Sludge obtained from the biological wastewater treatment facility of a chemical plant was pyrolyzed for reuse via microwave heating in the temperature range of 400–800 °C. Higher temperature reduces the yield of residues and enhances the gas production. The pyrolysis process produced 16–24 dry-wt.% of oil, which the heat value ranged from 7600 to 8300 kcal kg?1. Apart from As, Cd and Mo, merely a small amount of toxic elements can be released into pyrolysis oil. For the liquid oil, the total concentration of the 16 PAHs was 100–207 μg g?1 and the concentration of nitro-PAHs is much lower than that of PAHs. High temperature increases the energy consumption in microwave power and reduces the produced energy from pyrolysis residue and oil. Therefore, lower energy consumption and higher energy recovery efficiency could be achieved at lower pyrolysis temperature.