the properties of raw sludge. Parallel to the characterization of the sludges runs characterization of the sludge treatment-processes and the environment in which we dispose of the sludge. In the following discussion we will group parameters related to sludges into three cathegories: 1. Sludge Quantity. Both total ~nd per capita sludge production data from all connnon sewage and sludge treatment methods are of "interest. 2. Treatability parameters. These are characteristics of how a sludge behaves in a specific process. Typically; dewaterability and digesta­ bility. 3. Sludge quality parameters. These are indicators of how the sludge could influence the environment when disposed of. Sludge quality changes through most sludge treatment processes (stabilization, ther­ mal etc.) and include concentrations of chemical compounds, pathogenes etc.