The Effect of Distinct Operational Conditions on Organic Material Removal and Biogas Production in the Anaerobic Treatment of Cattle Manure

Abstract

Although very difficult to treat due to their complicated composition, the increasing amounts of cattle manure generation makes their purification a compulsory task for environmental engineers to prevent their adverse environmental impacts. Historically, these wastes have been used as a fuel or a soil fertilizer. The generation of cattle manure even in increasing amounts in Turkey, however, makes this kind of use unfeasible. Therefore, new methods to dispose of these wastes are required. This study focuses on the anaerobic digestion process for the treatment of cattle manure. In the study, two lab-scale anaerobic reactors were employed to investigate the effects of different operating temperatures (35 oC and 55 oC), of different total suspended solids concentrations (%5 and 10%), of different hydraulic retention times (20 days and 40 days), and of the addition of corn silage on the treatment performance. The performance of the reactor was evaluated with respect to total solids (TS), volatile solids (VS) and biogas production. The results of the study suggested that the thermophilic reactor showed a good treatment performance (59% VS removal and 0.29 L methane per VS added) when the cattle manure of 10% solids content together with corn silage were fed. Besides, it was concluded that the addition of corn silage to the reactors improved the treatment efficiencies and that the addition of irrigational organic materials increases biogas production rate. The results of the study point out that anaerobic digestion process is a viable option for cattle manure stabilization and valuable gas production.