Novel synergistic metabolic processes for phenanthrene biodegradation by a nitrate-reducing phenanthrene-degrading culture and an anammox culture

•An anammox culture that can own activity in the presence of PHE is newly discovered.•Anammox can increase anaerobic PHE biodegradation efficiency by ∼1.94 folds.•The inhibitory effects of PHE on anammox cultures were newly discussed.•The nitrite inhibitory effects on PHE-degrading nitrate-reducers were newly discussed.•Novel synergistic metabolic processes for PHE biodegradation are discussed.