The dynamic characteristics of TP, TN, COD and VFA of the biogas slurry during the fermentation
process of Vetiver plants were shown in Fig.2. There was the greatest effect of sample time on VFA
among these four parameters (Fig.2d). The values of the measured parameters in 2011 were higher than
those in 2012 at the same sampled time (Fig.2d). TP and TN had less changes during the whole
fermentation stages and at the last stage of the process shown munch lower result (Fig.2a and 2b). The
content of COD and VFA also had the above change except the sample V11(Fig.2c and 2d). The results
suggested that the biogas slurry might be used as organic fertilizer.