Reactivation and Performance of Stored Aerobic Granules for the in Industrial Wastewater Treatment

Stored aerobic granules, if recovered adequately without a substantial loss of structural integrity and biological function, offer a viable option for long-term storage in practical applications. This study used aerobic granules stored for 30 days in tap water. To assess the stability of the stored granules and the effectiveness of their removal of organic pollutants following reactivation, the reactor was run for 50 days. Industrial wastewater with an organic loading rate (OLR) of 3.4 g of COD/L·day was fed into the reactor. The findings showed that after 10 days, the stored granules quickly reactivated, removing total COD, soluble COD, NH4+-N, TN, and TP with removal efficiencies of 94%, 83%, 97%, 88%, and 85%, respectively. More than 90% granulation percentages and SVI15 levels below 40 mL/g indicated the exceptional settleability of the reactivated granules’ exceptional settleability. These results showed that storing aerobic granules in tap water could enable rapid startup of granular sludge reactors. However, to determine the shelf life of stored granules and the survival of key strains responsible for eliminating organic pollutants from industrial wastewater, further investigation is needed.