This handbook covers the most important basic principles of industrial wastewater treatment using activated sludge-based installations, oxidation beds (biofilters) and anaerobic wastewater treatment. The aim of this book is to teach or increase the basic knowledge that is necessary for the operation and management of (industrial) wastewater treatment plants (WWTPs) with focus on practical application. This book was prepared because, although there are many good technical manuals and theory books on wastewater treatment, most of these do not provide practical guidelines and background information that can be used in optimization, troubleshooting, and operating a biological wastewater treatment plant. This practical WWTP manual, developed by Cyprio, explicitly focuses on practical guidelines required for optimal process management of aerobic and anaerobic treatment plants. Whilst the necessary theory is also provided, the main aim of this book was to develop a training manual from practice for practice.