Again there was the recovery after initial reduction in the removal
efficiency. Removal of benzene was consistently greater
than 98% after day 111 as shown in Fig. 1. In this phase also, similar
response as that in phase II was observed. The maximum removal
efficiency of benzene, toluene, ethyl benzene and o-xylene was
98.86%, 98.97%, 97.67% and 95.60%, respectively. Biodegradation
in Phase III is relatively lesser to Phase II. In case of o-xylene, quite
significant changes were observed in removal efficiency. It has decreased
from 98.168% to 95.60%. Performance study was then extended
to phase IV and V for evaluating the rapid changes in the
influent conditions and very high contamination load to the
reactor.