Anaerobic digestion is a biochemical process that transforms diverse categories of biomass feedstock to renewable energy, in the form of methane, and contributes to resources conservation and greenhouse gases emission mitigation. Lipid-rich waste and wastewaters have a high energy potential, however efficient methane recovery with conventional anaerobic digestion technology is not easy to achieve because of a wide assortment of operational problems mainly related to the accumulation of long chain fatty acids (LCFA), products of lipids hydrolysis, in the system. The objective of the present dissertation is to test and to evaluate new methodologies and strategies to improve the anaerobic digestion of high-strength lipid waste. In a preliminary approach, the suitability and the attractiveness of high-strength lipid wastes and slaughterhouse wastes for biogas production was confirmed, suffice to control the applied organic load. The obtained results reinforced the existing knowledge describing the flotation and wash-out of substrate/biomass and the inhibition phenomena affecting the microbial population, as the main process drawbacks. The results of studies submitting anaerobic reactors to increasing concentrations of lipids/LCFA underlined the importance of the adsorption of LCFA onto the microbial cell membrane as limiting factor, guiding further research to found new technical approaches in order to control the biomass-LCFA adsorption dynamics. The use of inorganic adsorbents to capture LCFA prior to the anaerobic digestion process or the application of sequential low-energy ultrasonic pulses in order to control the adsorption-desorption kinetics were tested with interesting results. However, the effectiveness of these strategies was limited by the proportion of inorganic adsorbent/LCFA and the cumulative damaging effect of ultrasonic treatment over biomass, respectively. Further studies are thus required to optimize the efficiency and the applicability of these strategies. Efficient conversion of complex high-strength lipid waste to methane was proved to be possible in a novel reactor system configuration combining saponification pre-treatment and digested solids recirculation to the anaerobic digestion process, to increase solids retention time. A start-up step consisting on pulse-feeding cycles of the fatty waste prior to the semi-continuous process promoted an adapted microbial community for LCFA mineralization. The feasibility of this system configuration for solid slaughterhouse fatty waste was evidenced at lab scale reactors, reaching organic matter removal efficiencies higher than 90%. The comparison of this configuration with systems without saponification or without digested solids recirculation confirmed the synergistic effect of both strategies. The use of high throughput sequencing approach (454-pyrosequencing) to characterize the evolution of the biodiversity and the phylogenetic structure of the microbial community during the operation of the tested configurations concluded that a selection of a defined functional acidogenic population (ß-oxidizers) was induced by substrate pretreatment. Contrary, the solids recirculation resulted in an enrichment of the methanogenic biodiversity, mainly of hydrogenotrophic archaea. Based on the satisfactory results obtained with the strategies studied in the present dissertation, it is expected that lipid-rich waste valorization will be a real alternative to increase renewable energy production through anaerobic digestion process.

Una de las principales fuentes de contaminación de las aguas es el vertido de efluentes insuficientemente depurados, razón por la que el control de vertidos ha centrado gran parte de las actuaciones legislativas de las administraciones competentes en esta materia. Las técnicas convencionales de depuración de metales pesados presentan dificultades para lograr el cumplimiento de los límites de vertido siendo necesaria la búsqueda de técnicas alternativas para reducir estas emisiones. En este sentido, la investigación en bioadsorción ha mostrado en los últimos años el potencial de esta tecnología para el tratamiento de aguas contaminadas por metales pesados. El objetivo de la tesis doctoral es el estudio de la bioadsorción como tecnología para el tratamiento de aguas residuales industriales contaminadas con metales pesados utilizando Posidonia oceanica y turba como bioadsorbentes. Para ello se ha implementado una metodología dirigida al desarrollo de una herramienta de predicción del proceso de bioadsorción en lecho fijo y a la evaluación de la potencial aplicación del proceso a nivel industrial. La presentación de resultados se inicia con el estudio experimental dirigido a la evaluación del uso de la Posidonia oceanica y de la turba para la eliminación de cobre en aguas. Tras determinar las características físico-químicas de ambos bioadsorbentes, se han evaluado los mecanismos de interacción con el cobre. Se presenta la caracterización del equilibrio de adsorción tanto en discontinuo como en la operación dinámica en columnas de lecho fijo. El empleo de una técnica de estímulo-respuesta ha permitido determinar los valores del coeficiente de dispersión hidrodinámica y su variación con la velocidad intersticial del fluido en lechos de ambos bioadsorbentes. La presencia de agentes complejantes en las aguas residuales puede ocasionar interferencias en los tratamientos de depuración convencionales. Por ello, se analiza el efecto de la presencia de EDTA, seleccionado como agente complejante típico, sobre el rendimiento del proceso. Asimismo, se analiza la reutilización de los bioadsorbentes en ciclos consecutivos de adsorción-desorción. A continuación se presenta el modelo matemático desarrollado con el fin de obtener una herramienta para la simulación de la bioadsorción de metales pesados en columna de lecho fijo. La calibración del modelo se ha realizado utilizando los datos de los ensayos de bioadsorción de cobre en columna de lecho fijo sobre Posidonia oceanica y sobre la turba, y ha permitido la estimación del coeficiente de transferencia de materia interna en estos sistemas. Con la validación del modelo, realizada a partir de experimentos independientes a los utilizados en la fase de calibración, se corroboran las hipótesis del modelo. Asimismo, se incluye un análisis de sensibilidad del modelo mostrando la influencia del coeficiente de dispersión hidrodinámica y del coeficiente de transferencia de materia interna sobre los resultados de las predicciones del modelo. El trabajo se completa con ensayos realizados en el marco de un proyecto de investigación aplicada, financiado por el Instituto Tecnológico Metal-Mecánico (AIMME) para evaluar la aplicación de la tecnología en el sector de tratamiento de superficies. Se presenta un estudio comparativo del rendimiento de la operación sobre diversos materiales incluyendo la Posidonia oceanica y la turba, otros bioadsorbentes (chitosan y chitín) y dos carbones activados comerciales, utilizando cobre o níquel como metales pesados de referencia en las aguas residuales de este sector. El estudio incluye la evaluación de la bioadsorción para el tratamiento de aguas residuales aportadas por una empresa del sector de tratamiento de superficies metálicas. Por último, se analizan los resultados del estudio de una configuración de columnas en serie utilizando un lecho de bioadsorbente seguido de un lecho de carbón activado como alternativa para el tratamiento de aguas contaminadas con metales pesados en presencia de agentes complejantes. / The objective of this doctoral thesis is to study biosorption technology for treatment of wastewater polluted with heavy metals using Posidonia oceanica and peat as biosorbents. For this purpose, a methodology has been implemented to develop a fixed-bed performance prediction tool and to evaluate the industrial application of biosorption technology. Posidonia oceanica and peat are tested for copper removal from wastewater. Physicochemical properties of both biosorbents and mechanisms involved in copper retention are evaluated. Equilibrium results in batch and dynamic conditions in fixed-bed columns are presented. Hydrodynamic characterisation of biosorbent beds has been achieved with a stimulus-response technique and consequently the hydrodynamic dispersion coefficient and its variation with fluid interstitial velocity have been obtained. The effect of the presence of EDTA in the feed solution of the column was investigated for both biosorbents from an industrial application perspective. Likewise, reutilisation of biosorbents was evaluated in adsorption−desorption cycles. A mathematical model has been developed as a simulation tool for heavy metal biosorption fixed-bed processes. Model calibration is carried out using experimental results of copper biosorption in fixed-bed columns, which allows the intraparticle mass transfer coefficient to be estimated. Experimental results obtained in independent biosorption experiments were used to model validation, corroborating model hypothesis. Finally, the influence of hydrodynamic dispersion coefficient and intraparticle mass transfer coefficient on simulation results is evaluated with a sensitivity analysis. The thesis is completed with a study carried out as a part of a research project focused on the industrial application of the technology. The experimental design was developed to evaluate biosorption technology to treat industrial wastewater from surface treatment facilities, whose main characteristic is the presence of complexing agents. The copper and nickel biosorption performance of Posidonia oceanica and peat is compared with those of other biosorbents (chitosan and chitin) and with two activated carbons. Sorbent performances were also checked using industrial wastewater of a representative facility of the surface treatment sector. A serial column configuration with a biosorbent bed of Posidonia oceanica or peat coupled with an activated carbon bed was evaluated as an alternative configuration for heavy metal with complexing agent wastewater treatment.

This thesis investigates the use, safety and regulation of the plasticisers, epoxidised soya bean oil (ESBO), acetyl tributyl citrate (ATBC) and di-(2-ethylhexyl) adipate (DEHA), which are used in food contact plastics. The thesis analyses the scientific evidence concerning the toxicity and migration of these plasticisers and the selection and interpretation of that evidence by relevant national and international expert committees and organisations in the UK and EC. The history of the control of these plasticisers is also examined in the context of an analysis of the general control of this sector in the UK and the EC from the 1950s to the 1990s. This investigation is located against the background of a review of the literature on the role that science can play in the policymaking process, and how social, political and economic factors may be structured into the process of expert evaluation of scientific evidence and risk assessment. The complex details of the chosen examples provide evidence that there are considerable uncertainties concerning the safety of these plasticisers. In the absence of adequate evidence of safety, it is concluded that historically, the benefit of the doubt has been consistently awarded in favour of the continued use of these plasticisers rather than in the cautious protection of public health. The further conclusion is drawn that the policy-process has been generally inadequate in this field in order to ensure adequate protection of public health. Evidence is presented which shows that the outcome of expert evaluation and policy-making in this field can be related to assumptions that have been made which have an identifiable political and economic basis. It is therefore concluded that there is a case for changes in the policy-making institutions and processes in order more effectively to protect public health.

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This study identifies the major environmental issues and problems affecting Zambia and examines the current state and practice of environmental protection and management. A review of the existing legislation relating to environmental protection in Zambia is made. The relationship between the development process and the environment is explored, in particular giving an overview of the evolution of paradigms in environmental management and development. An outline of the environmental trends in sub- Saharan Africa and the environmental policy in the United Kingdom and how it relates to the framework of EC environmental policy is made. With such a background key issues have been identified to be addressed when considering environmental policy in Zambia. The mining, agricultural and tourism industries form the sectoral case studies of this study. These sectors have been selected on the basis of their dominance in Zambia's development strategy and their impact on the environment. The immense scale of the mining industry warrants its consideration; agriculture has now been given priority as the sector with the highest potential in the overall economy and; in diversifying the economy, tourism development is emerging as one of the most important sectors. The study recognises that the absence of definite crosssectoral guidelines for environmental resources management and a general paucity of information on the environment have been major constraints for the development of environmental protection strategies in Zambia. This has been due to insufficient institutional support for sustained research and monitoring of the environment. Therefore, the study mak?s general sectoral recommendations for addressing the environmental problems identified in the study.

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