É consenso entre os cientistas que as Estações de Tratamento de Esgoto são as principais formas de entrada de fármacos no ambiente aquático. Isso acontece porque os processos biológicos convencionais utilizados para o tratamento do esgoto sanitário não são eficientes quanto à remoção de muitos desses compostos sintéticos. Neste contexto, o pós-tratamento utilizando um Processo Oxidativo Avançado (POA) pode degradar os compostos pouco biodegradáveis e produzir água para reúso seguro. Portanto, esta Tese estuda o acoplamento entre um processo biológico anaeróbio-aeróbio e compara dois POA, foto-Fenton e Fenton heterogêneo, como alternativas de pós-tratamento. Os experimentos foram feitos utilizando-se esgoto sanitário real como matriz. Sendo assim, na primeira etapa deste trabalho, um método SPE-HPLC-MS/MS foi desenvolvido e validado para a quantificação dos fármacos Ranitidina, Diclofenaco e Sinvastatina naquela matriz complexa. Na segunda etapa, a degradação dos fármacos por processos biológicos foi estudada em reatores operados em batelada e de escoamento contínuo. Desenvolveu-se uma metodologia para a identificação dos produtos de biodegradação e encontrou-se que tais metabólitos são recalcitrantes e possuem potencial poluidor. Observou-se que os fármacos e seus metabólitos causam efeito tóxico crônico sobre a biomassa, pois a produção de metano foi prejudicada quando comparada à da biomassa que não foi exposta a esses compostos. Na terceira etapa, os POA foram estudados em batelada para se determinar as melhores condições de operação que seriam testadas nas etapas seguintes. Encontrou-se, para o processo foto-Fenton, que os fármacos foram completamente degradados quando se utilizavam duas lâmpadas (16 W de potência elétrica total), ferro (III) e peróxido de hidrogênio nas concentrações de 3,0 e 40 mg L−1, respectivamente, e tempo de detenção hidráulica de 10 min. Zeólita natural foi utilizada como suporte na síntese de um catalisador para Fenton heterogêneo. O catalisador foi estável em condições críticas de reação, porém não pôde degradar os compostos cujas dimensões moleculares eram maiores do que os seus poros. Os processos foram acoplados e operados em modo contínuo durante dez dias, período no qual permaneceram estáveis. Os custos foram estimados e verificou-se que, embora o processo Fenton heterogêneo necessite de 1/3 do capital comparado ao foto-Fenton, o processo heterogêneo não é interessante porque o custo operacional é 4 vezes maior e o processo é limitado para a degradação de moléculas pequenas. Já o processo foto-Fenton degradou todos os fármacos e metabólitos com remoção de carbono orgânico dissolvido e produzindo água potencialmente segura para seu reúso ao custo operacional de US$ 0,27 m−3. Portanto, o processo foto-Fenton foi a melhor alternativa de pós-tratamento avaliada nesta Tese. O processo Fenton heterogêneo seria atrativo apenas para a degradação de moléculas pequenas. / Scientists generally agree that Sewage Treatment Plants are the main inputs of pharmaceuticals into the aquatic environment. That happens because the conventional biological processes used for treating sewage are not efficient in removing many of those synthetic compounds. In this context, Advanced Oxidation Processes (AOP), used as post-treatments, can degrade the poorly biodegradable compounds and produce water for safe reuse. Therefore, this Thesis studies the coupling between an anaerobic-aerobic biological process and compares two AOP, photo-Fenton and heterogeneous Fenton, as post-treatment alternatives. The experiments were performed using real sewage as a matrix. Thus, in the first step of this work, an SPE-HPLC-MS/MS method was developed and validated for the quantification of the pharmaceuticals Ranitidine, Diclofenac, and Simvastatin in that complex matrix. In the second step, the pharmaceuticals degradation by biological processes was studied in batch and continuous flow reactors. A methodology was developed for identifying the biodegradation products and these metabolites were found to be recalcitrant and to have polluting potential. It was observed that the pharmaceuticals and their metabolites caused a chronic toxic effect on biomass, as methane production was impaired when compared to the biomass not exposed to these compounds. In the third step, the AOP were studied in batch mode to determine the best operating conditions that would be tested in the following steps. In the photo-Fenton process, the pharmaceuticals were completely degraded when two lamps (16 W total electric power), iron (III), and hydrogen peroxide were used in the concentrations of 3.0 and 40 mg L−1, respectively, with hydraulic detention time of 10 min. Natural zeolite was used as a support for the synthesized catalyst for heterogeneous Fenton. The catalyst was stable under critical reaction conditions, but it was not able to degrade compounds whose molecular dimensions were larger than its pores. The processes were coupled and operated in continuous mode for ten days, during which they remained stable. Considering the involved estimated costs, although the heterogeneous Fenton process requires 1/3 of the capital costs when compared to the photo-Fenton process, the heterogeneous one is not interesting because its operating cost is 4 times higher and it is limited to the degradation of small molecules. On the other hand, the photo-Fenton process degraded all pharmaceuticals and their metabolites, removed dissolved organic carbon, and produced water potentially safe for reuse at the operational cost of US$ 0.27 m−3. Therefore, the photo-Fenton process was the best post-treatment alternative assessed in this Thesis. The heterogeneous Fenton process would be suited only for the degradation of small molecules.

The global population is constantly rising and with the consequent increase in demand for clean water, the planet is facing a looming freshwater shortage. At the current rate, cities around the globe could lose as much as two thirds of their freshwater supply by 2050. To tackle this, there has been a huge surge on the investigation of novel wastewater treatment technologies. Advanced oxidation processes (AOPs) have shown great promise in this regard. Recently using microwaves with AOPs has been proven to exhibit improved reaction rates and thus there is a push towards developing processes involving microwaves and AOPs to achieve high water treatment efficiencies. However no methodical studies have been conducted to the best of our knowledge, to take the lab scale improvements successfully on to the pilot scale wastewater treatment system. To design such a system by coupling microwaves with Fenton process is the objective of this microwave assisted catalytic treatment of wastewater (MICROCAT) research project. Multiphysics simulation was used for cavity design optimisation and common pesticides found in agricultural wastewater were used as candidate impurities. A heterogeneous Fenton catalyst was prepared by a multi-stage thermal and chemical treatment of polyacrylonitrile (PAN) mesh on polypropylene support structure in collaboration with De Montfort University (DMU). The PAN meshes, after each stage of the treatment process, have been characterised using the field emission gun scanning electron microscope (FEGSEM) and electron dispersive X-ray spectroscopy (EDX) for microstructure and composition. The catalyst was used to study the decomposition of a model compound (e.g., carbetamide) using microwave radiation as well as conventional heating. Two kinds of trials were carried out constant power and constant temperature to observe the effect of variation of process parameters on the reaction rates. It was seen that the use of microwave heating enhanced the rate of decomposition compared to conventional heating in both scenarios. Attempts were also made to modify the composition of the catalyst and the support structure using polyvinylidene fluoride (PVDF) and carbon based additives (graphite and carbon black) to improve the microwave absorption characteristics. The combination of additive and PAN/PVDF mixtures has the potential to help in designing a suitable fabric support for catalyst that could be more receptive to microwaves, thereby helping to improve the energy efficiency of the process. Thorough investigation of dielectric properties and microwave absorption characteristics of the catalyst and support materials were performed independently. The heating rates of the meshes were monitored using an infrared thermal imaging camera. The absorption efficiencies of materials commonly used to build water treatment reactors such as polypropylene (PP), Fibreglass reinforced plastic (FRP), polyvinyl chloride (PVC), glass, PTFE, and fused quartz were assessed by subjecting them to constant microwave power experiments to ascertain their utility for making the reactor parts To take the successful lab scale results (100 ml) to scalable levels (80000 ml) for field trails, a new microwave reactor system was designed and tested. The cavity design was aided by multiphysics simulation of the electromagnetic field and temperature distribution inside the cavity. The model was created using COMSOL and provided valuable insight in making several design choices and improvements. The material data used in the model was determined both from our characterisation results and from corroborative literature data. The cavity itself was fully constructed using aluminium and the internal components were made using polypropylene and PTFE within the project timeline. The cavity was commissioned and initial testing at end user sites involved experiments measuring the rate of decomposition of carbetamide and other pesticides the results again emphasising that microwave treatment improves the reaction rates both from lab scale and in pilot scale water treatment situations in comparison to conventional treatment systems. This augers well for the generic applicability of the microwave assisted catalytic reactor system and its potential for the efficient treatment of contaminated water from hard to treat agricultural. Industrial, medical and defence waste/pollutants in future. An added advantage is that the developed microwave treatment system is mobile (on an ISO-container) and hence can reach the remote, contaminated site and treat it then and there rather than transporting the contaminated fluid to the treatment plant in a faraway location.

É consenso entre os cientistas que as Estações de Tratamento de Esgoto são as principais formas de entrada de fármacos no ambiente aquático. Isso acontece porque os processos biológicos convencionais utilizados para o tratamento do esgoto sanitário não são eficientes quanto à remoção de muitos desses compostos sintéticos. Neste contexto, o pós-tratamento utilizando um Processo Oxidativo Avançado (POA) pode degradar os compostos pouco biodegradáveis e produzir água para reúso seguro. Portanto, esta Tese estuda o acoplamento entre um processo biológico anaeróbio-aeróbio e compara dois POA, foto-Fenton e Fenton heterogêneo, como alternativas de pós-tratamento. Os experimentos foram feitos utilizando-se esgoto sanitário real como matriz. Sendo assim, na primeira etapa deste trabalho, um método SPE-HPLC-MS/MS foi desenvolvido e validado para a quantificação dos fármacos Ranitidina, Diclofenaco e Sinvastatina naquela matriz complexa. Na segunda etapa, a degradação dos fármacos por processos biológicos foi estudada em reatores operados em batelada e de escoamento contínuo. Desenvolveu-se uma metodologia para a identificação dos produtos de biodegradação e encontrou-se que tais metabólitos são recalcitrantes e possuem potencial poluidor. Observou-se que os fármacos e seus metabólitos causam efeito tóxico crônico sobre a biomassa, pois a produção de metano foi prejudicada quando comparada à da biomassa que não foi exposta a esses compostos. Na terceira etapa, os POA foram estudados em batelada para se determinar as melhores condições de operação que seriam testadas nas etapas seguintes. Encontrou-se, para o processo foto-Fenton, que os fármacos foram completamente degradados quando se utilizavam duas lâmpadas (16 W de potência elétrica total), ferro (III) e peróxido de hidrogênio nas concentrações de 3,0 e 40 mg L−1, respectivamente, e tempo de detenção hidráulica de 10 min. Zeólita natural foi utilizada como suporte na síntese de um catalisador para Fenton heterogêneo. O catalisador foi estável em condições críticas de reação, porém não pôde degradar os compostos cujas dimensões moleculares eram maiores do que os seus poros. Os processos foram acoplados e operados em modo contínuo durante dez dias, período no qual permaneceram estáveis. Os custos foram estimados e verificou-se que, embora o processo Fenton heterogêneo necessite de 1/3 do capital comparado ao foto-Fenton, o processo heterogêneo não é interessante porque o custo operacional é 4 vezes maior e o processo é limitado para a degradação de moléculas pequenas. Já o processo foto-Fenton degradou todos os fármacos e metabólitos com remoção de carbono orgânico dissolvido e produzindo água potencialmente segura para seu reúso ao custo operacional de US$ 0,27 m−3. Portanto, o processo foto-Fenton foi a melhor alternativa de pós-tratamento avaliada nesta Tese. O processo Fenton heterogêneo seria atrativo apenas para a degradação de moléculas pequenas. / Scientists generally agree that Sewage Treatment Plants are the main inputs of pharmaceuticals into the aquatic environment. That happens because the conventional biological processes used for treating sewage are not efficient in removing many of those synthetic compounds. In this context, Advanced Oxidation Processes (AOP), used as post-treatments, can degrade the poorly biodegradable compounds and produce water for safe reuse. Therefore, this Thesis studies the coupling between an anaerobic-aerobic biological process and compares two AOP, photo-Fenton and heterogeneous Fenton, as post-treatment alternatives. The experiments were performed using real sewage as a matrix. Thus, in the first step of this work, an SPE-HPLC-MS/MS method was developed and validated for the quantification of the pharmaceuticals Ranitidine, Diclofenac, and Simvastatin in that complex matrix. In the second step, the pharmaceuticals degradation by biological processes was studied in batch and continuous flow reactors. A methodology was developed for identifying the biodegradation products and these metabolites were found to be recalcitrant and to have polluting potential. It was observed that the pharmaceuticals and their metabolites caused a chronic toxic effect on biomass, as methane production was impaired when compared to the biomass not exposed to these compounds. In the third step, the AOP were studied in batch mode to determine the best operating conditions that would be tested in the following steps. In the photo-Fenton process, the pharmaceuticals were completely degraded when two lamps (16 W total electric power), iron (III), and hydrogen peroxide were used in the concentrations of 3.0 and 40 mg L−1, respectively, with hydraulic detention time of 10 min. Natural zeolite was used as a support for the synthesized catalyst for heterogeneous Fenton. The catalyst was stable under critical reaction conditions, but it was not able to degrade compounds whose molecular dimensions were larger than its pores. The processes were coupled and operated in continuous mode for ten days, during which they remained stable. Considering the involved estimated costs, although the heterogeneous Fenton process requires 1/3 of the capital costs when compared to the photo-Fenton process, the heterogeneous one is not interesting because its operating cost is 4 times higher and it is limited to the degradation of small molecules. On the other hand, the photo-Fenton process degraded all pharmaceuticals and their metabolites, removed dissolved organic carbon, and produced water potentially safe for reuse at the operational cost of US$ 0.27 m−3. Therefore, the photo-Fenton process was the best post-treatment alternative assessed in this Thesis. The heterogeneous Fenton process would be suited only for the degradation of small molecules.

Synthetic dyes are one of the highest pollutants of water resources, when disposed improperly they can cause a lot of damage to the aquatic ecosystems and the human health. Alternative processes to the degradation of such effluents, as Advanced Oxidation Processes (AOPs), are gaining more prominence. They are non-selective, do not produce residues and have a high rate of oxidation. Among the AOPs, the Fenton reaction is the most promising. However, there is still a great limitation for industrial application due to the small range of pH when the reaction occurs, and the large amount of sludge [Fe(OH)x] generated at the end of the process. To overcome these limitations, an alternative is the use of solid catalysts containing iron. This study proposes the development of composites based on RuO2, TiO2 and FeOx for use as catalysts in the Fenton reaction. The yellow sun dye was used as the pollutant model. The catalysts were deposited on a support of titanium by thermal decomposition. The catalysts were synthesized with ternary compositions (containing 10, 20, 40 and 60% of iron) and with binary compositions (containing 70% of iron), where materials were developed containing only Fe and Ru and containing only Fe and Ti. The efficiency and stability of these catalysts were evaluated, as well as the way how these materials are affected when there are changes during the synthesis process. The parameters analyzed were O2 injection during the calcination, increasing the calcination temperature and catalyst mass. The catalysts have been characterized by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The compositions containing 40, 60 and 70% of Fe were efficient in the oxidation of the chromophore group of the dye, with degradation rate of 80.13%, 90.03% and 75.41% (with Ru) and 60.39% (with Ti), respectively. The compositions with low proportions of Fe (10 and 20%) did not have good results, the decolorization rate was 3.53% and 27.81% respectively. The MEV analysis showed similar results for all the compositions, with mud-cracked surface as predominant surface. The EDX analysis data indicates uneven surfaces on the composition for all the studied catalysts. Some catalysts compositions showed efficiency, but the low stability of these materials promotes its phasing out. / Os corantes sintéticos são um dos maiores poluentes de recursos hídricos, quando despejados de forma inadequada causam uma série de danos aos ecossistemas aquáticos e à saúde humana. Métodos alternativos para a degradação desse tipo de efluente, como os processos oxidativos avançados (POA’s), vêm ganhando cada vez mais destaque. Estes são processos limpos, não seletivos e possuem alto poder de oxidação. Dentre os POA’s, a reação de Fenton é o mais promissor. No entanto, há ainda uma grande limitação para sua aplicação industrial devido à pequena faixa de pH para a reação e à grande quantidade de lama [Fe(OH)x] gerada ao final do processo. Para superar essas limitações, uma alternativa é o uso de catalisadores sólidos contendo ferro. O presente trabalho propôs desenvolver compósitos a base de RuO2, TiO2 e FeOx para serem utilizados como catalisadores da reação de Fenton. O corante amarelo sol foi o poluente modelo. Os catalisadores foram depositados em um suporte de titânio expandido mediante decomposição térmica. Foram sintetizados catalisadores com composições ternárias, contendo 10, 20, 40 e 60 % de ferro, e catalisadores com composições binárias, com 70% de ferro, onde foram desenvolvidos materiais contendo apenas Fe e Ru e materiais contendo apenas Fe e Ti. A eficiência e a estabilidade desses catalisadores foram avaliadas, e o modo como esses materiais são afetados quando alguns parâmetros durante o processo de síntese são alterados também foi investigado. A injeção de O2 durante o procedimento de calcinação, o aumento da temperatura de calcinação e o aumento da massa do catalisador foram os parâmetro estudados. Os catalisadores foram caracterizados por microscopia eletrônica de varredura (MEV) e por energia dispersiva de raios X (EDX). As composições contendo 40, 60 e 70% de Fe foram eficientes na oxidação do grupamento cromóforo do corante, apresentando 80,13%, 90,03% e 75,41% (com Ru) e 60,39% (com Ti) de degradação, respectivamente. Já as composições catalíticas com baixas proporções de ferro, 10 e 20%, não tiveram bons resultados, sendo a remoção de cor de apenas 3,53% e 27,81% respectivamente. As análises por MEV apresentaram resultados bem similares para todas as composições, onde a superfície prioritária foi a de barro-rachado. Os dados obtidos por EDX indicam superfícies não uniformes quanto à composição para todos os catalisadores estudados. Para os parâmetros avaliados, nenhum contribuiu de forma significativa no aumento da eficiência e da estabilidade dos catalisadores. Algumas composições catalíticas se mostraram eficientes, mas apresentaram baixa estabilidade, promovendo a gradual desativação dos catalisadores.