Green Fuel from Sewage Sludge

Abstract

The Sewage Sludge (SS) generation rate is continuously increasing globally due to the population growth, enlargement of wastewater treatment facilities, and application of stringent wastewater treatment directives. A promising strategy is energy recovery from SS by anaerobic digestion, for the management of SS over the practiced route of agricultural reuse, landfilling, and incineration in terms of greenhouse gas emission reduction and increase of renewable energy production with higher efficiency. SS could be considered a potential source of renewable energy. Therefore, green energy from SS through anaerobic digestion may contribute to increasing the renewable energy share of the world’s primary energy consumption. The scenario on the SS generation system and its quantity in different regions of the world with management strategies and environmental problems are presented in this chapter. The chapter also shows the variation of SS composition in different countries. Energy recovery from SS as biogas through anaerobic digestion consists of four steps: hydrolysis, acidogenesis, acetogenesis, and finally, methanogenesis. Strategies and operating conditions, for different bacteria and archaea involved in four steps, to maximize the efficiency of the digestion process of SS are presented in this chapter. The impact of antimicrobial agents in SS and operating parameters on the efficiency of biogas conversion and quality are discussed. Application of biogas in electricity and heat generation, combined heat and power generation, biomethane production, hydrogen generation, and in the fuel cell are presented. Finally, recommendations are proposed to improve the digestion performance, in terms of biogas quality and conversion efficiency.