In this study, FW effluent was used as a substrate for both hydrogen and volatile fatty acids (VFAs) production by a lab scale set up of the semi-continuously running reactor system with a mesophilic fermentation to examine the influence of pH and pretreatment. Repeated measurement analysis showed that the factors (pH and Pretreatment) significantly influenced H-2, VFAs concentration, VFA/soluble chemical oxygen demand (SCOD), and H-2/SCOD traits (P < 0.0001). Duncan comparisons showed that both concentration and yield of H-2 were the highest in the chemical treatment (CT) at pH 7, which were (280.82 +/- 5.72) min, and (4.44 +/- 0.10) ml/g SCOD, respectively. While concentration and yield of the VFAs were the highest in the chemical treatment (CT) at pH 6, which were (55.44 +/- 2.39) g/L, and (926.21 +/- 42.27) mg/g SCOD, respectively. The butyrate and acetate for the optimal blend (pH 6, CT pretreatment) counted for 62.43% of the total VFAs. (C) 2019 Published by Elsevier Ltd on behalf of Hydrogen Energy Publications LLC.