Iman Akbarpour,
Volume 4, Issue 1 (9-2023)
Abstract
On a global scale, the pulp and paper industry lead to produce significant amounts of effluents, solid wastes and gaseous wastes, and these wastes originate mainly from the pulping process, deinking and wastewater treatment. Solid biomass in wood waste as well as black liquor of pulping process can be converted to synthetic gas, mainly CO and H2 by thermal processes, with small amounts of methane, Co2 and H2o, and this can be a good opportunity to revive the pulp and paper industry. The main raw materials of biomass in the biorefinery process include hemicellulose, cellulose, lignin and skin, and with mechanical-thermal methods including biomass gasification, black liquor gasification, pyrolysis or liquefaction and carbonization of biomass, synthetic gas can be converted into electricity as well as liquid fuels and chemicals. The results obtained by comparing different hemicellulose pre-extraction technologies of lignocellulosic materials indicate that the steam explosion method is much more environmentally friendly than other alternative methods requiring less investment cost. At present, the use of steam explosion method has increased at the commercial level due to its cost-effectiveness and this method is very efficient for hardwood residues as well as crops leftovers. Also, the organosolve fractionation technology for the separation of hardwoods is well operational and leads to the production of high purity cellulose and the selective dissolution of lignin and hemicellulose. Nanofiltration is a desirable separation method for the recovery of hemicellulose from hydrolysates, and in this regard, the combination of a twin-screw extruder system can be the best way to extract hemicelluloses from hardwood chips. Nanofiltration is much better than ultrafiltration to separate hemicelluloses from hydrolysates by alkaline methods.
