Biohydrogen production from tequila vinasses using a
fixed bed reactor
Germán Buitrón, Dorian Prato-Garcia and Axue Zhang
ABSTRACT
In Mexico, the industrial production of tequila leads to the discharge of more than 31.2 million of m
3
of vinasse, which causes serious environmental issues because of its acidity, high organic load and
the presence of recalcitrant compounds. The aim of this research was to study the feasibility of a
fixed bed reactor for the production of biohydrogen by using tequila vinasse as substrate. The
experiments were carried out in a continuous mode under mesophilic and acidic conditions. The
maximum hydrogen yield and hydrogen production rate were 1.3 mol H
2
mol/mol glucose and
72 ± 9 mL H
2
/(L
reactor
h), respectively. Biogas consisted of carbon dioxide (36%) and hydrogen (64%);
moreover methane was not observed. The electron-equivalent mass balance fitted satisfactorily (sink
of electrons from 0.8 to 7.6%). For vinasses, hydrogen production accounted for 10.9% of the total
available electron-equivalents. In the liquid phase, the principal metabolites identified were acetic,
butyric and iso-butyric acids, which indicated a butyrate–acetate type fermentation. Tequila vinasses
did not result in potential inhibition of the fermentative process. Considering the process as a water
treatment system, only 20% of the original carbon was removed (as carbon dioxide and biomass)
when the tequila vinasses are used.
Germán Buitrón (corresponding author)
Dorian Prato-Garcia
Axue Zhang
Laboratory for Research on Advanced Processes
for Water Treatment,
Unidad Académica Juriquilla,
Instituto de Ingeniería,
Universidad Nacional Autónoma de México,
Blvd. Juriquilla 3001,
Querétaro 76230,
México
E-mail: GbuitronM@ii.unam.mx
Key words | biohydrogen, continuous reactor, dark fermentation, fixed bed reactor, vinasses
INTRODUCTION
Vinasse is the dark-colored wastewater generated after the
distillation of ethanol that is produced during the fermenta-
tion of sugars. From 10 to 12 L of vinasses are generated as
residue per litre of tequila produced (Espinoza-Escalante
et al. ; Carvajal-Zarrabal et al. ). In 2013, there
were produced in Mexico about 226 × 10
6
L of tequila (CRT
). This residue poses a significant disposal and treatment
problem because of low pH (3–4), high temperature (70–
90
W
C), high biological oxygen demand (30–60 g/L), and the
presence of dissolved salts, melanoidins and polyphenolic
substances (Buitrón & Carvajal ; Carvajal-Zarrabal
et al. ). Therefore, researchers have been focusing on
improving the potential of biological treatment of this waste.
Sugarcane and tequila vinasse have been satisfactorily
treated by coagulation–flocculation, electrocoagulation,
anaerobic digestion and advanced oxidation processes
(Carvajal-Zarrabal et al. ; Zampol-Lazaro et al. ).
Anaerobic digestion is the most common method currently
applied in industrial scale. However, the high chemical
oxygen demand (COD) content in vinasses makes the
process inefficient and leads to a large amount of sludge.
In another common way, raw vinasse is applied as a fertili-
zer (fertirrigation) in sugarcane crops, which represents a
low-cost alternative to prevent the pollution of water
bodies. Fertirrigation has led to an increase of crop yield
and to reduction of the usage of chemical fertilizers. How-
ever, fertirrigation can cause salinization and soil erosion,
lixiviation of metals, alkalinity reduction, phyto toxicity
and unpleasant odor (Pant & Adholeya ; Christofoletti
et al. ). Moraes et al.() suggest that sugarcane
vinasse has great potential for energy production, but this
potential is wasted because of its application as a fertilizer.
The authors pointed out that the energy wasted by a sugar-
cane mill that uses fertirrigation as an alternative to treat
vinasse may be equivalent to the electricity demand of a
city of 130,000 inhabitants.
Biohydrogen is a promising fuel since it is considered as
clean, renewable, and high energy density (122 kJ/g) energy.
It has been illustrated that biohydrogen can be produced
efficiently from sugarcane vinasse, tequila vinasse,
1919 © IWA Publishing 2014 Water Science & Technology | 70.12 | 2014
doi: 10.2166/wst.2014.433