| Environnement, ingénierie & développement |  |
N°39 - 3ème Trimestre 2005
1. Editorial: Enjeux scientifiques, techniques et sociaux de la valorisation énergétique et matière des déchets (WasteEng2005)
La première Conférence internationale sur l’ingénierie pour le traitement des déchets : Valorisation des déchets et sousproduits — en anglais : 1st International Conference on Engineering for Waste Treatment : Beneficial Use of Waste and by-Products —, WasteEng 2005, ou « Comment transformer des déchets en énergie et en matériaux valorisables », s’est tenue à École des mines d’Albi-Carmaux du 17 au 19 mai 2005.Cet événement, organisé par l’Ecole des mines d’Albi-Carmaux (EMAC), en partenariat avec l’université Paul-Sabatier de Toulouse, le centre de PROMES-CNRS d’Odeillo, l’université de Tsinghua (Chine) et le New Jersey Institute of Technologies (NJIT, Etats-Unis), a rassemblé 275 représentants originaires de 40 pays. Cette conférence a été organisée avec le soutien de partenaires tels que l’Ademe, Onyx, Solvay, Sita, Inertec, l’Ineris, Lhoist, le CNRS-SPI, Setaram, la région Midi-Pyrénées et la ville d’Albi.La conférence a accueilli des contributions issues de l’industrie, de la recherche et des organismes institutionnels travaillant dans le domaine des procédés et technologies de traitement, de la valorisation et de la gestion des déchets.
2. Les cendres issues de l’incinération de farines animales : déchets ou produits valorisables ?
Since the widespread occurrence of bovine spongiform encephalopathy (BSE) in the 1990’s in Europe, Meat and bone meal (MBM) have been banned from animal feed and must be safely disposed of or transformed. Among the different processes studied, valorisation of MBM can be realised by a thermal treatment. Even if MBM combustion releases high energy, incineration produces huge amounts of ashes (20 to 35% of the initial weight depending of their origin), the valorisation of which could become a major concern. In France for example, with nearly 850 000 t of MBM produced each year, ashes production would exceed 150 000 t/year. Combustion ashes present high level of Calcium (nearly 31% weight) and phosphates (around 56% weight). X ray diffraction analysis of ashes show the presence of calcium phosphates mainly as a mixture of Ca10(PO4)6(OH)2 and b-Ca3(PO4)2. In our search for new valorisation ways, we show that ashes display high lead uptake capacity in water (about 275 mg/g of ashes) and could then be used for pollution remediation. This work also underlines that MBM ashes can present a phosphate source for industries (phosphoric acid production, agricultural soil enrichment…).
3. Valorisation d’un sous-produit de l’industrie sucrière : mise en œuvre dans un procédé de traitement d’eaux usées industrielles
Sugar beet pulp generated by sugar refining factories is a very cheap and available by-product. The aim of the present work is to develop a new dynamic process involving this low cost biosorbent in order to remove metal ions from aqueous solutions. As a preliminary step, a complete characterization of the polysaccharide has shown that sugar beet pulp contained about 20% galacturonic acid and 0.466 mmol.g-1 as carboxylic groups. The total cation exchange capacity (0.575 mmol.g-1) suggests good metal binding capacities. Then, batch adsorption studies were performed for several metal ions, namely Pb2+, Cu2+, Zn2+, Cd2+ and Ni2+ cations. For 8 10-4 M initial metal concentration, the initial sorption rates ranged from 0.063 mmol.g-1.min-1 for Pb2+ to 0.275 mmol.g-1.min-1 for Ni2+ ions. The equilibrium data fitted well with the Langmuir model and the maximum adsorption capacities ranged from 0.202 to 0.356 mmol.g-1 with the following affinity order: Pb2+ > Cu2+ > Zn2+ > Cd2+ > Ni2+. Ion exchange with Ca2+ ions neutralizing the carboxyl groups of the polysaccharide was found to be the predominant mechanism, added with complexation for Pb2+, Cu2+ and Zn2+ metal ions. The dynamic studies of Pb2+ and Cd2+ fixation onto the natural polysaccharide involve an adsorption reactor coupled with a microfiltration membrane in order to confine the particles. Due to their lower affinity for the biosorbent, Cd2+ ions were found to break through the process faster than Pb2+ cations. A […]
4. Systèmes d’échanges de droits : applications possibles au recyclage des déchets d’emballages en Europe
At first the concept of trading is reminded: principle, fields of application, interest – notably economic efficiency (that is to say cost minimization to reach an objective) – and limits, which deal with equity, administration, monitoring and transaction costs. The content of the European Union (EU) directive of the 20th of December 1994 on packaging and packaging wastes is reminded, in particular its quantitative objectives for recovery and recycling; moreover in 2004 a new directive has set more ambitious objectives.Towards these objectives, tradings may be applied at different levels and between various categories of packagings, materials, “agents” and products chains:* trading between the EU states members, with free negotiation or with a system which is managed by a EU authority;* trading within a country between households packaging and commercial or industrial packaging, with the same or different objectives for the two categories;* trading between the packaging materials, with the same or different objectives for the materials;* moreover the packaging chain concerns different categories of “agents”: producers of materials, manufacturers of packaging, packers or fillers, distributors, retailers and consumers; in some countries the responsibility is put on a category of agents, whilst in other countries it is a “shared” responsibility; and the chains concern categories of materials or products; the – complex – case of trading in the United Kingdom […]
5. Intéractions biogaz / mâchefers d’incinération d’ordures ménagères - Rétention d’H2S
The most utilised methods for municipal waste disposal in France are landfilling and incineration. Storage of organic waste materials to landfill in anaerobic conditions produces landfill gas, which contains enough methane for combustion and energy recovery; however, landfill gas also contains trace compounds that can be corrosive, aggressive and hazardous to the environment. Among these compounds, we were particularly interested in the main sulfur compound, H2S, which in addition, causes olfactory nuisances. Incineration produces mainly one solid waste: Municipal Solid Waste Incinerator (MSWI) bottom ash, which needs to be stored or reused after treatment.This study, supported by the Novergie company, focuses on a new way of reusing MSWI bottom ash in the treatment and purification of landfill gas. The overall study concerned the purification capacities of bottom ash either alone or as a part of a mixture (with coke) towards H2S and other potentially harmful landfill gas compounds. Only results concerning H2S are discussed in this paper. A pilot experimentation unit was developed and operated at the Biovale company engineered landfill (Loire). The purification potential of bottom ash from North-Lyon incineration plant was experimented on real landfill gas. The additional study of interactions between bottom ash and the two main compounds of landfill gas (methane and carbon dioxide) is particularly interesting within the context of a full scale implementation in an engineered […]
6. Approches du bilan hydrique de deux centres de stockage des déchets ménagers dans les pays en développement : cas de Go Cat (Vietnam) et Essaouira (Maroc)
Waste management in developing countries is a growing concern because of its impact on Man and on the environment. The traditional method, known as “landfilling”, is still the most widespread for solid waste disposal, because of its relatively low cost. In the developing countries, the insufficiency of financial and technical means too often causes the municipalities and the population to dump waste into uncontrolled sites. This study has been carried out within the frame program of the French Agency for Environment and Energy Management (ADEME), dealing with the landfilling of municipal waste in developing countries. The major objective is the definition of a methodology for designing and operating municipal waste landfilling facilities, suitable for developing countries. This paper presents the first results obtained on three sites, i.e. the lanfilling facility of Essaouira (Kingdom of Morocco), under mediterranean climate, the facility of Nkolfoulou, located near the city of Yaoundé (Republic of Cameroon), under equatorial climate, and the facility of Go Cat, located by Hô Chi Minh-City, in Vietnam, under wet tropical climate.