Paramètres de détermination de la stabilité des déchets. Comparaison de différents modes de gestion des déchets non dangereux

National audienceLes déchets non dangereux, déchets ménagers et déchets industriels banals, sont généralement incinérés ou enfouis en centres de stockage anciennement dits de " classe II ". La gestion de ces centres de stockage répond à des critères très précis, tant au cours de l'exploitation qu'après l'arrêt de celle-ci. En particulier, un suivi des sites fermés est imposé pendant 30 ans, période pendant laquelle la matière organique, contenue dans les déchets, produit par dégradation biologique d'importantes quantités de biogaz et des lixiviats chargés. A côté de ce mode de stockage " classique ", il est apparu depuis quelques années des modes de gestion différents, qui visent à limiter les émissions gazeuses et liquides des déchets enfouis. Il s'agit d'une part, du fonctionnement de CSD en casiers de type bioréacteur, et d'autre part de l'enfouissement de déchets pré-traités biologiquement. A ces nouveaux modes de gestion s'ajoutent le tri en amont avec les collectes sélectives, et un traitement mécanique plus ou moins poussé avant le traitement biologique, permettant de diminuer la part de produits recyclables ou inertes, de rendre plus accessible la matière organique contenue dans les déchets, et d'homogénéiser la matrice

Risk assessment and comparison of short-term and long-term emissions for different treatment and disposal phases of MSW

International audienceA research program including a comparison between short term and long term emissions of MSW landfill started in 2006. The goal of that program was to access the human health chronic risk of three different waste disposal processes (anaerobic with/without leachate recirculation, with/without aerobic pretreatment) and to provide new criteria for the disposal site. A methodological approach using both calibration of the short term fluxes by in situ measurements and the prediction of long term fluxes by the use of exponential decreasing functions was explored. The identification of contaminant species was made by qualitative and quantitative concentration measurements done in a first stage on the landfill gas, and the collection of chemical leachate load measurements. At this stage of the study, the work did not show specific chemical contaminant species for the different waste disposal

L'oxydation du biogaz : un moyen de réduire les émissions résiduelles

National audienceDepuis le début des années 2000, plusieurs facteurs concourent au besoin de développement de nouveaux modes de gestion des déchets municipaux. Parmi ces nouveaux modes de gestion, la filière de traitement mécanobiologique (TMB) permet de réduire très significativement les émissions résiduelles de biogaz. Les émissions de carbone sous forme de biogaz constituent en effet la très grande majorité des émissions de carbone des déchets enfouis, quelque soit la filière retenue (filière conventionnelle, bioréacteur, TMB)

Quality of composts from municipal biodegradable waste of different origins

International audienceMechanical biological treatment of municipal solid waste is increasing rapidly inaFrance as well as in other European countries. One of the outputs of this treatment is a compost prepared from the organic matter of the waste. This organic matter can be either collected selectively from the customers as biowaste, or separated from the total MSW in the plant. Unlike in Germany or Austria, where only the compost from selective collection of biowaste is allowed to serve as an amendment, in France the use of the compost is based on its compliance to a quality Standard. We present here the first results on an enquiry concerning the quality of composts from the two processes, determined on 5 French plants, between 2008 and now. All the composts fulfill to the prescriptions of the Standard and can be used as soil amendments

Lateral landfill gas migration : characterization and preliminary modeling results

International audienceLateral landfill gas migration occurs in the surroundings of a MSW landfill with capped old waste cells. Three areas were identified by poor vegetation growth. Methane flux chamber measures confirm the extent of these areas, as observed in the cultivated land. These measures and some complementary physical measures were used to build a conceptual model of lateral landfill gas migration in the geological layer. Prior to drilling new boreholes on the site, a preliminary simplified model will be built with the numerical code TOUGH2-LGM. A description of the geological units, methane flux and the results of the preliminary modeling are presented. The aim of this work is to identify the key parameters used to predict the travel distance of landfill gas

Case study of sulphur compounds emissions characterization

International audienceIn order to manage the methane and sulphur compounds emissions of a landfill area with deposits of plasterworks, a flux measurements study was conducted with a mobile laboratory, portable analysers and different chambers. The static chamber was first used in order to locate the methane hot spots. The funnel and the Total Reduced Sulphur (TRS) analyser allow the comparison between emissions of methane and hydrogen sulphide which represent the predominant sulphur compound. In a second stage, the variability of the hydrogen sulphide emissions was monitored with two dynamic chambers and a period of several days. Hydrogen sulphide emissions by cap are much lower than those predicted by the methane flux and the concentration of hydrogen sulphide in landfill gas (LFG)

Determination of guidance values for closed landfill gas emissions

International audienceIn order to promote active landfill gas collection and treatment or natural attenuation, it is necessary to identify trigger values concerning landfill gas emissions in the preliminary stage of a risk assessment. The determination of these values is the first goal of a work which includes a large regulation review and the study of a generic inhalation exposure scenario for the most common reuse of French Municipal Solid Waste (MSW) landfill surface, namely a recreational area without residential buildings. The health risk levels of this scenario are lower than the usual levels and enable to determine trigger values for methane production rate. These results and the methane oxidation rate in the landfill cover allow for the determination of residual methane surface emission rates. The combination of these parameters with on-site specific measurements enables the promotion of natural attenuation or active landfill gas treatment

Percolation parameter and percolation-threshold estimates for 3D random ellipses with widely-scattered distributions of eccentricity and size

In fractured materials of very low matrix permeability, fracture connectivity is the first-order determinant of the occurrence of flow. For systems having a narrow distribution of object sizes (short-range percolation), a first-order percolation criterion is given by the total excluded volume that is almost constant at threshold. In the case of fractured media, recent observations have demonstrated that the fracture-length distribution is extremely large. Because of this widely-scattered fracture-length distribution, the classical expression of the total excluded volume is no longer scale invariant at the percolation threshold and has no finite limit for infinitely large systems. Thus, the classical estimation method of the percolation threshold established in short-range percolation becomes useless for the connectivity determination of fractured media. In this study, we derive a new expression of the total excluded volume that remains scale invariant at the percolation threshold and that can thus be used as the proper control parameter, called parameter of percolation in percolation theory. We show that the scale-invariant expression of the total excluded volume is the geometrical union normalized by the system volume rather than the summation of the mutual excluded volumes normalized by the system volume

Estimating methane emission and oxidation from two temporary covers on landfilled MBT treated waste

International audienceSurface gaseous emissions and upper layer waste gas composition were measured on two French MBT plants with aerobic pre-treatment process. The goals were to characterize the gaseous emissions, and to assess the efficiency of the upper layer to oxidize the methane flux coming from the residual organic fraction. The first plant was operated without recovery of organic fraction and with concentration of the fine fraction in a cell. The methane fluxes were high and the oxidized methane fraction was moderate (40%) for selected point measurements. On the contrary, the second plant organic fraction was recovered. The residual methane emissions were low with a high fraction of oxidized methane (up to 80%). These results were obtained with favourable humidity and temperature condition

Measurement of persistent organic pollutants in landfill leachates

International audienceLeachates from two landfills which receive the stabilized waste (site A) and sorting refuses (site B) from mechanical biological treatment plants (MBT) have been sampled. Classical parameters, as well as organic persistent pollutants (POPs) have been measured and compared between the two sites, and to data from litterature (classical parameters and POPs) and to limit values for drinking waters, when applicable, for POPs. Though the study was limited to 3 samples, the concentrations in organic micropollutants varied, depending on the compounds and on the treatment process