Production of Bio-Methane and Beyond

E verybody enjoys fresh, nutritious eggs, especially at breakfast, but consumers typically ignore the ugly, smelly byproduct of egg production, chicken manure. An average sized egg farm keeps about a million laying hens, or layers. One million layers produce approximately 100 tons of fresh manure every day. Even small farms with 100,000 birds have to handle about 10 tons of manure every day. Waste management is a big challenge for animal farmers. When I came to North Carolina State University (NCSU) in 1976, with background training in microbiology and biochem-istry, I was asked to develop a process to manage and utilize this byproduct. e process that I chose to study is called anaerobic digestion. In the absence of oxygen, organic matter can be degraded by a host of bacteria that anaerobically break it down to organic acids and alcohols and then convert these into CO2 and methane. Hundreds of kinds of these bacteria can be divided into three groups, 1) the hydrolytic group, 2) the acetogenic group, and, 3) the methanogens. e hydrolytic group converts complex poly-mers to simple monomers. e acetogenic group converts fatty acids into acetic acid, CO2, and hydrogen. e methanogen