During this period (days 102–202), severe disturbances were detected in the anaerobic process mainly
due to the high acidity of the influent and to the lack of
alkalinity in the medium. For these reasons, the
conditions imposed on the reactor during the first 2
weeks of this period(HRT andOLR of 2.5 days and
3.3 kg COD/m3
d, respectively) could not be maintained,