Separation and utilization of pulp and paper process residuals

Pulp and paper process residuals are primarily made up of lignin, cellulose and semicellulose. In this study we attempted to apply environmentally friendly and economically feasible technologies to separate and utilize those components for beneficial purposes. Biological acid precipitation was shown to be suitable for the separation of lignin from the process wastewater. In the case of cellulose and semicellulose, bioconversion was explored to produce fuel ethanol using simultaneous saccharification and cofermentation (SSCF). The organic acids (mainly citric acid and acetic acid) produced from Saccharomycopsis Lipolytic can be achieved at the lowest pH (3.6) and in this situation the maximum lignin precipitation (78.6%) occurred. Biological acid precipitation also leads to good removal of COD and color, reaching 87.6% and 68.4%, respectively. Bioconversion of pulp and paper sludge by SSCF resulted in maximum ethanol concentration of 5.69g/L using mixed cultures of Saccharomyces cerevisiae and Escherichia coli KO11.