TITLE:
Rheological Characterization of a Mixed Fruit/Vegetable Puree Feedstock for Hydrogen Production by Dark Fermentation
AUTHORS:
Jacob Gomez-Romero, Inés Garcia-Peña, Jorge Ramirez-Muñoz, Luis G. Torres
KEYWORDS:
Bio-Hydrogen; Mixing; Rheology; Rheofluidizing Materials; Fruit/Vegetable Waste Mixture
JOURNAL NAME:
Advances in Chemical Engineering and Science,
Vol.4 No.1,
January
27,
2014
ABSTRACT: Bio-hydrogen (Bio-H2) production from the
organic fraction of solid waste, as fruit and vegetable wastes, constitutes an
interesting and feasible technology to obtain clean energy. In spite of the
feasibility to produce Bio-H2 from fruit/vegetable wastes (FVW),
data about its rheological characterization are scarce. This
information is useful to establish the hydrodynamic behavior, which controls
the overall mixing process when the feedstock for Bio-H2 production
process is a mixture of FVW. In this work, the rheological
behavior of a vegetable/fruit waste mixture was characterized. The effect of
the solids content (%, w/w), temperature, time (tyxotropy effects) and shear
rate over the apparent viscosity of the mixture was evaluated. Most of the
mixtures showed non-Newtonian behavior. The curves are typical rheofluidizing
fluids. The rheological curves were different at increasing solids contents (80%, 60%, 40% and
30%), independent from the temperature. Rheological data were fitted to
the power law model. Correlation factors R2 for the different mixtures were
0.991-0.995 for 80%, 0.961 -0.986 for 60%, 0.890 -0.925 for 40%. In
the case of 30% of solids, the R2 value was not acceptable, and it
was also found that this mixture was very near to the Newtonian behavior.
Calculated activation energies (Ea) values were 15.98, 14.89 and 20.96 kJ/mol
for the 80%, 60%, 40% mixtures, respectively. FVW purees rheological behavior was
well characterized by Carbopol solutions at given concentrations and pH values.
This fluid can be used as a model for other studies, e.g. LDA (Laser Doppler
Anemometry) and PIV (Particle Image Velocimetry).