This book covers the treatment of wastewater by anaerobic process. Fundamentals of anaerobic processes, microbiology process, and environmental and operational factors affecting anaerobic digestion are discussed. Furthermore, importance is given on the existing anaerobic treatment of wastewater and treatment of pharmaceutical by anaerobic stage reactor. The book focuses on reactor performance in terms of organic pollutant removal efficiencies, volatile fatty acids and methane production profile in the reactor system. The microbiology aspects of anaerobic sludge in the stage reactor were also discussed in detail to give insight into the bacterial activity. Bacterial population in anaerobic stage reactor, and comparison between archaeal and bacterial populations in each stage of the reactor by means of fluorescent technique are given. Some of the main possible combination's of anaerobic reactors with post treatment systems as well as control of anaerobic reactors were discussed. 
    This book is essential for undergraduate and postgraduate students to enhance their knowledge on anaerobic treatment systems and operating procedures. For practitioners, this book gives thoughtful knowledge on anaerobic digestion and operation of anaerobic reactors..