Furthermore, physical hindrance caused by
accumulation of inorganic matter inside the bioreactor is
determined by the VS/TS ration. VS/TS ration during the
entire operation was averagely 0.2 with little variation.
This implies that no accumulation of grit was occurred and
the bacteria populations are in favourable condition even
while pH was unregulated. It was reported by Chae et al.,
[12] that the VS/TS ratio of digester is an excellent
indicator to ascertain the accumulation of unwanted
materials and the adequacy of mixing system employed.
Thus, these results denote that the bioreactor is under
adequate mixing.