USE OF FLOCCULANTS TO AID THE DEWATERING OF PEAT

Ohinewai peat (Waikato River Valley, New Zealand) has been treated with various flocculating reagents, and the extent of flocculation has been assessed by measurements of electrophoretic mobility, specific resistance to filtration, and coefficient of compressibility of the filter cake. Of several commercial polyelectrolytes studied, Zetag 87, a highly cationic flocculant of medium molecular weight, was the most effective. Treatment with this or similar flocculants, followed by filtration under slight suction, was found to remove more than 50% of the original moisture from the peat. Such a process could be useful for preparing fuel peat in cooler climates where solar drying was not feasible. However, to be economical, the process would require a less expensive flocculant. In warmer climates where solar drying was feasible, an alternative and cheaper process using a non-ionic flocculant (Magnafloc 351) is described. © 1990.