Experimental Study on the Characteristics of Sewage Sludge Pyrolysis Under The Low Temperature Conditions

Three sewage sludges with different diameters (1-0.5 mm, 0.5-0.2 mm and <= 0.2 mm) were pyrolyzed at laboratory scale, using a tube furnace under inert conditions to study the effects of temperature and diameter of sludge particles on the product yield distribution and composition. Upon comparing the yields of these sludges and analysis using GC-MS, it was found that a maximum of 32% oil yield was achieved at a pyrolysis temperature of 450 degrees C and particle diameter of 0.5-0.2 mm, and the maximum oils evolution rate is observed between the temperatures of 400-500 degrees C in all used sludges. These identified compounds in oils mainly consisted of aromatic rings linked by a branch chain and long straight hydrocarbon chains. The main compositions of the maximum ratio were C16H31N (Hexadecanenitrile) 12.49% in oil from 1-0.5 mm diameter particle, C16H32O3 (16-Hydroxyhexadecanoic acid) 7.53% from in oil 0.5-0.2 mm diameter particles, and C16H32O3 (16-Hydroxyhexadecanoic acid) 11.2% in oil from <= 0.2 mm diameter particles. Total ratios of aliphatic compounds were 12.41, 11.86, and 11.31% in sequence, respectively. Moreover, these oils contained low environmentally harmful compounds such as PAHs.