Effect of S-TE (solubilization by thermophilic enzyme) digestion conditions on hydrogen production from waste sludge

S-TE (solubilization by thermophilic enzyme) digestion was always used for waste sludge solubilization and reduction with the theory of lysis enzyme secreted by thermophilic bacteria. The effects of pretreated times, pH and sludge concentrations on S-TE digestion were investigated to determine the optimum S-TE conditions on hydrogen fermentation from waste sludge. The experimental results showed that the protein, carbohydrate and SCOD (soluble chemical oxygen demand) were released after S-TE pretreatment, and the optimal conditions on sludge solubilization were 12–16 h, pH 7–9 and 4.31 g/L TSS, respectively. The optimal S-TE conditions on hydrogen yields were 8 h, pH 6 and 6.83 g/L TSS (total suspended solid), and the maximum hydrogen yields were 30.80 ml/g VSS (volatile suspended solid), 33.75 ml/g VSS and 42.90 ml H2/g VSS, respectively. It was concluded that the optimal S-TE digestion conditions on sludge solubilization were different from that on hydrogen production.