The toxic, foul-smelling, and highly corrosive gas hydrogen sulfide (H2S) poses a major challenge to wastewater utilities.
H2S is formed when wastewater is pumped through force mains, and the H2S induced odor and corrosion issues are commonly found in hotspots right after the discharge into the gravitational sewer system. Here, part of the dissolved H2S is released into the air, while another part remains in the sewage where it is transported further downstream in the network if left untreated.
Wastewater utilities typically use gas loggers to monitor H2S concentration changes in the diluted air below manhole covers. However, seeing as H2S is produced and transported in the wastewater and not in the air, wouldn’t it make more sense to measure it in the wastewater?
This case study thus investigates if continuous liquid-phase measurements can provide a better approach to H2S monitoring than gas-phase measurements and deliver better insights into how H2S impacts sewer hotspots.
To analyze the benefits of measuring H2S directly in the wastewater, three SulfiLoggerTM H2S sensors were installed in the same 3-metre deep force main discharge well at a Danish wastewater utility. Capable of continuously measuring H2S in both gas and liquid phase, the SulfiLoggerTM sensors were installed in the raw wastewater (A), in the headspace just above the wastewater (B), and in the headspace just below the manhole cover (C).