Securing critical raw materials for net-zero energy systems and green technologies, has become a global priority. This urgency is fuelled by increasing demand, dwindling natural reserves, and rising geopolitical instabilities. Urban waste streams, often rich in metal concentrations than natural ores, are emerging as viable alternative for metal recovery. Bioleaching, a natural process utilising microorganism to mobilise metals from solid mineral matrices, has become increasingly popular as a sustainable and economically attractive alternative to conventional mining of minerals, particularly for low-grade ores and waste-derived feedstocks. The attractiveness of bioleaching lies in low environmental impact and high efficiency, even at low metal concentrations. This review explores different metal-bearing secondary materials containing critical, precious, and rare earth elements (REEs) as potential feedstocks for bioleaching. It traces the evolution of bioleaching from natural ore processing to its growing utility in urban waste valorisation within a circular economy framework. It compares bioleaching process in natural ores versus urban waste, while showcasing recent advancements toward commercial implementation. The review also identifies existing challenges and proposes strategies for improvement. Finally, it articulates bioleaching's potential for integration into a circular economy model, emphasising its role in enabling sustainable metal recovery and achieving carbon neutrality goals.

This paper explores the use of 3-compartment and 2-compartment electrodialytic (ED) cells for the simultaneous extraction and separation of P and heavy metals from freshwater sediments, to recover a P-product without heavy metals and sediments fit for recycling. Eutrophic sediments from two different freshwater sources, one less contaminated and one highly contaminated with heavy metals, were used. The extraction of heavy metals (Cd, Cr, Cu, Ni, Pb, Zn) was higher from the highly contaminated sediment than from the less contaminated one. The ED treatment (3-compartment and 2-compartment) of both sediments obtained the highest extraction for Zn (about 85 %) and the lowest for Cr (2 - 11%), whereas the extraction of P was between 35 and 50 %. The separation and extraction of P and heavy metals was better with the 3-compartment ED cell than the 2-compartment ED cell, potentially allowing the utilization of the P-extracted solution. Sequential extraction was performed to assess the operationally defined pools of P and heavy metals that could be extracted during the ED treatment. HCl-soluble P was fully extracted during ED treatment. Heavy metals associated with the exchangeable and reducible fractions were extracted significantly, and those with the oxidizable fraction were only partially extracted. After the ED treatment, the less contaminated sediment was suitable for recycling, for eg. as a soil improver, but not the highly contaminated sediment. Optimization of ED treatment is suggested to enhance the extraction of P and heavy metals, especially from the dominant and difficult-to-mobilize oxidizable fraction.

Re-mining unextracted metals from mine tailings can contribute to sustaining society's high demand for metals. Electrodialysis (ED) is a promising, yet underdeveloped, extraction technology for mobilizing and transporting particle-bound elements in a suspension slurry. This study investigated ED for extraction of copper (Cu), lead (Pb) and zinc (Zn) from Cu mine tailings (concentration of Cu: 2039 mg/kg, feldspar-dominant) and Pb-Zn mine tailings (Pb: 4469 mg/kg, Zn: 19417 mg/kg, dolomite-dominant). A multivariate experimental design was used to examine the effect of varying current density (1-5 mA/cm2) 2 ) and operation time (24-336 h) of 40 bench-scale experiments. The maximum extractions obtained were 70 % Cu from the Cu mine tailings and 97 % Pb and 88 % Zn from the Pb-Zn mine tailings. Depending on the tailing, the extraction was influenced differently by current density and operation time. In particular, carbonate minerals such as dolomite and calcite delayed acidification and thus the extraction due to their buffering capacity. However, as the carbonaceous tailings contained a larger proportion of soluble metals, likely to be bound in the carbonates themselves, overall higher metal extraction was obtained from these. Thresholds above, for which the increase of current densities did not increase extraction, were observed at 2 and 4 mA/cm2 2 for the Cu and Pb-Zn tailings, respectively. The solubility of the remaining metals in the treated tailings increased significantly due to acidification by the EDR process and utilization of the treated tailings in construction materials therefore needs further investigation.

AbstractMicrobes experience high cell density in many environments that come with diverse resource limitations and stresses. However, high density physiology remains poorly understood. We utilized well-controlled culturing systems to grow wild-type and metabolically engineeredEscherichia colistrains into high cell densities (50–80 g Cdry cell weightL-1) and determine the associated transcriptional dynamics. Knowledge-enriched machine-learning-based analytics reveal distinct stress-related gene expression patterns that are consistent with a fundamental trade-off between resistance and persistence. We suggest that this trade-off explains observed growth arrests in high-density cultures and that it results from the disruption of cellular homeostasis, due to reallocation of limited cellular resources from resistance functions towards maintenance requirements of engineered production pathways. This study deepens our understanding of high-density physiology and demonstrates its importance to fundamental biomanufacturing challenges.

The European Union Drinking Water Directive aims to protect human health and promote safe water consumption. The 2020 revision, Article 17 in particular, directed member states to provide public access to information on drinking water. This update was a response to citizen initiatives calling for the active participation of end-users in water services and greater transparency from water utilities. Difficulties implementing previous versions of the directive have highlighted divergences between policy purposes, local capacity to implement, and public response. These divergences are explored within eight case studies in Nordic countries and analysed using the policy implementation framework. We employed a mixed-method, multi-stage approach. Policy formulation was characterized through a literature review, policy design by the synthesis of legislative instruments, and policy implementation via an analysis of delivery behaviour based on interviews. We identified the main drivers of the directive's update and contrast these with the ongoing implementation process in the countries of study. Our results point to a differential and highly contextual implementation, which differs from the primary drivers of the policy update, namely, the establishment of public confidence in water services.

Microbes experience high cell density in many environments that come with diverse resource limitations and stresses. However, high density physiology remains poorly understood. We utilized well-controlled culturing systems to grow wild-type and metabolically engineered Escherichia coli strains into high cell densities (50–80 g C dry cell weight L-1) and determine the associated transcriptional dynamics. Knowledge-enriched machine-learning-based analytics reveal distinct stress-related gene expression patterns that are consistent with a fundamental trade-off between resistance and persistence. We suggest that this trade-off explains observed growth arrests in high-density cultures and that it results from the disruption of cellular homeostasis, due to reallocation of limited cellular resources from resistance functions towards maintenance requirements of engineered production pathways. This study deepens our understanding of high-density physiology and demonstrates its importance to fundamental biomanufacturing challenges. ### Competing Interest Statement The authors have declared no competing interest.

This study identified the heavy metal (HM) leaching from mine tailing blended mortar (MTBM) under different environmental exposure conditions to understand the risk of utilizing mine tailings as mineral additives. Eight mine tailings (MT) and MTBM (5 % cement replacement) were exposed to three different leaching tests: water leaching (one-stage batch leaching test), multi-environmental (sequential extraction) and pH-dependent leaching, to assess the leaching of copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn). The highest water and pH-change-induced HM leaching occurred from MT with high HM contents. The water leaching from MT was proportional to the solid content of the MT and thus not significantly impacted by the specific mineralogy of the tailings. Increased metal leaching compared to water leaching was observed when pH changed both from MT and MTBM. MTBM showed low or similar leaching to the reference. Mortar retained Cu, Ni, and Zn beyond what could be explained by mere dissolution. In contrast, the fraction of Pb leaching increased when incorporated into mortar. Leaching from MTBM depended more strongly on the HM than on the MT characteristics. Conducting comprehensive leaching assessments to evaluate the environmental risks is thus particularly important for Pb-rich MT utilization in construction materials.

Plastic litter is ubiquitous in the Arctic marine environment, but knowledge of the importance of specific sources is limited. This project aimed to investigate the input of plastic from untreated sewage discharged to the sea in Greenland. A method was developed to sample and quantify inputs of plastic in different size fractions from wastewater from two towns in Greenland. Plastic findings were visually characterized in terms of abundance, morphology, size, and chemically by characterizing the polymer composition using FTIR spectroscopy. The wastewater was found to be a source of both macro- and micro-sized plastic pollution. Of the total litter load, 70% of the mass was from plastic items larger than 25 mm. Wet wipes were found to be dominating and constituted 59% of the total emitted plastic by mass, but other sanitary items (sanitary pads and condoms) were also detected. A polymeric characterization of the macro-items by ATR-FTIR revealed that the wet wipes were mainly of PET (polyethylene terephthalate, a polyester) but also viscose and cellulose wet wipes were detected. In the microplastic fraction (<300 mu m), the main contributor was PP (polypropylene; 65%), but also PE (polyethylene), PES (polyester), PS (polystyrene), cellulose and other polymers were detected. A characterization of the microfibers revealed a large contribution of white/transparent fibers that primarily were composed of cellulose (67%) while a smaller fraction (10%) was polyester (PES), including polyethylene terephthalate (PET). The findings of white/transparent microplastic fibers in the wastewater suggest that a fraction of these fibers is directly related to the presence of the cellulose, viscose and PET wet wipes. Our results suggest that implementing either regulatory or behavioral measures to prevent wet wipes from entering the wastewater or using technical solutions to eliminate the discharge of wet wipes into the marine environment via wastewater, could significantly reduce the emission of plastics of all sizes from wastewater to the marine environment.

Seaweed from Greenland has potential as a food source. However, human sewage is discharged directly to the sea in the vicinity of the communities, a practice which could lead to the seaweed becoming contaminated by human pathogens. The objective of this study was to investigate the effect of wastewater discharge on the bacterial communities of wild populations of Fucus sp. sampled in the tidal zones in the vicinity of Sarfannguit, a smaller settlement (∼110 inhabitants) with limited discharge, and Sisimiut, Greenland’s second biggest town (∼5500 inhabitants). Fecal indicator bacteria (coliforms, Escherichia coli and the human fecal molecular marker HF183 [Fucus sp. only]) were consistently detected on Fucus sp. and in seawater from Sisimiut. In contrast, coliforms and E. coli were only detected once in samples collected close to the waste dump site in Sarfannguit. Presence of fecal indicator bacteria in seawater and on Fucus sp. coincided, indicating the utility of surveying seawater. MALDI-TOF mass spectrometry analysis of bacterial isolates identified fish and human pathogens on seaweed from Sisimiut while >80% of isolates from Sarfannguit could not be identified using existing data bases. Amplicon sequence variants belonging to Rhodobacteraceae and Flavobacteriaceae were dominant families in all Fucus sp. samples. However, wastewater discharge effected major changes in the overall composition of the seaweed microbiota as evidenced by analysis of the beta diversity. In conclusion, the microbiota on Fucus sp. harvested in the intertidal zones in a small, relatively unimpacted community, and close to the wastewater discharge of a larger community showed marked differences and the presence of human pathogens on sewage impacted Fucus sp. from the large community. It is recommended that microbiological criteria and guidelines regarding suitable seaweed harvest and cultivation sites be established, especially considering potential sources of anthropogenic impact on the local marine environment.

Small water supplies face similar problems worldwide, regardless of ownership or management type. Non-compliance with water quality regulations is more frequent in small supplies than in large ones, as are waterborne disease outbreaks. The new European Union Drinking Water Directive requires risk-based approach (RBA) to secure water safety as is recommended in the World Health Organization's Guidelines for drinking water quality through 'water safety plans'. This is already in regulation in the Nordic countries, although less used in small supplies. In this research, we explore the challenges, barriers and possible solutions to implementing RBA and improving compliance in small supplies. This was achieved by conducting and analysing interviews with 53 stakeholders from all eight Nordic countries to produce recommendations for action by the different implicated actors. Our findings suggest the centrality of governmental policy, including support for continuous training, provision of simple RBA guidelines and increasing cooperation in the water sector. The Nordic experience reflects global challenges with small water supplies and the trend towards systematic preventive management epitomized in the framework for drinking water safety advocated by the World Health Organization since 2004.

The low proportion of households with piped drinking water in Greenlandic settlements - and elsewhere in the Arctic, leads to improvised methods of household water storage and water saving practices that could present a risk for public health. This interview-based study investigated the perceptions of safety and acceptability of the water supply in rural Greenlandic households. The bacterial quality of the water distributed by the public supply before and after storage in the homes, of alternative water sourced from nature by the users themselves, and of shared handwash basins used in un-piped homes, was analyzed. The treated water distributed by the rural Greenlandic water supply was acceptable to most users, although half of them expressed concerns about its quality, and distrusted the state of the infrastructure delivering piped water. For drinking, most respondents preferred untreated water from nature, but a majority used mainly piped water for practical reasons of access. The microbial quality of the public water supply met legislative requirements in most cases, but was found to deteriorate during both distribution to some taps, and storage in the homes, which constitutes a challenge to the reliable provision of safe water to users. Water from alternative sources showed slightly higher heterotrophic plate counts (HPC) than piped water, but no Escherichia coli . As for washbasins, they were found to have high levels of contamination in all three bacterial parameters investigated (HPC, coliforms and E. coli ), indicating a possible transmission route for pathogens. In conclusion, while the quality of treated water was overall good at distribution, the water saving and storage practices developed to compensate for the lack of piping may threaten public health. Alternative water sources are culturally important and trusted by users, although the possible impact of changes in climate and land use on the reliability of their quality is unknown.

Phosphorus is a critical, irreplaceable raw material, and developing methods to recover P from secondary sources such as sewage sludge ash (SSA) is crucial. Two-compartment electrodialytic extraction (2C-ED) is one method where an electric DC field is applied to extract P and separate heavy metals simultaneously. Several process parameters influence 2C-ED, and they influence each other mutually. This paper explores chemometrics modeling to give insight into the 2C-ED process and, specifically, optimization of the experimental parameters towards 80% P extraction. A projections-to-latent-structures model was constructed based on new 2C-ED experiments conducted with one SSA type. The model was stable (high correlation factor and predictive power). Variable importance in the projection (VIP) plots showed that the influence of the variables was in the order: current > duration > L:S ratio > stirring velocity > dispersion solution (weak acid or distilled water). Contour plots were used for exploring different P extraction strategies. For example, more P mass per unit current was extracted at an L:S ratio of 7 compared to L:S 14. This shows that treating a thicker SSA suspension is preferable to optimize the current efficiency. The chemometric model proved valuable for optimizing the 2C-ED process and future scale-up.

Global efforts are still under way to ensure sustainable development goal 6 of providing enough clean water to sustain public health in many regions, and especially in the Arctic where the remoteness of communities and the harsh climate make water provision especially challenging. This study aimed to examine the sufficiency, accessibility, and affordability of water supplies in rural Greenland. The state of the water supply was investigated using quantitative data on infrastructure and demographics. Qualitative data on water-related practices and perceptions were collected through fieldwork and interviews in a selection of settlements. Generally, the supply of drinking water was found to be sufficient and affordable for most. However, access was severely constrained by the lack of piping to rural homes (20% were piped). The daily water consumption of residents from un-piped households was between 13 and 23 L/d/cap, i.e. within the basic access level according to WHO, which is in theory not sufficient to sustain public health. Several health risks could be caused by the low daily consumption in un-piped homes, and water saving practices induced by it - i.e. the use of shared handwashing basins, and household water storage, which could lead to degradation of water quality at the point-of-use.

At present, there are no standardised tests to assess metal leaching during submarine tailings discharge. In this study the influence of variables known to affect metal mobility and availability (dissolved organic carbon (DOC), pH, salinity, temperature, aerated/anoxic conditions) along with variables affected by the discharge conditions (flocculant concentration, suspension) were studied in bench-scale experiments. The leaching tests were developed based on the case of a copper mine by Repparfjorden, northern Norway, which is planned to re-open in 2022. The experiments, which had three week duration, revealed low (<6 %) leaching of metals. Multivariate analysis showed that all variables, apart from DOC, highly influenced leaching and partitioning of at least one metal (Ba, Cr, Cu, and/or Mn). The high quantity of the planned annual discharge of mine tailings to the fjord (1-2 million tonnes) warranted estimation of the leached quantity of metals. Multivariate models, using present-day conditions in the fjord, estimated leaching of up to 124 kg Ba, 154 kg Cu and 2400 kg Mn per year during discharge of tailings. Future changes in the fjord conditions caused by climate change (decreased pH, increased temperature) was predicted by the multivariate models to increase the leaching up to 55 %, by the year 2065. The bench-scale experiments demonstrated the importance of including relevant variables (such as pH, salinity, and temperature) for metal leaching and -partitioning in leaching tests. The results showed that metal leaching during discharge is expected and will increase in the future due to the changed conditions caused by the foreseen climate change, and thereby underline the importance of monitoring metal concentrations in water during operations to determine the fate of metals in the fjord.

This workpresents a first screening of electrodialytic remediation (EDR) of eutrophic freshwater sediments contaminated by heavy metals. Sediments were collected from two heavily contaminated waterbodies north of Copenhagen, Denmark (Raadvad millpond and Bagsvaerd lake), and a less contaminated lake in an agriculturally impacted area of Jutland, Denmark (Bygholm lake). EDR at laboratory scale in batch cells (treating 100 g sediment) was experimented on all three sediments, and the two most contaminated sediments were further subject to experimental treatment in a stack setup (500/1000 g sediment) feasible for upscaling to continuous process. The results showed that all investigated elements can be extracted from freshwater sediments by EDR. The removal order was in general Zn>Cd>Pb>Cu>Ni>As>Cr. The highest removal percentages were obtained in the batch experiments for the most contaminated sediment: Zn (95%)>Cd (92%)>Pb (76%)>Cu, Ni (73%)>As (56%)>Cr (19%). Because the removal efficiency was lower for elements at low concentrations, it is uncertain whether Cd and As can be remediated to below regulatory limits, which are very low due to their high toxicity. The carbonate content was the main governing parameter, with longer treatment needed for sediments with higher carbonate content. Removal was observed from the least carbonaceous sediment (Raadvad) primarily at pH < 2, and no removal was observed at pH > 4.8. The carbonate-rich sediments (Bygholm and Bagsvaerd), on the other hand, never reached pH < 6, but nevertheless 40% Cd was removed from the Bygholm sediment, and 16% Pb was removed from the Bagsvaerd sediment. This indicates that elements in carbonate-rich sediments are partially bound in the carbonates themselves, and thus mobilized as the carbonates dissolve. However, a longer treatment time or pretreatment to dissolve the carbonate would anyhow be necessary to obtain sufficient removal from such sediments. The stack setup showed superior to the batch treatment in regards to energy consumption and remediation time, which were reduced significantly. The value of the treated sediment for amendment of agricultural soils was reduced due to depletion of P during the electrodialytic treatment. Means to recover P from the electrolyte should be developed.

Considering the vast amounts and wide variability of tailings available worldwide, means to assess the potential of tailings for cement clinker replacement based on their physical, chemical and mineralogical characteristics would be useful. This work studied the early-age properties and mechanical performance of mortar of Portland limestone cement (CEM II/A-LL) clinker in a ternary blend with partial clinker substitution by 13 metal and mineral mine tailings. The properties studied included workability, setting time, porosity and compressive strength. The effects of replacement level and mine tailing characteristics on the performance of mortar were assessed by chemometrics. The results showed that most mine tailings reduced the workability of mortar (3–19 %) and that an increased replacement level reduced the workability further. For most mine tailings, the initial setting time was identical to the reference, while they reached the final setting faster. Tailings had a variable impact on the porosity at low replacement, while porosity generally increased at a higher replacement. The compressive strength decreased with increasing replacement in most cases, and a clear negative correlation was found between compressive strength and porosity. However, five mine tailings developed up to 10 % higher strength after 28 days with 20 % supplementary composite material compared to the reference. Chemometric analyses showed that tailings with high specific surface area and silicon dioxide content influenced the mechanical properties of the mortar most positively. Conversely, larger grain sizes, high loss on ignition, calcium oxide and calcium carbonate content impacted compressive strength negatively. The analyzed characteristics do, however, not fully explain the resulting early-age and mechanical properties, thus additional investigations are needed to understand the performance in detail.

Several Greenland seaweed species have potential as foods or food ingredients, both for local consumption and export. However, knowledge regarding their content of beneficial and deleterious elements on a species specific and geographical basis is lacking. This study investigated the content of 17 elements (As, Ca, Cd, Cr, Cu, Fe, Hg, I, K, Mg, Mn, Na, Ni, P, Pb, Se and Zn) in 77 samples of ten species ( Agarum clathratum , Alaria esculenta , Ascophyllum nodosum , Fucus distichus , Fucus vesiculosus , Hedophyllum nigripes , Laminaria solidungula , Palmaria palmata , Saccharina latissima and Saccharina longicruris ). Element profiles differed between species but showed similar patterns within the same family. For five species, different thallus parts were investigated separately, and showed different element profiles. A geographic origin comparison of Fucus species indicated regional differences. The seaweeds investigated were especially good sources of macrominerals (K > Na > Ca > Mg) and trace minerals, such as Fe. Iodine contents were high, especially in macroalgae of the family Laminariaceae. None of the samples exceeded the EU maximum levels for Cd, Hg or Pb, but some exceeded the stricter French regulations, especially for Cd and I. In conclusion, these ten species are promising food items.

Oil is one of the more toxic pollutants in the environment. Due to the fragility of the Arctic environment to anthropogenic disturbances, the persistence and severity of ecological impacts from oil spills can be significant. The development of non-invasive and sustainable solutions for soil remediation is a pressing problem. The feasibility of electrokinetic technology as a remediation strategy to enhance oil removal from soil under cold climate conditions was assessed. The soil was collected in Sisimiut, Greenland from a dump site after an oil spill. A range of temperatures and different strategies for applying electric current were tested in experiments over 14 days. The soil showed a total petroleum hydrocarbon concentration of 69 500 mg kg−1, and the levels decreased between 43% and 78%. The effect of the electric field for oil removal was not verified when compared with controls. Naturally cold-adapted microorganisms seemed to have a strong influence on oil remediation under the tested conditions.

Contamination of soils with organic pollutants is an increasing global problem, so novel soil remediation techniques are urgently needed. One such technique is electrokinetic remediation, in which an electric field is applied over the soil to extract contaminants. Previous evaluations of the technique have been limited to a few specific compounds. In this study, we integrated the latest advances in high-resolution mass spectrometry (HRMS) to identify molecular fingerprints, and used the results to improve the mechanistic understanding necessary for successful remediation. A laboratory-scale 0.38 mA cm(-2) electrodialytic treatment was applied for 21 days to a contaminated soil from a firefighter training facility in Sweden. Non-target analysis allowed generic evaluation of changes in the soil organic fraction by tentatively determining the elemental composition of compounds present. The results showed that smaller oxygen-rich molecules were significantly transported to the anode by electromigration, while larger hydrogen-saturated molecules were transported to the cathode by electroosmotic flow. Wide suspect screening with >3000 per- and polyfluoroalkyl substances (PFASs) tentatively identified seven new PFASs in the test soil, including perfluoroheptanesulfonic acid (PFHpS), and PFASs with butoxy, ethoxy, ethanol, and ethylcyclohexanesulfonate functional groups.