La biodiversité "aménage-t-elle" les territoires ? : vers une écologisation des territoires

Formé il y a moins de 30 ans, le mot « biodiversité » s’est rapidement diffusé et s’est récemment substitué aux termes plus usuels que sont la nature ou les espaces naturels. Ainsi que l’ont souligné Pascal Marty, Franck-Dominique Vivien, Jacques Lepart et Raphaël Larrère (2005), dans leur ouvrage « Les biodiversités : objets, théories, pratiques », le mot « biodiversité » dépasse désormais largement le champ de l’écologie auquel il fait référence et est mobilisé dans de nombreux débats, que ..

Caractérisation des sous-produits d'oxydation des boues en conditions sous-critiques et supercritiques

L'élimination de la matière organique et la réduction de volume des boues peuvent être obtenues par incinération, par oxydation sous pression en milieu humide ("wet air oxidation") ou par combustion en eau supercritique ("supercritical water oxidation"). Une étude en autoclave agité a permis de comparer sur une même boue d'épuration les performances des deux techniques d'oxydation voie humide et d'oxydation supercritique, en mettant l'accent sur les sous-produits résiduels en phase liquide et la composition de la phase gaz. Les résultats obtenus montrent que l'élimination de la DCO dépend fortement de la température: l'abattement de la DCO passe de 70 % à 235 °C à 94 % à 430 °C. L'azote organique de la boue est transformé en NH4+ mais seule une élimination limitée de l'azote totale est obtenue à 430 °C. Les sous-produits résiduels dans la phase liquide sont constitués en majorité d'acides gras, d'aldéhydes et de cétones, l'acide acétique étant prédominant. Hormis le CO2, les sous-produits gazeux majeurs formés par des réactions complexes comme la pyrolyse, le réformage et la méthanation sont CO, H2 et CH4. Dans les conditions supercritiques, tous les sous-produits gazeux sont fortement oxydés. L'augmentation de la température de traitement permet d'obtenir un résidu solide de plus en plus inerte, les cendres obtenues en conditions supercritiques contenant moins de 1 % de matière organique. Les performances des deux procédés étudiés laissent envisager leur développement à moyen terme comme voies alternatives d'élimination des boues.ContextAs the number of wastewater treatment plants increases, and the efficiency of treatment improves, the problem of how to dispose of the ever increasing amounts of generated sludge has intensified. For the beginning of the next century 1 million tons of sludge will be produced annually in France; disposal in landfills will be impossible and agricultural use could be limited by tight quality standards. Therefore, the development of effective and acceptable sludge processes is urgently needed.Destruction of organic matter in sludge and large reductions in sludge volume are achieved either by incineration or by wet air oxidation (WAO), which needs no fuel and generates no smoke, fly ash or emissions of NOx and SO2. Supercritical water oxidation (SCWO) offers an attractive alternative. Water, above its vapor-liquid critical point of 374°C and 221 bar, is an excellent solvent for organic compounds and becomes completely miscible with oxygen. Reported results of sewage sludge SCWO demonstrate rapid and effective treatment. The objective of this study was to compare sub- and supercritical water oxidation of sludge in terms of organic matter destruction and formation of by-products in both gas and liquid phases. MethodologyOxidation of sludge was studied in a 0.5 L batch reactor rated for 450°C-300 bar. The raw material was a biological sludge containing 4% solids with a chemical oxygen demand (COD) value of 52 g/L. In the standard experimental procedure, 100 mL sludge were heated up to reaction temperature and oxygen was then introduced in 50% excess with respect to COD. Heating was maintained during 1 hour before slow cooling to room temperature. The overall organic destruction was quantified in terms of total organic carbon (TOC) and COD. Gas and liquid phases sampled at room temperature after reaction were analyzed by gas chromatography (GC). Sulfur and nitrogen species were also analyzed.ResultsWhen the temperature increased from 210 to 383°C, COD destruction increased significantly (Table 1). At 383°C, a COD destruction efficiency of 94.3% was obtained. However, at 430°C, organic matter oxidation was only marginally improved. In WAO tests, considerable acetic acid was produced and remained in the substrate. The produced acetic acid was oxidized rapidly under SCWO conditions. Surprisingly, the concentrations of the other volatile fatty acids (VFA) remained approximately constant between 310 and 430°C (Table 2). In addition to VFA, which represent ca. 50% of the residual COD, oxygenated organic compounds such as aldehydes, ketones and alcohols were produced (Table 3). The data in Table 4 show that decomposition of organic nitrogen compounds into ammonia was completed at 383°C, while nitrates were reduced to N2 by reaction with organic matter and ammonia. NOx were not detected in the gas phase. The low reactivity of ammonia in supercritical water had been previously demonstrated. At 430°C, ammonia removal from sludge was limited to 15%. On the other hand, even in WAO conditions all sulfur species were totally converted to sulfate. Under subcritical conditions, the gas phase contained significant concentrations of hydrogen and carbon monoxide in addition to water, residual oxygen and carbon dioxide. Traces of methane and C2-C3 hydrocarbons were also detected (Figs. 1 and 2). These gases result from a complex chemistry including pyrolysis, steam reforming and water-gas shift. Under supercritical conditions, all these compounds were extensively eliminated by oxidation. Under supercritical conditions the residual solids contained less than 1% organic matter. By X-ray diffraction hydroxyapatite, quartz and kaliophilite were identified in the residual solids.These results confirm that supercritical water oxidation is a new sludge treatment concept of great interest. The degree of conversion of organic carbon is high, while liquid and especially gaseous by- products are produced in minor amounts compared to subcritical conditions. Temperatures higher than 430°C would be needed for substantial nitrogen removal

Overcoming barriers to manufacturing digitalization:Policies across EU countries

The digital transformation of manufacturing activities is expected to bring large societal benefits in terms of productivity and sustainability. However, uptake of digital technologies is slower than desirable. As a result, governments are taking action to try to overcome some of the barriers to adoption. However, the mechanisms through which government may act are quite diverse. In this paper, we compare the national strategies across the 27 countries members of the European Union. We map each country's initiative to 14 barriers to the adoption of digital technologies in manufacturing observed in the literature. We observe that most institutional efforts focus on providing funding, developing new regulatory frameworks related to data privacy and security, and creating human capital. Some known barriers to adoption observed at the firm level, such as the lack of off-the-shelf solutions, or the need for retrofitting old equipment, are largely overlooked. We do not find any relationship between the number of initiatives proposed by each country, and the country's existing level of digitalization. We conclude by proposing several policy recommendations, as well as directions for future research

Developing Intensity-Duration-Frequency (IDF) Curves From Satellite-Based Precipitation: Methodology and Evaluation

Given the continuous advancement in the retrieval of precipitation from satellites, it is important to develop methods that incorporate satellite-based precipitation data sets in the design and planning of infrastructure. This is because in many regions around the world, in situ rainfall observations are sparse and have insufficient record length. A handful of studies examined the use of satellite-based precipitation to develop intensity-duration-frequency (IDF) curves; however, they have mostly focused on small spatial domains and relied on combining satellite-based with ground-based precipitation data sets. In this study, we explore this issue by providing a methodological framework with the potential to be applied in ungauged regions. This framework is based on accounting for the characteristics of satellite-based precipitation products, namely, adjustment of bias and transformation of areal to point rainfall. The latter method is based on previous studies on the reverse transformation (point to areal) commonly used to obtain catchment-scale IDF curves. The paper proceeds by applying this framework to develop IDF curves over the contiguous United States (CONUS); the data set used is Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks – Climate Data Record (PERSIANN-CDR). IDFs are then evaluated against National Oceanic and Atmospheric Administration (NOAA) Atlas 14 to provide a quantitative estimate of their accuracy. Results show that median errors are in the range of (17–22%), (6–12%), and (3–8%) for one-day, two-day and three-day IDFs, respectively, and return periods in the range (2–100) years. Furthermore, a considerable percentage of satellite-based IDFs lie within the confidence interval of NOAA Atlas 14

Supramolecular chemistry of helical foldamers at the solid-liquid interface: self-assembled monolayers and anion recognition

The synthesis of a redox-active helical foldamer and its immobilization onto a gold electrode are described. These large molecular architectures are grafted in a reproducible manner and provide foldamer-based self-assembled monolayers displaying recognition properties

La solidarité écologique : un nouveau concept pour une gestion intégrée des parcs nationaux et des territoires

Cet article propose une première exploration du nouveau concept de solidarité écologique introduit dans le droit de l'environnement lors de la réforme de la loi sur les parcs nationaux français en 2006. Nous montrons que ce concept polysémique, tirant les enseignements de l'application de la loi de 1960, se fonde sur la prise de conscience des interdépendances du vivant et une nouvelle vision de la conservation de la nature. La solidarité écologique permet d'asseoir un compromis pragmatique entre écocentrisme et anthropocentrisme. Fondée sur les évolutions conceptuelles de l'écologie de la conservation, la solidarité écologique se décline selon une typologie qui intègre les enjeux de l'hétérogénéité spatiotemporelle de la biodiversité. Elle donne sens à l'élaboration des réseaux écologiques nationaux et internationaux et à la gestion intégrée des territoires de la biodiversité. La mise en débat public de ses spécificités locales et des valeurs qui lui sont attachées est nécessaire afin d'assurer sa considération et sa préservation

Adenocarcinoma in Caroli's Disease Treated by Liver Transplantation

Caroli's disease is characterized by congenital cystic dilatation of the intrahepatic bile ducts. In 7% of casea a malignant tumor develops complicating the course of the disease