EFFICIENT DRYING OF SLUDGES

Discharges of chlorinated organic compounds from bleached kraft pulp m ills are expected to be limited to 1.5 kg AOX/ton in the near future. Some of the chlorinated organics not eliminated through process modifi cations could be ''trapped'' on sludge from the external treatment pro cess(es). The disposal of pulp and paper mill sludges, which may conta in chlorinated organic compounds, represents an increasing problem. Ho wever, if these sludges could be dried to 90% dry content in an energy -efficient manner, they could provide sufficiently high flame temperat ures upon combustion to destroy the organic chlorides entrapped in the sludges. In addition, this approach could improve a mill's fuel self- sufficiency. A novel drying method, based on the Carver-Greenfield pro cess for pulp and paper mill sludges investigated at Paprican, indicat ed the potential to provide the above dryness criterion, with possible advantages over existing drying technologies.