Horse manure as resource for biogas and nanolignocellulosic fibres.

This research focused on extracting nanolignocellulosic fibres (LCNFs) from horse manure via biogas production process, and studying its potential use in various applications due to its hydrophobic properties and strength.

Objective and Method

• The study aimed to develop a method to extract nanolignocellulosic fibres from horse manure during the process of biogas production to address the challenge with using nanofibrillated cellulose, which has a high affinity to water, weakening its structural integrity in certain applications.
• The researchers used horse manure as a source of organic matter for anaerobic digestion, from which biomethane is produced. In the process, lignin, an integral part of plant cell walls, is concentrated in the remaining fermentation residue. Lignin is a natural hydrophobiser, which means it repels water.

Results and Findings

• During anaerobic digestion of horse manure, a biogas yield of about 207 liters per kilogram was achieved, with a methane concentration of around 65%.
• The leftover fermentation residue contained nanolignocellulosic fibres (LCNFs) in yields of up to 41%, and the lignin content in these fibers ranged from 23 to 29wt% depending on the fermentation time.
• Upon experimentation, researchers found that nanopapers made from LCNFs boasted impressive tensile strengths and elasticity, between 45 to 91 MPa and 7 to 8 GPa respectively.
• The structural quality of LCNFs, as a result of increased lignin content, led to a decrease in the water absorption capacity of the produced nanopapers, addressing the original issue with nanofibrillated cellulose.

Implications and Conclusions

• The findings of this study imply that horse manure, a readily available waste material, can be resourcefully used for biogas production. In the process, high-quality LCNFs can be extracted, which could find potential applications in various fields such as composites, water filtration and as emulsifiers.
• Additionally, the decrease in water absorption capacity of LCNFs due to the inherent lignin content helps overcome a major challenge associated with use of NFC in certain applications, consequently expanding its versatility.