Bioproducts from anaerobic co-digestion of organic fraction of municipal solid waste: substrate mixing ratios for power, heat and digestate potential assessment as support for scale-up

Abstract

Thisresearch investigated the use offood waste - FW and garden waste - GWas substrates for producing thermic and electric energy on a labbioreactor. A mesophilic continuous stirred-tank reactor (CSTR) was used to support the operational planning of a pilot-scale Plant, consisting indigesters of 430 m3. The bioreactor was operated during 284 days under organic loading ratesfrom1.4 to 3.9 kg VS/m3. d and using different FW:GW ratios to simulate cities routine. The operation of the CSTR showed pH stability, high efficiency of solids removal (74.8 to 97.3%), and a maximum methane yield of 0.51 L CH4/gVS. Considering the most efficient scenario, it was calculated an electric and thermic energy potential of 183 kWheand 554 kWhtper ton of fresh matter. Regarding to the energy yield, up to 18.5 kJ/g VS was estimated. The composite sample of the digestate revealed nitrogen, sodium and potassium as major compounds (1530, 1350, and 1300 mg/L, respectively),and heavy metals under safe limits.As future scope, the presented energy simulations through metane-based energy production system may serve as a boosting step for Biogas Plants, providing valuable references for real scale applications from different proportions of organic urban residues.