Sewage sludge management is torn between a desire for pollution prevention and reuse of a valuable resource. Reconciling these interests in sustainable management is a challenge for researchers. This study focuses on how research on sewage sludge management practices has evolved and scrutinizes how this research is interlinked with concerns and societal issues such as contaminants, economic efficiency, and legislation. Based on published academic papers on sewage sludge management between 1971 and 2019, this study found four trends in research focused on sewage sludge management: a decreasing interest in disposal (landfilling and sea dumping), a dominant interest in land application, a growing interest in sewage sludge as product, and a stable interest in energy recovery. Research on disposal focuses on increasing sludge volumes, legislative changes, and economic challenges with an interest in waste co-treatment. Research on land application concerns nutrient use and contaminants, mainly heavy metals. Research on sewage sludge as a product focuses on the extraction of certain resources and less on use of sewage sludge specifically. Research on energy recovery of sewage sludge focuses on volume reduction rather than contaminants. Two-thirds of the papers are detailed studies aiming to improve single technologies and assessing single risks or benefits. As management of sewage sludge is multifaceted, the narrow focus resulting from detailed studies promotes some concerns while excluding others. Therefore, this study highlights potential gaps such as the combination of nutrient use and disposal and energy recovery and nutrient use. 

Gilsonite as a natural occurrence of bitumen and due to the presence of carbon in its structure is a suitable adsorbent for a wide variety of pollutants. In this research, the adsorption of cyanide from the wastewater of gold processing plants using gilsonite were investigated. In this way, the effect of particle size of gilsonite, the weight and mixing time with solution, on the amount of cyanide adsorption have been studied. In addition, in one experiment, the effect of processed gilsonite on its adsorption ability was investigated. Based on the obtained results, the maximum adsorption of 61.64% was obtained in the size range of −1+0.5 and −2+1 mm of gilsonite. With increasing adsorbent weight and mixing time, the cyanide adsorption rate were increased. On the other hand, with the processing of the gilsonite sample, the amounts of adsorption were increased considerably. This study indicated that gilsonite can be used as an isolation and absorbent in the structure and floor of the tailing dumps of mineral processing plants.

Natural resource (NR) exploitation often gives rise to conflict. While most actors intend to manage collectively used places and their NRs sustainably, they may disagree about what this entails. This article accordingly explores the origin of NR conflicts by analysing them in terms of competing pathways to sustainability. By comparing conflicts over mine establishments in three places in northern Sweden, we specifically explore the role of place-based perceptions and experiences.

The results indicate that the investigated conflicts go far beyond the question of metals and mines. The differences between pathways supporting mine establishment and those opposing it refer to fundamental ideas about human–nature relationships and sustainable development (SD). The study suggests that place-related parameters affect local interpretations of SD and mobilisation in ways that explain why resistance and conflict exist in some places but not others. A broader understanding of a particular conflict and its specific place-based trajectory may help uncover complex underlying reasons. However, our comparative analysis also demonstrates that mining conflicts in different places share certain characteristics. Consequently, a site-specific focus ought to be combined with attempts to compare, or map, conflicts at a larger scale to improve our understanding of when and how conflicts evolve. By addressing the underlying causes and origins of contestation, this study generates knowledge needed to address NR management conflicts effectively and legitimately.

Utilization of biomass and reuse of industrial by-products and their sustainable and resource-efficient development into products that are inherently non-toxic is important to reduce the use of hazardous substances in the design, manufacture and application of biomaterials. The hypothesis in this study is that spent mushroom substrate (SMS), a by-product from mushroom production, has already undergone a biological pretreatment and thus, can be used directly as a starting material for fibrillation into value-added and functional biomaterial, without the use of toxic substances. The study show that SMS can be effectively fibrillated at a very high concentration of 6.5 wt % into fibrils using an energy demand of only 1.7 kWh kg−1, compared to commercial and chemically pretreated wood pulp at 8 kWh kg−1, under same processing conditions. SMS is a promising resource for fibrillation with natural antioxidant activity and network formation ability, which are of interest to explore further in applications such as packaging. The study shows that biological pretreatment can offer lower environmental impact related to toxic substances emitted to the environment and thus contribute to reduced impacts on categories such as water organisms, human health, terrestrial organisms, and terrestrial plants compared to chemical pretreatments.

This study evaluates the operational status of twenty-six biofilter facilities across nine cities in Sweden, with respect to their functional design criteria, engineered design features (filter media composition, hydraulic conductivity, and drawdown time), and includes a visual inspection of the biofilter components (pre-treatment, in/outlet structures, filter media, and vegetation). These indicators were used to examine the performance level of each biofilter in achieving their design objectives set by the operators. Furthermore, it was investigated whether the biofilter facilities had been properly maintained to meet the objectives. Results indicate that the soil media used was consistent with respect to percentage sand, fines, and organic matter and comparable to design recommendations used by municipalities in other countries. The field-tested hydraulic conductivity for the biofilters ranged from 30 to 962 mm/h. This range of values, along with noticeable sediment accumulation within the biofilter indicate that not all the sites were operating optimally. Pre-treatment stages in poor condition with high volumes of sediment and litter accumulation were the primary causes for, and indicators of, low hydraulic conductivity rates. The ponding volume calculations revealed that at least 40 % of facilities did not have enough capacity to retain every-day and/or design rainfall due to design and/or construction flaws. These analyses raise concerns that, for a considerable number of the biofilters surveyed, water retention and flood protection identified by operators as prioritised objectives are not being met. This raises significant concerns about the functionality of biofilter in practice. Finally, some suggestions are given for tackling the design and maintenance problems discovered.

The aim of the plant pot experiment was to evaluate potential environmental impacts of combined industrial residues to be used as soil fertilisers by analysing i) element availability in fly ash and biosolids mixed with soil both individual and in combination, ii) changes in element phytoavailability in soil fertilised with these materials and iii) impact of the fertilisers on plant growth and element uptake.Plant pot experiments were carried out, using soil to which fresh residue mixtures had been added. The results showed that element availability did not correlate with plant growth in the fertilised soil with. The largest concentrations of K (3534mg/l), Mg (184mg/l), P (1.8mg/l), S (760mg/l), Cu (0.39mg/l) and Zn (0.58mg/l) in soil pore water were found in the soil mixture with biosolids and MSWI fly ashes; however plants did not grow at all in mixtures containing the latter, most likely due to the high concentration of chlorides (82g/kg in the leachate) in this ash. It is known that high salinity of soil can reduce germination by e.g. limiting water absorption by the seeds. The concentrations of As, Cd and Pb in grown plants were negligible in most of the soils and were below the instrument detection limit values.The proportions of biofuel fly ash and biosolids can be adjusted in order to balance the amount and availability of macronutrients, while the possible increase of potentially toxic elements in biomass is negligible seeing as the plant uptake of such elements was low. © 2013 Elsevier Ltd.

The aim of the study was to evaluate the impact of combined and pelletized industrial residues on availability and mobility of nutrients and potentially toxic elements in soil, plant growth and element uptake. Plant pot experiments were carried out using soil to which 2% of pelletized residue containing biosolids mixed with either municipal solid waste incineration fly ash (MFA) or biofuel fly ash (BFA) was added. The tests showed that the plant growth did not correspond to the content of available nutrients in fertilised soil. MFA application to soil resulted in elevated concentrations of P (506 mg/kg), As (2.7 mg/kg), Cd (0.8 mg/kg) and Pb (12.1 mg/kg) in soil, lower plant uptake of Al (25 mg/kg) and Ba (51 mg/kg), but higher accumulation of As (4.3 mg/kg) and Cd (0.3 mg/kg) in plants compared to the unamended soil and soil amended with BFA. On average, the biomass of the plants grown in the soil containing MFA was larger than in other soils.Considering the use of industrial residue mixtures as soil amendments or fertilizers, the amount of added elements should not exceed those taken up by plants, by this preventing the increase of soil background concentrations.

Co-management, or the joint management of the commons, is often formulated in terms of some arrangement of power sharing between the State and a community of resource users. In reality, there often are multiple local interests and multiple government agencies at play, and co-management can hardly be understood as the interaction of a unitary State and a homogeneous community. An approach focusing on the legal aspects of co-management, and emphasizing the formal structure of arrangements (how governance is configured) runs the risk of neglecting the functional side of co-management. An alternative approach is to start from the assumption that co-management is a continuous problem-solving process, rather than a fixed state, involving extensive deliberation, negotiation and joint learning within problem-solving networks. This presumption implies that co-management research should preferably focus on how different management tasks are organized and distributed concentrating on the function, rather than the structure, of the system. Such an approach has the effect of highlighting that power sharing is the result, and not the starting point, of the process. This kind of research approach might employ the steps of (1) defining the social-ecological system under focus; (2) mapping the essential management tasks and problems to be solved; (3) clarifying the participants in the problem-solving processes; (4) analyzing linkages in the system, in particular across levels of organization and across geographical space; (5) evaluating capacity-building needs for enhancing the skills and capabilities of people and institutions at various levels; and (6) prescribing ways to improve policy making and problem-solving.

Individual and organisational receptivity for change towards the use of sustainable stormwater management systems has been previously examined, but the significance of the different contexts for achieving this has been largely unexplored. This paper examines the significance of contexts associated to the actions to bring this about by proposing and evaluating an emerging framework based on two related receptivity theories: the individual or organisational approach and the contextual approach. Results from a Swedish national questionnaire with professionals in stormwater management have been used, together with a limited number of interviews to develop and understand the validity of the framework. The analysis has indicated that the respondents were professionally prepared for change (action) but not practically prepared due to inadequate supportive contexts. In response, a number of potential contexts associated to the necessary actions were identified. The framework was found to provide new insights into the influence of receptive contexts for a change in water management practice. These insights can be used by policy makers and others to better support the realization of professional openness for change and thus accelerate the process of change to sustainable stormwater practice.

The aim of this work is remediation of dairy wastewater (DWW) for biodiesel feedstock production using poly-microalgae cultures of four microalgae namely Chlorella minutissima (C. minutissima), Scenedesmus abundans (S. abundans), Nostoc muscorum (N. muscorum) and Spirulina sp. The poly-microalgae cultures were prepared as C. minutissima + N. muscorum (CN), C. minutissima + N. muscorum + Spirulina sp. (CNSS) and S. abundans + N. muscorum + Spirulina sp. (SNSS). Poly-microalgae culture CNSS cultivated on 70% DWW achieved 75.16, 61.37, 58.76, 84.48 and 84.58%, removals of biological oxygen demand (BOD), chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), and suspended solids (SS), respectively, at 12:12 h photoperiod that resulted into total biomass and lipid yield of 3.47 ± 0.07 g/L and 496.32± 0.065 mg/L. However, maximum biomass and lipid yields of 5.76 ± 0.06 and 1152.37 ± 0.065 mg/L were achieved by poly-microalgae culture CNSS cultivated on 70% DWW + 10 g/L of glucose at 18:6 h photoperiod. Fatty acid methyl ester (FAME) analysis shown presence of C14:0 (myristic acid) C16:0 (palmitic acid), C16:1 (palmitoleic acid), C18:0 (stearic acid), C18:2 (linoleic acid) and C18:3 (linolenic acid), it indicates that the lipids produced from poly-microalgae cultures are suitable for biodiesel production. Thus, poly-microalgae cultures could be more efficient than mono-microalgae cultures in the remediation of DWW and for biodiesel feedstock production.

Hierarchically porous carbon adsorbents were successfully fabricated from different biomass resources (softwood, hardwood, bamboo and cotton) by a facile two-step process, i.e. carbonization in nitrogen and thermal oxidation in air. Without involving any toxic/corrosive chemicals, large surface area of up to 890 m²/g was achieved, which is comparable to commercial activated carbon. The porous carbons with various surface area and pore size were used as adsorbents to investigate the pore size dependent adsorption phenomenon. Based on the density functional theory, effective (E-SSA) and ineffective surface area (InE-SSA) was calculated considering the geometry of used probing adsorbate. It was demonstrated that the adsorption capacity strongly depends on E-SSA instead of total surface area. Moreover, a regression model was developed to quantify the adsorption capacities contributed from E-SSA and InE-SSA, respectively. The applicability of this model has been verified by satisfactory prediction results on porous carbons prepared in this work as well as commercial activated carbon. Revealing the pore size dependent adsorption behavior in these biomass derived porous carbon adsorbents will help to design more effective materials (either from biomass or other carbon resources) targeting to specific adsorption applications.

The depletion of resource reserves will cause stagnation of socio-economic development in resource-based cities. The formation of new sources of economic growth in resource-depleted cities can profoundly change the structure of human activities and affect the environment. The Chinese government has established a list of resource-depleted cities in three batches since 2008 to support these cities in finding new sources of economic growth. The article analyzes the impact of the regeneration process of resource-based cities on ecosystem quality. The paper constructs an inter-city panel dataset covering 281 cities from 2003 to 2018. The article valued the habitat quality of Chinese cities. Habitat quality index and normalized vegetation index were used to measure the long-term and short-term ecological impacts of economic recovery in resource-based cities. Using a difference-in-difference technique, the results show that the central government's economic support for resource-based cities significantly improves the condition of urban ecosystems. However, the long-term ecological effects are still smaller than the short-term changes in ecosystems. The transmission path of support policies affecting the ecological quality of cities depends on the shift in industrial structure and economic scale at the provincial level. In addition, urban-rural differences, regional distribution, and resource endowment also significantly affect the ecological effects of supportive policies.

Swales are the oldest and most common stormwater control measure for conveying and treating roadway runoff worldwide. Swales are also gaining popularity as part of stormwater treatment trains and as crucial elements in green infrastructure to build more resilient cities. To achieve higher pollutant reductions, swale alternatives with engineered media (bioswales) and wetland conditions (wet swales) are being tested. However, the available swale design guidance is primarily focused on hydraulic conveyance, overlooking their function as an important water quality treatment tool. The objective of this article is to provide science-based swale design guidance for treating targeted pollutants in stormwater runoff. This guidance is underpinned by a literature review.

The results of this review suggest that well-maintained grass swales with check dams or infiltration swales are the best options for runoff volume reduction and removal of sediment and heavy metals. For nitrogen removal, wet swales are the most effective swale alternative. Bioswales are best for phosphorus and bacteria removal; both wet swales and bioswales can also treat heavy metals. Selection of a swale type depends on the site constraints, local climate, and available funding for design, construction, and operation. Appropriate siting, pre-design site investigations, and consideration of future maintenance during design are critical to successful long-term swale performance. Swale design recommendations based on a synthesis of the available research are provided, but actual design standards should be developed using local empirical data. Future research is necessary to identify optimal design parameters for all swale types, especially for wet swales.

The study deals with the pyrolysis of sewage sludge to produce eco-friendly and sustainable fuels along with value-added biochar products. The experiments were conducted in a fixed-bed cylindrical glass reactor in the temperature range of 250–700 °C and achieved the product yield of 22.4 wt% bio-oil, 18.9 wt % pyrolysis gases, and 58.7 wt% biochar at 500 °C optimum temperature. The chemical composition of bio-oil was investigated by gas chromatograph-mass spectroscopy and fourier transformation infrared techniques. The ASTM standard procedures were used to assess the fuel qualities of bio-oil, and they were found to be satisfactory. Bio-oil has a greater H/C ratio (3.49) and a lower O/C ratio (1.10), indicating that it is suitable for engine use. The gas chromatographic analysis of pyrolysis gases confirmed the presence of 41.16 wt % combustible gases, making it suitable for use in spark-ignition engines. X-ray fluorescence analysis of biochar showed that it had a good amount of carbon, nitrogen, phosphorus, and potassium along with some micro-and macro-nutrient which proves its potential to utilize as organic manure in the agriculture sector. In addition, the data obtained from the TGA analysis during the pyrolysis of sewage sludge was applied to calculate kinetic parameters via the Coats-Redfern method.

The fly ash (FA) from the combustion of heavy oil in power stations is characterized by fine particles containing toxic metals. The sample utilized in this study was gathered from the dust precipitators of seven heavy-oil-consuming Iranian power plants. Substantial quantities of heavy metals, particularly vanadium, iron, and nickel, have been detected in the sample, indicating both its potential utility and hazard to the soil and groundwater. The harmful consequences of FA disposal on the environment have led to the adoption of recycling as a treatment approach in this study. The valorization of FA was investigated by producing nickel ferrite (NiFe2O4) and vanadium pentoxide (V2O5) through a novel approach using a combination of pyro-hydrometallurgical processes, which resulted in proposing a recycling closed-loop flowsheet. Roasting was first practiced to form NiFe2O4 by reacting the nickel and iron content of the FA. The NiFe2O4 showed a low dissolution against inorganic acids (H2SO4, HCl, and HNO3). The vanadium content of the FA showed a remarkable recovery in H2SO4 (91%) and HCl (95.6%), while the dissolution of Ni was limited to 16.85% and 17.5%, respectively. The produced NiFe2O4 acted well in response to the magnetic field, and its purity was further increased to 95–96% through a two-stage process consisting of grinding and magnetic separation. The nano-sized spherical NiFe2O4 with saturation magnetization of 34.66 and 30.82 emu. g−1 was obtained from H2SO4 and HCl residues, respectively. The dissolved vanadium was recovered as V2O5 via oxidation-precipitation in sulfate media and oxidation-ammonium precipitation in chloride solution. The purity of V2O5 in sulfate and chloride media was 93% and 98.5%, respectively. Finally, a life cycle assessment (LCA) study was performed on the suggested methods to track the ecological effects of extracting V and Ni from oil combustion FA. According to the performed LCA, H2SO4 was determined as the proper leaching reagent considering the environmental and technical aspects.

This study was conducted to investigate the feasibility of microalgal biomass production and nutrient removal from recirculating aquaculture systems (RAS) water (RASW) with low phosphate concentration. For this purpose, Nannochloropsis oculata, Pavlova gyrans, Tetraselmis suecica, Phaeodactylum tricornutum, and their consortium were cultivated in RASW and RASW supplemented with vitamins (+V). Among them, N. oculata showed the maximum biomass production of 0.4 g/L in RASW. Vitamins supplementation significantly increased the growth of T. suecica from 0.16 g/L in RASW to 0.33 g/L in RASW + V. Additionally, T. suecica showed the highest nitrate (NO3–N) removal efficiency of 80.88 ± 2.08 % in RASW and 83.82 ± 2.08 % in RASW + V. Accordingly, T. suecica was selected for scaling up study of microalgal cultivation in RASW and RASW supplemented with nitrate (RASW + N) in 4-L airlift photobioreactors. Nitrate supplementation enhanced the growth of T. suecica up to 2.2-fold (day 15). The fatty acid nutritional indices in T. suecica cultivated in RASW and RASW + N showed optimal polyunsaturated fatty acids (PUFAs)/saturated fatty acid (SFAs), omega-6 fatty acid (n-6)/omega-3 fatty acid (n-3), indices of atherogenicity (IA), and thrombogenicity (IT)). Overall, the findings of this study revealed that despite low phosphate concentration, marine microalgae can grow in RASW and relatively reduce the concentration of nitrate. Furthermore, the microalgal biomass cultivated in RASW consisting of pigments and optimal fatty acid nutritional profile can be used as fish feed, thus contributing to a circular bioeconomy.

Deliberative processes are increasingly advocated as means to handle intractable natural resource management (NRM) conflicts. Research shows that disputing actors can deliberate and achieve higher degrees of mutual understanding and working agreements under ideal conditions, but the transferability of these findings to real-world intractable NRM conflicts can be questioned. This paper explores the possibilities of designing and realizing deliberation and its expected outcomes in real-world NRM conflicts. We used recommended design principles to set up deliberative processes in two intractable mining conflicts involving indigenous peoples in Northern Sweden and assessed the actors’ communication and outcomes using frame analysis.

The results show that the recommended design principles are hard, but not impossible, to fully implement in intractable NRM conflicts. Both conflicts proved difficult to deliberate and resolve in the sense of reaching agreements. However, the findings suggest that deliberation, as well as meta-consensus, or structured disagreement, is possible to achieve in settings with favorable conditions, e.g. good and established inter-group relations prior to the conflict. In the absence of these conditions, where relations were hostile and shaped by historical and institutional injustices, deliberation was not achieved. In both cases, polarization among the participants remained, or increased, in spite of the deliberative activities. The study highlights the importance of understanding deliberation as embedded in place specific historical and institutional contexts which shape both process and outcomes in powerful ways. More efforts should focus on alternative, or complementary, ways to handle intractable NRM conflicts, including how contested experiences of history, institutions and Indigenous rights can be addressed.

An in situ method for spreading iron amendments to arsenic (As)-contaminated soil has been investigated in the laboratory and field. This study tested the distribution of Fe from corroding electrodes through soil using a low-voltage direct current in a laboratory setting and validated the method in the field for As immobilisation in contaminated soil. Laboratory tests revealed that the corrosion of Fe electrodes in soil occurred in a way similar to that during the Fe electrocoagulation in water, which decreased the As concentrations in flow-through water from 150 μg L−1 to undetectable levels. Method validation over one year in the field using electric current pulses with reversing polarity revealed a decrease in As concentration in groundwater by 72–97% in five of the six groundwater wells within the experimental area. This method of introducing Fe amendments to soil can reduce the need for soil excavation upon chemical immobilisation of contaminants in soil.

Thermal treatment, if properly performed, is an effective way of destroying organic compounds in contaminated soil, while impact on co-present inorganic contaminants varies depending on the element. Leaching of trace elements in thermally treated soil can be altered by co-combusting different types of materials. This study aimed at assessing changes in mobility of As, Cr and Cu in thermally treated soil as affected by addition of industrial by-products prior to soil combustion. Contaminated soil was mixed with either waste of gypsum boards, a steel processing residue (Fe₃O₄), fly ash from wood and coal combustion or a steel abrasive (96.5% Fe⁰). The mixes and unamended soil were thermally treated at 800 °C and divided into a fine fraction <0.125 mm and a coarse fraction >0.125 mm to simulate particle separation occurring in thermal treatment plants. The impact of the treatment on element behaviour was assessed by a batch leaching test, X-ray absorption spectroscopy and dispersive X-ray spectrometry. The results suggest that thermal treatment is highly unfavourable for As contaminated soils as it increased both the As leaching in the fine particle size fraction and the mass of the fines (up to 92%). Soil amendment with Fe-containing compounds prior to the thermal treatment reduced As leaching to the levels acceptable for hazardous waste landfills, but only in the coarse fraction, which does not justify the usefulness of such treatment. Among the amendments used, gypsum most effectively reduced leaching of Cr and Cu in thermally treated soil and could be recommended for soils that do not contain As. Fly ash was the least effective amendment as it increased leaching of both Cr and As in majority of samples.

Landfills generate emissions in the form of gas and leachate. The emissions are often measured within monitoring programmes. It is likely that the requirements of such monitoring programmes can be extended in the future, particularly in light of the increased interest in specific organic substances. Multivariate data analyses (MVDA) have been used to evaluate the possibility of predicting the content of specific organic substances from more common analyses. The results indicate that this is possible for a specific leachate. MVDA can also be used to reduce the number of analyses performed within existing monitoring programmes while retaining information about all the variables formerly included in the programmes.

To study effects of plant species selection on total and dissolved metal treatment performance of bioretention systems (BRS), 12 sets of columns were prepared, each planted with one of 12 species that are either widely used in BRS or have potentially important traits for metal removal (ability to hyperaccumulate metals, C4 photosynthesis, or ability to form mycorrhiza). Artificial stormwater was applied to half of the columns during all of a 31-week test period, while treatment of the others included a 5-week long dry period to test interactive effects of drying and plant traits on BRS metal treatment in more realistic alternating wet and dry conditions. Concentrations of metals (dissolved and total) in the effluent significantly differed between most columns with different plants, and the differences in concentrations of dissolved metals after the dry period were particularly important. Mean dissolved Cd concentrations exceeded Swedish reference values in effluents from BRS with two of the plant species, while mean dissolved Zn concentrations exceeded them in effluents from BRS with three of the species (and non-vegetated controls). Dissolved Cu leaching was observed in effluents from BRS with five of the plant species after the dry period, and mean concentrations exceeded Swedish reference values in effluents from all the BRS (including the constantly watered systems). Some support in terms of metal concentrations in shoots and shoot/soil ratios was obtained for using hyperaccumulators in BRS to remove metals from filter material. For example, Armeria maritima (a hyperaccumulator with the lowest shoot biomass) and Miscanthus sinsenis (a C4 plant with the highest biomass production) took up similar amounts of metals despite large differences in biomass. However, no significant correlations between effluent metal concentrations and plants’ metal uptake were found, possibly because of the short duration of the experiment. The results indicate that root biomass affected effluent metal concentrations more strongly. Root biomass was often positively correlated with total and (particularly) dissolved effluent metal concentrations. Further experiments with different soil metal concentrations, organic matter analyses and stronger focus on root characteristics are recommended, including additional tests of effects of hyperaccumulators and mycorrhiza on metal treatment and phytoextraction.

The leaching behaviour of a road construction with fayalitic copper slag, recycled concrete and crushed rock as sub-base materials was monitored over ten years. All studied materials used in the road construction, including crushed rock, contained concentrations of several elements exceeding the guideline values recommended by the Swedish EPA for total element concentrations for waste materials used in constructions. Despite that, leaching from the road construction under field conditions in general was relatively low. The leachates from the recycled materials contained higher concentrations of several constituents than the leachates from the reference section with crushed rock. The leaching of the elements of interest (Cr, Mo, Ni, Zn) reached peak concentrations during the second and fourth (Cu) years and decreased over the observation period to levels below the Swedish recommended values. Carbonation of the concrete aggregates caused a substantial but short-term increase in the leaching of oxyanions such as chromate. The environmental risks related to element leaching are highest at the beginning of the road life. Ageing of materials or pre-treatment through leaching is needed prior to their use in construction to avoid peak concentrations. Also, the design of road constructions should be adjusted so that recycled materials are covered with low-permeability covers, which would minimize the exposure to atmospheric precipitation and weathering.

Urban runoff is a diffuse source of pollution contributing to the poor ecological and chemical status of surface waters. Whilst the EU Priority Hazardous Substances Directive now identifies environmental quality standards for selected metals in relation to the bioavailable metal fraction the relationship between analytically determined metal size fractions transported by urban runoff and the often variably defined concept of bioavailability has not been thoroughly evaluated. This paper provides a review of the terminology used within urban runoff studies to characterise metal fractions and behaviour. Measured dissolved and truly dissolved (determined by ultrafiltration; <3000 molecular weight cutoff) Cu, Ni, and Zn concentrations are also compared to the bioavailable metal fraction (as predicted using Bio-met, a simplified biotic ligand model) in snowmelt and rainfall derived runoff samples from three urban catchments. The study shows that predicted bioavailable concentrations were significantly lower than truly dissolved concentrations for all metals and discusses current bioavailability modelling parameters in relation to rainfall and snowmelt runoff data sets. Statistical analysis of relationships between field and predicted bioavailable data sets indicate that the bioavailable fractions originate from both colloidal and truly dissolved fractions.

The aim of this study was to determine element mobilization and accumulation in mill tailings under alkaline conditions. The tailings were covered with 50 cm of fly ash, and above a sludge layer. The tailings were geochemically and mineralogically investigated. Sulfides, such as pyrrhotite, sphalerite and galena along with gangue minerals such as dolomite, calcite, micas, chlorite, epidote, Mn-pyroxene and rhodonite were identified in the unoxidized tailings. The dissolution of the fly ash layer resulted in a high pH (close to 12) in the underlying tailings. This, together with the presence of organic matter, increased the weathering of the tailings and mobilization of elements in the uppermost 47 cm of the tailings. All primary minerals were depleted, except quartz and feldspar which were covered by blurry secondary carbonates. Sulfide-associated elements such as Cd, Fe, Pb, S and Zn and silicate-associated elements such as Fe, Mg and Mn were released from the depletion zone and accumulated deeper down in the tailings where the pH decreased to circum-neutral. Sequential extraction suggests that Cd, Cu, Fe, Pb, S and Zn were retained deeper down in the tailings and were mainly associated with the sulfide phase. Calcium, Cr, K and Ni released from the ash layer were accumulated in the uppermost depletion zone of the tailings

The aim of this study is to examine the transformative capacity of top-down imposed collaborative institutions on participants’ beliefs and coordination patterns. First, do collaborative arenas enhance learning in terms of belief change and belief convergence among participating actors? Second, what types of beliefs are changed and, third, how are changes in beliefs reflected in the formation of coalitions? To answer these questions, a longitudinal study encompassing three collaborative decision-making arenas in the highly adversarial system for wildlife management in Sweden is performed. The empirical analysis indicates both stability and change within the new management system that confirms, as well as challenges, the theoretical assumptions guiding the analysis. While beliefs overall are rather stable, we note, surprisingly, how some participants’ more normatively oriented policy core beliefs have been slightly modified over time. A more expected result was that these adjustments in normative policy core beliefs were accompanied by a reformed coalition structure within the studied decision-making arenas. The study contributes to our understandings of policy beliefs and coalitions in conflicted policy areas; it underlines the mixed results of collaborative institutions found in previous research; yet, lends a modest support in favor of the transformative capacity of collaborative institutions.

In the context of increasing urbanization and global warming, there is a growing interest in the implementation of green infrastructure (GI) across different climates and regions. Identifying an appropriate GI design criteria is essential to ensure that the design is tailored to satisfy local environmental requirements. This article aims to compare the hydrological performance of GI facilities in eleven Swedish cities by isolating the effect of climatic conditions using an identical GI design configuration. Long-term simulations based on 23-years of meteorological time-series were used as inputs for the Storm Water Management Model (SWMM) with Low Impact Development (LID) controls representing two types of facilities: a biofilter cell (BC) and a green roof. (GR). Large differences in potential annual and seasonal runoff retention were found between locations, driven mainly by the extent of winter/spring season, and the distribution of precipitation patterns (for BCs) and the sequence of rainy days-dry periods and evapotranspiration rates (for GRs). Winter/spring and summer demonstrated the highest/lowest differences between the seasons, results that suggest that implications for design might be aligned to the spatio-temporal distribution of precipitation patterns, and runoff regimes generated by snowmelt and rain-on-snow events, in locations where snowmelt represent high portion of runoff generation.

Ever since the advent of major sewer construction in the 1850s, the issue of increased solids deposition in sewers due to changes in domestic wastewater inputs has been frequently debated. Three recent changes considered here are the introduction of kitchen sink food waste disposers (FWDs); rising levels of inputs of fat, oil and grease (FOG); and the installation of low-flush toilets (LFTs). In this review these changes have been examined with regard to potential solids depositional impacts on sewer systems and the managerial implications. The review indicates that each of the changes has the potential to cause an increase in solids deposition in sewers and this is likely to be more pronounced for the upstream reaches of networks that serve fewer households than the downstream parts and for specific sewer features such as sags. The review has highlighted the importance of educational campaigns directed to the public to mitigate deposition as many of the observed problems have been linked to domestic behaviour in regard to FOGs, FWDs and toilet flushing. A standardized monitoring procedure of repeat sewer blockage locations can also be a means to identify depositional hot-spots. Interactions between the various changes in inputs in the studies reviewed here indicated an increased potential for blockage formation, but this would need to be further substantiated. As the precise nature of these changes in inputs have been found to be variable, depending on lifestyles and type of installation, the additional problems that may arise pose particular challenges to sewer operators and managers because of the difficulty in generalizing the nature of the changes, particularly where retrofitting projects in households are being considered. The three types of changes to inputs reviewed here highlight the need to consider whether or not more or less solid waste from households should be diverted into sewers.

Runoff from building and structure surfaces may contribute to the pollution of urban stormwater and, thereby, to the degradation of the receiving water quality. Various micropollutants have been found in surface runoff from buildings in the urban environment, including metals and organic micropollutants. Effective methods for identification of such pollutants and their sources are the prerequisites for the development of control measures. In this paper, three different methods for the identification of building surface materials acting as sources of metals (Cd, Cr, Cu, Ni, Pb and Zn), nonylphenols and phthalates are presented: (i) screening of the material composition, (ii) laboratory leaching experiments with synthetic rainwater, and (iii) open-air pilot testing of material panels exposed to actual rainfall and runoff. These three methods cover a wide span of experimental aspects, including, e.g., size of material samples, resource demands, and control of influential factors. Nine materials commonly used on building and structure surfaces in the urban environment were tested: metal sheets of zinc, copper, galvanised steel, coated corrugated steel and stainless steel; and, four different roofing membranes of bitumen as well as polyvinyl chloride (PVC). The experimental results indicated that all three methods were meritorious in providing some information contributing to the identification of pollutant sources. The screening of material composition for targeted pollutants is relatively quick and inexpensive, but may fail to identify minor sources of pollutants, or may identify the substances present in the material, but not released in contact with water. Laboratory leaching was generally effective in identifying sources of substances present in surface runoff, but was unsuitable for estimating the magnitude of actual concentrations in building runoff. Open-air pilot studies of material samples (exposed area = 2 m2) were thought to provide the results corresponding well to concentrations in runoff from actual building surfaces, but required relatively large financial and labour resources. Thus, the choice of the method for pollutant identification should be based on study objectives, and some benefits may be achieved using more than one method in an integrated manner; e.g., composition screening and lab or open-air leaching of targeted materials.

In 2009, a low-volume gravel road in Sweden was stabilised using fly ash from a local paper mill. The objective was to examine whether fly ash could be used to enhance the stability of the road and how the nearby environment would be affected. The technical and environmental properties of the road have been monitored for two, six, and eleven years. Because the construction costs are higher for ash upgrading than for conventional upgrading, knowing for how long the improved properties will remain is relevant. Strength development was studied using a falling weight deflectometer and compressive strength tests. Environmental properties were studied by chemical analysis of road samples, soil, soil pore water, and vegetation. The results showed that the ash sections had higher stiffness than the reference sections. Leaching tests of road samples showed that the mobility of potassium, sodium, chloride, and sulfate decreased with time. Trace element concentrations in soil samples, except barium, were below the Swedish guideline values for sensitive land use. Chromium, lead, and copper were as high or even higher along the reference section than along the ash section. After 11 years, the pH closest to the ash section was slightly enhanced. Concentrations of zinc and cadmium in the soil pore water were the lowest closest to the ash road, although the total concentrations in the soil were at their highest at the same distance. No toxic levels of trace elements were found in the vegetation close to the road, although a clear difference was observed between plants from the ash section and the reference section, using multivariate data analysis. The positive effects on the geotechnical road properties from ash stabilisation remained after 11 years. The environmental impacts on nearby soil and vegetation can be considered low and acceptable. This study demonstrates that the use of biofuel fly ash in infrastructure projects can contribute to the circular economy and effective use of resources because the demand for pristine materials will be reduced.

The quest for steady primary supplies of critical raw materials (CRMs) creates significant waste, which is inevitably generated at each phase of mining and mineral processing. Waste from extraction, separation and refinement of non-renewable natural resources is accumulated globally and creates not only environmental hazards but also economic possibilities. Mine waste management is an expensive and prolonged task but unavoidable. Mine tailings, especially historical ones, can contain economically feasible resources, and given the right condition, such tailings could be reutilised through a waste valorisation concept. A prominent example are the Witwatersrand gold mine tailings in South Africa, which have been reused in small-scale projects. Tailing reutilisation is only possible if a sound classification, sampling and resource modelling framework is established to thoroughly and accurately profile the economic, environmental, health and geometallurgical aspects. Our study on valorisation of mine waste is presented in two parts: Here, in Part I, we focus on the essential components of a mine waste valorisation framework that includes the characterization and development of a systematic sampling framework for consolidated mineralised tailings. The development of a mine waste valorisation framework will hopefully enable worldwide reduction and reutilisation of mine waste.

Mine waste can create long-term and occasionally catastrophic environmental degradation. Due diligence of mine waste in the form of monitoring and maintenance requires a constant supply of societal resources. Furthermore, mine waste is unlikely to disappear with current mining methods and instead, it is more likely to accumulate at a faster rate due to decreasing primary ore grades and increasing societal demands. However, mine waste can be a societal asset, as it can offer an alternative source of partly critical raw materials (CRMs) that can augment primary sources and provide an opportunity to mitigate supply-risk while ensuring sustainability and easing geopolitical tensions. Cobalt is a critical raw material that is largely a by-product of mining of copper, nickel and platinum-group element ores. It is an element that the renewable energy and high-tech sectors critically depend on and for which no reasonable substitutes currently exist. The majority of the global cobalt production stems from the Central African Copperbelt. Published cobalt production figures for the Central African Copperbelt were used to evaluate cobalt tailings from the Central African Copperbelt. As part of a waste valorisation framework that focuses on primarily on the technical aspects of mine waste valorisation, this study assesses the application of key geostatistical methods, such as kriging and conditional simulation, followed by uniform conditioning, to evaluate the resource potential in a hypothetical copper-cobalt tailing deposit from the Central African Copperbelt. The results indicate that methods such as traditional algorithmic kriging, sequential Gaussian simulation and uniform conditioning are highly effective tools in resource modelling of mine waste. The resource assessment framework component developed in this study makes it possible to systematically characterise, profile and model any mine waste storage facility and thus supplements other framework components discussed in an accompanying paper to maximise mine waste utilization.

Even in separate sewer systems, wastewater may find its way into the receiving waters through stormwater sewers. The main reasons for this are cross-connections, illicit connections, overflows and leakages through broken sewers. Such discharges may affect receiving water quality and increase risks to public health and aquatic organisms. Detecting wastewater contamination and locating its points of ingress into storm sewer systems can be a challenging task, which should be addressed using proper methods and indicator parameters. A number of detection methods have already been proposed in this area, yet there is a lack of a general overview of such methods. This literature review summarizes and evaluates the methods used for detecting wastewater in stormwater, including those recently developed. The advantages, weaknesses and limitations of individual methods are discussed. It is concluded that while no single method can as yet produce results in a precise, fast and inexpensive way, the use of human waste specific chemical and microbiological markers, and their innovative sampling, offer the way forward. Guidance for selecting the most effective combinations of detection methods, under specific conditions, is also provided.

Bioretention systems for urban drainage are one type of blue-green infrastructure that have gained more attention in recent decades. There are numerous design options for these systems, including various construction components, filter material mixtures, and plants. However, the research focus on the impacts of these many design options has mainly been technical, i.e., how different bioretention designs affect runoff pollution treatment and hydraulic control. Knowledge of the effects of various design elements on other sustainability criteria, such as economic, social, and environmental aspects, needs to be developed. This research aimed to evaluate and compare various design elements and bioretention types to gain a better understanding of the relative sustainability of various bioretention systems. This was accomplished by identifying relevant criteria and sub-criteria, covering social, economic, and technical-environmental indicators, in a multicriteria analysis. To evaluate the sustainability performance of various bioretention designs, 12 sub-criteria were allotted −100 to 100 points in a scoring process. The main finding was that while design features had a major impact on bioretention performance, no single design configuration excelled in all criteria. High scores in the social criteria were correlated with the use of trees and smaller volumes of pumice in the filter material mixture. In the economic criteria, extensive use of concrete and a complex mixture of filter material increased the costs. The system with a water-saturated zone and a variety of plant species outperformed the other systems in the technical-environmental criteria. The results can be utilized as a reference to assess design configurations that best satisfy specific needs for each unique bioretention implementation.

Green walls in urban environments can be both an aesthetic feature and be of practical use in greywater treatment. This study evaluates the effect of different loading rates (4.5 l/d, 9 l/d, and 18 l/d) on the efficiency of treating actual greywater from a city district in a pilot-scale green wall with five different filter materials as substrates (biochar, pumice, hemp fiber, spent coffee grounds (SCG), and composted fiber soil (CFS)). Three cool climate plant species, Carex nigra, Juncus compressus, and Myosotis scorpioides, were chosen for the green wall. The following parameters were evaluated: biological oxygen demand (BOD), fractions of organic carbon, nutrients, indicator bacteria, surfactants, and salt. Three of the five materials investigated – biochar, pumice, and CFS - showed promising treatment efficiencies. The respective overall reduction efficiencies of BOD, total nitrogen (TN) and total phosphorus (TP) were 99%, 75%, and 57% for biochar; 96%, 58%, and 61% for pumice; and 99%, 82% and 85% for CFS. BOD was stable in the biochar filter material with effluent concentrations of 2 mg/l across all investigated loading rates. However, higher loading rates had a significantly negative effect on hemp and pumice for BOD. Interestingly, the highest loading rate (18 l/d) flowing over pumice removed the highest levels of TN (80%) and TP (86%). Biochar was the most effective material in removing indicator bacteria, with a 2.2–4.0 Log10 reduction for E. coli and enterococci. SCG was the least efficient material, giving a higher BOD in the effluent than in the influent. Therefore, this study presents the potential of natural and waste-derived filter materials to treat greywater effectively and the results can contribute to the future development of nature-based greywater treatment and management practices in urban areas.

Eight on-site greywater treatment facilities of four different types (A, B, C and D) were investigated. Three were commercially available package plants (A–C) and one was a conventional sand filter (D). The treatment unit of Type A consisted of a geotextile-fitted trickling filter and a sand filter bottom layer, the Type B consisted of packs of fibrous mineral wool filter materials, and the Type C consisted of a fine-meshed plastic filter. The treatment systems were assessed in terms of their removal efficiency for organic matter (e.g. BOD, COD, TOC), nutrients (nitrogen and phosphorus), surfactants, indicator bacteria (E. coli and enterococci) as well as microplastics. Systems A and D effectively reduced organic matter by >96% BOD, >94% COD and >90% TOC. Their effluent BOD was <29 mg/l. The BOD reduction in the treatment facilities of types B and C was in the range of 70–95%. Removal of anionic surfactants was >90% with effluent concentration <1 mg/l in all facilities. In general, the treatment systems were ineffective in removing E. coli and enterococci; the most efficient was the sand filter (type D), achieving 1.4–3.8 log10 for E. coli and 2.3–3.3 log10 for enterococci. Due to the high E. coli in the effluents, all the on-site systems were classified as Poor (score: 0–44) according to the water quality index (WQI) assessment. In two of the studied facilities, nine microplastic polymers were targeted (i.e. PVC, PS, PET, PE, PC, NG, PMMA, PP and PA6) and analyzed using the thermal extraction desorption gas chromatography-mass spectrometry (TED-GCMS) technique. PVC, PS, PET and PA6 were commonly detected in the influent and effluent. The effluent quality from type A and D systems was found to comply with the European Commission’s guideline for the reuse of reclaimed water except for the indicator bacteria concentration.

How do different multi-level governance models influence the adaptive capacity of environmental management? This paper examines the connection between different types of governance models, distinguished by diverse institutional features, and elements of adaptive capacity. The task is undertaken through a comparative study of two differently organized management systems within the same national context: Swedish water and large carnivore management. The systems’ governance models are defined through an institutional analysis of polycentric features, logics of design and knowledge arrangements. Assessments of adaptive capacity are based on survey data describing the involved actors' perceptions of the knowledge base, use of an experimental approach and the presence of learning. The empirical results suggest that institutional features influence some, but not all, elements of adaptive capacity. The results lend support to the idea that polycentric governance models, based on an ecological rationale, sustain participation in knowledge mobilization, support the use of an experimental approach and promote learning to a larger extent than more centralized and hierarchical governance models do; while there is no connection between governance model and the perceived reliability of knowledge base. The study contributes to environmental governance research, policy and practice by evaluating the adaptive capacity of current water and wildlife management systems in Sweden and by increasing our knowledge about how different governance models influence the adaptive capacity in environmental management.

In this paper, we assert that an important element is largely missing in much of the current environmental policy literature regarding different management ideals: street-level bureaucrats (i.e., the practicing and, typically, anonymous civil servants at the very end of the environmental policy chain). Thus, we aim to enhance a deeper understanding of the role that street-level bureaucrats play within different management ideals, and through this discussion, we indicate how they affect the functionality of governing structures and processes. We do so by interviewing street-level bureaucrats carrying out their role in different management settings, enabling evaluations of the degree to which their practices correspond with the ideals expressed in the literature and in official directives. We find a rather poor match between these ideals on one hand and the way street-level bureaucrats actually perceive that they are internally steered and how they carry out their commissions on the other hand.

Contemporary processes of environmental policymaking in general span over several territorial tiers. This also holds for the EU Water Framework Directive system of environmental quality standards (EQS), which are part of a complex multi-level institutional landscape, embracing both EU, national and sub-national level. Recent evaluations show that many EU member states, including Sweden, have not reached the ecological goals for water in 2015. Departing from theories on policy coherence and multi-level governance, this paper therefore analyses Swedish water governance as a case to further our understanding of policy implementation in complex governance structures: how does policy coherence (or the lack thereof) affect policy implementation in complex governance structures? To answer this question, the paper maps out the formal structure of the water governance system, focusing on power directions within the system, analyses policy coherence in Swedish water governance through mapping out policy conflicts between the EQS for water and other goals/regulations and explore how they are handled by national and sub-national water bureaucrats. The study concludes that without clear central guidance, ‘good ecological status’ for Swedish water will be difficult to achieve since incoherent policies makes policy implementation inefficient due to constant power struggles between different authorities, and since environmental goals are often overridden by economic and other societal goals. Further research is needed in order to explore if similar policy conflicts between water quality and other objectives occur in other EU member states and how bureaucrats handle such conflicts in different institutional settings. This study of the Swedish case indicates that the role of the state as a navigator and rudder-holder is important in order to improve policy implementation in complex governance structures – otherwise; bureaucrats risk being lost in an incoherent archipelago of ecological, social and economic goals.

The aim of this study was to investigate the stability of As, Cr and Cu in contaminated soil treated with air pollution control residues under landfill conditions. The influence of landfill gas and temperature on the release of trace elements from stabilized soil was simulated using a diffusion test. The air pollution control residues immobilized As through the precipitation of Ca–As minerals (calcium arsenate (Ca5H2(AsO4)3 × 5H2O), weilite (CaAsO4) and johnbaumite (Ca5(AsO4)3(OH)), incorporation of As into ettringite (Ca6Al2(SO4)3(OH)12 × 26H2O) and adsorption by calcite (CaCO3). The air pollution control residues generally showed a high resistance to pH reduction, indicating high buffer capacity and stability of immobilized As in a landfill over time. Generation of heat in a landfill might increase the release of trace elements. The release of As from stabilized soil was diffusion-controlled at 60 °C, while surface wash-off, dissolution, and depletion prevailed at 20 °C. The air pollution control residues from the incineration of municipal solid waste immobilized Cr, indicating its stability in a landfill. The treatment of soil with air pollution control residues was not effective in immobilization of Cu. Contaminated soils treated with air pollution control residues will probably have a low impact on overall leachate quality from a landfill.

Electrochemical degradation using boron-doped diamond (BDD) electrodes has been proven to be a promising technique for the treatment of water contaminated with per- and poly-fluoroalkyl substances (PFAS). Various studies have demonstrated that the extent of PFAS degradation is influenced by the composition of samples and electrochemical conditions. This study evaluated the significance of several factors, such as the current density, initial concentration of PFAS, concentration of electrolyte, treatment time, and their interactions on the degradation of PFAS. A 2⁴ factorial design was applied to determine the effects of the investigated factors on the degradation of perfluorooctanoic acid (PFOA) and generation of fluoride in spiked water. The best-performing conditions were then applied to the degradation of PFAS in wastewater samples. The results revealed that current density and time were the most important factors for PFOA degradation. In contrast, a high initial concentration of electrolyte had no significant impact on the degradation of PFOA, whereas it decreased the generation of F⁻. The experimental design model indicated that the treatment of spiked water under a current density higher than 14 mA cm⁻² for 3–4 h could degrade PFOA with an efficiency of up to 100% and generate an F⁻ fraction of approximately 40–50%. The observed high PFOA degradation and a low concentration of PFAS degradation products indicated that the mineralization of PFOA was effective. Under the obtained best conditions, the degradation of PFOA in wastewater samples was 44–70%. The degradation efficiency for other PFAS in these samples was 65–80% for perfluorooctane sulfonic acid (PFOS) and 42–52% for 6–2 fluorotelomer sulfonate (6-2 FTSA). The presence of high total organic carbon (TOC) and chloride contents was found to be an important factor affecting the efficiency of PFAS electrochemical degradation in wastewater samples. The current study indicates that the tested method can effectively degrade PFAS in both water and wastewater and suggests that increasing the treatment time is needed to account for the presence of other oxidizable matrices.

Package plants (PP) are implemented around the world to provide on-site sanitation in areas not connected to a sewage network. The efficiency of PP has not been comprehensively studied at full scale, and the limited number of available studies have shown that their performance varies greatly. Their performance under cold climate conditions and the occurrence of micropollutants in PP effluents have not been sufficiently explored. PP are exposed to environmental factors such as low temperature, especially in cold regions with low winter temperatures and deep frost penetration, that can adversely influence the biochemical processes. The aim of this study was to investigate the treatment efficiency and possible effects of cold temperatures on PP performance, with focus on traditional contaminants (organics, solids, nutrients and indicator bacteria) and an additional assessment of micropollutants on two PP. Eleven PP hosting different treatment processes were monitored. Removal of biological oxygen demand (BOD) was high in all plants (>91%). Six out of the 11 PP provided good phosphorus removal (>71%). Small degrees of nitrification were observed in almost all the facilities, despite the low temperatures, while denitrification was only observed in two plants which achieved the highest nitrification rates (>51%) and had sludge recirculation. No strong correlation between wastewater temperature and BOD, nutrients and indicator bacteria concentration in the effluents was found. The high data variability and the effects of other process parameters as well as snow-melt water infiltration are suggested as possible reasons for the lack of correlation. However, weak negative relations between effluent concentrations and wastewater temperatures were detected in specific plants, indicating that temperature does have effects. When managed adequately, package plants can provide high BOD and phosphorus removal, but nitrogen and bacteria removal remain challenging, especially at low temperatures. Pharmaceutical compounds were detected in the effluents at concentrations within or above ranges reported for large treatment plants while phthalate ester concentrations were below commonly reported effluent concentrations.

Gully pots (GPs) are ubiquitously used in urban catchments, to direct surface runoff into piped sewer systems, reduce the risk of sediment-induced pipe blockages and the loading of solids and associated contaminants on the receiving waters. Over time, the build-up of sediments in GPs will lead to impaired hydraulic performance, putting the urban catchment at risk of flooding. However, GP maintenance strategies lack both a robust evidence base and clear aims against which their effectiveness can be benchmarked. An improved understanding of the factors influencing long-term in-situ solids accumulation in GPs is required for further assessment and optimisation of the GP maintenance scheme. As a contribution to addressing these knowledge gaps, sediments from 27 GPs located in urban catchments associated with three street feature types (roundabout; crossing; straight road) and varied traffic intensities were collected on two occasions, representing two distinct seasonal accumulation periods. Parameters including GP fullness levels, particle size distribution (PSD), and solids mass accumulation rates were evaluated with regards to the impacts of seasonal activities, traffic conditions as well as configuration and dimension of GPs. The results indicate impacts of seasonal activities on solids accumulation rates were not consistent across all GPs, with the magnitude of the difference larger following winter-spring catchment practices. Additionally, synergistic impacts of seasonal activities and traffic conditions on PSD and solids accumulation rates were observed. For example, the winter road safety measures may enhance the impacts of the characteristic vehicle turning motions at roundabouts, contributing to the negative correlation identified between traffic intensities and solids accumulation rates. The overall exhibited large variations in sump fullness levels (4 %–73 %) and solids dry mass (0.5–51 kg) directly challenged the commonly adopted generalised GP maintenance frequency without taking the catchment-specific activities into consideration.

Gully pots actively trap sediments transported by urban runoff to prevent in-pipe blockages and surface flooding. However, due to poor maintenance (resulting in sediment build-up) and increasingly extreme wet weather events, the scour of previously-deposited sediments from gully pots is identified as a potential contributor to EU Water Framework Directive failure. While basal sediment scour deterministic models have been developed and validated using laboratory and field gully pot data sets, the ability of these models to predict behaviour at sites other than those for which they were established has not been addressed. Nor has the impact of future rainfall predictions on the role of gully pots as sediment sources been systematically examined. As a contribution to addressing these knowledge gaps, the performance of two gully pot basal sediment scour models of distinct complexity levels are evaluated under current and future rainfall conditions. The output from Model One suggests that the scour-induced total suspended solids in gully pot discharge can be kept well below 25 mg/L if the gully pot fullness level is maintained at under 60%. Results identify the opportunity to incorporate the actual/targeted ecological status of recipients in scheduling gully pot maintenance operations and that proactive gully pots maintenance will reduce the impacts of increased rainfall intensity/duration on the magnitude of sediment scour. Results from Model Two suggest that fine sediments are particularly susceptible to in-pot scour. For example, sediment with a specific gravity of 1.1 and diameter of >63 μm accounts for 50% of scour-induced total suspended solids in gully pot discharge. The effluent suspended solids concentrations predicted by the two models differ by up to two orders of magnitude. However, without further empirical field data pertaining to their respective competences/applications, neither model could be discounted at this stage. For example, the use of Model One is more appropriate in the establishment of gully pot maintenance schedules, with Model Two more suited to the dimensioning of gully pots based on performance requirements. This application, however, relies on the development and adoption of a more stringent regulation on gully pots discharge.

The surface infiltration rates (SIR) of permeable pavements decline with time as sediment and debris clog pore spaces. Effective maintenance techniques are needed to ensure the hydraulic functionality and water quality benefits of this stormwater control. Eight different small-scale and full-scale maintenance techniques aimed at recovering pavement permeability were evaluated at ten different permeable pavement sites in the USA and Sweden. Maintenance techniques included manual removal of the upper 2 cm of fill material, mechanical street sweeping, regenerative-air street sweeping, vacuum street sweeping, hand-held vacuuming, high pressure washing, and milling of porous asphalt. The removal of the upper 2 cm of clogging material did not significantly improve the SIR of concrete grid paves (CGP) and permeable interlocking concrete pavers (PICP) due to the inclusion of fines in the joint and bedding stone during construction, suggesting routine maintenance cannot overcome improper construction. For porous asphalt maintenance, industrial hand-held vacuum cleaning, pressure washing, and milling were increasingly successful at recovering the SIR. Milling to a depth of 2.5 cm nearly restored the SIR for a 21-year old porous asphalt pavement to like-new conditions. For PICP, street sweepers employing suction were shown to be preferable to mechanical sweepers; additionally, maintenance efforts may become more intensive over time to maintain a threshold SIR, as maintenance was not 100% effective at removing clogging material.

Olive mill wastewater (OMWW) is a major problem in olive oil – producing countries, due to its high organic load and concentration in phenols that are toxic for marine life, plants and soil microorganisms. In the present study, two mushroom species were tested in regard to their OMWW's oxidative capacity, Pleurotus citrinopileatus LGAM 28684 and Irpex lacteus LGAM 238. OMWW (25% v/v) degradation was investigated for several culture conditions, namely pH, agitation speed, nitrogen-based supplements and their concentration. The selected values were pH 6, agitation rate 150 rpm, 30 g L−1 corn steep liquor as nitrogen source for P. citrinopileatus and 20 g L−1 diammonium tartrate for I. lacteus. The two strains performed well in cultures supplemented with OMWW, generating very high titers of oxidative enzymes and achieving more than 90% color and phenols reduction within a 24 days cultivation period. In addition, the amount of glucans present in the fungal biomass was assessed. Hence, P. citrinopileatus and I. lacteus appear as potent degraders of OMWW with the ability to use the effluent as a substrate for the production of biotechnologically important enzymes and valuable fungal glucans.