3.4 COD reduction in bioreactor
From Figure-4 it can be seen that the averaged
COD removal efficiency was 48.5%, which is
comparatively lower than the commonly obtained COD
removal from cattle manure (51-79%) [13]. This resul
was believed to be due to the high COD exhibited by the
inoculum which leads to increase in influent COD
concentration. In effect, it dominates the microbial activity
thereby resulting in lower COD removal efficiency. It was
also observed that the majority of the COD treatmen
prevailed in the batch as compared to semi-continuous
operation, but a more stable treatment was found during
the semi-continuous operation. This stability indicates
clearly the benefit of the semi-continuous system.