ARS | Publication request: The Effect of Enzyme Addition on Anaerobic Digestion of Jose Tall Wheat Grass

Submitted to: Bioresource Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 25, 2008
Publication Date: May 24, 2009
Citation: Romano, R.T., Zhang, R., Teter, S., Mcgarvey, J.A. 2009. The Effect of Enzyme Addition on Anaerobic Digestion of Jose Tall Wheat Grass. Bioresource Technology. 100(20):4564-4571.

Interpretive Summary: Enzymes are biological catalysts that enhance the digestion of several types of materials. We studied the use of 3 types of enzymes to aid in the breakdown of agricultural waste. Our findings showed that the enzymes were able to degrade the waste, but did not result in significant improvements when added to anaerobic digesters. We hypothesized that the bacterial flora within the digesters was able to produce all of the necessary enzymes and that exogenous enzyme addition is not necessary.

Technical Abstract: The effects of the addition of enzyme products containing cellulase, hemicellulase, and Beta-glucosidase to anaerobic digestion systems were studied. Anaerobic digestion tests were performed using batch reactors operated at 35°C. The application of enzyme products in three digestion configurations were investigated: (1) enzyme addition to a single-stage digester, (2) pretreatment of waste with enzymes followed by anaerobic digestion, and (3) enzyme addition to the first stage (hydrolysis and acidification) of a two-stage digestion system. The enzyme products showed positive effects on the solubilization of waste when used alone. However, no significant differences in biogas and methane yields, and volatile solids reduction resulted when the enzyme products were tested in anaerobic digestion systems. This reveals that the microorganisms present in the innoculum were effective in carrying out the digestion process. The types of microorganisms were identified using 16S rRNA sequence analysis.