Evaluation of First-Order,Second-Order,and Surface-Limiting Reactions in Anaerobic Hydrolysis of Cattle Manure

Three kinetic models were evaluated in this study for suitability in describing anaerobic hydrolysis of particulate wastes. The three models evaluated were: first-order reaction in particulate substrate concentration, second-order reaction in acidogenic biomass and particulate substrate concentrations, and a two-parameter, surface-limiting reaction model. Process models incorporating the three hydrolysis reaction models were developed to describe the hydrolysis-acidogenesis phase in the fermentation of cattle manure. Batch reactors were run with cattle manure as the substrate under five different conditions to calibrate and validate the process models. The two-parameter, surface-limiting reaction model and the single-parameter, second-order reaction model were found to fit the experimental results better than the simple first-order reaction model with r ² values of 0.914, 0.913, and 0.881, respectively.