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Submitted by Eduarda Figueiredo (eduarda.ffigueiredo@ufpe.br) on 2015-03-11T13:01:47Z No. of bitstreams: 2 TESE_Marilda Nascimento Carvalho_BC.pdf: 2374659 bytes, checksum: 6206ceeb790a2faaa57e74fdae5877af (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) / Made available in DSpace on 2015-03-11T13:01:47Z (GMT). No. of bitstreams: 2 TESE_Marilda Nascimento Carvalho_BC.pdf: 2374659 bytes, checksum: 6206ceeb790a2faaa57e74fdae5877af (MD5) license_rdf: 1232 bytes, checksum: 66e71c371cc565284e70f40736c94386 (MD5) Previous issue date: 2011-02-17 / A contaminação da água por compostos orgânicos tóxicos é uma das maiores preocupações ambientais e tem aumentado o interesse na busca de adsorventes eficientes para a remoção desses compostos. A adsorção utilizando argilas constitui uma das tecnologias de aplicação crescentes empregadas no tratamento secundário de efluentes contaminados por compostos orgânicos de origem na indústria de petróleo. Este trabalho investigou um processo de adsorção dos compostos orgânicos benzeno, tolueno, etilbenzeno, xilenos (BTEX) e do fenol presentes em soluções aquosas em baixas concentrações, até 20 mg/L, por meio de uma argila esmectítica (chocolate) de origem do estado da Paraíba, no nordeste do Brasil, visando colaborar com tecnologias de caráter sustentável, para a indústria de petróleo e petroquímica. A argila organofílica foi sintetizada a partir do sal quaternário (SQA) cloreto de hexadeciltrimetilamônio na concentração de 150% da capacidade de troca catiônica (CTC) da argila, a qual promoveu o aumento do espaçamento basal da estrutura cristalina do argilomineral de 14,73 Å para 22,08 Å. Procedeu-se à avaliação de sistemas de adsorção multicomponente, em regime descontínuo, considerando as abordagens cinéticas e de equilíbrios. Os teores dos componentes BTEX e fenol foram quantificados por cromatografia líquida de alta eficiência (CLAE). Os resultados experimentais ajustaram-se bem ao modelo de equilíbrio combinado de Langmuir-Freundlich e revelaram capacidades máximas de adsorção entre 1,27mg/g (tolueno) a 8,28mg/g (fenol) e cinéticas de equilíbrio em torno de 30 minutos. Parâmetros relacionados à heterogeneidade superficial da argila indicaram a existência de sítios ativos específicos. As afinidades de adsorção de BTEX e de fenol pela argila organofílica no sistema multicomponente apresentaram-se na ordem decrescente: etilbenzeno > xilenos > tolueno > fenol > benzeno. Estas afinidades estiveram relacionadas ao tamanho das moléculas dos aromáticos. As eficiências de remoção obtidas variaram em torno de 55% e 90%.

Due to the toxicity and prevalence of BTEX contaminants (benzene, toluene, ethylbenzene, and xylenes) at hazardous waste sites, approaches for their remediation are of interest, especially those that particularly address benzene, which is often the limiting factor for achieving regulatory cleanup at these contaminated sites. In situ chemical oxidation (ISCO) is a viable technology for BTEX destruction, and hydrogen peroxide and sodium persulfate are two oxidants of interest for BTEX treatment.Laboratory studies were conducted to compare BTEX contaminant destruction and oxidant persistence for these two oxidants and for varied methods of oxidant activation/propagation. Additionally, studies were performed to compare contaminant destruction and oxidant persistence in laboratory contaminant spike systems vs. field site contaminant systems. Finally, contaminant destruction and oxidant persistence in field porous media with varied characteristics were evaluated. Contaminant and oxidant concentrations were measured at multiple time points over a three-week reaction period in each oxidant and oxidant activation/propagation system.Under the comparable conditions evaluated here, sodium persulfate systems demonstrated greater BTEX contaminant destruction and greater oxidant persistence than hydrogen peroxide systems. FeSO4 and citric acid activation of sodium persulfate resulted in greater BTEX destruction and greater oxidant persistence than pH adjustment or hydrogen peroxide activation in both laboratory contaminant spike systems and field gas condensate systems. Additionally, results indicate that the response of the contaminant(s) and oxidant (extent and rate of depletion) are both contaminant-and porous media type-dependent.

Methanol (MeOH) is a common external carbon source for wastewater denitrification, because of its low cost and low sludge yield. Ethanol (EtOH), on the other hand, is more expensive, but yields higher denitrification rates. This study introduces gasoline-denatured ethanol (dEtOH), which is now being produced in large quantities for the production of E10 gasoline, as an alternative carbon source. The gasoline added, as the denaturant, is known as "straight-run" gasoline; a lower grade material that contains mostly aliphatic compounds, but lacks the components that normally boost the octane rating, such as benzene, toluene, ethylbenzene and xylenes (BTEX). Herein are presented the results of using dEtOH, EtOH (95.5% ethanol-4.5% water) and MeOH for denitrification in lab-scale, sequencing batch reactors (SBRs). We also focused on the quantification of BTEX present in dEtOH solution and the inhibition potential of these compounds on both nitrification and denitrification. BTEX content in the dEtOH solution had low and consistent concentration. Ethylbenzene and o-xylene were not detected in the reactor. The removal rates of benzene, toluene and m-xylene were 3.1°1.4, 3.4°1.9 and 0.6°0.4 ?g/L·h, respectively. BTEX were not detected in the effluent and did not inhibit nitrification and denitrification. The denaturant did not affect biomass production or the settling properties of the sludge. The yield (COD/NOx-N) and denitrification rates of dEtOH were similar to those of EtOH and higher than those of MeOH. The cost of dEtOH ($0.91//lb NO??-N removed) is slightly higher than that of methanol ($0.74/lb NO??-N removed). Using dEtOH as an external carbon source is, therefore, very promising and utilities will have to decide if it is worth paying a little extra to take advantage of dEtOH's benefits. / Master of Science

Currently, the application of bioremediation requires extensive and costly monitoring due to limited understanding of the terminal electron accepting processes (TEAPs) that control biodegradation, which impairs the accurate quantification of contaminant mass loss. The measurement of redox conditions and evaluation of TEAPs are critical in assessing the capacity for bioremediation at any site. A series of batch microcosm experiments, using sediment collected from a gasoline-contaminated aquifer at Fort McCoy, Wisconsin, was designed to: 1) evaluate the role of Fe(III) in the development of TEAPs during biodegradation of benzene, toluene, ethylbenzene, and the xylenes (BTEX); 2) examine the biodegradation potential in different portions of the plume; and 3) compare methods of TEAP characterization. In general, the presence of Fe-oxides in microcosms inhibited methanogenesis. Although Fe-reducers did not actively degrade BTEX, Fe-reduction did occur, and most probable number (MPN) counts showed that added Fe(III) increased numbers of Fe-reducers in the microcosms. Methane production in microcosms constructed from sediment near the source area was ~5 times lower than levels produced by the mid-plume sediment. No Fe-reduction occurred in microcosms containing sediment from the source area. These results suggest that the source area has much lower biological activity than the mid-plume. TEAP characterization was conducted using a variety of methods, including geochemical indicators, redox dyes, MPN, and hydrogen concentrations. Monitoring of CH4 concentration yielded useful information in delineation of redox processes; Fe(II) monitoring was unreliable as a geochemical indicator. Redox dyes supplied basic information on reducing environments. MPN counts estimated microbial populations in lieu of faulty geochemical indicators, i.e., Fe(II). The measurement of H2 proved to be one of the more simple and reliable methods for TEAP identification. Results of this study indicate that TEAP characterization should include use of multiple methods; relying on geochemical indicators alone is not sufficient. / Master of Science

Um estudo de caso e dois experimentos controlados de campo foram realizados, a fim de avaliar o impacto do etanol nos processos de atenuação natural que atuam em plumas de contaminação em fase dissolvida de gasolina. No estudo de caso, foi monitorada uma pluma de contaminação de E22 (gasolina com 22% de etanol em volume) em Itaguaí (RJ). Os dois experimentos controlados foram realizados no aqüífero de Borden, no Canadá, para estudar plumas de E10 e E95 (gasolinas com 10 e 95% de volume de etanol, respectivamente). Neste caso, foram realizadas injeções dos contaminantes abaixo do nível d\'água, gerando plumas que foram monitoradas. O etanol, em subsuperfície, particiona rapidamente para a água subterrânea, deixando a fase residual, e é transportado com a velocidade da água subterrânea. Os outros compostos orgânicos de gasolina migram com velocidades menores. Benzeno e tolueno apresentam velocidades mais próximas do etanol, enquanto trimetilbezenos e naftalenos são os mais retardados. Estas diferenças de migração dos compostos resultaram na separação espacial entre as plumas ao longo do período monitorado. A maior concentração de etanol detectada foi de 12.762 mg/L, que corresponde a um volume de etanol em água de 1,63%. As baixas concentrações de etanol não evidenciam que ele tenha exercido efeito cosolvente pronunciado na solubilidade dos compostos da gasolina. Os compostos orgânicos apresentaram perdas de massa ao longo do tempo de monitoramento. A biodegradação dos contaminantes foi observada pelo consumo de oxigênio dissolvido e metonogênese. O etanol apresentou a maior diminuição de massa e foi biotransformado mesmo sob condições anóxicas. O composto que apresentou a menos perda de massa foi o benzeno. A maior persistência de benzeno é atribuída à sua velocidade de migração próxima à água subterrânea associada ao efeito de consumo preferencial de receptores de elétrons pelo etanol. No estudo de caso, o desaparecimento de etanol pode estar relacionado à sua alta taxa de biodegradação, fato observado nos experimentos de campo. Entretanto, o efeito cosolvente na pluma, que explicaria o deplecionamento dos compostos mais móveis, como benzeno e tolueno, na pluma não foi comprovado nos experimentos. / A case study and two controlled field experiments were conducted to evaluate the impact of ethanol on the natural attenuation processes affecting dissolved phase of gasoline plumes. The case study was conducted in Itaguaí (RJ) where an E22 (gasoline with 22 % by volume of denatured ethanol) contaminant plume was studied. The controlled field experiments were conducted at the Borden aquifer in Canada to study plumes E10 and E95. In this case, contaminants were injected below the water table and plumes were monitored down gradient. In subsurface, ethanol partitions fastly from the residual phase and is transported with the ground water velocity. The other organic compounds migrate with lower velocities. Benzene and toluene present velocities close to ethanol, while trimethylbenzenes and naphthalene are the most retarded. These transport differences resulted in the spatial separation between the plumes throughout the monitoring period. The highest ethanol concentration detected was 12,762 mg/L, which corresponds to 1.63 % of ethanol volume in water. The ethanol concentrations detected do not support the cosolvency effect on the gasoline constituents of the plumes. The organic compounds presented mass losses throughout the monitoring period. Biodegradation was also demonstrated through dissolved oxygen consumption and methanogenesis. Ethanol presented the highest mass losses and was biotransformed under anoxic conditions. Benzene presented the smallest mass loss. Benzene´s higher persistence is related to the migration close to the ground water velocity and the preferential consumption of electron acceptors by ethanol. In the case study, the disappearance of ethanol can be related to its higher biodegradation rate, which was detected through the field experiments. However, the cosolvent effect in the plume, which would explain the depletion of the most mobile compounds such as benzene and toluene was not observed during the field experiments.

La France est dépendante en gaz naturel dont elle importe 98% de sa consommation. Comme pour plusieurs autres pays (Etats-Unis, Canada, Grande Bretagne, Autriche, Allemagne, etc.), le stockage de gaz est principalement réalisé afin de pallier aux variations saisonnières de consommation. Grâce aux spécificités géologiques de notre territoire, ce stockage se fait essentiellement aux niveaux d’aquifères très profonds (-500 à 1000 mètres). Le gaz naturel contient en majorité du méthane mais également des traces d’autres composés tels que les BTEX (Benzène, Toluène, Ethylbenzène et les trois isomères du Xylène) qui sont connus pour leur toxicité. Ces hydrocarbures monoaromatiques peuvent se solubiliser dans l’eau de formation aux niveaux des interfaces eau/gaz. Leur biodégradation est bien moins rapide en anaérobiose qu’en aérobiose mais un potentiel d’atténuation naturelle des BTEX par les communautés microbiennes indigènes a déjà pu être démontré lors de travaux antérieurs. Cependant, bien que de nombreuses études aient été réalisées sur le sujet, les voies de dégradation anaérobie ne sont que partiellement connues et les connaissances concernant les microorganismes impliqués sont réduites, voire inexistantes. Le développement de biomarqueurs moléculaires in situ doit permettre d’évaluer rapidement le potentiel de dégradation des microorganismes d’un aquifère. Pour atteindre cet objectif, il est indispensable d’acquérir une meilleure compréhension des mécanismes de dégradation et donc, d’isoler les microorganismes impliqués dans la dégradation de ces composés. Au cours de cette étude, des communautés microbiennes provenant d’échantillons d’eau de formation issue de trois aquifères distincts (nommés dans ce travail A, C et D) ont été étudiées à l’aide de trois approches différentes de microbiologie environnementale. L’ensemble de ces résultats ainsi que ceux de la littérature suggèrent l’ubiquité des bactéries sulfato-réductrices à Gram positif tels que les Desulfotomaculum dans les environnements profonds. Les résultats obtenus lors de ce travail de doctorat suggèrent le rôle prépondérant de microorganismes affiliés au genre Desulfotomaculum dans la dégradation des BTEX en aquifères très profonds et représentent une avancée dans la compréhension des phénomènes d’atténuation naturelle des BTEX dans ce type d’environnement. / France is dependent on natural gas and imports 98% of its consumption. Like in many other countries (The United States of America, Canada, Great Britain, Austria, Germany, etc.), gas storage is primarily performed to compensate for seasonal variations in consumption. Geological characteristics of our territory allow to store essentially natural gas into deep aquifers (-500 to 1000 meters). Natural gas contains mostly methane, but also traces of other compounds such as BTEX (Benzene, Toluene, Ethylbenzene and the three isomers of Xylene) which are known to be toxic. These mono-aromatic hydrocarbons are soluble in water. Anaerobic biodegradation is much slower than aerobic processes however potential for anaerobic BTEX natural attenuation by indigenous microbial communities has already been shown previously. Although many studies have been done on the topic, the anaerobic degradation pathways are only partially known and the knowledge of microorganisms involved is low or nonexistent. The development of in situ molecular biomarkers will allow rapid evaluation of the potential degradation of aquifer microorganisms. To achieve this goal, a better understanding of the mechanisms of degradation is crucial and requires isolation of microorganisms involved in the degradation of these compounds. In this study, microbial communities sampled from formation waters of three distinct aquifers (named in this work A, C and D) were studied using three different environmental microbiology approaches. All these results and those from the literature suggest the ubiquity of sulfate-reducing bacteria such as Gram positive Desulfotomaculum in deep environments. The results obtained during this PhD suggest the importance of microorganisms related to the genus Desulfotomaculum in BTEX degradation in deep aquifers. This work represents a step forward in understanding the phenomenon of natural attenuation of BTEX in this kind of environment.

Made available in DSpace on 2014-12-17T14:08:47Z (GMT). No. of bitstreams: 1 VerushkaSML_DISSERT.pdf: 2610302 bytes, checksum: 15f9dcee57e4dd025cfdc5dd4c655a36 (MD5) Previous issue date: 2011-08-02 / Among the different types of pollutants typically attributed to human activities, the petroleum products are one of the most important because of its toxic potential. This toxicity is attributed to the presence of substances such as benzene and its derivatives are very toxic to the central nervous system of man, with chronic toxicity, even in small concentrations. The area chosen for study was the city of Natal, capital of Rio Grande do Norte, where samples were collected in six different areas in the city, comprising 10 wells located in the urban area, being carried out in three distinct periods March/2009, December / June/2010 and 2009, and were evaluated for contamination by volatile hydrocarbons (BTEX - benzene, toluene, ethylbenzene and xylenes), so this work aimed to assess the quality of groundwater wells that supply funding for public supply and trade in the urban area of the city of Natal, in Rio Grande do Norte, contributing to the environmental assessment of the municipality. The analysis of BTEX in water was performed according to EPA Method 8021b. Was used the technique of headspace (TriPlus TP100) coupled to high resolution gas chromatography with selective photoionization detector (PID) and flame ionization (FID) - model Trace GC Ultra, Thermo Electron Corporation brand. The procedure adopted allowed the detection of concentrations of the order of μg.L-1. Data analysis with respect to BTEX in groundwater in the area monitored so far, shows that water quality is still preserved, because it exceeds the limits imposed by the potability Resolution CONAMA N?. 396, April 2008 / Dentre os diferentes tipos de poluentes tipicamente atribu?dos ?s atividades humanas, os produtos de petr?leo s?o um dos mais relevantes em raz?o de seu potencial t?xico. Esta toxicidade ? atribu?da ? presen?a de subst?ncias como benzeno e seus derivados que s?o muito t?xicos ao sistema nervoso central do homem, apresentando toxicidade cr?nica, mesmo em pequenas concentra??es. A ?rea escolhida para estudo foi o munic?pio de Natal, capital do estado do Rio Grande do Norte, onde foram coletadas amostras em 6 diferentes zonas no munic?pio, compreendendo 10 po?os localizados na zona urbana, sendo realizadas em 3 per?odos distintos mar?o/2009, dezembro/2009 e junho/2010; e foram avaliadas a contamina??o por hidrocarbonetos vol?teis (BTEX benzeno, tolueno, etilbenzeno e os xilenos), portanto este trabalho, teve como principal objetivo, avaliar a qualidade das ?guas subterr?neas que abastecem alguns po?os de capta??o destinados ao abastecimento p?blico e comercial, na regi?o urbana do munic?pio de Natal, no Estado do Rio Grande do Norte, contribuindo para o diagn?stico ambiental do munic?pio. A an?lise de BTEX em ?gua foi realizada de acordo com o m?todo EPA 8021b. Foi utilizada a t?cnica de headspace (TriPlus TP100) acoplado ? cromatografia gasosa de alta resolu??o com detector seletivo de fotoioniza??o (PID) e ioniza??o em chama (FID) - modelo Trace GC Ultra, marca Thermo Electron Corporation. O procedimento adotado permitiu a detec??o de concentra??es da ordem de μg.L-1. A an?lise dos dados com rela??o aos BTEX nas ?guas subterr?neas, no dom?nio monitorado at? este momento, mostra que a qualidade da ?gua ainda est? preservada, pois n?o ultrapassa os limites de potabilidade impostos pela Resolu??o CONAMA n? 396 de abril de 2008

Made available in DSpace on 2014-12-17T15:01:23Z (GMT). No. of bitstreams: 1 ZuzileneSE_DISSERT.pdf: 1395431 bytes, checksum: 1be063abe68213c4ae7025f93618fa6d (MD5) Previous issue date: 2009-12-01 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The oil and petrochemical industry is responsable to generate a large amount of waste and wastewater. Among some efluents, is possible find the benzene, toluene, ethilbenze and isomers of xilenes compounds, known as BTEX. These compounds are very volatily, toxic for environment and potencially cancerigenous in man. Oxidative advanced processes, OAP, are unconventional waste treatment, wich may be apply on treatment and remotion this compounds. Fenton is a type of OAPs, wich uses the Fenton s reactant, hydrogen peroxide and ferrous salt, to promove the organic degradation. While the Photo-Fenton type uses the Fenton s reactant plus UV radiation (ultraviolet). These two types of OAP, according to literature, may be apply on BTEX complex system. This project consists on the consideration of the utilization of technologies Fenton and Photo-Fenton in aqueous solution in concentration of 100 ppm of BTEX, each, on simulation of condition near of petrochemical effluents. Different reactors were used for each type of OAP. For the analyticals results of amount of remotion were used the SPME technique (solid phase microextraction) for extraction in gaseous phase of these analytes and the gas chromatography/mass espectrometry The arrangement mechanical of Photo-Fenton system has been shown big loss by volatilization of these compounds. The Fenton system has been shown capable of degradate benzene and toluene compounds, with massic percentage of remotion near the 99%. / A ind?stria de petr?leo e petroqu?mica em geral ? respons?vel por gerar uma grande quantidade de res?duos e efluentes qu?micos. Dentre alguns efluentes, ? poss?vel encontrar os compostos benzeno, tolueno, etilbenzeno e is?meros de xilenos, conhecidos como BTEX. Esses compostos s?o bastante vol?teis, t?xicos ao meio ambiente e potencialmente causadores de c?ncer no ser humano. Processos oxidativos avan?ados, POAs, s?o tecnologias n?o convencionais de tratamento de efluente, os quais podem ser aplicados no tratamento e remo??o desses compostos. Fenton ? um tipo de POA, o qual utiliza o reagente de Fenton, per?xido de hidrog?nio e sais de ferro, para promover a oxida??o de org?nicos. Enquanto que o tipo Foto-Fenton utiliza-se dos reagentes de Fenton acrescido de radia??o UV (ultra violeta). Esses dois tipos de POA, segundo a literatura, podem ser aplicados a sistemas compostos de BTEX. O presente trabalho consiste na avalia??o da utiliza??o das tecnologias Fenton e Foto-Fenton em solu??es aquosas de concentra??o de 100 ppm de BTEX, cada, simulando-se uma condi??o aproximada de efluente petroqu?mico. Foram utilizados reatores distintos para cada tipo de POA. Para as respostas anal?ticas de quantidade de remo??o foram utilizadas as t?cnicas SPME (solid phase microextraction) para extra??o em fase gasosa desses analitos e a cromatografia gasosa/espetrometria de massas. O arranjo mec?nico do sistema Foto-Fenton mostrou grandes perdas por volatiliza??o desses compostos. O sistema Fenton mostrou-se capaz de degradar os compostos benzeno e tolueno, com percentagens m?ssicas de remo??o na ordem de 99%.

Um estudo de caso e dois experimentos controlados de campo foram realizados, a fim de avaliar o impacto do etanol nos processos de atenuação natural que atuam em plumas de contaminação em fase dissolvida de gasolina. No estudo de caso, foi monitorada uma pluma de contaminação de E22 (gasolina com 22% de etanol em volume) em Itaguaí (RJ). Os dois experimentos controlados foram realizados no aqüífero de Borden, no Canadá, para estudar plumas de E10 e E95 (gasolinas com 10 e 95% de volume de etanol, respectivamente). Neste caso, foram realizadas injeções dos contaminantes abaixo do nível d\'água, gerando plumas que foram monitoradas. O etanol, em subsuperfície, particiona rapidamente para a água subterrânea, deixando a fase residual, e é transportado com a velocidade da água subterrânea. Os outros compostos orgânicos de gasolina migram com velocidades menores. Benzeno e tolueno apresentam velocidades mais próximas do etanol, enquanto trimetilbezenos e naftalenos são os mais retardados. Estas diferenças de migração dos compostos resultaram na separação espacial entre as plumas ao longo do período monitorado. A maior concentração de etanol detectada foi de 12.762 mg/L, que corresponde a um volume de etanol em água de 1,63%. As baixas concentrações de etanol não evidenciam que ele tenha exercido efeito cosolvente pronunciado na solubilidade dos compostos da gasolina. Os compostos orgânicos apresentaram perdas de massa ao longo do tempo de monitoramento. A biodegradação dos contaminantes foi observada pelo consumo de oxigênio dissolvido e metonogênese. O etanol apresentou a maior diminuição de massa e foi biotransformado mesmo sob condições anóxicas. O composto que apresentou a menos perda de massa foi o benzeno. A maior persistência de benzeno é atribuída à sua velocidade de migração próxima à água subterrânea associada ao efeito de consumo preferencial de receptores de elétrons pelo etanol. No estudo de caso, o desaparecimento de etanol pode estar relacionado à sua alta taxa de biodegradação, fato observado nos experimentos de campo. Entretanto, o efeito cosolvente na pluma, que explicaria o deplecionamento dos compostos mais móveis, como benzeno e tolueno, na pluma não foi comprovado nos experimentos. / A case study and two controlled field experiments were conducted to evaluate the impact of ethanol on the natural attenuation processes affecting dissolved phase of gasoline plumes. The case study was conducted in Itaguaí (RJ) where an E22 (gasoline with 22 % by volume of denatured ethanol) contaminant plume was studied. The controlled field experiments were conducted at the Borden aquifer in Canada to study plumes E10 and E95. In this case, contaminants were injected below the water table and plumes were monitored down gradient. In subsurface, ethanol partitions fastly from the residual phase and is transported with the ground water velocity. The other organic compounds migrate with lower velocities. Benzene and toluene present velocities close to ethanol, while trimethylbenzenes and naphthalene are the most retarded. These transport differences resulted in the spatial separation between the plumes throughout the monitoring period. The highest ethanol concentration detected was 12,762 mg/L, which corresponds to 1.63 % of ethanol volume in water. The ethanol concentrations detected do not support the cosolvency effect on the gasoline constituents of the plumes. The organic compounds presented mass losses throughout the monitoring period. Biodegradation was also demonstrated through dissolved oxygen consumption and methanogenesis. Ethanol presented the highest mass losses and was biotransformed under anoxic conditions. Benzene presented the smallest mass loss. Benzene´s higher persistence is related to the migration close to the ground water velocity and the preferential consumption of electron acceptors by ethanol. In the case study, the disappearance of ethanol can be related to its higher biodegradation rate, which was detected through the field experiments. However, the cosolvent effect in the plume, which would explain the depletion of the most mobile compounds such as benzene and toluene was not observed during the field experiments.