Applied Microbiology and Biotechnology, Vol.89, No.3, 855-865, 2011
Upgrading of straw hydrolysate for production of hydrogen and phenols in a microbial electrolysis cell (MEC)
In a microbial electrolysis cell (MEC), hydrolysate produced by hydrothermal treatment of wheat straw was used for hydrogen production during selective recovery of phenols. The average H-2 production rate was 0.61 m(3) H-2/m(3) MEC center dot day and equivalent to a rate of 0.40 kg COD/m(3) MEC center dot day. The microbial community in the anode biofilm was adapted by establishment of xylose-degrading bacteria of the Bacteriodetes phylum (16%) and Geobacter sulfurreducens (49%). During the process, 61% of the chemical oxygen demand was removed as hydrogen at 64% yield. The total energy production yield was 78% considering the energy content in the consumed compounds and the cell voltage of 0.7 V. The highest hydrogen production was equivalent to 0.8 kg COD/m(3) MEC center dot day and was obtained at pH 7-8 and 25A degrees C. Accumulation of 53% w/v phenolic compounds in the liquor was obtained by stepwise addition of the hydrolysate during simultaneous production of hydrogen from consumption of 95% for the hemicellulose and 100% of the fatty acids. Final calculations showed that hydrolysate produced from 1 kg wheat straw was upgraded by means of the MEC to 22 g hydrogen (266 L), 8 g xylan, and 9 g polyphenolics for potential utilization in biobased materials.