Search

International audience; Bioeconomy addresses the triple balancing challenge posed by the Paris Agreement: inducing additional GHG mitigation alongside biophysical carbon dioxide removals, while keeping fossil carbon in the ground. The use of woody plants as construction materials could simultaneously address this challenge: CO2 is absorbed through photosynthesis, while wood-based products provide mitigation by replacing either petrochemical materials such as plastic boards or energy-intensive materials like bricks. This study combines, at the scale of France, static and dynamic life cycle assessment with soil carbon simulations to investigate the long-term environmental performance of using, as input for the building sector, black locust (Robinia pseudoacacia L.) planted on “carbon vulnerable lands”. These are areas specifically selected for their low soil organic carbon (SOC) levels and low potential to interfere with food security. After the consecutive cultivation of three rotations, black locust was shown to stock an additional 92000 kg ha−1 of carbon in soils as SOC. The mitigation effect from the plastic board replacement is the major contributor to the assessed environmental impacts, including climate change, leading the black locust system to generally perform better than the reference system where the carbon vulnerable areas are left as they are with their initial vegetation. Considering that cultivation starts in 2022, the dynamic evaluation of the global mean temperature change (GMTC) shows that the black locust system results in net negative emissions in the near- and mid-term, but with a GMTC overshot in the second half of the century. Even if a considerable carbon stock is created through time (e.g., 81% and 39% of the carbon captured by photosynthesis, in 2050 and 2100 respectively), the GHG emissions stemming from manufacturing and end-of-life processes were shown to offset the benefit of carbon capture.

The removal of additional carbon dioxide from the atmosphere is indispensable for controlling global warming. This study proposed the concept of ‘biopump’, as plants capable of significantly transferring carbon into the soil. The Carbon Storage in Arable land and Anthropogenic Products (CSAAP) relates to the cultivation of ‘biopumps’ on marginal arable lands poor in soil organic carbon (SOC) and their conversion into long-lived anthropogenic products. Based on a list of twenty-seven biopumps assembled from a literature review, this study proposed a method for the regional prioritization of biopumps, considering among others their ability to increase SOC and adaptation. A list with eight woody and eight herbaceous biopumps was recommended for France. To illustrate the potential of the CSAAP strategy for products encompassing a variety of lifetimes, carbon flows, from biopump cultivation to biomaterial manufacturing and end-of-life, were tracked in time to calculate their influence on global mean temperature change. An illustration was performed on the basis of a French case study, where Miscanthus is grown on spatially identified marginal lands quantified as 11,187- 24,007 km2. Planting biopumps on these lands could increase by 0.23 to 0.49 Mt carbon stocked as SOC annually, which represents 0.19%- 0.41% of the annual French carbon budget during 2015-2018. If the carbon contained in the biomass is indefinitely kept in anthropogenic products, it could represent 13.07% of the same carbon budget. We concluded that biopumps could induce negative emission by 2100, with efficiency strongly depending upon carbon’ residence time in the anthroposphere.

International audience; A framework model is proposed to evaluate the actual overall growth rate of microalgae in an outdoor tubular photobioreactor. A Monte Carlo-based radiative transfer modeling approach describes the local distribution of light energy inside the broth as a function of static (reactor geometry, location) and dynamic solar radiation parameters (angle of incidence, direct and diffuse solar contribution, incident radiation intensity). The light fields are coupled to a Lagrangian discrete random walk tracking of the cells to give the light variations experienced by each microalga for different broth flow rates. The cell light experiments are combined with a dynamic biological model to statistically calculate the actual overall growth rate. Using this model, 380 numerical experiments were performed for a wide range of geographic, light, biomass concentration, and broth flow turbulence conditions. Correlations for a normalized growth rate, Gamma, relating the actual overall growth rate to its asymptotic behaviors (i.e., the instantaneous response and the full integration response), are proposed. The results clearly show that, for a fixed broth flowrate, Gamma does not change with cell concentration variation. Under given light conditions, the level of turbulence linearly manages Gamma, and thus the efficiency of sunlight utilization by the photobioreactor biomass can be tuned by the broth flow rate in the tubular photobioreactor. Gamma also increases linearly with the diffuse fraction of solar radiation. A simple correlation is proposed for fast calculation of the actual overall growth rate.

International audience; The purpose of the research is to make a first step towards rationalizing green polymeric membrane preparation. A holistic methodological approach based on metrics that consider technical, environmental, health and safety issues have been suggested to assess sustainability of membrane preparation. Metrics have been applied to solvent substitution in a non-solvent induced phase separation process. The flammability hazard of three shortlisted alternative solvents has substituted the reprotoxicity hazard of common solvents. The ultrafiltration cellulose diacetate membranes prepared with methyl lactate as solvent have a greater renewable intensity and require a lower number of solvents for their preparation. Trade-offs between use of resources (polymer, solvent, energy…) and membrane properties are inevitable. Further socio-economic, risk and life cycle analysis are crucial to fully integrate ecodesign in membrane preparation.

Climate neutrality is becoming a core long-term competitiveness factor within the aviation industry, as demonstrated by the several innovations and targets set within that sector, prior to and especially after the COVID-19 crisis. Ambitious timelines are set, involving important investment decisions to be taken in a 5-years horizon time. Here, we provide an in-depth review of alternative energy sourcing technologies for aviation revealed to date, which we classified into three main categories, namely liquid fuels (biofuels, electrofuels), electric aviation (all electric and hybrid), and carbon-free options (hydrogen-based, solar-powered). For liquid fuels, 10 pathways were reviewed, for which we supply the detailed process flow picturing all input, output, and co-products generated. The market uptake and use of these co-products were also investigated, along with the overall international regulations and targets for future aviation. As most of the inventoried pathways require hydrogen, we further reviewed six existing and emerging carbon-free hydrogen production technologies. Our review also details the five key battery technologies available (lithium-ion, advanced lithium-ion, solid-state battery, lithium-sulfur, lithium-air) for aviation, as well as the possible configuration schemes for electric propulsion (parallel electric hybrid, series electric hybrid, all electric, partial turboelectric and full turboelectric) and reflects upon the inclusion of hydrogen-powered fuel cells with these configurations. Our review studied these three categories of energy sourcing pathways as modular technologies, yet these still have to be used in a hybridized fashion with conventional fossil-based kerosene. This is among others due to an aromatics content below the standardized requirements for biofuels and electrofuels, to a too low energy storage capacity in the case of batteries, or a sub-optimal gas turbine engine in the case of cryogenic hydrogen. Yet, we found that the latter was the only available option, based on the current and emerging technologies reviewed, for a long-range aviation completely decoupled of fossil carbon. The various challenges and opportunities associated with all these technologies are summarized in this study.

International audience; Over 1.7 billion students around the world have had their education disrupted by the spread of the Coronavirus disease worldwide. Schools and universities have not faced this level of disruption since World War II. The COVID-19 pandemic presented a colossal challenge for teachers to urgently and massively adapt all their classes to distance learning in order to maintain educational continuity with the same quality. Even if some teachers and certain classes were ready to face the situation, a large majority had to adapt their teaching and learning in a very short time without training, with insufficient bandwidth, and with little preparation. This unexpected and rapid transition to online learning has led to a multiplication of teachers' strategies for distance learning in lectures, tutorials, project groups, lab works, and assessments. The purpose of this paper is to present the feedback from students and teachers who participated in the lockdown semester of two different groups of a 5-year program in Chemistry, Environment and Chemical Engineering (100 students) at INSA Toulouse (France). The analysis has highlighted some great successes and some failures in the solutions proposed. Consequently, some guidelines can be given to help us all to learn the lessons of such a singular experience in order to face the unexpected future with more knowledge and more successful distance learning. Teachers have shown very strong resilience during this crisis, at the cost of significant personal commitment. They admit that they have learned more about distance education in two months than in the last 10 years.

International audience; Innovative treatment technologies and management methods are necessary to valorise the constituents of wastewater, in particular nutrients from urine (highly concentrated and can have significant impacts related to artificial fertilizer production). The FP7 project, ValuefromUrine, proposed a new two-step process (called VFU) based on struvite precipitation and microbial electrolysis cell (MEC) to recover ammonia, which is further transformed into ammonium sulphate. The environmental and economic impacts of its prospective implementation in the Netherlands were evaluated based on life cycle assessment (LCA) methodology and operational costs. In order to tackle the lack of stable data from the pilot plant and the complex effects on wastewater treatment plant (WWTP), process simulation was coupled with LCA and costs assessment using the Python programming language. Additionally, particular attention was given to the propagation and analysis of inputs uncertainties. Five scenarios of VFU implementation were compared to the conventional treatment of 1 m(3) of wastewater. Inventory data were obtained from SUMO software for the WWTP operation. LCA was based on Brightway2 software (using ecoinvent database and ReCiPe method). The results, based on 500 iterations sampled from inputs distributions (foreground parameters, ecoinvent background data and market prices), showed a significant advantage of VFU technology, both at a small and decentralized scale and at a large and centralized scale (95% confidence intervals not including zero values). The benefits mainly concern the production of fertilizers, the decreased efforts at the WWTP, the water savings from toilets flushing, as well as the lower infrastructure volumes if the WWTP is redesigned (in case of significant reduction of nutrients load in wastewater). The modelling approach, which could be applied to other case studies, improves the representativeness and the interpretation of results (e.g. complex relationships, global sensitivity analysis) but requires additional efforts (computing and engineering knowledge, longer calculation time). Finally, the sustainability assessment should be refined in the future with the development of the technology at larger scale to update these preliminary conclusions before its commercialization.

Carbon dioxide supercritical extraction is applied to a soil artificially contaminated with biphenyl. We studied three aspects of the extraction process in order to control it. An “excess function equation of state” model is used to represent the thermodynamic properties of the binary biphenyl-carbon dioxide mixture. This model allows calculation of solid compound solubility and of liquid-gas equilibrium. The adsorption of biphenyl in soil in the presence of supercritical carbon dioxide is experimentally studied. In order to demonstrate the influence of the non-ideal character of the supercritical fluid on the amount adsorbed, we used a Bragg Williams lattice model. The adapted model allows adsorption calculation for a given set of temperature-pressure-fluid composition data. Both thermodynamic models are necessary to shape the extraction behaviour. In the soil, the pollutant is distributed between a precipitated phase and an adsorbed phase. Thus, the extraction model contains a dissolution kinetic term and a desorption kinetic term. Three parameters are unknown: the dissolution rate coefficient, the overall mass transfer coefficient between soil particles and the fluid and the fraction of precipitated biphenyl from the total quantity in soil. These parameters are estimated by fitting the model with experimental data.

The solubility of polycyclic aromatic hydrocarbons in supercritical carbon dioxide is very low, and very little experimental data exist. A method has been developed for the measurement of such low solubilities, and the solubilities of fluoranthene, chrysene, and triphenylene in a temperature range 308.15 K to 328.15 K and in a pressure range 84 bar to 251 bar have been determined. The solubilities have been fitted to the excess function-equation of state model.

The aerobic biological process is one of the best technologies available for removing hazardous organic substances from industrial wastewaters. But in the case of volatile organic compounds (benzene, toluene, ethylbenzene, p-xylene, naphthalene), volatilization can contribute significantly to their removal from the liquid phase. One major issue is to predict the competition between volatilization and biodegradation in biological process depending on the target molecule. The aim of this study was to develop an integrated dynamic model to evaluate the influence of operating conditions, kinetic parameters and physical properties of the molecule on the main pathways (biodegradation and volatilization) for the removal of Volatile Organic Compounds (VOC). After a comparison with experimental data, sensitivity studies were carried out in order to optimize the aerated biological process. Acclimatized biomass growth is limited by volatilization, which reduces the bioavailability of the substrate. Moreover, the amount of biodegraded substrate is directly proportional to the amount of active biomass stabilized in the process. Model outputs predict that biodegradation is enhanced at high SRT for molecules with low H and with a high growth rate population. Air flow rate should be optimized to meet the oxygen demand and to minimize VOC stripping. Finally, the feeding strategy was found to be the most influential operating parameter that should be adjusted in order to enhance VOC biodegradation and to limit their volatilization in sequencing batch reactors (SBR). (C) 2012 Elsevier Ltd. All rights reserved.

The calculation of solubility in supercritical fluids requires models of high precision in the near-critical region, and this is not always the case with classical models. The model proposed here is based on the relations which exist between the Heimholte energy of pure components and the excess Helmholtz energy in a mixing process at constant packing fraction. The pure component properties are represented using any equation of state which is actually included in the equation of state of the mixture. The expression of van Laar was used for the residual term of the excess function. This model was applied to the solid-fluid equilibria occurring in the binary systems composed of a hydrocarbon solid and supercritical carbon dioxide. The best results in the calculations of solubility and molar volumes of the mixture were obtained by using precise equations of state for each compound.

International audience

According to the European Construction Products Directive (89/106/EC), construction products must satisfy specified essential requirements (ER). To comply with ER 3, on hygiene, health and environment, the construction works must be designed and built in such a way that they will not be a threat to the hygiene and health of the occupants and neighbours, nor to the environment. Standardised test methods for the release of substances that are hazardous to health and environment need to be developed at the European level. A horizontal approach is considered the best route for such test development and consists of the development of a test method applicable for different products used in a certain scenario (across the fields of different Technical Committees). The work presented here regards the emission of pollutants towards soil and water and has been carried out on monolith products, based on three types of matrices: concrete, wood and metal (zinc). The aim of the work is to study the parameters (nature of leachant, temperature, liquid-to-solid ratio) that could influence the release behaviour of substances in water. The knowledge acquired from these tests will allow the identification of some parameters needed for the development of a horizontal test.

International audience

The mobility of the most water-soluble polynuclear aromatic hydrocarbons (PAHs) such as naphthalene in contaminated soils from manufactured gas plant (MGP) sites or other similar sites is influenced not only by the naturally occurring soil organic matter (SOM) but also, and in many cases mostly, by the nature and concentration of coal tar xenobiotic organic matter (XOM) and other PAH molecules present in the medium under various physical states. The objective of the present study was to quantify the effects of these factors using batch experiments, in order to simulate naphthalene transport in soil–tar–water systems using column experiments. Naphthalene sorption was studied in the presence of (i) solid coal tar particles, (ii) phenanthrene supplied as pure crystals, in the aqueous solution or already sorbed onto the soil, (iii) fluoranthene as pure crystals, and (iv) an aqueous solution of organic molecules extracted from a liquid tar. All experiments were conducted under abiotic conditions using short naphthalene/sorbent contact times of 24–60 h. Although these tests do not reflect true equilibrium conditions which usually take more time to establish, they were used to segregate relatively rapid sorption phenomena (“pseudo equilibrium”) from slow sorption and other aging phenomena. For longer contact times, published data have shown that experimental biases due to progressive changes in the characteristics of the soil and the solution may drastically modify the affinity of the solutes for the soil. Slow diffusion in the microporosity and in dense organic phases may also become significant over the long term, along with some irreversible aging phenomena which have not been addressed in this work. Results showed that PAHs had no effect on naphthalene sorption when present in the aqueous solution or as pure crystals, due to their low solubility in water. Adsorbed phenanthrene was found to reduce naphthalene adsorption only when present at relatively high concentrations (about 120 mg/kg) in the soil. In contrast, experiments carried out with coal tar particles revealed a significant effect. Naphthalene sorption appeared to be proportional to the amount of coal tar added to the sand or soil, and a much higher affinity of naphthalene for XOM (Koc above 2000 cm3/g) than SOM (Koc around 300 cm3/g) was observed. Naphthalene transport in the columns of sand or soil spiked with coal tar particles was simulated very satisfactorily with a dual double-domain model. Around 90% of naphthalene retention by coal tar was found to occur within the organic phase, suggesting a phase partition process which may be explained by the amorphous nature of the XOM and its extreme affinity for naphthalene. For SOM, however, which is present as porous microaggregates of clay and humic substances, with less affinity for naphthalene, only 1/3 of naphthalene retention was found to occur within the organic phase, underlining the significant role of surface adsorption in the short term behavior of naphthalene in soil. For longer contact times, the model simulations proposed in the present study should be coupled to slow sorption, aging and biodegradation models to describe long-term behavior of naphthalene in soil–tar–water systems.

The adsorption-desorption of naphthalene on several soil fractions and model soils has been studied in batch and column experiments to investigate the complementarity between the two methods. Batch experiments, in which the sorbents were suspended in aqueous solutions of naphthalene at different initial concentrations, were used to determine the states of apparent equilibrium and approach the kinetics of adsorption and desorption. Apparent equilibrium was reached in batch within 10 to 15 h and could be described with simple linear isotherms in the ranges of concentrations studied. A significant fraction of naphthalene was found to be adsorbed almost instantaneously, the rest being adsorbed more progressively, following first-order kinetics. Adsorption of naphthalene mainly takes place on the organic matter of the soils or soil fractions. Adsorption is directly related to the organic content of the soil fractions and not to the size of the particles with which the organic matter is associated. Naphthalene adsorption was found to be well reversible when the pollutant-sorbent contact time was short (24 h) and the sorbed concentration was relatively low. At higher sorbed concentrations, a slight hysteresis effect was observed in batch studies. Data obtained from soil column experiments conducted with water as mobile phase were in good agreement with the results obtained in batch. The adsorption was described using a double-compartment model, considering a nonuniform distribution of the adsorption sites (organic matter) between the external surface of soil microaggregates (with instantaneous adsorption) and the internal compartment inside the microaggregates (with rate-limited adsorption). The site distribution depends on the nature and degree of humification of the soil organic matter.

Publisher Summary This chapter focuses on a systematic study of mixtures of the hydrocarbon–supercritical carbondioxide type to develop a single all-purpose model for solid–fluid and liquid–fluid equilibria. The chapter describes an “excess function–equation of state” model with an intermolecular interaction parameter. The interaction parameter is correlated with the parameters of interaction between the groups constituting the molecules and the fractions of sites occupied by these groups. The variation of the interaction parameter according to temperature is determined. The model is based on the relation between the excess Helmholtz energy of the mixture and the equations of state of its components. The excess Helmholtz energy is calculated in Guggenheim's quasi-reticular theory. The group contribution method is developed from experimental data concerning solid–fluid and liquid–fluid equilibria for a large number of hydrocarbons. The modelization of solid–fluid equilibria by a predictive method is more difficult because of the structural complexity of compounds of low volatility.

The aim of this work is to characterize the flocculation process of a bentonite synthetic suspension with characteristics close to Bega River from Timisoara, Romania. The time stability of the synthetic suspension was firstly investigated. After a few days of continuous mixing a stable suspension was reached, stability being confirmed by monitoring the main physicochemical parameters (pH, temperature, turbidity, dissolved organic carbon and initial particle size). In order to determine the optimum dose of coagulant, the stable suspension was subjected to jar-test experiments using different doses of alum (5 - 35 mg.L-1). For a suspension with initial turbidity

International audience