, w/w). Yields for both processes on a protein basis ranged from 50.3% to 69.1% (w/w). All concentrates exhibited good functional properties. However, functional properties varied to some extent as a function of the type of pulse and manufacturing process. For pH ranging from 1 to 3 and from 7 to 10, the red and green lentil concentrates were the most soluble (70–77%) and their UF concentrates were more soluble at all pH values studied compared to the IEP samples which was not the case for the pea and chickpea samples. Water holding capacity was highest for IEP-processed yellow pea and lowest for the UF-processed desi and kabuli chickpeas. Emulsifying properties and foam expansion were generally higher for the chickpea concentrates but they had less foam stability. Protein extracts from green lentils appeared to have the best gelling properties. The results highlight the technological potential of pulse protein extracts for food applications. [Copyright &y& Elsevier]