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Pharmaceuticals have been detected in natural waters for more than forty years, but with improvements in sample preparation procedures and analytical instrumentation, the number of scientific publications on the issue has increased significantly. Even though the concentration of pharmaceutical residues in surface and drinking water is not critical for human health according to the present level of knowledge, the consequences for the environment are not clear. Wastewater treatment plants (WWTPs) have been identified as the primary route of pharmaceuticals to the environment, with households as the major source point for most of the over-the-counter and prescription drugs. In this thesis, the first aim was to study the occurrence, fate and removal of 43 pharmaceuticals during conventional wastewater treatment. The target compounds were selected on the basis of their high consumption in Spain or/and frequently reported detection in wastewaters and the possibility to be analyzed under the same experimental conditions. They belong to different therapeutic classes, i.e. nonsteroidal anti-inflammatory agents and analgesics, lipid modifying agents, psycholeptic and antiepileptic drugs, beta-blocking agents, beta-2-adrenoreceptor agonists, H2-receptor antagonists, antibiotics, angiotensin converting enzyme agents, diuretics and antidiabetic drugs. A wide variation in removal efficiencies was observed even for individual compounds, and across therapeutic classes and treatment processes, without clear conclusion on the removal of any particular compound. According to mass balance calculations and estimated partition coefficients, the loss of the selected pharmaceuticals during biological wastewater treatment can be fully attributed to biodegradation/biotransformation. None of the studied compounds was entirely biodegraded and/or transformed during biological wastewater treatment, but the measured concentrations were below the levels of concern according to available toxicity data. Conventional WWTPs cannot be expected to be the only mechanism for controlling the entry of pharmaceuticals into the environment because they were neither designed nor can provide their complete removal. Therefore, the challenge is to look for solutions that would be the most economical and effective means of preventing further pollution of natural waters by pharmaceuticals. More appropriate management of sewage waters before they enter treatment plants as well as a stricter control of effluent discharges, along with an in-depth investigation on the development of new designs and strategies for the improvement of existing wastewater treatments should be considered. In light of this, as the second objective of this thesis, alternative approaches for the removal of the antiepileptic carbamazepine (CBZ) were studied in aqueous media in two laboratory scale experiments: a) biodegradation using white rot fungus T. versicolor in an air-pulsed fluidized bioreactor operated in batch and continuous modes, and b) advanced oxidation using TiO2-heterogeneous photocatalysis under simulated solar and UV-A irradiation, and under the combined use of ultrasound and UV-A irradiation (sonophotocatalysis). We selected CBZ as a representative example of compounds that are found to be refractory to biological treatment and ubiquitous in various environmental matrices. Both, the fungal and UVA-driven TiO2-photocatalytic treatments, very different in their nature, have been shown to be very effective in degrading carbamazepine in aqueous media. The fungal treatment resulted in average removals of 54 and 96% in batch and continuous reactor, respectively. Acute toxicity test using the bioluminescent marine bacterium Vibrio fischeri showed a decrease in toxicity during the treatment in both types of bioreactor. In the other study, initial CBZ concentrations were reduced for 95% during 120 min of the UV-driven photocatalytic experiment and sonophotocatalysis, while only 10 % of CBZ was photodegraded during under solar irradiation. A slight increase in toxicity in Daphnia magna acute toxicity testing was observed over the time-course of the photocatalytic experiments, which can be associated with the formation of transformation products of CBZ. Ultraperformance liquid chromatography coupled to a quadrupole-time-of-flight mass spectrometry was used for a tentative identification of the transformation products of CBZ formed during the performed experiments. Most of the tentatively identified intermediates exhibited only slight modifications of the CBZ molecular structure. The fungal as well as the photocatalytic processes yielded oxygenated transformation products. In the biological treatment using T. versicolor, transformation products were formed by enzymatic epoxidation and hydroxylation of seven-membered heterocyclic ring of the carbamazepine molecule. During the photocatalytic experiments, CBZ-related transformation products emerged from hydroxylation and further oxidation of different parts of the molecule of carbamazepine. The generated transformation products appeared to be more persistent than their parent compound, as they were present, although at low concentration, until the end of the experiments. The results of the thesis contribute to a better understanding of a) the magnitude of the selected pharmaceuticals that reach the environment through the wastewater and sludge discharge, b) the efficiency of typical conventional wastewater treatment plants regarding the removal of these compounds from raw wastewater, and c) possible developments of alternative technologies for their enhanced elimination. / Desde hace más de cuarenta años se ha detectado la presencia de fármacos en el ciclo de aguas, sobre todo debido a los avances en la química analítica que han permitido el desarrollo de nuevas metodologías analíticas para la determinación de estos compuestos de modo fiable y a bajas concentraciones. Las estaciones depuradoras de aguas residuales (EDARs) han sido identificadas como la ruta principal de entrada de fármacos de origen humano en el medioambiente. Por tanto, el principal objetivo de esta tesis ha sido el estudio de la presencia, destino y eliminación de 43 fármacos seleccionados, durante el tratamiento convencional realizado en las EDARs. Los compuestos estudiados fueron seleccionados en base a los índices de consumo en España, a la frecuencia de detección en aguas residuales y además en base a la posibilidad de ser analizados bajo las mismas condiciones experimentales. Estos compuestos pertenecen a diferentes clases terapéuticas, i.e. antiinflamatorios no esteroideos , los agentes que reducen los lípidos séricos, ansiolíticos y antiepilépticos, los agentes bloqueadores beta-adrenérgicos, agonistas β2 adrenérgico, antagonistas H2 , antibióticos, inhibidores de la enzima convertidora de angiotensina, diuréticos y antidiabéticos. Para el análisis cuantitativo se utilizó la cromatografía de líquidos acoplada a espectrometría de masas en tándem (LC-MS/MS), empleando un sistema híbrido triple quadrupolo/trampa de iones lineal. Como segundo objetivo hemos considerado evaluar tratamientos avanzados alternativos al tratamiento convencional para la eliminación de un fármaco antiepiléptico, la carbamazepina, uno de los compuestos más recalcitrantes al tratamiento biológico convencional. Se procedió a estudiar su degradación en medio acuoso mediante dos procedimientos a escala laboratorio: a) biodegradación utilizando el hongo ligninolitico Trametes Versicolor en un reactor fluidizado por pulsos de aire operando en modo batch y continuo, y b) oxidación avanzada mediante un tratamiento fotocatalitico en presencia de TiO2 bajo irradiación UV-A y solar, y aplicando la radiación UV en combinación con ultrasonidos (sonofotocatálisis). Para la evaluación de los tratamientos alternativos, se identificaron los productos de transformación de la carbamazepina, y se evaluó la toxicidad de las muestras tratadas. Se utilizó la LC-MS/MS con analizador de tipo cuadrupolo-tiempo de vuelo. También se evaluó la toxicidad de las muestras tratadas.

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During the last years, the implementation of new Wastewater Treatment Plants has lead to a significant increase of sludge production. As a response, sludge valorisation in agriculture is the preferred option nowadays, ensuring the return of organic constituents, nutrients and microelements to crop fields. In practice, sludge treatments should provide a final product suitable for land application, with reasonable investment as well as operational and maintenance costs. In this sense, sludge treatment wetlands (STW) appear as a suitable technology for sludge management from an economic and environmental point of view. The main objective of this research work was to assess the suitability of STW for sludge management; with special focus on small communities of the Mediterranean Region. To this end, technical, environmental and economic aspects of the treatment were studied in 3 full-scale systems and in a pilot plant located in Catalonia. A comparison with conventional treatments for sludge management is presented in order to establish the most favourable solution for the Catalan context. As the final result from this work, design and operation criteria are proposed as a guide for STW implementation in small Mediterranean communities. The study of the performance of the full-scale STW suggests good treatment efficiency. Moisture content was reduced by 16-30%, reaching efficiencies similar to those of conventional dewatering technologies. On the other hand, VS were reduced up to 30-49%VS/TS, suggesting the progressive sludge stabilisation and mineralisation. Similar values were found at the end of the treatment in the pilot plant. In this case the sludge volume was reduced around 80% and TS increased up to 16-24%. However, the observed VS reduction (up to 50%VS/TS) after 2 months without feeding, indicates that longer resting periods should be applied in order to increase mineralisation of the sludge. A finite element model able to simulate sludge dewatering in STW was developed by combining the evapotranspiration (ET) and the Terzaghi¿s consolidation theory representing water percolation. The model allows for the determination of the most appropriate feeding frequency as a function of the sludge height stored on the wetland. Similarly, the sludge loading rate is determined as a function of ET, feeding frequency and sludge height. On the whole, the model implemented is a useful tool for the establishment of standardised criteria of STW operation. The characterisation of the final product from the pilot plant and from three full-scale systems demonstrated the suitability of biosolids as organic fertilisers. DRI values indicated the partial stabilisation of the product. Moreover, the absence of phytotoxicity and the heavy metals concentrations below the legal thresholds confirmed their viability to be reused in agriculture. However, in the pilot plant, pathogens were still present after 2 resting months, confirming the necessity of a longer resting period. Monitoring the stabilisation degree as phytotoxicity, heavy metals and pathogens' concentration during the final resting period would help optimising its duration. Looking at the environmental aspects, the static chamber method was successfully adapted to the determination of gas emissions from STW. Aerobic conditions before sludge feeding, characterised by low methane emissions and high nitrous oxide emissions, were strongly altered by fresh sludge feeding, which increases CH4 emissions and reduces N2O emissions. According to the measured emissions, the Global warming potential of STW corresponds to 17kgCO2eq/PE¿y, which is from 2 to 9 times lower than that of sludge centrifugation and transport. Besides,the economic and environmental assessment indicates STW with direct land application as the most cost-effective technique, which is also characterised by the lowest environmental impact.Thus STW are the best solution to manage waste sludge in decentralised small communities.

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D.L. A 792-2008 / Ministerio de Educación y Ciencia; Programa FEDER; Generalitat Valenciana; Universidad de Alicante.

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