Enhanced dark fermentative hydrogen production from waste activated sludge by combining potassium ferrate with...

Alkaline pretreatment was demonstrated to be effective in the enhancement of hydrogen production. However, the sludge solubilization rate of alkaline pretreatment is still limited. This study reports a new strategy of K₂FeO₄ + pH 9.5 for sludge mesophilic anaerobic fermentation. Experimental results showed that the combination of K₂FeO₄/pH 9.5 pretreatment had a greater hydrogen yield than the individual K₂FeO₄ and pH 9.5. The maximum hydrogen yield was 19.2 mL per gram volatile suspended solids (VSS) under the optimal condition (0.02 g per gram total suspended solids K₂FeO₄ + pH 9.5). Kinetic analysis showed that the highest hydrogen production potential of 19.9 mL/g VSS was obtained in the combined reactor, which well fitted the first-order kinetic model (R² = 0.9925). Besides, the fermentation type was mainly acetic and butyric in the combined reactor, which contributed to hydrogen production. Further analyses showed that the combined pretreatment reduced hydrogen sulfide yield, providing an environmentally friendly method to sludge treatment.