Microplastics (MPs) are synthetic polymer particles whose surface properties are susceptible to environmental and physiological ageing; however, how physiological ageing in enzyme-containing gastric fluid alters clayey soil-microplastic interactions and metal retention remains poorly understood. This study investigated how ageing of three representative MPs in simulated gastric fluid (SGF; containing pepsin as the enzymatic component) altered their interactions with kaolin (a simplified clay mineral model) and affected Pb adsorption behaviours. SGF exposure induced detectable modifications in MPs’ surface chemistry in part due to protein corona deposition, strong acid erosion, and oxidation of functional groups. These modifications influenced the MP vector effects for Pb (notably, the adsorption capacity of digested tyre-MPs decreased by ~35.6%), as well as kaolin-MP interactions and the Pb adsorption capacity of the mixtures. Aggregation between MPs and kaolin particles reduced Pb adsorption relative to the expected additive effect, likely due to the formation of heterogeneous aggregates through electrostatic interactions and physical entrapment that masked potential Pb-binding sites. Notably, zeta potential differences among kaolin-MP mixtures correlated strongly with their Langmuir adsorption capacities (correlation coefficient r = 0.933), highlighting the role of electric double layer in governing Pb adsorption. From a geo-environmental perspective, Pb adsorption in the clay-rich mixtures may be altered not simply by the addition of MPs as extra sites, but by the aggregation behaviour, interfacial charge, and mineral binding-site accessibility of the mixtures.

Recovering metals from mineral-bound fractions remains a major challenge because these recalcitrant phases dominate metal-bearing wastes and render much of the metal inaccessible. We employed plant-microbial fuel cells (PMFCs) to mobilise and recover metal from such materials through a combination of mobilisation via root exudate leaching, low-power electrokinetic transport powered by the fuel cell and ultimately plant uptake. Here, we demonstrate that PMFCs can substantially enhance copper mobilisation and recovery from malachite (Cu₂CO₃(OH)₂)-spiked soils, as a model of metal-bearing mineral waste, using common reed (Phragmites australis). In soil-only systems, copper mobilisation was negligible. Application of low-power electrokinetics alone increased aqueous Cu concentrations only modestly. Plant-only systems enhanced mobilisation via root exudates. By contrast, PMFCs, combining plants with low-power electrokinetics, consistently outperformed both single processes: after two months, copper recovery by the plants reached 6.7 % of the initial load-1.8 times higher than in plant-only systems-with Cu mobilisation levels up to 20-fold greater as indicated by aqueous Cu concentration. These outcomes reveal a clear synergistic effect between root-exudate-driven lixiviation combined with the likely circuit-maintained reducing conditions and field-assisted transport, enabling enhanced recovery of copper from recalcitrant malachite. This study establishes PMFCs as a promising nature-based platform for sustainable remediation and resource recovery from recalcitrant metal-bearing wastes.

Energy storage is vital to buffer intermittency in power supplies comprised largely or wholly of variable sources (e.g. wind, solar) at large and small scale. Present technologies and those in development (e.g. electrochemical cells) have disadvantages (e.g. cost, resource use, chemical hazard) whilst the capacity required is extremely large and widely distributed. Storage is needed for burgeoning off-grid small-scale infrastructure such as sensor networks as well as larger scale power sources. To address challenges with current technologies we demonstrate the ability of the pedosphere to store electrical energy and act as a natural, biogeochemical battery. The pedosphere, consisting of porous geomaterials such as soil and sediment, is an extensive potential energy repository covering much of the Earth and underpins most infrastructure or situations where power is generated or required. This pre-existing capacity has the potential to simplify energy storage and the installation and management of power generating or consuming infrastructure.In this study the concept of such ‘geo-batteries’ is demonstrated. Controlled microbial synthesis of simple organic molecules in natural porous media (estuarine sediment) is shown, with this organic matter acting as an accessible form of energy storage. When combined with the employment of a microbial fuel cell to extract this energy electrically through degradation of the organic molecules, a battery is formed, with external control over energy input and output through switching of charging and discharging cycles.This project received funding from the UK Engineering and Physical Sciences Research Council, grant no. EP/X018865/1.

Flushed wet wipes pose a significant pollution risk to river systems at both macro and micro levels. However, the link between their emissions and environmental contamination remains unclear. Here we integrated emissions-based modelling with existing data on wet wipe disposal and microfibre generation to predict the quantity of emissions entering river systems and the transport pathways involved. Results indicate that wastewater pathways, including sewer overflows, wastewater treatment plants, and agricultural runoff, are major conduits for these pollutants. Despite advanced wastewater treatment, substantial microfibre emissions still enter the environment. Extrapolating to larger scales reveals wet wipe pollution as an international issue requiring urgent attention. This research offers a comprehensive modelling framework applicable to various wastewater pollutants, providing valuable insights for policymakers and the water industry. Improved data on wet wipe disposal, fate, and spatially distributed wastewater systems are necessary to pinpoint their environmental risks more accurately.

The environmental degradation and fate of cellulose-based 'biodegradable' wet wipes under real-world conditions remain underexplored, particularly in urban freshwater systems where they are frequently discharged via toilet flushing. Building on previous mesocosm-based experiment, this study quantified in-situ degradation of two commercially available cellulose-based wipes labelled 'biodegradable' across ten urban rivers and streams and identified key environmental drivers of degradation. Tensile strength loss was used as a proxy measurement for wipe degradation alongside cotton strip bioassays as ecological benchmarks. Wipes rich in natural cellulose degraded substantially faster (Brand A: 6.69 ± 3.19 % per day) than those dominated by regenerated cellulose (Brand B: 3.12 ± 1.93 % per day) or cotton bioassay controls (2.22 ± 1.00 % per day). Degradation rates were shaped by microbial biomass, total dissolved solids, temperature, and river-level fluctuations, although exposure duration had the largest effect - suggesting complex interactions between physical and biological processes. Despite early-stage degradation, most wipes persisted after five weeks, challenging their biodegradability claims. These findings highlight potential ecological risks from persistent textile fibre pollution, emphasising the need for updated labelling and biodegradability standards that appropriately reflect real-world freshwater conditions, as well as greater scrutiny of plastic-free alternative products and their environmental fates in general.

The environmental fate of cellulose-based "biodegradable" wet wipes in freshwater ecosystems remains poorly understood, despite growing market demand and legislative shifts banning plastic-containing alternatives. This study evaluated the degradation behaviour of two commercially available biodegradable wet wipe brands in upland stream mesocosms mimicking real-world river conditions. Using tensile strength loss (TSL) as the primary degradation metric, wipe degradation was compared across varied pH, temperature, nutrient, and light regimes, alongside cotton strip controls. Results revealed that although degradation rates varied by material and environmental context, both wet wipe brands persisted in river systems for 5 weeks, with Brand A degrading ∼50 % faster than Brand B and nearly twice as fast as cotton controls. Degradation was significantly influenced by pH, temperature, and total dissolved solids, but not by wipe positioning in the water column (hyporheic, submerged, surface) or microbial biomass alone. Temperature-adjusted TSL (% per degree day) emerged as the most robust degradation metric, suggesting initial physical disintegration preceded microbial breakdown. These findings challenge current biodegradability claims and highlight the need for regulatory testing under environmentally relevant freshwater conditions to ensure truly biodegradable wet wipe products.

Water-soluble polymers (WSPs) are additives used as thickeners, stabilisers and flocculants in industry and in household products, including personal care products. Given their widespread use, it is likely WSPs enter the environment, particularly through wastewaters. This is of concern as there is little ecotoxicological research on their fate and behaviour once in the environment, which means their risk to aquatic life is not understood. The lack of suitable analytical techniques to detect, characterise and quantify WSPs hinders research on the potential impact of these polymers. A novel method has been developed that identifies polymers within a sample and separates them using gel-permeation chromatography (GPC). This is coupled with matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS), to quantify the polymer fractions using molecular weight information. This process has been carried out on a range of aqueous media. Polyethylene glycol (PEG) ingredients were successfully separated from non-polymeric material in a commercial shaving gel personal care product (PCP), before being quantified at 1.62 wt%. This method was applied to a spiked wastewater influent sample to demonstrate the extraction and separation of PEG from organic constituents such as dissolved organic matter (DOM). This highlighted the additional challenges of analysing WSPs in the environment, as factors such as sorption and biodegradation affected the total recovery of PEG, with an extraction efficiency of 53%. Overall, this method was applied for the extraction of PEG from a PCP with accurate quantification, before a proof-of-concept extraction from wastewater demonstrated the difficulties associated with WSP analysis in environmental samples. This method provides opportunities to use tandem GPC/MALDI-TOF MS to quantify WSPs in a broad array of environmental samples. Additional studies could include its application to wastewater or freshwater monitoring.

The water-soluble polymer polyvinylpyrrolidone (PVP) is an established ingredient in pharmaceutical and personal care product (PPCP) formulations. Due to its high usage and lack of biodegradability, it has been detected up to 7.0 mg L -1 in wastewater and 0.1 mg L -1 in the receiving freshwaters, with several studies showing detrimental sublethal effects in a range of aquatic species. A lack of simple analytical methods to detect and quantify PVP currently impacts further investigation into the cause of these sublethal effects. In this paper we propose a refractive index gelpermeation chromatography (GPC) method to quantify PVP, which includes the processing of raw chromatograms using line deconvolution to calculate peak area. The method was then applied to Daphnia magna exposed to PVP for 48 h. A limit of detection (LOD) and limit of quantification (LOQ) of 0.05 and 0.2 mg mL -1 respectively was determined, with a recovery of 78 % from spiked Daphnia magna . PVP was detected in the samples above the LOD but below the LOQ. This suggests PVP is ingested by Daphnia magna , which warrants further investigation into whether bioaccumulation of PVP could be causing the sublethal effects seen in other studies.

Water quality variation in semi-enclosed urban coastal areas with different pollutant sources is a substantial issue. Pollutant entrapment has a significant impact on the lives of the local people. Surface water quality modelling often requires large datasets covering bathymetry, fluid and pollutants boundary conditions, sources and sinks. This is particularly challenging in regions with complex features and poor data availability, such as coastal water bodies featuring a large number of widely distributed islands and estuaries. In this paper, we developed a model of surface water quality and hydrodynamics for Ha Long Bay, in the North of Vietnam and includes 1,969 islands, for a one-year period using a water quality dataset obtained for this study. The model utilized extracted bathymetric and geometric data from Admiralty Charts and Admiralty Tide Tables. Water quality coupled with the TELEMAC Model (WAQTEL) Biomass Module was employed to predict pollutant transport in the domain using point and diffused sources while field studies were conducted to collect data for the setting up and calibration of the water quality model. Thirty scattered sampling points were selected, and the water quality parameters were measured during two campaigns. The predicted water level and velocity values matched the local observation data well with a small error (RMSE = 0.19 and 0.16). Both NO3--N and PO43--P were high near the shoreline and decrease gradually offshore. The maximum concentrations of NO3--N and PO43--P reached 0.476 mg/L and 0.048 mg/L at the end of 2021 with the RMSE = 0.13 and 0.011, respectively. The levels of NO3--N and PO43--P and their distributions showed that Ha Long Bay was eutrophic even during the COVID-19 lockdown period.

Integrating ecosystem services and life cycle assessment is gaining increasing attention for the analysis of environmental costs and benefits associated with human activities covering multiple geographical scales and life cycle stages. Such integration is particularly relevant for evaluating the sustainability of nature-based solutions. However, merging these methods introduces additional uncertainties. This paper introduces a novel protocol to assess uncertainties in combined ecosystem services-life cycle assessment, focusing on ecosystem services accounting, life cycle inventory of foreground systems, and life cycle impact assessment characterisation factors. Applied to a nature-based solution case study compared to no-action and energy-intensive scenarios, the uncertainties were analysed using multi-method global sensitivity analysis. The robustness of the analysis results was assessed through convergence plots and statistical tests. Findings reveal significant uncertainties, especially in life cycle impact assessment characterisation factors, with the extent varying by impact category. Uncertainties in foreground life cycle inventory, particularly in land use of nature-based solutions scenario, are also notable. Compared to these, uncertainties associated with indicators of impact on ecosystem services (uncertainty arising from input variability in ecosystem services accounting) are relatively lower. This study underscores the critical role of uncertainty assessment in enhancing the reliability of integrated assessments for nature-based solutions, providing a framework to identify and quantify key uncertainties, thereby supporting more informed decision-making.

The management of high-volume (HV) waste poses a persistent challenge in sustainable materials management and represents an untapped opportunity in circular economy models. This study proposes a conceptual decision-making framework to operationalise a novel circular economy strategy for HV waste, involving temporary storage to facilitate nature-based secondary resource recovery. Using an illustrative case study of a candidate HV waste (legacy mining waste), we apply a robust multi-objective spatial optimisation approach at a national scale, employing an exact solution approach. Our methodology integrates mixed-integer linear programming to evaluate the economic viability, social benefits, and impacts of climate change uncertainties on nature-based solutions (NbS) implementation across diverse scenarios. The results demonstrate that NbS can enhance economic feasibility by incorporating carbon sequestration and employment benefits while demonstrating resilience against climate change projections to ensure long-term sustainability. The findings suggest that although NbS can improve the circular economy of HV nationally, it is essential to assess additional ecosystem services and address multiple uncertainties for effective macro-level sustainability assessment of HV management. This study offers a robust decision-making framework for policymakers and stakeholders to plan and implement nature-based circular economy strategies for HV waste streams at a national level while effectively managing long-term planning uncertainties.

Consumer wet wipes sold as biodegradable and flushable have tripled in market size in the last decade (>$3 billion in 2022), spurred by concerns over their potential harmful impact. Whilst predominantly composed of cellulosic fibres such as cotton, rayon, or wood pulp, these have been found to persist in sewers and in the environment in near equal abundance to their ‘synthetic’ counterparts. This questions whether flushed biodegradable wet wipes really degrade. Working from first principles, we therefore explore the physicochemical composition, environmental interactions, and degradation processes throughout the entire life cycle of cellulosic wet wipe fibres, from production to environmental fate, to understand their degradation behaviour in wastewater and freshwater systems. The results highlight that >50 % of biodegradable and flushable wipes are commonly manufactured with both biological biodegradable cellulose-based fibres and low-degradable synthetic fibres, and that they contain various property-enhancing chemical additives that can limit degradation. Whilst cellulose fibres in wet wipes are highly prone to physical fragmentation, their molecular degradation is difficult within the environment. This is due to the physicochemical manufacturing properties of wet wipes and the usually inadequate ambient conditions for its breakdown, creating persistent and possibly biologically harmful microfibres. We conclude that currently, most flushed biodegradable wet wipes do not really degrade, and that more empirical investigations are needed on their in-situ degradation behaviour and the environmental and manufacturing processes that may influence this breakdown. In doing so, full life cycle approaches to wet wipes should be adopted, considering their manufacturing properties, consumer disposal behaviour, and environmental implications.

Nature-based solutions (NbS) have gained significant attention as a promising approach for remediating contaminated lands, offering multiple ecosystem services (ESs) benefits beyond pollution mitigation. However, the quantitative sustainability assessment of NbS remediation systems, particularly with regard to post-remediation impacts, remains limited. This mini-review aims to address the existing gaps in the assessment of NbS remediation systems by evaluating the limitations of life cycle assessment (LCA) and cost-benefit analysis (CBA) methodologies. A systematic literature search was conducted resulting in the review of 44 relevant studies published between 2006 and 2023. The review highlights an increasing trend in the coverage in the sustainability assessment literature of NbS remediation systems. Phytoextraction was identified as the main NbS mechanism employed in 65 % of the reviewed works, targeting contaminants such as heavy metals and hydrocarbons. However, the post-remediation aspects, including impacts on ESs and the end-of-life management of NbS biomass, were often neglected in the assessments with only a subset of studies partially exploring such aspects. The findings underscore the need for a comprehensive and integrated approach to assess the sustainability of NbS remediation systems, including the incorporation of economic factors, site-specific considerations, and post-remediation impacts. Addressing these gaps will enhance the understanding of NbS effectiveness and facilitate informed decision-making for contaminated land remediation.

Nature-based solutions (NbS) are increasingly recognized as a sustainable alternative to conventional remediation for brownfield redevelopment. One of the key advantages of NbS is that they provide ecosystem services (ES) during and after remediation. However, traditional Life Cycle Assessment (LCA) does not fully account for the advantages of ES. To address this limitation, we propose a holistic sustainability assessment framework that integrates ES valuation and LCA for brownfield redevelopment planning. The framework is designed to support decision-making by providing a comprehensive environmental analysis of the impacts of different remediation scenarios. The proposed framework is applied to the London Olympic Park mega remediation project as a case study. Three considered scenarios are a business-as-usual scenario, a conventional remediation scenario, and an NbS scenario. The primary and secondary impacts of each scenario, the temporal efficacy of remediation, and the impact on ES are evaluated using the framework. The results suggest that the NbS scenario provides the best trade-off between mitigating contamination risks and economic costs within a reasonable timeframe due to the added benefits of ecosystem services. Overall, the proposed framework provides a comprehensive approach that considers the multiple aspects of environmental sustainability.

Many countries face serious strategic challenges with the future supply of both aggregates and critical elements. Yet, at the same time, they must sustainably manage continued multimillion tonne annual arisings of mineral-dominated wastes from mining and industry. In an antithesis of Circular Economy principles, these wastes continue to be landfilled despite often comprising valuable components, such as critical metals, soil macronutrients and mineral components which sequester atmospheric CO2. In this paper, the authors aim to introduce a new concept for value recovery from mineral-rich wastes where materials are temporarily stored and cleaned in landfill-like repositories designed to be mined later. The time in storage is utilised for remediating contaminated materials and separating and concentrating valuable components. It is proposed that this could be achieved through engineering the repository to accelerate "lithomimetic " processes, i.e. those mimicking natural supergene processes responsible for the formation of secondary ores. This paper summarises the concept and justifications and outlines fundamental aspects of how this new concept might be applied to the design of future repositories. The proposed concept aims to end the current "linear " landfilling of mineral-rich wastes in favour of reuse as aggregates and ores.

Landfill mining has received major attention in recent years for the reclamation of waste disposal sites, including in developing countries such as India where significant efforts are being made to manage sites in this way. The bulk of the material obtained from landfill mining consists of fine-grained soil-like material (SLM) but its direct reuse in off-site applications is restricted due to the presence of harmful heavy metals, soluble salts and other pollutants. In this study, appropriate techniques for managing SLM to permit recovery and reuse are assessed. As a result, experimental investigation explores the efficacy of two remediation techniques considered appropriate for SLM management: electrokinetic remediation and phytoremediation. These were applied to SLM from a recently mined landfill and their ability to reduce heavy metal and other soluble salt burdens assessed. Electrokinetic remediation has shown considerable potential to mobilise and transport heavy metals and soluble salts through and from the SLM over an eight-week period. Phytoremediation experiments also demonstrated mobilisation and uptake of metals from the SLM over a similar duration although relatively low amounts were recovered as a result of the low biomass produced over this period. Both technologies have demonstrated potential for recovery of metals from SLM, as well as recovering the SLM itself as a potential resource.

Improper disposal of lignocellulosic wastes may produce a large quantity of greenhouse gases and pollute the environment. Through anaerobic digestion processes, lignocellulosic wastes can be recycled to produce clean and renewable biogas. However, the lignin in lignocellulose limits its potential as such a biomass resource, and the efficacy of biogas production is not satisfactory although recent research efforts have attempted to address this issue. In this review, the physicochemical characteristics of three lignocellulosic wastes, including municipal solid waste, forestry waste, and crop straw, are summarized. Then, the mechanism and influencing factors of biogas production from these wastes through anaerobic digestion are presented. Biological pretreatment techniques have been confirmed to increase lignocellulose hydrolysis and then enhance biogas production, among them, co-culture systems, metabolic engineering and anaerobic co-digestion are worthy of focus in future research. Furthermore, natural lignocellulose degrading systems, like xylophagous insects and ruminants, also have potential for improving the anaerobic digestion system. This review also considers the future perspective of anaerobic digestion of lignocellulosic wastes, including kinetics and model studies to optimize anaerobic digestion process, and policy to facilitate biogas production from lignocellulosic wastes. This article aims to comprehensively review challenges with anaerobic digestion of lignocellulosic wastes and summarize available pretreatment methods focusing mainly on biological techniques to find efficient and low-cost strategies for improving the anaerobic digestion process and biogas production.

Self-healing construction materials have caused great interest in the last decade due to their several applications for civil engineering. A self-healing material is defined as an artificial or synthetically created material that has the built-in ability to repair damage to itself without human intervention

The ground is a natural grand system; it is composed of myriad constituents that aggregate to form several geologic and biogenic systems. These systems operate independently and interplay harmoniously via important networked structures over multiple spatial and temporal scales. This paper presents arguments and derivations couched by the authors, to first give a better understanding of these intertwined networked structures, and then to give an insight of why and how these can be imitated to develop a new generation of nature-symbiotic ground engineering techniques. The paper draws on numerous recent advances made by the authors, and others, in imitating forms (e.g. synthetic fibres that imitate plant roots), materials (e.g. living composite materials, or living soil that imitate fungi and microbes), generative processes (e.g. managed decomposition of construction rubble to mimic weathering of aragonites to calcites), and functions (e.g. recreating the self-healing, self-producing, and self-forming capacity of natural systems). Advances are reported in three categories of Materials, Models, and Methods (3Ms). A novel value-based appraisal tool is also presented, providing a means to vet the effectiveness of 3Ms as standalone units or in combinations.