Effect of Anammox Granular Sludge Type on the CANON Process with Immobilized Fillers Treating Domestic Wastewater

Abstract

Immobilized fillers were prepared using intact and crushed ammonia oxidation granular sludge (AnGS) to compare their effects on the completely autotrophic N-removal over nitrite (CANON) process in domestic sewage. Using pre-aerated domestic sewage as an influent, the effect of granular type on nitrogen removal was investigated under intermittent aeration. The results show that the total nitrogen removal (TNR) of the crushed AnGS immobilized filler was 75.8–80.0% at a dissolved oxygen (DO) concentration of 3 mg/L, while the intact AnGS immobilized filler required a DO of 4 mg/L to achieve the same TNR level. The DO concentration is the key factor affecting the nitrogen removal efficiency, because partial nitrification was affected by the DO concentration. Candidatus Kuenenia was the dominant genus of anaerobic ammonium oxidation (anammox) bacteria, and its relative abundance was higher in the crushed AnGS immobilized filler (21.11%) than in the intact AnGS immobilized filler (9.60%). Furthermore, the immobilized filler could inhibit the growth of nitrite-oxidizing bacteria (NOB), and the relative abundance of Nitrospira, the major NOB genus, decreased after operation. The results of this study indicate that the use of AnGS immobilized filler is a promising strategy to strengthen the CANON process in municipal wastewater treatment.