Digestion of cattle manure: Thermogravimetric kinetic analysis for the evaluation of organic matter conversion

Anaerobic digestion of cattle manure was studied under thermophilic and mesophilic conditions with the purpose of evaluating the effect of temperature on the quality of the final digestate. Non-isothermal thermogravimetric kinetic analysis was applied for assessing organic matter conversion of biological stabilization. The mathematical approximation proves to be a useful tool for evaluating the differences attained during biological degradation. The anaerobic digestion of the organic substrate resulted in a reduction of the activation energy value obtained from the different applied kinetic models. Results obtained from thermal kinetic analysis were in accordance with those from the monitoring of the anaerobic digestion process. The higher values of methane yield reported for the mesophilic digestion in comparison to that of the thermophilic indicated a greater capability of the former process in the utilization of substrate and thus a higher conversion of organic matter which can be quantified by the activation energy value.