Characterization of Sewage Sludge for the Thermal Conversion into Gaseous and Liquid Energy Source

摘要

There have been various situation changes in Korea in the field of treatment of sewage sludge. They have mainly relied on ocean dumping for the final disposal of sewage sludge because the Korea peninsula is surrounded by sea. The international movement to ban ocean dumping and its increasing pressure to find alternative ways have made Korean government and industry look for in-land treatment methods. Our research group has focused on the utilization of heat content in sewage sludge after its physical drying process. We have done basic thermogravimetric analysis, finding that there exist unique mass reduction pattern of two stages. It was considered that there are two different major organic groups of intrinsic organic matter and polymeric fraction of higher boiling point. With a fluidized bed reactor, dried sewage sludge was gasified and quickly quenched to get liquid product at temperature range of 450-500 degree C. Almost 52% of liquid product could be obtained. By another reactor with temperatures of 500 degree C or higher, more product could be converted into gaseous phase at elevated temperature and it could be treated to be utilized in gas form. Various scale of systems are considered to get basic idea of converting the organic fraction of sewage sludge into clean energy source in actual application without generating secondary environmental pollution problems and without increased installation costs.