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Hydrogen production from hydrothermally pretreated (200 °C for 10 min at 16 bar) sugarcane bagasse was analyzed using response surface methodology. The yeast extract concentration and the temperature had a significant influence for hydrogen production (p-value 0.027 and 0.009, respectively). Maximum hydrogen production (17.7 mmol/L) was observed with 3 g/L yeast extract at 60 °C (C10). In this conditions were produced acetic acid (50.44 mg/L), butyric acid (209.71 mg/L), ethanol (38.4 mg/L), and methane (6.27 mmol/L). Lower hydrogen productions (3.5 mmol/L and 3.9 mmol/L) were observed under the conditions C7 (2 g/L of yeast extract, 35.8 °C) and C9 (1 g/L of yeast extract, 40 °C), respectively. The low yeast extract concentration and low temperature caused a negative effect on the hydrogen production. By means of denaturing gradient gel electrophoresis 20% of similarity was observed between the archaeal population of mesophilic (35 and 40 °C) and thermophilic (50, 60 and 64 °C) reactors. Likewise, similarity of 22% was noted between the bacterial population for the reactors with the lowest hydrogen production (3.5 mmol/L), at 35.8 °C and with the highest hydrogen production (17.7 mmol/L) at 60 °C demonstrating that microbial population modification was a function of incubation temperature variation.

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-This present paper reports a study of the efficiency of an anaerobic Baffled Reactor (ABR) composed of three chambers working as the first stage of a biological treatment system for swine wastewater, over a period of 116 days. The average value of the volumetric organic loading rate (VOLR) was 17.8 kgCODtotal m -3 d -1 , the biological organic loading rates (BOLR) based on total and filtered COD influents of 14381 mg L -1 and 3610 mg L -1 , respectively, were: 1.3 kgCODtotal kgTVS d -1 and 0.98 kgCODfiltered kgTVS d -1 , respectively, and the hydraulic loading rate (HLR) was about 1.4 m 3 m -3 d -1 . The average removal efficiency for total COD was 80% at a hydraulic retention time (HRT) of about 18 hours. The average alkalinity in the effluent was 3801 mgCaCO 3 L -1 . The average removal efficiencies for oil and grease and total soluble solids were 41% and 78%, respectively. The sludge granulation and biogas production in the ABR were quite different between the first and third compartment, showing a distinct microbial consortium in each chamber. Through this research it was confirmed that this type of reactor can be employed as the first stage in a system treating swine wastewater.

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Sugarcane bagasse (SCB) was used as a lignocellulosic substrate, combining the co-production of H2 (Stage I) and CH4 (Stage II) by a dark fermentation process in batch reactors.

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