Comparison of Online Sensors for Liquid Phase Hydrogen Sulphide Monitoring in Sewer Systems

Daneish Despot,Matthias Barjenbruch,Micaela Pacheco Fernández

doi:10.3390/w13131876

Abstract

Hydrogen sulfide (H2S) related to wastewater in sewer systems is known for causing significant problems of corrosion and odor nuisance. Sewer systems severely affected by H2S typically rely on online H2S gas sensors for monitoring and control. However, these H2S gas sensors only provide information about the H2S emission potential at the point being monitored, which is sometimes inadequate to design control measures. In this study, a comparison of three market-ready online sensors capable of liquid-phase H2S detection in sewer systems was assessed and compared. Two of the three sensors are based on UV/Vis spectrophotometry, while the other adapted the design and principles of a Clark-type electrochemical microsensor. The H2S measurements of the sensors were statistically compared to a standard laboratory method at first. Following that, the performance of the online sensors was evaluated under realistic sewer conditions using the Berlin Water Company (BWB) research sewer pilot plant. Test applications representing scenarios of typical H2S concentrations found in sulfide-affected sewers and during control measures were simulated. The UV/Vis spectrometers showed that the performance of the sensors was highly dependent on the calibration type and measurements used for deriving the calibration function. The electrochemical sensor showed high sensitivity by responding to alternating anaerobic/anoxic conditions simulated during nitrate dosing. All sensors were prone to measurement disturbances due to high amounts of sanitary solids in wastewater at the study site and required continuous maintenance for reliable measurements. Finally, a summary of the key attributes and limitations of the sensors compared for liquid phase H2S detection is outlined.

Highlights

IntroductionOdor and corrosion are two of the major problems associated with sewer systems
Published: 5 July 2021Odor and corrosion are two of the major problems associated with sewer systems.These problems are related to the formation of hydrogen sulfide (H2 S) under anaerobic conditions in sewers
Sulfate present in the wastewater is reduced by the sulfate-reducing bacteria (SRB)—primarily residing in the biofilms found on the sewer walls and in sewer sediments producing H2 S, that diffuse into the flowing wastewater [1,2]

Summary

Introduction

Odor and corrosion are two of the major problems associated with sewer systems. These problems are related to the formation of hydrogen sulfide (H2 S) under anaerobic conditions in sewers. Under these conditions, sulfate present in the wastewater is reduced by the sulfate-reducing bacteria (SRB)—primarily residing in the biofilms found on the sewer walls and in sewer sediments producing H2 S, that diffuse into the flowing wastewater [1,2]. Total dissolved sulfide is used as a sum parameter to represent the amount of HS− and H2 S present in the wastewater. The molecular form (H2 S) is released to the gas phase, and is typically used to quantify the extent of the odor and corrosion problems in wastewater systems [3]. Monitoring hydrogen sulfide or its sum parameter total dissolved sulfide (H2 S + HS− )

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Conclusion