Spiral Membrane Modules Research Articles

Effects of fluid flow on the rate limiting for CO2 capture by an AEEA containing membrane

The efficiency of CO2 capture using a hollow fiber membrane containing 2-(2-Aminoethylamino) ethanol (AEEA) from the emission gas in the Integrated Gasification Combined Cycle (IGCC) was investigated by density functional theory and fluid dynamics. A reaction path for CO2 sorption to AEEA involving two H2O molecules with three – proton transfer was found to give the low barrier of the reaction due to 6 intermolecular hydrogen bonds which make the transition state structure more stable. The activation energy in the reaction path for CO2 sorption to AEEA was 7.11 kcalmol−1 which is approximately 10 kcalmol−1 lower than that involving one H2O molecule with two – proton transfer discussed in our previous study (Higashino et al., 2023). Since the activation energy is much lower than those in the other reaction paths we have investigated, it can occur much more frequently than others when sufficient moisture is maintained in the membrane. The estimated reaction rate k = 3.407 × 108 s−1 indicates that CO2 becomes carbamate by reaction with AEEA as soon as reaching the surface of the membrane, and thus, CO2 attachment to AEEA cannot be the rate limiting. Since flow in the hollow fiber membrane can be laminar, simulated CO2 permeance for the temperature of 358 K and the pressure of 2.4 MPa has a range from 10−10 to 10−9 m3 (STP) m−2s−1Pa−1, which is a few orders smaller than that for the flat sheet membrane, flow over which is turbulent, i.e.10−8 to 10−7 m3(STP) m−2s−1Pa−1 (Higashino et al., 2023). Overall, the reaction rate of CO2 attachment to AEEA is sufficiently large, and hence, any one of mass transfer of CO2 induced by turbulence (turbulent flow), molecular diffusion of CO2 from feed gas to the membrane surface (laminar flow), and molecular diffusion of bicarbonate (HCO3-) from the feed side to the permeate side in the membrane can be the rate limiting depending on which type of membrane, e.g. a flat sheet membrane module, a spiral membrane module, a hollow fiber membrane contactor, etc., is used for CO2 capture.

Concentrated Buffalo Whey as Substrate for Probiotic Cultures and as Source of Bioactive Ingredients: A Local Circular Economy Approach towards Reuse of Wastewaters

Waste reduction and reuse is a crucial target of current research efforts. In this respect, the present study was focused on providing an example of local investment in a simple process configuration that converts whey into value-added compounds and allows recovery of a clean water stream. In particular, buffalo milk whey obtained during mozzarella manufacturing was ultrafiltered in-house on spiral membrane modules (20 kDa), and the two obtained fractions, namely the retentate and the permeate, provided by the dairy factory, were further processed during this work. The use of an additional nanofiltration step allowed the recovery of high-quality water to be reused in the production cycle (machine rinsing water within the facility) and/or in agriculture, also reducing disposal costs and the environmental impact. The ultrafiltration retentate, on the other hand, was spray-dried and the powder obtained was used as the main substrate for the cultivation of Lactobacillus fermentum, a widely studied probiotic with anti-inflammatory, immunomodulatory and cholesterol-lowering properties. In addition, the same sample was tested in vitro on a human keratinocytes model. Resuspended concentrated whey powder improved cell reparation rate in scratch assays, assisted through time-lapse video-microscopy. Overall these data support the potential of buffalo whey as a source of biologically active components and recyclable water in the frame of a local circular economy approach.

Integrated Membrane Processes (EDR-RO) for Water Reuse in the Petrochemical Industry

The objective of this work was to apply a hybrid process, including electrodialysis reversal (EDR) and reverse osmosis (RO) to the treatment of petrochemical wastewater in order to obtain process water for reuse. A water balance was carried out to defne the main water consumers and the process step that could receive the produced water. Additionally, toxicity assays were performed to evaluate the removal of toxic compounds after EDR and RO processes. Different operation parameters in the EDR and RO processes were investigated to enhance the membrane performance. The EDR assays were performed in a pilot plant, with 300 ion-selective membranes and an area of 0.096 m2 for each membrane. The process conditions were: electrical potential of 150 V and 250 V, dilute flow rate at 600 L.h-1 and 1,000 L.h-1, concentrate flow rate maintained at 200 L.h-1, with 25% recirculation and operation in series and parallel modes. The RO assays were conducted in pilot equipment, with a polyamide spiral membrane module with a membrane area of 7.2 m2. Assays were performed at 8 bar, varying the reject flow in each experiment as follows: 150, 300, 450 and 600 L.h-1. The EDR-RO hybrid system presented a removal rate above 90% for most physicochemical parameters from the wastewater, generating a process water without toxicity.

Increasing water recovery rate of membrane hybrid process on the petrochemical wastewater treatment

Abstract The objective of this work is to increase the recovery of water through a Reverse Osmosis + Electrodialysis Reversal (RO-EDR) hybrid process, where the EDR is used to recover water from the reject produced by the RO technology. The wastewater used in the experiments was collected in a petrochemical industry, located in southern Brazil, after conventional treatment (biological and stabilization ponds). The RO tests were carried out in a pilot equipment, having a spiral membrane module, with a membrane area of 7.2 m2. For the EDR tests, it was used a pilot equipment, with 300 ion-selective membranes, with a total membrane area of 28.8 m2. The results show that the application of EDR technology was adequate for the treatment of the RO reject, obtaining a removal efficiency above 90% for chlorides and alkalinity. The recovered water comply with standards for reuse in cooling towers. In addition, the full recovery of the treated water was satisfactory, reaching a recovery rate of 87.3%, turning the EDR-RO hybrid process as a prominent one.

Application of reverse osmosis to petrochemical industry wastewater treatment aimed at water reuse

PurposeThe purpose of this paper is to apply reverse osmosis (RO) to the treatment of industrial wastewater from a large petrochemical complex in Southern Brazil, in order to verify the conditions of liquid effluent reuse and improve them, especially to reduce the consumption of natural water by some production structures such as boilers and cooling towers.Design/methodology/approachThe petrochemical wastewater was submitted to pretreatment using a sand filter and activated carbon filters. Tests were conducted using RO equipment with a production capacity of 0.25 m3h−1 composed of a spiral membrane module with a membrane area of 7.2 m². Pressures of 8, 12 and 15 bar were applied with reject flow maintained constant at 10 Lm−1.FindingsThe experiment results indicated optimum RO performance since more than 90 percent extraction was obtained for most of the compounds present in the petrochemical wastewater.Originality/valueBy checking the aspects involved, as well as providing some relevant considerations about, this study promotes the application of RO to get a satisfactory water reuse in similar industries, thereby decreasing both the volume of water extracted from wellsprings and the amount of wastewater released into water bodies.

Study on seawater nanofiltration softening technology for offshore oilfield polymer solution preparation

Nanofiltration (NF) is suitable for softening seawater and providing permeates with excellent quality for oilfield water injection. However, the industrial application of aqueous polymer solution prepared by NF softened seawater for oilfield polymer flooding has not been reported yet. In this work, a pilot-scale ultrafiltration (UF)–NF integrated membrane system (IMS) has been investigated as a method of removing divalent ions from seawater and providing softened water for oilfield polymer flooding. The performance of the selected NF 4040 spiral membrane module was investigated under different operating conditions. In addition, the performance of the NF membrane module at high system recovery was also investigated to simulate the practical situation. Finally, NF permeation waters were used to prepare HPAM polymer solutions to evaluate the possibility of preparing polymer solution with NF permeation water for polymer flooding in offshore oilfield. The results showed that, with the properly selected NF membrane, the operation factors and the order of membrane modules had little effect on its permeate quality, which could keep more than 90% removal rate for Ca2+ and Mg2+. And NF2 membrane modules could provide good quality permeate for preparing polymer solution for polymer flooding in offshore oilfield.

Influence of the Adopted Pretreatment Process on the Critical Flux Value of Batch Membrane Processes

This work deals with an experimental investigation on the effect of different pretreatments on the critical flux of both an ultrafiltration and a nanofiltration membrane process, applied at pilot scale, on the purification of an olive washing wastewater. Two pretreatments were considered: flocculation and biofiltration. First, the flocculation process was optimized, taking into account two different coagulants and varying the dosage and the mixing procedure. The same wastewater was treated by a biological filter. The obtained pretreated solutions were then processed by using wound spiral membrane modules of ultrafiltration and nanofiltration to determine the critical flux for each membrane process. For both the examined membrane processes the critical flux value was around 40% higher when the flocculation pretreatment was applied.

Concentration of xylose reaction liquor by nanofiltration for the production of xylitol sugar alcohol

Xylitol, a five-carbon sugar alcohol, is used commercially as a natural sweetener in several food products including soft drinks and confectionery. Xylitol is produced by catalytic dehydrogenation of xylose, an intermediate sugar compound, which is extracted from sugar cane bagasse, corncobs or rice husk. The reaction liquor of xylose contains 1.5–2% of d-xylose besides water as the major constituent. The current process of evaporation for concentration of xylose reaction liquor can be effectively replaced by the more economical nanofiltration technique. Pilot scale nanofiltration (NF) experiments were carried out using a polyamide (PA) spiral membrane module having 300 molecular weight cut-off (MWCO) and 1 m 2 effective area. At a feed pressure of 20 bar, xylose was concentrated from 2 to 10% at a reasonably high average flux of 24 l/(m 2 h) and rejection of >99% which indicated negligible losses of the sugar in the permeate. The efficiency of NF was compared with another membrane methods, reverse osmosis (RO) for concentration of xylose reaction liquor. Effect of fouling on NF membrane performance and life span as well as methods for cleaning the membrane for restoring flux and rejection were evaluated. An economic comparison between nanofiltration and evaporation for a feed capacity of 1 m 3/h of xylose reaction liquor showed that NF capital investment was 75% of the evaporator installation cost, whereas the operating cost for NF was only 0.04 times the evaporation cost.

Concentration of xylose reaction liquor by nanofiltration for the production of xylitol sugar alcohol

Xylitol, a five-carbon sugar alcohol, is used commercially as a natural sweetener in several food products including soft drinks and confectionery. Xylitol is produced by catalytic dehydrogenation of xylose, an intermediate sugar compound, which is extracted from sugar cane bagasse, corncobs or rice husk. The reaction liquor of xylose contains 1.5–2% of d-xylose besides water as the major constituent. The current process of evaporation for concentration of xylose reaction liquor can be effectively replaced by the more economical nanofiltration technique. Pilot-scale nanofiltration experiments were carried out using a polyamide (PA) spiral membrane module having 300 molecular weight cut-off and 1 m 2 effective area. At a feed pressure of 20 bar, xylose was concentrated from 2 to 10% at a reasonably high average flux of 24 l/m 2 h and rejection of >99% which indicated negligible losses of the sugar in the permeate. Effect of fouling on membrane performance and life span as well as influence of operating parameters such as feed flow rate and trans-membrane pressure was evaluated. An economic comparison between nanofiltration and evaporation is presented for a feed capacity of 1000 kg of the solution.

Extraction of organic acids from kiwifruit juice using a supported liquid membrane process

In order to extract or remove organic acids from kiwifruit juice, we evaluated their separation and transport rates through supported liquid membranes (SLMs). The liquid membrane consisted of an organic solution composed of a carrier (Aliquat 336/Alamine 336) and a linear alcohol (oleyl alcohol) and was loaded on a microporous polypropylene support (commercial grade Celgard 2500/2400). These SLMs were evaluated (i) in a batch cell to determine the permeability and (ii) in a continuous spiral membrane module to study the effects of various process parameters – flow of feed and strip solutions, membrane composition, recycling mode of operation and kiwifruit juice at natural pH. It was observed that there exists an optimum for each system: pH 2.5– 3.0 for Alamine 336/oleyl alcohol and pH 4.5 for Aliquat 336/oleyl alcohol. At this pH the flux rates of citric acid and malic acid was greater (6–8 times) than that of quinic acid. The flux rates decreased (greatly for citric acid) with the flow rate of feed and strip solutions and increased (considerably for citric acid) with the SLM composition . The recycling of feed and strip solutions significantly improved the removal efficiency. The SLM system retained its performance over a period of a few days. The SLM process allowed extraction of the above three organic acids (ascorbic acid was removed in trace amounts) from kiwifruit juice at a rate of a few percent (5%) in a single-pass processing.

New pretreatment systems using membrane separation technology

Removal of suspended solids from raw water is a basic technology in water treatment to prevent rapid growth of cake layers. The conventional technology used for removal consists of coagulation, sedimentation and filtration systems. However, when the quality of raw water changes, the suspended solids leak into filtered water, often fouling subsequent RO membrane modules. If we can substitute a conventional pretreatment system with membrane separation technology, the subsequent RO fouling will be eliminated and stable operation will become possible. At the same time the system will also be simplified. However, there have been no appropriate membrane modules applicable for pretreatment systems, and very few attempts have been made to replace the coagulation, sedimentation and filtration process with membrane systems.We have succeeded in developing a new spiral membrane module which can directly feed the raw water containing suspended solids. Due to its construction with through water channels, this module is applicable to the direct feeding of the raw water containing a large quantity of suspended solids, promising the possible development of its new applications. However, the requirement for the application of this membrane separation technology to water treatment is the reduction of operational cost, that is, an increase in the filtration flux of the membrane module.We studied how to increase the filtration flux from three viewpoints: promotion of turbulent flow in raw water, coagulation effect and membrane backwashing. As a result, we found that intermittent membrane backwashing combined with turbulent flow promotion is an effective means to maintain high filtration flux of the membrane module.

Neutralization dialysis for desalination

Neutralization dialysis is an energy-saving process consisting in the exchange of the ions of the salts from a feed solution which circulates between cation-exchange and anion-exchange membranes for equivalent amounts of H + and OH − ions supplied through the respective membranes from acid and alkali solutions. The experiments show the effect of various physico-chemical process parameters on the rate and degree of desalination of model salt solutions and the possibility to efficiently desalinate multicomponent natural mixtures. It should be pointed out that by a 10-fold increase in the concentration of acid and alkali the flow of the mineral ions can be enhanced 3-fold. It is shown that a high degree of desalination can be reached also at a high salt concentration. The experimental data obtained by modelling the desalination conditions of a real system using a spiral membrane module reveal a similarity between neutralization dialysis and electrodialysis desalination processes.