Made available in DSpace on 2014-12-17T15:01:43Z (GMT). No. of bitstreams: 1 LibertalamarBS.pdf: 1245835 bytes, checksum: e50b7694a4b730a50be93e5d2ce30412 (MD5) Previous issue date: 2007-06-01 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / Stabilization ponds are an effective sewage treatment alternative for the climatic conditions prevailing in Brazil. In the present work, a primary facultative pond was studied, in the city of Natal, Rio Grande do Norte, Northeast Brazil. The aim of this study was to evaluate the sedimentation dynamics in the facultative pond. The pond was divided in three section or zones along its length starting from the inlet end namely A1, A2 and A3. The research was accomplished in three phases. In the first the mapping of the sludge layer was done, sludge core samples were also collected for analysis for total, fixed and volatile solids and the depth of the sludge layer was determined using a portable echo sounder. In the second solids sedimentation rates were measured using traps placed in the inlet and outlet zones and in the third phase resuspension sludge was evaluate using a tracer. The amount accumulated sludge since the start operation was 13.583 m3. The sedimentation constant averages changed between 0.93 to 2.94 and 3.90 to 5.80 for the depths of 0.5 and 1.0 m respectively. The relationship between volatile and fixed solids (SV/SF) increased along the pond. The removal efficiencies were 52.12%, 36.09%, and 37.50% for BOD, COD and SS, respectively. The sludge accumulation model proposed had a good adjustment with 0.17 m3/hab.year rate. The results presented here demonstrated that the wind had a direct influence on the sedimentation of solids in this pond affecting the efficiency and sludge accumulation / As lagoas de estabiliza??o s?o alternativas vi?veis para o tratamento de esgoto no Brasil, pelas condi??es clim?ticas. Neste trabalho foi estudada uma lagoa facultativa prim?ria, na cidade do Natal, estado do Rio Grande do Norte. O objetivo do estudo foi avaliar a din?mica de sedimenta??o. A lagoa foi dividida em tr?s se??es ao longo de sua extens?o denominadas A1, A2 e A3 e o estudo foi dividido em tr?s fases. Na primeira foram feitos o mapeamento da camada de lodo, caracteriza??o do lodo e a determina??o da espessura por batimetria. Na segunda, a taxa de sedimenta??o de s?lidos foi determinada usando armadilhas suspensas verticalmente na coluna de ?gua a 50 cm e 100 cm de profundidade. Na terceira fase a re-suspens?o dos s?lidos foi verificada com tra?ador em 10% do volume da lagoa. Amostras de afluente e efluente foram coletadas para an?lise de pH, DBO, DQO e s?lidos suspensos. O volume de lodo acumulado desde o come?o da opera??o do sistema, foi de 13.583 m3. As constantes m?dias de sedimenta??o variaram entre 0,93 a 2,94 e 3,90 a 5,80 para as profundidades de 0,5 e 1 m, respectivamente. A rela??o entre s?lidos vol?teis e fixos (SV/SF) na camada de lodo aumentou ao longo da lagoa. As efici?ncias de remo??o foram de 52,09 %, 36,12%, 37,50 % para DBO, DQO e SST, respectivamente. A taxa de ac?mulo de lodo foi estimada em 0,17 m3. hab-1.ano-1 e o modelo matem?tico proposto conseguiu estimar de forma satisfat?ria o volume de lodo depositado. Os resultados mostram que a dire??o e a velocidade do vento tem uma influ?ncia direta na sedimenta??o dos s?lidos nesta lagoa afetando a efici?ncia e o ac?mulo de lodo

In a collaboration with limnologists at Uppsala University a planar HPGe detector has been used to find 210Pb in lake bottom sediment in hopes of getting an estimation for the sedimentation rate. Using a least squares fit to the data, the sedimentation rate was calculated to 0.08 ± 0.01 cm/year with background subtraction, and with it a timescale for the age of the sediment could be implemented. With this timescale the lake bottom sediment can be dated as far back as a century. Along with this, using 137Cs traces from the Chernobyl disaster of 1986 a consistency check can be made for our timescale. It is estimated that the Chernobyl disaster occurred at 1989 ± 7 years which is consistent with reality since 1986 is included in the interval 1982-1989. This helps us validate the determined sedimentation rates.

De par sa position, le Golfe du Lion est un site idéal pour l’investigation des changements paléo-environnementaux et des processus affectant le dépôt sédimentaire. Les travaux antérieurs ont permis de mettre en évidence les impacts de la variabilité climatique et glacioeustatique sur l’organisation stratigraphique de la marge, mais également sur les exports terrestres de matière organique.L’étude isotopique du carbone organique et de l’azote de la matière organique dans les sédiments du forage PRGL1-4 nous a permis de mettre en évidence de forts exports fluviaux lors des interstades survenus au cours des 200 000 derniers milles ans. La mise en regard de cette découverte avec les enregistrements paléo-climatologiques terrestre et marin disponibles dans la région indique que ces forts exports fluviaux résultent d’une augmentation des précipitations le long de la bordure Nord Méditerranéenne. Grâce à la position dePRGL1-4, nous proposons que ces pluies soient le résultat d’une augmentation du passage de dépressions Nord Atlantique dans le bassin Ouest Méditerranéen.Une caractérisation des isotopes du soufre préservés dans la pyrite sédimentaire a été réalisée. Les résultats obtenus ont permis de mettre en évidence une variation isotopique insoupçonnée, l’une des plus grandes observées de nos jours, dont la cyclicité semble indiquer un fort contrôle climatique. Nous proposons deux mécanismes influençant le fractionnement isotopique: une modulation de l’activité bactérienne par le climat, et/ou (ii) une modulation locale liée la nature des sédiments impliqués dans la formation des pyrites en lien avec les variations eustatiques. / By its position, the Gulf of Lion is an ideal location for investigation of past ecological changes and processes affecting the sedimentary deposition. Previous work has highlighted the impacts of climatic and glacio-eustatic changes on the GoL stratigraphic organization, but also on terrestrial exports of organic matter.This isotopic study based on the organic carbon and nitrogen preserved in PRGL1-4 sediments highlights important rivers runoff during warm periods of the last 200 000 years.Regional intercomparison with terrestrial and marine records indicates that these river exports resulting from an increase of precipitation over the North Mediterranean borderland.Using PRGL1-4 location, out of Mediterranean cyclogenetic area, we suggest that these pluvial events occurred in response to enhance passage of North Atlantic atmospheric perturbation into the Western Mediterranean basin.Pyrite sulfur isotopes investigations over the last 500 kyr have also been done. The stratigraphic variations (up to 76‰) in the isotopic data reported here are among the largest ever observed in pyrite, and are in phase with glacial-interglacial sea level. These results suggest that there exist important but previously overlooked depositional controls on sedimentary sulfur isotope records. Two different mechanisms influencing the isotopic fractionation can explain the observed dataset: a climatic modulation of the bacterial activity, and / or (ii) a local sedimentary modulation involve during early diagenetic formation of pyrite in relation with the eustatic variations.