| Environnement, ingénierie & développement |  |
N°68 - Novembre 2014
1. Recommandations sur l’utilisation des outils de prédiction du drainage minier acide
The sulphidic tailings subjected to the atmospheric water and oxygen action may generate acid mine drainage (AMD). AMD is due to the oxidation of sulphide minerals they contain in the absence of a neutralizing potential. The effluents related to AMD are acidic, metal loaded and are often harmful towards the surrounding environments. A reliable prediction of this phenomenon to preserve the environment is of great importance as it is able to impact the costs and the ways to restore mines sites. The most frequently tools used for AMD prediction are static tests and kinetic tests when the first provide uncertain prediction results. AMD perdition tests are available in several versions whose protocols are quite divergent. Also, there is no guide orientating users in their choice. Thus, the objective of this review paper is to give clear recommendations to help choosing among either static and kinetic tests for AMD prediction based on tailings intrinsic characteristics (for static tests) and on the objectives of the study (for kinetic assays).
2. Essais d’aptitude au traitement des sédiments de dragage marins en vue de leur valorisation en techniques routières
In this paper, results for an European project called SETARMS which aims to find innovative and sustainable solutions for marine dredged sediments in order to reuse them in road construction. After a first stage of a geotechnical characterization of sediments according to the GTR, the GTS recommendations were adopted to treat sediments with hydraulic binders. Hence, a formulation composed of 3% of quicklime and 6% of cement was applied for height different sediments. Specific ability tests were conducted in order to measure volumetric swelling and indirect tensile strength. Obtained results show that even if raw sediments belong to the same GTR class (A1 or A2), the treated samples respond differently to the adopted treatment formulation. Results of mechanical performance with the cure age show that most sediments don’t reach the needed criteria for reuse as sub-grade layer.
3. Valorisation de déchets de poisson alliés à des rejets brassicoles en vue d’obtenir un biofertilisant
Food industry in Morocco generates continuously many organic wastes that pose both economic and environmental problem. Yet their valuation can procreate new economical source.This study seeks to enhance industrial fish waste in combination with biomass yeast rejected by the brewing industry; to create a starting mixture of nutritionally balanced its contents in basic element: the triplet nitrogen / carbon / phosphorus.Several binary mixtures are then developed with the aim of seeking the optimal formula. The compositions were followed for two weeks at room temperature under a continuous stirring using benchtop stirrer , pH, conductivity and temperature were monitored daily. Other parameters, such as the measurement of the dry matter, nitrogen, phosphorus, trimethylamine and microbiological were controled in the beginning, middle and end of the study.The results show that product is mature after eight days, it is odorless, pH is stable, have good hygienic quality and it is rich in nitrogen and phosphorus. The tests on species of barley Hordeum vulgare and tomatoes Lycopersicon lycopersicum, show that it improves the growth properties of their cultures.
4. Gestion des déchets dans les villes en développement : transfert, adaptation de schéma et sources de financement
The urban solid waste management sector in Developing Countries encounters difficulties and great challenges. Scientific research data show that it is possible to control the waste management if the households or the first line actors are accountable or if the polluter pays. It appears from this study that the organization of the urban waste collection in Developing Countries may be inspired by what is practiced in Canadian cities, namely the City of Trois-Rivières, Quebec. Although the composition of their waste is not identical, the funding sources of waste could be mirrored. The structured subdivision and occupation of the territory and the availability of a municipal tax account to every citizen or household or home in Trois-Rivières facilitates the collection of the taxes and the fees to finance the waste management. The development, the implementation and the monitoring of regulations are also of great help to solve the management problems in this sector. On the basis of assets available to developing countries, a scenario to levy taxes for the urban salubrity or for the sustainable development could be based on some taxation vectors considered as priorities by the population, namely Mobile phone, electricity consumption, running water or oil products. So municipalities in developing countries can face their responsabilities in this area and get rid of the burden of some of external fundings.
5. Co-compostage de résidus solides de toilettes sèches mobiles en présence de déchets verts
Among techniques for human solid and liquid wastes management and treatment, Dry Toilets (DT) are often used as a possible solution for flush toilets issues. Highly developed in Scandinavian countries, the principle of DT is to collect separately urine and feces, mixed with a solid absorbent. DT technologies have an advantage to allow human wastes to be directly valorized, without dehydration after composting as a fertilizer for agriculture. However there are still few scientific researche to determine the optimum composting process conditions for these kinds of wastes, to comply with composts quality and safety.This study is especially interested to Mobile Dry Toilets (MDT) and considers the option MDT wastes co-composting with vegetable wastes. This experimental aim is to study MDT wastes biodegradability under aerobic conditions, by considering their mixing with or without vegetable wastes in different proportions. Performed on MDT residues collected on electronic festival music, the samples’ bio-physico and chemical characterization has highlighted the absence of pathogens after 6 months in storage tanks and showed the biodegradation ability of such residues in aerobic conditions mixed with vegetable wastes. Highlighting several pharmaceutical micropollutants (such as no-steroidal anti-inflammatory drugs, analgesics, antibiotics, hormones) and drugs (such as opiates, cocaine, amphetamines and cannabinoids compound families) has led to interest in their fate during […]