Syngas generation from different types of sewage sludge using microwave-assisted pyrolysis with silicon carbide as the absorbent

In this study, the pyrolysis of sewage sludge was explored through microwave-assisted pyrolysis. Three kinds of sludge (primary sludge, waste-activated sludge, and digested sludge) from a sewage treatment process were used. All three kinds of sewage sludge had a low microwave absorption capacity; therefore, an absorber was added to enable microwave-assisted pyrolysis. By using silicon carbide as the heating element, it was possible to increase the temperature within a short time by applying microwaves. During the microwave-assisted pyrolysis of sewage sludges, the amount of gas generated and the H2 and CO fraction of the produced gas increased as tem-perature increased. The pyrolysis of waste-activated sludge produced the greatest quantity of gas. However, the primary sludge produced the highest amount of syngas in terms of H2 and CO, which indicate the high-quality of the syngas.