This new book on membrane bioreactors (MBRs) aims to provide basic information for teaching, practical material for practitioners and sufficient depth for researchers. It successfully achieves these aims. The book provides a very comprehensive coverage of MBRs with 13 chapters authored by specialists in various aspects of the technology. This book is indeed a magnum opus – very comprehensive and a great source of information. Each chapter has an extensive reference list. Another valuable feature is that each chapter has a final ‘Future Outlook’ that speculates on the future trends and developments relevant to that chapter. This book is a major effort by a large team of MBR experts; many names will be familiar to those working in the field. I recommend it to anyone or any organization interested in the remarkable technology we call ‘the MBR’.