Neste trabalho, a partir da aplicação da teoria de controle ótimo, são estabelecidos sistemas de controle aplicáveis a três importantes sistemas aeróbios de tratamento de esgotos - filtros biológicos, processos de lodos ativados e os processos combinados formados a partir da combinação dos filtros biológicos e lodos ativados. Para a definição dos sistemas de controle são necessários modelos dinâmicos que descrevam o comportamento dos diferentes sistemas de tratamento. Da literatura são obtidos os modelos dinâmicos destinados à descrição do comportamento do processo de lodos ativados; para o filtro biológico, é proposto um modelo combinando à equação de balanço do reator e o modelo de ordem variável, este último destinado ao cálculo do fluxo de substrato para o interior de biofilmes profundos. Os resultados demonstram que, independentemente do sistema de tratamento considerado, os sistemas de controle reduzem substancialmente os tempos de acomodação e os desvios apresentados pelas variáveis de estado em relação as suas condições de equilíbrio. Por fim, função da inviabilidade de monitoramento de todas as variáveis de estado utilizadas para caracterizar os sistemas de tratamento, são propostos, a partir de modelos simplificados, controladores que incorporam a observação de estados. Também neste caso, os controladores estabelecidos permitem melhorar significativamente o desempenho dos sistemas de tratamento de esgotos analisados. / This paper constructs automatic control systems by means of optimal control theory for three different combinations of wastewater treatment units, namely, trickling filter, activated sludge process and a combined process. The dynamic model for the activated sludge process available in literature and a model proposed for the trickling filter were used in the construction of control systems. It is shown that the controls obtained in this study substantially reduce the durations necessary for the reestablishment of the equilibrium conditions in terms of state variables and the attenuation of oscillations around these conditions. Controls including observers for the state variables were devised on the basis of simplified models for the process in order to deal with the difficulties involved in monitoring all the state variables. These control systems were also found to be quite effective in improving the performance of the wastewater treatment plants considered in this paper.

Studies in Europe, Japan, and North America have reported that wild fish exposed to treated sewage effluents can exhibit significant physiological and reproductive abnormalities consistent with exposure to hormonally active chemicals. The main objective of this research project was to examine the estrogenic and androgenic activity in treated sewage to determine the risk associated with treated sewage discharges in Australia and New Zealand. Several bioassays, including a sheep estrogen receptor and a rainbow trout androgen receptor binding assay, were set up and validated with model compounds. The assays were then used to measure the estrogenic and androgenic activity in sewage samples from 15 municipal sewage treatment plants (STP) utilizing a variety of treatment technologies. Raw sewage samples contained high levels of both estrogenic and androgenic activity, up to 185 ng/L estradiol equivalents (EEq) and up to 9330 ng/L testosterone equivalents (TEq), respectively. Secondary treatment processes such as activated sludge had the greatest impact on removal of biological activity from the wastewater. The estrogenic and androgenic activity in final treated effluents were <1 to 4.2 ng/L EEq and <6.5 to 736 ng/L TEq, respectively. Based on lowest observable effective concentrations reported in the literature, these levels are unlikely to induce biological effects in exposed fish in the short term. To examine potential long-term effects, resident mosquitofish chronically exposed to undiluted treated sewage were sampled. Several morphological biomarkers indicative of endocrine disruption were measured and compared with mosquitofish captured at a reference site. Mosquitofish captured in a constructed wetland for tertiary treatment of secondary treated sewage exhibited morphological differences such as elongated anal fins consistent with exposure to androgenic chemicals, although this effect was not measurable in fish collected at sites further downstream or at any of the other sites. Based on these results, it is unlikely that mosquitofish populations would be significantly affected by exposure to final treated sewage. A reverse transcription real-time polymerase chain reaction (RT-PCR) method to measure the production of a female-specific protein (vitellogenin) mRNA in adult male mosquitofish was developed, and this could be used as a rapid test to detect early changes in individuals exposed to estrogenic activity.

Neste trabalho, a partir da aplicação da teoria de controle ótimo, são estabelecidos sistemas de controle aplicáveis a três importantes sistemas aeróbios de tratamento de esgotos - filtros biológicos, processos de lodos ativados e os processos combinados formados a partir da combinação dos filtros biológicos e lodos ativados. Para a definição dos sistemas de controle são necessários modelos dinâmicos que descrevam o comportamento dos diferentes sistemas de tratamento. Da literatura são obtidos os modelos dinâmicos destinados à descrição do comportamento do processo de lodos ativados; para o filtro biológico, é proposto um modelo combinando à equação de balanço do reator e o modelo de ordem variável, este último destinado ao cálculo do fluxo de substrato para o interior de biofilmes profundos. Os resultados demonstram que, independentemente do sistema de tratamento considerado, os sistemas de controle reduzem substancialmente os tempos de acomodação e os desvios apresentados pelas variáveis de estado em relação as suas condições de equilíbrio. Por fim, função da inviabilidade de monitoramento de todas as variáveis de estado utilizadas para caracterizar os sistemas de tratamento, são propostos, a partir de modelos simplificados, controladores que incorporam a observação de estados. Também neste caso, os controladores estabelecidos permitem melhorar significativamente o desempenho dos sistemas de tratamento de esgotos analisados. / This paper constructs automatic control systems by means of optimal control theory for three different combinations of wastewater treatment units, namely, trickling filter, activated sludge process and a combined process. The dynamic model for the activated sludge process available in literature and a model proposed for the trickling filter were used in the construction of control systems. It is shown that the controls obtained in this study substantially reduce the durations necessary for the reestablishment of the equilibrium conditions in terms of state variables and the attenuation of oscillations around these conditions. Controls including observers for the state variables were devised on the basis of simplified models for the process in order to deal with the difficulties involved in monitoring all the state variables. These control systems were also found to be quite effective in improving the performance of the wastewater treatment plants considered in this paper.

Norrvatten produces and delivers drinking water to approximately 700 000 people in the northern part of the Stockholm region in Sweden. In their water treatment plant Görvälnverket, water from Lake Mälaren is purified. During the purification, sludge is produced. To be able to use the sludge as landfilling material, it must be dewatered. Polyacrylamide is used as a flocculant for this purpose. However, in the reject water leaving the sludge and discharged into Lake Mälaren, acrylamide monomers are often left as a rest product from the manufacturing of polyacrylamide. The problem is that acrylamide is toxic to living organisms.  The aim of this master thesis was to evaluate proposed water treatment techniques to reduce acrylamide in the reject water leaving Görvälnverket and reach Norrvatten´s goal of an acrylamide concentration below 0.10 µg/l. The water treatment techniques evaluated were ozonation, moving bed biofilm reactor and trickling filter. Along with that, oxidative stress and genotoxicity from the ozone were analysed. Also, the ability of Lake Mälaren to degrade acrylamide was evaluated. The ozone tests were performed in a pilot plant in a laboratory at IVL Swedish Environmental Research Institute (IVL Svenska Miljöinstitutet), the moving bed biofilm reactor- and the trickling filter test were performed in pilot plants at Görvälnverket and the degradation tests in water from Lake Mälaren were performed at Görvälnverket as well.  The results showed that ozonation of the reject water could reduce acrylamide in the reject water and fulfil Norrvatten´s goal of below 0.10 µg/l acrylamide. When an ozone dose of 0.70 mg/l was applied to the reject water with an acrylamide concentration of 2.5 µg/l, more than 98 % of the acrylamide was reduced. Furthermore, no oxidative stress or genotoxicity seemed to be generated from the ozonation. The moving bed biofilm reactor and the trickling filter did reduce the acrylamide by 80.77 % and 94.7 % respectively and the results suggested that they could be used to reach Norrvatten´s goal. Finally, the results indicated that water from Lake Mälaren could degrade acrylamide at a temperature of 15 °C in 4 days and in 8 °C in 13 days and reach the goal. / Norrvatten producerar och levererar dricksvatten till cirka 700 000 människor i norra delen av Region Stockholm i Sverige. I deras vattenverk Görvälnverket renas vatten från Mälaren. När sjövattnet renas produceras slam. För att slammet ska kunna användas som landfyllnadsmaterial måste det avvattnas. Polyakrylamid används som flockningsmedel i det syftet. I rejektvattnet som lämnar slammet och släpps ut i Mälaren finns ofta akrylamid monomerer kvar som en restprodukt från framställning av polyakrylamid. Problemet med detta är att akrylamid är toxiskt för levande organismer.  Syftet med detta masterexamensarbete var att evaluera föreslagna vattenreningstekniker för att reducera akrylamid i rejektvattnet som lämnar Görvälnverket och inte överstiga en akrylamidkoncentration på 0,10 µg/l som är Norrvattens mål. Vattenreningsteknikerna som evaluerades var ozonering, biofilmreaktor med rörlig bädd och biobädd. Utöver det var oxidativ stress samt genotoxicitet från ozoneringen analyserad. Dessutom var nedbrytningsförmågan av akrylamid i Mälaren testad. Ozonerings försöken utfördes i en pilotanläggning i ett laboratorium hos IVL Svenska Miljöinstitutet, testerna med biofilmreaktor med rörlig bädd och biofilter utfördes i pilotanläggningar på Görvälnverket och nedbrytningstesterna i Mälarvatten utfördes också på Görvälnverket.  Resultaten visade på att ozonering av rejektvattnet kan reducera akrylamid och uppfylla Norrvattens mål om en akrylamidkoncentration på mindre än 0,10  µg/l. När en ozondos på 0,70 mg/l applicerades i rejektvattnet med en akrylamidkoncentration på 2,5 µg/l reducerades mer än 98 % av akrylamiden. Vidare tycktes inte ozoneringen bidra till oxidativ stress eller genotoxicitet. Biofilmreaktorn med rörlig bädd och biofiltret reducerade akrylamid med 80,77 % respektive 94,7 %.  Resultaten visade att dessa tekniker skulle kunna användas för att nå Norrvattens mål. Utöver detta visade studien att vatten från Mälaren kan bryta ner akrylamid i 15 °C på 4 dagar och i 8 °C på 13 dagar och nå målet.

L'objectif principal de ce travail de thèse concerne l'étude de l' élimination de la DCO et de la nitrification dans une nouveau lit bactérien Multi-Section ( MSB ) . Après une caractérisation de l’hydrodynamique et du transfert d’oxygène de ce lit bactérien, les expériences biologiques menées sous des conditions opératoires contrastées (fortes et faibles charges organiques eteaux usées contenant ou pas des matières particulairs) ont été menées. En parallèle, des simulations avec le logiciel Biowin® ont été réalisées. Les principaux résultats sont résumés en suivant :- La rétention de liquide statique est majoritaire par rapport à la rétention dynamique que ce soit en présence ou en absence de biofilm. Le biofilm joue le rôle d’une "éponge" permettant un maintien de l’humidité du lit même à faible débit. Les expériences de DTS ont montré que le biofilm accroit le temps de séjour du liquide et conduit à une diminution de l’épaisseur du film liquide permettant ainsi de promouvoir le transfert de l'oxygène.- Le réacteur MSB montre une élimination efficace de la DCO (> 95 % ) et de la nitrification ( > 60 % de l’azote entrant), mais une accumulation de DCO particulaire a lieu dans le filtre ce qui conduira à un colmatage à terme. La nitrification cohabite avecl’élimination de la DCO même dans la première section et pour une charge organique élevée ce qui implique une bonne capacité d’oxygénation du MSB par l’aération naturelle.- Un modèle dynamique de MSB a été utilisé implémenté sur le simulateur - BioWin , afin d'obtenir la répartition des biomasses au sein du réacteur et d'évaluer le processus limitant dans chaque section. Le modèle partiellement calibré peut aider à estimer les besoins minimum d'oxygène pour la nitrification et peut rendre compte de la compétition entre la croissance hétérotrophe et la nitrification. / The main objective of this PhD work focused on the study of the COD removal and nitrification in a new designed Multi-Section Bioreactor (MSB). Hydrodynamic characterization of the reactor, biological experiments under contrasted conditions and simulations by Biowin® software were carried out:- Firstly, it was found that static liquid retention is the predominant part both without and with the presence of biofilm. Biofilm acts like a "sponge". RTD experiments showed that biofilm can promote liquid residence time, decrease the liquid film andpromote the oxygen transfer consequently.- Secondly, the MSB operated at contrasted organic loading rate (OLRs) and nitrogen loading rate (NLRs) showed that COD can be effectively removed (removal efficiency > 95%) and nitrification (> 60% of the N removal) occurred in this biofilter.Nitrification is efficient even in the first section implying no drastic oxygen limitation though only natural aeration is occurring.- Thirdly, a TF dynamic model has been used from a simulator - BioWin, in order to get more insights on the biomass distribution in the pilot and to assess the limiting process in each section of the bioreactor. Calibration of the model can help us to estimate theminimum oxygen requirement for nitrification for each zone inside the pilot and it can well represent the competition between heterotrophic growth and nitrification.