This book gives a detailed presentation of the theories behind modern wastewater treatment processes. It reflects the new theories for wastewater characterization, process description and modeling, which has been developed internationally during the last 10 years. The information intensity is unique due to the large amount of figures, tables and examples. Together with a detailed subject index, they help the reader understand the theories so that the book can serve at the same time as an advanced textbook for graduate students and a handbook for professionals. Consulting companies will find the book useful as a reference and standard for dealing with wastewater treatment processes at an advanced international level.