This Manual provides information for designers, builders and operators about a wide range of applications and objectives such as developing, implementing and operating Artificially Constructed Wetlands (ACW) and Waste Stabilization Ponds (WSP)||Standard systems approach which can be adopted universally and which can accommodate a development technology with changes in information concepts and ideas with time||theoretical background on the biological, chemical and physical processes of each method, the current state of the technology and technical knowledge on how to design, operate and maintain them||and theoretical knowledge on how best the models may be used to describe the systems.