Sustainable use of low flow reaches downstream energy generation dams

The paper describes the issues of water quality in low flow reaches downstream energy generation dams. These reaches should maintain a minimum water flow in order to guarantee adequate ecological conditions in the water body. A case study is presented with respect to the longest low flow reach in Brazil, focusing mainly on environmental and regulatory aspects. Water quality in this reach should be enhanced by the construction of some intermediate dikes, which will allow the sedimentation of particulate matter and the formation of small reservoirs for the growth of aquatic species. A concern remains only with phosphorus concentrations, since the environment will change from a lotic to a lentic condition

Possible water uses in mining lakes: case study of Aguas Claras, Brazil

The paper presents a Brazilian experience related with the decommissioning of an exhausted mining activity and the consequent formation of a pit lake. This water body, which is still in a process of filling, will reach the final depth of 234 m, being hence the deepest lake in the country. Since 2001 (first year of formation) the water quality has been monitored on a monthly basis. The aquatic environment is absolutely free from contamination and presents an excellent water quality. There is a marked shift in the dominance of algae groups, probably due to this early stage of creation of a new ecosystem. Some conflicts are now arising regarding the possible water uses. The high water quality allows a sound utilization for urban supply, but the manifestations of the population (through public hearings) is towards the utilization of the lake for recreational purposes and landscape harmony. The paper discusses the origin and possible solutions for these conflicts

Restoration of Lake Pampulha, Brazil by using sanitation and in-lake techniques

The paper presents a broad view about the measures for restoration of Lake Pampulha, Brazil. This man made reservoir is located in a dense inhabited urban area and constitutes the main touristic attraction of the city of Belo Horizonte. Since several decades the water body receives the discharge of untreated sewage from domestic as well from industrial sources, what leads to severe episodes of algal blooms in the water surface. In order to combat this eutrophication problem some measures have been already carried out and others are planned in a short term. These preventive and corrective techniques provides an efficient association between sanitation processes and the application of in-lake treatment actions. Moreover a hydrodynamic modelling has been also carried out with the purpose of evaluating the water circulation and the water residence time in the compartments of the lake

Influence of climatic conditions on cyanobacteria blooms in a tropical water supply river (Rio das Velhas, Brazil)

The paper presents a discussion about the striking influence of climatic conditions on the onset of cyanobacteria blooms in a warm water river in Brazil. An unusual drought period has been observed in the second half of 2007 in Rio das Velhas, Brazil, which led to an unexpected bloom of bluegreen algae (cyanobacteria). Cyanobacteria blooms constitute a special concern in Brazil, since the first human deaths caused worldwide by cyanotoxins have been reported in this country. The Brazilian legal framework restricts the water abstraction under such conditions and imposes a special monitoring programme to be carried out by water supply companies. The results of water quality analysis point out the conjunction of two factors as the main cause of the mentioned cyanobacteria blooms: nutrients input from treated and untreated sewage as well from diffuse sources and the extended dry period in 2007

Cyanobacteria in water supply reservoirs and strategies for their control

The paper describes the problems related with eutrophication in water supply reservoirs. One of the most relevant impacts is the growth of cyanobacteria, which are able to generate very powerful toxins. This situation is more critical in tropical regions, where all metabolical processes are faster and where generally there is lack of financial resources for implementation of adequate monitoring programs. A case study(Vargem das Flores Reservoir) is presented, with emphasis on the study of eutrophication development based on N/P relationship. It was found that low N/P values did not favour here the dominance of cyanobacteria, as generally reported in the technical literature. The paper also discusses the adoption of some preventive and corrective techniques for avoiding cyanobacteria blooms in water supply reservoirs

Design and analysis of an urban retention pond database

8 pagesInternational audienceIn conjunction with the urban development in the Ile-de-France region numerous retention ponds were created in the seventies. Because of their number the knowledge concerning the behaviour of these ponds remains quite scarce and it is a weakness for their optimal management. This paper presents a database related to retention ponds in the Ile-de-France region, which gathers all the available data concerning their design, their behaviour in their catchment, their water quality and their maintenance. The objective of this database is precisely to improve their knowledge and to finally help in their management. Data from 55 ponds are presently included in the database. From these data it is possible to infer a high pollution retention potential of the ponds. Despite the heterogeneity of the monitoring strategies, significant relations between the water quality in the ponds and the occupation of the catchment were established.Lors de la création des villes nouvelles en région Ile de France dans les années 70, les bassins de retenue en eau ont été abondamment utilisés pour contrôler l'évacuation des eaux pluviales. Toutefois, en raison de leur nombre, la connaissance du comportement de ces bassins reste limitée, ce qui constitue une faiblesse pour leur gestion optimale. Ce texte présente une base de donnée relative à ces bassins en eau. Elle rassemble toutes les informations disponibles relatives à leur conception, leur fonctionnement, la qualité de leurs eaux et leur entretien. L'objectif de cette base de données est d'améliorer la connaissance de ces plans d'eau et ultérieurement d'aider à leur gestion. Les données de 55 bassins sont actuellement rentrées dans la base de données. A partir de ces données, on peut estimer un potentiel de dépollution élevé. Par ailleurs, des relations significatives entre la qualité des eaux et l'occupation du bassin versant ont été mises en évidence

MÉTODO PARA DETERMINAÇÃO DE RESÍDUOS DE CLORPIRIFÓS EM ALFACE POR CROMATOGRAFIA A LÍQUIDO DE ALTA EFICIÊNCIA

Este trabalho propõe método de análise de resíduos de Clorpirifós em amostras de alface por cromatografia a líquido de alta eficiência (CLAE). A análise foi realizada em cromatógrafo Shimadzu, com detector de ultravioleta ajustado em 229 nm, Coluna C-18, modelo Zorbax ODS (4,6 mm x 25 cm, 5 µm), fluxo de 1 mL/min e temperatura de 35ºC. Usou-se Metanol:Água (82:18) como fase móvel e volume injetado de 50 µL. Amostras de alface (20 g) foram trituradas e homogeneizadas na presença de 50 mL de Diclorometano (DCM). O material foi filtrado a vácuo e evaporado a temperatura de 50ºC. O resíduo foi retomado com fase móvel, agitado, desgaseificado, filtrado em membrana 0,22 µm e injetado no cromatógrafo (injetor automático). Os resultados do teste de repetitividade mostraram recuperação média de 101,91%. O método proposto é simples e rápido para determinação de resíduos de Clorpirifós em amostras de alface. METHOD FOR THE DETERMINATION OF CHLORPIRYFOS RESIDUES IN LETTUCE BY USING HPLC (High Performance Liquid Cromatograph) Abstract This paper suggests a method for the residual analysis of chlorpiryfos in lettuce samples by using HPLC (High Performance Liquid Cromatograph). The analysis has been carried out in a Shimadzu cromatograph, with ultraviolet detector adjusted to 229 nm, column C-18, model Zorbax ODS (4.6 mm x 25 cm, 5 µm), flux 1mL/min, temperature of 350C. The mobile phase used was methanol:water (82:18) and the injected volume of 50 µL. Lettuce samples have been triturated and homogenized in the presence of 50 mL of the solvent Dichlormethan (DCM). The vacuum filtered material was evaporated at the temperature of 500C. The residue has been retaken in a mobile phase, stirred, degasified, filtered in a 0.22 µm membrane and automatically injected in the HPLC. Good results were obtained in a repetitivity test, with an average recovery of 101.91%. The proposed test presents simplicity and quickness in the residual determination of Chlorpiryfos in lettuce samples

Enrichment of anaerobic ammonium oxidizing bacteria - anammox

Bactérias anaeróbias oxidadoras de amônia (bactérias Anammox, do inglês anaerobic ammonium oxidizing bacteria) foram enriquecidas em reator em batelada sequencial (RBS), a partir de lodo proveniente de um sistema convencional de lodos ativados tratando esgoto doméstico de Belo Horizonte (MG). Após três meses de cultivo, atividade Anammox foi detectada no sistema pelo consumo de quantidades estequiométricas de NO2- e NH4+. Análises de hibridação in situ fluorescente (FISH, do inglês fluorescent in situ hybridization) confirmaram a presença de bactérias Anammox, provavelmente Candidatus Brocadia anammoxidans, e revelaram que estas representavam 53% do total de células (após 6 meses de cultivo). O desempenho do reator ao longo dos sete meses de operação demonstrou remoção quase que total de nitrito, baseada em concentração afluente de 61 a 95 mg N-NO2-/L. A eficiência máxima de remoção de amônia alcançada foi de 95%, a partir de concentração afluente de 55 a 82 mg N-NH4+/L.Anaerobic ammonium-oxidizing (Anammox) bacteria were enriched from sludge collected at a conventional activated sludge system treating domestic wastewater of Belo Horizonte(MG), Brazil, employing a sequencing batch reactor (SBR). After three months of cultivation, Anammox activity was detected in the system by the consumption of stoichiometric amounts of NO2- and NH4+. Fluorescent in situ hybridization (FISH) results revealed the presence of Anammox bacteria (probably Candidatus Brocadia anammoxidans) and showed that they accounted for 53% of the total bacterial population (after 6 months of cultivation). The reactor performance during the seven months of operation showed a near perfect removal of nitrite, based on the influent NO2--N concentration of 61-95 mg/L. The maximum ammonia removal efficiency was 95% from the influent N-NH4+ concentration of 55-82 mg/L.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)(FAPEMIG) Fundação de Amparo à Pesquisa de Minas GeraisFine

Dinamic of pathogenic protozoa and cyanobacteria in a reservoir used for water supply in southeastern Brazil

O presente estudo foi baseado no monitoramento de um reservatório tropical (Vargem das Flores) utilizado para o abastecimento público de água de sete cidades da região metropolitana de Belo Horizonte, Minas Gerais. O reservatório foi monitorado durante quatro anos: período inicial (de 2004 a 2007) para células de cianobactérias e parâmetros físico-químicos e, subsequentemente (2007 e 2008), para oocistos de Cryptosporidium spp. e cistos de Giardia spp. em quatro estações de amostragem. Também foram avaliadas as concentrações de Escherichia coli de 2007 a 2008, o que permitiu a caracterização de cada ponto de amostragem de acordo com a legislação do Conselho Nacional do Meio Ambiente (CONAMA) nº 274/2000. Os resultados indicaram concentrações de (oo)cistos de Cryptosporidium spp. e Giardia spp. variando de 0 a 0,8 (oo)cistos.L-1, e as mais elevadas concentrações de células de cianobactérias, de 0,0 a 4,5 x 105 cels.mL-1, apontando assim para potencial risco à saúde humana caso a água do reservatório seja consumida sem tramento. As cianobactérias não foram encontradas durante a estação seca. O grupo retornou rapidamente após a desestratificação. A estação chuvosa foi caracterizada pela elevada ocorrência de cianobactérias com a predominância da espécie picoplanctônica (Aphanocapsa sp.), sobre Microcystis spp. previamente detectada, e apresentou as maiores variações de oxigênio dissolvido, turbidez, fósforo total, ortofosfato, amônia, nitrito e nitrato. A mudança observada no grupo das cianobactérias (Aphanocapsa spp. sobre Microcystis spp.) pode ser um indicativo das alterações das características da água. De acordo com as concentrações de E. coli , as estações foram classificadas como próprias para recreação de contato primário, de acordo com a Resolução CONAMA nº 274/2000.The current study monitored the water quality of a tropical reservoir (Vargem das Flores) used to supply potable water to seven cities in the metropolitan area of Belo Horizonte, Minas Gerais, southeast Brazil. The reservoir was monitored for four years: initially (from 2004 to 2007) for cyanobacterial cells and physicochemical parameters and, subsequently (in 2007 and 2008), for Cryptosporidium spp. oocysts and Giardia spp. cysts in four sampling stations. The concentrations of Escherichia coli were also measured in 2007 and 2008, wich allowed the characterization of each sampling point according to the National Environment Council (CONAMA) no. 274/2000. Results indicated concentrations of Cryptosporidium spp. and Giardia spp. (oo)cysts ranging from 0 to 0.8 (oo)cysts.L-1, and higher concentrations of cyanobacteria cells, from 0.0 to 4.5 x 105 cells.mL-1, thus indicating potential risks to human health, if the water from the reservoir is not properly treated before consumption. The group of cyanobacteria was not found during the dry season, returning soon after destratification. The rainy season was characterized by a higher ocurrence of cyanobacteria and predominance of picoplanktonic species (Aphanocapsa spp.), over the Microcystis spp. previously found and presented the highest variations in dissolved oxygen, turbidity, total phosphorous, orthophosphate, ammonia, nitrite and nitrate. The change observed within the group of cyanobacteria (Aphanocapsa spp. over Microcystis spp.) may be indicative of changing characteristics in the water source. All the sampling points were classified as adequate for primary contact recreation, given the E. coli concentrations, according to the CONAMA Resolution no. 274/2000