Insight into thiosulfate-driven denitrification and anammox process: Bigger aggregates driving better nitrite utilization on ammonium and nitrate contained wastewater

Abstract

Recent studies have paid attention to thiosulfate-driven denitrification and anammox (TDDA) process on treating ammonium and nitrate contained wastewater. However, technical challenges still existed in coupling denitratation and reducing denitritation to obtain efficient nitrite supply for anammox. By successfully operated two anoxic sequencing batch reactors (ASBR) with two different sizes of TDDA aggregates, the reactor R1 with smaller aggregates (0.195 mm) achieved 83.38% ammonium removal efficiency and 85.39% total nitrogen removal efficiency. In comparison, the reactor R2 with bigger aggregates (0.554 mm) achieved higher ammonium removal efficiency (92.02%) and total nitrogen removal efficiency (90.05%). Different aggregates showed a similar anammox activity and denitratation activity but varied in denitritation activity (3.47 mg/(L·h) in R1 compared to 1.42 mg/(L·h) in R2), indicating bigger aggregates supplied nitrite to anammox process more efficiently. Annwoodia was the pivotal microorganism involved in nitrite acquisition that outcompeted anammox bacteria in smaller aggregates. Bigger aggregates with the less relative abundance of Annwoodia established a more harmonious microbial community to support effective nitrogen removal. This study provides a novel insight into nitrite utilization of TDDA system and sheds light on the operation of ASBR-based TDDA processes for biological nitrogen removal.