Sewage sludge
（重定向自Biosolid）
![Sludge](/Images/godic/202412/24/Sludge5245.jpg")
![Desiccation cracks in dried sludge, the hard final remains from a sewage plant.](/Images/godic/202412/24/Desiccation-cracks_hg5245.jpg")
Sewage sludge refers to the residual, semi-solid material that is produced as a by-product during sewage treatment of industrial or municipal wastewater. The term septage is also referring to sludge from simple wastewater treatment but is connected to simple on-site sanitation systems, such as septic tanks.