title: Continuous Hydrogen Production from Agricultural Wastewaters at Thermophilic and Hyperthermophilic Temperatures.
abstract: The objective of this study was to investigate the effects of hydraulic retention time (HRT) (8 to 0.5 h) and temperature (55 to 75 °C) in two anaerobic fluidized bed reactors (AFBR) using cheese whey (AFBR-CW = 10,000 mg sugars L-1) and vinasse (AFBR-V = 10,000 mg COD L-1) as substrates. Decreasing the HRT to 0.5 h increased the hydrogen production rates in both reactors, with maximum values of 5.36 ± 0.81 L H2h-1L-1in AFBR-CW and 0.71 ± 0.16 L H2h-1L-1in AFBR-V. The optimal conditions for hydrogen production were the HRT of 4 h and temperature of 65 °C in AFBR-CW, observing maximum hydrogen yield (HY) of 5.51 ± 0.37 mmol H2g COD-1. Still, the maximum HY in AFBR-V was 1.64 ± 0.22 mmol H2g COD-1at 4 h and 55 °C. However, increasing the temperature to 75 °C reduced the hydrogen production in both reactors. Methanol and butyric, acetic, and lactic acids were the main metabolites at temperatures of 55 and 65 °C, favoring the butyric and acetic metabolic pathways of hydrogen production. The increased productions of lactate, propionate, and methanol at 75 °C indicate that the hydrogen-producing bacteria in the thermophilic inoculum were inhibited under hyperthermophilic conditions.
authors.affiliation: Department of Chemical Engineering, Federal University of São Carlos, Rod. Washington Luis, km 235, São Carlos, SP, 13565-905, Brazil.
authors.forename: Lucas Rodrigues
authors.initials: LR
authors.lastname: Ramos
authors.affiliation: Department of Chemical Engineering, Federal University of São Carlos, Rod. Washington Luis, km 235, São Carlos, SP, 13565-905, Brazil. edsilva@ufscar.br.
authors.forename: Edson Luiz
authors.initials: EL
authors.lastname: Silva
mesh_terms: D000383:Agriculture; D019149:Bioreactors / Q000382:microbiology*; D006358:Hot Temperature; D006859:Hydrogen / Q000378:metabolism*; D062065:Wastewater / Q000382:microbiology*
chemical_list: D006859:Hydrogen; D062065:Wastewater
keywords: Biohydrogen; Cheese whey; Hydraulic retention time; Hyperthermophilic fermentation; Organic loading rate; Sugarcane vinasse; Thermophilic fermentation