There are several types of sewage treatment plants, including Conventional Activated Sludge Plants (CASP), Sequential Batch Reactors (SBR), Extended Aeration Systems, Rotating Biological Contactor (RBC), Membrane Bioreactor (MBR), Trickling Filter System, and Constructed Wetlands. The choice of STP depends on factors such as treatment scale, wastewater characteristics, and available resources.