Fig. 2From: Microbial diversity and community structure of denitrifying biological filters operated with different carbon sourcesConcentrations of COD, NO3-N and NO2-N along the flowpath of each DNBF (n = 30). R1, R2 and R3 were acetate, ethanol and methanol-fed DNBF, respectively. The water samples of flowpath are in the sequence WS inf –WS1–WS2–WS eff Back to article page