During ferrochrome (FeCr) production, three types of generic chromium (Cr) containing wastes are generated, i.e. slag, bag filter dust (BFD) and venturi sludge. The loss of these Cr units contributes significantly to the loss in revenue for FeCr producers. In this study, the liberation of Cr units was investigated utilising two case study waste materials, i.e. BFD from a semi-closed submerged arc furnace (SAF) operating on acid slag and the ultrafine fraction of slag (UFS) originating from a smelter operating with both open and closed SAFs on acid slag. A detailed material characterisation was conducted for both case study materials, which included particle size distribution, chemical composition, chemical surface composition and crystalline content. Cr liberation was achieved utilising two methods, i.e. aqueous ozonation and the advanced oxidation method. Various advanced oxidation processes could be applied. However, the advanced oxidation processes considered in this study was the use of gaseous ozone (O3) in combination with hydrogen peroxide (H2O2). Controlling parameters such as the influence of pH, ozonation contact time, waste material solid loading, gaseous O3 concentration and temperature on Cr liberation were investigated for the aqueous ozonation process. The influence of pH, volume H2O2 added and the method of H2O2 addition were considered for the advanced oxidation process. Results indicated that with aqueous ozonation, limited Cr liberation could be achieved. The maximum Cr liberation achieved was only 4.2% for BFD by varying the process controlling parameters. The Cr liberation for UFS was significantly lower than that of the BFD. The difference in the results for the two waste materials was attributed to the difference in characteristics of the materials. The Cr content in BFD was mostly related to chromite and/or altered chromite particles, while the Cr content of the UFS was mostly related to FeCr particles. It is possible that the Cr(III) present in the chromite and/or partially altered chromite might be more susceptible to oxidation to Cr(VI) than the metallic Cr(0) present in the FeCr. During ozonation, aqueous O3 spontaneously decomposes to form hydroxyl (OH•) radicals, which are very strong oxidants in water. The above-mentioned Cr liberation observed was related to the formation of the OH• radicals during the spontaneous decomposition of aqueous O3. This was indicated especially by enhanced Cr liberation at higher pH values, which was attributed to the acceleration of the spontaneous decomposition to OH• radicals at higher pH levels. The advanced oxidation method gave significantly higher Cr liberation results for both case study materials considered, achieving Cr liberations of more than 21%. The advance oxidation processes improve normal oxidation methods. In this study, the H2O2 used in combination with O3 enhanced the formation of the OH• radicals that are responsible for the oxidation of Cr. The Cr liberation levels achieved are possibly not high enough to be feasible for industrial purposes. However, a further investigation of the advanced oxidation process could optimise the process to yield even higher Cr liberation. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

During ferrochrome (FeCr) production, three types of generic chromium (Cr) containing wastes are generated, i.e. slag, bag filter dust (BFD) and venturi sludge. The loss of these Cr units contributes significantly to the loss in revenue for FeCr producers. In this study, the liberation of Cr units was investigated utilising two case study waste materials, i.e. BFD from a semi-closed submerged arc furnace (SAF) operating on acid slag and the ultrafine fraction of slag (UFS) originating from a smelter operating with both open and closed SAFs on acid slag. A detailed material characterisation was conducted for both case study materials, which included particle size distribution, chemical composition, chemical surface composition and crystalline content. Cr liberation was achieved utilising two methods, i.e. aqueous ozonation and the advanced oxidation method. Various advanced oxidation processes could be applied. However, the advanced oxidation processes considered in this study was the use of gaseous ozone (O3) in combination with hydrogen peroxide (H2O2). Controlling parameters such as the influence of pH, ozonation contact time, waste material solid loading, gaseous O3 concentration and temperature on Cr liberation were investigated for the aqueous ozonation process. The influence of pH, volume H2O2 added and the method of H2O2 addition were considered for the advanced oxidation process. Results indicated that with aqueous ozonation, limited Cr liberation could be achieved. The maximum Cr liberation achieved was only 4.2% for BFD by varying the process controlling parameters. The Cr liberation for UFS was significantly lower than that of the BFD. The difference in the results for the two waste materials was attributed to the difference in characteristics of the materials. The Cr content in BFD was mostly related to chromite and/or altered chromite particles, while the Cr content of the UFS was mostly related to FeCr particles. It is possible that the Cr(III) present in the chromite and/or partially altered chromite might be more susceptible to oxidation to Cr(VI) than the metallic Cr(0) present in the FeCr. During ozonation, aqueous O3 spontaneously decomposes to form hydroxyl (OH•) radicals, which are very strong oxidants in water. The above-mentioned Cr liberation observed was related to the formation of the OH• radicals during the spontaneous decomposition of aqueous O3. This was indicated especially by enhanced Cr liberation at higher pH values, which was attributed to the acceleration of the spontaneous decomposition to OH• radicals at higher pH levels. The advanced oxidation method gave significantly higher Cr liberation results for both case study materials considered, achieving Cr liberations of more than 21%. The advance oxidation processes improve normal oxidation methods. In this study, the H2O2 used in combination with O3 enhanced the formation of the OH• radicals that are responsible for the oxidation of Cr. The Cr liberation levels achieved are possibly not high enough to be feasible for industrial purposes. However, a further investigation of the advanced oxidation process could optimise the process to yield even higher Cr liberation. / MSc (Chemistry), North-West University, Potchefstroom Campus, 2014

This research involved an investigation of the application and reaction mechanisms of UV/H₂O₂ for the simultaneous removal of regulated halogenated disinfection byproducts (DBPs) and odorous aldehydic algal byproducts in the presence of geosmin and 2-methylisoborneol, which are earthy-musty odorants that commonly occur in drinking water. UV/H₂O₂ is an expensive advanced oxidation process that is used to successfully control geosmin and 2-methylisoborneol. The aqueous oxidation of odorous aldehydes and halogenated DPBs were compared to that of the earthy-musty odorants and the changes to the sensory properties of the drinking water were examined. Geosmin, 2-methylisoborneol, heptadienal, decadienal, and nonadienal, hexanal, and the two most prevalent classes of DBPs, trihalomethanes (THMs) and haloacetic acids (HAAs) were oxidized by UV photolysis alone and the UV/H₂O₂ process with 6 mg/L H₂O₂ and realistic ng/l to μg/L concentrations of the test compounds. The di-, and tri-brominated THMs and HAAs were substantially (80-99%) removed by direct UV photolysis mechanism at the same UV/H₂O₂ dose required for removing 95% of geosmin and 65% of 2-methylisoborneol with faster reaction rates for the more bromine substituted compounds. The C-Br bond cleavage is the first step of brominated HAAs degradation by UV photolysis, and followed by either of two second steps: reaction with oxygen producing peroxyl radical or interaction with water molecule causing O-H insertion/H-Br elimination. Trichloromethane and mono-, di-, and tri-chlorinated HAAs were not substantially removed under the same conditions used for the brominated compounds. The principal removal mechanism was by the reaction with hydroxyl radical for the UV/H₂O₂ process. The second order reaction rate constants were on the order of 10⁶ - 10⁸ M⁻¹ s⁻¹ with faster reaction rates for the less chlorine substituted compounds. Based on the reaction rates, hydrogen and halogen ion balance, and isotope effect, both hydrogen abstraction and electron transfer reaction were involved in the first steps of the chlorinated HAA degradation. Three odorous aldehydes - heptadienal, decadienal, and nonadienal - were removed faster than geosmin or 2-methylisoborneol, and direct UV photolysis was the principal reaction mechanism for the removal of these unsaturated aldehydes. Hexanal was poorly removed. In sensory tests, new odors such as sweet or chalky odors were produced while the concentration and initial odor intensity of these fishy/grassy-smelling aldehydes were reduced with increasing exposure time to UV/H₂O₂. Carbonyl compounds were detected as products of the UV photolysis of nonadienal. These carbonyls were not removed by further UV irradiation, which was thought to be partially related with production of new odors. The results indicate that the UV/H₂O₂ is effective to control both odorous compounds and brominated DBPs. This process can be seasonally applied to control both contaminants especially, in the warm summer when both odorants and DBPs have their higher concentrations. Removal of brominated DBPs can be a significant addition to water utilities that have difficulty in meeting regulatory levels for these highly toxic compounds. The result on the removal of odorous aldehydes indicate that new types of odors were produced from the oxidation of odorous aldehydes suggesting sensory test coupled with chemical analysis should be considered in designing oxidation process to control recalcitrant odorants. / Ph. D.

No processo UV/H2O2, oxidar o substrato a CO2 e água resulta em um elevado consumo de H2O2. Então, esse processo tem sido proposto como um pré-tratamento para reduzir a toxicidade a níveis seguros para o tratamento biológico posterior. Por essa razão, é necessário estudar o progresso da reação, pois a toxicidade de alguns intermediários formados durante a oxidação pode ser mais elevada que a do composto inicial. Neste trabalho, os experimentos foram realizados em um reator tubular fotoquímico, contendo em seu eixo uma lâmpada de vapor de mercúrio de baixa pressão, conectado a um tanque de recirculação. O processo UV/H 2O2 é aplicado no tratamento de água contendo fenol (50500mg C.L-1). Os resultados demonstraram que o principal produto da oxidação primária é o catecol, indicando que a hidroxilação ocorre predominantemente na posição orto. A abertura do anel aromático leva à formação de ácidos orgânicos, o que explica a diminuição do pH durante a reação. Foram identificados os seguintes ácidos: fórmico, oxálico, maleico e malônico. Na etapa seguinte desse trabalho, dois modelos cinéticos foram desenvolvidos. Os modelos foram baseados nas reações químicas e fotoquímicas iniciadas pelos radicais hidroxila gerados pela fotólise do peróxido de hidrogênio. Foram utilizados os valores encontrados na literatura para os parâmetros fotoquímicos e constantes cinéticas das reações fotoquímicas. Os resultados experimentais foram utilizados para estimar as constantes cinéticas das reações que envolvem os compostos aromáticos. No primeiro modelo foram contempladas todas as reações fotoquímicas envolvidas e, no segundo, apenas as consideradas mais significantes. Os resultados das simulações considerando os parâmetros ajustados mostraram uma melhor concordância com os dados experimentais para o primeiro modelo. As constantes cinéticas deste modelo para as reações nas quais o fenol é oxidado a catecol (k14) e hidroquinona (k15) foram 2,60x108L.mol-1.s-1 e 1,03x108L.mol-1.s-1, respectivamente. As constantes cinéticas para a oxidação do catecol (k17) e hidroquinona (k18) encontradas foram 1,41x108L.mol-1.s-1 e 2,02x108L.mol-1.s-1, respectivamente. Também foi observada elevada correlação entre as constantes k14 e k17 e entre k15 e k18. / In the UV/H2O2 process, the oxidation of the substrate to CO2 and water results in high H2O2 consumption. Due to this fact the process has been proposed as a pretreatment to reduce toxicity to safe levels prior to biological treatment. Thus, it is necessary to study the reaction progress because some intermediate compounds may be more toxic than the initial compound. In the present study experiments were carried out in a lab-scale tubular photochemical reactor with a low-pressure mercury vapor lamp placed in its axis, connected to a recirculation tank. The UV/H2O2 process was applied to the degradation of an aqueous solution containing phenol as a model pollutant (concentration range: 50-500mg.L-1). The experimental results indicated that orto-hydroxylation (catechol formation) was predominant. The cleavage of the aromatic ring resulted in the production of organic acids, which caused the pH decrease over the reaction time. The following acids were detected: formic, oxalic, maleic and malonic. The experimental results were used to estimate kinetic rate constants for the reactions involving aromatic compounds according to two kinetic models based on chemical and photochemical reactions, initiated by hydrogen peroxide photolysis to produce hydroxyl radical. Numerical values of chemical reaction rate constants and photochemical parameters were taken from literature. The first model considered all photochemical while the second model considered the most significant ones. The parameter fitting results showed better agreement with experimental values based on the first model. The resulting values for the rate constants according to this model were as follows: 2.60x108L.mol-1.s-1 for phenol oxidation to catechol, and 1.03x108L.mol-1.s-1 for phenol oxidation to hydroquinone by hydrogen peroxide. The reaction rate constants for the oxidation of catechol, and hydroquinone by hydrogen peroxide are 1.41x108L.mol-1.s-1 and 2.01x108L.mol-1.s-1, respectively. A high correlation was observed between constants k14 and k17, and between k15 and k18.

O efluente fenólico em estudo apresenta a relação DBO5/DQO (Demanda Bioquímica de Oxigênio/ Demanda Química de Oxigênio) igual a 0,15, ou seja caracteriza-se por ser um efluente não biodegradável. No tratamento inicial do efluente utilizou-se ozônio, na presença do sal de ferro II proveniente da solução de sulfato ferroso heptaidratado 0,82 mol. L-1 e do peróxido de hidrogênio , que possui a finalidade catalítica na formação dos radicais hidroxilas, com alto poder de oxidação da matéria orgânica. Nesta etapa foi estudado a união dos processos oxidativos O3/UV e Foto-Fenton, Foram tratados 3 L do efluente fenólico in natura em um reator fotocatalítico com lâmpada ultravioleta. Em todos os experimentos o pH e a temperatura do meio reacional foram controlados. Os experimentos foram executados segundo um planejamento de Taguchi L16, no qual a variável entrada de maior importância para a degradação da matéria orgânica foi o peróxido de hidrogênio. As variáveis respostas analisadas foram a concentração do Carbono Orgânico Total, Demanda Química de Oxigênio e Fenóis Totais. No planejamento de Taguchi L16 foram selecionadas as variáveis significativas para o processo de degradação do efluente fenólico, a fim de serem otimizadas através do Método de Superfície de Resposta (MSR Foto-Fenton e O3/UV). O método de otimização MSR Foto-Fenton foi eficiente na degradação do composto fenólico, sendo assim a melhor condição experimental da planilha de otimização foi a de número 10 e corresponde a uma redução de COT= 54,68%, DQO=78,73% e Fenois Totais= 98,1%. Os parâmetros controlados do processo para essa condição foram: pH=3, temperatura de 30 ºC, potência ultravioleta de 28 W e reagente Fenton (H2O2= 48,3g e Fe+2 =5,95g), que corresponde a relação mássica H2O2 /Fe+2 igual a 8. / The phenolic effluent in this study has the rate DBO5/DQO (Biochemical Oxygen Demand / Biochemical Oxygen Demand) equal to 0.15, which is characterized by an effluent to be non-biodegradable. In the initial treatment of phenol was used ozone in the presence of iron salt II from the solution of ferrous sulfate heptahydrate 0.82 mol. L-1 and hydrogen peroxide, which has the purpose in the catalytic formation of hydroxyl radicals with high oxidation power of organic matter. In this stage, was studied the union of the oxidative process O3/UV and Photo-Fenton. The effluent was treated about 3 L about in a photocatalytic reactor with UV lamp. In all experiments, the pH and temperature of the reaction medium were control. The experiments are being carried out to a Taguchi L16 design, in which the input variable of greatest importance to the degradation of organic matter was hydrogen peroxide. The response variable analyzed was given by the concentration of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) and Total Phenols (FT). In planning Taguchi L16 significant variables were selected for the degradation process of phenolic wastewater in with purpose of to be optimized by Response Surface Method (RSM Photo-Fenton and O3/UV). The optimization method was efficient photo-Fenton degradation of phenolic compound, so the best experimental condition spreadsheet optimization was the number 10 and corresponds to a reduction of TOC = 54.68%, COD = 78,73% and Total Phenols= 98.1%. The controlled process parameters for this condition were: pH = 3, temperature of 30 ° C, power of 28 W ultraviolet and Fenton reagent (H2O2= 48,3g and Fe+2 = 5,95g), corresponding to mass ratio H2O2 / Fe +2 = 8.

Submitted by JOSIANE SANTOS DE OLIVEIRA (josianeso) on 2017-05-25T11:43:55Z No. of bitstreams: 1 Alisson Schons_.pdf: 2733792 bytes, checksum: 704c4ce2631dfdbe7af1fc3c3e324404 (MD5) / Made available in DSpace on 2017-05-25T11:43:56Z (GMT). No. of bitstreams: 1 Alisson Schons_.pdf: 2733792 bytes, checksum: 704c4ce2631dfdbe7af1fc3c3e324404 (MD5) Previous issue date: 2016-02-24 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / UNISINOS - Universidade do Vale do Rio dos Sinos / O lixiviado de aterro sanitário tem se caracterizado pela alta concentração de matéria orgânica recalcitrante, nitrogênio amoniacal e compostos tóxicos. Compostos orgânicos recalcitrantes são raramente removidos por processos tradicionais de tratamentos de efluentes, o que dificulta o atendimento aos padrões de lançamento de efluentes. Da mesma forma, o descarte do esgoto doméstico gerado pelas comunidades precisa também de tratamentos prévios para não impactar o meio ambiente. Devido às características do esgoto doméstico, com baixas concentrações de matéria orgânica carbonácea e cor em relação ao lixiviado, vem permitindo que o tratamento combinado desses efluentes seja uma alternativa viável. Diante desse quadro, este trabalho visou à avaliação do tratamento combinado de esgoto doméstico da estação de tratamento de efluentes (ETE) da Unisinos e lixiviado bruto do aterro sanitário de São Leopoldo, utilizando ozônio (O3) como agente oxidante. Os efluentes foram tratados na unidade experimental composta por um reservatório com capacidade de até 500L e um reator cilíndrico de PVC com 250 mm de diâmetro e 2,20 m de altura, operando com fluxo ascencional, totalizando um volume de trabalho de 108 L e preenchido em 2/3 do seu volume total com Anel Pall de 1,5”. Realizaram-se três ensaios em bateladas, com duração de cinco horas e três ensaios com duração de duas horas, com diferentes produções de O3 de 8,9; 9,6 e 10,5 g de O3.h-1, aplicados à mistura de 2% de lixiviado de aterro sanitário (LAS) ao esgoto doméstico (2 L de LAS e 158 L de esgoto). Cada ensaio foi realizado em duplicata, sendo monitorados os seguintes parâmetros: Demanda Química de Oxigênio, Demanda Bioquímica de Oxigênio, Cor Aparente e Verdadeira, Turbidez, pH e calculada as taxas de utilização e de perda de O3. Os resultados evidenciaram que o tratamento por O3 pode ser uma alternativa de pré-tratamento de efluentes, obtendo remoções médias de DQO, DBO, CA, CV e Turbidez de até 46%, 51%, 86%, 86% e 81% respectivamente em cinco horas de ensaio e remoções médias de até 23%, 48%, 78%, 76% e 58% respectivamente em duas horas de ensaio. As maiores taxas de remoções foram alcançadas nos ensaios com maiores vazões de O2 e produções de O3 e nas duas primeiras horas de ensaio. Só foi possível o atendimento aos padrões de lançamentos de efluentes exigidos pela legislação vigente, nos ensaios com duração de cinco horas e com a maior produção de O3 e vazão de O2. O sistema de tratamento também contribuiu para uma melhora na biodegradabilidade do efluente se analisada a relação DBO/DQO e cor. Quanto as taxas de utilização e de perda de O3, verificou-se que a maior quantidade consumida de O3, ocorreu para os parâmetros indicativos de matéria orgânica e para os ensaios com a menor produção de O3. / Landfill leachate has been characterized by the high concentration of recalcitrant organic matter, ammoniacal nitrogen and toxic compounds. Recalcitrant organic compounds are rarely removed by traditional effluent treatment processes. In addition, the treatment of the leachate is colloquial to meet the discharge standards of the effluent. Likewise, the domestic sewage disposal generated by the communities also needs previous treatments to avoid impacts on the environment. Due to the characteristics of domestic sewage, with low concentrations of organic carbon in relation to the leachate, it has allowed the combined treatment of these effluents to be a viable alternative. In view of this situation, this work had the objective of evaluating the combined treatment of domestic sewage of (ETP) and the raw leachate of the San Leopoldo landfill using ozone (O3) as an oxidizing agent. Three batch trials were carried out with a scheduled duration of five hours and three trials lasting two hours, with different yields of O3 of 8.9, 9.6 and 10.5 g of O3.h-1, applied to the mixture Of 2% of landfill leachate) For domestic sewage (2L of LAS and 158L of sewage). Each assay was performed in duplicate and the following parameters were monitored: Oxygen Chemical Demand, Biochemical Oxygen Demand, Apparent and True Color, Turbidity, pH and calculated O3 utilization and loss rates. The results showed that the treatment with O3 can be an excellent alternative of pretreatment of effluents, obtaining average removals of COD, BOD, CA, CV and Turbidity of up to 46%, 51%, 86%, 86% and 81 % Respectively. Average test and removal hours of up to 23%, 48%, 78%, 76% and 58%, respectively, in two hours of testing. The highest removal rates were obtained in the tests with higher flows of O2 and yields of O3 and in the first two hours of the test. It was only possible to meet the effluent release standards required by current legislation, in trials with a duration of five hours and with the highest production of O3 and O2. The treatment system also contributed to an improvement in the biodegradability of the effluent if the BOD/COD ratio was analyzed. As for the rates of use and loss of O3, it was verified that the highest amount of O3 occurred for the parameters indicative of organic matter and for the tests with lower production of O3. The higher the O3 production, the higher the O3 loss and the greater oxidant loss may have been due to volatilization in the effluent accumulation reservoir, since there was no gas loss due to Off-gas and the method used Not Detected The residual ozone.

Nos últimos anos, os processos oxidativos avançados (POAs) têm emergido como métodos potencialmente poderosos para transformar poluentes orgânicos recalcitrantes em substâncias menos tóxicas. O presente trabalho visa estudar a degradação de clorofenóis 2,4-diclorofenol (2,4-DCF) e pentaclorofenol (PCF) em solução aquosa por meio do processo foto-Fenton. Os experimentos foram realizados em um reator fotoquímico, em regime batelada, com recirculação e admissão contínua de peróxido de hidrogênio. Os efeitos das concentrações iniciais de clorofenóis, H2O2 e Fe(II), bem como, da potência da lâmpada de vapor de mercúrio, foram estudados a partir de um planejamento experimental Doehlert em multiplos níveis e analisados segundo a metodologia de superfícies de respostas. A foto-oxidação foi monitorada por medidas da concentração de carbono orgânico total (TOC) e do espectro de absorção da solução ao longo do tempo e, em alguns casos, medidas de toxicidade por meio de bioensaios com Artemia sp. Os resultados dos experimentos realizados com 2,4-DCF evidenciaram degradação gradativa, com remoções de TOC superiores a 99%, após 1 hora de tratamento, além de remoção de toxicidade, mesmo para altas concentrações iniciais do poluente (até ca. 415 mgC L-1). Nos experimentos realizados com PCF observouse decaimento inicial de TOC bastante rápido (15 minutos), o que sugere que a degradação dos clorofenóis torna-se mais rápida com o aumento do número de átomos de cloro ligados ao anel aromático. Foi removida mais da metade do TOC inicial por volta de 30 minutos de reação, obtendo-se remoções de até 90,8% ao final do tratamento. Por outro lado, comparado ao 2,4-DCF, no caso do PCF observou-se redução acentuada da taxa de remoção de TOC após esse tempo, o que pode ser explicado a partir da maior concentração de íons cloreto em solução, da formação de complexo estável desses íons com Fe(III) e de espécies geradas a partir de reações envolvendo esse complexo. No conjunto, os resultados comprovam a viabilidade do processo foto-Fenton para remediação de efluentes aquosos contendo clorofenóis. / In recent years, advanced oxidation processes (AOP) have emerged as potentially powerful methods to transforming organic pollutants into harmless substances. The present work aims to study the degradation of chlorophenols (2,4-dichlorophenol and pentachlorophenol) in aqueous solution by the photo-Fenton process. The experiments were conducted in a batch recycle photochemical reactor with continuous feed of hydrogen peroxide solution. The effects of the initial concentrations of chlorophenols, H2O2, and Fe(II), as well as of the electric power of mercury vapor lamp, were studied by means of a Doehlert multivariate experimental design at multiple levels. Experimental results were analyzed according to the response surface methodology. In order to characterize the degradation of the pollutant, time-measurements of the total organic carbon concentration (TOC) as well as the absorbance spectra of the solution, were carried out. In some cases toxicity bioassays were carried out with Artemia sp. The results obtained from experiments with 2,4-dichlorophenol showed a gradual degradation, with more than 99% of TOC removals after 1 hour of treatment, along with toxicity removal, even for high initial pollutant concentrations (ca. 415 mgC L-1). In the case of pentachlorophenol, a fast initial TOC decrease (around 15 minutes) was observed, suggesting that chlorophenols degradation becomes faster with the increment of chloro atoms number bounded to the aromatic ring. More than a half of the initial TOC was removed around 30 minutes of reaction, rising 90.8% of TOC removal at the end of the treatment. In the other hand, comparing to 2,4-DCF, for PCF a marked reduction of the maximum rate of TOC removal after that time. This can be explained by higher concentrations of chloride ions in the solution, for the formation of stable complexes with Fe(III) ion and resulting species in reaction involving such complexes. As a whole, the results confirm the effectiveness of the photo-Fenton process for the remediation of aqueous solutions containing chlorophenols.

This PhD thesis investigated solid and liquid waste treatment systems for Sureclean, a waste Management company based in the North of Scotland. Sureclean receives a diverse range of waste streams and the increasing need for sustainable development as well as stringent environmental legislation motivated this research to develop an integrated waste treatment system. Waste characterisation was conducted using a range of analytical instrumentation to identify the TPH, COD, heavy metals content, TOC, and particle size of Sureclean waste streams. From there, four treatment systems were investigated utilising Sureclean waste streams: mechanical separation, chemical treatment, electro-coagulation and the advanced oxidation process. Laboratory and field trials were conducted using these different treatment techniques and the analysis was performed to verify the treatment results. The result of these trials led to the development of four modular waste treatment units, that form the outcome of this research: the Sureclean Water Treatment System (SWTS), a filtration based mechanical separation system was shown to reduce the TSS, BOD and TOC content of an oily wastewater; the Sureclean Sludge Separation System (SSSTS), a chemical-enhanced filtration based system was demonstrated to reduce 52.6 % of the sewage sludge volume; the Sureclean Electro-coagulation Water Treatment System (SEWTS), a system that agglomerates colloid particles and demulsifies oil removed 99.9 % of TPH from Sureclean interceptor effluent; and the Sureclean Advanced Water Treatment System (SAWTS), an advanced oxidation process which was demonstrated to reduce the TPH of a contaminated groundwater collected from an ex-gas work. The treated effluent could be discharged to Sureclean interceptor. The four treatment units developed in this research expanded Sureclean waste treatment capabilities and an integrated system was developed to treat different waste streams and to improve the treatment efficiency thus increasing the revenue and future waste stream options for Sureclean.

No processo UV/H2O2, oxidar o substrato a CO2 e água resulta em um elevado consumo de H2O2. Então, esse processo tem sido proposto como um pré-tratamento para reduzir a toxicidade a níveis seguros para o tratamento biológico posterior. Por essa razão, é necessário estudar o progresso da reação, pois a toxicidade de alguns intermediários formados durante a oxidação pode ser mais elevada que a do composto inicial. Neste trabalho, os experimentos foram realizados em um reator tubular fotoquímico, contendo em seu eixo uma lâmpada de vapor de mercúrio de baixa pressão, conectado a um tanque de recirculação. O processo UV/H 2O2 é aplicado no tratamento de água contendo fenol (50500mg C.L-1). Os resultados demonstraram que o principal produto da oxidação primária é o catecol, indicando que a hidroxilação ocorre predominantemente na posição orto. A abertura do anel aromático leva à formação de ácidos orgânicos, o que explica a diminuição do pH durante a reação. Foram identificados os seguintes ácidos: fórmico, oxálico, maleico e malônico. Na etapa seguinte desse trabalho, dois modelos cinéticos foram desenvolvidos. Os modelos foram baseados nas reações químicas e fotoquímicas iniciadas pelos radicais hidroxila gerados pela fotólise do peróxido de hidrogênio. Foram utilizados os valores encontrados na literatura para os parâmetros fotoquímicos e constantes cinéticas das reações fotoquímicas. Os resultados experimentais foram utilizados para estimar as constantes cinéticas das reações que envolvem os compostos aromáticos. No primeiro modelo foram contempladas todas as reações fotoquímicas envolvidas e, no segundo, apenas as consideradas mais significantes. Os resultados das simulações considerando os parâmetros ajustados mostraram uma melhor concordância com os dados experimentais para o primeiro modelo. As constantes cinéticas deste modelo para as reações nas quais o fenol é oxidado a catecol (k14) e hidroquinona (k15) foram 2,60x108L.mol-1.s-1 e 1,03x108L.mol-1.s-1, respectivamente. As constantes cinéticas para a oxidação do catecol (k17) e hidroquinona (k18) encontradas foram 1,41x108L.mol-1.s-1 e 2,02x108L.mol-1.s-1, respectivamente. Também foi observada elevada correlação entre as constantes k14 e k17 e entre k15 e k18. / In the UV/H2O2 process, the oxidation of the substrate to CO2 and water results in high H2O2 consumption. Due to this fact the process has been proposed as a pretreatment to reduce toxicity to safe levels prior to biological treatment. Thus, it is necessary to study the reaction progress because some intermediate compounds may be more toxic than the initial compound. In the present study experiments were carried out in a lab-scale tubular photochemical reactor with a low-pressure mercury vapor lamp placed in its axis, connected to a recirculation tank. The UV/H2O2 process was applied to the degradation of an aqueous solution containing phenol as a model pollutant (concentration range: 50-500mg.L-1). The experimental results indicated that orto-hydroxylation (catechol formation) was predominant. The cleavage of the aromatic ring resulted in the production of organic acids, which caused the pH decrease over the reaction time. The following acids were detected: formic, oxalic, maleic and malonic. The experimental results were used to estimate kinetic rate constants for the reactions involving aromatic compounds according to two kinetic models based on chemical and photochemical reactions, initiated by hydrogen peroxide photolysis to produce hydroxyl radical. Numerical values of chemical reaction rate constants and photochemical parameters were taken from literature. The first model considered all photochemical while the second model considered the most significant ones. The parameter fitting results showed better agreement with experimental values based on the first model. The resulting values for the rate constants according to this model were as follows: 2.60x108L.mol-1.s-1 for phenol oxidation to catechol, and 1.03x108L.mol-1.s-1 for phenol oxidation to hydroquinone by hydrogen peroxide. The reaction rate constants for the oxidation of catechol, and hydroquinone by hydrogen peroxide are 1.41x108L.mol-1.s-1 and 2.01x108L.mol-1.s-1, respectively. A high correlation was observed between constants k14 and k17, and between k15 and k18.

O efluente fenólico em estudo apresenta a relação DBO5/DQO (Demanda Bioquímica de Oxigênio/ Demanda Química de Oxigênio) igual a 0,15, ou seja caracteriza-se por ser um efluente não biodegradável. No tratamento inicial do efluente utilizou-se ozônio, na presença do sal de ferro II proveniente da solução de sulfato ferroso heptaidratado 0,82 mol. L-1 e do peróxido de hidrogênio , que possui a finalidade catalítica na formação dos radicais hidroxilas, com alto poder de oxidação da matéria orgânica. Nesta etapa foi estudado a união dos processos oxidativos O3/UV e Foto-Fenton, Foram tratados 3 L do efluente fenólico in natura em um reator fotocatalítico com lâmpada ultravioleta. Em todos os experimentos o pH e a temperatura do meio reacional foram controlados. Os experimentos foram executados segundo um planejamento de Taguchi L16, no qual a variável entrada de maior importância para a degradação da matéria orgânica foi o peróxido de hidrogênio. As variáveis respostas analisadas foram a concentração do Carbono Orgânico Total, Demanda Química de Oxigênio e Fenóis Totais. No planejamento de Taguchi L16 foram selecionadas as variáveis significativas para o processo de degradação do efluente fenólico, a fim de serem otimizadas através do Método de Superfície de Resposta (MSR Foto-Fenton e O3/UV). O método de otimização MSR Foto-Fenton foi eficiente na degradação do composto fenólico, sendo assim a melhor condição experimental da planilha de otimização foi a de número 10 e corresponde a uma redução de COT= 54,68%, DQO=78,73% e Fenois Totais= 98,1%. Os parâmetros controlados do processo para essa condição foram: pH=3, temperatura de 30 ºC, potência ultravioleta de 28 W e reagente Fenton (H2O2= 48,3g e Fe+2 =5,95g), que corresponde a relação mássica H2O2 /Fe+2 igual a 8. / The phenolic effluent in this study has the rate DBO5/DQO (Biochemical Oxygen Demand / Biochemical Oxygen Demand) equal to 0.15, which is characterized by an effluent to be non-biodegradable. In the initial treatment of phenol was used ozone in the presence of iron salt II from the solution of ferrous sulfate heptahydrate 0.82 mol. L-1 and hydrogen peroxide, which has the purpose in the catalytic formation of hydroxyl radicals with high oxidation power of organic matter. In this stage, was studied the union of the oxidative process O3/UV and Photo-Fenton. The effluent was treated about 3 L about in a photocatalytic reactor with UV lamp. In all experiments, the pH and temperature of the reaction medium were control. The experiments are being carried out to a Taguchi L16 design, in which the input variable of greatest importance to the degradation of organic matter was hydrogen peroxide. The response variable analyzed was given by the concentration of Total Organic Carbon (TOC) and Chemical Oxygen Demand (COD) and Total Phenols (FT). In planning Taguchi L16 significant variables were selected for the degradation process of phenolic wastewater in with purpose of to be optimized by Response Surface Method (RSM Photo-Fenton and O3/UV). The optimization method was efficient photo-Fenton degradation of phenolic compound, so the best experimental condition spreadsheet optimization was the number 10 and corresponds to a reduction of TOC = 54.68%, COD = 78,73% and Total Phenols= 98.1%. The controlled process parameters for this condition were: pH = 3, temperature of 30 ° C, power of 28 W ultraviolet and Fenton reagent (H2O2= 48,3g and Fe+2 = 5,95g), corresponding to mass ratio H2O2 / Fe +2 = 8.