Nanobubble aeration enhanced wastewater treatment and bioenergy generation in constructed wetlands coupled with microbial fuel cells

Mechanism of Charged Graphene Substrate Effects on the Stability of Interfacial Nanobubbles: Molecular Dynamics Simulations

Charged solid substrates play a crucial role in influencing the behavior of interfacial nanobubbles, although the underlying mechanisms are not yet fully understood. To explore this process in greater depth, we employed molecular dynamics (MD) simulations to systematically examine the effects of charged graphene on the morphological evolution, solid interface structure, and stability of interfacial nanobubbles, thereby revealing the intrinsic mechanisms. Our findings indicate that as surface charge density increases, the gas-solid interactions gradually diminish while the liquid-solid interactions significantly intensify. This results in a progressive reduction in both the contact angle and radius of the nanobubbles, eventually causing their detachment from the substrate and transformation to bulk-phase nanobubbles. Moreover, the enhanced gas accumulation effect at the solid interface leads to a reduction in the internal pressure of the bubbles, thus improving the stability of the interfacial nanobubbles. Additionally, the increase in the surface charge density elevates the water molecule density at the solid interface, which in turn strengthens the hydrogen bond network of interfacial water molecules, further stabilizing the liquid-solid interface structure. In summary, this study highlights the critical role of surface charge in regulating interfacial nanobubble behavior, providing new theoretical guidance for optimizing electrode materials and controlling bubble behavior in electrochemical systems.

Delineating the fundamental attributes and traits of nature-based solutions in wastewater management

Water stress, exacerbated by population growth and climate change, necessitates sustainable wastewater management solutions that promote resource recovery and environmental protection. Nature-Based Solutions (NBS) offer a viable alternative to conventional wastewater treatment by leveraging natural processes for water purification and ecosystem restoration. However, the lack of standardised criteria for defining and evaluating NBS in wastewater management has led to inconsistencies in research and practice. This study conducts a systematic review of NBS applications in wastewater treatment, using Scopus and Web of Science databases, to delineate their fundamental attributes and establish a structured evaluation framework. By assessing NBS against seven key characteristics, i.e., natural processes, sustainability and resilience, biodiversity enhancement, multifunctionality, community and stakeholder involvement, cost-effectiveness and engineering approach, this study provides a comprehensive framework for distinguishing genuine NBS from other nature-inspired interventions. The findings contribute to improving the scientific rigour of NBS classifications, ensuring their scalability and fostering their integration into environmental management. This study offers a novel methodological approach to evaluating the effectiveness and applicability of NBS in wastewater management, facilitating their broader adoption and guiding future policy and research directions.

Clinical Applications of Micro/Nanobubble Technology in Neurological Diseases

Nanomedicine, leveraging the unique properties of nanoparticles, has revolutionized the diagnosis and treatment of neurological diseases. Among various nanotechnological advancements, ultrasound-mediated drug delivery using micro- and nanobubbles offers promising solutions to overcome the blood-brain barrier (BBB), enhancing the precision and efficacy of therapeutic interventions. This review explores the principles, current clinical applications, challenges, and future directions of ultrasound-mediated drug delivery systems in treating stroke, brain tumors, neurodegenerative diseases, and neuroinflammatory disorders. Additionally, ongoing clinical trials and potential advancements in this field are discussed, providing a comprehensive overview of the impact of nanomedicine on neurological diseases.

Comprehensive review of technologies for separate digestate treatment and agricultural valorisation within circular and green economy

Anaerobic digestion (AD) has the potential to catalyse the shift from a linear to a circular economy. However, effective treatment and management of both solid (DSF) and liquid (DLF) digestate fraction treatment and management require adopting sustainable technologies to recover valuable by-products like energy, biofuels, biochar, and nutrients. This study reviews state-of-the-art advanced technologies for DSF and DLF treatment and valorisation, using life cycle assessment (LCA) and techno-economic analysis (TEA) in integrated digestate management (IDM). Key findings highlight these technologies' potential in mitigating environmental impacts from digestate management, but there's a need to improve process efficiency, especially at larger scales. Future research should prioritize cost-effective and eco-friendly IDM technologies. This review emphasizes how LCA and TEA can guide decision-making and promote sustainable agricultural practices. Ultimately, sustainable IDM technologies can boost resource recovery and advance circular economy principles, enhancing the environmental and economic sustainability of AD processes.

Advancing nanobubble technology for carbon-neutral water treatment and enhanced environmental sustainability

Gaseous nanobubbles (NBs) with dimensions ranging from 1 to 1000 nm in the liquid phase have garnered significant interest due to their unique physicochemical characteristics, including specific surface area, low internal gas pressure, long-term stability, efficient mass transfer, interface potential, and free radical production. These remarkable properties have sparked considerable attention in the scientific community and industries alike. These hold immense promise for environmental applications, especially for carbon-neutral water remediation. Their long-lasting stability in aqueous systems and efficient mass transfer properties make them highly suitable for delivering gases in the vicinity of pollutants. This potential has prompted research into the use of NBs for targeted delivery of gases in contaminated water bodies, facilitating the degradation of harmful substances and advancing sustainable remediation practices. However, despite significant progress in understanding NBs physicochemical properties and potential applications, several challenges and knowledge gaps persist. This review thereby aims to summarize the current state of research on NBs environmental applications and potential for remediation. By discussing the generation processes, mechanisms, principles, and characterization techniques, it sheds light on the promising future of NBs in advancing environmental sustainability. It explores their role in improving oxygenation, aeration, and pollutant degradation in water systems. Finally, the review addresses future research perspectives, emphasizing the need to bridge knowledge gaps and overcome challenges to unlock the full potential of this frontier technology for enhanced environmental sustainability.

Exploring a chemical input free advanced oxidation process based on nanobubble technology to treat organic micropollutants

Advanced oxidation processes (AOPs) are increasingly applied in water and wastewater treatment, but their energy consumption and chemical use may hinder their further implementation in a changing world. This study investigated the feasibility and mechanisms involved in a chemical-free nanobubble-based AOP for treating organic micropollutants in both synthetic and real water matrices. The removal efficiency of the model micropollutant Rhodamine B (RhB) by oxygen nanobubble AOP (98%) was significantly higher than for air (73%) and nitrogen nanobubbles (69%). The treatment performance was not significantly affected by pH (3-10) and the presence of ions (Ca2+, Mg2+, HCO3-, and Cl-). Although a higher initial concentration of RhB (10 mg/L) led to a slower treatment process when compared to lower initial concentrations (0.1 and 1 mg/L), the final removal performance reached a similar level (∼98%) between 100 and 500 min. The coexistence of organic matter (humic acid, HA) resulted in a much lower reduction (70%) in the RhB removal rate. Both qualitative and quantitative analysis of reactive oxygen species (ROSs) using fluorescent probe, electron spin resonance, and quenching experiments demonstrated that the contributions of ROSs in RhB degradation followed the order: hydroxyl radical (•OH) > superoxide radical (•O2-) > singlet oxygen (1O2). The cascade degradation reactions for RhB were identified which involve N-de-ethylation, hydroxylation, chromophore cleavage, opening-ring and final mineralisation processes. Moreover, the treatment of real water samples spiked with RhB, including natural lake water and secondary effluent from a sewage works, still showed considerable removals of the dye (75.3%-90.8%), supporting its practical feasibility. Overall, the results benefit future research and application of chemical free nanobubble-based AOP for water and wastewater treatment.