Development of simultaneous nitrification-denitrification (SND) in biofilm reactors with partially coupled a novel biodegradable carrier for nitrogen-rich water purification

Abstract Development of simultaneous nitrification-denitrification (SND) is a promising approach for nitrogen-rich water purification. Coupling biofilm reactors with novel biodegradable carrier of Pumelo Peel (PP) and various conventional plastic fillers (polyurethane filler, SPR-1 suspension filler, TA-II elastic filler and sphere filler) were examined to achieve SND in this study. Results represented that partially coupled with PP could achieve highly efficient SND. Optimal performance appealed in a bioreactor of coupling PP and SPR-1filler with ammonia and total nitrogen removal efficiencies of 96.8 ± 4.0% and 78.9 ± 9.5%, respectively, as well as low effluent COD Mn of 1.85 ± 0.86 mg L −1 . Notably, PP and conventional plastic filler played obviously different roles in combined bioreactor system. Microbial analysis suggested that dominant genera were Thiothrix , Gemmata , unclassified comanonadaceae , unclassified Rhizobiales , Salipiger , Chloronema and Klebsiella in optimal combined bioreactor, which indicated novel co-existence of heterotrophic nitrification, solid-phase, non-solid-phase heterotrophic and sulfur-based autotrophic denitrification for achieving efficient SND.