Anaerobic treatment of glycerol for methane and hydrogen production

This work focused on glycerol exploitation for biogas and hydrogen production. Anaerobic digestion
of pure glycerol was studied in a continuous stirred tank reactor (CSTR), operated under mesophilic
conditions (35oC) at various organic loading rates. The overall operation of the reactor showed that it
could not withstand organic loading rates above 0.25 g COD L-1 d-1, where the maximum biogas
(0.42 ± 0.05 L (g COD)-1) and methane (0.30 ± 0.04 L (g COD)-1) production were achieved.
Fermentative hydrogen production was carried out in batch reactors under mesophilic conditions
(35oC), using heat-pretreated anaerobic microbial culture as inoculum. The effects of initial
concentration of glycerol and initial pH value on hydrogen production were studied. The highest yield
obtained was 22.14 ± 0.46 mL H2 (g COD added)-1 for an initial pH of 6.5 and an initial glycerol
concentration of 8.3 g COD L-1. The main metabolic product was 1.3 propanediol (PDO), while
butyric and acetic acids as well as ethanol, at lower concentrations, were also determined.