[Storage and Reactivation of Anaerobic Ammonium Oxidation (ANAMMOX) Sludge at Room Temperature]

Slow growth rates limit the widespread application of anaerobic ammonia oxidation (ANAMMOX) reactions, which presents a need for the study of long-term storage and rapid reactivation of ANAMMOX sludge. Under room temperature conditions (14~30℃), this study investigated the effects of storage duration on the residual activity and the activity after reactivation of ANAMMOX sludge without the addition of external substances. The chosen storage durations were 15, 30, 45, 60, 75 and 100 days, respectively. The results show that the residual specific ANAMMOX activities (SAAs) of the stored ANAMMOX sludge were 90.9%, 64.3%, 61.7%, 43.2%, 25.8% and 19.3% of the initial activity (activity before sludge storage) after 15, 30, 45, 60, 75 and 100 days, respectively. Therefore, the residual SAA decreases linearly with an increase in the storage duration of ANAMMOX sludge (R² was 0.978). The SAAs after reactivation with a storage duration of 15, 30, 45, 60 and 75 days were all higher than the initial SAA and reached 103.4%, 129.3%, 124.8%, 111.7% and 116.9% of the initial SAA before its storage, respectively. However, the SAA after reactivation after storage for 100 days was just 98.9% of the initial SAA. In conclusion, after as long as 100 days of storage duration under room temperature, the residual SAA of ANAMMOX sludge decreases to 0.0513 g·(g·d)^-1, and its ANAMMOX activity can still be recovered after 9.5 days of reactivation culture.