| Environnement, ingénierie & développement |  |
N°34 - 2ème Trimestre 2004
1. Éditorial n°34 Déchets Sciences et Techniques: Dioxines et polluants organiques persistants : risque à l’échelle locale et risque à l’échelle planétaire
En 2004, la pollution par les dioxines demeure un sujet de préoccupation majeure au sein de la société française. On peut identifier deux raisons essentielles pour expliquer cette situation. D’une part, le risque dioxines reste aujourd’hui souvent associé aux choix des modes de gestion des déchets (en particulier l’incinération) et se trouve ainsi lié à nos modes de consommation et donc à nos modes de vie. D’autre part, l’exposition des populations aux dioxines autour d’une source et les risques sanitaires associés restent, malgré la progression des connaissances scientifiques, très délicates à évaluer.Pour ce qui est de l’incinération de déchets, ce secteur constituait la source prépondérante dans les années 90 et demeure une source majeure en France (56 % des émissions recensées en 2002). Néanmoins, il paraît utile de rappeler qu’en 1998, un des sites industriels français émettant le plus de dioxines était un site de recyclage de métaux. Dès cette époque, la question des dioxines apparaissait plus complexe qu’une simple opposition entre incinération (« polluante ») et recyclage (« propre »). Par ailleurs, l’action des pouvoirs publics français vers les sources majeures (incinération et métallurgie) a permis une diminution très significative des émissions totales de dioxines, celles-ci passant de 1740 g TEQ /an en 1990 à 380 g TEQ /an en 2002. Durant cette période, les émissions provenant spécifiquement des […]
2. Approche méthodologique de l’évaluation des risques écotoxicologiques liés à la mise en dépôt sur sol de sédiments de dragage
The implementation of an ecological risk assessment framework is presented for dredged material deposits on soil closed to a canal and a groundwater, and tested with sediment samples from a French North-Eastern canal. This framework includes two steps: a screening risk assessment, based on contaminant concentrations, and a detailed risk assessment based on toxicity bioassays and column leaching tests. The tested framework includes three assumptions, which are related (a) to effects to plants (Lolium perenne L.), (b) effects to aquatic organisms (Escherichia coli, Chlorella vulgaris, Ceriodaphnia dubia, and Xenopus laevis) and (c) to groundwater contamination. Several exposure conditions were tested, including standardised bioassays. According to the specific tested sediments, the three assumptions were more or less discriminatory, soil and groundwater pollution being the most sensitives. The assessment procedure has to be improved on several aspects, particularly assessment endpoint design for risk to ecosystems (e.g.: integration of pollutants bioaccumulation), bioassays protocols and column leaching test design.
3. Caractérisation de la matière organique naturelle et de son évolution dans les sols et les sédiments à l'aide du couplage US/UV
Natural organic matter in soils and sediments is transformed mainly by biological processes which may have an impact on surface and groundwater quality. A global characterization of this organic matter is proposed with the use of UV-Visible spectrophotometry after selective solvent extraction. Studied samples are pine and leafy humus, peat and sediments coming from a marsh. Oxidation index and humification index, calculated from UV-Visible spectra exploitation, respectively A220nm / A280nm and A465nm / A665nm, allow to estimate the evolution level of organic matter by mineralization and/or humification.
4. Prélèvement, stockage intracellulaire et dégradation des hydrocarbures polycycliques aromatiques par un champignon tellurique : Fusarium solani
Polycyclic aromatic hydrocarbons (PAHs) are of great environmental concern due to their mutagenic and carcinogenic properties. Their persistence in ecosystems is due to their low water solubility which results in their binding to particulates in soils, sediments and atmosphere. Bioremediation represents the major route for the ecological recovery of PAHs contaminated sites. The aim of this work was to investigate the uptake and storage of benzo[a]pyrene by a non white-rot fungus, Fusarium solani, and to characterize, by cytological methods, the intracellular fluorescent vesicles observed when growing the fungus on synthetic medium in presence of benzo[a]pyrene. We have demonstrated that PAHs uptake into fungal hyphae was a passive phenomenon. Indeed, benzo[a]pyrène uptake and storage in Fusarium solani was not prevented at 4°C or in the presence of cytochrome oxidase inhibitor (sodium azide). The use of two cytoskeleton modulating drugs (colchicine or cytochalasin) suggested that microtubules and actine filaments were not involved in PAHs transport. Ultrastructural study showed that PAHs incorporation was not associated with specific structures. The use of Sudan III and Rhodamine B stainings showed that PAHs were accumulated in pre-existing structures corresponding to lipid vesicles. We found that Fusarium solani, was able to store into lipid vesicles and degrade efficiently a large scale of PAHs. The degradation rates were about 84, 70, 58, 34 and 40% for anthracene, […]
5. Phytoremédiation : influence des ligands naturels sur la mobilisation et l'accumulation de métaux par les plantes: Cas de plants de blé modifiés génétiquement
Phytoremediation is a remediation process that can be used to clean up soils contaminated with heavy metals. Three main approaches can be utilized: phytoextraction, phytovolatilization, and phytostabilization, each of them exploiting the natural ability of plants to accumulate or exclude/stabilize elements from soils. To implement this alternative technology, a better understanding of the various processes controlling metal mobilization, uptake and sequestration by plants is needed. Metal chelation is recognized as an important factor, regulating to a large extent metals solubility and availability to plants. Natural ion chelators (or MIL: Metal Ion Ligand), produced in the tissus or exuded by the roots, are involved in these phenomena, but their exact nature and the various mechanisms have to be précised. We investigated the influence of elevated metals concentrations on MIL profiles and on metal accumulation in the plant tissues in wheat (Triticum aestivum L.CV Chinese Spring) genetically modified by disomic addition of wheatgrass (Lophopyrum elogatum L.) chromosomes. Qualitative and quantitative determinations of MIL profiles are realised by GC-MS and RMN 1-D and 2-D. Concentrations of metals in the tissues are obtained by energy dispersive X-ray fluorescence spectroscopy. Correlations between some metals (ie, Fe, Zn, Mn) and some MIL exuded or present in the roots (ie, acetate), depending on the various genotypes, have been observed. The results suggest possible […]
6. Diagnostic maintenance d'une station d'épuration des eaux usées de papeterie
The installation under study is a water treatment plant used by the paper industry (Norampac Avot-Vallée, Pas-de-Calais, France). The aim is to develop an indicator which shows how well the installation is functioning and to create preventive maintenance schemes. First, an external and internal functional analysis and a Pareto analysis will be used to specify the critical points of the installation. Then a failure analysis will be completed using the FMEA method (Failure Mode and Effects Analysis). This method will permit us to elaborate on the details of the maintenance plans. Finally, an indicator of the treatment plant's efficiency will be proposed. This monthly computed indicator will link the treatment plant operation and the water output quality. It can be defined as a target to reach or as a low threshold. This work is a first step towards a more elaborate model which will allow us to optimize the treatment plant efficiency.
7. Réalisation d'un capteur à fibre optique infrarouge pour la détection des polluants dans les eaux usées
Infrared optical fibers based on chalcogenides are investigated to optimize their transmission in the infrared optical range and they are used for in situ detection of pollutant in groundwater. The pilot scale measurements proved that a Te2As3Se5 (TAS) glass fiber permits access to the absorption line positions of classic pollutants like tetrachloroethylene or dichlorobenzene. Moreover, it has been shown that the original design of the fiber enables detection of weak concentrations of pollutants down to 1 ppm. The experiments led in "real world" conditions proved that such a sensor is able to discriminate simultaneously several pollutants and permit to follow the general evolution of their concentration versus time. Finally, in the future, this technique could become an alternative method to the classical chromatography analyses, avoiding then the withdrawals.
8. Schéma de valorisation des grignons d'olives produits par les maâsras marocaines
In Morroco little olive mills called “maâra” release a great quantity of olive cake in environment after extracting olive oil because there is no regulation. The chemical composition of olive cake and the important quantity released lead to environmental pollution, not acceptable with respect to the principle of sustainable development. To remedy the problem we propose a valorisation flowsheet including production of glycerin as made in other countries, and production of furfural which Morocco imports to produce lubrication oil.