Odor complaints from sanitary sewer systems are a persistent challenge for utilities, especially as water conservation and oversized infrastructure to accommodate future build-out can increase hydrogen sulfide emissions. Traditional chemical treatments are costly and require ongoing maintenance.
Challenge
Utilities needed a cost-effective, low-maintenance solution to reduce H₂S odors vented from manholes, while extending the service life of odor control media.
Solution
Researchers from the University of the Pacific and Lawrence Berkeley National Lab tested manhole odor control devices at four sites in California and Nevada. These devices combined pressure regulation (using a variable volume bladder and pressure relief valves) with adsorptive media — activated carbon, iron sponge, or zeolite — to treat vented gases before release.
Results
- High removal rates: Most sites achieved over 90% H₂S removal, with iron media performing best (up to 98% removal).
- Media longevity: Devices operated for eight to 12 months before media replacement was needed, thanks to reduced gas flow through the adsorptive media.
- Site variability: Performance depended on local conditions — sites with high gas flow saw lower removal rates, highlighting the importance of matching device design to site needs.
- Practical fit: Devices fit standard manholes and offered an economical, easily retrofitted solution.
Manhole odor control devices with flow moderation and adsorptive media are a practical, effective approach for reducing sewer odors. With proper site selection and media choice, utilities can achieve significant odor reduction and longer service intervals, improving community satisfaction and operational efficiency.
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