Tertiary butyl alcohol (TBA) is used as a fuel oxygenate and is the main breakdown component of methyl tert butyl ether (MTBE). As such, TBA is found in water systems through storage leaks and spills, presence of MTBE in the water, and as an impure byproduct of MTBE-blended fuels. It presents several health hazards and is a suspected carcinogen. Studies involving aquatic life, mice and rats indicate that TBA is a concern at low concentrations. Wastewater removal of tert butyl alcohol (TBA) has been limited to methodology used by MTBE or by anaerobic or aerobic methods. Neither set of techniques is applicable to TBA due to its long biological degradation period, its very specific conditions for anerobic or aerobic treatment, and its low Henry's law constant, low transformation rate, and its high mobility. The main goal of this project was to determine the adsorption capabilities of different zeolites for TBA. A comparison to previous work done with powdered zeolites and MTBE is shown in the following Chapters. Batch systems of TBA and several different zeolites were examined to determine the best zeolites for TBA adsorption. As shown in Chapter 3, the best zeolites for TBA adsorption over an equilibrium time of 48 hours were silicalite and HiSiv 3000 pellets. Using the two chosen zeolites, silicalite and HiSiv 3000, adsorption isotherms were created and compared against MTBE data using the same data. The final portion of this project included a continuous system consisting of a zeolite column and a steady flow rate of TBA. The zeolite columns consisted of sole silicalite, sole HiSiv 3000, and different proportions of the two zeolites in the same column. All column experiments were run at similar conditions with variation in the adsorbent bed lengths for easy comparison between the resulting breakthrough curves. At the 3-cm bed length, the zeolite columns outperformed the activated carbon column; however, there was no distinct difference between the zeolite columns. In the 6-cm bed length experiments, there were apparent differences between the two zeolite breakthrough curves. The 9-cm column did not differentiate between the zeolites.

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This thesis presents the achievements pursued during the doctoral course. The work was carried out in the context of the project ERiCSol (Energia RInnovabile e Combustili SOLari), as part of the University of Trento strategic plan for the years 2017-2021. The project was conceived to establish an interdepartmental area to promote the challenge of developing scientific research and technological innovation to increase the competitiveness of Trento at national and international level in the areas of energy and environment. Among all the goals of the project, this work dedicates special attention to 1) development of novel materials for solar photocatalytic reactions and 2) use of renewable energy to push forward applications in water remediation. To accomplish these goals, the research brings a full collection of experimental activities regarding the employment of solar concentration for the environment industry and therefore this document is organized in 9 chapters. In chapter 1, it is presented the introduction outlining the overview of the environment industry, the employment of solar light as energy source and the general and specific objectives. Chapter 2 presents a literature review regarding the last 30 years of applications correlating the use of solar light towards wastewater purification. The chapter reviews the engineering features of solar collectors, photocatalyst materials employed and the panorama of the pollutants investigated up to the present date in solar photocatalysis, presenting comparisons between models and real wastewater approaches. Chapter 3 details the experimental techniques and characterizations employed to sustain the investigation proposed in the thesis. The first part of the chapter explains the features of parabolic dish solar concentrator designed and manufactured by the IdEA group at the physics department of the university of Trento. After, it is presented the pulsed laser deposition, a thin films fabrication technique employed to produce the photocatalysts used on water purification experiments. The second part of the chapter presents the description of the characterization techniques used to reveal the fabricated photocatalyst materials properties. Based on the review on the fundamentals of solar photocatalysis and the experimental techniques, chapters 4 and 5 present a discussion in the field of novel photocatalytic materials capable to operate under concentrated sunlight irradiation. Chapter 4 in special presents the investigation regarding the fabrication of tungsten trioxide (WO3) thin film coatings, bringing the novelty of using pulsed laser deposition as the fabrication method and the evaluation of this material in photocatalysis for the degradation of methylene blue dye model pollutant. Chapter 5 instead, presents the development on Zinc Oxide (ZnO) nanoparticles, bringing an innovative point of view on a “green-synthesis” approach and the material immobilization in film for heterogeneous photocatalysis routes. Chapters 6 and 7 discuss solar photocatalysis aiming to shift applications from model pollutants to real wastewater remediation conditions. Important comparisons are performed and discussed regarding the advantages and existing drawbacks. To fulfill this purpose, chapter 6 presents an application case of solar photocatalysis to the degradation of a surfactant-rich industrial wastewater whereas chapter 7 presents the approach focused on the remediation of organic lead contaminants present on a local water well site in the city of Trento. The last experimental approach of concentrated solar light is presented on chapter 8, dedicated to the application of concentrated sunlight towards waste biomass valorization. Conversely to the application on water previously described, this chapter presents the activity on designing, fabricating and coupling a hydrothermal reactor with concentrated sunlight using it as the driving force to promote degradation of grape seeds evolving into hydrochars with possible valorization of the carbonized material. Lastly, chapter 9 presents the conclusions and suggestions, this item expresses the final considerations on the results of the experimental investigations, advantages and limitations observed, and suggests possible actions for future works.

Algae have been the centre of recent research as a sustainable feedstock for fuel because of their higher oil yield in comparison to other plant sources. However, algae biofuel still performs poorly from an economic and environmental perspective due to the high reliance on freshwater and nutrients for cultivation, among other challenges. The use of wastewater has been suggested as a sustainable way of overcoming these challenges because wastewater can provide a source of water and nutrients for the algae. Moreover, the ability of the algae to remove contaminants from wastewater also enhances the total economic output from the cultivation. However, the success of this strategy still depends greatly on efficient strain selection, cultivation and harvesting. Therefore, this PhD thesis has focussed on strain isolation, characterisation, optimisation and cultivation in open pond systems. Five algae strains were isolated from wastewater treatment tanks at a municipal water treatment plant in North West England. The isolated strains were morphologically and genetically characterised as green single-celled microalgae: Chlamydomonas debaryana, Hindakia tetrachotoma, Chlorella luteoviridis, Parachlorella hussii and Desmodesmus subspicatus. An initial screening of these strains concluded that C. luteoviridis and P. hussii were outstanding in all comparisons and better than some of the strains previously reported in the literature. Further tests carried out to elucidate the underlying tolerance mechanisms possessed by these strains were based on stress tolerance and acclimation hypotheses. In the following experiments, C. luteoviridis and P. hussii were found to have higher anti-oxidant enzyme activity that helps in scavenging reactive oxygen species produced as a result of exposure to wastewater. This result provides a new argument for screening microalgae strains for wastewater cultivation on the basis of anti-oxidant activity. In addition, the two strains could grow heterotrophically and are better adapted to nutrient deficiency stress than the other three isolates. In order to understand the role of microalgae acclimation in wastewater cultivation, strains identical or equivalent to the wastewater treatment tank isolates were obtained from an algae culture collection. These strains had not been previously exposed to wastewater secondary effluent. The initial growth of these strains in wastewater secondary effluent was very poor. However, after two months of acclimation to increasing concentrations of secondary wastewater effluent, it was observed that growth, biomass and lipid productivities of most of the strains were significantly improved, although still not as high as the indigenous strains. Therefore, it was concluded that continuous acclimation is an additional factor to the successful growth of algae in wastewater. Furthermore, addition of 25% activated sludge centrate liquor to the secondary effluent was found to increase algal growth and biomass productivity significantly. Futher tests to examine the continous cultivation of C. luteoviridis and P. hussii in wastewater showed that a biomas productivity of 1.78 and 1.83 g L-1 d-1 can be achieved on a continual basis. Finally, the capability of C. luteoviridis and P. hussii for full seasonal cultivation in a 150 L open pond in a temperate climate was studied, using the optimised secondary wastewater +25% liquor medium. Each strain was capable of growth all year including in autumn and winter but with strongest growth, productivity and remediation characteristics in the summer and spring. They could maintain monoculture growth with no significant contamination or culture crash, demonstrating the robustness of these strains for wastewater cultivation in a northern European climate.