Green Hydrogen-Compressed natural gas (bio-H-CNG) production from food waste: Organic load influence on hydrogen and methane fusion

Biogenic hydrogen (bioH2) enriched compressed natural gas (bio-H-CNG or biohythane) is emerging interest due to its feasibility to use in the existing transportation infrastructure with induced environmental benefits. This study evaluated the production of bioH2 and biomethane (bioCH4) towards bio-H-CNG formation at a varying organic load (OL: 30,40,50 g COD/L) of food waste (FW). Acidogenic reactor operated with FW at 40 g COD/L showed the highest cumulative bioH2 production while elevated OL (50 g COD/L) showed higher cumulative bioCH4 production (CMP: 11.92 L) from the methanogenic reactor. BioH2 and bioCH4 produced at different time intervals were combined to assess bio-H-CNG. The nature of biocatalyst and OL significantly regulated the composition of bio-H-CNG varying between 0.1 and 0.3 of H2/(H2+CH4) ratio accounting for 5-12.6 kJ/g COD. Chain elongation, converting short (C2-C4) to medium-chain fatty acids (Caproic acid, 1.16 g/L) was specifically observed during the acidogenic process.

Automated summary

This study evaluated the production of bioH2 and biomethane from food waste at varying organic loads, aiming to form biogenic hydrogen-enriched compressed natural gas. The results show that the composition and energy output of bioH2 and biomethane vary significantly under different organic load conditions.