Hydrogen Production from Rice Winery Wastewater by Using a Continuously-Stirred Reactor

Abstract

The continuous production of hydrogen from rice winery wastewater in a continuously stirred tank reactor (CSTR) was investigated. The conversion efficiency of carbohydrate increased with the hydraulic retention time (HRT), but slightly decreased with the increase of the substrate concentration. The conversion of carbohydrate followed the Monod kinetics with a maximum rate of 1.34 g/(g-VSS·d) and a half-rate constant of 0.32 g/L. The overall production rates of volatile fatty acids (VFAs) and ethanol decreased with HRT, but increased with the substrate concentrations. The key acidogenic products were acetate, propionate, butyrate, and ethanol. Biogas produced under all test conditions was composed of hydrogen (37–52%) and carbon dioxide (46–60%). The specific hydrogen production rate increased with substrate concentration, but with the decrease of HRT. The hydrogen yield was in the range of 1.02–1.37 mol/mol-hexose. This CSTR has potential for the use in the hydrogen production from rice winery wastewater.