Complete Nutrient Removal Coupled to Nitrous Oxide Production as a Bioenergy Source by Denitrifying Polyphosphate-Accumulating Organisms

Han Gao, Miaomiao Liu, James S. Griffin, Longcheng Xu, Da Xiang, Yaniv D. Scherson, Wen Tso Liu, George F. Wells

Research output: Contribution to journalArticlepeer-review

Abstract

Coupled aerobic-anoxic nitrous decomposition operation (CANDO) is a promising emerging bioprocess for wastewater treatment that enables direct energy recovery from nitrogen (N) in three steps: (1) ammonium oxidation to nitrite; (2) denitrification of nitrite to nitrous oxide (N2O); and (3) N2O conversion to N2 with energy generation. However, CANDO does not currently target phosphorus (P) removal. Here, we demonstrate that denitrifying polyphosphate-accumulating organism (PAO) enrichment cultures are capable of catalyzing simultaneous biological N and P removal coupled to N2O generation in a second generation CANDO process, CANDO+P. Over 7 months (>300 cycles) of operation of a prototype lab-scale CANDO+P sequencing batch reactor treating synthetic municipal wastewater, we observed stable and near-complete N removal accompanied by sustained high-rate, high-yield N2O production with partial P removal. A substantial increase in abundance of the PAO Candidatus Accumulibacter phosphatis was observed, increasing from 5% of the total bacterial community in the inoculum to over 50% after 4 months. PAO enrichment was accompanied by a strong shift in the dominant Accumulibacter population from clade IIC to clade IA, based on qPCR monitoring of polyphosphate kinase 1 (ppk1) gene variants. Our work demonstrates the feasibility of combining high-rate, high-yield N2O production for bioenergy production with combined N and P removal from wastewater, and it further suggests a putative denitrifying PAO niche for Accumulibacter clade IA. (Chemical Equation Presented).

Original languageEnglish (US)
Pages (from-to)4531-4540
Number of pages10
JournalEnvironmental Science and Technology
Volume51
Issue number8
DOIs
StatePublished - Apr 18 2017

ASJC Scopus subject areas

  • Chemistry(all)
  • Environmental Chemistry

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