Influence of inoculum-to-substrate ratio on biogas enhancement during biochar-assisted co-digestion of food waste and sludge

Hydrothermal pretreatment of food waste enhances performance of anaerobic co-digestion with sludge

Food waste (FW) presents a significant opportunity for renewable energy production through anaerobic digestion (AD) when subjected to appropriate treatment. This study investigates the impact of thermal hydrolysis pretreatment (THP) on FW at varying temperature levels (90 °C, 120 °C, and 140 °C) prior to mesophilic anaerobic co-digestion with sewage sludge (SS). Results demonstrate enhanced FW hydrolysis at 120 °C, leading to a cumulative methane yield of 324.39 ± 4.5 mL/gVSadd, representing a 41.75% increase over untreated FW (228.83 ± 1.13 mL/gVSadd). Shifts in microbial communities, particularly Methanosarcina, Methanobactrium, and Methanobrevibacter, support efficient methanogenesis. Co-digestion of FW pretreated at 120 °C yields maximum energy production of 11.48 MJ/t, a 49.47% improvement compared to untreated processes. The economic analysis underscores the profitability of co-digestion with FW pretreated at 120 °C. These findings highlight the potential for enhanced methane production and energy conversion efficiency with hydrothermally pretreated FW and SS co-digestion.

Approach to anaerobic bio-degradation of natural and synthetic fabrics: Physico-chemical study of the alteration processes

In this paper, the mesophilic Biochemical Methane Potential of several fabrics was assessed at different Total Solid concentrations (1-4%TS). Physico-chemical techniques were applied to explore the arising structural changes on fibers during the anaerobic digestion process. Additionally, the modified Gompertz model was used to assess and compare the AD performance of the fabrics. In cellulose-based fibers the production of biogas was enhanced thanks to the easy solubilization of acetate, which is generated upon partial breakage of cellulose bonds. The crystallinity of vegetal fibers decreased significantly from day 19. The highest methane yields were attained for silk and wool fabrics at the lowest TS concentrations. Conformational changes in fibroin and keratin were detected. The highest degrees of degradation were observed in solid samples with lower solid concentrations. Accordingly, the maximum methane yields were reported in the reactors operating with lower TS.