| Environnement, ingénierie & développement |  |
N°30 - 2ème Trimestre 2003
1. Éditorial n°30 Déchets Sciences et Techniques
La problématique du développement durable est devenue si populaire qu’il est urgent de la préciser et de la rendre opérationnelle. Pour cela, le plus simple est de se référer à un schéma à trois pôles : nature, économie-technologie, société1. La plupart des études se contentent d’examiner un pôle et les flux qui s’y rattachent ; c’est le cas des études environnementales, centrées sur le pôle nature. Une étude labellisée développement durable, au contraire, s’intéressera aux trois pôles, et à la boucle qu’ils forment.Bien entendu, de telles études sont beaucoup trop complexes et on se contente alors d’une approche réductionniste consistant à isoler un sous-système et ses flux, tout en évaluant aussi justement que possible le biais introduit par cette réduction. Il s’agit alors de choisir une échelle, c’est à dire d’isoler un petit « canton » de l’espace-temps, en considérant que le fait de l’isoler ne prive pas l’étude de sa signification. Cette question n’est pas triviale surtout lorsque les phénomènes en cause appartiennent à des pôles différents.Définir un système (qu’il soit aquatique, urbain, ou industriel) conduit donc à traiter de problèmes à plusieurs compartiments, ce qui signifie en fait, représenter de façon satisfaisante une famille de processus très dissemblables et néanmoins fortement couplés. Il faut remarquer que l’échelle d’observation en temps et en espace est largement […]
2. Le coût social des consommations d’espace: Approche méthodologique et étude de cas relative au traitement des déchets
Among natural resources, space or land has some specificity. In the frame of Life Cycle Analysis (LCA), authors are considering this resource, but most of them are contenting with indicating the quantity of space which is occupied by an activity. However some authors have developed analysis on this theme by considering the various environmental impacts which are related to land (particularly soil) uses. The objective of this paper is different, that is to say to evaluate the social cost of space consumption (and not to describe and analyse the various environmental impacts). Moreover a stake is to bridge a gap between LCA and economic analysis. Land generates private and social benefits; but this means that space savings, for a similar function or a same utility, is generating a social benefit. The different kinds of land or space have not the same interest (the same value) for the community. Then inthe frame of LCA, it appears preferable to take intoaccount the land value, and not only the land surface (quantity). This value is related to use and exchange (market) values, rent or buy, and possibly to specific preferences of the community. In the frame of LCA, economic valuation (monetarization) of land consumption will facilitate the aggregation of various environmental impacts (if they are monetary valued too). What is called commonly “space consumption” is generally a temporary use for some activity. However change of “intrinsic" attributes and land value may […]
3. : Cas de la décharge d'ordures ménagères d'Etueffont (France)
In the Etueffont landfill (Belfort, France), leachates product were treated by stabilisation ponds (4 basins). In order to ameliorate this process, two sand filters were installed in the upstream of the first basin. An analytical follow-up of physical and chemical parameters (major elements, metals and organics with AOX, AGV and atrazine) were carried out in the leachate, on the outlet side of the sand filters and in the treated leachate of the station at the end of lagooning. The results pointed out a short variations of physicochemical composition in the leachate between 2000 and 2001, most likely due to the maturation of the fill and a very significant removal of SM was observed due to the gravel filters which reflects for all the followed parameters. The physical and chemical reaction of the filter sand is detailed and also the efficiency of the natural lagooning on wastes fluids from landfill.
4. Contribution à l’évaluation de l’impact sur les écosystèmes aquatiques de la valorisation en BTP de mâchefers d’incinération d’ordures ménagères (MIOM)
Our project takes place in a sustainable development programme on the utilization of Thermic Process Residues in civil engineering concrete. The aim of this project is to assess the effect on the aquatic environment of the use of MSWI bottom ash in road base material scenario. To assess the risk for the ecosystems sumitted to MSWI bottom ash leachates, we have chosen to work with unicellular algae. Microalgae play an important role in the equilibrium of aquatic ecosystem, being the first level of the trophic chain to produce organic matter and oxygen. Our bioassays are specific to a metabolic way. They allow the detection of early disturbance in organisms, which can generate more important disturbances. We test the enzymatic alkaline phosphatase activitiy (APA) of Chlorella vulgaris. In the same way, we achieved some normalized algal growth tests which concern the global metabolism of algae. We have tested MSWI bottom ash leachates from standart collection and from selective collection. The results showed an alkaline phosphatase decrease and an algal growth inhibition. APA displayed the presence of heavy metals in leachates. Some experiments conducted in the laboratory showed that APA of Chlorella vulgaris is disturbed by the presence of heavy metals. These tests showed that APA decrease is more important in case of standard collection than in case of selective collection. This project will contribute to define Thermic Process Residues enhancement conditions. Development of […]
5. Les procédés de gazéification comme alternative pour la valorisation de boues de stations d'épuration des eaux usées
The problem of wastewater treatment plant sewage sludge is becoming crucial. Indeed the quantity of sewage sludge will increase with the population and the economic developments, the rise of the number of treatment plants and their better performance. Sewage sludge treatment is at the moment realized in limited ways. Whatever the future of those ways and without creating polemics, they will not be able, to absorb this increasing volume. It consequently becomes necessary to diversify the methods of treatment to answer the problems arising from the management of this waste. Within this framework, the new thermochemical ways of treatment by valorization seems more interesting. Indeed, they present in addition to the advantage of the possibility of processing, the capacity to easily produce "storable" and valuable compounds. Thus will treat, in this article, the interest to develop the processes of gasification of waste water sewage sludge.
6. Traitement d’un effluent industriel fluoré
The characterization of the industrial effluent has been carried out. This wastewater is strongly acid, salty, hard and concentrated mainly in fluorides, orthophosphates, sulfates and in metal compounds. The treatment of this effluent, mainly the defluoridation was realized by coagulation-decantation. This technique consists in precipitating fluorides, by using lime and calcite. The physico-chemical parameters that influence the treatment have been studied. The results show that it is possible to eliminate more than 85% of fluorides, 84% of orthophosphates, 45% of sulfates, 90% of Cd, 77% of the Co, 93% of Cu, 96% of Fe, 99% of Pb and 99% of Zn.
7. Dégradation et potentiel polluant d'un produit phytosanitaire : l'atrazine
Only a low percentage of the pesticide sprayed on a culture has a direct biocide action. The major part remains in the soil as extractable or non-extractable residues, like the parent product form or as degradation products. As a consequence, pesticide degradation study in soil is of great interest to assess its environmental impact. For example, concerning the most famous pesticide, atrazine, degradation kinetics seem highly variable depending on climate and soil characteristics. In order to clarify this point, atrazine degradation has been studied in two opposite pedoclimatical situations: oceanic or semi-continental climate, with different past treatments (no repeated atrazine treatment or 17 years atrazine treatment). Our data show biological degradation of atrazine in both cases but significant differences appear between the two cases. In the one hand (soil with repeated treatments), a high mineralization of the molecule occurs (up to 70 % of the applied amount in 4 months). In the other hand, mineralization is lower with only 15 % of the applied atrazine mineralized after 4 months. Consequently, less atrazine residues are available to leach in the first case and this can limit the underground water pollution. This situation shows that repeated use of one pesticide on the same field can lead to an adaptation phenomenon which reduces water pollution potential. This case is favourable for environment provided agricultural efficiency of the pesticide remains.
8. Etude de l’affaissement et des performances d’un béton recyclé
Managing the building wastes is a recent challenge to which are confronted engineers, because only ultimate wastes will be stored in confined disposals. Valorisation of demolished concrete, without treatment neither major pollution risks, in the manufacture of new concrete, constitutes the first part of this work. Concrete aggregates from demolished structures are mainly re-used for road construction. Other reuses of concrete aggregates are possible such as the manufacturing of new concrete materials with good mechanical characteristics. Many investigators have been carried out in the world and comparisons between recycled concrete aggregate and conventional concrete have given different conclusions by the researchers. Sometimes it is different to compare some experimental results due to the lake of knowledge links to the composition of the recycled concrete. It is clear that the unconfined compressive strength Fc, the elasticity modulus E or the durability of the concrete are depending on the concrete composition through gravel on sand ratio G/S and water on cement ratio E/C relationships. Hence the substitution of aggregates method and the composition are clearly given. Experimental results issued from more than 100 cylindrical concrete samples are analyzed.