During anaerobic digestion of organic waste, such as in producing...

During bio-gas formation, digestion of cellulose is slow (ratc-limiting) and most of the lignin Is not decomposed. Lignin is a complex polymeric molecule, made up of phenyl propanoid units. This complexity has thus far proven as resistant to microbial degradation. After cellulose lignin is the most abundant plant polymer. It forms 20 to $30 \%$ of the wood of the tree. Cellulose is a large chained polymer of glucose molecules which are linked with each other by glycosidic bonds. Hemicellulose are branched polymers of glucose, xylose, galactose, mannose and arabinose.