## 2 Materials and Methods
### Experimental Set-Up and Procedure  
All experiments were performed in 1 L double wall, stainless steel (INOX 316) bioreactors at mesophilic conditions, as described in detail by [PERSON] et al. [5]. Physicochemical characterization of the substrates and the batch tests effluents was performed. During the experimentation period samples were taken every 4-6 h depending on the progress of the experiment.  
TS, VS, TSS, VSS, t-COD, d-COD, TKN, ammonium N, t-P, and d-P were measured according to Standard Methods [27]. Total and dissolved carbohydrates were determined according to [PERSON] [28], while off-line pH values were measured by Orion ROSS Ultra  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameter** & **Used DN Hydrolase (g/L)** & \multicolumn{3}{c}{**EFPs (g/kg)**} & \multicolumn{3}{c}{**Mixture after Hydrolysis (g/L)**} \\ \hline pH & 7.40 & \(\pm\)0.01 & N/A & & 4.21 & \(\pm\)0.03 \\ t-Carbohydrates & 3.50 & \(\pm\)1.70 & 183.80 & & \(\pm\)37.20 & 31.59 & \(\pm\)8.42 \\ d-Carbohydrates & 0.06 & \(\pm\)0.01 & & N/A & & 12.24 & \(\pm\)0.18 \\ t-COD & 5.01 & \(\pm\)1.68 & 663.27 & & \(\pm\)86.59 & 49.95 & \(\pm\)6.41 \\ d-COD & 0.40 & \(\pm\)0.01 & & N/A & & 20.42 & \(\pm\)1.45 \\ TS & 8.17 & \(\pm\)0.52 & 554.51 & & \(\pm\)58.60 & 42.37 & \(\pm\)0.85 \\ VS & 6.51 & \(\pm\)0.55 & 509.20 & & \(\pm\)7.13 & 32.95 & \(\pm\)0.95 \\ TSS & 6.70 & \(\pm\)0.01 & & N/A & & 22.03 & \(\pm\)0.35 \\ VSS & 6.16 & \(\pm\)0.31 & & N/A & & 22.00 & \(\pm\)0.30 \\ TKN & 0.07 & \(\pm\)0.02 & 3.92 & & \(\pm\)0.42 & 0.91 & \(\pm\)0.06 \\ NH\({}_{3}\)-N & 0.07 & \(\pm\)0.01 & 2.65 & & \(\pm\)0.06 & 0.25 & \(\pm\)0.02 \\ Oil \& Grease & 0.02 & \(\pm\)0.01 & 47.00 & & \(\pm\)1.38 & 3.14 & \(\pm\)0.14 \\ t-P & 0.05 & \(\pm\)0.01 & 1.24 & & \(\pm\)0.25 & 2.16 & \(\pm\)0.07 \\ d-P & 0.02 & \(\pm\)0.01 & & N/A & & 0.87 & \(\pm\)0.01 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Physicochemical characteristics of used DNs hydrolysate, EFPs, and their mixture after hydrolysis (mean value \(\pm\) standard deviation of three measurements).  
Refillable pH/ATC Triode, Thermo Scientific. Lactic acid was measured with a DIONEX IC300 ion chromatography as described by [PERSON] et al. [5] while ethanol and VFAs were analyzed through gas chromatography (Agilent Technologies, Sant Clara, CA, USA, 7890A) equipped with a flame ionization detector, as described by [PERSON] et al. [29]. Oil and grease were determined using hexane and a Soxhlet extractor (Velp Scientific, Usmate Velate MB, Italy, SER 148). The biogas volume was measured by custom-made equipment and converted to standard conditions (STP = 0 \({}^{\circ}\)C and 1 atm) while the biogas analysis was performed by gas chromatography, according to [PERSON] et al. [4].  
Concerning the calculation of normalized cumulative H\({}_{2}\) production per L of reactor, the produced hydrogen was converted to STP conditions and divided by the working volume of the reactor. The calculation for the H\({}_{2}\) production yield was carried out from the produced H\({}_{2}\) (NL) converted to moles (22.4 NL/mol H\({}_{2}\)) divided by the mol of consumed carbohydrates in glucose equivalents.