Biological Systems Engineering


Date of this Version



Published by University of Nebraska – Lincoln’s Livestock Environmental Issues Committee.


What is an Anaerobic Digester?

The first methane digester plant was built at a leper colony in Bombay, India in 1859. A methane digester system, commonly referred to as an AD (anaerobic digester) is a device that promotes the decomposition of manure or “digestion” of the organics in manure to simple organics and gaseous biogas products. Manure is regularly put into the digester after which the microbes break down the manure into biogas and a digested solid. The digested manure is then deposited into a storage structure. The biogas can be used in an engine generator or burned in a hot water heater modified for biogas. AD systems (Figure 1) are simple biological systems and must be kept at an operating temperature of 100 degrees F in order to function properly.