Thermo-gravimetric Analysis of Solid Fraction of Digestate Obtained by Rumen Fluid-Enhanced Anaerobic Co-Digestion of Sewage Sludge and Cattail

Abstract

In this study, thermo-gravimetric analysis (TGA) of the solid fraction of digestate from rumen fluid-enhanced anaerobic co-digestion of sewage sludge and cattail (grass Typha latifolia) was performed. TGA analysis was conducted under inert atmospheric conditions (100 mL N2/min) in the temperature range 25 – 800 °C at three different heating rates: 15, 50 and 100 °C/min. Proximate and ultimate analysis of tested samples was performed and the TG - DTG profiles (thermo-gravimetric profile and the profile of its first derivative) of digestate sample were compared to profiles of undigested sewage sludge and cattail. Kinetic analysis was performed using the Friedman kinetic model. The results show that anaerobic co-digestion significantly affects the characteristics of feedstock materials, as reflected in the TG and DTG curves. Estimated weight loss during pyrolysis was about 67.8 wt.% for sludge sample and 75.6 wt.% for cattail sample at heating rate of 15 °C/min. Weight loss of digested samples was lower: 55 wt.% on average. Kinetic analysis shows that the digested mixture could be promising feedstock for the pyrolysis.