Author(s)

Carlos Rico, Rubén Diego, Agustín Valcarce, José Luis Rico

Department of Chemical and Process Engineering Resources, University of Cantabria, Santander, Spain.
Department of Water and Environment Science and Technologies, University of Cantabria, Santander, Spain.
Teican Medioambiental, Boo de Piélagos, Cantabria, Spain.

Batch trials were carried out to determine the methane potential yields of some typical organic wastes generated in the region of Cantabria (Spain): cocoa shell, cheese whey and sludges from dairy industry. Anaerobic co-digestion trials of these wastes with dairy manure were also investigated in batch at 35℃. Cheese whey obtained similar methane yields than dairy manure, between 17.5 and 19.3 L CH4kg^-1 cheese whey compared with 18.0 L CH4kg^-1 manure. Methane yields of various sludge samples collected from wastewater treatment facilities of dairy industries were influenced by its origin. Sludge samples from fat separation devices were the most productive in terms of specific methane yields compared with biological sludge from an aerobic reactor. Sludge samples from fat separator reached specific methane productivities of 350 and 388 L CH4kg^-1 VS (10.5 and 24.1 L CH4kg^-1 sludge), whereas biological sludge yielded 125 L CH4kg^-1 VS (12.6 L CH4kg^-1 sludge). The methane potential of sludge samples was influenced by solids content. Cocoa shell resulted to be an interesting waste for anaerobic digestion due to its high VS content, yielding 195 L CH4kg^-1 cocoa shell. It is a waste that can considerably improve methane yields in anaerobic co-digestion with dairy manure. However, at proportions of 10% cocoa shell, the process was hindered by hydrolysis of particulate matter. Anaerobic digestion at higher temperatures (thermophilic range) could be a better option for this kind of waste. Co-digestion of 5% cocoa shell with 35% dairy sludge and 60% dairy manure resulted in 80.5% higher methane production compared to anaerobic digestion of dairy manure alone.

Cheese Whey, Co-Digestion, Cocoa Shell, Dairy Sludge, Manure

Rico, C. , Diego, R. , Valcarce, A. and Rico, J. (2014) Biogas Production from Various Typical Organic Wastes Generated in the Region of Cantabria (Spain): Methane Yields and Co-Digestion Tests. Smart Grid and Renewable Energy, 5, 128-136. doi: 10.4236/sgre.2014.56012.