Utilization of food waste for bio-hydrogen and bio-methane production: influences of temperature, OLR, and in situ aeration

Dark fermentation of food leftovers for hydrogen production has been studied using a two-stage upflow anaerobic biofilter reactor. To determine the optimum temperature for hydrogen production, the two reactors were operated in parallel at two different temperatures: 35 °C and 45 °C as suitable for prevailing ambient temperature in Egypt. The results indicated that hydrogen production at 45 °C was higher than that at 35 °C. To determine the optimum organic loading rate, a comparative study was carried out using two different OLRs: 10- and 20-g COD/L day. The system was run in a consecutive manner. The first bioreactor for H2 production and the second for CH4 production. Under optimal temperature (45 °C), the hydrogen production rates were 51.9 mL/L day and 10 mL/L day for OLRs 20- and 10-g COD/L day, respectively. When a drop in H2 production occurred, in situ aeration for 24 h was carried out to deactivate methanogens. The total energy production was improved by combining H2 and CH4 bioreactors.