| Environnement, ingénierie & développement |  |
N°25 - 1er Trimestre 2002
1. Du concept à l’application de la mesure environnementale non paramétrique: Exemple de l’étude d’un réseau d’assainissement industriel
A complementary approach of environmental analytical chemistry is presented in this paper. The non parametric measurement (NPM) concept is based on the direct exploitation of an analytical signal (absorbance, intensity, potential, …) without parameter calculation, leading to the simple characterisation of the studied sample. For example, the existence of a direct isosbestic point for a set of absorption spectra (point where spectra cross together) shows that the global quality of the medium is conserved and is in equilibrium between two given states (without considering non absorbing species). From the calculation of the ratio of (1) the number of spectra crossing at a given isosbestic point, on (2) the total number of spectra, the global quality variability can be simply estimated, without any knowledge of the medium composition. After the explanation of the NPM concept, the study of an industrial wastewater network in a refinery site is presented. Starting from the sampling of wastewater along a network branch, the calculation of variability is carried out with the study of isosbestic points after normalisation (in order to take the dilution effect into account). The examination of UV spectra shape brings complementary qualitative information. Moreover, the quantitative exploitation of spectra is obviously possible, namely by the use of a deconvolution method. Limiting the application to the results of NPM, the study shows that the global variability decreases from the […]
2. Kit de diagnostic rapide de la contamination des sols par les HAP: Principe, mise en œuvre et évaluation
Investigation of contaminated soils, assessment of treatment processes and environmental monitoring of remediated soils require screening many samples. Laboratory analyses (gaz or liquid chromatography) are expensive and time consuming. Moreover, the procedures are not suited to field conditions. In this context, a new field kit for PAH diagnosis has been developed. Based on the UV spectrophotometric analysis of a soil organic extract, the total PAH estimation, in reference to the 16 PAHs included in the US Environmental Protection Agency Priority Pollutants List, can be obtained on site within 20 minutes. Moreover, a “treatability index”, informing on the potential degradation of pollutants which may occur into the soil, is given. This last is connected with the proportion of PAH including two or three cycles in their structure (“light PAHs”) which are known to be more readily biodegradable. A validation on several contaminated soil samples, from different origins, has been carried out.This tool allows to give a rapid diagnosis of total PAHs concentration in a contaminated soil and to point out the most polluted areas on an industrial site. The proposed kit is well fitted for the monitoring of a treatment process and the survey of natural attenuation into a PAH contaminated soil.
3. Étude d’une voie de valorisation des mélanges PE/PP et PE/PS: Aspect rhéologique
The aim of this article is to investigate the effectiveness of commercial compatibilizers for two kinds of virgin plastic mixtures, high density polyethylene (HDPE)/ polypropylene (PP) and HDPE/polystyrene (PS) blends, in order to gain insight into the recycling of wastes from those frequently encountered mixed plastics. Blends were made using a single-screw extruder to follow an industrial-convenient process. Morphology and melt-rheological properties of several blends (compatibilized and not compatibilized) was studied. When compatibilized, blends present better dispersions: the size of the dispersed particles decreases, the shape of these particles is generally spherical, size-distribution is reduced and interfacial adhesion is better. Study of meltrheological properties enabled us to confirm compatibilizer’s effect and to specify the contributions of partial miscibility, especially for not compatibilized PE/PP blends.
4. Évaluation d’une filière simplifiée de compostage des ordures ménagères
The concept of organic matter recovery for use in agriculture is attracting a great deal of attention. In Morocco, municipal solid waste contains large amounts of organic matter nevertheless, the composting facilities have some problems due to the high waste moisture level and to endproduct quality. A simplified composting system is experimented in a plant recently built in Agadir. Analytical results of ten samples taken from ten windrows of compost, which are 10 to 15 months, show some improvements of end-product aspects, however the presence of physical contaminants and the high soluble salt content limit its applications in agriculture.
5. Déchets et archéologie
Archeology is only one of the sciences of waste and is itself partially a science of waste.The marks of the waste provide information :• on the one hand on the conditions and ways of life,• on the other hand, more particularly, on waste management in the past.Differential conservation of the materials, whichdepends on the substance and its environment, maymislead the discover on intensity of their use.Fortunately progress of equipment and analysismethods make feasible the identification of tinyand unsuspected marks.For a better knowledge of the life during fast past,the works of Cuvier (which are related to anatomy,paleontology and biostratigraphy) are important.The paleolithic is characterized by cutting of flint. A. Leroi-Gourhan has shown that a meticulous examination of the “negatives” of useful parts draw many lessons. From paleolithic to iron age, slagbrings information too, and J. Barrau puts emphasison early ecological practices.On another hand, archeology brings information onwaste management, including prevention: wastefrom buildings (ruins), bodies (human remains),conservation of written works and reuse of thematerial (support), industrial scrap, waste fromcommercial and administrative activities, wastefrom households, including marks from organic fermentesciblematerials (biowaste).However practices of reuse and recycling have destroyedsome interesting remnants and may misleadconcerning datation and interpretation.
6. Éditorial n°25 Déchets Sciences et Techniques: Le développement durable : question de risques ?
A la demande du gouvernement, l’Académie des Sciences a mis en place un comité d’experts pour établir un rapport sur l’état de la science et de la technologie en France. Onze rapports ont été élaborés, ainsi qu’une synthèse, objet d’un douzième volume. Cet ensemble brosse un panorama détaillé des moyens mis en œuvre dans des domaines de la recherche et du développement à forts enjeux économiques et sociaux. Une de ces études concerne le thème des « Matériaux du nucléaire ». Le développement de la filière électronucléaire a dès ses origines impliqué en France un important effort de recherche dans ce domaine. En effet la sûreté des installations et de la gestion des matières radioactives demande une extrême fiabilité des propriétés des nombreux matériaux mis en œuvre et soumis à des conditions exceptionnelles. Le rapport récemment publié (RST n° 5, Académie des Sciences, Editions Tec & Doc, www.tec-et-doc.com) aborde les problématiques posées par les matériaux aux différentes échelles : compréhension des mécanismes élémentaires à l’échelle microscopique, maîtrise du devenir à très long terme des déchets radioactifs, organisation du démantèlement des centrales en fin de vie qui sont autant d’enjeux qui ont demandé et demandent encore la mobilisation de la communauté scientifique. Les conclusions du rapport amènent à des recommandations pour la mise en œuvre d’une politique de la recherche capable […]
7. Caractérisation expérimentale de l’émission d’oxydes d’azote dans l’incinération des déchets ménagers en four à grilles
In front of a deposit of waste in constant evolution, the incineration became a very interesting alternative within the fields of management of waste. Nevertheless the combustion is generative of polluting, notably gas among whom nitrogen oxides. The study of the mechanisms of formation of these species shows a very strong dependence of their yield face to face of the local level in oxygen. So, our study was led to determine the influence of the excess air on the formation of NOx during the incineration of municipal solid wastes. This study allows to note the importance of the distribution of the airs between the primary and secondary injections.