To our knowledge, this is the second study of phenol degradation by vetiver grass, but it is the first that systematically reveals the complete phenol degradation mechanism by vetiver grass in real wastewater. Our proposed mechanism is different from that reported by Singh et al. (2008), who conducted there experiment in aseptic Murashige and Skoog liquid medium, in which rhizomicrobes might not play substantial role in phenol degradation. In addition, Singh et al. (2008) did not conduct their phenol degradation study until phenol was completely degraded to meet the discharge standard. Thus, they might not have noticed phase II of the degradation mechanism in which vetiver rhizomicrobes substantially increase the rate of phenol detoxification.