L’attuale condizione che caratterizza il settore energetico richiede un necessario processo di riconversione che, oltre a favorire il risparmio energetico, riduca la dipendenza dai combustibili fossili ed accresca l’impiego di fonti energetiche rinnovabili, dando un contributo fondamentale alla riduzione delle emissioni di gas serra come diversi accordi internazionali richiedono. Si rende pertanto necessario accelerare i processi che da alcuni anni stanno favorendo l’utilizzo di energia da fonti rinnovabili. Tra queste, le fonti legate ai processi di trattamento biologico dei reflui stanno avendo un interessante sviluppo. Esistono numerosi processi biologici che consentono la produzione di energia in maniera indiretta, quali ad esempio i processi di digestione anaerobica finalizzati alla produzione di biogas e/o produzione biologica di idrogeno. In tale contesto si inserisce la tecnologia delle Microbial Fuel Cell, che consente la produzione diretta di energia elettrica, finalizzata al recupero energetico inteso al miglioramento dell’efficienza energetica e alla riduzione dei costi d’esercizio di impianti di trattamento biologico dei reflui. Il presente lavoro di Tesi di Dottorato sperimentale, svoltosi in collaborazione al laboratorio PROT.-IDR. della sede ENEA di Bologna, riporta i risultati dell’attività di ricerca condotta su una MFC (Microbial Fuel Cell) a doppio stadio biologico per il trattamento di reflui ad elevato carico organico e produzione continua di energia elettrica. E’ stata provata l’applicabilità della MFC con entrambi i comparti biotici utilizzando elettrodi di grafite non trattata ottenendo, con un carico organico in ingresso di circa 9 gd-1, valori di potenza massima prodotta che si attestano su 74 mWm-2, corrente elettrica massima generata di 175 mAm-2 ad una tensione di 421 mV, ed una conversione di COD in elettricità pari a 1,2 gCODm-2d-1. I risultati sono stati molto positivi per quanto riguarda le prestazioni depurative ottenute dalla MFC. L’efficienza di depurazione misurata ha raggiunto un valore massimo del 98% di rimozione del COD in ingresso, mentre e la concentrazione di azoto ammoniacale nell’effluente raccolto all’uscita del sedimentatore è sempre stata inferiore a 1 mgN-NH4+l-1. Tra gli obiettivi posti all’inizio della sperimentazione si è rivelata di notevole interesse la valutazione del possibile utilizzo della MFC come sistema per il monitoraggio on-line del COD e degli acidi grassi volatili (VFA) prodotti all’interno di un digestore anaerobico, attraverso la definizione di una correlazione tra i dati elettrici registrati in continuo e le concentrazioni di CODanaer e VFA misurate in diversi periodi della sperimentazione. L’analisi DGGE della biomassa catodica ha fornito uno strumento analitico utile allo studio della diversità della comunità microbica sospesa ed adesa al catodo e ha confermato la forte similarità delle specie batteriche riconosciute nei campioni analizzati. In particolare, le bande di sequenziamento ottenute sono affiliate ai gruppi batterici Firmicutes, -Proteobacteria,  -Proteobacteria, -Proteobacteria e Bacteroidetes. Da quanto emerso dalla sperimentazione condotta si può pertanto concludere che ad oggi le MFC sono in fase di evoluzione rispetto ai primi prototipi utilizzati per lo studio delle comunità microbiali e per la comprensione dei meccanismi di trasferimento elettronico. Sfruttarne la potenza prodotta in maniera commerciale diviene una grande sfida per il futuro, ed è opinione comune che le prime applicazioni pratiche delle MFC saranno come fonte di recupero energetico per i dispositivi utilizzati per il monitoraggio dell’ambiente e per il trattamento delle acque reflue.

The research background and motivation of this paper is related with the role of agro-tourism impact on environment. The research background and motivation of this paper is related with the role of agro-tourism impact on environment. Agro-tourism activities impact on the development of rural area represent the reasons for it is strategic support at microeconomic and macroeconomic context. In the process of developing agro-tourism, significant attention is necessary to the environment, representing the raw material of agro-tourism activity. So, the relation among agro-tourism and environment shows a particular significance. A sustainable development and protection of the environment being the required circumstances for its practice. It is necessary realizing vital changes regarding the production and consumption of goods and services. In order to preserve our One Planet while taking into consideration economic and social aspects. Research suggests that agro-tourism sector it is a growing sector. Therefore, the link from agro-tourism and sustainable development are claiming the identification of new models by making the development more sustainable. So, this thesis proposes the approach of the influence of circular economy on the sustainable development of agro-tourism. To introduce the notion of circular economy in agro-tourism it necessary to establish and apply a sustainable development for agro-tourism structures activities. Adopting a new exemplary of management starts up with promoting new intentions related to production, consumption, ethics, etc. Circular economy in agro-tourism can lead to a sustainable use of resources for the present and future generations and accomplish sustainable development in this domain. The present research is a contribution, by questioning present issues and future potentialities, suggest ways in which agro-tourism can embrace a sustainable development with the influence of circular economy. Highlighting to focus agro-tourism structures concerning optimizing the environment by delivering major benefits for local communities and for the economy of Europe.

The hyporheic zone is often defined as the zone where mixing of surface water and groundwater occurs in shallow sediments beneath and adjacent to rivers. This mixing contributes to create unique biogeochemical conditions that may attenuate contaminants from either upstream surface water or groundwater under gaining and losing conditions. Hyporheic exchange results from differences in the channel near-bed head as it varies in space in response to interactions between surface flow and bed topography, with the interaction with the water table playing an important role too. Reactions of contaminants in groundwater also dependent on mixing between surface and subsurface water, which occurs in this zone. Therefore, representation of the profile of upwelling and downwelling exchange between surface water and groundwater have important consequences for contaminant transport. The present work studies nitrogen fate within a restored reach of the River Bure, Norfolk, United Kingdom. To this end, we confront numerical simulations of the hyporheic flow and tracer transport with field measurements of surface flow properties, nearby groundwater table and nitrogen compound concentration. We numerically model mixing between hyporheic flow paths induced by sediment, bedform, meanders on riverbed, and flow paths of adjacent upwelling of deeper groundwater. Results of the analysis indicate that despite the coarse topographical data and with limited surface water hydraulic data it is possible to define the spatial extent of hyporheic exchange and potential mixing zones for contaminants as a function of residence time. The proposed work has the potential to depict high residence time zones and biogeochemical reactivity in homogeneous and heterogeneous sediments. Furthermore, fieldwork analysis shows that in this site the hyporheic zone have a little effect on nutrient concentration. In addition, hydraulic modeling results indicate that streambed discharge significantly influences hyporheic exchange. Especially, the residence times under average stream discharge conditions are higher than the ones under the high discharge conditions mostly on the part that has riffle - pool morphology. From hydraulic point of view, heterogeneous domain has higher connectivity than the homogeneous fine sand subsurface set. Such that, subsurface flow has tendency to flow through high hydraulic conductivity zones, which is defined as tunneling effect, therefore, low conductivity zones have minor effect on hyporheic flow. The predictions based on the DaO2 index proves that heterogeneous sediment formations have more aerobic potential, however, prevailing anaerobic conditions occur mostly vicinity of low hydraulic conductivity zones.

The use of Constructed Wetlands (CWs) has been increasing over the last twenty years for decentralized wastewater treatment projects (e.g. rural communities, isolated houses, etc.) because of the low maintenance requirements and operational costs, efficiency in terms of organic matter, nitrogen and suspended solid removal. Nevertheless, the application of these systems in mountain areas is faced with some issues related to the specific characteristics of these areas, namely: the complex morphology with steep slopes and limited extensions of flat land, low temperatures and, in tourist contexts, population variations throughout the year. Limited availability of suitable land is a key issue for the application of a technology requiring considerable surfaces to produce effluents of good quality. Land area requirements constitute a well-known problem of CWs that is related to a lack of knowledge on the biological reactions occurring inside the bed. In fact, usually CWs are designed by considering simple first order decay models and specific surface area requirements, while the real requirements are not taken into account, leading most of the times to an overestimation of the area required. The limited knowledge on the processes and relative efficiencies of CW leads to overdesign of CW, mainly in low temperatures contexts and where there is a fluctuation on the resident population. Despite the efficiency that could be achieved through overestimation, those systems would be underutilized for a large part of the year. Ultimately, overestimated CWs consume more land than needed, eventually leading to the decision of switching to other systems. This research aims to identify approaches and configurations that may improve the applicability of CWs for wastewater treatment of mountain communities. These approaches try to overcome the cross-cutting issue of land area requirement, as well as those related to the variation of temperature and population through the year. This was done by exploring the use of respirometric techniques for the estimation of kinetic and stoichiometric reactions inside the bed and by testing, in a pilot plant, the influence of the tourist presence and low temperatures on the efficiency of innovative CW configurations. The research was developed at both the lab and the field scale. At the lab scale, two different tests were used in order to estimate the oxygen consumption in CW filter material: liquid respirometry and the off-gas technique. Liquid respirometry proved to be a reliable method when used to measure kinetic and stoichiometric parameters of the CW’s biomass. The off-gas technique was applied at the lab scale showing promising results, though further research is needed to improve the applicability of the method to CWs. Along with that, at the lab scale, a modified AUR method was applied on the CW material to quantify the nitrification rate of real systems at different temperatures and therefore to predict the removal efficiency throughout the year. At the field scale, several tests were performed in a pilot plant composed by two hybrid CWs (VSSF+HSSF). Among these: operation under continuous and discontinuous winter conditions, operation with overload during the summer (to simulate the presence of tourists) and the application of innovative configurations (Recirculated and Aerated VSSF). All these tests were designed with the purpose of dealing with the trade-off between the reduction of a CW’s land area requirement and the enhancement of its efficiency. Two innovative configurations were tested in the pilot plant: Recirculated VSSF CW and Aerated VSSF CW. Both configurations can provide saturated and unsaturated conditions, which allow the nitrification/denitrification inside the bed. During the period when experimental configurations were tested, the traditional VSSF CW was operated with an average specific surface area to 3.5 m2/PE, the Recirculated VSSF of 1.5 m2/PE and the Aerated VSSF of 1.9 m2/PE on average. The results showed that the CW’s surface can be considerably reduced without a significant reduction in the removal efficiency. The extra investment needed to equip VSSF CWs with aeration/recirculation would be compensated by a lower area requirement. This study explored some of the problems associated with the application of traditional CWs under the physical and social conditions that characterize mountain contexts, providing important information for future research and application. First of all, a reliable tool, the respirometric technique, was explored for the estimation of kinetic and stoichiometric parameters that will allow a more precise estimation of the land area required for these systems. Moreover, two innovative configurations (the use of recirculation and aeration in CWs) were proposed to be used where traditional configurations, though well designed, are still too large to be applied. Such configurations can also be used as a temporary solution to increase the treatment capacity during tourist peak seasons, while a traditional configuration is kept over the rest of the year. While this research focused on mountain environments, the configurations and results contained therein could be applied to a wide variety of settings where shortage of land or difficult climate conditions would exclude CWs from the list of wastewater treatment options available.

Biological nitrogen removal from strong ammonium wastewaters received a great deal of attention during the last years. Since the discovery of anammox bacteria the traditional theory of biological nitrogen removal has been extended to new nitrogen metabolic pathways. This thesis deals with the study of Simultaneous partial Nitritation, Anammox and Denitrification (SNAD) process in a Sequencing Batch Reactor (SBR) to treat wastewaters with a high ammonium load and low biodegradable organic matter, such as anaerobic digester effluent and old landfill leachate. The bacterial diversity in the reactor was investigated by analysis of specific gene clone libraries, Polymerase Chain Reaction (PCR) and fluorescence in situ hybridization (FISH). SNAD process is a complex biological process where different populations with opposed environmental requirements coexist, thus, experiments have been performed with a lab – scale reactor, focusing on the assessment of the feasibility of SBR configuration for achieving a simultaneous carbon and nitrogen removal. In addition, proper operational conditions, control strategies and a suitable loads were investigated.

Conventional Activated Sludge (CAS) systems have been widely implemented to treat wastewater. CAS systems produce huge amounts of waste sludge and its subsequent treatment represents up to 65 % of the operational costs of Waste Water Treatment Plants. The final disposal of sludge is usually performed by landfilling or incineration, involving severe environmental issues. In order to reduce sludge amount, many studies have been conducted, developing new technologies. One of these technologies is HydroThermal Carbonisation (HTC), where sludge is heated up to 180-250 °C at water vapour pressure producing a solid product enriched in carbon for different possible exploitations. The aim of this work is to apply HTC to different kinds of sludge such as thickened sludge, digested sludge and dewatered sludge and compare the behaviour of the solid and liquid phases produced by the process. For the purpose, experimental tests were performed at different operating conditions in a lab batch reactor capable to withstand high pressure (140 bar) and temperature (300 °C). In order to compare the HTC products of the different kinds of sludge, the hydrochars from HTC at different operative conditions were characterized in order to explore possible application of hydrochar and HTC process water.

Structural Health Monitoring is an important aspect in civil engineering, dedicated to monitor and maintain the structural conditions of civil architecture objects. It results in extension of their life time and appropriateness for human use. Present, commercially available sensors for SHM are complex, sophisticated and multicomponent systems. Although, they provide high precision of measurements, their total cost (the price and costs of exploitation) has been still too high to be commonly applicable. There are also other disadvantages such as distributed architecture, heavy cables or their sensitivity to electromagnetic interference like it is in case of conventional electrical sensors. Unlike them, more advance fiber optic sensors are robust to external fields. However, they involve the infrared light for data transmission, therefore they desire additional support of other devices for data processing. Now a day, there is a lack of portable sensing instruments supporting more sophisticated technologies, whose applications can be reduced by failure assessing with those instruments. Current investigations have been focused on development of structures that can be used as an independent sensing tool without a power supplier, such as mechanochromic photonic crystals with three-dimensional structure. Their mechanochromic properties are visible with naked eye as a color variation on their top surface stimulated by mechanical deformation of the structure. However, their fabrication desires high precision to obtain sample with the high sensitivity to stretching and omit some limitation corresponding to its composition (deeply described in chapter 4). Hence, there is need to find alternative solutions. One of them refers to two-dimensional photonic crystals, which were intensively investigated as a components of sensing systems such as MOEMSs (micro-opto-electro-mechanical microsystems). However, their main disadvantage is the fabrication that involves the lithography techniques, which are quiet expensive and time-consuming. Furthermore, the lithographic techniques desire clean room conditions. Hence, the number of produced specimens is limited. In this thesis, there is proposed completely new approach to develop a strain sensor, including fabrication of strain-sensitive sample and methodology of measurements. The sample was fabricated as two-dimensional finite structure of hexagonally arranged voids on the PDMS substrate. The applied fabrication protocol was cost-effective and not time-consuming. The final product was a PDMS replica of monolayer colloidal crystal obtained by self-assembly of polystyrene colloidal spheres. Further investigations involved diffractive properties of its periodic structure. Its strain sensitivity was investigated by monitoring the parameters of diffracted (transmitted or reflected) light such as the diffracted wavelength (chapter 6) and the polarization (chapters 7 and 8), which vary by stretching the sample. Moreover, there was tested another approach, which involved shape changes in diffraction pattern. The diffraction pattern is a result of interaction between a periodic structure and an illuminating light. The obtained data confirmed strong relationship between optical response and the geometry of diffractive structure. However, the experiments require further optimization of fabrication protocol, methodology (conditions of measurements, sample parameters, an appropriate arrangement of components in the experimental setups)

The deposition of waste in a landfill can be a threat to the environment and human health; in spite of their potential pollution, landfill are still of grate use for the residual municipal solid waste, thus efficient and cost effective technologies need to be studied in order to minimize aqueous and gaseous emissions. The present work focuses on the evaluation of the remediation of old landfill sites that pollutes groundwater and on the determination of a new pre-treatment of fresh waste upstream of landfilling. First the biosparging technology has been applied to remediate an aquifer polluted by leachate. The biosparging stimulates the growth of indigenous bacteria able to convert pollutants, such as ammonium nitrogen, in harmless compounds. The technology shows high efficiency in ammonium nitrogen removal via nitrification processes. The biosparging remediation technology prevents the mobilization of metals and removes the nitrates produced in the nitrification process when the organic carbon source is conveniently dosed. The application of the biosparging on site has proven to be feasible. The Solidification/Stabilization (S/S) technology is a pre-landfill waste treatment process, which has been used for different types of hazardous wastes since it has a proved efficiency on heavy metal immobilization. The S/S process uses chemically reactive formulations that, together with the water, form stable solids; it also insolubilizes, immobilizes, encapsulates, destroys, sorbs, or otherwise interacts with selected waste components. The S/S process improves the physical characteristics of the waste and reduces the mobility of the hazardous compounds, thus the waste leaches less contaminants into the environment. The result of this process is a less hazardous solid. The experimental evidences proved that this technology reduces volumes used for landfilling and inhibits the methanogenesis blocking greenhouse gases emissions. The reduced permeability and the leaching test results show that the leachate produced is of a smaller amount and less polluted. The enhanced mechanical properties and the reduced emissions both in bodies of water and atmosphere have proven the worth of this technology. Therefore an alternative waste treatment plant involving S/S pre-treatment is proposed.

Over the last two decades, the production of excess sludge has increased rapidly due to a more stringent legislation on effluent quality and a growing number of new plants, becoming an economic and an environmental critical issue. Processing excess sludge could account for half up to 65% of the total operation costs of a wastewater treatment plant. Technologies to reduce the excess sludge had been widely studied. Several studies reported that the technologies integrated in the wastewater handling units should be cost effective and preferable rather than the techniques integrated in the sludge handling units, as they allow to reduce the sludge production rather than treat it. Thus, the development and the optimization of a technology able to reduce the sludge production in the water line is now challenging. A lot of technique have been developed such as biological, thermal, high temperature oxidation, mechanical treatments, ultrasonication, ozonation or by using chemical compounds. Some of these have been proven not energy saving, while others can negatively affect the effluent quality of the process due to the formation of by-products. Among others, biological treatments are a challenging strategy for sludge reduction. In recent years, several studies showed that including an anaerobic bioreactor in the returned activated sludge line of a conventional activated process could significantly enhance the sludge reduction without causing negative effects on operational performances. Today, this configuration is known as anaerobic side-stream reactor (ASSR) process. Several laboratory applications highlighted that the sludge yield of the ASSR process could be reduced up to 60% compared to a conventional activated process. Despite the highest percentage of sludge reduction achieved, the process is still little applied to real scale because its main operating parameters and sludge reduction mechanisms are still unclear. This study focused on the verification of ASSR process, the mechanisms of sludge reduction and the microbial structure of the process. During the first part of the research, a laboratory experimental system was designed and implemented. A sequencing batch reactor (SBR), to simulate the water line of a real wastewater treatment plant, and an ASSR as a sludge treatment unit composed the system. Unlike most of the previous studies, the system was fed with real urban wastewater in order to obtain results that reflect as much as possible what can really happen to a municipal WWTP. Through a critical analysis of the literature, the influence of two important operating parameters, such as the solid retention time (SRT) of the ASSR and the interchange rate (IR), which means the percentage of biomass cycled into the ASSR, had been uncovered Given this, the experimental system was started up and reached a stable condition after 60 days. The research was developed in three different phases that lasted for about 90 days each. The experimental lab system was tested under three configurations: i) 10% sludge interchange rate and SRT in the ASSR of 10 days; ii) 20% sludge interchange rate and SRT in the ASSR of 5 days and iii) 40% sludge interchange rate and SRT in the ASSR of 2.5 days. The observed sludge yield (Yobs) of each phase was evaluated and was equal 0.21 g TSS/g COD, 0.14 g TSS/g COD and 0.12 g TSS/g COD in Phase I, II and III, respectively. These results confirmed that the process could significantly decrease the sludge production and a reduction up to 62% could be achieved. To explain the results obtained in terms of sludge reduction, different tests and analysis were performed. The release of soluble COD and ammonia in the ASSR have highlighted that the endogenous decay and cell lysis mechanism occur in the ASSR. Extraction of EPS, with CER and BASE methods, showed a release of protein and polysaccharides in the bulk solution that increased passing between Phase I and III. At the end of each experimental phase, batch tests were carried out to evaluate the activity of phosphorus accumulating organisms (PAO) and denitrifying phosphorus accumulating organisms (DPAO). Recirculation in SBR-ASSR selects DPAO microorganisms. This was a result of great interest because DPAO could enhance the biological nutrient removal since nitrogen and phosphorus can be simultaneously removed. Furthermore, DPAO has lower cell yield than PAO resulting in lower sludge production. Results showed an activity of PAO, DPAO and other slow growers such as sulfate reducing bacteria. All these results suggested that the high percentage of sludge reduction could be explained as a combination of aspects, such as the cell lysis, the cryptic growth, the selection of slowing microorganisms and EPS destructuration. The SRT and the IR could be considered as main parameters and their variation could significantly affect the performance of the process. Microbial analyses were carried out to investigate the bacterial and archaeal structure of the ASSR sludge during each phase.The results confirmed the presence of several bacteria that are typically heterotrophic responsible of hydrolysis and fermentative process of organic matter. Several slow growers bacteria were also detected. Moreover, according to the batch tests on PAO and DPAO activity, a relevant increase in Phase III of some genera able to enhance the biological phosphorous removal has been observed. In summary, the research found that the ASSR process is a sustainable solution for the sewage sludge reduction due to an efficient and a low sludge production, able to ensure both carbon, nutrients and phosphorous removal applying an extremely simple technology, easy to realize both in new and in existing wastewater treatment plants.

Air pollution is still the cause of several diseases, among which cancer is often associated to excessive or anomalous exposure to air pollutants. In addition to well-known sources of emission of air pollutants, several activities are still unregulated or not adequately controlled by conventional removal technologies; furthermore, the presence of local criticalities may elude the conventional monitoring approach. This thesis aims at providing new options to detect anomalous situations of exposure and to minimize the impacts of air pollutants by acting on two different levels: the prevention of excessive intakes and the prevention of emissions into the atmosphere. Carcinogenic organic air pollutants will receive special attention in this thesis. After a short introduction to the topic, in the second chapter of this thesis, potential critical situations of exposure are presented, with a special focus on two of the most potent carcinogenic air pollutants: dioxin and benzene. Open issues regarding both the lack of regulations for some activities and the inadequacy of some conventional monitoring approaches are described. Proposals for integrative monitoring techniques and methodologies for exposure assessment are then briefly presented. Four of them were developed during this doctoral research and are described in more details in the third chapter of this thesis; the purpose of these methodologies is to offer additional tools to detect anomalous situations of exposure to air pollutants, in both rural and urban contexts, and to estimate the dominant source of exposure to specific compounds in an area. The fourth chapter is dedicated to presenting a proposal for a limit value of dioxin deposition to soil. Dioxin are able to accumulate in the food chain; therefore, this chapter presents the development of a reverse food-chain model, starting from the Tolerable Daily Intake proposed by the World Health Organization, running through the food chain backwards on the basis of the diet of a population and determining a safe value to preserve fields and pastures. Such method represents an attempt to overcome the current absence of a regulatory limit value for atmospheric deposition of dioxin to soil. This approach aims at reducing the potential exposure to dioxin by preventing excessive intake. In the fifth chapter, a critical analysis on biofilters is carried out. Biofilters are a specific kind of air pollution control technology, widely used to treat air streams with low concentrations of volatile organic compounds (VOCs). Biofilters may be inefficient under unsteady conditions of inlet loading rate; in addition, when treating high flow rates, biofilters cannot guarantee a proper dilution of the plume in the atmosphere, due to intrinsic design reasons. Biotrickling filters (BTFs) are here presented in a review as a more efficient alternative; the improvements in air quality obtained when replacing a biofilter with BTFs are also highlighted through dispersion simulations. This chapter aims at proposing an alternative to reduce exposure directly at the emission level, rather than at the receptor level. The same aim is pursued in the final part of this thesis, in which an innovative VOC removal technology is studied: non-thermal plasma (NTP). Two laboratory activities are presented: initially, NTP is applied to treat two mixtures of air and VOCs, chosen to represent typical emissions from real industrial activities; the positive results in terms of VOC removal and the partial formation of more soluble byproducts led to a second exper-imental activity in which NTP was applied as a pre-treatment to a biofilter. NTP revealed to be a promising option to manage peaks of inlet loading rate, which biofilters are often subject to in real cases.