| Environnement, ingénierie & développement |  |
N°26 - 2ème Trimestre 2002
1. Éditorial n°26 Déchets Sciences et Techniques: MIOM 2001. Les leçons d’un colloque
Il y a exactement 6 mois se déroulait en 2001 à Orléans, un colloque sur les mâchefers d’incinération d’ordures ménagères (MIOM) organisé conjointement par l’Ademe et le BRGM : « MIOM 2001 : Quel avenir pour les MIOM ? ».Lancée au cours d’une discussion avec le professeur Alain Navarro de l’INSA de Lyon en 1999, l’idée du colloque est née du constat qu’il n’existait pas encore d’état de l’art sur les MIOM et que cette manifestation apporterait une première réponse. L’organisation de ce colloque en 2001 était d’autant plus opportune qu’elle se situait à une période clé de l’évolution de la réglementation : le passage de la circulaire mâchefer (circulaire ministérielle de mai 1994, DPPR/SEI/BPSIED n° 94-IV-1), dont l’utilisation est aujourd’hui étendue à la majorité des résidus de procédés thermiques (RPT), à une circulaire (en cours de rédaction) qui aura pour objectif de définir puis réglementer un usage et une déontologie pour tous les RPT.Le succès indéniable de cette manifestation, 210 inscrits, de toutes les communautés (industriels de l’incinération et des travaux publics, élus, personnel des services techniques de l’Etat et des collectivités territoriales, universitaires, membres d’instituts de recherches, d’organisations non gouvernementales…), montre le besoin de communication et d’échanges autour de cette thématique sensible. Mais, la dynamique entraînée par une telle […]
2. Présence des matériaux non ferreux dans les mâchefers d’incinération d’ordures ménagères: Gisement, caractérisation et exploitation
The extraction of aluminium nodules from incinerator bottom ash is a profitable operation and provides “demetallized” bottom ash fit for various uses, such as road ballast. The aluminium particles, generally from 5 to 60 microns in size, are ejected by an eddy current machine (ECM), of which 44 units had been installed in France by the end of 2001, producing altogether 12,400 tonnes of nodules. The French “aluminium-scrap mine” has a potential of 30,000 t/year; with an extraction yield of 70%, this should lead to a production of over 20,000 t/year in the medium term. The non-ferrous content of bottom ashes ranges from 0.5 to 1.5% with a 1% average. For a proper optimization of aluminium-nodules extraction on a specific platform, experts from France Aluminium Recyclage provide technical assistance through: (1) analysis of the grain size distribution of the nodules; (2) estimates of the aluminium content of each fraction; (3) guidelines for the configuration of the ECM to be installed, depending on the objective (maximum aluminium extraction or production of a specific road-ballast quality). In all cases, the technical solution will be financially self-supporting for the range of contents mentioned, thanks to the value of aluminium scrap.
3. Recyclage de mâchefers par fusion réductrice
Recycling of bottom ashes by melting under reducing conditions by the electroslag process allows us, in a zero waste policy, with an energy expense of 300 kWh/t on hot ashes and for a total cost of 68 €/t to recuperate around 800 kg of a clean slag, 80 kg of iron and 20 to 30 kg of fly ash. The liquid slag can easily be transformed in raw materials for the building industry : reinforcement filaments or porous materials for light weight concrete. The iron can be recycled in foundries. The different heavy metal compounds of the fly ashes can be separated by conventional processes and recycled as pure metallic salts in the non ferrous industry.
4. Nouvelle technologie de fours d’incinération permettant d’assurer une qualité de mâchefers et de gaz optimale: La grille refroidie à l’eau Stiefel – Vinci Environnement
Facing simultaneously changes in waste streams features, ecological constraints and economic targets, waste to energy techniques has to meet new challenges. New technologies studied some years ago allow to have continuous and steady improvements in waste-to-energy facilities efficiency. Thus, water-cooled grate solutions can now be installed for municipal and household waste. Even for common values of NCV, municipal household waste can benefit of this new technology : longer lifetime of grates, combustion control and gaseous emissions control, quality of bottom ash. On this specific aspect, results show excellent quality of bottom ash after combustion with a water-cooled grate incinerator.
5. Simulation du comportement des métaux lourds dans les procédés d’incinération d’ordures ménagères
6. Placement optimal des capteurs et actionneurs d'un bioprocédé
This paper deals with the optimization of a complex anaerobic process operated to produce easily biodegradable matter to be used in denitrification processes as external carbon source. The optimal configuration, number and accuracy of actuators and sensors is derived using a new theory allowing the tradeoff between the performance to be obtained and the quality (and thus the price) of process components. The principle of the approach as well as the optimization results are presented and discussed.
7. Etude de la biodénitrification sur support ligno-cellulosique en présence de 4-éthylphénol
In some Moroccan areas, ground waters are contaminated with nitrates. The concentrations can reach 100 to 400 mg/L. Such ground waters are the only source for rural people daily demand. Therefore, itis needful to ensure a rustic denitrification treatment.In the lab, a biodenitrification process has beenstudied using reed cellulose as carbon source andreducing agent. Moreover, the denitrified water(NO3- < 50 mg/L, NO2- < 0,1 mg/L) contained organicmatter. As the last step of treatment chain waschlorination, THMs were formed in levels higher asallowable.So, reed and the effluent were extracted with organicsolvents and a few organic compounds, especiallyphenols, were identified by gas chromatographycoupled to the spectrometry of mass (GC/MS).Therefore, the aim of this work was the study of the 4-ethylphenol effect on the biodenitrification. Thismolecule was present in both, reed and denitrifiedwater.Series of experiments has been conducted as described:Experiment 1: reference assay with reed cellulose,Experiment 2: tests with reed chips and 4-ethylphenol,Experiment 3: assays with 4-ethylphenol and without reed (table 3),Some 250 mL vessels were filled with solutioncontaining nutrients (nitrate and phosphate), the pHwas adjusted at 7,5 with NaHCO3 and NaOH. Then the solution was deaerated by nitrogen bubbling for 10 minutes and isolated from atmosphere through a water bath (figure 1). The yield of denitrification was calculated after analysis of nitrate and nitrite ions […]
8. Étude de la faisabilité du traitement des boues de rectification en vue de leur valorisation
The aim of this paper is to study three separation processes to separate metallic particles from grinding sludge. Indeed, considering their high concentration in steel, the grinding sludge can be valorised in several industries such as cement works and pyrometallurgy factories. The treatments investigated are aqueous surfactant cleaning, organic solvent washing and mechanical compression. This study illustrates low efficiency of surfactants (around 20%) to remove the organic content (cutting oil and lubricants) of the sludge. In contrast, better efficiencies (around 90%) are obtained with non-polar organic solvent washing and with mechanical compression, allowing the valorisation of the sludge in pyrometallurgy factories. However, the yields obtained are insufficient for cement factory valorisation. Thus, combination of these treatments is recommended.