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 (35 o C) 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 (35 o C), 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.