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14th IWA Specialized Conference on Small Water and Wastewater Systems, Nantes, FRA, 22-/10/2017 - 26/10/2017; International audience; Wastewater management in the French Overseas Territories (FOT) are lagging behind France mainland and both French and European regulations. Municipalities are characterized by resources weakness in terms of self-financing capacities as well as skilled human resources for maintenance. Treatment technologies selection and choices made for systems designs are suffering from missing knowledges on their operation in tropical conditions. Implementing a wastewater treatment plant (WWTP) in tropical conditions requires feedbacks on technologies behaviour under the tropics and knowledge of raw wastewater in order to adjust system design. Consequently a study has been conducted to compare treatments technologies performances, in real operating conditions, in order to optimize public investment by implementing suited systems to local constraints. The study has been focused on the five FOT (Martinique, Guadeloupe, Mayotte and La Réunion islands and French Guyana) and treatment plant capacities between 20 and 2 000 people equivalent (p.e.). Comparison of raw wastewater from small communities in the FOT and in French rural areas shows no major differences in terms of average concentrations. Upper bounds of the ranges of variations suggest that sometimes, highly concentrates influents reach the WWTP. The p.e. pollutants production has been evaluated at 60/130/65/17/2.5 g/d for small communities in FOT for BOD5/COD/TSS/KN/TP respectively. Performances comparison on the 4 treatments technologies the more implemented (activated sludges, natural ponds, rotating biological contactor, and vertical flow constructed wetland) gives important feedbacks: • Activated sludge is the main technology implemented in the FOT (70%), but the least reliable. Sludge leakages are noticeable on 10% of the campaigns. Lack of nitrification observed suggests maintenances troubles. • At low loads, algae prevent ponds from achieving French minimal regulation objectives for the removal rates. • Settling troubles have been identified on RBC. • With all the regulatory objectives fulfill with a 90-95% frequency, VFCW is the most reliable technology. It requires space and can't be implemented everywhere, even if tropical design has reduces the footprint (0.8 m²/p.e.). VFCW can reach high level performances (125 mgCOD/L), but shows also its limits (70% of NTK removal achieved by 75% of the sampling campaigns). Designs adjustments like unsaturated/saturated system or higher filtration layer enable adaptation to different objectives.

The Amazon is the largest tropical forest area on Earth, and has been undergoing rapid deforestation for the last four decades. In the Brazilian Amazon, large-scale pasture for cattle ranching and soybean production are the main land uses, leading to a yearly deforestation rate of 0.5%. These conversions are mostly located in frontier areas distributed along the so-called "arc of deforestation". Within this large zone, various land use change processes are interacting through several modes of land valuation and organisation. From several case studies in the State of Para (Brazil), the current project aims at analysing how landscape dynamics are related to infrastructure development, ecological conditions, zoning policies and to the evolution and the organisation of the production, consumption and marketing chains of livestock products. This paper presents the results for one test site, the region of Sao Felix do Xingu, South of Para. This region is the focus of land speculation, cattle expansion, and deforestation. Road construction, investments in electrical energy, financial credit for cattle, and the land reform policies have all fuelled this process. All these factors make this region one of the most dynamic agricultural frontiers in the Brazilian Amazon. The main objective of the paper is to improve our understanding of deforestation processes by crossing spatial analyses and livestock economics studies, and to characterise the role and impact of various natural and anthropic factors in the location and development of the main types of farmers, and their policy implications. © 2002 Elsevier Science B.V. All rights reserved.

National audience

National audience

International audience; Les systèmes de production bananiers des Antilles Françaises ne sont pas durables. En effet la monoculture qui les caractérise se traduit par une infestation de nématodes qui a pour conséquence la diminution des rendements, l'augmentation des coûts de production et un contrôle chimique excessif mettant potentiellement en péril la santé humaine et la biodiversité. L'introduction de jachères valorisées en pâturages ou de cultures fourragères apparaît donc comme un moyen de contrôle plus efficace du parasitisme. De plus, les feuilles, pseudo-troncs et écarts de triage des fruits, c'est-à-dire plus de la moitié de la production des plantations bananières, sont actuellement négligés alors qu'ils constituent une source alimentaire pour les animaux. La faisabilité d'un système de production mixte banane/élevage, basé sur la valorisation de la plante entière et l'introduction de jachères, a été étudiée grâce à un modèle de programmation linéaire (visual basic sur excel). La fonction-objectif était la maximisation de la consommation des aliments produits sur l'exploitation par des bovins, ovins, caprins et porcins. Selon l'option, la jachère était constituée d'une prairie naturelle ou d'une plantation de canne à sucre fourragère.Les porcs ne permettent pas de valoriser au mieux la bananeraie car ils ne consomment qu'une part réduite des sous-produits et doivent être complémentés. Les ruminants optimisent la consommation des sous-produits, les petits ruminants étant plus efficaces en cela que les grands ruminants. Le chargement animal permis est très élevé, particulièrement avec la canne à sucre. Des investigations supplémentaires sont nécessaires pour optimiser la productivité de l'exploitation mixte, d'une part par l'augmentation des quantités ingérées d'aliments de plus faible teneur en matière sèche, d'autre part par l'augmentation de la disponibilité de protéines pour les ruminants.

Diplôme : Thèse

Diplôme : Mémoire

International audience

International audience

International audience; Experiments were carried out to determine the effects of supplementation upon milk production and growing performances of Martinik hair sheep. Ewes weighing 49 kg LW were used in a 2-season experimental study. In the first trial, 3 energy supplement levels were offered to ewes suckling single lambs. The adjusted level (A, 8 ewes) was supplied to ensure that the litter had a daily weight gain (DWG) of 250 g. High (H, 8 ewes) and low (L, 8 ewes) levels were 150% and 75% of level A, respectively. In the second trial, comparative use of the H level was studied with 3 animal requirement levels: ewes suckling single lambs (SI, same ewes as H ewes), twins (TW, 8 ewes) and triplets (TR, 6 ewes), respectively. The experimental design was replicated in a second lambing season. The basal diet was chopped Digitaria decumbens hay (0.6 UFL, 4.6% CP) offered ad libitum. Supplements were composed of maize (65% ), soya bean (3% ), fish meal (8% ) and dehydrated alfalfa (24% ). The milk production (MP) of ewes on the L diet was lower ($P < 0.05$) than that of ewes on the A and H diets: 1142, 1415 and 1518 g$\cdot$d$^{-1}$, respectively. H-fed ewes fattened during the lactating period while A and L ewes respectively maintained and lowered their body condition score (BCS). Differences recorded for lamb DWG were low, but this trait reached a maximum of 248 g$\cdot$d$^{-1}$. MP varied significantly ($P < 0.05$) according to the litter size. Individual DWG was different for single, twin and triplet lambs ($P < 0.001$): 261, 188 and 143 g$\cdot$d$^{-1}$, respectively. In intensive breeding conditions, recommended daily energy allowances taking into account a good BCS of ewes for successive reproduction are 1.47 UFL for single-suckling ewes and 2.17 UFL for twin-suckling ewes, in order to obtain a DWG of the litter of 250 and 400 g$\cdot$d$^{-1}$, respectively.; Alimentation des brebis allaitantes Martinik élevées dans des conditions intensives : effets de différents niveaux de concentrés ou de la taille de portée. L'effet de la complémentation sur les performances des ovins allaitants a été étudié chez les brebis à poils Martinik pesant 49 kg de poids vif. Dans un premier essai, trois niveaux énergétiques ont été comparés chez les brebis allaitant un agneau. Le niveau ajusté (A, 8 brebis) a été apporté pour assurer un gain moyen quotidien (GMQ) théorique de 250 g$\cdot$j$^{-1}$. Les niveaux bas (B, 8 brebis) et haut (H, 8 brebis) représentaient 75 et 150 % de A, respectivement. Dans un deuxième essai, un gradient de besoins a été testé chez les brebis recevant la ration H, à portée simple (S, mêmes brebis que celles de l'essai1), double (D, 8 brebis) et triple (T, 6 brebis). Le schéma expérimental a été répété lors d'une deuxième saison de mise-bas. Les animaux recevaient ad libitum du foin de Digitaria decumbens (0,6 UFL, 4,6 % MAT). Le concentré était composé de maïs (65 % ), de farine de soja (3 % ), de farine de poisson (8 % ) et de luzerne déshydratée (24 % ). La production laitière (PL) des brebis recevant la ration B a été plus faible ($P < 0,05$) que celle des brebis des lots A et H : 1142, 1415 et 1718 g$\cdot$j$^{-1}$, respectivement. Les notes d'état corporel (NEC) ont diminué, stagné et augmenté pour les brebis des lots B, A et H, respectivement. Le GMQ des agneaux simples a été peu différent entre les rations et a atteint au maximum 248 g pour le lot H. La PL des brebis de taille de portée multiple a été supérieure de 30 % à celle des brebis à portée simple. Le GMQ des portées doubles a été voisin de 400 g. Des recommandations sont formulées dans le cas d'un élevage intensif : 1,47 et 2,17 UFL$\cdot$j$^{-1}$ pour des brebis pesant près de 50 kg et allaitant respectivement un et deux agneaux.

National audience

International audience

Diplôme : Rapport

International audience

International audience