## 3 Results and Discussion
### Acidogenic Fermentation
#### 3.2.1 pH and Organic Load Effects on BSG Acidogenic Batch Fermentation
\begin{table}
\begin{tabular}{l c c c c c c c c c c c} \hline \hline
**pH** & \multicolumn{3}{c|}{**5.0**} & \multicolumn{3}{c|}{**5.5**} & \multicolumn{3}{c}{**6.0**} \\ \hline
**Organic Load (OL)** & 12.3 & 22.6 & 32.4 & 35.8 & 11.9 & 22.6 & 32.0 & 39.2 & 11.9 & 23.7 & 33.0 & 39.9 \\ (gCOD L\({}^{-1}\)) & (0.4) & (0.6) & (0.6) & (2.9) & (0.3) & (0.4) & (1.5) & (1.3) & (0.5) & (0.7) & (0.1) & (1.2) \\ \hline
**FP produced (FP)** & 6.01 & 11.3 & 13.3 & 18.2 & 6.34 & 11.8 & 15.6 & 20.0 & 6.27 & 12.6 & 17.8 & 23.1 \\ (gCOD-FP L\({}^{-1}\)) & (0.70) & (1.7) & (0.9) & (0.5) & (0.81) & (0.9) & (0.6) & (1.8) & (0.79) & (0.5) & (2.1) & (2.2) \\ \hline
**Y\({}_{\text{FP}}\)** & 0.66 & 0.69 & 0.55 & 0.60 & 0.63 & 0.57 & 0.60 & 0.44 & 0.63 & 0.60 & 0.55 & 0.52 \\ (gCOD-FP gCOD\({}^{-1}\)) & (0.11) & (0.04) & (0.04) & (0.04) & (0.04) & (0.07) & (0.05) & (0.01) & (0.03) & (0.03) & (0.02) & (0.05) \\ \hline
**r\({}_{\text{FP}}\)** & 42.2 & 79.3 & 93.2 & 300 & 45.0 & 82.8 & 170 & 141 & 44.5 & 112 & 125 & 162 \\ (mgCOD-FP L\({}^{-1}\) h\({}^{-1}\)) & (5.9) & (14.9) & (7.5) & (76) & (7.2) & (8.4) & (54) & (15) & (7.1) & (36) & (18) & (19) \\ \hline
**r\({}_{\text{FPmax}}\)** & 270 & 531 & 730 & 915 & 194 & 502 & 555 & 745 & 158 & 383 & 626 & 1096 \\ (mgCOD-FP L\({}^{-1}\) h\({}^{-1}\)) & (34) & (26) & (58) & (85) & (15) & (29) & (14) & (76) & (15) & (38) & (47) & (82) \\ \hline
**-\({}_{\text{fsmax}}\)** & 405 & 785 & 1323 & 1529 & 300 & 869 & 916 & 1692 & 245 & 609 & 1146 & 2104 \\ (mgCOD L\({}^{-1}\) h\({}^{-1}\)) & (82) & (50) & (128) & (119) & (30) & (251) & (299) & (152) & (24) & (83) & (61) & (179) \\ \hline
**q\({}_{\text{FP}}\)** & 2.72 & 4.45 & 5.11 & 16.2 & 2.89 & 4.29 & 9.15 & 9.78 & 2.85 & 6.45 & 6.73 & 10.3 \\ (mgCOD-FP gVSS\({}^{-1}\) h\({}^{-1}\)) & (0.44) & (0.98) & (0.83) & (7.2) & (0.51) & (0.68) & (3.07) & (2.83) & (0.73) & (2.20) & (1.42) & (4.0) \\ \hline
**q\({}_{\text{FPmax}}\)** & 17.1 & 29.8 & 37.3 & 50.2 & 12.4 & 24.5 & 28.4 & 48.0 & 9.40 & 20.2 & 32.4 & 71.6 \\ (mgCOD-FP gVSS\({}^{-1}\) h\({}^{-1}\)) & (3.4) & (4.7) & (7.4) & (15.8) & (1.8) & (6.7) & (9.8) & (5.3) & (1.70) & (3.6) & (6.6) & (24) \\ \hline
**-q\({}_{\text{smax}}\)** & 25.5 & 44.1 & 67.3 & 83.8 & 19.1 & 42.5 & 46.8 & 108 & 14.7 & 32.7 & 59.5 & 133 \\ (mgCOD gVSS\({}^{-1}\) h\({}^{-1}\)) & (3.5) & (1.4) & (0.9) & (7.2) & (0.4) & (5.8) & (7.7) & (4) & (1.6) & (1.2) & (2.5) & (13) \\ \hline
**Degree of fermentation (DF)** & 0.49 & 0.50 & 0.41 & 0.51 & 0.53 & 0.52 & 0.49 & 0.51 & 0.52 & 0.53 & 0.54 & 0.58 \\ (gCOD-FP gCOD\({}^{-1}\)) & (0.04) & (0.06) & (0.03) & (0.06) & (0.06) & (0.04) & (0.03) & (0.03) & (0.05) & (0.01) & (0.07) & (0.05) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Summary of the results obtained for each acidogenic batch assay. The values listed are averages \(\pm\) standard deviation (values in brackets). HProp, HVal and HIsoval concentrations were higher at pH 6.0. [PERSON] et al. [36] also reported higher concentrations of HProp at pH 6.0 when assessing the effect of pH (3.5-6.0) on the acidogenic fermentation of whey in continuous reactor. Low concentrations of HLac, HVal, HIsov and ethanol were also detected (Figure 3a). [PERSON] et al. [37], have also reported HAc and HBut as being the main acids produced from a synthetic soft drink wastewater under acidic conditions (3.9 \(<\) pH \(<\) 5.2). [PERSON] et al. [38], who investigated the influence of pH in the fermentation of glucose, also achieved HBut and HAc as the main organic acids produced from glucose fermentation within the pH range of 4.0 to 6.5. Figure 3: (**a**) Fermentation products produced and (**b**) fermentation products profile obtained at each different pH (5.0, 5.5 and 6.0) and at each different organic load (10, 20, 30 and 40 gCOD L\({}^{-1}\)); (**c**) Estimated PHA precursors at each condition tested. Error bars represents standard deviations. Furthermore, in the latter study HLac was detected at low pH (4, 4.75 and 5), which was also observed in the present study at pH 5.0 for the OL of 30 and 40 gCOD L\({}^{-1}\). [PERSON] et al.