Biogas production potential from switch grass-animal manure mixture using dry anaerobic digestion

摘要

Anaerobic digestion is a biological method used to convert organic wastes into a stable product for land application without adverse environmental effects. The biogas produced can be used as an alternative renewable energy source. Dry anaerobic digestion (> 15% TS: total solid) has an advantage over wet digestion (<10% TS) because it allows for the use of a smaller volume of reactor and because it reduces wastewater production. In addition, it produces a fertilizer that is easier to transport. Performances of anaerobic digestion of animal manure-switchgrass mixture were evaluated under dry (15% TS) and thermophilic conditions (55 deg C). Three different mixtures of animal manure (swine manure, poultry manure, and dairy manure) and switchgrass were digested using batch-operated 1-L reactors. Swine manure test unit showed 58% VS removal during 30 day trial while dairy and poultry manure test units showed 24% and 31%, respectively. Over the 30 day digestion, the swine manure test unit yielded the highest amount of methane yield 0.229 L CH_4/g VS, while, the dairy and poultry manure test units showed very poor methane yield 0.009 L CH4 /g VS and 0.002 L CH_4/g VS, respectively. These results indicate that the swine manure test unit has the highest biogas production potential among the three different types of animal manure.