Anaerobic Digestion, Important Aspects Regarding Digester Design and Sludge Mixing Systems

Anaerobic sludge digestion is a natural process in which bacteria decompose organic material, whereby the sludge is stabilized and at the same time, biogas is produced. Owing to sludge stabilization, the sludge volume is reduced and with it, the carbon footprint of the used water treatment plant and transportation costs. This process is highly complex and sensitive and takes place in anaerobic digesters. Anaerobic digesters have been used for decades at municipal used water facilities and are designed to maximize the degradation of organic matter and optimize the growth of the bacteria that generate methane. There are many differing digester shapes and mixing possibilities, but irrespective of the design employed, several operating conditions must exist in order that optimum organic material degradation is attained. For this reason, anaerobic processes, digester design, and digester mixing are closely connected and an understanding of these relationships is very important when choosing and setting up a system.