p-Nitrophenol (PNP) Removal in an Upflow Anaerobic Sludge Blanket (UASB) Reactor

In this study, co-metabolism reduction of p-nitrophenol (PNP) under anaerobic condition was investigated in an upflow anaerobic sludge blanket (UASB) reactor. p-Aminophenol (PAP) was identified as the dominant product of PNP reduction in UASB, and no further degradation of PAP was observed under anaerobic condition in UASB. The performance of three cosubstrates, namely sodium acetate, glucose and methanol, was compared, demonstrating that sodium acetate had the best performance as the external cosubstrate. Both PNP removal and PAP formation increased with the increase of acetate concentrations and the increase of hydraulic retention times (HRTs). Both PNP removal and PAP formation was significantly influenced by initial PNP concentration, exhibiting the inhibitory nature of PNP.