WASTE-TO-BIOFUELS: VALORIZATION OF FOOD RESIDUE BIOMASS (FORBI) FOR HYDROGEN AND METHANE PRODUCTION

This research work concerns the production of Hydrogen and Methane from a Food Residue Biomass (FORBI) product, generated from pre-sorted Fermentable Household Food Waste in a Continuous Stirred Tank Reactor (CSTR). FORBI is generated by drying and shredding the fermentable fraction of household food waste, collected door-to-door in the Municipality of Halandri, Greece. Hydrogen production from FORBI through anaerobic fermentation under acidogenic mesophilic conditions was carried out using a 4L CSTR (H2-CSTR), operated at 4 hr and 3 hr Hydraulic Retention Times (HRT), with a feed concentration of 15 g TS/L. Volatile fatty acids (VFAs), Total and Volatile Suspended Solids (TSS and VSS), Total and Soluble Chemical Oxygen Demand (tCOD and sCOD), Total and Dissolved Carbohydrates, pH and hydrogen content in the biogas were monitored. The H2-CSTR operated for 32 days. During its operation, the biogas productivity reached 7.78 L/d, out of which 4.13 L/d was hydrogen (60%). This corresponds to a yield of 22Lbiogas/kgFORBI. The conversion of FORBI into methane was carried out through the operation of a CSTR (CH4-CSTR) with working volume 4L (CH4-CSTR). the reactor operated under mesophilic methanogenic conditions at 20,15 and 10 days HRT and an organic loading of 15 g TS/L. TSS, VSS, tCOD, sCOD, pH, alkalinity, VFAs and methane content in the biogas were monitored. The mean methane percentage in the biogas was up to 65%, with an average biogas productivity of 0.5Lbiogas/Lreactor/day, during the optimum operational conditions. The biogas productivity corresponds to a productivity of 477 Lbiogas/kgFORBI. The experimental results obtained were used as a basis for the development of a model by using AQUASIM [1] software, which was able to adequately simulate the operation of the bioreactors. Conclusively, FORBI was proved as a suitable feedstock material both for hydrogen and methane production, resulting in high biogas yields in both cases.