Bibliometric analysis of polyhydroxyalkanoates production from organic waste streams using activated sludge as inoculum: research trends, intellectual structure, and future directions

This study presents a bibliometric analysis of the experimental literature on polyhydroxyalkanoate (PHA) production from organic waste streams using waste activated sludge (WAS) as inoculum over the last ten years (2014–2024). A total of 159 experimental articles were compiled through a systematic search in Scopus and Web of Science, followed by performance analysis, co-citation analysis, and bibliometric coupling using VOSviewer software. The results reveal a notable surge in publications in recent years, particularly in 2021, reflecting growing academic and industrial interest in sustainable plastic alternatives. This momentum is linked to environmental concerns, supply chain disruptions, and increased investment in bio-based solutions following the COVID-19 pandemic. Italy and China lead in publication volume, while Portugal, particularly Universidade Nova de Lisboa, stands out institutionally. Despite these advances, industrial participation remains limited, with Veolia Water Technologies as the only company with a consistent academic footprint. Co-citation analysis identified three major clusters shaping the intellectual structure: (i) enrichment strategies and process setup, (ii) feedstock for PHA production by microbial mixed cultures (MMCs), and (iii) PHA production integrated with waste treatment at pilot scale. Bibliographic coupling revealed three emerging research trends: (i) biopolymer modification, (ii) diversification of organic substrates, and (iii) development of eco-friendly extraction methods. By focusing on the transformation of organic waste into bioplastics, this study highlights the relevance of PHA research within the circular economy framework, in which waste streams are revalorized into renewable, biodegradable materials. The findings provide valuable insights for guiding future research and innovation. • A bibliometric analysis of PHA production from waste streams and WAS was conducted. • Europe and China dominate the research field in terms of productivity and impact. • Co-citation analysis identified three clusters shaping the intellectual structure. • Bibliographic coupling revealed three future research directions . • Stronger industry-academia collaboration is needed to scale up PHA production.