A glimpse of the re-granulation process after artificially crushing anammox granular sludge

The granular sludge is considered a suitable sludge type for the anammox process. Although granule formation has been widely investigated, few studies focus on the feature of re-granulation. In this study, two artificially crushing methods, Zirconia balls shake and blender stir, were compared, and the following re-granulation periods were monitored. Results showed that, after Zirconia balls shaking, the average particle size was increased from 52.11 to 107.20 μm within 40 days, and during that, total nitrogen removal efficiency (TNRE) was kept at 50.74 %, and the abundance of Candidatus Brocadia was increased by 81.5 %. Correspondingly, after blender stirring, the average particle size was merely raised from 30.88 to 53.47 μm within 30 days, accompanied by TNRE dropped to 22.18 %, but the abundance of Candidatus Brocadia rose by 165 %. Furthermore, the crushing re-granulation strategy helped wash out undesired nitrite-oxidizing bacteria.