Turning cellulose waste into electricity: hydrogen conversion by a hydrogenase electrode.

Hydrogen-producing thermophilic cellulolytic microorganisms were isolated from cow faeces. Rates of cellulose hydrolysis and hydrogen formation were 0.2 mM L(-1) h(-1) and 1 mM L(-1) h(-1), respectively. An enzymatic fuel cell (EFC) with a hydrogenase anode was used to oxidise hydrogen produced in a microbial bioreactor. The hydrogenase electrode was exposed for 38 days (912 h) to a thermophilic fermentation medium. The hydrogenase activity remaining after continuous operation under load was 73% of the initial value

Scheme of the developed bioreactor cell.

<p>MPDBP - pyrrole derivative N-methyl-N’-(12-pyrrol-1-yldodecyl)-4,4’-bipyridinium ditetrafluoroborate.</p

Dynamic of changes in the open circuit potential values.

<p>The cultivation time of hydrogen-producing bacteria in the bioreactor cell was 25 days (overpressure in the bioreactor – 0.5 atm, pH 6.7–7.0, 60 °C).</p

Hydrogen production by the selected microbial consortium using different types of substrates.

<p>1 – glossy white paper; 2 – glossy paper with print; 3 – glossy colour printed paper; 4 – white newsprint paper; 5 – newsprint with print; 6 – colour newsprint paper; 7 – wheat bran; 8 – kitchen waste; 9 – grains; 10 – yeast; 11 – wood sawdust; 12 – straw; 13 – pretreated filter paper; 14 – filter paper. The cultivation time was 7 days.</p

Electron micrograph of the cellulose.

<p><b>T</b>he isolated microorganisms immersed in exopolysaccharide matrix on the surface of cellulosic fibers (7 days of cultivation).</p

Dependence of power output on overvoltage of the oxygen-hydrogen fuel cell combined with a bioreactor.

<p>The cultivation time of hydrogen-producing bacteria in the bioreactor cell was 38 days (25th day – black curve; 29th day – red curve; 34th day – green curve; 38th day – yellow curve, overpressure in the bioreactor – 0.5 atm, pH 6.7–7.0, 60 °C).</p

Electron micrograph of the cellulose.

<p>The initial stage of cellulose colonisation by isolated microorganisms (3 days of cultivation).</p