How to Treat the Hydrogen Sulfide of Wastewater

Hydrogen sulfide can sometimes be a tough challenge to tackle in waste water systems. In high concentrations, it becomes toxic. At low concentrations, its foul odor is a nuisance and its potential for corrosion can cause a problem. Typically, hydrogen sulfide in waste water is produced by sulfate-reducing bacteria that thrive in oxygen-poor environments. The best method to remove hydrogen sulfide or prevent its formation depends on the type of system, the scale of the problem and cost considerations. The article below briefly outlines several alternative methods.

Things You'll Need

• Chlorine dioxide
• Calcium nitrate or sodium nitrate
• Iron salts
• Hydrogen peroxide

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Instructions

• 1

  Add chlorine dioxide to reduce hydrogen sulfide levels, chlorinate waste water and kill sulfate-reducing bacteria. Chlorine dioxide reacts rapidly with hydrogen sulfide to form soluble byproducts. It will also attack the biofilms of anaerobic bacteria that form on sludge or slow-moving effluent. The dose varies depending on the amount of effluent to be treated.

• 2

  Add calcium or sodium nitrate to reduce the rate of hydrogen sulfide formation. Sulfate-reducing bacteria metabolize nitrate in preference to sulfate, so if nitrates are available, they will use these rather than the sulfates. If you opt for nitrate treatment, it's important not to overdose, since this could make sewage treatment more difficult. The optimal dose will depend on the amount of effluent and the type of system.

• 3

  Apply hydrogen peroxide to the waste water system. Hydrogen peroxide will react rapidly with hydrogen sulfide. It's consumed quickly, so it should be added as close as possible to the point where it's necessary to neutralize the H2S. OxyChem recommends an application of 1 to 3 milligrams per liter of hydrogen peroxide for every 1 milligram per liter of hydrogen sulfide.

• 4

  Add iron salts to the effluent. Iron salts (either ferric or ferrous) react with hydrogen sulfide to form an insoluble precipitate, thereby removing the hydrogen sulfide from the wastew ater. The iron sulfides can be filtered out at the treatment plant. OxyChem recommends applying 3 to 5 milligrams per liter for every 1 milligram per liter of hydrogen sulfide.

• 5

  Design your waste water system to ensure optimal flow. If you're building a new system, it's important to ensure the flow is sufficient to prevent stagnation, since stagnation can encourage the grow of sulfate-reducing bacteria. According to an article in Water and Wastes Digest, a flow rate of at least two feet per second is best.