Effect of the initial pH on the anaerobic digestion process of dairy cattle manure.

Anaerobic digestion (AD) has recently been studied to obtain products of greater interest than biogas, such as volatile fatty acids (VFAs) and phytoregulators. The effect of the initial pH of cow manure and the fermentation time of the AD on the microbial composition, VFAs, indole-3-acetic acid (IAA) and gibberellic acid (GA) production was evaluated. The cow manure (7% solids) was adjusted to initial pH values of 5.