Effects of Anaerobic Durations on the Nitrogen and Phosphorus Removal Efficacy of a Dual PAOs Synergistic EBPR System under Low Carbon Condition
In this study,an alternated anaerobic/oxic sequencing batch reactor(SBR)fed with mixed amino acids(glu-tamic acid,aspartic acid,glycine,and proline)was employed to explore the impact of anaerobic duration on the nitro-gen and phosphorus removal efficacy in a dual PAOs(polyphosphate-accumulating organisms)synergistic enhanced biological phosphorus removal(EBPR)system under low-carbon conditions.The results indicated that with the ex-tension of the anaerobic duration,the phosphorus removal performance has been significantly increased.The phos-phorus removal efficiency stability reached above 80％at the 4 h anaerobic duration,while the ammonia nitrogen re-moval efficiency gradually increased to over 80％till the endof the stage.High-throughput 16S rRNA sequencing re-sults revealed that fermentative PAOs such as Tetrasphaera,which prefer using some complex organic molecules such as mixed amino acids,synergized with conventional PAOs for phosphorus removal.However,both nitrogen and phosphorus removal performance performed a kind of fluctuation at the 8 h anaerobic duration.The abundances of Tetrasphaera and Accumulibacter increased initially and then decreased with the prolonged anaerobic periods,while the abundance of nitrifying bacteria generally increased.Overall,extending the anaerobic durationwas conducive to establishing the synergistic phosphorus and nitrogen removal pattern.Nevertheless,a 4 h anaerobic duration was considered to be more rational for the dual PAOs synergistic EBPR system under low-carbon conditions for the pur-pose of stability and long-term operation of the system.
synergismEBPRnitrogen and phosphorus removalanaerobic time
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