Hydrogen Sulfide Treatment in a Wastewater Collection System

Collection System: 0.2 MGD

Hydrogen Sulfide in Wastewater Collection Systems

Wastewater collection systems can develop elevated concentrations of hydrogen sulfide (H₂S), particularly when anaerobic conditions are present.

H₂S is produced when sulfate-reducing bacteria (SRB) break down organic compounds under oxygen-limited conditions. Sewer lines, force mains, lift stations, and other collection infrastructure can provide favorable environments for these bacteria when wastewater remains anaerobic for extended periods.

Several wastewater conditions can influence hydrogen sulfide production, including:

  • Temperature

  • pH

  • Conductivity

  • Wastewater flow rate

  • Detention time

  • Organic loading

  • Dissolved oxygen

Understanding these factors can help wastewater operators identify conditions that contribute to excessive H₂S formation.

Why Hydrogen Sulfide Is a Wastewater Management Concern

High H₂S concentrations can create significant operational, infrastructure, and safety challenges.

Hydrogen sulfide is associated with:

  • Strong and unpleasant sewer odors

  • Corrosion of collection pipes

  • Damage to manholes and lift stations

  • Increased infrastructure maintenance

  • Potential health and safety risks for wastewater personnel

For these reasons, wastewater utilities actively monitor and manage hydrogen sulfide concentrations in collection systems.

Using Bioaugmentation for H₂S Control

Bioaugmentation can be used as part of a biological strategy to reduce conditions that favor sulfate-reducing bacteria.

Introducing selected populations of beneficial microorganisms can increase competition for available organic substrates and help shift the microbial balance within the wastewater system.

This approach may help reduce:

  • Hydrogen sulfide production

  • Sewer odors

  • Sulfide-related corrosion

  • Conditions that favor excessive SRB activity

The following case study describes the use of BioLynceus® ProBiotic Scrubber® OCC (PBOCC) to manage H₂S in a municipal wastewater collection system.

H₂S and Odor Problems in an Arizona Collection System

A municipality in Arizona was experiencing elevated hydrogen sulfide levels in its lift stations and manholes.

The H₂S contributed to corrosion within the collection infrastructure and produced strong sewer odors.

After several nearby residents submitted odor complaints, municipal wastewater management began searching for a treatment strategy to reduce hydrogen sulfide production and improve collection system conditions.

Treating the Collection System with ProBiotic Scrubber® OCC

The city selected bioaugmentation as part of its H₂S management strategy.

BioLynceus® ProBiotic Scrubber® OCC was introduced into several wastewater lines to help reduce hydrogen sulfide production and associated odors.

PBOCC contains a diverse population of live wastewater microorganisms designed to support biological activity and reduce conditions that favor excessive sulfate-reducing bacteria.

The treatment program was implemented to support H₂S reduction, odor control, microbial balance, and protection of wastewater collection infrastructure.

Figure 1. Hourly average H2S concentrations and air temperatures for line 1 of the collection system. Data was collected over three odalog sessions, [1] pre-treatment (November 6-16), [2] PBOCC treatment session 1 (November 10-18), and [3] treatment session 2 (March 4-13).

H₂S Concentrations Decreased During Treatment

Monitoring data from Line 1 showed a consistent reduction in hydrogen sulfide (H₂S) concentrations during treatment.

Average H₂S concentrations were:

  • 207 ppm before treatment

  • 114 ppm during Treatment Session 1

  • 30 ppm during Treatment Session 2

This represented an approximate 45% reduction in H₂S during the first treatment session and an 86% reduction during the second treatment session compared with pretreatment conditions.

Wastewater Temperature May Have Influenced H₂S Reduction

Air temperature decreased by approximately 7°F between monitoring sessions, suggesting that wastewater temperatures may also have declined.

Temperature is an important factor in hydrogen sulfide production.

According to the U.S. Environmental Protection Agency's Design Manual for Odor and Corrosion Control in Sanitary Sewerage Systems and Treatment Plants, sulfide production by sulfate-reducing bacteria (SRB) can increase as wastewater temperatures rise, up to approximately 30°C (86°F).

Therefore, cooler wastewater conditions may have contributed to part of the measured H₂S reduction.

However, the decrease from 207 ppm before treatment to 30 ppm during treatment was substantial and was unlikely to be explained by temperature changes alone.

Reduced H₂S and Sewer Odor Complaints

During treatment with ProBiotic Scrubber® OCC (PBOCC), the municipality reported no odor complaints from the treated collection system.

The treatment period was associated with:

  • Lower hydrogen sulfide concentrations

  • Reduced sewer odors

  • Improved collection system conditions

  • Fewer odor-related concerns from nearby residents

These results demonstrate how biological treatment can be incorporated into a broader hydrogen sulfide and odor-control program for wastewater collection systems.

Supporting H₂S Control with ProBiotic Scrubber® OCC

BioLynceus® ProBiotic Scrubber® OCC is designed to support hydrogen sulfide reduction, odor control, microbial balance, and wastewater collection system performance.

Reference

  1. U.S. Environmental Protection Agency (USEPA). (1985). Design Manual for Odor and Corrosion Control in Sanitary Sewerage Systems and Treatment Plants. EPA/625/1-85/018. Center for Environmental Research Information, Office of Research and Development, Cincinnati.