Abstract: Bulk tree bark removed as a preparatory procedure to pulping wood for use in the paper industry is converted into a useful humus by-product through the use of a system and method wherein the bark is delivered to a receiving station in an aerobicly untreated state. This material then is adjusted to optimize the nitrogen content thereof through the addition of nitrogenous material. Additionally the pH level thereof as well as the moisture level is optimized through the utilization of a mixing arrangement which agitates and retains the materials over a predetermined time interval. The material then is transferred to a digester apparatus where it undergoes aerobic thermophilic phase digestion under the influence of induced atmospheric air and agitation. Two digester arrangements are described.

Abstract: System and apparatus for treating organic waste material, suited, for example, for the aerobic-thermophilic treatment of cattle manure. The waste material initially is commingled with an expanded, size limited dry cellulosic material in a mixing stage, preferably, a pug mill device, to achieve a bulk density and moisture content optimized for thermophilic digestion. A digestion arrangement is provided assuming a reliability for complete aerobic treatment of all material removed therefrom.