From waste to bioplastics: A comprehensive data-driven review on polyhydroxyalkanoates production and recovery from aerobic granular sludge wastewater systems

Aerobic granular sludge (AGS) wastewater treatment biotechnology offers several advantages over the conventional activated sludge process, providing a promising platform for recovering polyhydroxyalkanoates (PHA), a high-value biopolymer. This study used statistical analyses of published data to identify key operational parameters influencing PHA production in AGS systems. Spearman's correlation analysis (p 1 mm) significantly improved PHA accumulation. In contrast, influent COD, aeration time, organic loading rate (OLR), and volumetric exchange ratio (VER) exhibited weak or insignificant correlations. Principal component analysis (PCA) indicated that influent COD, aeration time, and granule size were the primary variables associated with PHA accumulation. Classification and Regression Tree (CART) analysis identified aeration time as the most influential parameter and VER as the least. Granule size, influent COD, and feeding time each had relative importance values exceeding 50% compared with aeration time. Regression modelling identified optimal conditions for maximizing PHA content: influent COD of 4500 mg/L, feeding time of 60 min, aeration time of 359 min, granule size of 2.64 mm, and an OLR of 3.64 kg COD/m 3 ·d; valid within the dataset values used in the current study. Despite the strong potential of AGS for PHA recovery, large-scale adoption remains constrained by technical and economic challenges, emphasizing the need for further research on process optimization and scale-up. • AGS is a robust platform supporting intracellular PHA production and accumulation. • Short feeds (10-20 min) and >1 mm granules boost PHA accumulation in AGS systems. • PCA showed COD, aeration time and granule size to be main factors in PHA enrichment. • CART identified aeration time as the top factor driving PHA production in AGS. • PHA recovery from AGS requires optimization before feasible large-scale production.