The Impact of Selected Sewage Treatment Methods on the Change in Parameters of Sewage Sludge Originating from Municipal Sewage Treatment Plants

Sewage sludge is produced in every sewage treatment plant and its properties depend on a number of factors. The type, origin and parameters of the treated sewage and the applied treatment technology are the main factors influencing the sludge properties. The produced sewage sludge can be submitted to treatment processes which condition its final use. For example, the sludge produced in small treatment plants, treating mainly domestic sewage, can be used for agricultural purposes. This paper presents the results of the authors' own research on the susceptibility of sludge originating from several municipal wastewater treatment plants to selected treatment processes and changes in properties as a result of the carried out processes. The obtained results confirm that the ultrasonic field, as a physical method of sewage sludge modification, is a factor intensifying the drainage processes. In most cases, the investigations have shown better results of the dewaterability of sludge treated with ultrasonic field in relation to raw sediments. For the tested sediments, it is justified to use the centrifugation process as a method of mechanical compaction.