Reverse Osmosis Research Articles

Effect of environmentally friendly reverse osmosis scale inhibitors on inorganic calcium carbonate scale

A highly efficient and environmentally friendly composite scale inhibitor was developed using sodium carboxymethyl cellulose (CMC-Na) and polyepoxysuccinic acid (PESA). The PESA:CMC-Na=1:3 optimum ratio was observed with a maximum enhancement factor of 1.81. The film flux attenuation rate was reduced from 24.98 % to 6.2 % at optimal operational condition (concentration 80 mg/L, initial pH 7) for actual mine water treatment. X-ray diffraction (XRD) and scanning electron microscopy (SEM) analysis results showed that the addition of the compound scale inhibitor transformed the calcium carbonate scale from calcite to vaterite with looser and more porous structure. The molecular dynamics simulation results demonstrate that composite scale inhibitor had a higher binding energy with calcite than that of PESA, CMC-Na, resulting in the restrained formation of calcite. This study provides a new technical idea for the application of scale inhibitor to improve the treatment efficiency of mine water by reverse osmosis.

Simulation of a Passive Osmosis-Integrated Electrolyzer for Seawater Electrolysis

The requirement for extremely pure water in electrolysis, combined with the abundant presence of seawater, has prompted extensive research into the creation of direct seawater electrolysis technology for decades [1]. However, these efforts have had limited success due to other limiting issues that arise, including competition with the chloring evolution reaction, increased membrane resistance, corrosion of electrode materials and electrode scaling due to the presence of multivalent cations. To avoid these issues, seawater is typically first desalinated using reverse osmosis, but that comes with additional energy cost. Therefore, our project has proposed a new reactor that integrates passive osmosis (extracting fresh water from seawater) with electrolysis.In this presentation, we will discuss the operation of the osmosis-integrated electrolyzer and show theoretical predictions of the osmotic pressure differential and water flux/velocity profiles under different conditions. The numerical model that will be presented was applied to three different cell designs that have been physically developed. The first cell consists of two anion exchange membranes (AEMs) with two side chambers containing KOH and a middle chamber containing Sodium Chloride (NaCl). The second cell has KOH in one outer compartment and H2SO4 in the other. The central compartment containing NaCl is separated from KOH compartment by an AEM and the H2SO4 compartment by a cation exchange membrane (CEM). The third cell eliminates the central compartment and allows the osmosis to occur outside of the cell.The simulation results show that by increasing the concentration of KOH and H2SO4 in the side chambers for all three models, the amount of water transferred from the middle chamber, containing of NaCl to the side chambers increases. The simulation results were validated by experiments (Figure 1). In addition, the model is able to quantify the transport of ions in the system, including chloride ions through the AEM. Lastly, the mass transfer model is integrated with an electrochemical model where an anode and cathode are added to the system to consume the water that is transported through the membranes.Reference:[1] M. A. Khan, T. Al-Attas, S. Roy, M. M. Rahman, N. Ghaffour, V. Thangadurai, S. Larter, J. Hu, P. M. Ajayan, and M. G. Kibria, “Seawater electrolysis for hydrogen production: a solution looking for a problem?” Energy & Environmental Science, 14, 4831 (2021). Figure 1

Investigating Water and Ion Transport in a Novel Cell Design for Seawater Electrolysis

With increasing concerns about the climate change associated with the carbon dioxide emission from utilizing traditional fuels, hydrogen has become a preferred low-carbon energy carrier. For hydrogen to truly be a clean source of energy, it must be produced from a renewable source of energy through water electrolysis. Theoretically, for each kilogram of hydrogen to be produced 9 kg of high-purity water need to be consumed, thus the enormous use of clean water for H2 production may worsen the shortage of fresh water in many parts of the world.Owing to its abundance, seawater has received great attention in the field of hydrogen production; however, there are many challenges associated with the direct use of seawater for electrolysis. In traditional systems, the seawater is first deionized by reverse osmosis (RO) before being fed to the electrolyzer. The RO system adds complexity to the system and requires energy to be expended for the deionization. Therefore, modern systems have aimed to directly electrolyze seawater, but this comes with it own issues including electrode corrosion, scaling from the ions present in saline water, environmental concerns associated with competitive chlorine evolution reaction, and increased membrane resistance limiting the overall performance of saline water electrolysis. Several strategies have been proposed to overcome these challenges including developing selective electrocatalysts, blocking strategy, pH buffer strategy, etc.This project sought to overcome the issues with direct seawater utilization by designing a cell that is driven by osmotic separation, but does not require an external power source. In this device, high concentration acid/base concentrations are maintained in contact with another compartment containing seawater. The acid/base reservoirs act as draw solutions, taking water passively from seawater due to their differences in osmotic pressure. This talk will focus on the cell design and operation, and include both experimental and modeling results. The rate of water transport with various cell operating configurations was quantified alongside the rate of chloride ion crossover through the anion exchange membrane. New methods for chloride mitigation were explored – including cell operating conditions, membrane design and absorption. Multiple cell configurations will be shown and strategies for reducing the cell operating voltage will be discussed.

Enhancing bioethanol conversion from straw by a novel circulation promotion method

Crop straw, an inedible and abundant agricultural by-product, can be used for bioethanol production. However, ethanol conversion from straw is a series of complex processes and has encountered issues, which cause considerable restriction to the production of straw ethanol. Herein, the bioethanol conversion process was innovated. Ethanol as a reverse osmosis membrane accelerant was investigated to enhance the removal of inhibitors to increase ethanol production during conversion process. The results indicated that membrane accelerant used here could reduce the inhibitor retentions by 39.3 %–69.2 %. Then, an original innovation integrated method for the whole process of straw ethanol conversion was developed. The integrated method could increase 26.8 % the production of straw ethanol compared to the membrane process without an accelerant. A preliminary cost accounting indicated that the integrated method was economically feasible when total ethanol output exceeded 14000 kg. This study represents for the first time a circulation promotion method based on the whole process of straw ethanol conversion. The results showed that the integrated method was capable of effective conversion of straw ethanol.

(Invited) Curvature-Enhanced Hydrophobicity: A Counter-Intuitive Strategy for Efficient Electroreduction of Nitrate into Ammonia

The electrochemical upcycling of nitrate (NO3 −) to ammonia (NH3) holds promise for synergizing both wastewater treatment and NH3 synthesis. Efficient stripping of gaseous byproducts (NH3, H2, and N2) from electrocatalysts is crucial for continuous and stable electrochemical reactions. This study evaluated a layered electrocatalyst structure using copper (Cu) dendrite to enable a high curvature and hydrophobicity and achieve a stratified liquid contact at the gas-liquid interface of the electrocatalyst layer. As such, gaseous product desorption or displacement from electrocatalysts was enhanced due to the separation of a wetted reaction zone and a non-wetted zone for gas-transfer. Consequently, this electrocatalyst structure yielded a 1.9-fold boost in per active site activity compared to that with a low curvature and high hydrophilic counterpart. Moreover, a high NH3 Faradaic efficiency of 90.9 ± 2.3% was achieved with nearly 100% NO3 − conversion. This high-curvature hydrophobic Cu dendrite was further integrated with a gas-extraction membrane, which demonstrated outstanding NH3 yield from the real reverse osmosis retentate brine. Figure 1

Graphene Oxide Surface Modification of Reverse Osmosis (RO) Membrane via Langmuir-Blodgett Technique: Balancing Performance and Antifouling Properties.

The reverse osmosis water treatment process is prone to fouling issues, prompting the exploration of various membrane modification techniques to address this challenge. The primary objective of this study was to develop a precise method for modifying the surface of reverse osmosis membranes to enhance their antifouling properties. The Langmuir-Blodgett technique was employed to transfer aminated graphene oxide films assembled at the air-liquid interface, under specific surface pressure conditions, to the polyamide surface with pre-activated carboxylic groups. The microstructure and distribution of graphene oxide along the modified membrane were characterized using SEM, AFM, and Raman mapping techniques. Modification carried out at the optimal surface pressure value improved the membrane hydrophilicity and reduced the surface roughness, thereby enhancing the antifouling properties against colloidal fouling. The flux recovery ratio after modification increased from 65% to 87%, maintaining high permeability. The modified membranes exhibited superior performance compared to the unmodified membranes during long-term fouling tests. This membrane modification technique can be easily scaled using the roll-to-roll approach and requires minimal consumption of the modifier used.

Techno-economic assessment and transient modeling of a solar-based multi-generation system for sustainable/clean coastal urban development

To ensure the health of vulnerable coastal ecosystems, a transition to sustainable energy solutions is essential. Environmentally friendly systems powered by renewable sources offer not only a reduction in pollution but also the adaptability needed for a flexible and resilient energy future. This study proposes and comprehensively evaluates an integrated solar-based system designed to meet the daily needs of coastal cities. The proposed system incorporates key components such as dual-loop power cycles, parabolic trough solar collectors, liquefied natural gas (LNG) regasification, reverse osmosis, and proton exchange membrane electrolysis. To optimize energy utilization, the inclusion of a thermoelectric generator (TEG) is considered, harnessing the thermal gradient among the LNG stream and the power cycle fluid. We conduct transient modeling, incorporating comprehensive scenarios that account for both thermal and economic aspects. The performance evaluation of the system focuses specifically on coastal regions, with San Francisco serving as a case study. The dynamic simulation results demonstrate the capability of the integrated system in fulfilling the urban needs for one year, delivering 1,134,207 cubic meters of potable water and generating 11,306 MWh of electricity. Financial analysis reveals that the solar unit accounts for over 46 % of the total cost, with an hourly cost rate of $69.61. The levelized cost of electricity is predicted at 4.61 cents/kWh, while the levelized cost of water is calculated at 30.54 cents/m3. These findings provide valuable insights into the cost-effectiveness and competitive advantage of the system in terms of energy and water production.

Analyzing the Performance of Reverse Osmosis Membranes After the Cleaning Process: Case study Performed at PT. XYZ.

Analyzing the Performance of Reverse Osmosis Membranes After the Cleaning Process: Case study Performed at PT. XYZ.

Thermal integration process for waste heat recovery of SOFC to produce cooling/H2/power/freshwater; cost/thermal/environmental optimization scenarios

High-temperature fuel cells (HT-FCs) indeed hold significant promise for enhancing energy systems' efficiency and environmental sustainability. Consequently, there is growing interest in exploring and developing innovative strategies to optimize the integration of heat recovery processes with HT-FC technology. The current research presents an innovative and environmentally friendly poly-generation unit that integrates advanced subprocesses to generate essential products. These final products include electricity, refrigeration, pure water, and hydrogen. This study signifies a significant step towards sustainable and efficient energy production while meeting diverse needs for different utilities. The design unit incorporates a novel modified dual ejector-based organic flash cycle, reverse osmosis water purification, and a water electrolyzer for hydrogen extraction, all integrated with a high-temperature solid oxide fuel cell. Energy, exergy, economic, and environmental (4E) analysis is conducted to thoroughly evaluate the proposed plan. Furthermore, a comprehensive parametric analysis and sensitivity study are performed to pinpoint the key design parameters of the poly-generation unit. To attain the optimal operational status of the poly-generation unit, a three-objective NSGA-II optimization technique is employed to fine-tune the system's performance within the exergy-cost-environmental framework. This approach aims to strike a balance between maximizing efficiency, minimizing costs, and reducing environmental impact for sustainable operations. In addition, a net present value analysis spanning a 20-year timeframe was conducted to assess the profitability of the devised unit. Based on the findings, it is evident that the sensitivity index of the fuel cell operating temperature carries substantial importance, registering a notable value of 0.60. Additionally, the optimization outcomes reveal the system's enhanced performance metrics: an exergetic efficiency of 41.11 %, a unit cost of 58.96 $/GJ, and a carbon dioxide emission reduction rate of 418 kg/MWh. Also, the unit's payback period is shortened from 11.33 years to 8.817 years. Moreover, it improved the unit's sustainability index and net present value, raising them from 1.544 to 4.98 M$ to 1.66 and 7.38 M$.

Recent progress in green thin film membrane based materials for desalination: Design, properties and applications

The urgent need for sustainable solutions to address freshwater scarcity has encouraged significant research interest in green thin film membrane-based materials (GTFM) for desalination applications. This review paper comprehensively examines recent progress in these innovative membranes' design, properties, and applications. Emphasizing environmental sustainability and efficiency, various fabrication techniques such as electrospinning, layer-by-layer assembly, and template synthesis are discussed for their role in tailoring membrane structures at the nanoscale. The review highlights the importance of incorporating eco-friendly materials, such as biopolymers, natural extracts, and nanocellulose, in membrane formulations to enhance biodegradability and reduce environmental impact. Furthermore, the paper investigates the crucial properties of green film membranes, including permeability, selectivity, mechanical strength, and fouling resistance. Additionally, the review explores recent advancements in functionalization strategies, such as surface modification and incorporation of nanomaterials, to enhance membrane properties and address specific desalination challenges. The applications of green thin film membranes across various desalination technologies, including reverse osmosis, nanofiltration, and forward osmosis, are thoroughly examined. Moreover, the review discusses emerging trends and future directions in green thin film membrane research, such as multifunctional membranes, hybrid systems, and integrated desalination processes. In summary, this review provides valuable insights into the design principles, fundamental properties, and diverse applications of GTFM-based materials for sustainable desalination, paving the way for the development of next-generation water purification technologies.

Hydrophilic modification of feed spacer and its impacts on antifouling performance of reverse osmosis membrane

AbstractFeed spacers improve mixing and mass transfer in membrane modules. However, they also lead to foulant deposition in the vicinity of the spacer surface. In this paper, two hydrophilic monomers, namely, acrylic acid (AA) and 2‐hydroxyethyl methacrylate (HEMA), are respectively coated on the surface of a commercial feed spacer via a plasma‐enhanced chemical vapor deposition (PECVD) method. The resulting modified spacers are then evaluated alongside with a reverse osmosis (RO) membrane for its solute rejection, water permeability, and antifouling properties. Results show that the surface hydrophilicity of feed spacers has been enhanced upon the AA and HEMA deposition. During filtration test, the HEMA‐modified spacer demonstrates higher flux recovery rate (94.17%) and salt rejection (95.78%) for the RO membrane. In contrast, the membrane with the unmodified spacer only shows 89.44% and 92.46%, respectively. Additionally, the membrane with the HEMA‐modified spacer has a thinner fouling layer (200 nm) compared to the unmodified spacer (700 nm). The HEMA‐coated spacer outperforms all the tested spacers, demonstrating that feed spacer modification with a hydrophilic monomer via the PECVD method can effectively reduce membrane fouling.

Metamodeling life cycle assessment to explore interactions in the water-energy nexus of desalination processes

The relationships within the Energy-Water nexus are inherently complex, necessitating sophisticated methods to optimize and manage these interactions effectively. Metamodeling emerges as a crucial technique in abstracting these complex relationships into a manageable analytical form. This study adopts a systematic approach to construct Life Cycle Assessment (LCA) metamodels, aimed at examining the interactions within the water-energy nexus of various desalination technologies. A critical aspect of the developed methodology is the selection of sampling points that align with LCA scenarios through a tailored designed experiment (DoE) model. These scenarios, which include Reverse Osmosis (RO), Electrodialysis (ED), and Multi-Effect Distillation (MED), are evaluated using a set of indicators the Energy-Water nexus, across tradeoff nexus policies. The results signify the impact of considering the Energy-Water Nexus on optimizing desalination processes, compared to evaluating energy and water metrics independently. In policies where nexus considerations were not integrated—focusing solely on cumulative energy or exclusively on water footprint—the RO with Wind Turbine (RO[WT]) scenario emerged as the optimal solution. This configuration consumed 7.540 MJ and 1.654 m³ of water and a carbon footprint of 0.719 kg CO2eq per cubic meter of desalinated water. Conversely, policies that incorporate a nexus approach favor the adoption of MED with Thermal Solar (MED[TS]) scenario. Characterized by its moderate energy consumption of 2.226 MJ, and a water footprint of 2.226 m³, per cubic meter. These findings illustrate the critical role of employing Energy-Water Nexus frameworks through metamodeling in minimizing the environmental impacts associated with desalination processes.

4E analysis and multi-objective optimization of a novel multi-generating cycle based on waste heat recovery from solid oxide fuel cell fed by biomass

The present study optimizes a novel developed cycle including solid oxide fuel cell (SOFC) fed by synthesis gas produced from biomass as well as gas turbine (GT), supercritical carbon dioxide cycle (SCO2), transcritical carbon dioxide cycle (TCO2), Organic Rankine Cycle (ORC), thermoelectric generator (TEG), and reverse osmosis (RO)- based desalination. Energy, exergy, exergoeconomic and exergoenvironmental analyses on the developed cycle were investigated. Multi-objective optimization was carried out using of Genetic algorithm using generated power and exergy destruction as objective functions. Sankey diagram data indicate that afterburner holds the highest portion of the total exergy destruction 46.5% (692.24 kW), followed by SOFC which is 20.48% (304.51 kW). Moreover, optimization results showed that the total net power, first and second laws of thermodynamic efficiencies increased by 2.6%, 0.96% and 0.83%, respectively, while exergy destruction decreased by 1%. Furthermore, such a power increase (18.53 kW) using the freshwater produced by RO leads to daily production of 17040 liters of drinking water. According to the exergoeconomic analysis, the minimum flow value pertains to GT at a value of 0.0119 $/GJ, while the TCO2 turbine has the highest value which is 0.2867 $/GJ. The system product cost rate and exergy destruction cost rate reached 27.0353 $/h, and 10.7012 $/h, respectively. In the case of the exergoenvironmental one, the maximum environmental impact is related to the SCO2 turbine 0.0212 Pts/GJ, while SOFC has the lowest (0.0002 Pts/GJ). The system product environmental impact and exergy destruction were achieved at optimum values of 2.7503 $/h, and 4.1576 ×10-7 $/h, respectively.

Inverse design of V-shape feed spacer for batch and semi-batch reverse osmosis

In recent years, batch and semi-batch reverse osmosis (RO) processes have received wide attention because of their internal staging feature. However their performance is severely compromised by salt retention induced by incomplete flushing, which leads to elevated salt concentration, uplifted peak pressure, and extra power consumption. Herein we adopt transient three-dimensional computational fluid dynamics to systematically analyze the effect of the V-shape feed spacer geometries on hydrodynamics and mass transfer characteristics. After a sensitivity analysis of all geometric parameters, a heuristic optimization framework is proposed for inverse design of the feed spacer. Using the optimized feed spacer, flushing efficacies after one displacement volume are 0.936, 0.962, 0.969 and 0.974 respectively for one, three, five and seven membrane elements connected in series (whereas 0.884, 0.926, 0.942 and 0.952 for commercial spacers), which help to mitigate membrane scaling and fouling. Moreover, the optimized spacer has a pressure drop per meter 73 % lower than that of the commercial spacer. If used in conjunction with high permeability membranes, batch RO and semi-batch RO could save 29.9 % and 24.1 % specific energy consumption relative to conventional one-stage seawater RO.

Evaluation of the Performance of Micro–Nano Bubbles to Control the Simultaneous Inorganic and Colloidal Foulings in Reverse Osmosis

Evaluation of the Performance of Micro–Nano Bubbles to Control the Simultaneous Inorganic and Colloidal Foulings in Reverse Osmosis

Incorporation of OA-APTES-MWCNTs into PS/PVP membranes for VMD desalination: Membrane composition optimization via Box–Behnken method

The hydrophobicity of the membrane is paramount in membrane distillation (MD). In this study, novel hydrophobic oleic acid-3-aminopropyltriethoxysilane-functionalized multi-walled carbon nanotubes (OA-APTES-MWCNTs) were successfully synthesized and incorporated into polystyrene (PS)/polyvinylpyrrolidone (PVP) membranes as nanofillers to obtain modified mixed matrix membranes (MMMs) for vacuum membrane distillation (VMD) process. FTIR spectroscopy and TEM micrographs confirmed the successful synthesis of OA-APTES-MWCNTs. The synthesis membrane-VMD performance relationship was explored by statistically analyzing the effects of PS, PVP, and OA-APTES-MWCNTs concentrations in the dope solution using response surface methodology (RSM) with Box-Behnken design (BBD). BBD results showed that increasing any of the three factors in the membrane composition lowers water flux but with different intensities. NaCl rejection increases with PS and peaks with PVP and OA-APTES-MWCNTs concentrations. The optimal membrane composition was found to be 25 wt% PS, 0.731 wt% OA-APTES-MWCNTs, and 1.568 wt% PVP, achieving 99.00 % NaCl rejection and 12.34 LMH water flux. Adding OA-APTES-MWCNTs improved hydrophobicity, porosity, and surface roughness and thus water flux and NaCl rejection, but reduced mechanical strength compared to the PS (25 wt%)/PVP (1.568 wt%) membrane. These enhancements are critical for improving the efficiency and effectiveness of the VMD process.

Scaling in reverse osmosis seawater desalination: Mechanism and prevention—A literature review

Scaling in reverse osmosis seawater desalination: Mechanism and prevention—A literature review

Assessment and characterization of solid and hazardous waste from inorganic chemical industry: Potential for energy recovery and environmental sustainability

Rapid global urbanization and economic growth have significantly increased solid waste volumes, with hazardous waste posing substantial health and environmental risks. Co-processing strategies for industrial solid and hazardous waste as alternative fuels highlight the importance of integrated waste management for energy and material recovery. This study identifies and characterizes solid and hazardous industrial wastes with high calorific values from various industrial processes at Nirma Industries Limited. Nine types of combustible industrial wastes were analyzed: discarded containers (W1), plastic waste (W2), spent ion exchange resins from RO plants (W3), sludge from effluent treatment in soap plants (W4), glycerine foot from soap plants (W5), rock wool puff material (W6), fiber-reinforced plastic waste (W7), spent activated carbon (W8), and spent cartridges from reverse osmosis plants (W9). Physical characterization, proximate and ultimate analysis, heavy metal concentration evaluation, and thermogravimetric analysis were conducted to assess their properties, revealing high calorific values exceeding 2500 kcal/kg. Notably, W1 and W2 exhibited the highest calorific values (∼10,870 kcal/kg), followed by W6 and W8 (∼6000 kcal/kg) and W9 (∼8727 kcal/kg). Safe heavy metal levels are safe, and high calorific values support the prospects of energy recovery and economic and environmental benefits, reducing landfill reliance and enhancing sustainable waste management.

A novel design of multilevel disk-type axial flux eddy current heating (AFECH) device: A sustainable approach for feed water heating in reverse osmosis desalination

A novel design of multilevel disk-type axial flux eddy current heating (AFECH) device: A sustainable approach for feed water heating in reverse osmosis desalination

Performance evaluation of MBR-RO technology for domestic wastewater treatment

Abstract This study was carried out to evaluate the treatment efficiency of domestic wastewater using Membrane Bioreactor combined Reverse Osmosis (MBR-RO) technology. The optimal hydraulic retention time (HRT) of the MBR was studied at various HRT value of 1h, 4h, and 8h. The MBR-RO reactor was then operated at optimal HRT for domestic wastewater treatment. The research result showed that the MBR has an optimal HRT of 4h. The removal efficiency of TSS, COD, BOD, TN, and TP in the MBR was 100%, 99.57%, 100%, 73.33%, and 94.41%, respectively. The MBR-RO system can completely remove organic and nutrient pollutants from wastewater with the removal efficiency was 100% for TSS, COD, BOD, TN, and TP. Consequently, the MBR-RO effluent meets the Vietnam regulation standard of QCVN 08:2015/BTNMT and QCVN 01-1:2018/BYT. Research results show the potential of applying MBR-RO membrane technology for domestic reuse purposes.