EFFECT OF PREDRYING ON THE PORE STRUCTURE DEVELOPMENT OF SEWAGE-SLUDGE DURING PYROLYSIS

Pyrolysis of digested sewage sludge was conducted in a nitrogen atmosp here in this study. The effects of temperature and air pre-drying on t he surface area and pore structure development were investigated. It i s found that the BET surface area of the chars derived increases with increasing temperature. Pre-dried sewage sludge results in higher surf ace area in the char than the raw sludge. It is demonstrated that pre- drying has an effect of promoting micropore structure development, whe reas there are more mesopores and macropores developed in the raw slud ge char due to possible pore enlargement resulting from volatile gas b ubbling out of the softened intermediate product during pyrolysis in t he temperature range of 550-degrees-C - 650-degrees-C.