Common Reed and Maize Silage Co-Digestion as a Pathway towards Sustainable Biogas Production

Abstract

The key factor in sustainable biogas production is a feedstock whose production has no adverse impact on the environment. Since maize cultivation harms the environment, biogas plant operators seek a more sustainable feedstock. Common reed is an invasive species mown as part of wetland conservation measures, or it can be harvested from paludiculture. This study aimed to investigate wet co-digestion of maize silage with 10%, 30%, and 50% content of common reed silage using the biochemical methane potential (BMP) test. In addition, the potential energy generated and avoided greenhouse gas (GHG) emissions were calculated. The substitution of maize silage with 10%, 30%, and 50% content of reed silage reduced the methane (CH4) yield by 13%, 28%, and 35%, respectively. A disadvantage of reed silage addition was increased ammonia (NH3) and hydrogen sulfide (H2S) concentrations in biogas. Although substituting maize silage with reed silage decreases the CH4 yield, the co-digestion of maize and reed biomass from conservation or paludiculture may positively affect environmental aspects of energy generation. The substitution of maize with reed in biogas plants decreases the area used for maize cultivation and reduces GHG emissions.