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École Polytechnique Montréal (1995)

Perspective des eaux usées au Sahel : gestion et traitement

Garba, Laouali

Titre : Perspective des eaux usées au Sahel : gestion et traitement

Auteur : Garba, Laouali

Université de soutenance : École Polytechnique Montréal

Grade : Doctor (Ph.D.) 1995.

Poor public sanitation is one of the principal problems of towns in developing countries. The situation is deteriorating steadily with rapidly advancing urbanization and the lack of adequate infrastructures for the collection and treatment of wastewater. As a result, water-borne diseases are a permanent threat to public health in these areas. With their very limited resources and the number of higher-priority problems to be resolved, the authorities there have no choice but to treat this as an issue of secondary importance. It is difficult in this context, however, to justify the adoption of an approach that would solely involve the treatment of wastewater for the protection of receiving bodies of water and public health. In a semiarid region like the Sahel, the value of wastewater both as water resource and as fertilizer must be exploited. The approach which we recommend is to collect the wastewater for treatment and use it for various purposes, particularly agriculture. This approach would not only reduce the health risk of untreated water, but would give wastewater management a socioeconomic value which would justify investment in the domain. To demonstrate the viability of such an approach, a preliminary study on the reuse of wastewater for overhead irrigation in nurseries has been carried out in Niger. The experiment was designed to compare the advantages of overhead irrigation using wastewater and irrigation using traditional water sources : river water and well water. Species generally used in the fight against the principal environmental threat in Sahelian countries, desertification, were selected for the experiment in two Nigerien locations : Acacia nilotica (L.) Wild., Propopis juliflora, and Azadiracha indica Lam. at Maradi ; and Azadiracha indica Lam., Cassia siamea, and Delonix regia (Boj.) Raf. at Niamey. The untreated raw water posed no particular risk, but rather demonstrated its usefulness in terms of an improvement in growth rates. In the case of tree height, improvements in cumulative growth in the order of 40 to 400% were recorded at Niamey, and in the order of 15 to 100% at Maradi, in three- and two-month growing periods respectively. Thus, the adoption of wastewater reuse in nurseries will not only reduce the growth period of plants and improve their productivity, but, above all, will result in the development of a significant water resource industry as well. Viewed from this perspective, the solution to the wastewater problem can also provide a means to improve the effectiveness of the various reforeatation programs established in the fight against the encroachment of the desert.

Mots Clés : Wastewater, Sanitation, Applied sciences, Environmental engineering, Civil engineering, French text irrigation, Agricultural engineering

Présentation (ProQuest)

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