(587ae) Gasification Characteristics of Anaerobic Digestion Sludge and Aquatic Weeds

As preliminary experiments to examine optimum gasification condition of anaerobic digestion sludge and aquatic weeds, thermochemical gasification was carried out by changing gasification temperature and water vapor concentration. As samples, anaerobic digestion sludge which was generated by methane fermentation of food waste, Potamogeton maackianus and Elodea nuttallii (both were aquatic weeds) were used. As comparison, food waste and active sludge were also used.

In the experiment, samples were inserted into the electric furnace which was pre-heated to a desired temperature (873~1273 K), and then pyrolysis or steam gasification were performed under inert or steam containing atmosphere. At the exit of the furnace, all the effluent gases were collected to a gas bag, and the amount of the generated gases were measured using GC-TCD. As a result, high H₂ yield was observed from all samples under steam gasification condition compared to pyrolysis condition. This is probably due to the water-gas shift reaction by steam reforming. The gasification experiments at different temperature showed that with the increase of the temperature, the total amount of the produced gases were increased, however, calorific value of the gases peaked at 1173 K in some samples. The results indicated that even refractory organic compounds such as anaerobic digestion sludge and aquatic weeds, gasification characteristics were quite similar in the case of thermochemical gasification.