La contamination des milieux côtiers par des contaminants émergents est une préoccupation sociétale récente ce qui explique le peu de données disponibles, à ce jour dans ce milieu. Pourtant, certains de ces contaminants sont susceptibles de générer des effets écotoxiques sur les organismes aquatiques du milieu marin. Trois voies d’introduction de contaminants dans l’environnement marin sont communément identifiées : l’apport indirect depuis les bassins versants à travers les fleuves côtiers et les apports directs soit lors d’activités récréatives, soit par le rejet d’effluents d’eaux usées. Ce travail de thèse s’est focalisé sur les apports directs. L’objectif principal de cette thèse a été d’établir un état des lieux de la contamination du milieu marin par les pharmaceutiques et les produits de soin (PPCP) et d’évaluer leur apport par les activités récréatives et les eaux usées. Pour évaluer l’impact des activités de baignade sur la contamination marine, des analyses d’occurrence de filtres UV, substances principalement contenues dans les crèmes solaires ont été réalisées en zones côtières dans l’eau de mer et dans des organismes aquatiques, les moules. Les résultats de ces mesures ont montré des variations saisonnières et intra journalières de la concentration de filtres UV dans le milieu côtier, confirmant l’apport de ces substances par les activités récréatives. Le traitement par les stations d’épuration (STEP) ne permet pas une élimination complète de certains PPCP persistants. Pour évaluer l’impact des effluents de STEP sur les milieux récepteurs, des molécules pharmaceutiques et leurs formes conjuguées ont été recherchées dans des effluents domestiques et d’hôpitaux et en entrée et sortie de STEP. Les concentrations faibles de molécules conjuguées retrouvées en sortie de STEP ont démontré que les molécules conjuguées ne représentaient pas des marqueurs pertinents de la contamination marine par les eaux usées. Cependant les eaux usées traitées de manière partielle sont parfois rejetées directement dans le milieu marin via des émissaires en mer d’où l’importance de l’évaluation de cet apport. Les données acquises sur l’occurrence d’une molécule pharmaceutique, la venlafaxine et ses produits de transformation en sortie d’émissaire en mer a permis de confirmer la présence de ses molécules dans le milieu marin et l’importance d’inclure les métabolites dans les programmes de surveillance de la contamination marine. / Contamination of coastal environments by emerging contaminants is a recent societal concern, explaining the lack of data available today in this environment. However, some of these contaminants are likely to cause ecotoxic effects on aquatic organisms in the marine environment. Three ways of contaminants introduction into the marine environment are commonly identified: indirect inputs with catchments through coastal rivers and direct inputs through recreational activities and through the wastewater effluents. This work focused on direct contributions. The main objective of this thesis was to assess the current state of the contamination of the marine environment by pharmaceuticals and care products (PPCP) and to evaluate their contribution by the recreational activities and the wastewater releases. In order to assess the impact of bathing activities on marine contamination, occurrence studies of UV filters, substances mainly contained in sunscreens, have been carried out in coastal areas in seawater and in aquatic organisms and more precisely in mussels. The results showed seasonal and intra-day variations in the concentration of UV filters in the coastal environment, confirming that recreational activities contribute to introduce these substances in marine environment. Wastewater treatment plants (WWTP) does not allow the complete elimination of some persistent PPCPs. To evaluate the impact of WWTP effluents on the receiving environment, pharmaceuticals and their conjugated forms were analyzed in domestic and hospital effluents and in WWTP influents and effluents. The low concentrations of conjugated found in WWTP effluents demonstrated that the conjugated were not represented relevant markers of marine contamination by wastewater. However, partially treated wastewater is sometimes discharged directly into the marine environment via marine outfalls, hence the importance of assessing this input. The data on the occurrence of a pharmaceutical molecule, venlafaxine and its transformation products at marine outfall, confirmed the presence of its molecules in the marine environment and the importance of including metabolites in monitoring programs of marine contamination.

O presente trabalho tem por objetivo disponibilizar metodologia para o projeto de tratamento de esgoto sanitário através de disposição oceânica com utilização de emissário submarino, para localidades de pequeno porte. Também apresenta metodologia simplificada para obtenção de alguns dados oceanográficos necessários, na perspectiva de atender aos administradores dessas pequenas prefeituras envolvidas nas questões de atendimento de sua população quanto aos serviços de tratamento dos esgotos sanitários. Esses municípios, por serem pequenos e em país em desenvolvimento, carecem de recursos financeiros para as soluções convencionais de tratamento de esgotos sanitários. O trabalho contém uma revisão da bibliografia técnica relativa ao processo objeto deste estudo, não só referente ao projeto hidráulico como também à estabilidade física da tubulação do emissário assentada no leito do mar. Julgou-se necessário a realização, deste trabalho depois que se verificou que a implantação de emissários submarinos com diâmetros até da ordem de 300 mm, em geral tem seus custos inferiores aos dos sistemas convencionais. / This paper aims to provide a simplified methodology for the treatment design of sewage disposal through the use of oceanic outfall locations for small towns. It also features simplified methodology for obtaining oceanographic data needed for those small municipalities management. As these cities are usually on a development phase and have restricted resources to invest on its needs, the designed system becomes very attractive due to its low capital requirement. This work includes a technical review on the subject of this case study, not only regarding the water issues but also related to its physical stability of the outfall pipe at the bottom of the sea.It was felt necessary to organize this work after it was found that the introduction of submarine outfalls with diameters up to around 300 mm, has its costs below those of conventional systems. The most important result from this work is the competitiveness conclusion of the required implementation investment of submarine outfalls, with diameters up to 300 mm.

O presente trabalho tem por objetivo disponibilizar metodologia para o projeto de tratamento de esgoto sanitário através de disposição oceânica com utilização de emissário submarino, para localidades de pequeno porte. Também apresenta metodologia simplificada para obtenção de alguns dados oceanográficos necessários, na perspectiva de atender aos administradores dessas pequenas prefeituras envolvidas nas questões de atendimento de sua população quanto aos serviços de tratamento dos esgotos sanitários. Esses municípios, por serem pequenos e em país em desenvolvimento, carecem de recursos financeiros para as soluções convencionais de tratamento de esgotos sanitários. O trabalho contém uma revisão da bibliografia técnica relativa ao processo objeto deste estudo, não só referente ao projeto hidráulico como também à estabilidade física da tubulação do emissário assentada no leito do mar. Julgou-se necessário a realização, deste trabalho depois que se verificou que a implantação de emissários submarinos com diâmetros até da ordem de 300 mm, em geral tem seus custos inferiores aos dos sistemas convencionais. / This paper aims to provide a simplified methodology for the treatment design of sewage disposal through the use of oceanic outfall locations for small towns. It also features simplified methodology for obtaining oceanographic data needed for those small municipalities management. As these cities are usually on a development phase and have restricted resources to invest on its needs, the designed system becomes very attractive due to its low capital requirement. This work includes a technical review on the subject of this case study, not only regarding the water issues but also related to its physical stability of the outfall pipe at the bottom of the sea.It was felt necessary to organize this work after it was found that the introduction of submarine outfalls with diameters up to around 300 mm, has its costs below those of conventional systems. The most important result from this work is the competitiveness conclusion of the required implementation investment of submarine outfalls, with diameters up to 300 mm.

The City of Cape Town's (CoCT) wastewater management system discharges effluent from households, industries and other sources into the Atlantic Ocean through deep-water marine outfalls in Green Point, Camps Bay and Hout Bay. At total capacity, these three outfalls discharge 55.3 megalitres (Ml) into marine receiving environments daily. With minimal pre-treatment that amounts to screening and sieving, this results in microbial and chemical pollution of the sea (including chemicals of emerging concern), marine organisms, recreational beaches, and Marine Protected Areas (MPAs). This research focuses on contestations over evidence of that pollution in Hout Bay. The study documents the work of independent scientists seeking to provide evidence of coastal pollution obtained via microbial and chemical analyses of water (coastal and inland) and marine organisms (Mytilus galloprovincialis) samples. It also presents accounts of pollution obtained via ethnographic research with local residents, fishers, frequent water users and river activists who have observed and experienced poor coastal water quality. However, the form of evidence that is considered and informs decision-making processes by the CoCT has consistently sought to invalidate these forms of evidence, from both independent scientists and the public. Debates around knowledge of water and contests over evidence that highlight the entanglements of science, politics, and ways of knowing make visible a consistent pattern in coastal water-quality governance by the City, which results in inaction regarding the ever-growing issue of coastal pollution in Cape Town.