| Environnement, ingénierie & développement |  |
N°44 - Octobre-Novembre-Décembre 2006
1. Éditorial n°44 Déchets Sciences et Techniques: Concours de thèses « Déchets ». Un bilan encourageant et une deuxième édition en 2007
Les prix du concours de thèse organisé par la revue Déchets, Sciences et Techniques ont été remis à Lyon, dans le cadre de Pollutec. Les thèses présentées par les candidats (dont les résumés seront téléchargeables courant janvier sur www.pro-environnement.com) reflètent la très grande qualité des travaux réalisés. Elles se rangent dans un large spectre de champs disciplinaires : génie des procédés, chimie, microbiologie, droit, économie, gestion. Elles ont en général été réalisées en partenariat avec des acteurs socioéconomiques et beaucoup ont été soutenues par l’ADEME. Les sujets abordés établissent tous un lien for t entre recherche scientifique « académique » et recherche de solutions opérationnelles concrètes, démontrant ainsi qu’il est possible de mettre en oeuvre une recherche qui concilie sans les opposer les exigences de qualité scientifique avec des objectifs « finalisés » !
2. Caractérisation des ordures ménagères à Nouakchott: Partie I : Méthode d’échantillonnage
The first step in sound waste management practice is to characterize the waste stream quantitatively and qualitatively. This study was undertaken to test a waste characterization methodology designed to be appropriate for the specific socioeconomic context of developing countries. Specifically, this novel method allows quantification and characterization of household waste generation without data loss due to failure to account for local waste reuse practices during collection or transportation. Nouakchott, with a population that is heterogeneously distributed with respect to income level, was used as the test site. The study addressed household solid waste production at three different income levels (low, medium and high) during two distinct seasons (dry and humid). Statistical analyses ere developed and applied to pilot waste generation data to determine the sample size needed to achieve high precision (small sampling error) at the 95% confidence level. Samples of 28, 29 and 28 households were chosen respectively in low, medium and high income level sectors.
3. Caractérisation des ordures ménagères à Nouakchott : Partie II : Résultats en saison sèche et en saison humide
Characterization of the Nouakchott household solid waste stream destined for landfilling revealed a waste density of 0.41 kg/m3 and a moisture content of 9%, which is low compared to other countries. Generation rates averaged 0.21 kg per capita day?1 (0.19; 0.23 and 0.22 kg per capita day?1 respectively at the low, medium and the high income level). These rates do not show a relationship between income level and quantity of waste generated, and this is likely due to the contribution of fines in the waste stream. When the fines are neglected, there is a clear increase in per capita waste generation rate with income level (0.12; 0.15 et 0.18 kg per capita day?1 respectively for the low, the medium and the high income residents).The low generation rates of household waste in general in Nouakchott are due to the fact that the organic fraction of the waste stream is traditionally withheld for use as supplementary feed for domestic cattle. This practice constitutes source reduction, and when this waste stream is taken into account, the amount of household refuse produced in Nouakchott is about 0.35 kg per capita day?1, with generation rates of 0.30; 0.34 and 0, 40 kg per capita day?1 respectively at the low, medium and the high income levels. There were distinct seasonal variations, with a relatively significant increase in waste generation rates in the dry season compared to the wet one. The most important difference was obtained in the low income strata, where the dry season […]
4. Evaluation de l’efficacité de trois méthodes d’extraction d’ADN de la biomasse microbienne totale du compost
DNA extraction from compost make easy the detection of microorganisms non discernable by classic and usual methods. In fact, we have examined three different methods and try to perform them. So, we found an important level of cell lysis by the freezing thawing cycles, we found also the important elimination of impurities by CTAB-PVPP, it is shown by a clarification of the samples. The mix PEG-NaCl made a good purification of the DNA.
5. Collectivités et prestataires de services : enquête exploratoire pour la collecte des déchets ménagers
Private management of local waste has been scarcely studied although this question shows an original technico-institutionnal pattern in the field of local urban management. Under the rule of the “Code des marchés publics”, arrangements are made on a pluriannual basis. Such a legal framework is supposed to imply competitive procedure and thus to strengthen the decision making process of local authorities. Yet, the actual control of public authorities over this relationship is put under question. This article – based on a number of empirical studies — deals with this matter. It reveals what is at stake by studying closely the actual process of a contract between a local authority and a firm.
6. Politiques intégrées des déchets et des produits ; recherche de points d'appui et d'instruments adéquats
The policy of waste comes more and more within the scope of an integrated product policy, that is to say not only end-of-pipe but preventive measures. The main axes are cleaner technologies, cleaner products, eco-consumption and recycling.A strategic approach is required to ensure the effectiveness of the policy, in the frame of a product chain pressure point analysis or a leverage point analysis, in order to maximize the induced effects. Moreover appropriate instruments have to be chosen (and combined) to ensure effectiveness and economic efficiency. Cost/effectiveness ratios may be calculated.Environmental protection needs command-and-control, but the part of economic instruments is increasing and suasive instruments may play an interesting role. The paper provides concrete examples on this topic. The “extended producer’s responsibility” (EPR) appears as a new major principle, with applications to an increasing number of products. There is a relation with deposit-refund systems, which are effective but not always efficient, depending on logistic aspects. Concerning EPR, the paper deals with the following main questions: channeling of the responsibility; transition from an individual to a collective responsibility with the building-up of eco-organizations; choice between global or “segmented” recycling objectives; unicity or multiplicity of eco-organizations; producer’s total or partial responsibility; consumer’s information; judgment in respects to […]
7. Pollution des sols moldaves par des pesticides organochlorés
High concentrations of HCH (hexachlorocyclohexane) and DDT (dichlorodiphenyltrichloroethane) were found in moldavian soils. Elevated levels of organochlored pesticides correspond to soils situated near the storehouses. Soil presents great levels of HCH-isomers and DDT-isomers with a prevalence of α-HCH, β-HCH, pp’DDT and pp’DDE. Concentrations of total-DDTs determined in soils from the storehouses ranged from 0.03 to 118 mg/kg and the values of total-HCHs ranged from 0.07 to 1180 mg/kg. We have found the same molecules in agricultural soils situated near the warehouses but with lower concentrations of pesticides. Concentrations of total-DDTs browsed from 0.07 to 0.900 mg/kg and the total-HCHs was from 0.05 to 4.5 mg/kg. These results denote a possible recent input of HCHs and a decomposition of DDTs from “old sources” in soils of the samples areas.