Récemment, de nombreuses recherches ont été dévolues à la mise au point de réacteurs biphasiques, perçus comme une nouvelle technologie pour le traitement des polluants organiques dans les effluents gazeux. Ces réacteurs impliquent lutilisation dune seconde phase non aqueuse pour améliorer la solubilité et le transfert de masse des composés hydrophobes. Dans ce travail, nous avons développé un réacteur biphasique agité utilisant lhuile de silicone comme seconde phase. Initialement, Rhodococcus erythropolis T 902.1 a été sélectionné sur base de sa capacité à dégrader lisopropylbenzène (IPB), un composé choisi comme modèle représentatif de la famille du benzène. Deuxièmement, le transfert de masse de loxygène et de lIPB a été étudié en relation avec les conditions hydrodynamiques du réacteur et le type dhuile de silicone. Lutilisation dune proportion de 10 % dhuile de faible viscosité (10cSt) naffecte pas significativement le transfert de masse de loxygène. Cependant la grande solubilité de lIPB dans lhuile de silicone conduit à une forte augmentation du potentiel de transfert, spécialement pour les proportions en huile les plus élevées. Néanmoins, il ne semble pas utile de dépasser une proportion de 10 % car le KLaIPB et le KLaO2 diminuent drastiquement pour des proportions supérieures. Lexistence dune concentration optimale en élément biotique apparaît également. En effet, les concentrations optimales en biomasse (B) et extrait surfactant (ES) peuvent être évaluées à, respectivement 0,5 g/L et 0,7 g/L, elles assurent une valeur maximale du coefficient global de transfert de masse de loxygène (KLaO2). Plus spécifiquement, lES augmente laire interfaciale « a » en diminuant le diamètre des bulles tandis que la biomasse la diminue dès quune concentration de 1 g/L est atteinte. Au contraire, lES agit négativement sur le KL tandis que la biomasse laméliore globalement. En terme de performance, il est clairement montré que la taux de biodégradation de lIPB est davantage corrélé au débit gazeux de leffluent quà la concentration en polluant. Le réacteur biphasique a été suivi sur une période de 38 jours afin de caractériser son comportement à moyen terme pour différentes conditions opératoires. Lors dune phase dalimentation transitoire (10h/j), la capacité moyenne délimination est denviron 240 g/m3 pour une charge massique de 390 g/m3. Finalement, une approche originale a été développée en utilisant un bioréacteur de type scale-down pour reproduire les conditions hydrodynamiques rencontrées dans les réacteurs industriels. Il est clairement démontré que le polluant (IPB) affecte négativement lextrapolation en augmentant la vitesse de séparation de phase. Cependant cet impact négatif est largement compensé par la présence déléments biotiques qui stabilise fortement le système biphasique, rendant totalement envisageable lextrapolation à grande échelle. En conclusion, lutilisation dun réacteur biphasique eau-huile de silicone pour lélimination de concentrations élevées (~ 6g/m3) en polluants hydrophobes est adéquate. Le réacteur proposé présente de réelles opportunités pour le traitement biologique deffluents pollués par des composés hydrophobes. Son utilisation pourrait être envisagée lorsque loxydation thermique savère trop onéreuse ou lorsque les biofiltres classiques atteignent leurs limites ( >1 g/Nm3 et une charge volumique de 90m3/m3.h.)./Recently, a lot of research has been devoted to the study of two-phase partitioning bioreactors (TPPB) as new technology for xenobiotic degradation in gaseous effluents. These reactors involve the use of a second non-aqueous phase to improve the solubility and transfer of hydrophobic compounds. In this work, we have developed a stirred two-phase partitioning bioreactor using silicone oil as second phase. Initially, Rhodococcus erythropolis T 902.1 was selected on the basis of its capacity to metabolize isopropyl-benzene (IPB), used as representative of the benzene-containing compounds. Secondly, the mass transfer of both IPB and oxygen has been considered with relation to their influence on the hydrodynamics of the reactor and the type of silicone oil used. The addition of 10% low viscosity silicone oil (10 cSt) in the reactor does not significantly affect the oxygen transfer rate. The very high solubility of IPB in the silicone oil leads to an enhancement of the driving force term, especially when high proportion of silicone oil are used. However, it is not necessary to use a volume fraction higher than 10% since KLaIPB and KLaO2 decrease sharply at above such proportion. In addition, an optimal concentration appeared to exist for both biotic components, respectively 0,5 g/L and 0,7 g/L for biomass (B) and surfactant extract (SE) when the global mass transfer coefficient (KLa) of oxygen was measured in the TPPB. More specifically, SE improved the interfacial area a by decreasing the bubble diameter, while B reduced it at concentrations up to 1 g/L. In contrast, the SE concentration acted negatively on KL, while it was favoured by the B concentration. In term of performances, it was clearly shown that the biodegradation rate is more directly related to the inlet flow of IPB than to the concentration of IPB in the inlet gas. The TPPB was monitored for 38 days to characterise its behaviour under several operational conditions. During an intermittent loading phase (10 h/day), the average elimination capacity remained above 240 g/m3.h for an average IPB inlet load of 390 g/m3. h. Finaly, an original approach was developed using a scale-down bioreactor allowing to reproduce the hydrodynamics encountered under full scale TPPB. It was clearly shown that the IPB affects negatively the scaling-up of the process by increasing the speed of phase partitioning. However, this negative impact was strongly compensated by the presence of biotic compounds stabilizing the two phase system and rendering the scaling-up process feasible. In conclusion, the use of a water-silicone oil TPPB to remove a high inlet load of IPB was successful. The proposed reactor retains a high potential for the biological treatment of gas effluents polluted by hydrophobic aromatic compounds. The suggested process might be applied in the range of concentration and flow where thermal oxidation is too expensive (between 1 and 7 g/Nm3) or when the biofilters are usually limited, i.e. to treat a polluted effluent concentrated with > 1 g/Nm3 at a flow of 90m3/m3.h.

Les intégrons sont des supports génétiques bactériens de capture, d’expression et de dissémination de gènes de résistance aux antibiotiques sous forme de cassettes. Ils sont majoritairement décrits chez les bactéries à Gram négatif chez qui ils confèrent généralement un phénotype de multirésistance. Les intégrons de résistance (IR) jouent un rôle majeur dans l’acquisition de la résistance dans le monde bactérien. Il existe 3 principales classes d’IR ; les IR de classe 1, les IR de classe 2 et les IR de classe 3 (IR3). Contrairement aux 2 premières classes, les IR3 représentent la classe d’intégrons de résistance la moins étudiée. Très peu de travaux s’intéressent à leur étude et on dénombre actuellement moins de 10 IR3 entièrement caractérisés. Les objectifs de ce travail de thèse étaient (i) d’effectuer une étude épidémiologique des IR3 en France et au Cameroun et (ii) d’étudier les modalités d’expression de l’intégrase et des cassettes de ces intégrons. Nos travaux ont permis d’isoler puis de décrire 3 nouveaux IR3 présents au sein de bactéries environnementales appartenant aux genres Aeromonas, Acinetobacter et Citrobacter. Les cassettes de ces IR3 codent des résistances aux bétalactamines, aminosides et ammoniums quaternaires. De plus, nous avons caractérisé des IR3 dans 3 souches de Delftia spp. (2 D.acidovorans et 1 D. tsuruhatensis) isolées en Afrique ; les cassettes de ces intégrons ne codent pas de résistance aux antibiotiques. L’axe plus fondamental de ce travail de thèse a permis de montrer que le PintI3(1) est le promoteur impliqué dans l’expression du gène intI3. De plus, nous avons montré que les variants du promoteur Pc, ainsi que les variants du promoteur PintI3(1) sont fonctionnels et de force différente. Il ressort de nos travaux que l’environnement constituerait un réservoir d’intégrons de classe 3 et que ces supports génétiques pourraient jouer un rôle important dans la dissémination de la résistance au sein de cet écosystème. / Integrons are bacterial genetic elements able to capture and express genes embedded within gene cassettes. They are widely described among Gram-negative bacteria and generally confer a multidrug resistance phenotype. Resistance integrons (RI) play an important role in the acquisition of antibiotic resistance. There are 3 main classes of RI. Class 3 RI has been poorly studied class with less than ten fully IR3 characterized. Objectives of this thesis were (i) to conduct an epidemiological study of class 3 RI in France and Cameroon and (ii) to better understand the modes of expression of the integrase and cassettes of IR3. We described 3 new class 3 RI isolated from environmental bacteria belonging to genus Aeromonas, Acinetobacter and Citrobacter. Gene cassettes encoded resistance to betalactams, aminoglycosides and quaternary ammonium compounds. We also described IR3 from three Delftia strains (2 D.acidovorans and 1 D.tsuruhatensis) in Africa containing cassettes that do not encode antibiotic resistance. The fundamental part of the work showed that the PintI3(1) promoter is involved in the expression of the intI3 gene. Furthermore, we demonstrated that variants of the Pc promoter and variants of the PintI3(1) promoter are functional with different strengths. These results showed that the environment may constitute a reservoir of class 3 integrons and that these genetic elements could play an important role in the spread of the resistance in this ecosystem.

In model reaction systems to test amino acids in chlorinated waste effluents, several amino acids were chlorinated at high chlorine doses. (2000-4000 mg/1). Amino acids present in municipal waste effluents before and after chlorination were concentrated and purified using cation exchange and Chelex resins. After concentration and cleanup of the samples, the amino acids were derivatized by esterification of the acid functional groups and acylation of the amine groups. Identification and quantification of the amino acids and chlorination products was carried out by gas chromatography/mass spectrometry, using a digital computer data system. Analysis of the waste products revealed the presence of new carbon-chlorine bonded derivatives of the amino acid tyrosine when the effluents were treated with heavy doses of chlorine.

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

O uso agrícola de resíduos de efluentes orgânicos é uma alternativa interessante de disposição, pois permite o aproveitamento potencial das águas e dos nutrientes para o crescimento das plantas. A utilização destes efluentes na agricultura constitui uma importante contribuição para a minimização da contaminação devido à redução de seu lançamento em corpos hídricos, além de se tornar uma alternativa econômica para a propriedade rural, que diminui os custos para aquisição de fertilizantes. O aumento no resíduo de efluente produzido pelas usinas de cana-de-açúcar, a vinhaça, é reflexo do aumento da produção do álcool no Brasil. A vinhaça é um subproduto rico em nutrientes, principalmente em matéria orgânica, característica essa que a torna um grande poluidor quando lançado em corpos hídricos. Dentre as soluções para destinação final da vinhaça, a que se destaca é sua aplicação no solo, por meio da técnica de fertirrigação. Dentro desse contexto, o presente trabalho consiste em avaliar o efeito da aplicação de diferentes doses de vinhaça no crescimento, produção e qualidade dos frutos do cultivar de abacaxi vitória, visando à disposição final deste efluente de forma a garantir a reciclagem de água e nutrientes, sem comprometimento das características químicas e físicas do solo. O experimento foi conduzido na área experimental do Departamento de Engenharia de Biossistemas da Escola Superior de Agricultura \"Luiz de Queiroz\" (ESALQ/USP) em ambiente protegido (casa de vegetação). Adotou-se delineamento inteiramente aleatorizado com 5 tratamentos e 4 repetições, totalizando 20 parcelas experimentais, sendo a unidade experimental representada por trincheiras com dimensões 3,20 m de comprimento por 0,80 m de largura por 0,40 m de profundidade. Os tratamentos foram formados pela aplicação de doses de vinhaça referentes a 0, 50, 75, 100 e 125% da demanda de 462 kg ha-1 de potássio pelo abacaxizeiro. O potássio foi tomado como elemento de referência para obtenção dos volumes de vinhaça, sendo que para os cálculos de volume, utilizou-se a norma CETESB P4.231. As fertirrigações foram ministradas, via gotejamento, de acordo com a demanda nutricional do abacaxizeiro, respeitando suas fases de desenvolvimento. Verificou-se que a aplicação de vinhaça no solo aumentou a CTC e a matéria orgânica, porém não promoveu alterações nas características físicas. O aumento das doses de vinhaça afetaram diretamente as variáveis biométricas: altura de plantas, número de folhas, comprimento e largura da folha \"D\". A área foliar, matéria seca da parte aérea e raiz sofreram influência positiva do aumento das doses de vinhaça aplicadas. Verificou-se que as maiores concentrações de nitrato e potássio na solução do solo foram encontradas nos tratamentos com maiores doses de vinhaça aplicadas. Os tratamentos fertirrigados com vinhaça apresentaram menor produtividade quando comparados ao tratamento com adubação química, no entanto as plantas que foram fertirrigadas apresentaram frutos com qualidades físico-químicas superiores, apesar de na análise sensorial não ter sido verificado diferença significativa entre os tratamentos. / The using of effluent residues in agriculture it is a good alternative because allows the use of the water and the nutrients to cultivate some crops. Also it is an important contribution with the mitigation of the contamination promoted by these effluents when disposed in a hydric system and could be an economic alternative to reduce costs with fertilizers. The increase in the production of effluent in the sugarcane mill, the vinasse, it is the result of the increase in the production of ethanol. The vinasse it is a residue rich in nutrients, mainly organic material that can be a problem when disposed in the hydric systems. One alternative to solve this problem it is to utilize the vinasse in the soil by fertigation. This study aim to evaluate the growing, yield and fruit quality in pineapple variety vitória with different levels of vinasse applied by fertigation, and the recycling of water and nutrients by vinasse without compromise the chemical and physical soil characteristics. The experiment was conduct in a greenhouse located in the Biossystem Engineering department, college of agriculture \"Luiz de Queiroz\" ESALQ/USP. The experimental design adopted was completely randomly with 5 treatments and 4 replications, being the experimental unit one trench with 3.2 of length, 0.8 m of width and 0.4 m depth. The treatments was composed by different levels of vinasse: 0, 50, 75, 100 and 125% of the total pineapple potash necessity (462 kg ha-1). The potassium was used as reference element to obtain the total volume of vinasse and was used the standard CETESB P4.261. The fertigation was applied by drip irrigation and respected the pineapple nutrient requirement in the different development phases. The vinasse application promoted the increase in the soil cation-exchange capacity (CEC) and organic material, but not changed their physical characteristics. The increment in the vinasse levels effected directly the biometrics variables: plant high, number of leaves, length and width of leaf \"D\". The leaf area, dry material of aerial part and root showing positive correlation with the vinasse levels applied. The higher level of nitrate and potash in the soil solution was observed in the treatments that received the higher levels of vinasse. Treatments that receive vinasse by fertigation presented lesser yield when compare to treatments that receive just chemical fertilization, but fruits with better physic-chemicals quality, although sensory analysis have not been verified significant difference between treatments.

A crescente competição pelo uso da água entre diversos setores da sociedade e a escassez potencial dos recursos hídricos torna desejável o reuso de águas residuárias, principalmente no setor agrícola, o maior consumidor de água. A utilização de efluentes de esgoto tratado (EET) na irrigação tem sido uma alternativa popular e atrativa, com triplo propósito: tratamento complementar do efluente, fonte de água e fonte de nutrientes ao sistema solo-planta. Entretanto, no Brasil ainda há pouca tradição na utilização de EET na agricultura e carência de pesquisas relacionadas ao tema. O presente trabalho teve como objetivo caracterizar os EETs de duas estações de tratamento do município de Piracicaba-SP (ETE-Piracicamirim e ETE-Cecap), em diferentes épocas do ano (períodos seco e chuvoso). Também foi objetivo desse estudo identificar procedimentos eficientes de estabilização química das amostras, bem como estabelecer técnicas analíticas adequadas para cada espécie química de interesse. Os efluentes foram caracterizados quimicamente, empregando-se diferentes técnicas analíticas (AAS, Fia, IC, ICP-OES) para a determinação das seguintes espécies químicas: Ca2+, Mg2+, K+, Na+, NH4+, SO42-, Cl-, NO3-. A condutividade elétrica, o pH e a alcalinidade também foram avaliados. Ainda foi verificada a estabilidade das amostras em diferentes tempos de armazenagem, utilizando um conjunto de amostras coletadas especificamente para essa finalidade. Os procedimentos de preparação e armazenagem mostraram-se eficientes por até 12 meses, para os íons NH4+, Cl- e SO42- e por até seis meses para o NO3-, indicando que o procedimento pode ser adotado. Apesar de terem sido observadas diferenças nas características químicas dos efluentes entre as estações de tratamento, bem como entre as épocas do ano avaliadas, a constituição química encontrada em ambas encontra-se nas faixas de concentração adequadas para o uso como fertirrigação, proporcionando dessa forma, benefícios econômicos e ambientais. A escolha, tanto da técnica, como dos protocolos analíticos a serem empregados para caracterização química de EETs, deve considerar o custo analítico envolvido, a precisão e a exatidão requeridas para caracterização de cada espécie química / The increasing competition for the use of water among several sectors of the society and the potential shortage of hydric resources indicate a desirable reuse of residual waters mainly in the agricultural sector which is the largest water consumer. The use of effluents from treated sewage (EET) for irrigation has been a popular and attractive alternative, with triple purpose: complementary treatment of the effluent, source of water and source of nutrients to the soil-plant system. However, in Brazil there is still little tradition in the use of EET in the agriculture and lack of researches related to the theme. The main goal of the present study was to characterize EET\'s from two sewage treatment plants in the city of Piracicaba-SP (ETE-Piracicamirim and ETE-Cecap), in different periods of the year (dry and rainy seasons). Beyond that, to identify appropriate analytical technique procedures for each chemical species of interest and to establish efficient procedures for sample chemical stabilization was also objectives of this work. The effluents were chemically characterized using different analytical techniques (AAS, Fia, IC, ICP-OES) in order to determine the following chemical species: Ca2+, Mg2+, K+, Na+, NH4+, SO42-, Cl-, NO3-. The electrical conductivity, the pH and the alkalinity were also evaluated. The chemicals stability within the samples was also verified on different storage periods using samples samples collected specifically for this procedure. The employed procedures for sample preparation and the storage were adequate for NH4+ Cl- and SO42- up to 12 months and for NO3- up to 6 months therefore, being appropriate for this type of sample storage. Despite the chemical characteristics differences observed between the treatment plant for the effluents and the differences between the periods of the year for each treatment plant, the chemical characteristicas are within proper concentration range for agricultural irrigation for both stations thus providing economical and environmental benefits. The choice of both the technique and the analytical protocols to be used for chemical characterization of EETs should take under consideration the involved analytical cost, the precision and the accuracy required to characterize each chemical species

A demanda atual por recursos hídricos com quantidade e qualidade exige que todos os efluentes domésticos sejam tratados de maneira adequada para minimizar os impactos ambientais causados no meio ambiente. As estações de tratamento de efluentes domésticos que utilizam sistemas tradicionais de tratamento em muitos casos não conseguem atingir os valores de remoção de poluentes exigidos pelas legislações ambientais e, portanto, processos avançados de tratamento de efluentes devem ser realizados para garantir tal atendimento. No presente trabalho foi realizada a coleta e caracterização físico-química de amostras em diferentes pontos de processo na estação de tratamento de efluentes do Campus Litoral Norte da Universidade Federal do Rio Grande do Sul. O monitoramento foi realizado durante 33 semanas e mostrou que o efluente tratado final da ETE apresentou valores elevados de poluentes como, por exemplo, nitrogênio total Kjeldahl (NTK), amônia e demanda química de oxigênio (DQO), o que impossibilita seu lançamento. O processo de eletrodiálise do efluente tratado da ETE foi realizada em uma planta piloto onde foram realizados 2 diferentes tipos de ensaios de eletrodiálise. No 1º ensaio o objetivo era avaliar o transporte iônico de poluentes do efluente após a eletrodiálise e os resultados encontrados mostram que, o efluente tratado por eletrodiálise, foram encontrados valores de concentração média abaixo de 1 mg/L para os ânions fluoreto, cloreto, nitrito e nitrato e para os cátions sódio, amônio, potássio e magnésio. Os resultados encontrados na caracterização fisico-química do efluente tratado indicam que o mesmo pode ser utilizado como água de reúso na agricultura, para fins urbanos e na psicicultura se for realizada a correção do pH. O 2º ensaio tinha como objetivo avaliar o comportamento das membranas através da qualidade do efluente após sucessivas eletrodiálises sem realizar a limpeza do sistema e os resultados encontrados mostram que foram obtidos valores de concentração média abaixo de 10 mg/L para todos os ânions e cátions. Os resultados encontrados pela caracterização fisico-química deste efluente tratado por eletrodiálise indicam que o mesmo pode ser utilizado como água de reúso na agricultura e reúso para fins urbanos se for realizada a correção do pH e a remoção da turbidez do efluente. Para o reúso na psicicultura, além da correção do pH, deve ser realizada a remoção do ânion nitrato para valores inferiores a 5 mg/L. / The current demand for water resources with quantity and quality requires that all domestic effluents must be adequately treated to minimize the environmental impacts caused on the environment. Municipal sewage treatment plants (MSTP) using traditional process in many cases fail to achieve the pollutant removal required by environmental. Therefore, advanced wastewater treatment processes must be carried out to ensure such care. The present work carried out the sampling and characterization samples at different process points from the wastewater treatment plant (WWTP) of Campus Litoral Norte of the Universidade Federal do Rio Grande do Sul. The monitoring was performed during 33 weeks and showed that the final treated effluent of the WWTP showed high values of pollutants such as NTK, ammonia and COD, which makes it impossible to discharge in nature. The process of electrodialysis of the final effluent, after the treatment at the WWTP, was carried out in the pilot plant. Two different electrodialysis tests were carried out. On the first test, the objective was to evaluate the ionic transport of pollutants from the effluent after the electrodialysis and the results found show that the effluent treated were found values of average concentration below 1 mg / L were obtained for fluoride, chloride, nitrite and nitrate anions and for sodium, ammonium, potassium and magnesium cations. The results found by the physicochemical characterization of the effluent indicate that it can be used as reuse water in agriculture, for urban proposes and in pisciculture if the pH correction is performed. In the second test, the objective was to evaluate the behavior of the membranes through the quality of the effluent after successive electrodialysis without cleaning the system. The results obtained in the effluent after the second test showed that mean values below 10 mg/L were obtained for all anions and cations. The results obtained by the physicochemical characterization of the effluent indicates that it can be used as reuse water in agriculture and for urban proposes reuse if the correction of the pH and the removal of the turbidity of the effluent is carried out. For reuse in the pisciculture, besides the correction of the pH, the removal of the nitrate anion should be carried out to values below 5 mg/L.

Com a globalização do mercado, muitas empresas procuraram se modernizar objetivando tornarem-se mais competitivas, com o crescimento industrial os recursos naturais apresentam-se mais escassos levando ao desenvolvimento de leis ambientais cada vez mais rígidas. Os custos envolvidos com o uso dos recursos naturais, têm levado as indústrias a buscarem alternativas a curto e médio prazos para minimizarem estes custos, procurando reduzir os seus impactos ambientais. A busca para um menor consumo de água através de técnicas de reúso e reciclagem nos processos industriais passam a fazer parte do planejamento estratégico de várias empresas, inclusive das rolamenteiras. O presente trabalho foi desenvolvido com o objetivo de avaliar o potencial de reúso da água da atividade de tamboreamento de rolos cônicos com espessura entre 5 a 8 mm e altura de 6 a 8 mm, sendo uma atividade de suma importância para garantir um padrão de qualidade satisfatório, de forma que as atividades subsequentes sejam efetuadas sem anomalias técnicas, conduzindo à obtenção de um produto final de qualidade. Por não requerer uma água com padrões elevados de qualidade, neste trabalho foi demonstrado o potencial de reúso de efluentes na atividade de tamboreamento, viabilizando-se sobre maneira o objeto deste estudo, onde é possível avaliar os aspectos físicos e químicos antes e após o tratamento da água para futura implantação contínua. / With the globalization of the market, many companies had looked for to be modernized for becoming more competitive. With the industrial growth, natural resources scarcity, and environmental pollution result in the development of more stringent laws. The costs associated with the use of the natural resources are taking the industries to search alternatives of short and long terms to minimize these costs looking for the reduction of its environmental impacts. The searching for reduced water consumption through techniques of reuse and recycling in its processes start to be integrated in the strategic planning of some companies including the bearing industry. The present work has been developed with the objective of evaluating the potential of water reuse in the activity of tumbling conical coils with thickness in the range of 5 to 8 mm, and height of 6 to 8 mm, being an activity of utmost importance to guarantee a satisfactory quality standard, in order that the subsequent activities are effected without anomalies, leading to the attainment of an end product of quality. By not requiring water with high standards of quality, in this work the potential of effluent reuse was demonstrated in the activity of tumbling, making possible to achieve the objective of this study, where it was possible to evaluate water physical and chemical aspects before and after the treatment for future implantation in continue way.

A crescente competição pelo uso da água entre diversos setores da sociedade e a escassez potencial dos recursos hídricos torna desejável o reuso de águas residuárias, principalmente no setor agrícola, o maior consumidor de água. A utilização de efluentes de esgoto tratado (EET) na irrigação tem sido uma alternativa popular e atrativa, com triplo propósito: tratamento complementar do efluente, fonte de água e fonte de nutrientes ao sistema solo-planta. Entretanto, no Brasil ainda há pouca tradição na utilização de EET na agricultura e carência de pesquisas relacionadas ao tema. O presente trabalho teve como objetivo caracterizar os EETs de duas estações de tratamento do município de Piracicaba-SP (ETE-Piracicamirim e ETE-Cecap), em diferentes épocas do ano (períodos seco e chuvoso). Também foi objetivo desse estudo identificar procedimentos eficientes de estabilização química das amostras, bem como estabelecer técnicas analíticas adequadas para cada espécie química de interesse. Os efluentes foram caracterizados quimicamente, empregando-se diferentes técnicas analíticas (AAS, Fia, IC, ICP-OES) para a determinação das seguintes espécies químicas: Ca2+, Mg2+, K+, Na+, NH4+, SO42-, Cl-, NO3-. A condutividade elétrica, o pH e a alcalinidade também foram avaliados. Ainda foi verificada a estabilidade das amostras em diferentes tempos de armazenagem, utilizando um conjunto de amostras coletadas especificamente para essa finalidade. Os procedimentos de preparação e armazenagem mostraram-se eficientes por até 12 meses, para os íons NH4+, Cl- e SO42- e por até seis meses para o NO3-, indicando que o procedimento pode ser adotado. Apesar de terem sido observadas diferenças nas características químicas dos efluentes entre as estações de tratamento, bem como entre as épocas do ano avaliadas, a constituição química encontrada em ambas encontra-se nas faixas de concentração adequadas para o uso como fertirrigação, proporcionando dessa forma, benefícios econômicos e ambientais. A escolha, tanto da técnica, como dos protocolos analíticos a serem empregados para caracterização química de EETs, deve considerar o custo analítico envolvido, a precisão e a exatidão requeridas para caracterização de cada espécie química / The increasing competition for the use of water among several sectors of the society and the potential shortage of hydric resources indicate a desirable reuse of residual waters mainly in the agricultural sector which is the largest water consumer. The use of effluents from treated sewage (EET) for irrigation has been a popular and attractive alternative, with triple purpose: complementary treatment of the effluent, source of water and source of nutrients to the soil-plant system. However, in Brazil there is still little tradition in the use of EET in the agriculture and lack of researches related to the theme. The main goal of the present study was to characterize EET\'s from two sewage treatment plants in the city of Piracicaba-SP (ETE-Piracicamirim and ETE-Cecap), in different periods of the year (dry and rainy seasons). Beyond that, to identify appropriate analytical technique procedures for each chemical species of interest and to establish efficient procedures for sample chemical stabilization was also objectives of this work. The effluents were chemically characterized using different analytical techniques (AAS, Fia, IC, ICP-OES) in order to determine the following chemical species: Ca2+, Mg2+, K+, Na+, NH4+, SO42-, Cl-, NO3-. The electrical conductivity, the pH and the alkalinity were also evaluated. The chemicals stability within the samples was also verified on different storage periods using samples samples collected specifically for this procedure. The employed procedures for sample preparation and the storage were adequate for NH4+ Cl- and SO42- up to 12 months and for NO3- up to 6 months therefore, being appropriate for this type of sample storage. Despite the chemical characteristics differences observed between the treatment plant for the effluents and the differences between the periods of the year for each treatment plant, the chemical characteristicas are within proper concentration range for agricultural irrigation for both stations thus providing economical and environmental benefits. The choice of both the technique and the analytical protocols to be used for chemical characterization of EETs should take under consideration the involved analytical cost, the precision and the accuracy required to characterize each chemical species

The potential use of sodium propionate as a corrosion inhibitor for mild steel in aqueous media is investigated using a range of electrochemical and surface analytical techniques. The use of sodium propionate for the inhibition of mild steel corrosion is discussed, and the effective pH range of sodium propionate using various buffers is investigated. The effectiveness of sodium propionate as an inhibitor for mild steel pitting corrosion in the presence of various concentrations of CI- is studied. The effect of some oxidants, IO3-, BrO3-, NO32- on the anodic behaviour of mild steel in deaerated 0.01M carboxylate solutions of acetate, propionate, formate, succinate and salicylate is investigated. The critical temperature for effective inhibition of mild steel corrosion with sodium propionate is established, and the chemical composition of the film formed on mild steel surface in sodium propionate solution is studied using surface sensitive Fourier transform infrared spectroscopy FTIR. The efficiency of sodium propionate is compared to that of conventional inhibitors and a mechanism for the inhibition of mild steel corrosion with sodium propionate is proposed. / Doctor of Philosophy (PhD)