Hydrogen production from wastewater by acidogenic granular sludge.
Sludge was granulated in a hydrogen-producing acidogenic reactor when operated at 26 degrees C, pH 5.5 treating a sucrose-rich wastewater. The influence of hydraulic retention time (HRT) and sucrose concentration on hydrogen production by the acidogenic granular sludge was investigated at a constant loading rate of 25 g-sucrose/(l x day). Results show that the gas composition was not greatly influenced by HRT or sucrose concentration. The hydrogen accounted for 57% to 68% of the biogas at HRT ranging 4.6-28.6 h and sucrose concentration ranging 4,800-29,800 mg/l. However, the hydrogen yield was more dependent on HRT and sucrose concentration. It ranged from 0.19 to 0.27 l/g-sucrose with the maximum yield occurring at HRT 13.7 h and sucrose concentration 14,300 mg/l in the wastewater. The acidified effluent was composed of volatile fatty acids and alcohols. The predominant products were butyrate (59-68%) and acetate (10-25%), plus smaller amounts of i-butyrate, valerate, i-valerate, caproate, methanol, ethanol, propanol, and butanol. The sludge yield averaged 0.2 g-VSS/g-sucrose. The carbon balance was 98-107% throughout the study.
Liu
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Centre for Environmental Engineering Research, Department of Civil Engineering, The University of Hong Kong, Pokfulam Road, Hong Kong.
Fang
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D001421:Bacteria, Anaerobic; D006859:Hydrogen / Q000032:analysis*; D006863:Hydrogen-Ion Concentration; D013395:Sucrose / Q000378:metabolism; D013696:Temperature; D014865:Waste Disposal, Fluid / Q000379:methods*
D013395:Sucrose; D006859:Hydrogen