Performance and microbial community in a single-stage simultaneous carbon oxidation, partial nitritation, denitritation and anammox system treating synthetic coking wastewater under the stress of phenol

Abstract As a highly toxic pollutant, phenol is typically present in some high-strength nitrogenous wastewater. In this study, a synthetic coking wastewater with 400 mg L−1 ammonia-nitrogen and 50–250 mg L−1 phenol was treated. Results showed that simultaneous carbon oxidation, partial nitritation, denitritation and anammox (SCONDA) was successfully achieved by step-wise phenol addition. At 200 mg L−1 phenol, 99.8% phenol, 97.5% COD and 89.8% nitrogen could be together removed. However, further increase in phenol concentration caused significant deterioration of the short-terms nitrogen removal efficiency. High-throughput sequencing revealed remarkable evolution in microbial biodiversity, community composition, especially functional species at different phenol concentrations. When the phenol addition was increased from 200 to 250 mg L−1, the relative abundance of Candidatus Kuenenia as predominant anammox species decreased by 87.1%, while phenol-degrading bacteria was increasingly abundant. Furthermore, the removal mechanism of phenol and nitrogen was elucidated by the collaboration among different key functional microbial consortia.