Due to the advanced treatment of the applied wastewater, simplicity of operation, and the economical attractiveness and low cost maintenance SAT systems are now widely used method for combined groundwater recharge and wastewater treatment. However, the knowledge of the environmental biochemical transformation is fundamental in understanding and predicting the fate of nitrogen and organics in soil and groundwater. This book, therefore, provides the basic concepts of SAT method and applies them to the operation and management of the system. Chapters cover the background information useful to those new to the SAT systems, including the chemistry of nitrogen and organics in the unsaturated soils. Advanced discussion also extends to simulating the fate of nitrogen in soil under different operation scenarios of SAT, and in making sound decisions about management of the system.