Diatoms are microscopic, photosynthetic, single-celled organisms that are useful in studies of water qualities (eg pH, nutrients, salinity). By analyzing changes in the species composition of diatoms back in time, gives an opportunity to interpret the marine environment affected by various factors (Andren et al, 1999). The aim of the study was to study changes in diatom abundance and composition in Hallsfjärden, a bay in the Baltic Sea located north of Himmerfjärden in Södertälje. The site was chosen because it is a bay that is assumed to have a large environmental impact due to external factors such as increased population growth, water treatment plants, industrial areas, dredging and a link to Lake Mälaren. The purpose of the study therefore to investigate whether there was an environmental impact in Hallsfjärden, in order to draw conclusions about what happened in the area and what has affected the water the last 100 years.      The survey is conducted by sampling sediment cores, studied by biostratigraphy of fossil diatoms to reconstruct past environmental conditions. The results of the analysis showed that oxygen deficiency was a particular problem, which is related to the eutrophication that are threatening some diatoms and thereby changes the species composition of ecosystems in Hallsfjärden. A plausible interpretation of the analyze results is that Hallsfjärden was adversely affected by the Södertalje area's population growth and Himmerfjärdsverkets startup by high emissions of nutrients. It has on the other hand appeared a positive impact for Himmerfjärdsverkets gradually improved purification with clearer water conditions. Hallsfjärden have proved to be a particularly sensitive ecosystem in this study, with low salinity and strong thermocline, which means that it is more affected by eutrophication and pollution in its drainage area. This causes a problem of eutrophication in Hallsfjärden due to the bay showing the influence of the surrounding areas and its emissions, which later exports further to the Baltic Sea via Himmerfjärden with the southbound flow. / Kiselalger är mikroskopiska, fotosyntetiserande, encelliga organismer som är användbara vid studier om vattenkvalitéer (till exempel pH, näringsämnen, salthalt). Genom att analysera förändringar i artsammansättningen av kiselalger bakåt i tiden kan tolkningar göras om hur havsmiljön påverkats av olika faktorer (Andrén m.fl., 1999). Målet med studien var att studera förändringar i kiselalgernas förekomst i Hallsfjärden, en havsvik i Östersjön belägen norr om Himmerfjärden i Södertälje. Platsen valdes för att det är en havsvik som antas ha stor miljöpåverkan på grund av yttre faktorer såsom en ökad befolkningstillväxt, reningsverk, industriområden, muddring och en kontakt med sjön Mälaren. Syftet med studien var därmed att undersöka om en miljöpåverkan fanns i fjärden, detta för att kunna dra slutsatser om vad som hänt samt vad som påverkat vattenområdet de senaste 100 åren.      Undersökningen är utförd genom provtagning av sedimentkärnor som undersökts avseende biostratigrafin av fossila kiselalger för att rekonstruera tidigare miljöförhållanden. Analysresultatet visade att syrebrist var ett utmärkande problem, vilket i samband med eutrofiering hotar vissa kiselalgsarter och förändrar därmed artsammansättningen i ekosystemen i Hallsfjärden. En sannolik tolkning av analysresultatet är att Hallsfjärden påverkats negativt av Södertäljeområdets befolkningstillväxt och Himmerfjärdsverkets uppstart genom höga utsläpp av näringsämnen. Det har å andra sidan synts en positiv inverkan efter Himmerfjärdsverkets successivt förbättrade rening med klarare vattenförhållanden. Hallsfjärden har i studien visat sig vara ett särskilt känsligt ekosystem med låg salthalt och starka språngskikt, vilket gör att det påverkas mer av eutrofiering och föroreningarna i området. Detta medför en övergödningsproblematik i Hallsfjärden, då fjärden visar en påverkan av omkringliggande områden och dess utsläpp av föroreningar, vilka även sedan exporteras ut i Östersjön via Himmerfjärden med den sydgående strömmen.

Made available in DSpace on 2016-08-10T10:53:48Z (GMT). No. of bitstreams: 1 QUEREN HAAMONAI SANTOS DA SILVA.pdf: 1839585 bytes, checksum: e87373a19afc13fac0e6123bdb351583 (MD5) Previous issue date: 2013-03-21 / This study analyzed the quality of the water consumed by the population of the 18 municipalities that make up the northern region of the state of Goiás, Brazil. Chemical analyzes were performed multielement (ICP-OES method) of the material collected in the Water Treatment Plants (WTP). From the results, we constructed a correlation matrix defining the geochemical associations. The analysis of integrated data revealed the presence of high concentrations (1 st, 2 nd and 3 rd order) of chemical elements and chemical compounds, respectively, Ba, Ca, Cl, Fe, Mg, Mn, Sr, Zn, SO4 and NO3. Visits were carried out in the cities studied ETAs, to check the type of water treatment, and evaluate possible environmental exposure. We stress the importance of this study as multielement disclosure about the quality of drinking water in the state of Goiás, emphasizing the multistakeholder nature of government agencies, civil society, in order to guide policy strategies to promote the quality of drinking water, as well as the preservation of water sources. / O presente trabalho analisou-se a qualidade da água consumida pela população dos 18 municípios que compõem a região norte do Estado de Goiás, Brasil. O objetivo atingido foi a classificação dos elementos químicos segundo a ordem de significância e o seu potencial de toxicidade. Pelas análises químicas multielementares (método ICP- OES) do material coletado nas Estações de Tratamento de Água (ETAs). A partir dos resultados, foi construída uma matriz de correlação definindo as associações geoquímicas. A analise integrada dos dados revelou a presença de altas concentrações (1º, 2º e 3º ordem) dos elementos químicos e compostos químicos, respectivamente, Ba, Ca, Cl, Fe, Mg, Mn, Sr, Zn, SO4 e NO3. Foram realizadas visitas nas ETAs dos municípios estudados, para verificação do tipo de tratamento da água, e avaliar uma possível exposição ambiental. Ressalta-se a importância deste estudo como divulgação sobre a qualidade multielementar da água potável, no Estado de Goiás, enfatizando o caráter multiparticipativo de órgãos governamentais, sociedade civil, de modo a orientar as estratégias políticas a fim de promover a qualidade da água potável, assim como a preservação dos mananciais.

Major studies conducted in Europe and North America has concluded that the current processes in wastewater treatment plants insufficiently degrade micropollutants e.g. pharmaceutical residues. Several sorption and oxidation methods has therefore been investigated with the purpose of removing or degrading micropollutants in wastewater. The main purpose of this project was, firstly, to validate the results from a pilot study conducted by Tekniska verken i Linköping AB (2014) which investigated the use of ozone to degrade pharmaceutical residues. Secondly, to investigate and design a suitable process control strategy for the ozonation process. Four different tests were conducted during the project, a dose-response test, step-response tests, a trace test, and a performance test. A poorer average reduction of pharmaceutical residues was observed in this project compared to the pilot study. An average reduction of approximately 80% was observed at the highest tested dose, 0.67 mg O3/mg DOC, N corr. Whilst an average reduction of 90% was observed at approximately 0.46 mg O3/mg DOC, N corr, in the pilot study. However, the quality of the wastewater was worse during this project compared to the pilot study. ΔUVA254 and offgas concentration of ozone were found to be suitable control parameters for process control. A control strategy based on a combination of these parameters was designed, where ΔUVA254 was used as the main control parameter and the off-gas concentration of ozone was used as a limiting controller to ensure a sufficient mass transfer in the system. In conclusion, a suitable flow proportional base ozone dose valid for current water conditions has been identified, 10 mg/L. Differences in wastewater quality which heavily influence the ozonation process have been identified. Lastly, a control strategy for process control of the ozonation have been identified, designed and is ready for implementation.

Os investimentos no setor de água potável no Brasil, apesar de significativos, ainda não apresentam os resultados esperados na melhoria da saúde e da qualidade de vida da população, especialmente nas pequenas comunidades do país. A aplicação de recursos continuará limitada enquanto não forem fortalecidos os aspectos técnicos, econômicos, institucionais, ambientais, sociais e culturais que permitam a seleção de obras sanitárias eficientes e sustentáveis. Neste contexto, foi desenvolvido um modelo conceitual de seleção de tecnologias de tratamento de água constituído por 17 sub-níveis que progressivamente \"filtram\" as opções tecnológicas aplicáveis em comunidades brasileiras inferiores a 20.000 habitantes. Os aspectos envolvidos no modelo se relacionam: i) ao risco presente na fonte de abastecimento superficial; ii) à eficiência das tecnologias para eliminar ou reduzir o risco a valores de acordo à Portaria no 518 (2004); iii) ao tratamento, aproveitamento e disposição dos resíduos gerados e iv) aos custos dos sistemas com vazões de projeto de 10 a 40 L/s. As principais conclusões da pesquisa foram: i) a aplicabilidade do modelo está restrita à estações de tratamento de água - ETAs que cumprem todos seus requisitos de domínio, ii) os valores-limite das variáveis de risco podem conduzir o engenheiro a uma seleção preliminar das possíveis alternativas de tratamento; entretanto, somente a partir de estudos de tratabilidade da água e de testes em instalação piloto será possível definir a ETA mais conveniente, iii) as seleções das tecnologias para tratamento, aproveitamento e disposição do resíduo não devem ser avaliadas de forma independente às empregadas nas ETA; iv) Os custos calculados pelo modelo dificilmente podem ser comparados com sistemas já existentes; v) os resultados do modelo variam em função dos dados de entrada; assim, o usuário deve ter consciência da qualidade da informação fornecida para obter resultados satisfatórios. / Despite being significant the investments in the brazilian drinking water sector still have not presented the expected results regarding the improvement of both health and population\'s life quality, especially in the small communities of the country. The application of resources will continue limited while the technical, economical, institutional, environmental, social and cultural aspects that allow for the selection of efficient and maintainable sanitary works are not strengthened. In this context, a conceptual model to select technologies for water treatment has been developed. It consists of 17 sub-levels that progressively \"filter\" the applicable technological options in brazilian communities of under 20.000 inhabitants. The aspects involved are related to: i) the risk present in the source of superficial supply; ii) the efficiency of the technologies to lither eliminate or reduce the risk to the values according law no 518 (2004); iii) the treatment, use and disposition of the generated residues and iv) the costs of the systems with project flows from 10 L/s to 40L/s. The main conclusions of the research were: i) the applicability of the model is restricted to water treatment plants - WTPs that accomplish all their domain requirements, ii) the limit values of the risk variables can lead the engineer to a preliminary selection of the possible treatment alternatives; however, only from studies of water treatment and tests in pilot installations it will be possible to define the most convenient WTP, iii) the selections of the technologies for treatment, use and disposition of residues should not be appraised in an independent way of the ones employed in WTPs, iv) the costs calculated by the model can hardly be compared with systems already existent; v) the results of the model vary in function of the input data; therefore, the user should be aware of the quality of the information supplied to obtain satisfactory results.

A unidade de estudo denominada bacia hidrográfica pode ser considerada um importante agente de integração entre processos naturais e antrópicos. Através do estudo do metabolismo dos corpos hídricos, pode-se conhecer fatores que implicam nas alterações funcionais destes processos. Seguindo nesse contexto, pode-se citar a bacia do rio Piracicaba, um autêntico modelo de bacia desenvolvida, com problemas ambientais típicos de áreas impactadas. Estudos desenvolvidos pelo Projeto PiraCena, entre os anos de 1994 e 2001, confirmaram que as emissões de esgotos domésticos e industriais e as mudanças no uso da terra, contribuíram para transformações drásticas no seu metabolismo. Entretanto, desde o encerramento deste projeto, recursos financeiros gerenciados pelos Comitês das Bacias Hidrográficas dos Rios Piracicaba, Capivari e Jundiaí foram aplicados, principalmente, em obras de saneamento como coleta e tratamento de esgotos domésticos. Assim, este estudo buscou avaliar durante doze meses a evolução de parâmetros físicos e químicos da água, visando conhecer como o processo de urbanização ainda afeta o metabolismo do rio e como os lançamentos de efluentes provenientes de estações de tratamento de esgoto interferem na composição química e no metabolismo aquático de ribeirões da bacia do rio Piracicaba, situados em regiões densamente ocupadas. Os resultados obtidos neste estudo foram ainda comparados com resultados publicados pelo Projeto PiraCena, com o objetivo de identificar possíveis melhorias na qualidade das águas desses ribeirões. Foi possível observar através dos resultados obtidos que apesar de todo esforço que tem sido feito visando a melhoria da qualidade da água dos corpos hídricos da bacia do rio Piracicaba, a deterioração ainda é continua. Além disso, foi possível reforçar os resultados encontrados pelo projeto PiraCena, uma vez que apesar de ter havido um aumento considerável no volume de esgoto doméstico tratado, esse tratamento não tem surtido efeito significativo sobre a qualidade da água de vários ribeirões da bacia. Portanto, é imperiosa uma avaliação detalhada sobre o funcionamento das estações de tratamento de esgoto para que as mesmas cumpram o seu papel que é prover a sociedade uma água de qualidade, assegurando ao mesmo tempo a integridade biótica da mesma. / The unit of study called watershed can be considered an important agent of integration between natural and anthropogenic processes. Studying the metabolism of water bodies, it is possible to know which factors are involved in the functional changes of these processes. In this context, it is inserted the Piracicaba river basin, an authentic model of developed basin with typical environmental issues of impacted areas. Studies conducted by PiraCena Project, between 1994 and 2001, confirmed that emissions from domestic and industrial sewage and changes in land use have contributed to drastic changes in its metabolism. However, since the end of the project, funds managed by the Watershed Committee of Piracicaba, Capivari and Jundiaí Watersheds were applied, mainly in sanitation, such as collection and treatment of domestic wastewater. Thus, this study aimed to evaluate the evolution of physical and chemical water parameters, during twelve months, trying to understand how the process of urbanization still affects the metabolism of the river and how the discharge of effluents from sewage treatment stations interfere in the chemical composition and the aquatic metabolism of streams that belong to the Piracicaba river basin, located in densely populated regions. The results obtained in this study were compared with previous results published by PiraCena Project, with the goal of identifying possible improvements at the water quality of these streams. It was observed from the results obtained that, despite every effort that has been made, aiming the improvement of the water quality at the water bodies of the Piracicaba river basin, the deterioration is still present. Moreover, it was possible to reinforce the results found by PiraCena project, since there was a considerable increase in the treated domestic sewage volume, but the effect of this treatment has not been significant to the quality of some streams of the basin. Therefore, the necessity of a detailed evaluation about the functioning of the sewage treatment stations is imperative, so they can continue providing the society with water of quality, while ensuring biotic integrity.

Les drogues illicites consommées sont éliminées sous forme inchangée ou métabolisée dans les urines et/ou les fèces et rejoignent le réseau d’égout. La quantification de ces produits d’élimination dans les eaux usées présente un double intérêt : d’une part, permettre d’évaluer la contamination des milieux naturels par ces composés et d’autre part, contribuer à l’estimation de la consommation de drogues illicites dans une population dépendant d’un même bassin collecteur des eaux usées urbaines. Des méthodes analytiques adaptées à la charge organique complexe des eaux usées ont été développées et validées pour évaluer les niveaux de contamination des affluents et effluents de 26 stations d’épuration en France pour dix-sept composés (drogues illicites et métabolites). Les résultats d’analyses ont permis d’évaluer les taux d’élimination de ces composés en fonction des technologies de traitement utilisées dans les stations d’épuration. Les concentrations mesurées dans les affluents ont été utilisées pour estimer les consommations de drogues illicites par un calcul en retour et ont montré des différences qualitatives et quantitatives de consommation de stupéfiants entre zones urbaines en France métropolitaine et en Outre-mer. Dans une dernière partie, des études de toxicologie sur un modèle bactérien et des études comportementales sur un modèle animal ont été conduites à des niveaux de concentrations proches des teneurs relevées en eau de surface et aucun effet notable n’a été observé. / Illicit drugs are metabolized or eliminated unchanged in the urine and/or feces then join the sewer system. The quantification of these products in wastewater disposal has two advantages: firstly, to assess the contamination of the environment and also contribute to the estimation of illicit drug consumption in a catchment. Analytical methods adapted to the complex organic load of wastewater have been developed and validated to assess the levels of contamination of influents and effluents from 26 sewage treatment plants in France for seventeen compounds (illicit drugs and metabolites). The results of the analysis were used to evaluate the elimination of these compounds depending on the treatment technologies used in wastewater treatment plants. Concentrations in the influent were used to estimate the illicit drug consumption by back calculation and showed qualitative and quantitative differences of drug use among urban areas in metropolitan France and overseas. In the last part, toxicology studies on a bacterial model and behavioural studies with an animal model have been conducted with concentration levels close to the levels found in surface water and no significant effect was observed.

Os esgotos sanitários concentram compostos que são interferentes endócrinos. Os tratamentos de esgotos convencionais por sistema de lodos ativados podem não remover totalmente estes compostos, os quais atingem os ecossistemas aquáticos e oferecem riscos ecológicos e à saúde humana. Neste trabalho, mediu-se a atividade estrogênica de compostos presentes em esgotos brutos, tratados e águas de reúso de duas estações de tratamento de esgotos (ETE) da região metropolitana de São Paulo, que operam por sistema de tratamento por lodos ativados e produzem águas de reúso para fins não potáveis por tratamento físico-químico. Nesse procedimento, as amostras foram preparadas por extração de fase sólida e utilizou-se o bioensaio BLYES (Bioluminescence Yeast Estrogen Screen) para a quantificação de efeito de atividade estrogênica em nanogramas de 17-estradiol equivalente (ng-EEQ/L). A estrogenicidade da amostra foi calculada por meio da EC50 (concentração efetiva em 50%), para isto foram utilizadas diluições seriadas para curva padrão com 17-estradiol e para cada amostra analisada. A toxicidade nos ensaios foi medida e monitorada pela levedura controle BLYR. A atividade estrogênica no esgoto bruto variou de 14,7 a 52,6 ng-EEQ/L Os resultados em esgotos tratados por sistema de lodos ativados variaram de abaixo o limite de quantificação do bioensaio de < 0,10 ng-EEQ/L a 11ng-EEQ/L, indicando eficiência de remoção entre 50% a 100%. As águas de reúso foram produzidas por filtração e cloração e na maioria dos resultados apresentaram atividade estrogênica de <0,10 ng-EEQ/L. Os resultados obtidos neste estudo foram comparáveis aos encontrados na literatura medidos pelo bioensaio YES. Os resultados demonstraram que o bioensaio BLYES foi viável para quantificar a estrogenicidade em todas as amostras testadas. As evidências acerca da atividade estrogênica das águas estudadas podem subsidiar ações integradas na gestão da qualidade das águas, o aprimoramento de condições operacionais e tecnológicas das ETEs / The wastewater concentrates compounds with endocrine disruptors. The conventional wastewater treatment by activated sludge are not able to completely remove these compounds, whose achieve aquatic ecosystems and offer ecologic risks and to human health. In this study we measured estrogenic activity on raw and treated wastewater and reclaimed water from two wastewater treatment plants (WWTPs) in the metropolitan region of São Paulo. These WWTPs treat wastewater by activated sludge process and produce reclaimed water for non potable purposes by physical chemical processes. By this procedure, the samples were collected on both WWTPs before and after described treatments and they were prepared by solid phase extraction (SPE). The samples after SPE were analyzed by the BLYES (Bioluminescence Yeast Estrogen Screen) bioassay for quantifying estrogenic activity measured by nanograms 17-estradiol equivalent per litre (ng-EEQ/L). The estrogenicity of sample was calculated by EC50 (half maximal effective concentration), for that were applied serial dilutions to 17-estradiol standard curve and for each sample. They were implemented serial dilutions for monitoring samples toxicity by BLYR yeast control. The estrogenic activity on raw wastewater ranged by 14,7 to 52,6 ng-EEQ/L. The treated wastewater by activated sludge presented results below the quantification of assay limit of < 0,10 ng-EEQ/L to 11ng-EEQ/L, indicating removal efficiency between 50% to 100%. The reclaimed water was produced by chlorination and filtration and presented results of estrogenic activity of < 0,10 ng-EEQ/L on majority analyzed samples. The results showed that BLYES bioassay was viable to quantify estrogenicity in all tested samples. The evidences on estrogenic activity in studied waters may offer subsidies for integrated actions on water quality management, improvements on operational conditions and technologies of WWTPs

Os esgotos sanitários concentram compostos que são interferentes endócrinos. Os tratamentos de esgotos convencionais por sistema de lodos ativados podem não remover totalmente estes compostos, os quais atingem os ecossistemas aquáticos e oferecem riscos ecológicos e à saúde humana. Neste trabalho, mediu-se a atividade estrogênica de compostos presentes em esgotos brutos, tratados e águas de reúso de duas estações de tratamento de esgotos (ETE) da região metropolitana de São Paulo, que operam por sistema de tratamento por lodos ativados e produzem águas de reúso para fins não potáveis por tratamento físico-químico. Nesse procedimento, as amostras foram preparadas por extração de fase sólida e utilizou-se o bioensaio BLYES (Bioluminescence Yeast Estrogen Screen) para a quantificação de efeito de atividade estrogênica em nanogramas de 17-estradiol equivalente (ng-EEQ/L). A estrogenicidade da amostra foi calculada por meio da EC50 (concentração efetiva em 50%), para isto foram utilizadas diluições seriadas para curva padrão com 17-estradiol e para cada amostra analisada. A toxicidade nos ensaios foi medida e monitorada pela levedura controle BLYR. A atividade estrogênica no esgoto bruto variou de 14,7 a 52,6 ng-EEQ/L Os resultados em esgotos tratados por sistema de lodos ativados variaram de abaixo o limite de quantificação do bioensaio de < 0,10 ng-EEQ/L a 11ng-EEQ/L, indicando eficiência de remoção entre 50% a 100%. As águas de reúso foram produzidas por filtração e cloração e na maioria dos resultados apresentaram atividade estrogênica de <0,10 ng-EEQ/L. Os resultados obtidos neste estudo foram comparáveis aos encontrados na literatura medidos pelo bioensaio YES. Os resultados demonstraram que o bioensaio BLYES foi viável para quantificar a estrogenicidade em todas as amostras testadas. As evidências acerca da atividade estrogênica das águas estudadas podem subsidiar ações integradas na gestão da qualidade das águas, o aprimoramento de condições operacionais e tecnológicas das ETEs / The wastewater concentrates compounds with endocrine disruptors. The conventional wastewater treatment by activated sludge are not able to completely remove these compounds, whose achieve aquatic ecosystems and offer ecologic risks and to human health. In this study we measured estrogenic activity on raw and treated wastewater and reclaimed water from two wastewater treatment plants (WWTPs) in the metropolitan region of São Paulo. These WWTPs treat wastewater by activated sludge process and produce reclaimed water for non potable purposes by physical chemical processes. By this procedure, the samples were collected on both WWTPs before and after described treatments and they were prepared by solid phase extraction (SPE). The samples after SPE were analyzed by the BLYES (Bioluminescence Yeast Estrogen Screen) bioassay for quantifying estrogenic activity measured by nanograms 17-estradiol equivalent per litre (ng-EEQ/L). The estrogenicity of sample was calculated by EC50 (half maximal effective concentration), for that were applied serial dilutions to 17-estradiol standard curve and for each sample. They were implemented serial dilutions for monitoring samples toxicity by BLYR yeast control. The estrogenic activity on raw wastewater ranged by 14,7 to 52,6 ng-EEQ/L. The treated wastewater by activated sludge presented results below the quantification of assay limit of < 0,10 ng-EEQ/L to 11ng-EEQ/L, indicating removal efficiency between 50% to 100%. The reclaimed water was produced by chlorination and filtration and presented results of estrogenic activity of < 0,10 ng-EEQ/L on majority analyzed samples. The results showed that BLYES bioassay was viable to quantify estrogenicity in all tested samples. The evidences on estrogenic activity in studied waters may offer subsidies for integrated actions on water quality management, improvements on operational conditions and technologies of WWTPs

Polychlorinated Biphenyls (PCBs) are persistent organic pollutants known for their toxicological effects. Though industrial production of legacy PCBs was banned in 1977, they can still be measured in nearly all environmental matrices. The Chicago Sanitary and Ship Canal (CSSC) is lined with industry and the receiving waters to the Stickney Water Reclamation Plant, the World's largest waste water treatment plant and was therefore speculated to be a potential source of PCBs to the Greater Chicago Area. Surficial sediment samples were acquired along a 45 km stretch of the CSSC, from Kedzie Ave. to Lockport. PCBs in the bulk sediment were extracted using accelerated solvent extraction while PCBs in the porewater were extracted using solid phase micro extraction. The PCBs were identified and quantified using a variation on EPA method 1668C. A total of 176 individual and coeluting PCBs were identified and quantified in this study. The sum of PCB concentrations in the bulk sediment was found to range from 70 to 4970 ng/g dry wt. The sum of PCB concentrations in the freely dissolved sediment-porewater was found to range from 2 to 366 ng/L. The bulk and porewater concentrations were used to estimate an average mass flow rate of PCBs through the CSSC of 368 kg/y. The large mass flow rate of PCBs passing through the CSSC and the fact that the CSSC connects Lake Michigan to the Mississippi River suggest that continued monitoring of PCB concentrations are necessary to better understand the transport and fate of PCBs in and out of the Great Chicago Area.

A large part of the antibiotics consumed ends up in wastewater, and in the wastewater the antibiotics may exert selective pressure for or maintain resistance among microorganisms. Antibiotic resistant bacteria and genes encoding antibiotic resistance are commonly detected in wastewater, often at higher rates and concentrations compared to surface water. Wastewater can also provide favourable conditions for the growth of a diverse bacterial community, which constitutes a basis for the selection and spread of antibiotic resistance. Therefore, wastewater treatment plants have been suggested to play a role in the dissemination and development of antibiotic resistant bacteria. Methicillin-resistant Staphylococcus aureus (MRSA) is a large problem worldwide as a nosocomial pathogen, but knowledge is limited about occurrence in non-clinical environments, such as wastewater, and what role wastewater plays in dissemination and development of MRSA.   In this thesis we investigated the occurrence of MRSA in a full-scale wastewater treatment plant (WWTP). We also investigated the concentration of genes encoding resistance to aminoglycosides (aac(6’)-Ie+aph(2’’)), β-lactam antibiotics (mecA) and tetracyclines (tetA and tetB) in three wastewater-associated environments: (1) soil from an overland flow area treating landfill leachates, (2) biofilm from a municipal wastewater treatment plant, and (3) sludge from a hospital wastewater pipeline. In addition, concentrations of mecA, tetA and tetB were investigated over the treatment process in the WWTP. These investigations were performed to determine how the prevalence and concentration of MRSA and the antibiotic resistence genes are affected in wastewater and wastewater treatment processes over time. The occurrence of MRSA was investigated by cultivation and a commercially available real-time PCR assay. In order to determine concentrations of the genes aac(6’)-Ie+aph(2’’), mecA, tetA and tetB in wastewater we developed a LUXTM real-time PCR assay for each gene.   Using cultivation and real-time PCR we could for the first time describe the occurrence of MRSA in wastewater and show that it had a stable occurrence over time in a WWTP. MRSA could mainly be detected in the early treatment steps in the WWTP, and the wastewater treatment process reduced the number and diversity of cultivated MRSA. However, our results also indicate that the treatment process selects for strains with more extensive resistance and possibly higher virulence. The isolated wastewater MRSA strains were shown to have a close genetic relationship to clinical isolates, and no specific wastewater lineages could be detected, indicating that they are a reflection of carriage in the community. Taken together, these data indicate that wastewater may be a potential reservoir for MRSA and that MRSA are more prevalent in wastewater than was previously thought.   The real-time PCR assays, for aac(6’)-Ie+aph(2’’), mecA, tetA, and tetB that we developed, were shown to be sensitive, fast, and reproducible methods for detection and quantification of these genes in wastewater environments. The highest concentrations of all genes were observed in the hospital pipeline, and the lowest in the overland flow system, with tetA and aac(6´)-Ie+aph(2´´) detected in all three environments. In the full-scale WWTP, we continuously detected mecA, tetA and tetB over the treatment process and over time. In addition, it was shown that the treatment process reduces concentrations of all three genes. The data presented in this thesis also indicate that the reduction for all three genes may be connected to the removal of biomass, and in the reduction of tetA and tetB, sedimentation and precipitation appear to play an important role.