Unit 3.1: Introduction


All anaerobic digesters perform the same basic function.  They hold organic matter in the absence of oxygen and maintain the proper conditions for methane forming microorganisms to grow.  There are a wide variety of anaerobic digesters, each performing this basic function in a subtly different way.  Eight of the most common digesters are described in this module. Construction and material handling techniques can vary greatly within the main categories. For clarity, digesters are divided into three categories — passive systems, low rate systems, and high rate systems. We will also look at the special case of high solids digestion.