Saccharification of delignified sawdust from 20 different trees in the Lagos area of Nigeria

Abstract

Sawdust produced during the chopping of trees is a major waste product causing pollution of air as well as of the Lagos Lagoon in Nigeria. Sawdust from 20 different trees processed in the wood industry has been delignified successively by the Kraft process and hydrogen peroxide followed by Trichoderma viride cellulose catalyzed bioconversion into glucose, a fermentable sugar. Sugars are also released from sawdust during each delignification procedure prior to enzymatic catalyzed bioconversion. A 654% increase in sugar formation was observed from Entada gigas and 422% increase from Nauclea diderrichii when exposed to both delignification procedures compared to the amount of sugar released during Kraft pretreatment only. Relative high amounts of glucose were released during bioconversion of these waste celluloses when subjected to both delignification procedures compared to the bioconversion of Kraft delignified sawdust. Both delignification procedures resulted in a 175% increase in sugar formation for both Erythrophleum suaveolens and Milicia excels wood species. Different glucose concentrations were released during biodegradation with the highest at 9.23 mg.ml^-1 released from Lophira alata after Kraft pretreatment and 14.28 mg.ml^-1 from E. suaveolens after both delignification procedures. The concentration of sugar produced during the cellulase catalyzed bioconversion of delignified sawdust was many folds higher than the amount of sugars released during the delignification procedures.

Key words: Bioenergy, sawdust, Trichoderma viride cellulase, delignification, saccharification.