| Environnement, ingénierie & développement |  |
N°69 - Juin 2015
1. Étude expérimentale et modélisation de l’inhibition de la dégradation du propionate par les acides gras volatils en digestion anaérobie par voie sèche
Batch experimental assays were performed in or-der to assess the kinetics of propionate and acetate uptake in dry (high-solids) anaerobic digesters. The profile of propionate uptake was lower at high pro-pionate and acetate amounts. Haldane’s inhibition model for substrate inhibition and a non-competitive product inhibition by acetate were found to rule the observed phenomena. The inhibition constant for subs-trate inhibition was 2800 mgCOD of propionate per kg of digesting medium, while the inhibition constant for product inhibition was 4800 mgCOD of acetate per kg. These parameters were implemented in a kinetic model derived from ADM1 and adapted to anaerobic dry digestion processes. The model was able to fit sa-tisfactorily the experimental results.
2. Éditorial n°69 Déchets Sciences et Techniques
Chères lectrices, chers lecteurs, Depuis son précédent numéro, la revue DST a connu de profondes évolutions qui ont entrainé plusieurs semaines de retard dans la parution du numéro dont vous entamez la lecture. Au nom de toute l'équipe éditoriale, je présente nos excuses pour ce retard à nos lecteurs et à nos contributeurs, en espérant qu'ils comprendront que de telles évolutions devaient se faire sans précipitations pour être utiles et durables. Précédemment éditée et diffusée par la société COGITERRA comme supplément scientifique de la revue Environnement & Technique, c'est aujourd'hui l'INSA de Lyon qui est l'éditeur scientifique de DST.
3. Analyse comparative des résultats de caractérisation d’ordures ménagères : cas des communes de Bembéréké(Bénin), Kinama (Burundi), Gombe et Kimbanseke (RDC)
In subtropical Africa, in the context of decentralization, waste management is municipal jurisdiction. The lack of local and updated data increases the risks of failure of waste management projects. Indeed, the characteristics of waste are valid in a given place and for a given moment; thus, every municipality which wishes to manage its waste should have at first their typology. We tried to specify it by recent results of characterization of household solid waste. These results were obtained by an same method which takes into account seasons and local sociodemographic data. The statistical tools such as analysis of variance (ANOVA), comparison of averages test and Chi-squared test (X²) were used for the comparative analysis of the seasonal productions, the annual productions and the relative compositions of household solid waste, respectively. In 3 of 4 cases the obtained production of household solid waste is upper to the average production of 1996 for low-income countries (of whom they are a member); besides, the obtained average composition follow the global typological trend of household solid waste in developing contries. In Kimbanseke, the production of household solid waste differs significantly among seasons. Between four studied municipalities, the production of household solid waste not significantly varied; but, in their composition, very significant differences appeared. However, for these four municipalities, the characteristics of household solid waste not […]
4. Analyse des systèmes de gestion des déchets par l’étude du mécanisme de répartition des déchets
The strengthening of the competitive use of waste leads us to concentrate our attention on the waste supply processes between recovery and disposal sectors from the standpoint of the waste circulation in a waste management system. This article aims to develop a theoretical framework around the concept of apportionment mechanism of waste that designates the waste distribution process between disposal and recovery sectors which are located inside or outside of a waste management system. This framework is based on the design of a conceptual framework for describing the apportionment mechanism of waste in which a theoretical model of explanation and prediction is inserted. The conceptual framework and the theoretical model are both based on the multidisciplinary concept of « black box ». The defining of the theoretical framework will lead then to design an analysis framework devoted to the empirical study of the apportionment mechanism of waste which will provide a new research perspective for the analysis of waste management systems.
5. Amélioration de la biodégradation du biphényle par Rhodococcus erythropolis t902.1 en présence de Fe2O3 et de nanoparticules de fer encapsulées dans un xérogel de silice
In this work, the effect of iron oxide particles Fe2O3 and iron nanoparticles encapsulated in a porous silica matrix (xerogel Fe/SiO2) was investigated on biphenyl biodegradation by the strain Rhodococcus erythropolis T902.1. After 18 days of incubation biodegradation yields of 75% and 85% were achieved respectively in presence of non-autoclaved or autoclaved xerogel Fe/SiO2at 10-5 M iron. These results are 42 and 60% higher than in standard conditions without nanoparticles. They suggest that the autoclave procedure lead to the release of some iron less anchored in the silica matrix. This study highlights that siderophore production byRhodococcus erythropolis T902.1 would be related to the presence of iron nanoparticles in the culture. It suggests that the production of these strong chelating compounds decreases with increase of iron release from xerogel Fe/SiO2. Moreover, most of the surfactants synthesized by Rhodococcus erythropolis T902.1 which are glycolipids containing trehalose (hexose),would be linked to cell surface and not excreted in the culture medium; the biomass hexose content also increased by 85% in presence of iron nanoparticles.
6. Valorisation des DEEE par l’extraction des terres rares, métaux précieux et matières plastiques
The approach proposed in this work present clean processes for the treatment and recycling of waste electrical and electronic equipment, under the protection of the environment paradigm, especially for computers and mobile phones which are classified in category 3: “it and telecommunication equipment” according to the European directive 2002/96/EC through the extraction of precious metals, rare earths and possibly plastic granulates. The proposed solution is adapted to the specificities of Morocco by implementing a scheme of appropriate ecological treatment consists of: 1) Processing of non-ferrous pyrometallurgical aggregates isolated, 2) Recovery of gold from gold coins by hydrometallurgical 3) Identification of rare earth from monitors 4) Manufacture of hydraulic plaster from residual waste (mixture of plastics, resins and ceramics). This work also focuses the possibility of rationalizing the consumption of natural resources by minimizing the need for raw material (e.g. Cu, Al, Au, Pd, plastics,) by the transformation of electrical and electronic waste (WEEE) in resources.