Achievement of Iranian researchers
Enhancing ethanol and methane production from rice straw by pretreatment with liquid waste from biogas plant
In a recent study at Isfahan university of technology rice straw was introduced into the bio-ethanol and biogas production process at different temperatures and times.
Among the various biofuels, biogas is a major green fuel, especially in rural areas. Biogas is produced through microbial decomposition of organic matter under oxygen-free conditions.
Bioethanol, the most important liquid biofuel, is widely used as a fuel or gasoline enhancer worldwide. The high oxygen content of ethanol as an oxygenate liquid decreases the amount of required additive, causes better combustion of hydrocarbons and reduces the emissions of aromatic compounds and CO.
According to the total solid content, anaerobic digestion (AD) plants can be classiﬁed into dry AD(D-AD) and liquid AD(L-AD).
Diﬀerent renewable substrates can be used for biogas and bioethanol production. The main goal of the lignocelluloses pretreatment is to change different compositional and structural properties of biomass, aiming at enhancing bioenergy production. In a recent study at Isfahan university of technology rice straw was introduced into the bio-ethanol and biogas production process at different temperatures and times. Structural changes of rice straw were investigated by FTIR, SEM analysis.
“Rice is the main feed of people in our country.” Says Dr. Karimi, Associate Professor in Isfahan University of Technology and the team leader in this study
“Almost a kilogram of rice straw is produced per kilogram of rice. Therefore, it is important to find a suitable solution for using rice straw produced after harvesting rice. Energy production in the form of biomass and bioethanol is a suitable solution for energy recovery from rice straw. On the other hand, the disposal of liquid waste from the process of anaerobic treatment plants also has many environmental problems. Therefore, in this research, we tried to use this liquid for the pretreatment of rice straw.”
This study investigated the possibility of using the biogas liquid waste for the pretreatment of rice straw at various conditions. The pretreatment at 130, 160, and 190°C for 30 and 60min with this waste stream increased the enzymatic hydrolysis yield of straw from 38% to 76%. Furthermore, ethanol yield was enhanced over two-fold after the treatment. Improvement in methane production via L-AD and D-AD was 24% and 26%, respectively.
Results of this research has been published recently in the peer reviewed journal Energy conversion and management.