Tanvi Bhatia, S. S. Sindhu

Discover Agriculture • 2024

Recent climate variability, limited fertile land availability and soil degradation are major constraints to achieve food security for an ever-increasing human population. The adoption of intensive agriculture practices and highly productive agrosystems coupled with intensive use of agrochemicals has caused significant increases in agriculture production worldwide. This exhaustive production system has caused significant increases in generation and accumulation of large quantities organic wastes, which cause environmental pollution, deteriorate soil health and increase public health hazards. Conventional methods of organic waste management such as in situ burning of organic wastes, landfilling and chemical degradation are labour intensive, expensive and highly energy-consuming, and negatively impact the environment. Therefore, sustainable, eco-friendly and socially acceptable agri-technologies have been developed for value-added management of organic wastes and to obviate pollution problem. These biological technologies such as composting, anaerobic digestion, vermicomposting, production of biochar, organic phytostimulants, and bioremediation of pollutants have opened new vista for organic waste management. The addition of processed organic amendments (i.e., compost, vermicompost, biogas slurry and biochar) to the soil increases soil organic matter and nutrients availability, stimulates soil microbial community, contributes towards biocontrol of pathogens and also causes detoxification of pesticides. Furthermore, soil amendment with processed organic waste material, singly or with beneficial microbes, improved soil health, promoted growth of plants and increased the crop yields with less dependency on chemical fertilizers. In this article, the current technologies used for management of accumulated organic wastes are discussed for improving sustainable crop production, while maintaining environmental sustainability.

Nur Hidayati Othman, Nalan Kabay, Enver Güler

Reviews in Chemical Engineering • 2021

Abstract Reverse electrodialysis (RED) is among the evolving membrane-based processes available for energy harvesting by mixing water with different salinities. The chemical potential difference causes the movement of cations and anions in opposite directions that can then be transformed into the electrical current at the electrodes by redox reactions. Although several works have shown the possibilities of achieving high power densities through the RED system, the transformation to the industrial-scale stacks remains a challenge particularly in understanding the correlation between ion-exchange membranes (IEMs) and the operating conditions. This work provides an overview of the RED system including its development and modifications of IEM utilized in the RED system. The effects of modified membranes particularly on the psychochemical properties of the membranes and the effects of numerous operating variables are discussed. The prospects of combining the RED system with other technologies such as reverse osmosis, electrodialysis, membrane distillation, heat engine, microbial fuel cell), and flow battery have been summarized based on open-loop and closed-loop configurations. This review attempts to explain the development and prospect of RED technology for salinity gradient power production and further elucidate the integrated RED system as a promising way to harvest energy while reducing the impact of liquid waste disposal on the environment.

Min Xu

cIRcle (University of British Columbia) • 2010

A novel interconnected fluidized bed (IFB) reactor with a bypass line for chemical looping combustion (CLC) has been developed to overcome the problem of short residence time of oxygen carrier in the air reactor. A comprehensive hydrodynamic study was carried out on the cold-flow model of the proposed reactor. Detailed mapping of the operating conditions for the reactor system was studied. Pressure transducers were applied to investigate the pressure loops and the cross-sectional average solids hold-up along the air reactor. Solids circulation flux between the two reactors was measured using butterfly valves by estimating the time interval for collecting a given volume of solids. Helium was used as gas tracer for gas leakage measurement. The experiments examined the gas leakage from air reactor to fuel reactor, from fuel reactor to air reactor, from loop-seals to fuel reactor and from fuel reactor to the cyclone. For scaling consideration, the cold-flow reactor was operated with fluidizing gas mixture of helium and air to simulate the hydrodynamics of the hot unit. The effect of density ratio of solids to gas on the solids circulation flux, pressure loops and voidage distribution along the air reactor was investigated. The connection between cold unit and hot unit is achieved by applying a scaling law. It can be stated that the cold-flow model operated with fluidizing gas mixture of 96 vol% helium and 4 vol% air can be used to simulate the hydrodynamics of an atmospheric CLC hot unit. A comprehensive model for the investigation of the reactor is introduced by combining fluidization properties and a particle population balance for calculation of the bed particle conversion, considering the chemical reaction of a single particle. The dimensionless parameters, Mrfuel and Mrair, which represent the mass ratio of input oxidized-particles to the input fuel in unit time for the fuel reactor and the mass ratio of reduced-particles to the input oxygen in unit time for the air reactor, respectively, are introduced. The model shows that Mrfuel should be more than 50 for achieving fuel conversion of 90% in the fuel reactor and Mrair should be more than 60 for achieving oxygen conversion of 85% in the air reactor. A procedure for optimizing the performance of the atmospheric CLC reactor is developed. The modeling analysis indicated that the optimum operating condition of an atmospheric CLC reactor hot unit should be chosen as follows: fuel capacity is 80 kW, Ua0=6.6 m/s, Uf0= 0.076 m/s, UA1=4Umf, UA2=1Umf, and the temperature in air reactor is 1223 K and in fuel reactor is 1173 K.

Yaxin Huang, Ke Zhou, Huhu Cheng et al.

Advanced Functional Materials • 2023

Abstract Water‐enabled electricity generation technologies that are highly accessible and fundamentally clean are promising for next‐generation green energy. However, the challenge of scalability in both material processing and device fabrication greatly limits their practical applications. A high‐performance polyelectrolyte moist‐electric generator (MEG), which can be directly 3D printed for massive production and efficient integration, is reported. The printed MEG (p‐MEG) generates a high open‐circuit voltage of 0.8 V and a short‐circuit‐current density of 0.12 mA cm −2 by actively harvesting moisture from humid conditions. The synergistic effects of moisture gradient, ionic concentration gradient, and ion diffusion gradient, which remarkably enhance the driving force to separate ion pairs and notably facilitate the directional ion transport, are responsible for the high power generation performance of p‐MEG, as further backed up by in situ ion dynamics investigations and molecular simulations. When connected in serial and parallel, hundreds of p‐MEGs can deliver a high voltage of more than 180 V and a current of more than 1 mA. A constructed “moisture‐powered cup lamp” that lights up for hours further demonstrates the practicability of p‐MEG. This work provides a feasible and scalable 3D printing approach for the next‐generation environment‐adaptive self‐powered system.

Zichao Deng, Liang Xu, Huaifang Qin et al.

Advanced Materials • 2022

Water-current energy is an enormous and widely distributed clean energy in nature, with different scales from large ocean flow to small local turbulence. However, few effective technologies have been proposed to make use of different forms of water currents as a power source. Here, high-performance paired triboelectric nanogenerators (P-TENGs) capable of integrating massively into a thin flexible layer as a structured triboelectric surface (STS) are demonstrated for harvesting water-current energy. Novel gas packet exchange structure and rigid-flexible coupling deformation mechanism are introduced to ensure that the device can work very effectively even in deep water under high water pressure. The rationally designed TENG array in the STS enables highly efficient power take-off from the flow. Typically, the STS demonstrates a high-frequency output up to 57 Hz, largely superior to current TENG devices, and the power density is improved by over 100 times for triboelectric devices harvesting current energy. The flexible STS is capable of attaching to various surfaces or applying independently for self-powered sensing and underwater power supply, showing great potential for water-current energy utilization. Moreover, the work also initiates universal strategies to fabricate high-frequency devices under large environment pressure, which may profoundly enrich the design of TENGs.

Sara Arabi, Marie‐Laure Pellegrin, Jorge Aguinaldo et al.

Water Environment Research • 2020

This literature review provides a review for publications in 2018 and 2019 and includes information membrane processes findings for municipal and industrial applications. This review is a subsection of the annual Water Environment Federation literature review for Treatment Systems section. The following topics are covered in this literature review: industrial wastewater and membrane. Bioreactor (MBR) configuration, membrane fouling, design, reuse, nutrient removal, operation, anaerobic membrane systems, microconstituents removal, membrane technology advances, and modeling. Other sub-sections of the Treatment Systems section that might relate to this literature review include the following: Biological Fixed-Film Systems, Activated Sludge, and Other Aerobic Suspended Culture Processes, Anaerobic Processes, and Water Reclamation and Reuse. This publication might also have related information on membrane processes: Industrial Wastes, Hazardous Wastes, and Fate and Effects of Pollutants.

Yung‐Tse Hung, Hamidi Abdul Aziz, Siti Hafizan Hassan et al.

Water Environment Research • 2014

This review of literature published in 2013 focuses on waste related to chemical and allied products. The topics cover the waste management practices, hospital waste, perfume waste, pesticide waste, chemical wastewater, pesticide wastewater and pharmaceutical wastewater. The other topics include aerobic treatment, anaerobic treatment, sorption and ozonation.

Robert Pierrard, R. Mohan Sankaran

Plasma Processes and Polymers • 2025

ABSTRACT Non‐thermal, atmospheric‐pressure plasmas formed near liquids are typically in contact with metal at a boundary. Here, a new strategy is presented to generate a direct current (DC) plasma between a pair of liquid water surfaces. Characterization of the system shows that remarkably, plasma properties such as gas temperature and electron density remain constant over a wide current range. Concomitantly, this new reactor geometry was found to avoid a glow‐to‐arc transition at the highest currents studied. The reactor was applied to the degradation of phenol and found to achieve up to 90% removal in 60 min. The ability to sustain a high‐power DC plasma in direct contact with only liquid water is attractive for scalable applications in chemical synthesis and pollutant degradation.

Marwa Alaqarbeh, Syed Farooq Adil, Tamara Ghrear et al.

Catalysts • 2023

Palladium (Pd), a noble metal, has unique properties for C-C bond formation in reactions such as the Suzuki and Heck reactions. Besides Pd-based complexes, Pd NPs have also attracted significant attention for applications such as fuel cells, hydrogen storage, and sensors for gases such as H2 and non-enzymatic glucose, including catalysis. Additionally, Pd NPs are catalysts in environmental treatment to abstract organic and heavy-metal pollutants such as Cr (VI) by converting them to Cr(III). In terms of biological activity, Pd NPs were found to be active against Staphylococcus aureus and Escherichia coli, where 99.99% of bacteria were destroyed, while PVP-Pd NPs displayed anticancer activity against human breast cancer MCF7. Hence, in this review, we attempted to cover recent progress in the various applications of Pd NPs with emphasis on their application as sensors and catalysts for energy-related and other applications.

Ahmed H. El‐Sappah, Yumin Zhu, Qiulan Huang et al.

Frontiers in Plant Science • 2024

The contamination of soil and water with high levels of heavy metals (HMs) has emerged as a significant obstacle to agricultural productivity and overall crop quality. Certain HMs, although serving as essential micronutrients, are required in smaller quantities for plant growth. However, when present in higher concentrations, they become very toxic. Several studies have shown that to balance out the harmful effects of HMs, complex systems are needed at the molecular, physiological, biochemical, cellular, tissue, and whole plant levels. This could lead to more crops being grown. Our review focused on HMs' resources, occurrences, and agricultural implications. This review will also look at how plants react to HMs and how they affect seed performance as well as the benefits that HMs provide for plants. Furthermore, the review examines HMs' transport genes in plants and their molecular, biochemical, and metabolic responses to HMs. We have also examined the obstacles and potential for HMs in plants and their management strategies.

Wing-Sze Ho, Wei-Han Lin, Francis Verpoort et al.

Journal of Environmental Management • 2023

Sonia Saini, Sanjana Tewari, Jaya Dwivedi et al.

Materials Advances • 2023

Biofilm-mediated wastewater remediation has been developed as one of the most promising, inexpensive, and environmentally friendly technology as it breaks down contaminants via biotransformation, bioaccumulation, biomineralization, and biosorption.

Wenning Wang, Yuanyuan Huang, Yun Pan et al.

Foods • 2025

Sodium alginate, a natural anionic polysaccharide, exhibits broad potential applications in food, biomedicine, and environmental engineering due to its favorable biocompatibility, degradability, and functional tunability. This review systematically summarizes its chemical structure, physicochemical characteristics, sources, and extraction methods. It also focused on modification strategies, including chemical approaches (e.g., esterification, oxidation, sulfation, graft copolymerization), physical methods (composite modification, irradiation cross-linking, ultrasound treatment), and biological (e.g., enzyme regulation), and elucidated their underlying mechanisms. In the context of food science, special emphasis is placed on food-compatible chemistries and mild modification routes (such as phenolic crosslinking, enzyme-assisted coupling, and other green reactions) that enable the development of edible films, coatings, and functional carriers, while distinguishing these from non-food-oriented chemical strategies. The review further highlights novel applications of modified sodium alginate in areas including food packaging, functional delivery systems, drug release, tissue engineering, and environmental remediation (heavy metal and dye removal). Overall, this work provides a comprehensive perspective linking modification pathways to food-relevant applications and clarifies how chemical tailoring of alginate contributes to the design of safe, sustainable, and high-performance bio-based materials.

Corinna Schloderer, Sonil Nanda, Janusz A. Kozinski

Energies • 2026

To compete with fossil fuels, biofuels produced from renewable waste biomass must be cost-effective, adaptable to existing heat and power infrastructure, and possess desirable fuel properties and performance metrics matching those of fossil fuels, while having a much lower carbon footprint. However, handling and processing biowastes in thermochemical biorefineries is challenging owing to their high moisture content, low bulk density, poor grindability, low calorific value, and heterogeneous physicochemical properties. Torrefaction has emerged as an effective thermochemical technology for upgrading biowastes into torrefied biomass, which exhibits improved, homogeneous physicochemical properties, including higher calorific value, higher bulk density, better grindability, and hydrophobicity. This review synthesizes the current state of research on torrefaction, with particular emphasis on process parameters, reactor designs, commercial-scale implementations, and an analysis of its strengths, weaknesses, opportunities, and threats. The comparative advantages and limitations of different torrefaction reactors are highlighted, emphasizing how each reactor’s characteristics determine its suitability for specific circumstances and operating conditions. This article also considers the technical and economic challenges associated with scaling up torrefaction. The discussion on specific case studies on techno-economic analysis of torrefaction outlines the key barriers and provides incentives for researchers to consider when upscaling the technology. The strengths, weaknesses, opportunities, and threat analysis offers strategic insights for policymakers and industry stakeholders into possible actions to support torrefaction and its upscaling.

Hichem Ould Hamrane, Jean-Frederic Charpentier, Oualid Araar et al.

COMPEL The International Journal for Computation and Mathematics in Electrical and Electronic Engineering • 2026

Purpose This paper aims to perform a rigorous analytical evaluation of fully coreless axial-flux permanent magnet (AFPM) machines, targeting high-efficiency propulsion systems in unmanned vehicles. It focuses on the influence of permanent magnet geometries, winding topologies and current excitation types on key performance metrics. Design/methodology/approach A fully analytical framework is developed to evaluate 36 AFPM configurations. Using Coulombian charge and Biot–Savart laws, the magnetic field is modeled precisely. Back-electromotive force (EMF) and torque are derived under both sinusoidal and trapezoidal currents. Comparative analysis is performed based on total harmonic distortion (THD), torque ripple, efficiency and mass power density. Finally, the effectiveness and accuracy of the proposed approach are validated through 3D finite element simulations. Findings Performance is highly sensitive to the interplay between magnet shape, winding design and current waveform. Trapezoidal and curved rectangular windings, especially when paired with cylindrical or trapezoidal magnets and trapezoidal current, offer the best trade offs delivering high EMF, minimal THD, torque ripple reductions over 70% and efficiencies up to 97.5%. In contrast, triangular sector windings consistently yield the weakest performance. Originality/value This work introduces a fast, fully analytical tool for modeling and performance-driven optimization of coreless AFPM machines. It enables accurate, scalable evaluation of complex geometries and excitations without relying on computationally expensive numerical methods. The approach supports rapid design iteration and paves the way for next-generation high-speed, high-efficiency electric propulsion systems.

Yu Li, Jing Zhao, Janneke Krooneman et al.

The Science of The Total Environment • 2020

Cow manure represents a surplus manure waste in agricultural food sectors, which requires proper disposal. Anaerobic digestion, in this regard, has raised global interest owing to its apparent environmental benefits, including simultaneous waste diminishment and renewable energy generation. However, dedicated intensifications are necessary to promote the degradation of recalcitrant lignocellulosic components of cow manure. Hence, this manuscript presents a review of how to exploit cow manure in anaerobic digestion through different incentives extensively at lab-scale and full-scale. These strategies comprise 1) co-digestion; 2) pretreatment; 3) introduction of additives (trace metals, carbon-based materials, low-cost composites, nanomaterials, and microbial cultures); 4) innovative systems (bio-electrochemical fields and laser irradiation). Results imply that co-digestion and pretreatment approaches gain the predominance on promoting the digestion performance of cow manure. Particularly, for the co-digestion scenario, the selection of lignin-poor co-substrate is highlighted to produce maximum synergy and pronounced removal of lignocellulosic compounds of cow manure. Mechanical, thermal, and biological (composting) pretreatments generate mild improvement at laboratory-scale and are proved applicable in full-scale facilities. It is noteworthy that the introduction of additives (Fe-based nanomaterials, carbon-based materials, and composites) is acquiring more attention and shows promising full-scale application potential. Finally, bio-electrochemical fields stand out in laboratory trials and may serve as future reactor modules in agricultural anaerobic digestion installations treating cow manure.

Priyanka, I. H. Wood, Amthal Al‐Gailani et al.

Sustainability • 2024

The lasting impact of ancestral energy production operations and global manufacturing has not only generated substantial CO2 emissions, but it has also led to the release of metal-based pollutants into Earth’s water bodies. As we continue to engineer, mine (coal and metals), and now bore into geothermal wells/fracking sites for alternative energy sources, we continue to contaminate drinking water supplies with heavy metals through infiltration and diffusion, limiting progress towards achieving Sustainable Development Goals 3 (Sustainable Development Goal 3: Good health and well-being), 6 (Sustainable Development Goal 6: Clean water and sanitation), 14 (Sustainable Development Goal 14: Life below water), and 15 (Sustainable Development Goal 15: Life on land). This review shows how the research community has designed and developed mesoporous biochars with customizable pore systems, as well as functionalized biochars, to extract various heavy metals from water sources. This article investigates how biochar materials (non-activated, activated, functionalized, or hybrid structures) can be adapted to suit their purpose, highlighting their recyclability/regeneration and performance when remediating metal-based pollution in place of conventional activated carbons. By utilizing the wider circular economy, “waste-derived” carbonaceous materials will play a pivotal role in water purification for both the developed/developing world, where mining and heavy manufacturing generate the most substantial contribution to water pollution. This review encompasses a wide range of global activities that generate increased heavy metal contamination to water supplies, as well as elucidates emerging technologies that can augment environmental remediation activities, improving the quality of life and standard of living for all.

Val S. Frenkel, Gregg Cummings, Kris Y. Maillacheruvu et al.

Water Environment Research • 2020

Abstract Literature published in 2018 and literature published in 2019 related to food‐processing wastes treatment for industrial applications are reviewed. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following food‐processing industries and applications: general, meat and poultry, fruits and vegetables, dairy and beverage, and miscellaneous treatment of food wastes. Practitioner points This article summarizes literature reviews published in 2018 and in 2019 related to food processing wastes treatment for industrial applications are reviewed. This review is a subsection of the Treatment Systems section of the annual Water Environment Federation literature review and covers the following food processing industries and applications: general, meat and poultry, fruits and vegetables, dairy and beverage, and miscellaneous treatment of food wastes.

Yue Wang, Mathiyazhagan Narayanan, Xiaojun Shi et al.

Frontiers in Microbiology • 2022

Heavy metal contamination in soils endangers humans and the biosphere by reducing agricultural yield and negatively impacting ecosystem health. In recent decades, this issue has been addressed and partially remedied through the use of “green technology,” which employs metal-tolerant plants to clean up polluted soils. Furthermore, the global climate change enhances the negative effects of climatic stressors (particularly drought, salinity, and extreme temperatures), thus reducing the growth and metal accumulation capacity of remediating plants. Plant growth-promoting bacteria (PGPB) have been widely introduced into plants to improve agricultural productivity or the efficiency of phytoremediation of metal-contaminated soils via various mechanisms, including nitrogen fixation, phosphate solubilization, phytohormone production, and biological control. The use of metal-tolerant plants, as well as PGPB inoculants, should hasten the process of moving this technology from the laboratory to the field. Hence, it is critical to understand how PGPB ameliorate environmental stress and metal toxicity while also inducing plant tolerance, as well as the mechanisms involved in such actions. This review attempts to compile the scientific evidence on this topic, with a special emphasis on the mechanism of PGPB involved in the metal bioremediation process [plant growth promotion and metal detoxification/(im)mobilization/bioaccumulation/transformation/translocation] and deciphering combined stress (metal and climatic stresses) tolerance.

Wenchao Zhang, Hong Zhang, Ruyue Xu et al.

Frontiers in Microbiology • 2023

With the development of economy, heavy metal (HM) contamination has become an issue of global concern, seriously threating animal and human health. Looking for appropriate methods that decrease their bioavailability in the environment is crucial. Microbially induced carbonate precipitation (MICP) has been proposed as a promising bioremediation method to immobilize contaminating metals in a sustainable, eco-friendly, and energy saving manner. However, its performance is always affected by many factors in practical application, both intrinsic and external. This paper mainly introduced ureolytic bacteria-induced carbonate precipitation and its implements in HM bioremediation. The mechanism of HM immobilization and in-situ application strategies (that is, biostimulation and bioaugmentation) of MICP are briefly discussed. The bacterial strains, culture media, as well as HMs characteristics, pH and temperature, etc. are all critical factors that control the success of MICP in HM bioremediation. The survivability and tolerance of ureolytic bacteria under harsh conditions, especially in HM contaminated areas, have been a bottleneck for an effective application of MICP in bioremediation. The effective strategies for enhancing tolerance of bacteria to HMs and improving the MICP performance were categorized to provide an in-depth overview of various biotechnological approaches. Finally, the technical barriers and future outlook are discussed. This review may provide insights into controlling MICP treatment technique for further field applications, in order to enable better control and performance in the complex and ever-changing environmental systems.

Yating Cao, Haokun Li, Wei Zhang et al.

Applied Physics Letters • 2025

Ferroelectric tunnel junction (FTJ) based on hafnia/zirconia-based thin films has emerged as a promising class of nonvolatile memory, owing to their fast switching speeds, low power consumption, and full compatibility with complementary metal-oxide-semiconductor technology. Here, we report the fabrication of a high-performance FTJ based on 3.5 nm-thick Zr0.75Hf0.25O2 (ZHO) ferroelectrics with a remanent polarization of 12 μC/cm2. The fabricated TiN/WOx/ZHO/Pt FTJs exhibited large ON/OFF ratios (>1000) and good endurance of over 106 cycles, attributable to the robust ferroelectric properties and stability of electrodes. Micrometer-sized FTJ devices in crossbar structure delivered ultra-high read current densities of up to 520 A/cm2, and, importantly, the current density increases with shrinking FTJ, being attributed to a higher edge/corner effect from smaller electrodes. In addition, crossbar FTJ showed reliable synaptic phenomena including long-term potentiation/depression, paired-pulse facilitation/depression, and spike timing-dependent plasticity. This work demonstrates the excellent scalability of zirconia-based ferroelectric memory and their capability to emulate biological synapses.

Evgenia A. Goncharuk, Н. В. Загоскина

Molecules • 2023

The current state of heavy metal (HM) environmental pollution problems was considered in the review: the effects of HMs on the vital activity of plants and the functioning of their antioxidant system, including phenolic antioxidants. The latter performs an important function in the distribution and binding of metals, as well as HM detoxification in the plant organism. Much attention was focused on cadmium (Cd) ions as one of the most toxic elements for plants. The data on the accumulation of HMs, including Cd in the soil, the entry into plants, and the effect on their various physiological and biochemical processes (photosynthesis, respiration, transpiration, and water regime) were analyzed. Some aspects of HMs, including Cd, inactivation in plant tissues, and cell compartments, are considered, as well as the functioning of various metabolic pathways at the stage of the stress reaction of plant cells under the action of pollutants. The data on the effect of HMs on the antioxidant system of plants, the accumulation of low molecular weight phenolic bioantioxidants, and their role as ligand inactivators were summarized. The issues of polyphenol biosynthesis regulation under cadmium stress were considered. Understanding the physiological and biochemical role of low molecular antioxidants of phenolic nature under metal-induced stress is important in assessing the effect/aftereffect of Cd on various plant objects-the producers of these secondary metabolites are widely used for the health saving of the world's population. This review reflects the latest achievements in the field of studying the influence of HMs, including Cd, on various physiological and biochemical processes of the plant organism and enriches our knowledge about the multifunctional role of polyphenols, as one of the most common secondary metabolites, in the formation of plant resistance and adaptation.

Milena Marycz, Izabela Turowska, Szymon Glazik et al.

Sensors • 2025

Anaerobic digestion (AD) is increasingly recognized as a key technology for renewable energy generation and sustainable waste management within the circular economy. However, its performance is highly sensitive to feedstock variability and environmental fluctuations, making stable operation and high methane yields difficult to sustain. Conventional monitoring and control systems, based on limited sensors and mechanistic models, often fail to anticipate disturbances or optimize process performance. This review discusses recent progress in electrochemical, optical, spectroscopic, microbial, and hybrid sensors, highlighting their advantages and limitations in artificial intelligence (AI)-assisted monitoring. The role of soft sensors, data preprocessing, feature engineering, and explainable AI is emphasized to enable predictive and adaptive process control. Various machine learning (ML) techniques, including neural networks, support vector machines, ensemble methods, and hybrid gray-box models, are evaluated for yield forecasting, anomaly detection, and operational optimization. Persistent challenges include sensor fouling, calibration drift, and the lack of standardized open datasets. Emerging strategies such as digital twins, data augmentation, and automated optimization frameworks are proposed to address these issues. Future progress will rely on more robust sensors, shared datasets, and interpretable AI tools to achieve predictive, transparent, and efficient biogas production supporting the energy transition.

Xiaoyong Li, Zhi Wang, Yun He et al.

Methane • 2024

Low and unstable digestion performance is a challenging issue for anaerobic digestion, which prompts researchers to develop new strategies. In addition to traditional approaches such as co-digestion, pre-treatment, and recirculation, some emerging strategies, namely additive processes and microaeration, have also been recognized and developed in recent years. Many studies have evaluated the effect of these strategies on digestion performance. However, their comprehensive analysis is lacking, especially regarding the mechanisms of the different strategies. This review presents a comprehensive overview of research progress on these strategies based on the latest research, considering the five main strategies listed above. Through critical thinking, a summary of their mechanism, reactor performance, and availability of these strategies is presented. The results demonstrate that the contribution of microaeration is mainly to balance the composition and activity of hydrolysis, acidogenesis, and methanogenic archaea. Recirculation and co-digestion mainly balance mass and reaction environments. Pre-treatment, such as removing lignin, reducing cellulose crystallinity, and increasing the substrate-specific surface area, makes the characteristics of the substrate more conducive to the digestion of microorganisms. The mechanism of additive strategies varies greatly depending on the type of additive, such as enhancing interspecies electron transfer through conductive materials, resisting adverse digestion conditions through functional microbial additives, and accelerating nutrient absorption by regulating the bioavailability of trace elements. Although these strategies have different mechanisms for promoting digestion performance, their ultimate effect is to allow the parameters of the reactor to reach an ideal status and then achieve a balance among the substance, microorganisms, and water in an anaerobic reactor.

Godwin A. Udourioh, Moses M. Solomon, Jude A. Okolie

Food Science of Animal Resources • 2025

The dairy industry is a significant player in the food industry, providing essential products such as milk, cheese, butter, yogurt, and milk powder to meet the global population's needs. However, the industry's activities have resulted in significant pollution, with heavy waste generation, disposal, and effluent emissions into the environment. Properly handling dairy waste residues is a major challenge, with up to 60% of the total treatment cost in the processing unit allocated to waste management. Therefore, valorizing dairy waste into useful products presents a significant advantage for the dairy industry. Numerous studies have proposed various approaches to convert dairy waste into useful products, including thermochemical, biological, and integrated conversion pathways. This review presents an overview of these approaches and identifies the best possible method for valorizing dairy waste and by-products. The research presents up-to-date information on the recovery of value-added products from dairy waste, such as biogas, biofertilizers, biopolymers, and biosurfactants, with a focus on integrating technology for environmental sustainability. Furthermore, the obstacles and prospects in dairy waste valorization have been presented. This review is a valuable resource for developing and deploying dairy waste valorization technologies, and it also presents research opportunities in this field.

Ana García Romañach, F. Mattera, Henrik Lund Frandsen et al.

ECS Meeting Abstracts • 2025

Solid Oxide Electrolyser Cells (SOECs) have emerged as a leading technology in the Power-to-X (PtX) transition for converting surplus renewable electricity into e-fuels. Among SOEC processes, co-electrolysis of H₂O and CO₂ in SOEC has attracted significant interest due to its ability to produce syngas, which is a key feedstock for methanol and Fischer-Tropsch synthesis. Unlike separate electrolysis processes, co-electrolysis improves efficiency for methanol production by reducing the number of reactors required and minimizing the energy-intensive gas-shifting steps traditionally needed to achieve the desired H₂/CO ratio in syngas [1]. However, despite its potential, co-electrolysis faces operational challenges, particularly regarding carbon deposition on the fuel electrode at high feedstock utilisations, and long-term degradation that limits system performance [2]. To address these challenges, CO₂ electrolysis has been extensively investigated in previous work [3] as a foundation for understanding carbon-related degradation mechanisms in SOECs before advancing the research of this work to co-electrolysis. During CO 2 electrolysis carbon deposition occurs due to the Boudouard reaction (2CO ⇔ CO₂ + C), which is catalysed by nickel, with a theoretical temperature- and gas-composition-dependent threshold that determines a safe operation range to avoid carbon deposition. Nonetheless, carbon formation can take place below the expected equilibrium due to additional, often interlinked factors such as gas diffusion, electrode overpotentials, and impurities present in the CO₂ feed. These conditions intensify localized carbon deposition, especially at elevated current densities where concentration gradients between the gas channel and the fuel electrode-electrolyte interface become significant. While maintaining a stable voltage is often used as an indicator of operational stability in the presence of carbon-containing gases, recent findings [3] indicate that voltage stability alone is insufficient to rule out carbon deposition. Instead, early detection requires more advanced electrochemical diagnostics. In these recent findings, Electrochemical Impedance Spectroscopy (EIS) was identified as a powerful tool for monitoring carbon deposition during CO₂ electrolysis on SOEC, with characteristic shifts in impedance parameters serving as early warning signs. The ability to detect these changes before irreversible electrode damage occurs, presents an opportunity to develop diagnostic methods that can enable real-time operational adjustments. To further analyse the relationship between electrochemical behaviour and carbon deposition, two Python models were developed: an electrochemical model for estimating Boudouard equilibrium concentrations and cell voltage, and a Laplace-transform-based model to assess the effects of carbon deposition on impedance using an R s C deg (RC) equivalent circuit during step increases in current. The electrochemical model provided valuable insights, though deviations of up to 30% between model and experimental results were observed due to mounting inconsistencies, resistance variations, and cell degradation, underscoring the need for model refinement. Meanwhile, the Laplace transform model’s accuracy was limited by data acquisition challenges. This research also explored whether AC:DC operation, an innovative method of operation patented by Dynelectro that alternates between electrolysis and fuel cell mode [4], can reduce the risk of carbon deposition in SOEC cells. Experimental work at Dynelectro on CO₂ electrolysis on Ni-YSZ ∣ YSZ ∣ LSCF-GDC Solydera cells, involved current step increase tests and long-term operation under both DC and AC:DC conditions. The step increase tests, conducted with 0.8 A increments every 2–5 minutes, tracked impedance changes associated with carbon deposition. Long-term tests (20–50 min) were performed under average currents of 4–4.8 A and AC:DC frequencies of 0.01, 0.1, 1, and 30 Hz. CO concentrations were monitored using Quadrupole Mass Spectrometry (QMS), while EIS provided insights into cell behaviour through equivalent circuit fitting. Results confirmed that carbon deposition can be detected before causing irreversible cell damage by monitoring shifts in EIS parameters, particularly the decrease in summit frequency of the RC element below 0.05 Hz. This work demonstrated that carbon formation during CO₂ electrolysis can occur at outlet compositions with 10-20% less CO than the expected equilibrium concentration of 77.8% CO at 750 °C on Ni-containing SOEC, therefore emphasizing the need to define safe operational boundaries for CO₂ electrolysis in SOECs. Although the impact of AC:DC conditions on carbon deposition remained inconclusive at the single-cell level, findings suggested that it may have a significant effect in stack-level applications, where temperature gradients are more pronounced. Despite these findings in CO₂ electrolysis, their applicability to co-electrolysis remains uncertain due to the added complexity introduced by simultaneous H₂O reduction, reverse water-gas shift (RWGS) and methanation reactions. A critical gap in current research lies in the predictive modelling of carbon deposition during co-electrolysis under realistic operating conditions. While theoretical carbon deposition thresholds can be calculated based on inlet gas partial pressures and temperature, additional local factors such as gas concentration gradients along the cell, impurity-driven overpotentials, and variations in reaction kinetics must be considered to refine predictions. This research aims to address this gap by investigating how these phenomena influence carbon deposition and by extending previous findings into the context of co-electrolysis with two key objectives: Can carbon formation during co-electrolysis in SOECs be predicted and, if so, prevented to ensure a safe operation window? A detailed mathematical model is being developed to quantify carbon deposition under varying CO₂/H₂O ratios and operating conditions. By incorporating reaction kinetics, mass transport effects, and electrochemical behaviour, this model seeks to provide a predictive framework for identifying conditions that minimize carbon risk while maximizing syngas yield. The model is being designed to integrate with Dynelectro’s existing SOEC simulation framework. Experimental validation is a key component of this study, involving SOEC tests under controlled co-electrolysis conditions. Carbon deposition will be assessed using a combination of gas analysis techniques, post-mortem electrode characterization, and real-time impedance spectroscopy. Special attention will be given to correlating EIS-derived parameters with observed carbon buildup, with the goal of refining diagnostic capabilities. The objective is to develop a tool that can detect early-stage carbon deposition based on impedance shifts, enabling operational adjustments to prevent long-term degradation. Can AC:DC operation reduce the risk of carbon deposition during co-electrolysis, enabling higher CO concentrations and more efficient syngas production? AC:DC operation has previously been shown to enhance SOEC durability by reducing localized thermal gradients and minimizing degradation mechanisms associated with steady-state DC operation [4], [5]. In co-electrolysis, where carbon formation is highly sensitive to temperature fluctuations and gas-phase composition, AC:DC operation may provide additional benefits by stabilizing reaction environments. One potential advantage of AC:DC operation is its ability to expand the safe operating range for co-electrolysis. By maintaining higher outlet temperatures, particularly in the driest conditions where steam concentration is lowest, the Boudouard equilibrium can be shifted toward higher CO concentrations, thereby increasing the safety margin for carbon deposition, as shown in Figure 1. Additionally, higher temperatures reduce the Area Specific Resistance (ASR), lowering overall cell overvoltages and possibly further mitigating carbon risk. Beyond thermal stabilization, AC:DC operation may also influence the behaviour of carbon-forming impurities. Certain gas-phase contaminants, such as sulphur species, have been shown to accelerate carbon deposition by increasing electrode overpotential [6], [7]. AC:DC cycling has the potential to either remove or transform these impurities into less reactive forms, delaying the onset of carbon buildup. However, this hypothesis has not been thoroughly tested in co-electrolysis conditions, making it a key focus of ongoing research. If validated, AC:DC operation could provide a practical method for avoiding carbon deposition, improving syngas quality and reducing cell degradation, thereby ensuring long-term stability and effici

Laura Murphy, David O’Connell

Fermentation • 2024

The implementation of the circular bioeconomy is now widely accepted as a critical step towards reducing the environmental burden of industrial waste and reducing the impact of this waste on climate change. The valorisation of waste using microorganisms is an attractive and fast-developing strategy capable of achieving meaningful improvements in the sustainability of the biotechnology industry. Yeasts are a powerful chassis for developing valorisation strategies and key opportunities. Thus, this study examines how waste from the food sector can be effectively targeted for valorisation by yeast. Yeasts themselves are critically important elements in the production of food and brewing, and thus, the valorisation of waste from these processes is further reviewed. Policy and regulatory challenges that may impact the feasibility of industrial applications of yeast systems in the valorisation of food waste streams are also discussed.

Xiaoqiang Zhang, Chaomurilige, Xingchao Han et al.

• 2025

Metal oxides, particularly the $\mathrm{Co}_{3} \mathrm{O}_{4} / \mathrm{CoO}$ system, have emerged as promising thermochemical energy storage materials due to their superior properties, including high operating temperatures, high energy density, ambient storage without time limitations, and suitability for long-distance transportation. These attributes make them ideal for large-scale applications such as renewable energy storage, power generation, and even household energy systems. However, their technical readiness level (TRL) is currently limited to 1–4, lagging behind sensible and latent thermal energy storage technologies, which are already commercialized with TRLs of 6–9. The primary challenge lies in achieving a balance between thermochemical performance and mechanical integrity during scale-up. This entails enhancing mechanical stability while maintaining an appropriate reaction temperature, reaction rate, and energy storage density. In this study, the $\mathrm{Co}_{3} \mathrm{O}_{4} / \mathrm{CoO}$ metal oxide pair for thermochemical energy storage is systematically investigated. Pure $\mathrm{Co}_{3} \mathrm{O}_{4} / \mathrm{CoO}$ is optimized by doping with varying amounts of Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> (5 wt% to 20 wt%). The microstructure and morphologies of the materials are analyzed, alongside their thermochemical properties and mechanical strength. The results indicate that $\mathrm{Co}_{3} \mathrm{O}_{4} / \mathrm{CoO}$ with 10 wt% Al<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf>O<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> achieves a favorable balance, exhibiting a significant enthalpy change, improved mechanical stability, high porosity, and a well-preserved specific surface area. Furthermore, cycling experiments confirm the advantages of the developed materials, demonstrating their potential for enhanced performance and durability in thermochemical energy storage applications.

Ojima Wada, Abimbola O. Ige, Bamise I. Egbewole et al.

Sustainable Chemistry One World • 2026

Wastewater management has undergone significant evolution from medieval practices, where wastewater was directly discharged into surface water bodies, to modern approaches that emphasise not only treatment for public health but also the recovery of valuable resources. This evolution reflects a shift from unidimensional wastewater treatment focused solely on health protection to a multipurpose framework that includes water reclamation, reuse, and resource recovery. This narrative review assesses recent developments in wastewater resource recovery technologies and highlights global disparities in their adoption. By analysing research outputs using relevant keywords such as "Circular Economy," "Wastewater," and "Resource Recovery," the review reveals a significant concentration of research and technological development in the Global North, particularly in Europe and East Asia (mainly China). In contrast, regions like Sub-Saharan Africa (excluding Southern Africa) and parts of Southeast Asia remain largely underserved, hindered by limited infrastructure, inadequate funding, and insufficient institutional support. Key resources recovered include nutrients and soil amendments, feed and bioproducts, bioenergy, and metals. Out of 61 studies synthesised and comparatively analysed, 39% originated from Europe, while none emanated from West and Central Africa, illustrating a stark imbalance in research and innovation. The implications of these disparities are far-reaching. Recommendations for advancing wastewater resource recovery globally were offered, emphasising the importance of inclusive and equitable progress to ensure that no region is left behind in this critical aspect of sustainable development.

Mona A. Abdel‐Fatah

Sustainability • 2023

In 2019, a staggering 931 million tons of food went to waste, which is equal to about 17% of all the food available in stores. Dealing with this waste and managing wastewater from various industries will be among the world’s top challenges soon. This is because the global population is expected to grow to around 9 billion people by 2050. Food processing effluent is characterized by valuable material in considerable concentrations, including proteins and lipids with low concentrations of heavy metals and toxicants. Developing an integrated management system for food-processing wastewater should focus on recovering abundant resources, improving the economic value of the process, and mitigating the organic contaminant in the food-processing effluent. This state-of-the-art will review the wastewater management processes of the food processing industry. The latest wastewater treatment processes in different food processing sectors will be reviewed. This review will encompass various physicochemical treatment and recovery techniques, such as precipitation, membrane technology, solvent extraction, foam fractionation, adsorption, and aqueous two-phase systems. Additionally, it will delve into bio-treatment processes that leverage microorganisms and/or enzymes to utilize nutrients found in food-processing wastewater as cost-effective substrates for the production of valuable products. This includes a detailed examination of microalga biomass production within wastewater treatment systems. Finally, the review will put forward future research directions aimed at integrating the principles of the circular economy and developing comprehensive food-processing wastewater management systems.

ChenHongWen Zeng, Yew Heng Teoh, Heoy Geok How et al.

Journal of Electrochemical Science and Engineering • 2026

Ultrasound intensifies hydrogen production in water electrolysis cells by thinning boun­dary layers, accelerating bubble detachment, and, in tuned windows, modulating cavi­tation chemistry, yet cross-study claims remain difficult to compare. Focusing on ultra­sound-enhanced water electrolysis (sono-electrolysis), this review aligns reporting with IEC 61161 (radiation-force acoustic power) and IEC 62127-2:2025 (hydrophone calibra­tion); requires delivered acoustic intensity at the electrode, Idel / W·cm⁻², with stated trace­ability; pairs isothermal control with uncertainty budgets; and benchmarks perfor­mance using Δ-metrics: Δj (current-density gain at fixed cell voltage), Δη (cell voltage/over­po­tential reduction at fixed current density) and ΔH₂ (hydrogen production rate gain at matched electrical input), together with specific energy consumption (SEC, kWh·kg⁻¹ H₂). A window-based synthesis indicates that, under isothermal operation, 20 to 40 kHz with delivered intensity ≈0.2 to 1.0 W·cm⁻² reproducibly yields Δj ≈ 15 to 30 %, Δη ≈ 40 to 120 mV, ΔH₂ ≈ 10 to 30 %, and net SEC improvements of ~8 to 12 % when auxiliary loads are included, whereas at higher dose (Idel ≈ 1.0 to 1.6 W·cm⁻²) non-uniform fields, cloud shielding, and heating can saturate or reverse benefits. To prevent metric conflation, hybrid sono-hydrogen routes are reviewed separately. The review concludes by proposing a minimum reporting set-frequency, waveform/duty and pulse repetition frequency, Idel (traceability/uncertainty), geometry/stand-off, electrolyte and dissolved gas, bulk tempe­rature and runtime, gas metrology with temperature/pressure cor­rections, SEC boun­daries and replicates/statistics, and by outlining priorities for operando cavitation-electro­chemistry co-registration, geometry/void-fraction-aware scale-up, and durability under combined fields, to support reproducible, energy-accounted, and comparable studies across laboratories.

Ahmed Tawfik, Mohamed Eraky, Ahmed I. Osman et al.

Environmental Chemistry Letters • 2023

Abstract Adopting waste-to-wealth strategies and circular economy models can help reduce biowaste and add value. For instance, poultry farming is an essential source of protein, and chicken manure can be converted into renewable energy through anaerobic digestion. However, there are a number of restrictions that prevent the utilization of chicken manure in bioenergy production. Here, we review the conversion of chicken manure into biomethane by anaerobic digestion with focus on limiting factors, strategies to enhance digestion, and valorization. Limiting factors include antibiotics, ammonia, fatty acids, trace elements, and organic compounds. Digestion can be enhanced by co-digestion with sludge, lignocellulosic materials, food waste, and green waste; by addition of additives such as chars, hydrochars, and conductive nanoparticles; and by improving the bacterial community. Chicken manure can be valorized by composting, pyrolysis, and gasification. We found that the growth of anaerobic organisms is inhibited by low carbon-to-nitrogen ratios. The total biogas yield decreased from 450.4 to 211.0 mL/g volatile solids in the presence of Staphylococcus aureus and chlortetracycline in chicken manure. A chlortetracycline concentration of 60 mg/kg or less is optimal for biomethanization, whereas higher concentrations can inhibit biomethane production. The biomethane productivity is reduced by 56% at oxytetracycline concentrations of 10 mg/L in the manure. Tylosin concentration exceeding 167 mg/L in the manure highly deteriorated the biomethane productivity due to an accumulation of acetate and propionate in the fermentation medium. Anaerobic co-digestion of 10% of primary sludge to 90% of chicken manure increased the biogas yield up to 8570 mL/g volatile solids. Moreover, chemicals such as biochar, hydrochar, and conducting materials can boost anaerobic digestion by promoting direct interspecies electron transfer. For instance, the biomethane yield from the anaerobic digestion of chicken manure was improved by a value of 38% by supplementation of biochar.

Aliyu Ishaq, Mohd Ismid Mohd Said, Shamila Azman et al.

Environmental Science and Pollution Research • 2023

Landfill leachate, which is a complicated organic sewage water, presents substantial dangers to human health and the environment if not properly handled. Electrochemical technology has arisen as a promising strategy for effectively mitigating contaminants in landfill leachate. In this comprehensive review, we explore various theoretical and practical aspects of methods for treating landfill leachate. This exploration includes examining their performance, mechanisms, applications, associated challenges, existing issues, and potential strategies for enhancement, particularly in terms of cost-effectiveness. In addition, this critique provides a comparative investigation between these treatment approaches and the utilization of diverse kinds of microbial fuel cells (MFCs) in terms of their effectiveness in treating landfill leachate and generating power. The examination of these technologies also extends to their use in diverse global contexts, providing insights into operational parameters and regional variations. This extensive assessment serves the primary goal of assisting researchers in understanding the optimal methods for treating landfill leachate and comparing them to different types of MFCs. It offers a valuable resource for the large-scale design and implementation of processes that ensure both the safe treatment of landfill leachate and the generation of electricity. The review not only provides an overview of the current state of landfill leachate treatment but also identifies key challenges and sets the stage for future research directions, ultimately contributing to more sustainable and effective solutions in the management of this critical environmental issue.

Gus Floerchinger, Omid Babaie Rizvandi, Robert J. Braun

ECS Meeting Abstracts • 2025

Introduction : Commercial-scalesolid oxide cell (SOC) systems offer a unique and attractive solution to the challenge of supplying high-efficiency and fuel-flexible power at competitive system costs using low-carbon fuels [1, 2]. These systems require repeating SOC stack assemblies to be packaged into multi-stack modules (MSMs) to bring system capacity to the MW scale. During the system design phase, relatively simple models (e.g., single-cell representations) of the SOFC power block are often used to develop system-level models for performing trade studies, developing system requirements, and/or estimating performance. Such simplified approaches typically assume that thousands of cells operate equivalently, and neglect consideration of the coupled thermal-fluidic, electrochemical, and power electronic aspects associated with multi-stack assemblies. These simplifications may be computationally efficient but can also lead to overestimation of system efficiency performance, under prediction of both higher thermal gradients that may be present within stacks and considerable inter-stack heat transfer, and larger variance than expected in other stack operating parameters, such as fuel utilization. While careful design of multi-stack modules can help to mitigate the negative impacts of scaling SOC systems, there are interacting effects to balance of plant (BOP) components that should be addressed to ensure that the system meets both performance targets, such as power density, efficiency, and operability within the stack operating envelope. This work draws on kW-scale testing of MSM assemblies and explores how impactful deviations in stack-to-stack operation can result in reduced system performance, especially in cases where significant gas maldistribution is present between stacks within MSMs or between multiple MSM arrays. The presentation provides an overview of computational modeling and experimental testing to assess how single-cell representations versus more detailed (3-D stack and MSM) models for the SOFC power block impact stack and system performance estimation. In particular, the effect of gas maldistribution on system efficiency, SOFC operational limits, and BOP sizing is quantified through experimentally validated model-based simulation. Methodology: The system concept modeled in this work is an 80 kW rated hybrid SOFC-internal combustion engine system [3, 4]. The engine is used as a bottoming cycle to increase system efficiency by utilizing the remaining reactant gases in the SOFC exhaust stream to generate power. Fresh reactant gases are conditioned and compressed to the system operating pressure of 3 bar absolute. The fuel stream is blended with anode exhaust recycle gas and preheated and partially reformed in a packed bed reactor before entering the SOFC modules which are made up of twelve 5 kW stack assemblies packages into 3 MSMs. Positive displacement compressor hardware brings fresh air up to the operating pressure and is preheated to supply the SOFC modules. Preheating is done through gas-to-gas recuperative heat exchangers that utilize the hot exhaust gas streams to preheat the inlet gas streams. Unreacted exhaust gas that is not recycled is sent to a spark-ignited internal combustion engine (SI-ICE) to produce additional power to increase system efficiency and overcome parasitic loads in the system. A flow diagram of the system is shown below. Two SOFC modeling approaches are compared for the system concept described above. The first uses a simplified approach that only models a single repeating unit (RU) for the SOFC modules. This approach assumed that all cells would act identically to one another and that no effects arise due to stack and module construction. The SOC cells are modeled using a one-dimensional “down the channel” framework to capture the temperature, species composition, and current distributions over the active area of the cells. The simplified single-cell representation of the SOC body simply multiplies the expected outputs of the cell by the cell count. By contrast, the second framework uses an MSM model in which each SOFC stack is modeled independently with individually tunable parameters for their thermal, flow, and electrochemical operation. These models are tuned to manufacturer data for specific stacks as well as experimental characterization of 1 and 5 kW stacks done at Colorado School of Mines. Each stack is manifolded such that gases are delivered to each stack via the common port. Within a module, the flow of reactant gases to each stack is not equal and is quantified by its maldistribution; represented as a percentage difference from the ideal fraction of flow delivered to each stack as seen in equation 1 for stack in position i as follows: The module external manifolds are modeled as a discrete pipe network and are benchmarked against a high-fidelity CFD model of the manifolds in COMSOL Multiphysics and experimental characterization of manifolds and module operation [5-7] . The experimental test bed used to inform the multi-stack and system levels models is a grid connected, 36kW capacity, pressurized rig capable of testing both multi-stack modules and single-stack test modules (STMs) within a pressure vessel equipped with numerous feedthroughs for routing of gas plumbing, diagnostics, and electric power lines. This vessel maintains stack operating pressures up to 10 bar a . The test bed is capable of running on reformed natural gas as well as simulated gas mixtures. The MSM is outfitted with thermocouples and pressure taps at the inlet and exhaust ports of each stack for diagnostic measurements. In-line heaters placed within the vessel bring the gases to operating temperature [5-8]. The data collected from experimental characterization of MSMs helps to inform modeling efforts. First, pressure drop characteristics for each stack within a module are quantified to accurately predict the gas maldistribution to each stack for a given flow condition. Secondly, a set of cell material tuning parameters found to fit model polarization curves to the experimental data. Finally, effective insulation parameters for each stack are quantified using temperature data of the outer module case taken at multiple points under load. Results: The hybrid system configuration defined above is simulated using both the single-cell and MSM representations for the SOFC assembly in three cases. Case A uses the single-cell representation where all cells are assumed to operate equally within the SOFC assembly. Cases B and C model the full MSM assemblies with a maximum gas maldistribution in the stack external manifolds of 10% and 20%, respectively. This gas maldistribution is imposed such that the first stack on the manifold rail received the maximum flow (10% or 20%, respectively) and reduced linearly to the fourth stack which received the least flow (-10% or -20% respectively). Table 1 shows the system operating conditions, efficiency, and net system power for the cases tested. The average fuel utilization for all stacks is held constant at 65% and the cathode outlet temperature among all stacks is constrained to maximum of 630°C. The average stack current for all cases was 32 amps. Comparing Case A in which a single cell model was used to cases B and C which use MSM models shows that the introduction of MSMs decreases the system efficiency by up to 9% in the case of ±20% gas maldistribution. Because the maximum cathode outlet temperature is constrained at 630°C to ensure safe operation, cases B and C must flow more air through the cathode to account for the stack which received the lowest airflow due to maldistribution even though the module outlet temperature falls well below the 630°C limit. Therefore, the parasitic load of the air compressor hardware increases significantly. This increase in load results in a drop of efficiency of up to 9% for case C. Additionally. The system power is de-rated to take up the additional parasitic load by up to 10 kW. Conclusions : This study explores the limitations of simplified modeling approaches for commercial-scale solid oxide cell (SOC) systems. Conventional single-cell representations fail to capture critical thermal-fluidic, electrochemical, and power electronic interactions within multi-stack modules (MSMs). In the effects studied. Including experimentally validated MSM models captures phenomena that may require de-rating system power by up to 10%, to mitigate potential losses not shown with simplified models. These results highlight the necessity of more comprehensive modeling approaches during system design to accurately predict performance parameters and ensure MW-scale SOC systems can meet both efficiency targets and operational stability requirements while maintaining competitive costs in the low-carbon energy landscape. References: [1] D. E. Tew, R. A. Cox-Galhotra, V. R. Lecoustre, M. Lyubovsky, and G. L. Soloveic

Marta Fernández-Gatell, Xavier Sánchez‐Vila, Jaume Puigagut

The Science of The Total Environment • 2022

T. P. Francis, Jarosław Syzdek, Tryston Schmitt et al.

ECS Meeting Abstracts • 2025

Water electrolysis is an essential electrochemical process for both oxygen production in space as well as green hydrogen production on Earth. The presence of bubbles on electrodes increases the resistivity of the electrolytic cell and hinders mass-transport of the liquid electrolyte to the electrode surface. On Earth, efficiency losses due to the presence of bubbles can be as high as 30%, and potentiostatic parabolic plane experiments have shown a further decrease by 11% at current densities up to 100 mA/cm 2 . Among a variety of methods for accelerating bubble evacuation from the electrode surface, magnetohydrodynamic (MHD) pumping via a magnetically-induced Lorentz force has shown promise in controlled lab trials. The MHD effect reduced bubble coverage by 50% under a 1 T field and increased hydrogen-evolution current density by 25% at 700 mA/cm 2 under a 5 T field. Experiments employing permanent magnets have shown a 5% decrease in cell overpotential from B-fields of 0.2 T at 150 mA/cm 2 . In this work, we describe the modeling and testing of alkaline water electrolysis conducted in the presence of a magnetic field produced by a scalable Halbach array of permanent magnets. Unlike many prior efforts, the field is produced by off-the-shelf rare-Earth N52 magnets of various sizes. These arrays are located just behind the electrodes in a “Halbach” sinusoidal pattern which serves to amplify the magnetic field strength. Bench-top tests of a pair of 1.6 cm 2 electrodes show an 18.4% efficiency increase at current densities between 25-300 mA/cm 2 . Since the magnets are permanent, there is no additional power required for generating the MHD swirling, aside from a trivial overpotential of ~0.05% of cell power. This architecture presents a promising solution for scalability for industrial electrolyzers. Figure 1

Muntasir Shahabuddin, Ravindra Datta, Xiaowei Teng et al.

Journal of The Electrochemical Society • 2026

Despite their promise as scalable platforms for heterogeneous electrochemistry, slurry electrodes struggle with high power operation either due to their low conductivity, or the inherent kinetic and transport limitations of the supported electrochemical reaction. In this paper, we reveal order of magnitude improvements to flow cell power densities by leveraging capacitive effects in short residence time slurry electrodes. This outcome is sensitive to the residence time of electrode material and applied current density in the half cell due to the concerted interplay of capacitive double layer and faradaic currents. Using a 1D porous electrode model tied to Fe 2+ /Fe 3+ half-cell experiments, we deconvolve this interplay and map operating regimes of power draw versus residence time and applied current density. We experimentally find that short residence times (∼1–10 s) drive primarily capacitive discharge, enabling power densities up to an order of magnitude higher than pseudo-steady state (&gt;1 min residence time), primarily faradaic, operation. Our findings suggest that distinguishing capacitive vs faradaic current contribution reframes performance improvements often ascribed to improved mass transfer instead as advection of double layer charge and shifts in charge transport timescales. These findings offer practitioners design criteria that can be applied directly in scaling high power density electrochemical cells and reactors employing slurry electrodes.

A.M. Hulme, Chris Davey, Sean Tyrrel et al.

Journal of Membrane Science • 2021

Whilst reverse electrodialysis (RED) has been extensively characterised for saline gradient energy from seawater/river water (0.5 M/0.02 M), less is known about RED stack design for high concentration salinity gradients (4 M/0.02 M), important to closed loop applications (e.g. thermal-to-electrical, energy storage). This study therefore focuses on the scale-up of RED stacks for high concentration salinity gradients. Higher velocities were required to attain a maximum Open Circuit Voltage (OCV) for 4 M/0.02 M, which gives a measure of the electrochemical potential of the cell. The experimental OCV was also much below the theoretical OCV, due to the greater boundary layer resistance observed, which is distinct from 0.5 M/0.02 M. However, negative net power density (net produced electrical power divided by total membrane area) was demonstrated with 0.5 M/0.02 M for larger stacks using shorter residence times (three stack sizes tested: 10 × 10cm, 10 × 20cm and 10 × 40cm). In contrast, the highest net power density was observed at the shortest residence time for the 4 M/0.02 M concentration gradient, as the increased ionic flux compensated for the pressure drop. Whilst comparable net power densities were determined for the 10 × 10cm and 10 × 40cm stacks using the 4 M/0.02 M concentration gradient, the osmotic and ionic transport mechanisms are distinct. Increasing cell pair number improved maximum current density. This subsequently increased power density, due to the reduction in boundary layer resistance, and may therefore be used to improve thermodynamic efficiency and power density from RED for high concentrations. Although comparable power densities may be achieved for small and large stacks, large stacks maybe preferred for high concentration salinity gradients due to the comparative benefit in thermodynamic efficiency in single pass. The greater current achieved by large stacks may also be complemented by an increase in cell pair number and current density optimisation to increase power density and reduce exergy losses.

Linda Brösgen, Robin Kunkel, Julia Melke

ECS Meeting Abstracts • 2024

Flow reactors are an attractive process for a variety of applications in the chemical industry. This is due to advantages over batch processes, such as good scalability and constant product quality with precisely controllable reaction conditions. [1] Regarding the industrial transition towards a climate-friendly and CO 2 -neutral economy, electrolysis and electrosynthesis processes are a focus of current research. These make it possible to use electricity from renewable energies directly and at the same time fulfil several criteria of green chemistry [2]. However, they currently often require the use of platinum group metals (PGM) and need separators that are mostly based on perfluorinated and polyfluorinated alkyl substances (PFAS) [3]. In addition, conventional electrolysis processes used to produce green hydrogen require high overvoltage. These can be traced back to the oxygen evolution reaction (OER). Furthermore, oxygen is not a value-added product. For these reasons, there is increasing interest in coupled systems in which the sluggish OER is replaced by a thermodynamically more efficient reaction that also generates a value-added product. One possibility for this is the electrooxidation of biobased 5-HMF to the platform chemical 2,5-furandicarboxylic acid (FDCA) [4]. A theoretical cell voltage of 0.3 V is required for the FDCAER/HER, whereas the OER/HER requires 1.23 V [5]. [6] The simultaneous production of platform chemicals and green H 2 by paired electrolysis is a promising approach to enable sustainable and energy-efficient systems. Currently, this technology is still in the development stage and studies have so far focused on batch cell trials. [4,5,7] However, the use of flow reactors can further reduce overvoltage’s. This is due to factors such as better mass transport, an optimized reactor-volume/electrode ratio and minimized electrode gaps. In addition, more stable process conditions and a simplified scale-up point in favor of transferring to a flow system as early as possible [8,9]. [4–14] In previous experiments H-cell experiments for electrochemical 5-HMF conversion to FDCA were carried out on nickel base materials [14]. On this foundation, a modular flow-through test cell was developed on a laboratory scale and the feasibility of coupled electrolysis in the flow reactor in recirculating operation was investigated. Particular attention was paid to mild operating conditions (e.g. mild alkaline environment, low operating pressures and low temperatures). For this purpose, polarization curves followed by bulk electrolysis were recorded and the 5-HMF conversion was monitored analytically using UV-VIS. The measurements were carried out on Ni-foam. Subsequently, experiments were carried out to switch from recirculation mode to single-pass operation. For this purpose, Ni-foam and NiOOH foam electrodes were prepared electrochemically and investigated at different flow rates, current densities, and reactant concentrations in the flow cell. The bulk electrolysis was accompanied by analysis (HPLC, UV-VIS) to quantify and classify the derivatives of the electrosynthesis process. These experiments yielded important results about the system, which enabled operational adjustments and a scale-up. In general, this research is advancing the development of efficient and sustainable energy sources and the synthesis of platform molecules using renewable raw materials in a hydrogen co-electrolysis. Acknowledgments The authors thank the European Union's Horizon Europe research and innovation program under grant agreement N° 101070856 ELOBIO (Electrolysis of Biomass) for funding. References [1] Derek Pletcher, Electrochemistry Communications 88 (2018) 1–4. [2] B.A. Frontana-Uribe, R.D. Little, J.G. Ibanez, A. Palma, R. Vasquez-Medrano, Green Chem. 12 (2010) 2099–2119. [3] Perfluoralkylchemikalien (PFAS) - ECHA, 2023. Available from: https://echa.europa.eu/de/hot-topics/perfluoroalkyl-chemicals-pfas (02.15.2023). [4] B. Garlyyev, S. Xue, J. Fichtner, A.S. Bandarenka, C. Andronescu, ChemSusChem 13 (2020) 2513–2521. [5] Y. Yang, T. Mu, Green Chem. 23 (2021) 4228–4254. [6] Pongkarn Chakthranont, Sarinya Woraphutthaporn, Chotitath Sanpitakseree, Kasempong Srisawad, Kajornsak Faungnawakij, Chemical Engineering Journal 476 (2023) 146478. [7] G. Chen, X. Li, X. Feng, Angewandte Chemie (International ed. in English) 61 (2022) e202209014. [8] D. Pletcher, R.A. Green, R.C.D. Brown, Chemical reviews 118 (2018) 4573–4591. [9] F.C. Walsh, C. Ponce de León, Electrochimica Acta 280 (2018) 121–148. [10] UNFCCC. [11] The European Green Deal, 2020. [12] R. Latsuzbaia, R. Bisselink, A. Anastasopol, H. van der Meer, R. van Heck, M.S. Yagüe, M. Zijlstra, M. Roelands, M. Crockatt, E. Goetheer, E. Giling, J Appl Electrochem 48 (2018) 611–626. [13] D. Cantillo, Current Opinion in Electrochemistry 44 (2024) 101459. [14] L. Brösgen, C. Lam, J. Tübke, R. Kunkel, J. Melke, Meet. Abstr. MA2023-02 (2023) 1410.

Diego Maureira, Oscar Romero, Andrés Illanes et al.

Biotechnology Advances • 2023

Bioelectrochemistry has gained importance in recent years for some of its applications on waste valorization, such as wastewater treatment and carbon dioxide conversion, among others. The aim of this review is to provide an updated overview of the applications of bioelectrochemical systems (BESs) for waste valorization in the industry, identifying current limitations and future perspectives of this technology. BESs are classified according to biorefinery concepts into three different categories: (i) waste to power, (ii) waste to fuel and (iii) waste to chemicals. The main issues related to the scalability of bioelectrochemical systems are discussed, such as electrode construction, the addition of redox mediators and the design parameters of the cells. Among the existing BESs, microbial fuel cells (MFCs) and microbial electrolysis cells (MECs) stand out as the more advanced technologies in terms of implementation and R&D investment. However, there has been little transfer of such achievements to enzymatic electrochemical systems. It is necessary that enzymatic systems learn from the knowledge reached with MFC and MEC to accelerate their development to achieve competitiveness in the short term.