Role of adding dried sludge micropowder in aerobic granular sludge reactor with extended filamentous bacteria

Abstract

This work investigated the extended filamentous bacteria and role of sludge micropowder (prepared from dried municipal wastewater sludge) addition in an aerobic granular sludge-sequencing batch reactor (AGS-SBR). Type 021N strain is one of the dominant extended filaments and remarkably diminished after micropowder addition. Then, sludge volume index (SVI5) value decreased from 172 to 44 mL/g. Micropowder supplemented in the SBR created physical collisions with granules containing extended filaments, improved sludge settleability, and induced microorganisms to secrete more extracellular polymeric substances (EPS), which favored the internal growth of extended filaments and enhanced sludge granulation. Furthermore, pollution removal efficiencies increased and maintained at about 85%. The dosage of sludge micropowder had a positive impact on granulation and reactor operation even at the short-term adding stage.