Sewage can be cleaned near the sewage treatment plant, which can be called a “separation” system or a “local” system (sewage treatment center, septic tanks, etc.). Alternatively, sewage can be collected and transported through a network of pipelines and pumping stations to the municipal treatment plant. This is called a “medium” system.

A large number of sewage treatment technologies have been developed, mainly using biological treatment procedures. For the most part, they can be categorized into high technology and low technology options based upon the cost involved. Some categorizations are “deep” or “mechanical” systems (highly integrated, and often use high-tech options) against “broad” or “natural” or “environmental-based” systems (usually using natural therapies and large-scale residential) systems. . This separation can sometimes be made much easier, because the medicinal plant may incorporate a combination of processes, and the definition of high-tech and low-tech, deep and comprehensive, mechanical and environmental processes may vary from place to place