This lesson is the second of a two-part series on anaerobic digestion. Topics discussed include classification of digester by function, roof design, and temperature range, mixing systems, gas system components, operational control basics, and general safety considerations. The lesson includes an instructor's guide and student workbook. The instructor's guide contains a description of the lesson, estimated presentation time, instructional materials list, suggested sequence of presentation, reading lists, objectives, lecture outline, narrative of the slide/tape program used with the lesson, references, and student worksheet (with answers). The student workbook contains plant flow diagrams, objectives, glossary, discussion material, references, and worksheet. Discussion material is presented in seven sections titled: digester classification (tanks), boilers and heat exchangers, mixing systems, gas system, operational control, sampling and testing, and safety. (JN)