High Pressure Feed Research Articles

Highly plasticization-resistant Tröger’s base polymer–MOF mixed-matrix membranes for stable gas separation

The plasticization phenomenon, characterized by polymer chain swelling when exposed to highly soluble gas at high feed pressure, has been a major problem for polymer membranes. To address this, we prepared Tröger’s base (TB) polymer-based metal–organic framework (MOF) mixed-matrix membranes (MMMs), which are highly plasticization-resistant membranes. Three different highly porous MOF nanoparticles (ZIF-8, UiO-66-NH2, and MIL-101(Cr)) were prepared in small particle sizes. The corresponding MMMs were formed with a 30 wt% MOF loading to study the effects of MOF species, particle size, chemical functionality, and MOF–polymer interfacial interaction on gas-transport properties and plasticization behavior. The TB polymer-based MOF MMMs exhibited significantly higher H2 and CO2 permeabilities (fourfold to eightfold) than the TB polymer membrane owing to the porous nature and high gas adsorption capacity of the MOF. Additionally, the TB-based MOF MMMs, particularly the UiO-66-NH2 MMM, displayed exceptional CO2 plasticization resistance. This is attributed to the interfacial interaction of the strong hydrogen bonding between the amine group of the TB polymer and the amino group of UiO-66-NH2, as confirmed by small-angle X-ray scattering characterization. This TB polymer-based MOF MMM approach provides a feasible and effective route for enhancing gas-transport properties and CO2 plasticization resistance to achieve energy-efficient and stable gas separation.

Expanding interfacial polymerization for gas separation beyond water purification

Extending interfacial polymerization (IP) to gas separation is challenging due to microdefects in dry conditions, despite its attractive and straightforward processability. This study presents a systematic defect-tailoring approach for highly reproducible polyamide (PA) thin film composite (TFC) membranes with precise size-sieving ability. The approach combines highly porous polyethylene support, extended IP reaction time (60 min), and post-thermal/solvent treatments, resulting in a homogeneous PA selective layer. Particularly, isopropanol treatment removes less-reacted amine-rich monomers/oligomers and promotes PA network chain relaxation, enhancing molecular-sieving capability. The resulting PA TFC membrane exhibits a remarkable H2/CO2 selectivity of 24.8 (±3.1) and an H2 permeance of 13.6 (±1.8) gas permeation unit, surpassing the polymeric upper bound. It also ensures mechanical stability under high feed pressure and resistance to physical aging, highlighting its robustness. Additionally, universality is validated using different amine monomers. This systematic method provides a valuable framework for producing reproducible PA TFC membranes with exceptional gas separation performance, enabling practical implementation across industrial sectors.

Thermodynamic, economical and environmental performance evaluation of a 330 MW solar-aided coal-fired power plant located in Niger

The integration of solar thermal energy into a coal-fired power plant is one of the best ways to reduce the environmental impact of the latter linked to the release of carbon dioxide (CO2) into the atmosphere. In this paper, solar energy is used before the boiler, just after the first high-pressure feed water heater via a solar preheater (Water/Heat Transfer Fluid exchanger). It should be noted that in this study, there is no feed water heater displacement, and so the plant will operate in pure fuel-saving mode. To carry out an analysis of the integration of solar thermal energy in a coal-fired power plant, a 330 MW Solar Aided Coal Power Plant (SACPP) in northern Niger was studied. The results bring out that the annual solar energy production is 208 GWh, and solar energy can contribute up to approximately 15 % in the production of electricity. The considered SACPP significantly reduces the environmental impact of coal-fired power plants, leading to a reduction in CO2 emissions of around 381358 tons/year. In addition, the annual energy production cost from solar energy in the hybrid system is obtained as 0.0357 $/kWh and the investment payback period is around 12 months.

In-situ observation and quantification of membrane deformation in reverse osmosis, using optical coherence tomography

Deformation of the membrane can seriously hamper the performance of a reverse osmosis process. Currently, the most used approach to obtain detailed information on membrane deformation is by conducting membrane autopsy. However, ex-situ analysis can only observe irreversible deformation. In this study, optical coherence tomography (OCT) was introduced as method for in-situ 3D visualization and quantification of membrane and feed channel deformation during operation with varying transmembrane pressure (0–55 bar). In-situ monitoring of membrane surface geometry in a lab-scale flow-cell revealed the formation of specific patterns with ridges and valleys. The deformation became more pronounced with increasing applied pressure, due to membrane intrusion into the permeate spacer. The asymmetric structure of the permeate spacer causes a clear distinction in spatial distribution of ridges and valleys, depending on which side faces the membrane. Interestingly, membrane surface displacement increased linearly with TMP, with slope depending on spacer orientation (A vs B) and type (BW vs SW). Under pressure, we found the following displacements: Ridge – BW-A 1.7 ± 0.1 μm/bar, BW-B 1.9 ± 0.1 μm/bar, SW-A&B 1.5 ± 0.3 μm/bar; Valley – BW-A 3.2 ± 0.1 μm/bar, BW-B 2.7 ± 0.1 μm/bar, SW-A 1.7 ± 0.2 μm/bar, SW-B 1.8 ± 0.3 μm/bar. Measuring the membrane position under pressure revealed that the displacement involves the whole membrane-permeate spacer structure, i.e., the permeate spacer is also deformed. By alternating high and low feed pressure, we could distinguish between reversible and irreversible deformation. In-situ measurement of membrane deformation can contribute to understanding of pressure related performance and can serve as input for advanced modeling.

Performance Analysis and Techno-Economic Evaluation of Solar Energy Retrofitting for Coal-Fired Power Plant in Central Kalimantan Province

The power generation sector significantly contributes to climate change. Mitigation efforts are crucial to adhering to the global commitment to limit temperature increases below 2°C. One potential solution is retrofitting existing power plants with technologies that integrate renewable energy. This study explores the integration of solar energy into the operational processes of a coal-fired power plant in Central Kalimantan, replacing the extraction steam turbine in the high-pressure feed water heater No. 7. Using STEAG EBSILON for simulation, this research evaluates the power plant's performance before and after retrofitting in both power-boost (PB) and fuel-save (FS) modes under varying load conditions. The results demonstrate that thermal efficiency in both PB and FS modes increased by up to 2% compared to the base scenario. Specific fuel consumption decreased by 15.05 g/kWh in PB mode and 15.75 g/kWh in FS mode, leading to a reduction in coal consumption and CO2 emissions by 4.69% and 4.94% respectively. Additionally, the study observed that the solar percentage and solar-to-electricity efficiency increased as the load decreased. In FS mode, the solar electricity proportions at VWO, 100%, 75%, and 50% load rates were 5.23%, 5.53%, 7.76%, and 11.92%, respectively. The levelized cost of energy (LCOE) for solar electricity was calculated to be 431.82 IDR/kWh, with an expected investment return period of 5.87 years.

Application of deep learning modelling of the optimal operation conditions of auxiliary equipment of combined cycle gas turbine power station

Reasonable condition adjustment of the auxiliary machinery can optimize the operation performance of the Combined Cycle Gas Turbine (CCGT) power station. In this paper an optimization method for the operation control of the auxiliary equipment based on deep learning is proposed and applied to an F-class gas turbine generation unit. A database of the optimal operating conditions is established to achieve the best economic benefit based on the analysis of two years of historical operation data. The control optimization models are built using the machine learning algorithms including the Multi-Layer Perceptron (MLP), Supporting Vector Machine (SVM), Gaussian process regression and linear regression methods and their accuracy has been compared. The input parameters of these models consist of the load rate, the heating output and the ambient temperature, with the output parameters including the electrical currents for the mechanical draft cooling tower, the high pressure feed pump, the medium pressure feed pump and the condensate pump. The MLP model is designed with different network hidden layer structures and provides the highest calculation accuracy with the least average error of 1.82 %. Different training data sizes are compared and the optimal control trajectory is analyzed. The result can provide useful references for the optimization of auxiliary equipment operations.

One-Step Synthesis of Structurally Stable CO2-Philic Membranes with Ultra-High PEO Loading for Enhanced Carbon Capture

Membrane technology has been considered a promising strategy for carbon capture to mitigate the effects of increasing atmospheric CO 2 levels because CO 2 -philic membranes have demonstrated significant application potential, especially, for CO 2 /light gas separation. In this regard, poly(ethylene oxide) (PEO), which is a representative CO 2 -philic material, has attracted extensive research attention owing to its specific dipole–quadrupole interaction with CO 2 . Herein, we report a facile one-step synthesis protocol via the in situ polymerization of highly flexible polyethylene glycol to overcome the limitations of PEO, including high crystallinity and poor mechanical strength. The robust structure derived from intricate entanglements between short PEO chains and the polymer matrix enables an extremely high loading of linear polyethylene glycol (up to 90 wt%). Consequently, the separation performance easily surpasses the upper-bound limit. Moreover, the high structural stability allows for the concurrent increase of CO 2 permeability and CO 2 /light gas selectivity at high feed pressure (up to 20 bar). This study provides a promising strategy to simultaneously improve the toughness and gas separation properties of all-polymeric membranes, demonstrating significant potential for industrial carbon capture and gas purification.

Facile metal-ion infiltration into polyimide membranes with coordination crosslinking for efficient gas separation

We report a facile metal-ion infiltration method for engineering the properties of 6FDA-DAM:DABA (6FDA: 4,4′-(hexafluoroisopropylidene)diphthalic anhydride, DAM: 2,4,6-trimethyl-1,3-diaminobenzene, DABA: 3,5-diaminobenzoic acid; referred to as 6FDD) polyimide membranes. The 6FDD polyimide membrane samples were simply immersed in metal ion (copper, zinc, and cobalt) solutions of various concentrations (1 and 10 wt%) to obtain metal-ion-infiltrated 6FDD membranes. The metal ions and the carboxylate group of the 6FDD polyimide form a coordination bond, which can increase the d-spacing between the inter-polymer chain distances and reduce polymer chain mobility. The coordination between the metal ion and the carboxylated polymer chain enhances the mechanical properties of the polyimide membranes. The metal ion coordination provides not only increased stiffness but also high resistance to the breaking point under elongation. The metal ions were distributed uniformly across the entire 6FDD membrane without any noticeable defects, which indicated the effectiveness and simplicity of the proposed method, which can be applied to versatile membrane module types and conformations. The metal-ion infiltrated 6FDD membrane exhibited improved gas permeability compared to that of the pure 6FDD membrane because of the enhanced diffusivity coefficient resulting from the increased d-spacing. Particularly, the metal-ion-infiltrated 6FDD membranes exhibited significantly higher plasticization resistance because of a decrease in the normalized CO2 permeability at 750 psi compared to that of the pure 6FDD membrane. For example, the normalized CO2 permeability of the 10 wt% copper-ion-infiltrated 6FDD membrane increased by 120% but that of pure 6FDD membrane increased by 315%. This was because the metal–carboxylate group coordination strongly prevented relaxation of the polymer chain when it was exposed to plasticizing gases at high gas feed pressures.

Appealing sheath‐core spun high‐performance composite carbon molecular sieve membranes

AbstractCarbon molecular sieve (CMS) membranes are attractive candidates to meet requirements for challenging gas separations. The added ability to maintain such intrinsic properties in an asymmetric morphology with a structure that we term a “Pseudo Wheel+Hub & Spoke” asymmetric form offers new opportunities. For CMS membrane, specifically, the structure provides both selective layer support and low flow resistance even for high feed pressures and fluxes in CO2 removal from natural gas. This capability is unavailable to even rigid glassy polymers due to the much higher modulus of CMS materials. Combining precursor asymmetric hollow fiber formation and optimized pyrolysis creates a defect free CMS proof‐of‐concept membrane for this application. Facile formation of the sheath‐core spun precursor with a 6FDA‐DAM sheath and Matrimid® core also avoids the need to seal defects before or after the carbonization of the precursors. The composite CMS membrane shows CO2/CH4 (50 : 50) mixed gas feed with an attractive CO2/CH4 selectivity of 64.3 and CO2 permeance of 232 GPU at 35 °C. A key additional benefit of the approach is reduction in use of the more costly high performance 6FDA‐DAM in a composite sheath‐core CMS membrane with the “Pseudo Wheel+Hub & Spoke” structure.

Appealing sheath-core spun high-performance composite carbon molecular sieve membranes.

Carbon molecular sieve (CMS) membranes are attractive candidates to meet requirements for challenging gas separations. The added ability to maintain such intrinsic properties in an asymmetric morphology with a structure that we term a "Pseudo Wheel+Hub & Spoke" asymmetric form offers new opportunities. For CMS membrane, specifically, the structure provides both selective layer support and low flow resistance even for high feed pressures and fluxes in CO2 removal from natural gas. This capability is unavailable to even rigid glassy polymers due to the much higher modulus of CMS materials. Combining precursor asymmetric hollow fiber formation and optimized pyrolysis creates a defect free CMS proof-of-concept membrane for this application. Facile formation of the sheath-core spun precursor with a 6FDA-DAM sheath and Matrimid® core also avoids the need to seal defects before or after the carbonization of the precursors. The composite CMS membrane shows CO2 /CH4 (50 : 50) mixed gas feed with an attractive CO2 /CH4 selectivity of 64.3 and CO2 permeance of 232 GPU at 35 °C. A key additional benefit of the approach is reduction in use of the more costly high performance 6FDA-DAM in a composite sheath-core CMS membrane with the "Pseudo Wheel+Hub & Spoke" structure.

Fabrication of high-selective hollow fiber DD3R zeolite membrane modules for high-pressure CO2/CH4 separation

All-silica Decadodecasil 3 R (DD3R) zeolite membranes, possessing small pore size of 0.36 nm × 0.44 nm, have been attractive in CO2 removal from natural gas. In this work, hollow fiber DD3R zeolite membrane modules with membrane length of 40 cm and effective membrane area of 811 cm2 for each were successfully fabricated by ensemble synthesis strategy. Different membrane segments including that was grown on sealing glaze have similar thickness in the range of 4–6 μm. The ozone detemplation time of membrane unit was reduced by a half with the assistance of Teflon spiral column. The resulting membrane module exhibited a good CO2/CH4 separation selectivity (105) as well as a stage-cut of 25.7% at high feed pressure of 3.1 MPa. Effects of feed pressure, feed gas flow rate and permeate pressure on separation performance of the membrane module and concentration polarization were investigated extensively. When the feed gas flow rate was 2 L min−1, the retentate CO2 concentration was lowered to 9.45% and the CH4 loss was limited to 4.87% at the feed and permeate pressures of 3.1 MPa and 2 kPa. The concentration polarization effect became more serious at higher feed pressure or lower feed gas flow rate.

Low‐pressure plasticization of PEBAX 2533 membrane by carbon dioxide

AbstractPEBAX 2533 membrane is used to investigate plasticization by carbon dioxide (CO2) at low pressure. To reduce complex interaction caused by hydrostatic pressure and competitive sorption, a new experimental technique named the “Rest test” is presented. In the Rest test, the membrane is exposed to permeation of CO2 at 4 bar for 30 min and then put to rest for up to 12 h with residual CO2 after ventilation. When the membrane rests more than 9 h with residual CO2 after the permeation, the permeability increases by, at least, 50%. Permeation of CO2 is the prerequisite condition of permeability increase during the rest. Permeability increase in the Rest test is improved by permeate side purge and prolonged rest period. Fugacity and sorption of leftover CO2 during the rest are the main factors inducing the permeability increase, whereas the permeability increase is suppressed by higher feed pressure and longer CO2 permeation time, indicating the influence of hydrostatic pressure. The Rest test cannot increase the permeability of glassier PEBAX 1657. The findings and relevant factors suggest that low‐pressure plasticization during the rest is a potential source of the permeability increase.

Analisa kebocoran line warming up high pressure boiler feed pump menggunakan metode root cause and failure analysis di Pembangkit Listrik Tenaga Gas & Uap Grati

The reliability of the Grati Gas And Steam Power Plant equipment is highly maintained to support the operational readiness of the generation. The feed water system at the Grati Gas And Steam Power Plant is one of the most important factors, especially in the feed water pump equipment. One of the pumps that is highly reliable is the High Pressure Boiler Feed Water Pump which is used as a tool for supply feed water to the Heat Recovery Steam Generator. However, from the recap data of disturbances in the Grati Gas And Steam Power Plant, leaks often occur in the system, precisely in the line warming up which serves to provide flow to the standby High Pressure Boiler Feed Water Pump and comes from the backflow of the High Pressure Feed Water Header to the Discharge side of the pump. Analysis related to the leak is very necessary in order to minimize losses due to the occurrence of the disturbance using the Root Cause And Failure Analysis method to eliminate the main disturbance causing the leak. The research variables used include the independent variable: regulating the pump discharge opening, the dependent variable: flow rate and valve warming up opening and the controlled variable: standby pump temperature and pump operating temperature. By conducting a series of trials setting the discharge valve opening of the High Pressure Boiler Feed Water Pump starting from 80%, 85%, 90%, 95% and 100%. The results of these tests can be concluded that the greater the opening of the pump discharge valve, the higher the speed and flow rate, while the pump discharge pressure will decrease.

Simultaneous Production of Aromatics and COx-Free Hydrogen via Methane Dehydroaromatization in Membrane Reactors: A Simulation Study.

As an alternative route for aromatics and hydrogen production, methane dehydroaromatization (MDA) is of significant academic and industrial interest due to the abundance of natural gas resources and the intensive demand for aromatics and COx-free hydrogen. In the present work, a simulation study on MDA in membrane reactors (MRs) was performed with the aim of co-producing aromatics and COx-free hydrogen with a highly improved efficiency. The effects of various parameters, including catalytic activity, membrane flux and selectivity, as well as the operating conditions on the MR performance were discussed with respect to methane conversion, hydrogen yield, and hydrogen purity. The results show that catalytic activity and membrane flux and selectivity have significant impacts on CH4 conversion and H2 yield, whereas H2 purity is mainly dominated by membrane selectivity. A highly improved MDA is confirmed to be feasible at a relatively low temperature and a high feed pressure because of the hydrogen extraction effect. To further improve MDA in MRs by intensifying H2 extraction, a simple configuration combining a fixed-bed reactor (FBR) and an MR together is proposed for MDA, which demonstrates good potential for the high-efficiency co-production of aromatics and COx-free hydrogen.

Interface engineering in MOF/crosslinked polyimide mixed matrix membranes for enhanced propylene/propane separation performance and plasticization resistance

The energy required for propylene/propane (C3H6/C3H8) separation is enormous: ∼0.3% of global energy consumption. Membrane separation is gaining much attention as an alternative or supplement for the conventional distillation processes, although the separation abilities and stabilities of current polymer membranes remain insufficient to meet industrial requirements. Herein, we propose a novel strategy to integrate the diamino crosslinking of polyimide (6FDA-DAM) membranes and the fabrication of their mixed matrix membranes (MMMs) to engineer the interfacial compatibility between filler and matrix. Crosslinking conditions for the 6FDA-DAM matrix are optimized for C3H6/C3H8 separation, and their MMMs were fabricated by incorporating UiO-66 (U) or UiO-66-NH2 (UN) fillers. After crosslinking the MMM precursors, detailed characterization results of the filler-matrix interfaces, which include morphological, spectroscopical, thermal, and mechanical analyses, indicate that the UN-incorporated MMMs display enhanced interfacial compatibility compared with their counterpart (i.e., the U-incorporated ones). Ultimately, the UN-incorporated MMMs showed significantly enhanced C3H6/C3H8 separation performances by surpassing both pure-gas and mixed-gas upper bounds. Besides, the MMM exhibited excellent plasticization resistance against the high feed pressure (5 bar) with high C3H6/C3H8 mixed-gas selectivity (23.7) and modest C3H6 permeability (6.3 Barrer), demonstrating its potential for use in industrial applications.

Enrichment of spent SF6 gas by zeolite membranes for direct reuse in gas-insulated switchgear units

Zeolite membranes have attracted considerable attention in the separation industry owing to their high separation selectivity and permeance. However, their industrial applications have been hindered owing to a lack of case studies focusing on their commercialization. Herein, MFI and SAPO-34 zeolite membranes were employed to purify spent SF6 gas taken from a gas-insulated switchgear (GIS). This study demonstrated that separation by a single zeolite membrane produced ultrapure SF6 gas (>99.7 %) satisfying the reuse guidelines for GIS units. This level of purity is difficult to achieve using polymeric membranes due to the plasticization effect. The synthesized MFI membrane exhibited high N2 permeance with ∼ 2,000 gas permeation units (GPU) at 2 bar and low N2/SF6 selectivity (<50), whereas the SAPO-34 membranes exhibited the opposite trends, i.e., high N2/SF6 selectivity (>500) and relatively low permeance (<600 GPU at 2 bar). Interestingly, the MFI membrane system effectively enriched the SF6 gas, while lower feed pressures achieved by decreasing the feed flows were required for the SAPO-34 membranes to achieve the same purity. Changes in the feed pressure led to corresponding changes in the membrane separation performance, and the concentration polarization increased at high feed pressures. A MFI membrane area of ∼ 0.088 m2 was sufficient to purify the entire spent SF6 gas produced by GIS units at 145 kV in 6 h; this indicates an opportunity to realize compact SF6 enrichment systems. Thus, considering the high separation performance and the small size of the separation system, MFI membranes represent a promising option for the industrial purification of spent SF6 gas from GIS units.

Challenges, Opportunities and Future Directions of Membrane Technology for Natural Gas Purification: A Critical Review.

Natural gas is an important and fast-growing energy resource in the world and its purification is important in order to reduce environmental hazards and to meet the required quality standards set down by notable pipeline transmission, as well as distribution companies. Therefore, membrane technology has received great attention as it is considered an attractive option for the purification of natural gas in order to remove impurities such as carbon dioxide (CO2) and hydrogen sulphide (H2S) to meet the usage and transportation requirements. It is also recognized as an appealing alternative to other natural gas purification technologies such as adsorption and cryogenic processes due to its low cost, low energy requirement, easy membrane fabrication process and less requirement for supervision. During the past few decades, membrane-based gas separation technology employing hollow fibers (HF) has emerged as a leading technology and underwent rapid growth. Moreover, hollow fiber (HF) membranes have many advantages including high specific surface area, fewer requirements for maintenance and pre-treatment. However, applications of hollow fiber membranes are sometimes restricted by problems related to their low tensile strength as they are likely to get damaged in high-pressure applications. In this context, braid reinforced hollow fiber membranes offer a solution to this problem and can enhance the mechanical strength and lifespan of hollow fiber membranes. The present review includes a discussion about different materials used to fabricate gas separation membranes such as inorganic, organic and mixed matrix membranes (MMM). This review also includes a discussion about braid reinforced hollow fiber (BRHF) membranes and their ability to be used in natural gas purification as they can tackle high feed pressure and aggressive feeds without getting damaged or broken. A BRHF membrane possesses high tensile strength as compared to a self-supported membrane and if there is good interfacial bonding between the braid and the separation layer, high tensile strength, i.e., upto 170Mpa can be achieved, and due to these factors, it is expected that BRHF membranes could give promising results when used for the purification of natural gas.

Pre-combustion CO2 capture using amine-based absorption process for blue H2 production from steam methane reformer

A novel pre-combustion CO2 capture process using methyl diethanolamine with piperazine (MDEA/PZ) was investigated for the production of blue H2 from a steam methane reformer (SMR). A sensitivity analysis was performed at various operating parameters (such as MDEA or PZ concentration, flash drum pressure, CO2 loading in a lean-amine solvent, and CO2 removal efficiency) using a validated rate-based model. The energy consumption to capture CO2 from SMR gas at 21 bar was evaluated, including the compression energy (up to 30 bar) for the dehydration of captured CO2. For 90% and 95% CO2 removal efficiency, reboiler duties were 1.318 GJ/tonCO2 and 1.364 GJ/tonCO2, and CO2 compression works were 11.673 kW/molCO2 and 11.615 kW/molCO2. The results indicated more than 40% lower reboiler duty than the energy consumption of conventional CO2 capture processes in post-combustion. Subsequently, artificial neural network model (ANN)-based optimization using the differential evolution method was performed. The developed ANN-based optimization suggested the possibility of additional 0.3 % reduction in the equivalent work at a low computational cost. The results indicated that the developed pre-combustion CO2 capture for a SMR was highly competitive in industrial applications. Moreover, the H2 mixture produced at 21 bar is beneficial for a H2 recovery unit because of no need for additional compression energy. Therefore, the MDEA/PZ-based absorption process can effectively contribute to centralized or semi-central blue H2 production from a SMR. This study provides a guideline for the feasible optimization and control of the CO2 absorption process at high feed pressures.

Downscaling reverse osmosis for single-household wastewater reuse: towards low-cost decentralised sanitation through a batch open-loop configuration

Abstract There is a significant demand for water recycling in low-income countries. However, wastewater infrastructure is primarily decentralised, necessitating the development of affordable household-scale reclamation technology. In this study, a batch open-loop reverse osmosis (RO) system is therefore investigated as a low-cost clean water reclamation route from highly saline concentrated blackwater. In a single-stage configuration, increasing feed pressure from 10 to 30 bars improved selective separation at water recovery exceeding 85%, whereas lower cross-flow velocity improved product recovery, reducing specific permeate energy demand from 21 to 4.8 kWh m−3. Rejection achieved for total phosphorous (99%), chemical oxygen demand (COD, 96%), and final pH (8.7) of the RO permeate was compliant with the ISO30500 reuse standard for discharge. However, the rejection of total nitrogen in the RO permeate was non-compliant with the reuse standard due to the transmission of low-molecular weight (MW) uncharged organic compounds. It is suggested that rejection may be improved by increasing feed pressure to rebalance selectivity but may also be controlled by reducing fluid residence time (storage) to constrain the hydrolysis of urea. The economic analysis identified that a high-pressure 1812 element cost of ∼US$30 meets the sanitation affordability index of US$0.05 capita−1 day−1. However, the unit cost of a high-pressure feed pump must be reduced to ∼US$500 to obtain an affordable system cost. These unit costs can be achieved by manufacturing 1812 elements at economies of scale, and by adopting pumping solutions that have been developed for other applications requiring high pressures and low flows. Overall, our findings suggest that RO in the batch open-loop configuration has the potential to deliver affordable and safe water production from blackwater in a decentralised (single-household) context.

High-pressure CO2 permeation properties and stability of ceramic-carbonate dual-phase membranes

CO 2 permeation properties and stability of ceramic-carbonate dual-phase membranes at high pressures/temperatures are critical to their CO 2 separation and membrane reactor applications, but such data are not available in the literature. This work aims to study the effect of high transmembrane pressure on CO 2 permeation flux and the stability of molten carbonate in the dual-phase samarium-doped ceria (SDC) and molten-carbonate (MC) membranes. Dead-end porous SDC tubular supports were made by a cold isostatic press (CIP)/sintering method with a low porosity (below 7%), and gas-tight SDC-MC membranes were prepared by direct infiltration of molten lithium and sodium carbonate mixture into SDC pores, with a MC volume fraction less than 7%. CO 2 permeation/separation tests were performed on the SDC-MC membranes using feed gas of equal molar CO 2 /N 2 mixture at feed pressures up to 15 atm and sweep gas of helium at 1 atm. CO 2 permeation flux for the SDC-MC membranes depends logarithmically on feed/permeate CO 2 pressure ratio in 660–810 o C. The temperature dependence of CO 2 permeation shows activation energy of 30 kJ/mol. Due to the small MC volume fraction and hence low effective carbonate conductivity, CO 2 permeation of the SDC-MC membranes is dominated by the carbonate ionic conduction in the MC phase. The SDC-MC membranes remain in the same structure, morphology, and gas-tightness after CO 2 separation tests at high feed pressures and temperatures, showing high stability of SDC-MC membranes for high-temperature, high-pressure separation and chemical reaction applications. • Strong ceramic-carbonate dual-phase membranes can be made by the cold isostatic press method. • High-pressure CO 2 permeation flux depends logarithmically on feed/permeate CO 2 partial pressure ratio controlled by carbonate ionic conduction. • Samarium-doped ceria-molten carbonates membranes are stable at high pressures/high temperatures.