In contrast to CSTRs, Sequencing Batch Reactors (SBRs) are characterized
by discontinuous, dynamic operation, involving periods
of Fill, React, Waste, Settle, and Draw. Such systems have the
advantage of possessing a large range of operating conditions (easily
obtainable by varying the times of the elements comprising the
operating cycle) and high operational flexibility. They have not,
however, been examined to this point in terms of the impact of
substrate inhibition on process performance. For these bioreactors
operating under dynamic conditions the term ‘‘steady state’’ may
not be entirely appropriate, even if it is widely utilized in the literature.
Multiple steady state conditions (intended to refer to stable
operation conditions in terms of bioreactor performance) can occur
in such systems, and are strongly dependent on the operating conditions
as will be clearly evidenced in this study. A previous report
[12] provided a preliminary description of the behaviour of an SBR
treating xenobiotic substrates, and identified possible design criteria.
The present work represents an in-depth and systematic evaluation
of the influence of substrate inhibition on biodegradation
performance in SBRs, resulting in a powerful guide for identifying
SBR process operability and stability aimed at obtaining high reactor
performance. Additionally, the work also examined two cases
studies of ‘‘real’’ xenobiotic substrate degradation, which were
used to illustrate the impact of degradation kinetic parameters
on SBR process operation.