Carbon recycling from waste: methanol production from mixed waste and biopolymer synthesis from organic streams within a biorefinery framework

This study explores two complementary strategies for waste valorization to support the transition toward a circular economy. The first part focuses on a thermochemical platform for recovering carbon-rich materials from heterogeneous waste through gasification, which converts the organic fraction into valuable products like syngas and methanol. A detailed mathematical model simulates gasification reactions under varying operational conditions, enabling the identification of optimal plant configurations and operating ranges to maximize carbon recovery. A Life Cycle Assessment (LCA) evaluates the environmental performance of the technology, confirming its advantages over conventional waste treatment. Results show significant reductions in greenhouse gas emissions and energy use. The second part investigates the production of polyhydroxyalkanoates (PHAs) through fermentation using mixed microbial cultures, addressing the current lack of effective predictive models for such complex biochemical processes. Laboratory experiments examine the impact of operational parameters—particularly phosphorus availability—on intracellular PHA accumulation. Polymer analyses assess yield, quality, and application potential, highlighting bottlenecks and proposing optimization strategies. The study contributes to integrated waste management solutions that enhance resource recovery and reduce environmental impacts in line with circular economy principles.