Resource Recovery from Aerobic Granular Sludge: Potential, Methodologies and State of the Art

Aerobic granular sludge (AGS) represents a promising alternative to the conventional activated sludge process for wastewater treatment, owing to its advantages in reducing land area requirements, operational costs, and carbon footprint. With the increasing global implementation of full-scale AGS systems, recent studies have increasingly concentrated on the recovery of valuable resources from waste AGS. AGS is an effective carrier for a variety of valuable substances, including alginate-like exopolymers, polyhydroxyalkanoates, phosphorus, tryptophan, xanthan, curdlan, and cellulose. This study seeks to offer a thorough review of the recovery potential, extraction methodologies and current state of knowledge regarding each of these materials. To improve economic viability, future studies should focus on developing strategies for the sequential recovery of multiple resources from AGS. Furthermore, integrating AGS with other emerging technologies, such as microalgal treatment and a partial nitritation/anammox process, may enhance the reclamation of organic carbon from wastewater.