Anaerobic technology has become widely accepted by the environmental industry as a cost-effective alternative to the conventional aerobic process. In addition, with the intrinsic advantages of energy saving, reduced sludge yield, and production of biofuel, anaerobic process will be the favored green treatment technology for sustainable environment in years to come. Written by 40 renowned experts from 13 countries/regions, this book consists of 18 chapters compiling state-of-the-art information on new developments in various aspects of anaerobic technology. These include development of new types of reactors, uses of molecular techniques for microbial studies and mathematical modeling, productions of bio-hydrogen by fermentation and microbial electrolysis cell, as well as broadening applications to the treatment of municipal wastewater, effluents from chemical industry and agricultural wastes with high lignocellulose content.