Master’s thesis of Engineering: Impact of drought and water conservation on H2S formation in sewer pipes

Impact of Drought and Water Conservation on H₂S Formation in Sewer Pipes

Author: Chunyi Yuan

Field: Master of Engineering

Document Content: This thesis investigates the formation of hydrogen sulphide (H₂S) in sewer pipes, a significant issue causing odor nuisances, health risks, and corrosion of concrete pipes. The research focuses on the impact of drought and subsequent water conservation practices on H₂S generation. Reduced sewage flow due to water restrictions can alter sewer hydraulics, leading to decreased flushing and potentially increased H₂S buildup. The study aims to explore the relationship between various sewage characteristics, flow rates, and H₂S formation. An experimental setup simulating a sewer pipe was developed to investigate these factors. A two-phase mathematical model was also created to predict sulphide concentration in both the liquid and air phases within the sewer system. Field monitoring was conducted to validate the model and understand real-world conditions.

Detailed Table of Contents:

• Declaration
• Acknowledgements
• Abstract
• Contents
• List of Figures
• List of Tables
• Chapter One: Introduction
  • 1.1 Introduction
  • 1.2 Thesis Structure
• Chapter Two: Literature Review
  • 2.1 Introduction
  • 2.2 Sulphide Build-up in Sewer Systems
    • 2.2.1 Bacteria and Sewer Pipe Slime Layer
    • 2.2.2 Factors Affect Sulphide Build-up in Sewer Pipes
  • 2.3 Hydrogen Sulphide Emission in Sewer Pipes
  • 2.4 Sewer Pipe Corrosion
  • 2.5 Models for Prediction of H₂S in Sewer Pipes
    • 2.5.1 Models for Sulphide Build-up
    • 2.5.2 Hydrogen Sulphide Emission Prediction
    • 2.5.3 Sulphide Oxidation Rate
    • 2.5.4 Concrete Corrosion Rate
• Chapter Three: Materials and Methods
  • 3.1 Experimental Set-up
    • 3.1.1 Preliminary Experimental Set-up
    • 3.1.2 Final Experimental Set-up
  • 3.2 Materials
  • 3.3 Methods
    • 3.3.1 Development of Biological Growth
    • 3.3.2 Laboratory Sewer Pipe Runs
  • 3.4 Analysis
  • 3.5 Field Monitoring
    • 3.5.1 Monitoring Locations
    • 3.5.2 Sampling Procedure
• Chapter Four: Results and Discussion
  • 4.1 Introduction
  • 4.2 The Development of Biological Growth in the Laboratory Sewer Pipe
    • 4.2.1 Experimental Results in the Initial Stage
    • 4.2.2 Experimental Results during Postgate’s Grow Medium
    • 4.2.3 Experimental Results when Using Synthetic Sewage
  • 4.3 Performance of the Laboratory Sewer Pipe
    • 4.3.1 Sulphur Processes in the Laboratory Sewer pipe
    • 4.3.2 Sulphate Calibration
    • 4.3.3 Sulphate Reduction and Sulphide Build-up
    • 4.3.4 Mass Balances of Sulphate and Sulphide Concentration
  • 4.4 Factors Affecting the Concentration of Sulphide in the Liquid Phase and H₂S in the Air Phase
    • 4.4.1 Effect of Velocity on the Generation of Sulphide in Sewage and H₂S in the Atmosphere
    • 4.4.2 Effect of Sulphate Concentration on the Generation of Sulphide in Sewage and H₂S in the Atmosphere
    • 4.4.3 Effect of COD on the Generation of Sulphide in Sewage and H₂S in the Atmosphere
  • 4.5 Model to Predict Sulphide in Sewer System and Predicted Sewer Pipe Corrosion
    • 4.5.1 Two-phase Model
    • 4.5.2 Comparison of Prediction and Experimental Results
    • 4.5.3 Comparison of Sulphide Concentration Using the Two-Phase Model under Different Sewer Conditions
    • 4.5.4 Sulphide Oxidation Rate in the Liquid Phase
    • 4.5.5 Predict Concrete Sewer Pipe Corrosion Rate
  • 4.6 Field Monitoring Results
    • 4.6.1 Two-phase Model to Predict H₂S in Sewer Pipes
    • 4.6.2 Effect of Temperature on H₂S Concentration
    • 4.6.3 Effect of Sewage Constituent on H₂S Concentration
• Chapter Five: Conclusions
  • 5.1 Biological Growth of Sulphate Reducing Bacteria
  • 5.2 Laboratory Performance of Sewer Pipe
  • 5.3 Model for Prediction of Sulphide Concentrations
• References
• Appendix