Linhua Fan

Highly porous and hydrophobic thermally rearranged polybenzoxazole-co-imide (TR PBOI) nanofiber membranes with tuneable morphologies were successfully fabricated via electrospinning followed by solid-state thermal rearrangement of ortho-acetyl copolyimide (AcPI) precursors for desalination by direct contact membrane distillation (DCMD). Controlled surface architectures, including microparticles and beads-on-string structures on TR nanofiber layers, played a key role in enhancing surface roughness and hydrophobicity. The resulting TR composite membranes exhibited high water contact angles (>140°) and excellent thermal stability. The performance evaluation in the DCMD system using 3.5 wt% NaCl solution showed that TR composite membranes exhibited a great water flux of 53 kg m-2 h-1 and salt rejection >99.97% at a temperature gradient of 50 °C. Moreover, the thermal efficiency increased from 60% for the pristine TR membrane to 68% for the TR composite membrane, highlighting the significant role of membrane structural architecture in enhancing vapor transport while minimizing conductive heat loss across the membrane. These results underscore the potential of TR PBOI membranes to bridge the gap between lab-scale development and industrial commercialization, offering a sustainable approach for high-salinity water desalination.

The recycling of spent lithium-ion batteries and selected complex electronic waste fractions is commonly evaluated using isolated metrics such as leaching yield, metal removal efficiency, and reagent consumption. However, this approach fails to address the central challenge of sustainable valorization: integrating upstream conversion with downstream selective recovery without shifting environmental and separation burdens. This review focuses specifically on spent LIBs as the primary model system, while also drawing insights from related e-waste streams (e.g., printed circuit boards and polymer-containing residues) where the interface-driven framework applies. It examines how key interfaces—solid–fluid, polymer–metal–fluid, membrane–solution, electrode–electrolyte, and crystal–solution—govern metal mobilization, selectivity, effluent quality, product purity, and scalability. Emphasis is placed on hydrothermal and supercritical water processing, PVC/CPVC (Polyvinyl Chloride/Chlorinated Polyvinyl Chloride)-assisted metal mobilization and membrane-based recovery techniques, including nanofiltration, membrane distillation, membrane distillation crystallization, ion exchange, and electrochemical methods. Supercritical water and membrane processes are complementary only when upstream chemistry is designed to facilitate downstream separation. PVC-rich waste is reconsidered as a reactive chlorine source, provided that corrosion, HCl formation, and salt precipitation are controlled. Critical gaps include incomplete mass balances, limited multicomponent studies, weak integration between process stages, and scarce techno-economic and life-cycle analyses. A roadmap is proposed for scalable, integrated hydrothermal–membrane systems enabling efficient resource recovery and water reuse.

This study investigates the integration of nanofiltration (NF) and membrane distillation (MD) for the selective separation and recovery of critical metals from effluents generated by supercritical water oxidation (SCWO) of lithium-ion batteries. Beyond resource recovery, the proposed hybrid system addresses the urgent environmental challenge associated with highly contaminated battery recycling effluents, which pose severe risks to aquatic ecosystems if improperly managed. NF90 and NF270 membranes exhibited complementary behavior: NF90 achieved high rejection of Co, Ni, and Mn (>70%) with a minimum lithium rejection of 30%, whereas NF270 showed lower rejection of divalent metals (40%) and lower lithium rejection (90%) and reducing the effluent conductivity by more than 85%. Surface characterization (SEM–EDS, AFM, BET, and contact angle) revealed fouling mechanisms and wettability loss, highlighting operational stability limitations. In this hybrid approach, nanofiltration enables the selective separation of lithium from transition metals, while membrane distillation promotes water recovery and concentrates lithium into a recoverable brine, with fouling and wetting defining the operational boundaries of the process. Overall, the results demonstrate that coupling SCWO with NF–MD represents a viable and scalable pathway for simultaneous effluent detoxification and lithium recovery, contributing to circular economy strategies and the sustainable management of battery-recycling wastewater.

Carbon recovery and sustainable management of sewage sludge from wastewater treatment plants were reviewed regarding the technical and market supply potentials, environmental, economic, and social benefits, and technology readiness. The findings were used in a case study of a 75 000 PE water recycling plant to evaluate the potential benefits of implementing the most promising technological solutions via a triple bottom line approach. Implementation of rotating belt filtration for cellulose recovery in primary treatment would reduce the energy required for aeration, the sludge volume and thus the sludge management burden. Recovery of protein from the waste activated sludge would provide net revenue. Volatile fatty acid (VFA) extraction from the acidogenic phase of anaerobic digestion was economically sound. Co-digestion of food waste with the sludge would enhance VFA production or biogas generation, depending on the target product. Microalgal treatment of the digestate liquor would enable purification of the biogas through CO₂ fixation and generate biomass which could be returned to anaerobic digestion for biogas production. Conversion of the biosolids to biochar would lead to net generation of revenue due to cost savings for transportation and land application, the biochar is useful for adsorption, catalysis and soil amendment for nutrients and sequestering CO₂. Integration of promising recovery technologies into wastewater treatment would reduce sludge volume and create value-added products, and also reduce the environmental impact and health risks. However, integration must address the obstacles in terms of economy, value chain development, environment and wellbeing, as well as societal and policy limitations.