Tailoring gas-phase CO2 electroreduction selectivity to hydrocarbons at Cu nanoparticles.

Copper-based surfaces appear as the most active catalysts for CO2 electroreduction to hydrocarbons, even though formation rates and efficiencies still need to be improved. The aim of the present work is to evaluate the continuous gas-phase CO2 electroreduction to hydrocarbons (i.e. ethylene and methane) at copper nanoparticulated-based surfaces, paying attention to particle size influence (ranging from 25-80 nm) on reaction productivity, selectivity, and Faraday efficiency (FE) for CO2 conversion. The effect of the current density and the presence of a microporous layer within the working electrode are then evaluated. Copper-based gas diffusion electrodes are prepared by airbrushing the catalytic ink onto carbon supports, which are then coupled to a cation exchange membrane (Nafion) in a membrane electrode assembly. The results show that the use of smaller copper nanoparticles (25 nm) leads to a higher ethylene production (1148 µmol m-2 s-1) with a remarkable high FE (92.8%), at the same time, diminishing the competitive hydrogen evolution reaction in terms of FE. This work demonstrates the importance of nanoparticle size on reaction selectivity, which may be of help to design enhanced electrocatalytic materials for CO2 valorization to hydrocarbons.

Waste management under a life cycle approach as a tool for a circular economy in the canned anchovy industry.

The anchovy canning industry has high importance in the Cantabria Region (North Spain) from economic, social and touristic points of view. The Cantabrian canned anchovy is world-renowned owing to its handmade and traditional manufacture. The canning process generates huge amounts of several food wastes, whose suitable management can contribute to benefits for both the environment and the economy, closing the loop of the product life cycle. Life cycle assessment methodology was used in this work to assess the environmental performance of two waste management alternatives: Head and spine valorisation to produce fishmeal and fish oil; and anchovy meat valorisation to produce anchovy paste. Fuel oil production has been a hotspot of the valorisation of heads and spines, so several improvements should be applied. With respect to anchovy meat valorisation, the production of polypropylene and glass for packaging was the least environmentally friendly aspect of the process. Furthermore, the environmental characterisation of anchovy waste valorisation was compared with incineration and landfilling alternatives. In both cases, the valorisation management options were the best owing to the avoided burdens associated with the processes. Therefore, it is possible to contribute to the circular economy in the Cantabrian canned anchovy industry.

Life cycle assessment modelling of waste-to-energy incineration in Spain and Portugal.

In recent years, waste management systems have been evaluated using a life cycle assessment (LCA) approach. A main shortcoming of prior studies was the focus on a mixture of waste with different characteristics. The estimation of emissions and consumptions associated with each waste fraction in these studies presented allocation problems. Waste-to-energy (WTE) incineration is a clear example in which municipal solid waste (MSW), comprising many types of materials, is processed to produce several outputs. This paper investigates an approach to better understand incineration processes in Spain and Portugal by applying a multi-input/output allocation model. The application of this model enabled predictions of WTE inputs and outputs, including the consumption of ancillary materials and combustibles, air emissions, solid wastes, and the energy produced during the combustion of each waste fraction.

Assessment of soil pollution based on total petroleum hydrocarbons and individual oil substances.

Different oil products like gasoline, diesel or heavy oils can cause soil contamination. The assessment of soils exposed to oil products can be conducted through the comparison between a measured concentration and an intervention value (IV). Several national policies include the IV based on the so called total petroleum hydrocarbons (TPH) measure. However, the TPH assessment does not indicate the individual substances that may produce contamination. The soil quality assessment can be improved by including common hazardous compounds as polycyclic aromatic hydrocarbons (PAHs) and aromatic volatile hydrocarbons like benzene, toluene, ethylbenzene and xylenes (BTEX). This study, focused on 62 samples collected from different sites throughout The Netherlands, evaluates TPH, PAH and BTEX concentrations in soils. Several indices of pollution are defined for the assessment of individual variables (TPH, PAH, B, T, E, and X) and multivariables (MV, BTEX), allowing us to group the pollutants and simplify the methodology. TPH and PAH concentrations above the IV are mainly found in medium and heavy oil products such as diesel and heavy oil. On the other hand, unacceptable BTEX concentrations are reached in soils contaminated with gasoline and kerosene. The TPH assessment suggests the need for further action to include lighter products. The application of multivariable indices allows us to include these products in the soil quality assessment without changing the IV for TPH. This work provides useful information about the soil quality assessment methodology of oil products in soils, focussing the analysis into the substances that mainly cause the risk.

Assessment of regional metal levels in ambient air by statistical regression models.

The assessment of the particulate matter (PM) levels and its constituents presented in the atmosphere is an important requirement of the air quality management and air pollution abatement. The heavy metal levels in PM10 are commonly evaluated by experimental measurements; nevertheless, the EC Directives also allow the Regional Governments to estimate the regulated metal levels (Pb in Directive 2008/50/EC and As, Ni and Cd in Directive 2004/107/EC) by objective estimation and modelling techniques. These techniques are proper alternatives to the experimental determination because the required analysis and/or the number of required sampling sites are reduced. The present work aims to estimate the annual levels of regulated heavy metals by means of multivariate linear regression (MLR) and principal component regression (PCR) at four sites in the Cantabria region (Northern Spain). Since the objective estimation techniques may only be applied when the regulated metal concentrations are below to the lower assessment threshold, a previous evaluation of the determined annual levels of heavy metals is conducted to test the fulfilment of the EC Directives requirements. At the four studied sites, the results show that the objective estimations are allowed alternatives to the experimental determination. The annual average metal concentrations are well estimated by the MLR technique in all the studied sites; furthermore, the EC quality requirements for the objective estimations are fulfilled by the developed statistical MLR models. Hence these estimations may be used by Regional Governments as a proper alternative to the experimental measurements for the regulated metal levels assessment.

Food waste management during the COVID-19 outbreak: a holistic climate, economic and nutritional approach.

Improving the food supply chain efficiency has been identified as an essential means to enhance food security, while reducing pressure on natural resources. Adequate food loss and waste (FLW) management has been proposed as an approach to meet these objectives. The main hypothesis of this study is to consider that the "strong fluctuations and short-term changes" on eating habits may have major consequences on potential FLW generation and management, as well as on GHG emissions, all taking into account the nutritional and the economic cost. Due to the exceptional lockdown measures imposed by the Spanish government, as a consequence of the emerging coronavirus disease, COVID-19, food production and consumption systems have undergone significant changes, which must be properly studied in order to propose strategies from the lessons learned. Taking Spain as a case study, the methodological approach included a deep analysis of the inputs and outputs of the Spanish food basket, the supply chain by means of a Material Flow Analysis, as well as an economic and comprehensive nutritional assessment, all under a life cycle thinking approach. The results reveal that during the first weeks of the COVID-19 lockdown, there was no significant adjustment in overall FLW generation, but a partial reallocation from extra-domestic consumption to households occurred (12% increase in household FLW). Moreover, the economic impact (+11%), GHG emissions (+10%), and the nutritional content (-8%) complete the multivariable impact profile that the COVID-19 outbreak had on FLW generation and management. Accordingly, this study once again highlights that measures aimed at reducing FLW, particularly in the household sector, are critical to make better use of food surpluses and FLW prevention and control, allowing us to confront future unforeseen scenarios.

Potential formation of PCDD/Fs in triclosan wastewater treatment: An overall toxicity assessment under a life cycle approach.

Wastewater may contain a diverse group of unregulated pollutants known as emerging pollutants, such as pharmaceuticals and personal care products (PPCPs). Triclosan (TCS) is a personal care product widely used as an antiseptic or preservative in cosmetics, hand wash, toothpaste and deodorant soaps. Advanced oxidation processes (AOPs) have been used as effective and alternative treatments for complex wastewater. However, an important criterion for the assessment of AOPs and their operation conditions could be the potential formation of new toxic secondary products, such as polychlorinated dibenzo-p-dioxins and furans (PCDD/Fs), especially when emerging pollutants are present in the media. If these are omitted from environmental management studies, the real environmental impacts of a WWTPs (wastewater treatment plants) may be underestimated. Consequently, the current study aims to evaluate the environmental impacts derived from electrooxidation (EOX), one of the most effective oxidation technologies, of emerging pollutants using Life Cycle Assessment. The analyses were performed for the treatment of effluents containing TCS, firstly without considering the formation of PCDD/Fs and, thereafter, considering the effects of these compounds. Total toxicity, calculated through different methods and corresponding impact factors, were evaluated for each stage of the process when different electrolytes are used, including PCDD/Fs formation. Finally, a sensitivity analysis was carried out to study i) the effect of the TCS initial concentration on the environmental impacts associated to ecotoxicity for the different life cycle methods and ii) the influence of changing the organic pollutant on PCDD/Fs formation employing 2-chlorophenol (2-CP). As a result, LCIA methods demonstrate that they are not fully adapted to the computation of PCDD/Fs in the water compartment, since only 2,3,7,8-tetraclorodibenzo-p-dioxina (2,3,7,8-TCDD) is present as a substance in the impact categories assessed, ignoring the remaining list of PCDD/Fs.

Combined application of Life Cycle Assessment and linear programming to evaluate food waste-to-food strategies: Seeking for answers in the nexus approach.

The great concern regarding food loss (FL) has been studied previously, but in an isolated way, disregarding interdependencies with other areas. This paper aims to go a step further by proposing a new procedure to assess different waste management alternatives based on the nexus approach by means of an integrated Water-Energy-Food-Climate Nexus Index (WEFCNI). The environmental profile of the waste management techniques is determined using Life Cycle Assessment (LCA) which, in combination with Linear Programming (LP), explores the optimal aggregation of weighting factors that lead to an aggregated nexus index. The management of residues from the anchovy canning industry in Cantabria (Spain) has been used as a case study, considering the three current applied alternatives: (i) valorisation of FL as animal feed in aquaculture (food waste-to-food approach), (ii) incineration of FL with energy recovery, and (iii) landfilling with biogas recovery. The last two considered the use of energy recovered to produce a new aquaculture product (food waste-to-energy-to-food scenarios). The results indicate that incineration is the best performing scenario when the nutritional energy provided by the valorisation alternative is not high enough and the valorisation technology presents the highest water consumption. Therefore, a minimisation in the consumption of natural resources is suggested in order to improve the application of circular economy within the sector. The use of the nexus index as an environmental management tool is extendable to any food system with the aim of facilitating the decision-making process in the development of more sustainable products.

Calcium fluoride recovery from fluoride wastewater in a fluidized bed reactor.

In order to contribute to better resource efficiency and industrial waste management leading to a sustainable production and consumption pattern new processes must be developed, which should be operated in such a way that waste production is reduced or avoided. Fluoride removal by precipitation generates huge amounts of a water rich sludge. Calcium fluoride is not recovered from the waste streams and it is not recycled due to the high water content and the low quality of the sludge. Crystallization process in a fluidized bed reactor (FBR) appears as an alternative technology to the conventional chemical precipitation process. In the crystallization process in a FBR silica sand is usually used as seed material, however silica is a deleterious impurity because it causes losses in the yield of HF and its content should be less than 1%. In this paper, granular calcite has been used as seed material in order to obtain synthetic calcium fluoride. According to the composition (CaF(2)>97%, SiO(2)<1%), the synthetic calcium fluoride from the crystallization process in a FBR is able to be recycled as raw material for the manufacture of hydrofluoric acid leading to a reduction of raw materials consumption. The crystallization process in a FBR to remove fluoride from industrial wastewaters contributes to an environmental friendly production, because it allows to reduce the waste production as well as to increase the recovery of materials.

Distribution of butyltin and derivatives in oyster shells and trapped sediments of two estuaries in Cantabria (Northern Spain).

Distribution of butyltin compounds (BTs) and derivatives (monobutyltin, MBT; dibutyltin, DBT and tributyltin, TBT) was analysed in Crassostrea gigas oyster shells and the sediments trapped in the shell chambers, from two different estuaries in Cantabria (Northern Spain), with very different environmental conditions, where previous data have not been reported. Inorganic tin analysis in oyster shells was performed in order to study the degradation of BTs. Shell thickening and losses in biological growth are related with the presence of TBT, and were determined using three morphological indexes. Total BTs concentrations, expressed as Sn, ranged from 18.0 ng g(-1) to 176.7 ng g(-1) in sediments, and from 2.4 ng g(-1) to 11.1 ng g(-1) in oyster shells. Total inorganic tin concentrations ranged from 1775.0 ng g(-1) to 4781.3 ng g(-1) in oyster shells. The amount of BTs in oyster shells has been associated with the concentrations in the sediments trapped in the shell chambers. Partition coefficients between oyster sediments and oyster shells show the affinity of BTs by the sediments and the higher inorganic tin in oyster shells does not seem to be related to the BTs pollution.

The Energy-Water-Food Nexus.

As the global population grows in size and increasingly lives in cities, and with lifestyles based on greater material consumption, more attention is being given to the integrated system that supplies our energy, water, and food, the Nexus. There is also mounting concern about effects on the Nexus of climate change and damage to the natural environment that provides essential ecosystem services. Nexus analysis applies existing techniques, such as computational modelling and Life Cycle Assessment, but new frameworks and tools are needed, including those that will integrate societal and technical dimensions. Case studies show the vital role played by stakeholder involvement in clarifying issues, priorities, and values. They also demonstrate the importance of an integrated systems view of the complex interrelationships of the Nexus when planning effective remedies. Assessments conclude that transformative social and political change is needed to create new structures, markets, and governance to deal with the Nexus if we are to meet agreed-upon sustainable development goals.

A comparative study between the fluxes of trace elements in bulk atmospheric deposition at industrial, urban, traffic, and rural sites.

The input of trace elements via atmospheric deposition towards industrial, urban, traffic, and rural areas is quite different and depends on the intensity of the anthropogenic activity. A comparative study between the element deposition fluxes in four sampling sites (industrial, urban, traffic, and rural) of the Cantabria region (northern Spain) has been performed. Sampling was carried out monthly using a bulk (funnel bottle) sampler. The trace elements, As, Cd, Cr, Cu, Mn, Mo, Ni, Pb, Ti, Zn, and V, were determined in the water soluble and insoluble fractions of bulk deposition samples. The element deposition fluxes at the rural, urban, and traffic sites followed a similar order (Zn > Mn> > Cu ≈ Ti > Pb > V ≈ Cr > Ni> > As ≈ Mo > Cd). The most enriched elements were Cd, Zn, and Cu, while V, Ni, and Cr were less enriched. An extremely high deposition of Mn was found at the industrial site, leading to high enrichment factor values, resulting from the presence of a ferro-manganese/silico-manganese production plant in the vicinity of the sampling site. Important differences were found in the element solubilities in the studied sites; the element solubilities were higher at the traffic and rural sites, and lower at the urban and industrial sites. For all sites, Zn and Cd were the most soluble elements, whereas Cr and Ti were less soluble. The inter-site correlation coefficients for each element were calculated to assess the differences between the sites. The rural and traffic sites showed some similarities in the sources of trace elements; however, the sources of these elements at the industrial and rural sites were quite different. Additionally, the element fluxes measured in the insoluble fraction of the bulk atmospheric deposition exhibited a good correlation with the daily traffic volume at the traffic site.

Environmental assessment of polycyclic aromatic hydrocarbons (PAHs) in surface sediments of the Santander Bay, Northern Spain.

Samples of intertidal surface sediments (0-2 cm) were collected in 17 stations of the Santander Bay, Cantabric Sea, Northern Spain. The concentrations of polycyclic aromatic hydrocarbons (PAHs), 16, were analysed by HPLC and MS detection. Surface sediments show a good linear correlation among the parameters of the experimental organic matter evaluation, where total carbon (TC) and loss on ignition (LOI) are approximately 2.5 and 5 times total organic carbon (TOC). A wide range of TOC from 0.08% to 4.1%, and a broad distribution of the sum of sigma16PAHs, from 0.02 to 344.6 microg/g d.w., which can be correlated by an exponential equation to the TOC, has been identified. A qualitative relationship may be established between the industrial input along the rivers and the concentration of sigma6PAHs in the sediments of the estuaries: Boo estuary (8404-4631 microg/g OC), Solia-San Salvador estuaries (305-113 microg/g OC) and Cubas estuary (31-32 microg/g OC). This work shows a dramatic change in the spatial distribution in the concentration of PAHs of intertidal surface sediments. The left edge of the Bay has the main traffic around the city and the major source of PAHs is from combustion processes and estuarine inputs, leading to medium values of PAHs in the sediments; the right edge of the Bay has much lesser anthropogenic activities leading to lower values of PAHs in sediments. The distribution of individual PAHs in sediments varies widely depending on their structure and molecular weight; the 4-6 ring aromatics predominate in polluted sediments due to their higher persistence. The isomer ratio does not allow any clear identification of the PAHs origin. Environmental evaluation according to Dutch guidelines and consensus sediment quality guidelines based on ecotoxicological data leads to the same conclusion, sediments in the Santander Bay show a very different environmental quality depending on the spatial position from heavily polluted/medium effects to non-polluted/below threshold effects. These results indicate that local sources of PAHs, especially estuary discharges, lead to very different qualities of sediments in coastal zones, where traffic and industrial activities take place.

Environmental behavior of cement-based stabilized foundry sludge products incorporating additives.

A series of experiments were conducted to stabilize the inorganic and organic pollutants in a foundry sludge from a cast iron activity using Portland cement as binder and three different types of additives, organophilic bentonite, lime and coal fly ash. Ecotoxicological and chemical behavior of stabilized mixes of foundry sludge were analyzed to assess the feasibility to immobilize both types of contaminants, all determined on the basis of compliance leaching tests. The incorporation of lime reduces the ecotoxicity of stabilized mixes and enhances stabilization of organic pollutants obtaining better results when a 50% of cement is replaced by lime. However, the alkalinity of lime increases slightly the leached zinc up to concentrations above the limit set under neutral conditions by the European regulations. The addition of organophilic bentonite and coal fly ash can immobilize the phenolic compounds but are inefficient to reduce the ecotoxicity and mobility of zinc of final products.

Characterization of metal finishing sludges: influence of the pH.

Metal finishing sludges are classified as metal hydroxide hazardous wastes due to the heavy metal release to the environment. This release, commonly determined by compliance lixiviation tests based on the equilibrium conditions at the end of the leaching experiment, is mainly dependent on the pH of the solution. In this work, the leaching behaviour of Cd, Cr, Cu, Fe, Ni, Pb and Zn, of the 32 metal finishing sludges coming from 16 European industrial facilities, and using the distilled water compliance test DIN 38414-S4, have been studied. The concentrations of chromium and copper in the leachates do not follow the solubility evolution of their hydroxide with the pH. The simple assumption of a heavy metal concentration in the leachate directly related to the solubility of the hydroxide is not in good agreement with the experimental results of the distilled water leaching test, probably due to the presence of different species, which can contribute to the metal mobility depending on the sludge composition. An experimental evaluation of the easily available amount of metals in real wastes seems to be necessary for disposal assessment. This paper contains valuable information, from orderly handling metal finishing wastes to the statistical studies of production and management of wastes suggested recently by the Commission of the European Community.

Environmental assessment of lubricants before and after wire drawing process.

Iron wire drawing processes involve the use of solid lubricants made of powdered raw materials, which lead to industrial wastes after being used. These wastes, based on stearates, have a negative effect on the environment. This study deals with the environmental assessment of some lubricants before and after the wire drawing process in a Spanish factory. The parameters evaluated for this study have been total organic carbon (TOC), mobility of zinc and lead, and ecotoxicity (EC(50)). Results show that wastes have more ecotoxicity than the original lubricants due to the content of metals that lubricants pick up from the wire, as pickling, patenting and galvanising take part in the manufacture. The capture of metallic particles leads to a reduction of TOC and an increase in ecotoxicity.

Waste minimisation in a hard chromiun plating Small Medium Enterprise (SME).

The high potential of waste stream minimisation in the metal finishing sector justifies specific studies of Small and Medium Enterprises (SME). In this work, the minimisation options of the wastes generated in a hard chromium plating activity have been analysed. The study has been performed in a small job shop company, which works in batch mode with big pieces. A process flowsheet after connecting the unit operations and determining the process inputs (raw and secondary materials) and outputs (waste streams) has been carried out. The main properties, quantity and current management of the waste streams have been shown. The obvious lack of information has been identified and finally the waste minimisation options that could be adopted by the company have been recorded.

Environmental assessment of cement/foundry sludge products.

This work deals with the environmental assessment of products based on cement and a waste from a cast iron activity. The waste is a foundry sludge from wastewater treatment previously characterized. This industrial waste shows a high water content (62.4%) and a hazardous behavior due to its metallic content mainly Zn (16.5%), together with a low fraction of organic pollutants, mainly phenolic compounds. The feasibility of immobilizing both typs of contaminants was studied using Portland cement as binder at different cement/waste ratios. The parameters of environmental control were the ecotoxicity and mobilization of zinc and phenolic compounds, all determined on the basis of compliance leaching tests. The acid neutralization capacity of the cement/waste products was measured in order to obtain information on their buffering capacity. Experimental results from chemical analysis of leachates led to a non ecotoxic character of cement/waste products Although the metallic ions were mobilized within the cement mattices, the organic matter did not allow the formation of monolithic forms and an efficient immobilization of phenolic compounds. Concerning the acid neutralization capacity, this parameter was shown to depend mainly on the quantity of cement, although a decrease in alkalinity was observed when the amount of water in the cement/waste products increased.

Comparative study of the destruction of polychlorinated dibenzo-p-dioxins and dibenzofurans during Fenton and electrochemical oxidation of landfill leachates.

Two advanced oxidation processes (AOPs) that provide a broad-spectrum contaminant destruction option were applied to the treatment of the leachates, namely electrochemical and Fenton oxidation. Despite the similar efficiency in the oxidation of major organic contaminants, approximately 90% reduction of chemical oxygen demand after 180 min, our results showed a different behaviour of both AOPs in the oxidation of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). A concentration reduction of 73% for 1,2,3,4,6,7,8-HpCDD and of 71% for OCDD was reached after 180 min of electrochemical oxidation and the total toxic equivalent of the sample was reduced in 58%. However, Fenton oxidation followed a different trend and for similar operation times, it was detected an increase in the concentration of several PCDD/Fs congeners, specially stressed for the major congeners 1,2,3,4,6,7,8-HpCDD, OCDD and OCDF, and in the total toxicity of the sample between 12.5% and 128%. Comparison of the results and the rationale behind their difference are finally discussed.

Impact of the global economic crisis on metal levels in particulate matter (PM) at an urban area in the Cantabria Region (Northern Spain).

Air pollution by particulate matter is well linked with anthropogenic activities; the global economic crisis that broke out in the last year may be a proper indicator of this close relationship. Some economic indicators show the regional effects of the crisis on the Cantabria Region. The present work aims to evaluate the impact of the economic crisis on PM10 levels and composition at the major city of the region, Santander. Some metals linked to anthropogenic activities were measured at Santander and studied by Positive Matrix Factorization; this statistical analysis allowed to identify three main factors: urban background, industrial and molybdenum-related factor. The main results show that the temporal trend of the levels of the industrial tracers found in the present study are well agree with the evolution of the studied economic indicators; nevertheless, the urban background tracers and PM10 concentration levels are not well correlated with the studied economic indicators.