Accelerating the formation of aerobic granular sludge (AGS): advances, challenges, and future perspectives

• Lengthy startup time is a big limiting factor of Aerobic Granular Sludge (AGS) Technology. • Bioaugmentation using flocculating bacteria and fungi increases granulation speed. • AGS startup is faster and nutrient recovery is enhanced with the help of algal-bacterial synergy, • Natural polymers such as alginate and chitosan improve granule strength as well as EPS generation. In wastewater treatment, AGS technology is a revolutionary breakthrough that overcomes the drawbacks of the conventional Activated Sludge (AS) method. Large geographic footprints, energy-intensive processes, and complicated biomass-water separation are all overcome by AGS systems. AGS use compact, dense microbial granules to effectively remove carbon, nitrogen, and phosphorus in a single reactor. This review explores the benefits, challenges, and operating principles of AGS, with a focus on accelerating granulation through the use of inoculation and polymer additives. Key topics include the granule formation mechanisms, the role of diverse microbial communities and comparison between AS and AGS. AGS technology has several benefits, but it also has drawbacks, including long granulation periods, granule instability, and environmental limitations. By overcoming these obstacles, AGS can become a viable and affordable option to meet the world’s wastewater treatment requirements, opening the door to more significant financial and environmental advantages. Different methods like bioaugmentation, inoculum and polymer additives can be used to get rapid startup of granulation and enhanced stability. Some future directions for future research, innovation and rapid formation in AGS technology is also discussed.