Enhancing bio-CH4 yield through co-digestion of Food Waste and Swine Manure in Leachate Bed Reactors through different recirculation rates

Different recirculation rates of 6, 12, and 24 L.day-1 were evaluated in a Leachate Bed Reactor (LBR). Operation with 10 gST.L-1 food waste and 06 L.d-1 recirculation lasted 27 days, assuming complete CH4 decay in biogas. Max CH4 yield occurred after 13 days, reaching 3.94 mL g-1 STadd and max 79% of total biogas. Besides CH4, H2 production was observed, especially in the reactor's exponential phase (until day 2), with 22.69% of this gas, along with 47.38% CO2 and only 16.92% CH4. After this stage, H2 and CO2 were likely used as substrates by hydrogenotrophic archaea for CH4 production. It can be inferred that the organic load used was close to the limit of the system operated at 10 gST.L-1 and 06 L.d-1 recirculation.