Polyhydroxyalkanoate Production by Municipal Wasted Activated Sludge: The Case Study of Marineo (ITALY) Wastewater Treatment Plant

Polyhydroxyalkanoates (PHAs) are biodegradable polymers with promising applications in various industries. The production of PHAs from sewage sludge represents an innovative and sustainable approach to both waste management and biopolymer synthesis. Sewage sludge, a by-product of wastewater treatment, contains a rich organic carbon source, making it an ideal substrate for producing PHA. This microbial synthesis of PHAs from sewage sludge transforms waste into a valuable resource and mitigates the environmental impact of sludge disposal. Additionally, the cost-effectiveness of utilising sewage sludge as a raw material further enhances the economic viability of PHA production. Still, despite the promising developments, the spread of this process needs to be improved by several challenges. The environmental and economic aspects of the process are yet to be proved since the literature has mainly focused on optimising the process at the laboratory scale. In this context, this study presents the preliminary promising results of a PHA production process by sewage sludge. The experiments were carried out at the deviation line built inside the wastewater treatment plant of Marineo, Italy. Direct accumulation was the strategy adopted by controlled pulsate feeding, which was controlled automatically by homemade software. Preliminary results show a consistent PHA production in quantity (22.1 ± 1.5 g PHA/g VSS %) and monomeric composition at low VFA concentration (186.6 ± 13.7 mg COD/L). Future studies will also focus on evaluating direct greenhouse gas emissions in view of assessing the efficiency and environmental impact of the direct PHA accumulation by sewage sludge.