Abstract: A process is described for treating waste organic material such as the by-products from a pulp and paper mill, manure and straw to reduce its moisture content to a level at which the treated material is suitable for use as a fuel. The process involves the steps of feeding the starting material into a chamber (10) having rotating chains (42) or blades which drive the material into the interior wall (18) of the chamber (10) with sufficient force to cause some of its moisture content to separate from it. The moisture is expelled from the chamber (10) while the remaining material is carried upwardly in a stream of air to a cyclone separator (22). The conditions within the separator (22) are adjusted to further reduce its moisture level to about 15 percent by weight at which level the material is suitable for use as a fuel.