Membrane Process Design Research Articles

On the thermodynamic properties of hydrolysed urine: Experimental data, predictive and correlative models for the design of concentrative urine treatment technologies

Source-separated urine contains the potential for water, nutrient and energy recovery. During the recovery of such resources, urine treatment technologies undergo temporal changes in the thermodynamic properties of urine. To inform the design of thermal, membrane and electrochemical urine treatment processes, this study experimentally measured and modelled the thermophysical properties of synthetic hydrolysed urine (vapour pressure, osmotic pressure, density, and electrical conductivity) across temperature and concentration profiles using two approaches: predictive thermodynamic equations based on an ionic speciation model and correlative modelling. The vapour pressure and osmotic pressure were accurately predicted to 14 wt% for the predictive model, within an error of 0.30% and 0.46%, respectively, while the correlative model based on the experimental data from this study demonstrated an error of <1% for both parameters across the whole range of salt concentrations and temperatures (4.5 to 32.2 wt%; 333 to 373 K). The predictive and correlative models for density and electrical conductivity showed adequate agreement with the experimental data, where error did not exceed 2.12% and 1.2%, respectively, across the entire range of concentrations and temperatures.The value of the models for the development of sustainable urine treatment technologies was demonstrated by their application to determine the optimum heating surface area of a urine evaporator and the energy requirements of a reverse osmosis process.

A perspective on data-driven screening and discovery of polymer membranes for gas separation, from the molecular structure to the industrial performance

Abstract In the portfolio of technologies available for net zero-enabling solutions, such as carbon capture and low-carbon production of hydrogen, membrane-based gas separation is a sustainable alternative to energy-intensive processes, such as solvent-based absorption or cryogenic distillation. Detailed knowledge of membrane materials performance in wide operative ranges is a necessary prerequisite for the design of efficient membrane processes. With the increasing popularization of data-driven methods in natural sciences and engineering, the investigation of their potential to support materials and process design for gas separation with membranes has received increasing attention, as it can help compact the lab-to-market cycle. In this work we review several machine learning (ML) strategies for the estimation of the gas separation performance of polymer membranes. New hybrid modelling strategies, in which ML complements physics-based models and simulation methods, are also discussed. Such strategies can enable the fast screening of large databases of existing materials for a specific separation, as well as assist in de-novo materials design. We conclude by highlighting the challenges and future directions envisioned for the ML-assisted design and optimization of membrane materials and processes for traditional, as well as new, membrane separations.

Membrane process design for biohydrogen purification with simultaneous CO2 capture: Feasibility and techno-economic assessment

In this work, a membrane separation process is designed and optimized to purify dark fermentative biohydrogen by removing CO2. A CO2-selective PVAm-based nanocomposite membrane was selected considering its high CO2/H2 separation performance and unique features suitable for the process. We tested the membrane performances under the separation conditions to provide a more accurate simulation basis. Several design scenarios were investigated. A two-stage process with a recycle stream is determined as the optimal design, in which the specific cost for purifying H2 to 99.5 vol% with H2 loss of <10% reaches only 0.156 $/Nm3. The techno-economic feasibility study of biohydrogen purification with simultaneous CO2 capture was also performed through an alternative design by introducing a 3rd-stage using the same membrane or an H2-selective membrane. Adding a 3rd-stage membrane can capture and purify CO2 as a side product of various purities, which further decreases the H2 loss, leading to additional economic benefits.

Gas Separation Membrane Module Modeling: A Comprehensive Review.

Membrane gas separation processes have been developed for diverse gas separation applications that include nitrogen production from air and CO2 capture from point sources. Membrane process design requires the development of stable and robust mathematical models that can accurately quantify the performance of the membrane modules used in the process. The literature related to modeling membrane gas separation modules and model use in membrane gas separation process simulators is reviewed in this paper. A membrane-module-modeling checklist is proposed to guide modeling efforts for the research and development of new gas separation membranes.

MATHEMATICAL MODEL OF MEMBRANE MODULE FOR SOLVENT RECOVERY FROM SOYBEAN OIL MISCELLA

A mathematical model was developed to predict the performance of solvent recovery process in the extraction of vegetable oils. The model is oriented to mathematical programming and to be used in the optimization of a biorefinery superstructure. Experimental data published were recompiled for the PVDF-10SI membrane. For the case study, the mathematical model gives much more conservative design results than if the design was made only with punctual experimental data. To concentrate miscella from 25% wt to 38% wt of oil, the required membrane area is 275.22 m2 for the mathematical model, while the design through punctual experimental data gives a membrane area of 224.23 m2. Besides, the mathematical model allows evaluating the separation performance of each of the intervening compounds through their permeabilities. This is an important contribution, since the results obtained using punctual experimental data are not accurate enough for membrane process design in the oils desolventizing.

Synchronous Design of Membrane Material and Process for Pre-Combustion CO2 Capture: A Superstructure Method Integrating Membrane Type Selection

Membrane separation technology for CO2 capture in pre-combustion has the advantages of easy operation, minimal land use and no pollution and is considered a reliable alternative to traditional technology. However, previous studies only focused on the H2-selective membrane (HM) or CO2-selective membrane (CM), paying little attention to the combination of different membranes. Therefore, it is hopeful to find the optimal process by considering the potential combination of H2-selective and CO2-selective membranes. For the CO2 capture process in pre-combustion, this paper presents an optimization model based on the superstructure method to determine the best membrane process. In the superstructure model, both CO2-selective and H2-selective commercial membranes are considered. In addition, the changes in optimal membrane performance and capture cost are studied when the selectivity and permeability of membrane change synchronously based on the Robeson upper bound. The results show that when the CO2 purity is 96% and the CO2 recovery rate is 90%, the combination of different membrane types achieves better results. The optimal process is the two-stage membrane process with recycling, using the combination of CM and HM in all situations, which has obvious economic advantages compared with the Selexol process. Under the condition of 96% CO2 purity and 90% CO2 recovery, the CO2 capture cost can be reduced to 11.75$/t CO2 by optimizing the process structure, operating parameters, and performance of membranes.

Two-stage membrane-based process utilizing highly CO2-selective membranes for cost and energy efficient carbon capture from coal flue gas: A process simulation study

Membrane technology for CO2 capture has become an attractive strategy due to its cost and energy efficiency and low materials costs. In the past decade, membrane-based process designs for post-combustion power plant CO2 capture have been developed, utilizing existing highly CO2-permeable membranes with relatively low CO2/N2 selectivity (<50), and have obtained reasonably economic carbon capture. However, few membrane-based process designs were proposed for moderate to highly CO2-selective membranes (CO2/N2 selectivity of 50–300, and >300, respectively), which have vastly emerged in recent years, such as various facilitated transport membranes (FTMs). Herein, we proposed a two-stage membrane-base process design targeting economic carbon capture from coal-fired flue gas. This process design features the utilization of highly CO2-selective membranes for one-stage CO2 enrichment to 95% dry-base purity in the first stage and recycle of the remaining CO2 by a highly CO2-permeable membrane in the second stage, in order to achieve economic CO2 capture with 90% capture rate and >95% CO2 product purity. Through an integration-iteration membrane model and the Aspen Plus process simulation, a sensitivity study of operating pressures (feed and permeate pressures) and membrane properties (CO2 permeance and CO2/N2 selectivity) was conducted. Critical CO2/N2 selectivity of 300–400 was found for the highly CO2-selctive membranes to meet the demand for cost and energy efficient results. The lowest possible membrane area of 4.8 × 105 m2 and fractional energy of 19.3% were obtained, which is comparable to or even more attractive than reported membrane-based process designs. This work provides a new membrane process design option for highly CO2-selective membranes and gives insights on the influence of membrane performance and operation condition.

Inadequacy of current approaches for characterizing membrane transport properties at high salinities

Cost optimal design of osmotic membrane processes requires an accurate estimate of membrane transport parameters across their full operational range. However, standard approaches for estimating these parameters rely on empirical methods, the accuracy of which remains unquantified as a function of temperature, salinity, and measurement error. Herein, we present a systematic accuracy analysis of previously developed methods for estimation of membrane transport properties in reverse osmosis, high-pressure reverse osmosis, forward osmosis, pressure retarded reverse osmosis, and osmotically assisted reverse osmosis. We use a Monte Carlo approach to sample the full range of feasible membrane water permeabilities, salt permeabilities, structural parameters, and operating conditions for these processes. These material and process parameters are then incorporated into a physical transport model for each process. Our analysis shows that the statistical uncertainty of current empirical methods for estimating membrane parameters increases by 5 times from low-salinity to high-salinity conditions. The result of this work demonstrates that empirical methods are inadequate for precisely estimating membrane transport properties at high salinity and highlight a critical need for the development of statistically validated higher accuracy methods.

Analysis and optimal design of membrane processes for flue gas CO2 capture

Membrane separation technology is a potential low-cost flue gas CO2 capture technology to cope with increasing CO2 content in the atmosphere. This paper analyzes the effects of different driving force generation strategies, membrane separation performance and water vapor on operating energy consumption and CO2 capture cost. Then membrane processes are optimized and designed under a wide range of separation requirements. The energy consumption of feed compression combined with permeate vacuum is the lowest when the stage cut is larger than 33.8%, but from the perspective of CO2 capture cost, the vacuum operation is suitable for membranes with high CO2 permeance and moderate selectivity, such as the CO2 permeance above 4000 GPU and the CO2/N2 selectivity below 100, to reduce the investment cost of membrane-related equipment. Since only improving the CO2/N2 selectivity results in an enlarged membrane area and consequently limits the reduction of CO2 capture cost, the development trend of CO2 permeance with increasing CO2/N2 selectivity is proposed to restrain the expansion of membrane area. The water vapor in flue gas can improve the mass transport driving force of CO2 and reduce the membrane area and the capture cost. For water-facilitated membranes, it is recommended to use segmented humidification to replenish the water vapor content of the residue side, especially for the membrane process with a high stage cut, such as the first stage of a two-stage membrane process. Finally, the optimal membrane process and operating pressure under different separation targets, specifically 50–95% dry basis CO2 purity and 50–90% CO2 recovery rate, are obtained by the techno-economic analyses.

Synchronous Design of Membrane Material and Process for Pre-Combustion Co2 Capture: A Superstructure Method Integrated Membrane Material Selection

Synchronous Design of Membrane Material and Process for Pre-Combustion Co2 Capture: A Superstructure Method Integrated Membrane Material Selection

Membrane Science and membrane Engineering for a sustainable industrial development

• Membrane Engineering contribute to a sustainable industrial development satisfying the requirements of innovative equipment and process methods. • Membrane operations are a dominant technology in seawater desalination and in the future years might play a significant role for minerals production. • MBR’s leadership role in wastewater treatment is well recognized. • Modeling contribute to the knowledge-based design of membrane materials and processes. Membrane Engineering has an important and recognized role in different areas of strategic importance as water stress, global warming, energy production, raw materials depletion, artificial hybrid organs, neurosciences, technical textile, etc. Satisfying the requirements of innovative processes and equipment design, i.e., smaller, cleaner, more energy-efficient technology, will help to achieve substantial improvements in chemical and any other manufacturing and processing aspects. Membrane-based technology satisfies these requirements and its potential has been broadly recognized in the last few years. It can replace conventional energy-intensive separation techniques providing reliable options for sustainable industrial growth. This work aims to update on the contributions of Membrane Engineering to sustainable processes. We present an overview of the Membrane Engineering approaches successfully employed in water treatment and the production of raw materials, in modeling of membrane material and processes, and membrane reactors.

A comprehensive overview of dual-layer composite membrane for air (O2/N2) separation

The separation of air (O2/N2) via a polymeric membrane has recently piqued the interest of academic researcher as well as the industrial sector. Because of its remarkable characteristics, the polymeric membrane has emerged as one of the innovative and fast growing technology. However, two major problems faced by membrane technology, which hinder its growth in the commercial sector are, 1): The trade-off between permeability and selectivity. 2): Maintaining physical and chemical structural stability in a long-term commercial scale process. Recent advancements in membrane material, structural, and process design have enabled the development of dual-layer composite (DLC) membranes. This concept combines the benefits of both thinner mixed matrix membranes (MMMs) based active layer and porous support substrate. Due to these properties, the membrane exhibits higher perm-selectivity with enhanced mechanical strength as compared to single layer polymeric membrane. This review article mainly focused on the developmental progress of DLC membrane throughout the years. In which membrane structural details, selection criteria, fabrication methodologies, application [e.g., air (O2/N2) separation] were critically reviewed. In addition, challenges arising in the DLC membrane production and future prospects for the development of these membranes were also thoroughly discussed in this literature. This creates a paradigm for future research in the commercial development of these membranes for the air (O2/N2) separation process, which can be utilized in both medical and industrial sectors. [Formula: see text]

Characterization and modelling of soluble microbial products in activated sludge systems treating municipal wastewater with special emphasis on temperature effect.

Soluble microbial products (SMP) classified as utilization-associated products (UAP) and biomass-associated products (BAP) are the predominant foulants determining fouling in tertiary filtration. However, the exact mechanisms of BAP and UAP generation when treating real wastewaters under cold temperatures remain unrevealed. This paper presents the first study linking biological processes and SMP formation when treating real wastewaters through a combination of bioprocess modelling and advanced SMP characterization. Further, the impact of low operating temperatures on SMP production which has received relatively little attention was studied in detail. The use of liquid chromatography-organic carbon detection (LC-OCD) revealed a significant increase in protein and polysaccharide concentrations in the treated effluents as temperature decreased with a more sensitive impact on polysaccharides. The generation of SMP from biomass decay (BAP) and substrate utilization (UAP) was derived from the LC-OCD data on the basis of protein and polysaccharide mass balances. UAP and BAP yields were estimated as the ratios of the observed generation rates to the rates of substrate utilization and endogenous decay respectively, which both declined as temperature increased. A strong correlation was observed between temperature and BAP/UAP yields whereas the generation of BAP was more temperature sensitive than UAP. Such process modelling can be employed to assist with the optimization of the design and operation of membrane processes when treating wastewaters under challenging conditions like low temperature.

Import Substitute for Production of Ultrapure Water by Membrane Integrated Process for Medical and Biotechnological Applications

The present invention discloses an inexpensive import substitute compact design of low-cost membrane process for the production of ultrapure water for dialysis and medical applications in different fields like pathological laboratories, biochemical analysis, sterilization and sanitation, dental and optical lens cleansers. The ultrapure water of demineralization (DM) process is related to the cascaded high- flux and high-selective membrane system for hyper permeation which is operated under the pressure of 3-7 kg/cm2 to generate DM water with total dissolved solids (TDS) of 0−2 ppm. The DM water system is designed for a capacity in the range of 25–60 L/h capacity and its salient features include compact design of the membrane assembly with higher effective membrane area per unit volume to ensure higher DM water recovery at relatively lower pressure compared to the existing reverse osmosis (RO) membrane system. The process pertaining to the present invention is more economical, low maintenance and highly effective compared to the conventional demineralization and more expensive demineralization membrane units currently available in the market. The configuration of the membrane modules adapted in the present invention is simple, easy to operate and useful for several biotechnological, biochemical, medical, and industrial applications shown as graphical sketch figure1.

Polymer genome–based prediction of gas permeabilities in polymers

Abstract Predicting gas permeabilities of polymers a priori is a long-standing challenge within the membrane research community that has important applications for membrane process design and ultimately widespread adoption of membrane technology. From early attempts based on free volume and cohesive energy to more recent group contribution methods, the ability to predict membrane permeability has improved in terms of accuracy. However, these models usually stay “within the paper”, i.e. limited model details are provided to the wider community such that adoption of these predictive platforms is limited. In this work, we combined an advanced polymer chemical structure fingerprinting method with a large experimental database of gas permeabilities to provide unprecedented prediction precision over a large range of polymer classes. No prior knowledge of the polymer is needed for the prediction other than the repeating unit chemical formula. In addition, we have incorporated this model into the existing Polymer Genome project to make it open to the membrane research community.

Process-integrated design of a sub-ambient membrane process for CO2 removal from natural gas power plants

This paper proposes an advanced sub-ambient membrane process that applies an improved CO2/N2 selectivity under cold temperatures for CO2 removal from a natural gas combined-cycle power plant. The use of a large excess of combustion air in a natural gas power plant results in a relatively diluted CO2 exhaust gas, typically by 3–4%, which makes it difficult to achieve an energy-efficient CO2 capture. The sub-ambient membrane process using exhaust gas recirculation and/or selective exhaust gas recirculation is designed to concentrate the CO2 from 4 to 6–10%. In addition, the heat integration of liquefied natural gas (LNG) regasification not only provides a nearly free cold energy source for producing a cold processing environment, it also maximizes the full potential of the heat recovery. Among the different membrane designs proposed, an integrated process using all design options demonstrates the lowest CO2 capture cost at $ 57/tCO2, which is a 55.1% reduction in capture costs, and a 70.1% decrease in parasitic load compared to an early configuration. A sensitivity analysis was conducted to understand the impact of the membrane performance, namely, the CO2 permeance and CO2/N2 selectivity, on the process design and economics of the CO2 capture process considered herein, through which guidelines for the development of membrane materials and a conceptual insight into the design and optimization of a membrane-based capture process can be obtained.

Advances in Membrane Materials and Processes for Desalination of Brackish Water

This review aims to succinctly summarize recent advances of four key membrane processes (e.g., reverse osmosis (RO), forward osmosis (FO), electrodialysis (ED), and membrane distillation (MD)) in membrane materials and process designs, to elucidate the contributions of these advances to the steadfast growth of brackish water membrane desalination processes. With detailed analyses and discussions, the ultimate purpose of the review is to shed light on the future direction of brackish water desalination using membrane processes. Brackish water has widely varying particulate matter and boron contents, posing great risks of membrane fouling and excessive boron levels to the membrane desalination processes. Recent advances in these four membrane processes largely focus on improving fouling resistance, boron rejection, water flux, and energy efficiency. Aquaporin membranes and thin-film composite polyamide membranes incorporated with nanoparticles exhibit excellent performances for RO and FO, whereas super-hydrophobic membranes prove their great potentials for MD. While recent advances in RO and ED process designs are orientated towards membrane fouling prevention by exploring respectively novel energy-saving membrane-based pre-treatment and reversal operation, recent studies on FO and MD are centered on reducing the energy costs by advancing the fertilizer-drawn concept and utilizing waste heat. Membrane processes are dominating brackish water desalination, and this trend is hardly to change. Membranes based on nanoparticles and other novel materials are deemed the next membrane generation, and innovative membrane process designs have demonstrated great potentials for brackish water desalination. Nevertheless, further works are needed to scale up these novel membrane materials and designs.

Reverse Osmosis: Use or not to use?

Air, water and soil very important for our living but urbanization and industrialisation , have polluted all of it .None of the is left undisturbed but the condition of water is more dreadful as we use it for drinking purpose too. We have numerous methods to purify water and one of them is Reverse Osmosis.Reverse Osmosis (RO) is a water purification technology that uses a semipermeable membrane to remove ions, molecules and larger particles from drinking water. RO removes inorganic minerals which are unhealthy and healthy too3. Improvement in RO technology including advanced membrane material, module and process design, and energy recovery has led to cost reduction which in turn gaining interest to its commercial as well as household applications. In this article, the applications of RO, its advantages, and limitations are being discussed especially related to health.

A Study on the Relationship Between the Boundary Flux Parameters and Membrane Process Requirements

The boundary flux concept permits to describe the fouling behaviour of membrane systems as a function of the operating time. The method relies on a set of equations that is possible to integrate in time, thus permitting to evaluate the separation process outcome and performances. This study focuses on the relationship between the membrane area requirements and specific parameters of the boundary flux concept on different membrane systems characterized by different waste feed streams and operating conditions. The target of the analysis was to identify which parameters of the boundary flux equations are the most influent one on the membrane area requirements. The knowledge of the relevant parameters can strongly assist membrane process designers to minimize the capex of the developed plants. The study was performed on many different systems, available in literature, and at different operating conditions. In order to avoid the triggering of irreversible fouling, the operation must be performed in sub-boundary operating conditions, and as a consequence, the condition of the permeate flux Jp equal to the boundary flux Jb must be met at the end of operation. Summarizing briefly the findings, it was possible to observe that the membrane area requirements are minimized for higher pure water membrane permeability values (w) for recoveries up to 75% Ymax, but then, in the range up to 90% Ymax, to achieve the same target, it appears to be more important to have higher Jb values. In other words, in those systems characterized by VRF (volume recovery factor) less than 4, high membrane permeabilities appears advantageous for the choice, even in presence of some extent of fouling. This appears not to be the case for those systems targeting higher VRF values: in this case, high Jb values must be achieved. Since the value of Jb depends on many parameters, such as T, Re and other physical-chemical characteristics, the minimization of the membrane area requirements requires the proper design of the membrane process, pre-treatment steps and operating conditions choice.

A novel green solvent alternative for polymeric membrane preparation via nonsolvent-induced phase separation (NIPS)

The membrane market has grown rapidly over the past several decades, supported by continuous improvements in membrane performance, module and process design, and fouling control. However, such growth will be unsustainable with current membrane fabrication methods that employ significant amounts of toxic solvents (e.g., N-methylpyrrolidone, dimethylacetamide, and dimethylformamide), thereby producing billions of liters of contaminated wastewater each year. A possible solution is to identify greener alternatives with appropriate properties that are compatible with conventional polymers. In this work, we employed a novel green solvent, Rhodiasolv PolarClean®, that is less toxic than current solvents and eco-friendly, while exhibiting the necessary properties to be employed as a solvent for membrane preparation via the nonsolvent-induced phase separation (NIPS) method. Rhodiasolv PolarClean® has been successfully applied to membrane preparation for water desalination and reclamation by ultrafiltration (UF) and nanofiltration (NF) with conventional polymers, including polysulfone (PSF), polyethersulfone (PES), and cellulose acetate (CA). The UF membranes prepared from PES/Pluronic F127 and PSF/polyvinylpyrrolidone exhibited pure water permeabilities greater than 314.5 ± 57.8 L m−2 h−1 bar−1 and tensile strength 3.78 ± 0.12 MPa with BSA rejection of 98.1 ± 0.4%. Cellulose acetate membrane used for NF applications demonstrated pure water permeability of 1.5 ± 0.25 L m−2 h−1 bar−1 with NaCl and MgCl2 rejection of 85.1 ± 5.7% and 93.2 ± 4.7%, respectively. The performance of the prepared membranes was competitive with current state-of-the-art membranes across all applications, indicating immediate applicability to improving the sustainability of membrane fabrication processes.