Politecnio die Bari - Catalogo di prodotti della Ricerca
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A review on cognitive workload for industry 5.0
No full textIn the evolving landscape of Industry 5.0 (I5.0), where digital technologies are increasingly integrated into indus-
trial processes, understanding cognitive workload (CWL) during maintenance tasks has become critical. CWL sig-
nificantly influences an operator’s performance, safety, and overall well-being, especially in complex and de-
manding environments. The introduction of cognitive and assistive technologies, such as augmented reality (AR),
virtual reality (VR), and artificial intelligence, holds the potential for reducing cognitive strain. However, exist-
ing research largely focuses on post-hoc CWL assessment rather than on integrating CWL considerations into the
design phase of maintenance systems, according to an I5.0 perspective. Additionally, methodologies for accu-
rately measuring and modelling CWL in real-time remain underdeveloped. In this context, assessing the opera-
tor’s CWL can be a key factor in evaluating design and management alternatives for industrial systems, aiming to
ensure the operator’s well-being. Reducing CWL should, therefore, be a criterion for evaluating maintenance sys-
tems, including task execution methods and how support information is presented.
This study addresses these gaps by investigating, through a systematic literature review, the existing methods
to evaluate operators’ CWL and explores how they can be integrated into managing maintenance operations in
the I5.0 context, with a specific focus on scenarios where digital technologies provide support. The identified
CWL assessment approaches were categorised into three primary areas: CWL as a factor influencing the opera-
tor’s performance, CWL as a measure for assessing the effectiveness of solutions, and CWL as a design driver. The
findings reveal that AR and VR applications are widely adopted for supporting maintenance activities, but there
are no clear results on their potential to reduce the operator’s CWL. Moreover, results indicate that practical
methodologies for real-time CWL monitoring and predictive modelling are lacking. We highlight the need for ro-
bust models to minimize CWL based on task and environmental factors, aligning with I5.0′s emphasis on human-
centred design.
The study contributes to the body of knowledge by identifying key research gaps and proposing a structured
framework for CWL assessment in industrial systems development. It emphasizes the development of integrative
methodologies for CWL assessment that are based on both subjective and physiological measurements. It more-
over offers practical insights for designing maintenance systems that prioritize operator cognitive well-being
alongside performance efficiency
Costruire dall’interno della preesistenza. Declinazioni del rapporto tra scatola muraria e copertura nell’architettura di Danilo Guerri
No full textIl lavoro di ricerca indaga l’opera dell’architetto marchigiano Danilo Guerri (1939-2016), individuando come principale nucleo teorico-interpretativo il rapporto tra dato costruttivo, forma architettonica e qualità dello spazio messo a punto in occasione di interventi di trasformazione di edifici esistenti.
Stabiliti i margini di questo preciso taglio critico – a cui la veste di architetto-costruttore, come Guerri stesso si definisce, è naturalmente incline – la trattazione approfondisce le ragioni di tale approccio ripercorrendo gli anni della formazione romana e delle prime esperienze professionali, così come la definizione di un bagaglio culturale di riferimento e l’avvio di una nuova stagione lavorativa (sia professionale che accademica) segnata dal ritorno nelle Marche. La ricostruzione di questo scenario offre l’opportunità di intraprendere una lettura trasversale dell’opera di Guerri e di codificarne i caratteri architettonici e costruttivi più emblematici.
A seguito dell’inquadramento dei capisaldi teorici e progettuali entro cui l’autore si muove, il campo di indagine si restringe a tre casi studio paradigmatici: casa Guerri a Falconara Alta (1975-1977), la Cassa Rurale e Artigiana di Castelferretti (1977-1982) e casa Salina a Civitanova Marche (1997-2005). Seppur attraverso strategie di intervento differenti, queste architetture sono accomunate dalla volontà di riprogettare la preesistenza dall’interno; lo spazio interno dei fabbricati già costruiti viene completamente smantellato e ripensato, mentre l’involucro murario è preservato e consolidato o – là dove le esigenze strutturali ne impongono la demolizione – opportunamente ricostruito.
La salvaguardia della facies antica restituisce un manufatto coerente con la realtà che lo ospita, custodendone e valorizzandone la memoria storica, mentre le nuove spazialità di progetto vedono l’affermazione di una concezione strutturale più dichiaratamente moderna, spesso legata anche ad una reinterpretazione delle forme, dei materiali e delle tecniche della tradizione. Il processo di trasformazione dell’invaso spaziale, inoltre, individua nella forma costruttiva della copertura (sia essa conclusiva o intermedia) un dispositivo di caratterizzazione e di gerarchizzazione interna. In quest’ottica, l’approfondimento analitico dei tre progetti considerati – coadiuvato dalla messa a punto di ridisegni critici ed analisi grafiche – indaga la relazione intrinseca tra scatola muraria, copertura e spazio costruito.
In conclusione, la trattazione propone delle considerazioni che – astraendosi dalla specificità del tema scelto – conducono ad una riflessione di carattere generale applicabile al rapporto tra preesistenza e progetto di architettura, desumendo dal lavoro di Guerri dei paradigmi di metodo atemporali in grado di coniugare, nell’approccio al recupero e al riuso del patrimonio costruito, istanze conservative e trasformative.The research investigates the work of Marche native architect Danilo Guerri (1939-2016), identifying as its main theoretical-interpretative nucleus the relationship between constructive datum, architectural form and quality of space developed during the transformation of existing buildings.
Having established the margins of this precise critical slant - to which the role of architect-constructor, as Guerri defines himself, is naturally inclined - the dissertation delves into the reasons for this approach by retracing the years of his education in Rome and his first professional experiences, as well as the definition of a cultural background and the start of a new working season (both professional and academic) marked by his return to the Marche region. The reconstruction of this scenario offers the opportunity to undertake a transversal reading of Guerri’s work and to codify its most emblematic architectural and constructive features.
Following the framing of the theoretical and design cornerstones within which the author moves, the field of investigation narrows down to three paradigmatic case studies: Casa Guerri in Falconara Alta (1975-1977), the Cassa Rurale e Artigiana in Castelferretti (1977-1982) and Casa Salina in Civitanova Marche (1997-2005). Although through different intervention strategies, these architectures are united by the desire to redesign the pre-existence from the inside; the interior space of the already constructed buildings is completely dismantled and rethought, while the masonry envelope is preserved and consolidated or - where structural needs dictate its demolition - suitably reconstructed.
The preservation of the ancient facies returns an artefact that is coherent with the reality that hosts it, preserving and enhancing its historical memory, while the new project spaces see the affirmation of a more avowedly modern structural conception, which is often linked to a reinterpretation of traditional forms, materials and techniques. The transformation process of the enclosed space, moreover, identifies in the constructive form of the roof (whether conclusive or intermediate) a device of internal characterisation and hierarchisation. From this point of view, the analytical study of the three considered projects - assisted by the development of critical redrawings and graphic analyses - investigates the intrinsic relationship between masonry box, roof and built space.
In conclusion, the dissertation proposes some thoughts that - abstracting themselves from the specificity of the chosen theme - lead to a general consideration applicable to the relationship between pre-existence and architectural design, deducing from Guerri’s work some paradigms of an atemporal method capable of combining conservative and transformative instances in the approach to the recovery and reuse of built heritage
User-centric urban energy modelling: A reduced order model approach based on pre-calibrated archetypes dataset
No full textSignificant efforts have been directed by governments and international organizations towards establishing sustainable development programs for cities and communities to facilitate the urban energy transition, encountering challenges in evolving towards a cleaner and more resilient energy system. In support of designing and operating such sustainable energy systems, the development of appropriate modelling frameworks becomes crucial. These frameworks should enable the identification of renovation priorities and the formulation of innovative energy management schemes, business models, and insights for self-sustaining urban districts or communities. The core of implementing sustainable energy hubs in an urban context is undergoing as well as modelling the end-users’ energy demand and their interaction with the hub. This study presents a modelling approach to unlock some of the main challenges encountered in urban energy demand simulation with a perspective to user-centric modelling framework. Specifically, a urban energy demand modelling framework integrating building Reduced Order Models with end-user occupancy dynamics to provide a scalable and comprehensive solution is developed. The method leverages archetype end-user categories derived from detailed white-box building simulations and Time-of-Use Survey data, creating a framework for generating Resistance-Capacitance-based datasets applicable to urban-scale simulations. By capturing complex heat transfer dynamics, the approach facilitates scalability from individual buildings to large clusters. The approach is tested through a proof-of-concept simulation, and it is considered a valid tool to conduct multi-domain analysis and to support the development of building clusters and community energy renovation
Greenhouse Gases Detection Exploiting a Multi-Wavelength Interband Cascade Laser Source in a Quartz-Enhanced Photoacoustic Sensor
No full textThis study presents the performance of a multi-gas sensor for greenhouse detection based on quartz-enhanced photoacoustic spectroscopy (QEPAS). The QEPAS sensor exploits an innovative, compact three-wavelength laser module as excitation source. The module integrates three interband cascade laser chips with a beam combining system, all enclosed in a compact metallic package with sizes of 40 × 52 × 17 mm to generate a single output beam. The multi-gas QEPAS sensor was tested in a laboratory environment for the sequential detection of two greenhouse gases, methane (CH4) and carbon dioxide (CO2), and a precursor greenhouse gas, carbon monoxide (CO). At an integration time of 100 ms, minimum detection limits of 21 ppb, 363 ppb, and 156 ppb, were estimated for CH4, CO2, and CO detection, respectively, all well below their natural abundance in air
Multiparametric Study of Water–Gas Shift and Hydrogen Separation Performance in Membrane Reactors Fed with Biomass-Derived Syngas
Get PDFA multiparametric study was conducted on a hydrogen (H2) production rig designed to process 0.25 nm3·h−1 of syngas. The rig consists of two Pd-Ag membrane permeator units and two Pd-Ag membrane reactor units for the water-gas shift (WGS) reaction, enabling a detailed and comprehensive analysis of its performance. The aim was to find the optimal conditions to maximise hydrogen production by WGS and its separation in a pure stream by varying temperature, pressure, and steam-to-CO ratio (S/CO). Two syngas mixtures obtained from an updraft gasifier using different gasification agents (air-steam and oxy-steam) were used to investigate the effect of gas composition. The performance of the rig were investigated at nine combinations of temperature, pressure, and S/CO in the respective ranges of 300 - 350 °C; 2 - 8 bar; 1.1- 2 mol·mol−1 as planned with the help of a design of experiment (DOE) software. The three parameters positively effected the performances, both as capacity of separating a pure stream of H2 reported as moles permeated per unit of surface area and time, and producing new H2 from WGS, reported as moles of H2 produced per volume of catalyst unit and time. The highest yields were obtained using syngas from oxy-steam gasification, which had the highest H2 concentration and was free of N2
Un nuovo approccio teorico e sperimentale allo studio della meccanica dell'impatto nella dinamica del rocking di strutture in muratura
No full textLa salvaguardia e la tutela delle costruzioni storiche in muratura in aree sismicamente attive rappresenta una delle sfide più complesse e rilevanti nel campo dell'Ingegneria e dell'Architettura. Il nostro patrimonio architettonico e archeologico presenta vulnerabilità specifiche che lo rendono fortemente suscettibile ai danni provocati dai terremoti. Per cui, risulta necessario procedere allo sviluppo di appropriati approcci teorici allo studio del comportamento dinamico di queste strutture che consentano di prevenire le più diffuse modalità di collasso e di progettare sapienti interventi per la conservazione e la salvaguardia dell'edificato storico-monumentale. L'approccio prevalentemente impiegato per lo studio della dinamica delle costruzioni in muratura costituite da blocchi si basa sugli studi di Housner (1963), ovvero sulla dinamica del "rocking" di strutture costituite da blocchi rigidi. Questo approccio teorico è impiegato sia per lo studio di elementi strutturali costituiti da blocchi sovrapposti, come per esempio le colonne dei templi, sia per lo studio delle strutture curve (archi e volte), elementi strutturali molto diffusi nel patrimonio storico e architettonico anche definito "minore" come quello dei centri storici del Mediterraneo.
La presente tesi di dottorato si inserisce in questo ambito di ricerca formulando un nuovo approccio teorico e sperimentale alla caratterizzazione della meccanica dell'impatto nella dinamica di strutture in muratura.
Uno degli obiettivi conseguiti è stato quello di comprendere l'influenza che il danneggiamento conseguito agli spigoli dei blocchi durante l'oscillazione (rocking) possa comportare sul comportamento dinamico complessivo della struttura nonché sulla sua stabilità. In particolare, le rotture degli spigoli alterano la geometria del blocco, generando un comportamento dinamico che può divergere significativamente da quello di un blocco integro ossia con spigoli non danneggiati.
Per cui è stato, in primis, sviluppato un nuovo modello analitico introducendo una geometria raccordata per i bordi danneggiati dei blocchi rigidi descritta da nuovi parametri geometrici, tra cui l'angolo \psi, che permette di rappresentare in modo più accurato la transizione tra la fase di rotolamento e la fase di oscillazione pura dei sistemi mutiblocco. Questo approccio ha consentito di analizzare con maggior dettaglio le variazioni della stabilità del blocco e la sua dissipazione energetica durante il moto oscillatorio.
Un ulteriore importante obiettivo conseguito è stato quello di comprendere e superare le limitazioni del modello classico del rocking (modello di Housner) anche sulla base delle evidenze sperimentali, formulando un nuovo approccio teorico che considerasse blocchi rigidi ma localmente deformabili all'interfaccia.
Mediante modelli numerici sviluppati in ambiente MATLAB sono stati confrontati i due approcci teorici formulati con quello classico presente in Letteratura, considerando diversi scenari di input sismico. Le simulazioni numeriche hanno adottato una rappresentazione "puntuale" dell'impatto, che tenga conto delle proprietà meccaniche dei materiali dei blocchi e del Coefficiente di Restituzione (CoR), parametro cruciale per descrivere la dissipazione di energia durante gli impatti.
I modelli teorici formulati hanno consentito di studiare in modo efficace la risposta dinamica del blocco, garantendo un'accurata valutazione dell'influenza che la geometria del blocco e le proprietà del materiale possono avere nella meccanica dell'impatto. Al contempo, l'approccio sviluppato costituisce un utile riferimento per sviluppare modelli che possano anche considerare una distribuzione continua delle forze all'interfaccia del blocco.
A supporto dei modelli analitici proposti e delle simulazioni numeriche, sono state condotte prove sperimentali su provini realizzati in scala ridotta, sia con spigoli non raccordati (retti) sia con spigoli raccordati, sottoposti a sollecitazioni dinamiche indotte da un attuatore dinamico. Questi blocchi sono stati testati su superfici di materiali differenti, una scelta motivata dalla necessità di indagare la dipendenza della risposta dinamica dalle proprietà meccaniche dei materiali, contrariamente a quanto avviene nel modello classico di Housner, che considera esclusivamente parametri geometrici. Le prove sperimentali hanno fornito dati fondamentali per validare il modello analitico proposto, permettendo di studiare in dettaglio gli effetti delle imperfezioni strutturali, delle condizioni di contatto e dei meccanismi di dissipazione dell'energia.
I risultati ottenuti hanno dimostrato l'importanza di una rappresentazione accurata della geometria del blocco e delle proprietà meccaniche dei materiali coinvolti nell'impatto, nonché l'influenza di questi fattori sulla risposta dinamica del sistema. Le analisi teoriche, le simulazioni numeriche e i risultati sperimentali hanno permesso di studiare in maniera completa il fenomeno del rocking delle strutture multiblocco in muratura, un fenomeno ancora da studiare soprattutto con riferimento alle strutture curve. L'approccio teorico sviluppato si presume possa essere esteso anche ai sistemi multiblocco caratterizzati da geometriche articolate come gli archi.
Si conclude che l'approccio teorico e sperimentale proposto ha avuto l'obiettivo di studiare alcuni aspetti della dinamica del rocking che in Letteratura sono stati parzialmente affrontati: (a) il comportamento dinamico dei blocchi in muratura danneggiati durante l'oscillazione (da cui la scelta di considerare blocchi con spigoli raccordati); (b) l'influenza che le proprietà meccaniche dei blocchi possano avere sul comportamento dinamico complessivo dell'elemento strutturale. In particolare, si sottolinea che quest'ultimo aspetto non sia stato ancora dovutamente studiato in quanto i modelli proposti in Letteratura fanno riferimento al classico approccio di Housner che si basa sull'ipotesi di rigidità dei blocchi. Per cui, lo studio della dinamica del rocking attualmente si basa su considerazioni puramente geometriche senza tener conto della possibile deformabilità dei blocchi all'impatto che può anche completamente cambiare il comportamento dinamico complessivo della struttura come spesso si è osservato nelle strutture reali.
I risultati ottenuti in questa tesi vogliono evidenziare come una modellazione teorica che tenga conto degli effetti dissipativi dovuti anche alla deformabilità dei blocchi possa cogliere meglio gli aspetti del rocking osservati sperimentalmente e alcune fenomenologie osservate nei casi reali e non ancora chiarite teoricamente.
Una comprensione più accurata della dinamica del rocking delle costruzioni in muratura è necessaria per un progetto sapiente ed efficace degli interventi di tutela e di conservazione dei manufatti archeologici e architettonici, al fine della salvaguardia del nostro notevole patrimonio storico.The protection and preservation of historic masonry buildings in seismically active areas represent one of the most complex and significant challenges in the fields of Engineering and Architecture. Our architectural and archaeological heritage presents specific vulnerabilities that make it highly susceptible to earthquake-induced damage. Therefore, it is necessary to develop appropriate theoretical approaches to study the dynamic behavior of these structures, which allow us to prevent the most common modes of collapse and to design prudent interventions for the conservation and safeguarding of historic monumental buildings.
The approach predominantly used for studying the dynamics of masonry constructions composed of blocks is based on the studies of Housner (1963), that is, on the rocking dynamics of structures composed of rigid blocks. This theoretical approach is employed both for the study of structural elements made of superimposed blocks, such as temple columns, and for the study of curved structures (arches and vaults), structural elements widely present in the historical and architectural heritage—including the so-called "minor" heritage found in the historic centers of the Mediterranean.
This doctoral thesis fits into this field of research by formulating a new theoretical and experimental approach to characterize the mechanics of impact in the dynamics of masonry structures.
One of the objectives achieved was to understand the influence that damage incurred at the edges of the blocks during oscillation (rocking) can have on the overall dynamic behavior of the structure as well as on its stability. In particular, the breaking of the edges alters the geometry of the block, generating a dynamic behavior that can significantly diverge from that of an intact block with undamaged edges.
Therefore, first and foremost, a new analytical model was developed by introducing a rounded geometry for the damaged edges of the rigid blocks, described by new geometric parameters, including the angle \psi, which allows for a more accurate representation of the transition between the rolling phase and the pure oscillation phase of multiblock systems. This approach made it possible to analyze in greater detail the variations in the block's stability and its energy dissipation during rocking motion.
A further important objective achieved was to understand and overcome the limitations of the classical rocking model (Housner's model), also based on experimental evidence, by formulating a new theoretical approach that considers rigid blocks but locally deformable at the interface. Using numerical models developed in the MATLAB environment, the two formulated theoretical approaches were compared with the classical one present in the literature, considering different seismic input scenarios. The numerical simulations adopted a "point-like" representation of the impact, taking into account the mechanical properties of the block materials and the Coefficient of Restitution (CoR), a crucial parameter for describing energy dissipation during impacts.
The formulated theoretical models allowed for an effective study of the block's dynamic response, ensuring an accurate assessment of the influence that the block's geometry and material properties can have on the mechanics of the impact. At the same time, the developed approach serves as a useful reference for developing models that can also consider a continuous distribution of forces at the block's interface.
To support the proposed analytical models and numerical simulations, experimental tests were conducted on reduced-scale specimens, both with non-rounded (straight) edges and with rounded edges, subjected to dynamic stresses induced by a dynamic actuator. These blocks were tested on surfaces of different materials, a choice motivated by the need to investigate the dependence of the dynamic response on the mechanical properties of the materials—contrary to what occurs in the classical Housner model, which considers exclusively geometric parameters. The experimental tests provided fundamental data to validate the proposed analytical model, allowing for a detailed study of the effects of structural imperfections, contact conditions, and energy dissipation mechanisms.
The results obtained demonstrated the importance of an accurate representation of the block's geometry and the mechanical properties of the materials involved in the impact, as well as the influence of these factors on the system's dynamic response. The theoretical analyses, numerical simulations, and experimental results allowed for a comprehensive study of the rocking phenomenon of multiblock masonry structures—a phenomenon still to be explored, especially concerning curved structures. The developed theoretical approach is presumed to be extendable to multiblock systems characterized by complex geometries such as arches.
In conclusion, the proposed theoretical and experimental approach aimed to study certain aspects of rocking dynamics that have been partially addressed in the literature: (a) the dynamic behavior of masonry blocks damaged during oscillation (hence the choice to consider blocks with rounded edges); (b) the influence that the mechanical properties of the blocks can have on the overall dynamic behavior of the structural element. In particular, it is emphasized that this latter aspect has not yet been duly studied, as models proposed in the literature refer to the classical Housner approach, which is based on the assumption of block rigidity. Therefore, the study of rocking dynamics currently relies on purely geometric considerations without accounting for the possible deformability of the blocks upon impact, which can completely change the overall dynamic behavior of the structure—as has often been observed in real structures.
The results obtained in this thesis aim to highlight how a theoretical modeling that takes into account dissipative effects due to the deformability of the blocks can better capture the aspects of rocking observed experimentally and some phenomena observed in real cases that have not yet been theoretically clarified. A more accurate understanding of the rocking dynamics of masonry constructions is necessary for the wise and effective design of protection and conservation interventions for archaeological and architectural artifacts, in order to safeguard our remarkable historical heritage
Fragility analysis of prestressed concrete girder bridges affected by corrosion under traffic loads
Get PDFItalian and European transportation networks include a considerable number of existing bridges, built since the early ‘60s, characterised by simply supported prestressed-concrete (PC) girders with post-tensioned steel tendons. Corrosion of tendons, which may lead to significant loss of structural capacity, cannot be detected by simple visual inspections and requires advanced and expensive testing by bridge owner companies. Therefore, procedures aimed at risk-informed prioritisation for network-scale assessment are needed, to provide fundamental support for drawing up priority lists to be followed for an optimal allocation of resources to be employed for advanced inspections and possible retrofit. The thesis presents a study on the fragility of existing PC girder bridges considering traffic loads, accounting for corrosion-induced effects. An automated framework is proposed, aiming at the efficient probabilistic structural assessment of the investigated bridge class accounting for 1) the influence of knowledge-based uncertainty related to geometric and mechanical properties and 2) different scenarios including diverse critical corrosion levels and code-compliant traffic load models. A simplified analytical method and a refined finite element method are adopted as structure modelling strategies. To simulate corrosion effects, geometric and mechanical characteristics of prestressing steel tendons are modified by reducing the steel area and stiffness, ductility and strength properties. For analytic calculations, such modifications are integrated into a specific algorithm able to estimate variations in flexural and shear bearing capacity of critical cross-sections. In the thesis, the framework is tested with reference to a dataset of case-study superstructures with different span lengths and numbers of beams. The obtained fragility curves are deeply discussed, focusing on the corrosion effect on structural fragility and highlighting the variation of the corrosion-induced increase in fragility among the selected bridge archetypes. Although the proposed methodology presents some simplifications, it could improve the current practices of risk prioritisation, by supporting transportation authorities in ensuring the safety of the existing bridge stock
Smart Fuzzy Logic Based Agricultural Greenhouse Irrigation System
No full textThe paper outlines the development and implementation of an intelligent irrigation control system utilizing the fuzzy logic. The primary aim of this system is to automate the regulation of the water pumps in greenhouses. The key goal is to optimize the water usage and manage the flow rate during the soil irrigation, particularly through the application of the drip irrigation techniques. The system achieves this target by incorporating the climatic parameters and monitoring the soil moisture levels. The results show that the utilization of the fuzzy logic approach proves effective in controlling the watering duration and in concurrently maintaining the optimal temperature and humidity levels within the greenhouse. This dual functionality highlights the efficacy of the fuzzy logic in enhancing the water conservation and ensuring an optimal microclimate for the greenhouse cultivation
Advanced treatments for PFAS removal from landfill leachate: evaluating biological and ozone based chemical approaches
Get PDFIn the last decades, the rapid industrialization, the population growth and the urbanization led to the increase in waste generation. The practices of reuse, recycling, energy and matter recovery from waste are not sufficient to cope with this rise. Therefore, landfilling still remains a widely used practice. Within landfills, waste undergoes a number of physical, chemical and biological changes and releases micropollutants within the landfill leachate, making this matrix one of the most difficult to treat (Kumar et al., 2023).
Leachate is a complex mixture containing very high concentrations of biodegradable and recalcitrant toxic compounds (Qian et al., 2024). It contains a variety of micropollutants, such as polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), pharmaceuticals, personal care products, pesticides, microplastics (MPs), per- and polyfluoroalkyl substances (PFASs), and many more. Although micropollutants are present in very low concentrations they have significant impacts on the ecosystems, economy, human health.
The subject of this study are per- and polyfluoroalkyl substances, better known as PFAS, substances synthesized since the 1950s and entered the composition of a great many commercial products because of their outstanding hydro-, oleo-repellency and high stability characteristics. PFASare found in a wide range of products, from fertilizers to food packaging, from personal hygiene products to fire-fighting foams. These, at the end of their life cycle, sent to landfills release fluorinated substances into leachate, where the concentrations can reach up to thousands of μg/L (Gallen et al., 2017).
This study stems from the need to identify a solution for PFAS removal in landfill leachate and aims to evaluate the removal efficacy of PFAS and other key chemical parameters of two bench-scale treatment schemes: a biological treatment conducted in a Sequencing Batch Biofilter Granula Reactor (SBBGR) -and an ozone-enhanced biological treatment. Given the matrix complexity and the high chemical stability of PFAS, conventional treatments are inadequate for the removal of fluorinated substances. Hence the need to investigate an integrated approach combining biological degradation with chemical oxidation. Biological treatment was conducted in an SBBGR, an advanced biological treatment system, which is an upflow reactor in which leachate was fed, treated, and extracted sequentially. The plant operated in sequential mode with 8-hour treatment cycles. Each cycle featured a fill, reaction, and discharge phase. The chemical upgrading included an additional phase, the integration of biological degradation with chemical oxidation, performed with ozone at two different doses (4.0 g/L and 5.5 g/L). The discontinuity of the SBBGR system allowed oxidative treatment with ozone to be used in a specific and controlled manner. The ozonation step, following biological treatment, was specific for resistant biological degradation compounds. Ozone, dosed in a controlled manner, allowed for the partial oxidation of recalcitrant substances before returning them back to the biomass action.
The experimentation consisted of four phases: a start-up phase, a second phase with a steady state biological , a third phase in which biological treatment was enhanced with ozone at two different dosages, and a final phase in which reactor worked in biological mode fed with leachate at high PFAS concentration. During the preliminary start-up phase, an appropriate feeding program was used: gradual dilutions with water at decreasing ratios to acclimate the biomass to high salinity values (approximately 23 mS/cm) and to stimulate the growth of the species involved in the process.
The influent and effluent of all treatment schemes were characterized in terms of traditional parameters and PFAS. Per- and polyfluoroalkyl substances were analyzed by a mass spectrometer interfaced with very high-pressure liquid chromatography
