Special Issue « ECOTOX, the INRA's network of ecotoxicologists »

The fractionation of a protein hydrolysate obtained from tuna processing by-products by means of a membrane cascade integrating ultrafiltration (UF) and nanofiltration (NF) membranes was proposed in order to separate and purify the protein fraction between 1 and 4 kDa, which is the most interesting for nutraceutical purposes. A simulation model, based on mass balances and empirical equations for describing permeate flux and rejection of protein fractions, was developed and complemented with a simple cost estimation model. The product purity (49.3 %) and the process yield (62.6 %) were independent of the total water consumption of the process, but high water consumptions were required to maintain the total protein content of the stream below upper bounds that assured the absence of membrane clogging. The implementation of a water recovery system, based on an additional tight NF stage, implied improvements in both environmental and economic aspects of the process.

The evaluation of the spatial representativeness of air quality monitoring stations is of fundamental relevance when observed concentration levels are used in air quality assessment. Since no reference method is provided, there is a need to develop tools for its quantitative assessment. In this paper we test a recently developed methodology for spatial representativeness area assessment, based on the analysis of time series of model concentrations by means of a Concentration Similarity Frequency (CSF) function, on the Taranto-via Machiavelli industrial monitoring station, located in a mid-size city in Southern Italy. The complex territorial context, the peculiar anthropogenic emissions features, dominated by the contribution of the largest steelworks in Europe, and the critical situation of human health in the city make this application an interesting case study to assess the portability of the CSF approach, so far applied only to background stations, to industrial sites that experience high concentration variability. A comprehensive characterization of the main anthropogenic emissions of the area was carried out, with detailed treatment of dust emission by wind erosion from industrial mineral piles; a Lagrangian modelling approach was chosen to simulate PM10 dispersion patterns, to achieve a reliable and high resolution description of concentration variability around the site. The resulting representativeness area of the station is 0.067 km², fulfilling EU prescriptions for industrial stations. The comprehensive evaluation results, through the comparison with the observed data, showed good performances pointing out the reliability of the estimated concentration fields around the site and consequently of the assessment of its representativeness area.

This work proposes the use of the life cycle assessment (LCA) to identify the best available techniques (BAT) to the management of the residues generated in the anchovy canning sector. This industry generates huge amount of solid and liquid wastes, and their management is one of the hotspots of the canned anchovy life cycle. The application of BATs can improve the environmental performance of the canned anchovy. However, sometimes it is not clear which BAT is the most appropriated, and an environmental analysis is required. In this sense, several BATs are proposed based on the circular economy concept, which promotes the reutilisation of wastes and they were evaluated under a life cycle approach: (i) valorisation of the anchovy residues into fishmeal, fish oil and anchovy paste, (ii) incineration and (iii) disposal in a municipal solid waste landfill. The LCA was conducted from cradle to gate using the global warming (GW) indicator. The results showed that the disposal of the anchovy residues in a landfill was the least environmental-friendly option, while the valorisation was the best alternative. | Authors thank to Ministry of Economy and Competitiveness of Spanish Government for the financial support through the project called GeSAC-Conserva: Sustainable Management of the Cantabrian Anchovies (CTM2013-43539-R). Jara Laso also thanks to the Ministry of Economy and Competitiveness of Spanish Government for the financial support through the research fellowship BES-2014-069368.

The chlor-alkali industry sector produces chlorine, sodium/potassium hydroxide and hydrogen by the electrolysis of brine. Nowadays, three different electrolysis techniques are applied: mercury, diaphragm, and membrane cell technology. From all these technologies, the European Commission labels the membrane process as the Best Available Technique (BAT) for the chlor-alkali industry. The membrane cell technology has fewer exhausts to the environment and it is relatively more efficient in the use of electric power that mercury and diaphragm. Nevertheless, despite the fact that the overall energy intensity has been reduced, the issue of energy consumption is still a major matter. A promising approach for reducing the electricity demand of chlor-alkali electrolysis is using oxygen-depolarised cathodes (ODC). ODCs are long known and have been successfully used in chlorine production through electrolysis of hydrogen chloride (HCl). The achieved environmental benefit of this technique is a reduction of energy consumption. However, the overall reduction of energy consumption is lower, as some energy is required to produce pure oxygen and because hydrogen is not co-produced, which could otherwise be used in chemical reactions or to produce steam and electricity via combustion or fuel cells. In this sense, the reduced electricity demand does not necessarily imply cleaner chlorine production. For that reason, this work proposes the use of the life cycle assessment (LCA) methodology to determine the environmental performance of the existing electrolysis technologies and to compare it with the ODC technique.

We measured the concentrations of dissolved inorganic nitrogen (DIN; nitrate, ammonium, and nitrite) in stream water in a paddy-dominated agricultural basin in a snowfall area from August 2009 to October 2010 to facilitate evaluation of stream water eutrophication from nitrogen during the non-irrigated period. We compared the nitrogen budget in a paddy field between irrigated and non-irrigated periods, from information about nitrogen fertilizer, denitrification, harvested rice, and atmospheric nitrogen deposition. We also estimated stream nitrogen exports from DIN concentrations and stream flow rates. DIN concentrations in stream water were higher during the non-irrigated period (October–March) than during the irrigated period (April–September). Stream flow was also higher during the non-irrigated period (5.9 mm day⁻¹) than during the irrigated period (2.5 mm day⁻¹), which possibly reflects snow melting. Although nitrogen fertilizer was applied during the irrigated period, the amount of nitrogen removed by the rice harvest and denitrification was sufficiently large to reduce nitrogen exports from paddy fields. Atmospheric nitrogen deposition was higher during the non-irrigated period (755 kg N km⁻²) than during the irrigated period (410 kg N km⁻²). DIN exports were also higher in the non-irrigated period (860 kg N km⁻²) than in the irrigated period (120 kg N km⁻²). The higher exports in the non-irrigated period may reflect the lack of nitrogen removal by a rice harvest and denitrification and increased runoff and higher atmospheric nitrogen deposition. Our study highlights the important contribution of the non-irrigated period to nitrogen eutrophication in stream water in this particular environment.

Microcystis aeruginosa is a common cause of algal bloom outbreaks in Chinese lakes. This study investigated the effects of phosphate loading on the algal growth and extracellular organic matter (EOM) production of M. aeruginosa. The cell density was monitored by cell counting, and EOMs were characterized by dissolved organic carbon (DOC), carbohydrate, protein, and excitation/emission matrix fluorescence spectroscopy (EEM). DOC concentration peaked during the stationary phase and was contributed primarily by amino acid- and fulvic-like substances. Carbohydrate was a substantially larger fraction than protein. Phosphate showed positive influence on the cell growth and EOMs. As its concentration increased, the EOMs concentration increased. So did EOM and β-ionone as typical taste and odor compounds. Whatever the phosphate concentration was, the peak of β-ionone concentration exceeded its odor threshold (7.0 ng/L), resulting in a severe fruit-like odor. Additionally, the disinfection by-products involved with EOM were evaluated in both chlorination and chloramination, indicating that trihalomethanes were the dominated toxic by-products and the chloramination showed more significant effect on its formation as an interesting result.

Pilot scale thin film plate reactors (TFPR) were fabricated to study the solar photocatalytic treatment of wastewater obtained from the secondary treatment plant of a sugar refinery. Silver-impregnated titanium dioxide (TiO₂) was prepared by a facile chemical reduction method, characterized, and immobilized onto the surface of ceramic tiles used in the pilot scale reactors. On 8 h of solar irradiation, percentage reduction of chemical oxygen demand (COD) of the wastewater by Ag/TiO₂, pure TiO₂, and control (without catalyst) TFPR was about 95, 86, and 22 % respectively. The effects of operational parameters such as, flow rate, pH, and addition of hydrogen peroxide (H₂O₂) were optimized as they influence the rate of COD reduction. Under 3 h of solar irradiation, 99 % COD reduction was observed at an optimum flow rate of 15 L h⁻¹, initial pH of 2, and addition of 5 mM of H₂O₂. The results show that Ag/TiO₂ TFPR could be effectively used for the tertiary treatment of sugar refinery effluent using sunlight as the energy source. The treated water could be reused for industrial purposes, thus reducing the water footprint of the industry. Graphical Abstract Sugar refinery effluent treatment by solar photocatalytic TFPR