Nutrient removal performance and microbial community structure in an EBPR system under the limited filamentous bulking state

Limited filamentous bulking (LFB) was proposed to be a new method for saving energy and improving effluent quality. In order to validate the stability of LFB in enhanced biological phosphorus removal (EBPR) systems, the LFB was further achieved in a lab-scale EBPR. Nutrient removal performance and microbial community structure including dominant filaments and polyphosphate-accumulating organisms (PAOs) were investigated. Results showed that the enriched PAOs could alleviate the negative effect of low dissolved oxygen concentration on sludge settleability, making the LFB be more easily achieved and maintained in the EBPR for long-term operation. Sludge volume index was kept between 150–200 mL/g during the LFB period. Larger floc size (⩾400 μm) was commonly observed under the LFB state, which significantly enhanced the simultaneous nitrification and denitrification (SND) efficiency. An average SND efficiency of 36% was observed in the EBPR system when the LFB occurred.