Municipal sludge has energy content in the range of (9,000-23,000 kJ/kg) depending upon the organic content. This entrapped energy can be transformed into heat and electrical energies by different technologies combining biological and thermal processes. Recently, the combination of advanced digestion and incineration or gasification was found to be advantageous for energy recovery. The energy balance was based upon a full-scale wastewater treatment plant (WWTP) using conventional and advanced treatment configurations. In this respect, the unit electricity production from sludge was calculated to be in the range of 675-1,240 kWhE per tones of dry solids.