Thermal Destruction of Biological Sludge in a Rotary Kiln

Although the destruction of biological sludge in multiple hearth and fluid bed cumbustors is well demonstrated, both technologies can be problematic. The multiple hearth often cannot meet the strict emission guidelines of RCRA due to the counter current nature of the process, and the fluid bed can experience problems with low melting eutectics when the salt content in the sludge is very high. Combustion of sludge in the rotary kiln can overcome both these obstacles. In a four foot diameter by fifteen foot long rotary kiln, biological sludge was successfully combusted. A destruction removal efficiency of 99.999% was achieved using carbon tetrachloride and chloroform as the principle organic constitiuents. Details of how the demonstration tests were performed as well as some of the inherent difficulties of sludge combustion in a rotary kiln are presented.