Upgrading waste whitewater fines from a pinus radiata thermomechanical pulping mill

The pulp and paper industry is very efficient in utilizing its wood resource. However, due to the large amounts of resource used, waste from pulp and paper industry is significant in both its quantity and the opportunities it provides. However, fibrous waste has typically only been used for heat recovery, direct land application or separated and sent to landfill. In this study, two options were investigated for utilising fine fibrous waste recovered by Dissolved Air Flotation (DAF) treatment of effluent from a thermomechanical pulping mill. 3000 kWh/t of mechanical treatment of the waste fibres increased the sheet strength from 28 Nm/g to 40.5 Nm/g, which is high enough to reuse these fibres within the mill by recycling them back into the main process stream. Additional high-pressure homogenization is capable of producing hydrophobic nanoscale (10 20 nm) fibrils, which could be used in special applications such as bio-nano-composites with non-polar matrices.