Algal-Bacterial Aerobic Granular Sludge: Applications and Future Prospects

The algal-bacterial aerobic granular sludge (AB-AGS) system, which combines microalgae with aerobic granular sludge, is a sustainable and promising wastewater treatment method. The algae embedded in the aerobic granulation process allow for the algal and bacterial cells in the sludge to interact and form granular flocs, which increases the treatment efficiency and helps separate the treated wastewater from the biomass. Additionally, AB-AGS biomass can be harvested for the extraction of biolipids and alginate-like exopolymers, contributing to resource recovery. This study reviews the applications and resource recovery potential of the AB-AGS system, highlighting its proven effectiveness in treating a range of wastewaters, from low-strength municipal to high-strength leachate. Keyword co-occurrences analysis further revealed pollutant removal, extracellular polymeric substances, the microbial community, and wastewater treatment as research hotspots. Research trends indicated by the keywords with the most recent publication year focused on system application and granulation factors. Additionally, an increasing number of studies regarding AB-AGS for saline and antibiotic-containing wastewater have also been reported. This review also identifies several research gaps and suggests directions for future investigations in this field.