| Environnement, ingénierie & développement |  |
N°71 - octobre 2016
1. Vers une économie circulaire... de proximité ? Une spatialité à géométrie variable
The proximity principle is one of the main obligations in the European and French regulations regarding waste management. However, this principle isn’t really implemented as it isn’t well defined in the law. Proximity is also linked to the new consensual concept of circular economy, which highlights the local scale (even if the local is not mentioned in its definition). The objective of this text is to understand the implementation of the proximity principle in the concept of circular economy according to the waste recycling chains. The methodology is based on analyzing the urban metabolism for few cities and interviewing stakeholders of waste management.The implementation of proximity is quite complex and affected by the “geometry variable” according to the types of waste. Some of them are managed at local scale such as the putrescible and fermentable waste, the bulky refuse, and final waste. Others are easy to transport (e.g. waste with high value added or hazardous waste). We aim at identifying the criteria which determine these geographical issues. The complexity of Extended Producer Responsibility implementation is one of the key to study the spatial analysis of circular economy. All of these case studies give the opportunity to understand the geographical scale of the circular economy’s implementation.
2. Éditorial n°71 Déchets Sciences et Techniques
Chères lectrices, chers lecteurs,Près d’une année s’est écoulée depuis la parution du numéro 70 de DST précédant celui-ci. Ce délai est largement supérieur à celui auquel nous avions habitué nos lecteurs au cours des dernières années. Il n’est pas conforme non plus à l’objectif affiché par l’équipe éditoriale de rechercher une fréquence de publication de 3 numéros par an.Plusieurs raisons expliquent ce retard. En premier lieu, nous avons travaillé, en parallèle à la préparation de ce numéro 71, à l’édition d’un numéro spécial de la revue qui publiera une sélection d’articles étendus issus du colloque scientifique international "Eau, Déchet & Développement Durable" (E3D 2016) organisé par l’Université de Lomé, Togo, du 7 au 11 mars 2016. Ce numéro spécial devrait regrouper 6 articles et paraitra dans un mois seulement. Nous verrons donc in fine la publication de deux numéros en 2016, mais à un intervalle très rapproché l’un de l’autre.D’autre part, malgré nos efforts, la procédure d’examen des manuscrits par deux lecteurs experts est relativement longue, car elle exige souvent plusieurs allers-retours entre les auteurs et les lecteurs pour aboutir, lorsque le manuscrit est accepté, à la version définitive qui pourra être publiée. Cette procédure est cependant indispensable pour garantir l’originalité des articles et le niveau de qualité permettant à nos lecteurs de trouver intérêt […]
3. Comportement des déchets en décharge sous climat tropical humide : cas de Nkolfoulou à Yaoundé
The parameters analysed concern: density, water content, temperature and permeability.The density of buried waste is measured into two stages: the excavation of a volume of waste obtained by the cubage of excavation, then removed waste is weighed. The excavation is carried out in several cells of various ages and various depths. The water content of hidden waste is measured directly by drying samples at a temperature of 90 °C until constant mass. The permeability of the cells is measured by the method of double ring, then the coefficient of permeability is calculated. Two methods are used to measure the permeability of hidden waste: method of double rings and method of excavations.The density of hidden waste varies with age and depth of the layers. Younger waste has an average density of 0.9. This density increases with age of waste to an average value of 1.3 after one year. The season has little influence on the density of hidden waste.The results of the water content of the waste buried in the dry season show an increase in values with depth : it goes from 36.3 % (0-1 m) to 77.0 % (1,2-2,4 m) . Another test conducted in the same cell confirms the increase of the water content with depth but with lower values than those of the previous test: 40 % (0-1 m) and 43 % (from 2.2 to 3,6 m). During the rainy season, the change in water content with depth is sharper (51 % between 0 and 1 m, against 76 % between 2 and 3 m) for waste one year of age. We can conclude that the influence […]
4. Dosage rapide sur site des sulfates dans les granulats recyclés issus du BTP
In 2012, the sector of building and public works generated nearly 250 million tons of mineral waste. Reuse of these deconstruction materials in roads is subject to compliance with geotechnical and environmental requirements. The latter impose to carry out regular controls of the quality of the material produced, in particular with respect to their content of water soluble sulphate, which may promote detrimental expansions in concrete structures. To simplify these control operations and improve responsiveness on production platforms, the aim of this study was to develop a field method to measure soluble sulphate content in recycled aggregates. The method was performed in laboratory and then on a recycling platform. It is based on a sampling adapted to field conditions and provides an estimate of the sulphate concentration by a visual method using the Visocolor® kit. This work also helped to provide a warning value for materials having a sulphate content higher than the 0.7 % compliance level. But more field data are needed to make this warning value more reliable.
5. Etude de l'impact sanitaire et environnemental des déchets hospitaliers dans 4 éblissements hospitaliers de Kinshasa en RDC
In DRC, hospital waste correspond to a mixture of the waste similar to household waste (DAOM) and waste of Infectious clinical activities (HCW). As part related to hospital hygiene, our study focuses on the impact of clinical waste in the workplace and the environment.For the workstation, on 20 selected people, more than 70% suffered from chest tightness, organic dust syndrome, dryness of the throat and nose, fungi and actinomycetes. About 40% have suffered from gastrointestinal disorders in the handling of hospital waste (from collection to treatment / disposal).From an environmental perspective, the physicochemical characterization of the outgoing storm water litter deposits from four selected hospitals (CUK, HGRK, HGRN, and HGK) show high levels for most of the parameters studied. For the first campaign carried out in 2006, the ratio of BOD5 / COD is 0.08 leachate. Based on available data, the pollution load is composed of chloride (5529 mg / l), COD (890 mg / l) and Cd (20 1 g / l). The electrical conductivity is 25,80 µS cm-1, the pH is basic (9 07) and the average is T ° (27 03° C). For the 2011 campaign, the ratio of BOD5/ COD has a higher value of 0.46; the chloride concentration was 177.17 mg / l and the MEST reach the value of 231.40 mg / l. The value of AOX concentration is 0.89 mg / l.These results indicate the existence of toxic substances in the leachate that may impact on the environment. This finding is reinforced by the analyzes in the river waters that […]
6. Le titane dans les sédiments de l'assainissement pluvial urbain : sources, concentrations, mobilités
Titanium is largely used in the urban environment. The purpose of this study is to characterize the titanium geochemical signature in urban stormwater sediments. Firstly, we compared the titanium, iron, silica, copper, zinc and lead content in 800 river sediments collected in Europe with the content of 19 urban sediments collected in stormwater infiltration basins in Lyon. Even if the total titanium content is not higher in urban sediment (mean of 2,7 g/kg) than in river sediments (1,5 à 4,0 g/kg), urban sediments concentrate titanium in comparison to other main minerals like silica and is correlated to heavy metals. Thus, the urban environment produce eroded particles that have a specific geochemical signature. Secondly, the study of the potentiel soluble or colloïdal mobility of titanium in urban sediment through batch experiments shows that titanium has a very low mobility in soluble or colloïdal form (less than 0,005% of the total titanium content). The organic matter present in urban sediment is supposed to play a major role on the limitation of the mobility of colloïdal titanium.