Metabolism and kinetic study of bioH(2) production by anaerobic sludge under different acid pretreatments

Abstract

This study presents results pertaining to bioH(2) production carried out in batch experiments under different inorganic acid pretreatments of sludge. The sludge was collected from an anaerobic digester and was subjected to different acid (H2SO4, H3PO4, HNO3, and HCl) pretreatments at pH 3 for 24 h. The results showed that electron equivalent balance closure was within -12 to +10 for all experiments; the portion of electrons as bioH(2) fluctuated from 16 to 25. H2SO4 pretreatments significantly increased H-2 yields to 3.3 mol H-2/mol glucose followed by HNO3, HCl, and H3PO4 pretreatments which averaged 2.5 +/- 0.5. Enthalpy (Delta H degrees) and Gibb's free energies (Delta G degrees) fluctuated from 120.5 to 192.7 (kJ/mol) and from -2.2 to -5.9 (kJ/mol). The modified Gompertz was assessed and determined that the maximum bioH(2) production potential, 1551 mL and maximum rate of bioH(2) production, 303 mL/h occurred using the H2SO4 pretreatment.