Dark Fermentative Hydrogen Production from Xylose in Different Bioreactors Using Sewage Sludge Microflora

Abstract

In this study, the H2-producing activity of the sewage sludge microflora using xylose as the sole carbon substrate was investigated in three bioreactor systems, including a suspended continuously stirred tank reactor (CSTR), an immobilized-cell continuously stirred anaerobic bioreactor (IC-CSABR), and a powder activated carbon-assisted agitated granular sludge bed (AGSB). For suspended-culture CSTR operations, fermentative H2 production was conducted at different hydraulic retention times (HRT = 4–12 h). The H2 production rate (HPR) was 183 mmol/L/d at HRT = 12 h, but the H2 production rate and yield decreased significantly when the HRT was shortened to 4 h due primarily to the washout of cells. To improve the operational stability of short HRTs, silicone-immobilized cells (IC-CSABR system) and powder activated carbon carriers (AGSB system) were adopted for the reactor systems to either maintain stable biomass concentration in the reactor or enhance biomass content by stimulating sludge granulation. Both ...