Alessandra Cesaro

This study aimed to explore innovative sorbent materials for the remediation of contaminated marine environments, with a focus on metal removal from seawater. Adsorption tests were carried out to evaluate the performance of single-cell proteins (SCPs), a protein-rich biomass derived from industrial by-products, in comparison with commercial activated carbon (AC). Given the increasing need for sustainable and effective approaches in sediment remediation and water treatment, identifying alternatives to conventional sorbents is of particular relevance. Results showed that SCPs exhibited higher affinity for Cr than for Zn, while multi-metal solutions improved adsorption, suggesting synergistic interactions possibly linked to surface charge effects and ternary complex formation. Importantly, SCPs demonstrated competitive and, in some cases, superior performance compared to AC, highlighting their potential as an innovative and sustainable material. Moreover, when the absorbent materials were combined, SCP and AC mixes outperformed both the individual adsorbents and the expected additive efficiencies, achieving significantly higher removal yields for both metals, particularly at low concentrations. Overall, these findings suggest that SCPs, alone or in combination with AC, represent a promising strategy for the removal of heavy metals from marine systems, offering new opportunities for the treatment of contaminated sediments and seawater.

This study evaluated the feasibility of contextually producing hydrogen, microbial proteins, and polyhydroxybutyrate (PHB) using a mixed culture of purple phototrophic bacteria biomass under photo fermentative conditions. To this end, three consecutive batch tests were conducted to analyze the biomass growth curve and to explore the potential for optimizing the production process. Experimental findings indicated that inoculating reactors with microorganisms from the exponential growth phase reduced the duration of the process. Furthermore, the most effective approach for simultaneous hydrogen production and the valorization of microbial biomass was found when conducting the process during the exponential growth phase of the biomass. At this stage, achieved after 3 days of fermentation, the productivities of hydrogen, PHB, and microbial proteins were measured at 63.63 L/m³ d, 0.049 kg/m³ d, and 0.045 kg/m³ d, respectively. The biomass composition comprised a total intracellular compound percentage of 56%, with 27% representing PHB and 29% representing proteins. Under these conditions, the estimated daily revenue was maximized, amounting to 0.6 $/m³ d.