Sewage sludge pyrolysis for liquid production: A review

Sewage Sludge Pyrolysis for Liquid Production: A Review

Authors: Isabel Fonts, Gloria Gea, Manuel Azuara, Javier Ábrego, Jesús Arauzo

Field: Renewable and Sustainable Energy Reviews

Document Content: This review explores the current state of research on sewage sludge pyrolysis for the production of liquid fuels. With increasing amounts of sewage sludge posing disposal challenges, pyrolysis offers a promising alternative for waste management. The process converts sewage sludge into valuable products, including a liquid fraction with a significant heating value, comparable to petroleum-based fuels. The review details the various studies conducted, focusing on operational conditions, liquid yields, and the influence of factors such as temperature, residence time, and sludge composition. It also examines the physicochemical properties of the resulting liquid and potential applications, while acknowledging the technical and economic challenges that have affected previous industrial attempts.

Detailed Table of Contents:

• 1. Introduction
  • 1.1. The problematic disposal of sewage sludge
  • 1.2. The need for valorization alternatives
  • 1.3. Pyrolysis: a potential method for sewage sludge management
• 2. Sewage sludge composition and characteristics
• 3. Types of studies about sewage sludge pyrolysis
  • 3.1. Thermogravimetric pyrolysis studies
  • 3.2. Analytical pyrolysis
  • 3.3. Pyrolysis for the production of solid adsorbents
  • 3.4. Pyrolysis for obtaining a syn-gas
  • 3.5. Pyrolysis for liquid production
• 4. State of the art of sewage sludge pyrolysis for liquid production
  • 4.1. Operational conditions in sewage sludge pyrolysis for liquid production
    • 4.1.1. Non-catalytic pyrolysis
    • 4.1.2. Catalytic pyrolysis
  • 4.2. Liquid yield: influence of various parameters
    • 4.2.1. Influence of temperature
    • 4.2.2. Influence of gas residence time
    • 4.2.3. Influence of solid feed rate
    • 4.2.4. Influence of sewage sludge particle size
    • 4.2.5. Influence of reaction atmosphere composition
    • 4.2.6. Influence of sewage sludge composition
    • 4.2.7. Influence of the catalytic pyrolysis
  • 4.3. Physico-chemical properties of liquid
    • 4.3.1. Homogeneity
    • 4.3.2. Water content
    • 4.3.3. Heating value
    • 4.3.4. Solid content
    • 4.3.5. Viscosity
    • 4.3.6. pH and ammonia content
    • 4.3.7. Oil/tar ratio
    • 4.3.8. Ultimate analysis
    • 4.3.9. Toxicity
  • 4.4. Chemical composition of liquid and its phases: influence of various parameters
  • 4.5. By-products of sewage sludge pyrolysis for liquid production
    • 4.5.1. Char
    • 4.5.2. Gas
  • 4.6. Applicability of the process
• Conclusions
• Acknowledgements
• References