The pH profiles obtained during the fermentation of SDW are shown in Fig. 3. As expected, increasing the F/M produced, on average, lower pH values during the first phase of the process, during which most of the VFA production occurred. Within the same F/M group, pH increased with initial alkalinity. Even with all the assays starting approximately at the same pH, the ranges of F/M and alkalinity used in this study were large enough to generate substantial variability in the pH profiles. This made it possible to study the role of pH when pH control is absent, which is an aspect of the acidification process that has not been thoroughly investigated.