Advances in technologies for sewage sludge management

The chapter summarizes the existing technologies, providing a review both on the processes already applied at full-scale plants, and on the new processes that require further studies to be better understood. The technologies used to reduce sludge production can be applied at different WWTP locations. More precisely, in the water treatment line the action point is often the sludge recirculation line (from the secondary settler to the activated sludge reactor). In the sludge treatment line, the technologies can be applied at various points. Physical, chemical, and biological pretreatments can be performed before sludge digestion in view of improving the sludge characteristics. Advanced technologies such as thermal processes can be also adopted at the end of the sludge treatment line to recover heat, energy, and resources.