The report highlights various types of SBRs, design considerations and procedures, equipment required, and experiences gained from practical applications. This report will help both designers and operators of SBRs understand how to use this technology successfully. The focus is on the application of fill-and-draw, variable volume, periodically operated, unsteady-state principles to activated sludge systems. Research findings are presented, from both the laboratory and pilot and full scale SBRs. Also included is a description of trends for technological developments and a discussion of open questions regarding research, development, application, and operation. Contents Introduction Fundamentals of Periodic Processes General Overview of SBR Applications Design of Activated Sludge SBR Plants Equipment and Instrumentation Practical Experiences Evaluation of SBR Facilities in Australia Evaluation of SBR Facilities in the USA and Canada Evaluation of SBR Facilities in Germany Evaluation of SBR Facilities in France Evaluation of SBR facilities in Japan Scientific and Technical Report No. 10