Co-fermentation of macroalga Elodea canadensis in different mixing ratios with dairy manure

Abstract

Dairy manure is a valuable by-product of the animal production industry, but it may cause environmental problems due to inappropriate management and utilization. Although Elodea canadensis is an invasive species, it can be used as a renewable energy source for production of some biorefinery products such as biogas. Therefore, the potential use of E. canadensis biomass as a co-substrate for biogas generation was investigated by gradually increasing the amount of E. canadensis in the mixture containing dairy manure. Microalgae collected directly from Lake Egirdir by hand were first dried and then subjected to grinding. Five different mixtures were prepared for the co-fermentation of E. canadensis with dairy manure. The experiments were carried out in the anaerobic digester unit, which consists of 2-L bottles in a temperature-controlled water bath. The results showed that the specific methane production of the mixture containing only dairy manure was 192.3 mL CH4/g OM, while that of the mixture containing only E. canadensis was measured as 151.1 mL/g OM. As a result, the increase in the amount of E. canadensis in the mixture decreased biogas and CH4 production. However, this study showed that it is possible to produce biogas from E. canadensis, and an undesirable invasive species in natural water resources can be used as a biomass energy source.