Reactivation and efficiency of aerobic granules for wastewater treatment under various storage conditions: a review

Abstract

In 2024, The U.S. Environmental Protection Agency revealed strategic guidelines to develop resilient drinking water and wastewater systems for providing safe water supply and sanitation services. The treatment of wastewater is mandatory, and emerging treatment technologies are expected to achieve near-zero wastewater discharge using sustainable methodologies. A biological wastewater treatment using the aerobic granular sludge (AGS) process promises to employ microorganisms for effective degradation of pollutants. The storage and subsequent reactivation of these granules remains a critical challenge that affects their long-term viability and operational efficiency. The effects of temperature, storage duration and storage methods on the pollutant removal efficiency of AGS is evaluated based on results from this review. Storage induced challenges are detailed in the granule, with evidence-based strategies to improve granule reactivation and performance. These factors have to be understood in order to optimize AGS applications in wastewater treatment. In addition, this review provides a comprehensive understanding of storage-induced challenges and proposes evidence-based recommendations for maintaining granule efficiency after storage.