Real-time monitoring of microbial induced corrosion processes in soil and water

Microbial induced corrosion (MIC) is a critical concern for the integrity and longevity of both underground and submerged structures, as well as for facilities involved in the transportation of microbiologically rich fuids. Proper monitoring of microbial-related processes is essential for predicting and mitigating the onset of MIC. This thesis highlights and emphasizes the signifcance of accurate and timely monitoring of these processes in order to prevent possible detrimental effects. A novel setup for the targeted detection of microbial activity in soil is proposed and validated, specifically in a clayey matrix. The innovative sensor configuration, which functions as a galvanic sensor for microbial cathodic activity, is compared with common electrochemical soil parameters including conductivity, redox potential and free corrosion potential. This setup has demonstrated the capability to independently identify the onset of microbial corrosion without the need for additional parameter monitoring. Furthermore, a second sensor, designed as a spectroelectrochemical flow cell, is introduced for realtime laboratory-scale monitoring of microbial corrosion processes. This advanced sensor configuration allows for multiple simultaneous measurements, including biofilm galvanic probe metrics, redox potential, conductivity and diffused reflectance spectroscopy. Both sensor systems are validated through corrosion assessments based on polarization resistance measurements and effective biofilm formation via diffused reflectance measurements (when applicable). As a further sensing application in the area of electrochemical process control, the proposed flow cell is also adapted for concentration measurements of dissolved ozone in water and real time monitoring of produced ozone via electrochemical ozone generation process on doped tin oxide electrode.

La corrosione microbiologica è un fenomeno di particolare importanza per l'integrità e la longevità delle strutture metalliche interrate e sommerse, così come per gli impianti che trattano fluidi microbiologicamente ricchi. Un corretto monitoraggio dei processi legati all'attività microbiologica sui metalli è fondamentale per predire e mitigare l'evento di corrosione microbiologica. In questo lavoro viene proposto un setup innovativo per l'identificazione dei processi di corrosione microbiologica nel suolo attraverso la misurazione di un singolo parametro. Il sensore proposto funge da sonda galvanica di biofilm. Inoltre viene introdotto un setup da laboratorio per il monitoraggio multifisico dei processi di corrosione microbiologica in acqua, basato sulla misurazione della resistenza di polarizzazione, potenziale redox, potenziale biox e riflettanza della superficie. Lo stesso setup è poi impiegato nella misurazione ottica real-time della concentrazione di ozono in elettrolita limpido.