Co-Digestion Of Kitchen Waste With Grass And Leaves After Hyperthermophilic Pretreatment For Methane And Hydrogen Production

The study investigated co-digestion batch experiments using kitchen waste (KW) and garden waste (GW) collected from individual households. Grass and leaves were first subjected to a 3-day hyperthermophilic pretreatment at 70 degrees C and 80 degrees C and then co-digested with kitchen waste at 35 degrees C and 55 degrees C. The hyperthermophilic pretreatment resulted in the solubilization of organic material with the release of fatty acids, whereas the biogas yield was negligible. In the second stage, the greatest methane yield of 387 NmL/gVS was achieved for the mono-digestion of leaves, whereas the co-digestion of grass with 50% KW gave the highest hydrogen production of 88 NmL/gVS. Considering the overall process performance, the best operating conditions were established using a 3-day hyperthermophilic pretreatment at 70 degrees C, followed by co-digestion at 55 degrees C in the second stage for the mixture of 25% garden waste with 75% KW.