| Environnement, ingénierie & développement |  |
N°12 - 4ème Trimestre 1998
1. Éditorial n°12 Déchets Sciences et Techniques: « Les raisons de la complexité »
Une part significative de la recherche sur les déchets concerne les filières de traitement et leur impact (réel ou potentiel) sur l'environnement. Cette évaluation des impacts, associée au bilan énergétique des procédés et à la contribution à l'épuise ment des ressources naturelles constitue un élément de premier ordre dans le domaine de l'aide à la décision en matière de choix de filière. On observe, à partir des travaux réalisés sur ce sujet un accroissement significatif des niveaux de complexité de cette approche et ce pour quatre raisons essentielles :
2. Qu’est-ce qu'un déchet ? Le droit européen rejette l’acception économique
From an economic viewpoint a waste is mainly defined in relationship with market value; but the Brussels' authorities are anxious to control as far as possible and they reject this criterium. The suggestion is that the administrative control on waste (from the Brussels' meaning) has to be applied solely on waste from an economic meaning.
3. La modernisation des systèmes de gestion des déchets ménagers: Coûts de gestion, aides à l’emploi et solvabilité des activités
This article follows up the presentation on employment accounting methodology concerning household waste management, and demonstrates that it is the increase in the valorization substance rate that creates employment in the field of household waste management. The study based on a fictive territory of 100,000 inhabitants, here incorporates exploitation costs including the cost of labor. The modernization of waste management systems leads to additional financial expenses for the collectivity. Using a theoretical support calculated by means of a standard market parameter basis, we then introduced complementary hypotheses regarding employment statute and subsidized employment positions. The macro-economic conclusion of this hypothetical study has not been calculated due to the fact that several methodological unknowns can have a bearing on this type of exercise. The approach consists of relating employment creation to the cost for the principal participants: the users, the service operators (either public or private) and the national collectivity. ln order to evaluate the repercussions on the solvency of the operations, the aid and specific subsidies in the household waste sector (FMGD support, Eco-packaging) and the grants and employment subsidies are incorporated at the very end. The test indicates that employment subsidies tend to have a share almost as great as the activation of the Polluter Payer Policy in the financing of waste policies, especially the technical steps […]
4. Remobilisation de métaux lourds à partir de déchets solides vitrifiés: Nouvelles techniques d'évaluation
New techniques for the investigation of the diffusion of metallic pollutants from solid wastes are presented. The methodology is based on the use of dynamic leaching tests with on line detection by ICP-MS and transmission electronic microscopy.
5. Métaux lourds et incinération de déchets industriels : Localisation et spéciation dans les cendres volantes et les mâchefers
The emission of heavy metals from waste combustion devices is a potential threat to human health. This study concerns the behaviour of some heavy metals in terms of partitioning and speciation during the combustion of a model of industrial waste in the conditions of incineration. The elements studied were Ca, Ba, K, Na, Cd, Cr, Cu, Sn, Pb, Fe, Ni, Zn and Cl. Sawdust containing solvents and heavy metals was burnt at 850 °C and 1 050°C in a pilot fixed bed (27kW, 1 kg/h). Solid effluents (residual and fly ashes) were acid digested and analyzed by ICP-MS to quantify each element in the phases and the partitioning of the elements was calculated. In order to determine some informations in terms of speciation, techniques as X-ray powder diffraction and X-ray microanalysis were used for fly ash. Residual and fly ashes are principally constituted of BaSO4, SiO2, TiO2, CaO, CaSiO3 and BaTi8O16. Traces of metallic oxides (Fe2O3, Pb2O3 and Pb3O4) were also found. Leaching tests in water of the solid effluents gave a very low soluble fraction which contained chorides, sulfates and bromides associated to metals like calcium, sodium, potassium, cadmium, zinc, manganese, chromium and lead.
6. Analogie entre un mâchefer issu de l’incinération de déchets industriels et des roches ignées : Application à l’étude de la lixiviation
The analogy between slag that is producted during incineration of industrial wastes, and igneous rocks allow to approach the physical, chemical mechanisms of Cr, Cu solubility and Pb, Zn insolubility during leaching. pH is an important parameter because the métals behaviours depend on it. It varies with relative quantity of aluminium in regard of sodium of slag, and with sulfite transformation into sulfat. Most of the chromium is inside the magnetite, so quantity of solubilized Cr is small.
7. Application d'une méthodologie d’évaluation des procédés de stabilisation/solidification à base de liants hydrauliques
The evolution of the legislation concerning hazardous waste landfilling has induced many laboratory studies on the stabilization and the solidification of these waste. Thus a lot of processes have been developed; many are based on stabilization/solidification by hydraulic binders and are exploited by manufacturers. The development of these processes requires a phase of evaluation. In this context, Ademe has asked Polden-Insavalor to define a protocol of evaluation of stabilization/solidification processes using hydraulic binders. One treatment process based on hydraulic binder has been developed, applied on two industrial wastes, a used catalyst and an activated charcoal and tested. This study is devoted to the evaluation of this process, by tests inspired of the Ademe's protocol. First, we propose theoretical and practical modifications to the Ademe's protocol especially the points considering the water absorption capability of treated waste, their sensitivity to external agents and the study of their average-term behavior during leaching.Second, over the critical analysis, the study proposes a concrete and simple methodology of evaluation of the stabilization of a waste in four steps. The first provides a method to realize a material balance of the treatment. It is thus possible to verify if chemical elements of reagents are fully found in the treated waste and to conclude as for the absence of pollution transfer during the treatment. The second step is about the […]
8. Comparaison interlaboratoire de résultats d'analyse des hydrocarbures aromatiques polycycliques dans un sol
In order to understand the analytical difficulties to determine polycyclic aromatic hydrocarbons (PAHs) in a contaminated soil, nine laboratories compared the PAHs contents of the 16 US-EPA list, in a soil coming from a former cookery site, and in the solvent extract. The results show that:- the analytical protocols are very heterogeneous (nine laboratories and nine analytical methods),- Soxhlet, Soxtec and ASE extraction methods lead to comparable results,- Gas chromatography - GC - allows more reproducible results (20% of variation) than liquid chromatography - HPLC - (between 20 and 80%), even if both techniques lead to comparable concentration levels,- the gas chromatography and the liquid chromatography responses seem independent of the molecular weight of the compounds, and rather related to the content levels: the more the content is increasing, the more the variation rate is decreasing. A subsequent study will focus on the influence of the pre-treatment on the measured values.