This book begins by providing information about wastewater treatment and its various application, especially in agriculture sectors. Some information about wastewater use and regulation in Saudi Arabia is also discussed. The main characteristics of the natural oxidizing pond system and the activated sludge procedure are described and their performance in the abatement of physico-chemical, bacteriological and virological pollution is discussed. Next, the authors describe and discuss the most common wastewater treatment processes and the importance of the activated sludge process in wastewater...