Sulfide Oxidation with Hydrogen Peroxide (H2O2) - Water and Wastewater - Chemical Water Treatment
Sulfide Odor Control Sulfide is found throughout the environment as a result of both natural and industrial processes. Most sulfide found in nature was produced biologically (under anaerobic conditions) and occurs as free hydrogen sulfide (H2S) - characterized by its rotten egg odor. We are most likely to encounter biogenic H2S in sour groundwaters, swamps and marshes, natural gas deposits, and sewage collection/treatment systems. Manmade sources of H2S typically occur as a result of natural materials containing sulfur (e.g., coal, gas and oil) being refined into industrial products. For a variety of reasons - aesthetics (odor control), health (toxicity), ecological (oxygen depletion in receiving waters), and economic (corrosion of equipment and infrastructure) - sulfide laden wastewaters must be handled carefully and remediated before they can be released to the environment. Typical discharge limits for sulfide are < 1 mg/L. Sulfide Treatment Alternatives There are dozens of alternatives for treating sulfide laden waters, ranging from simple air stripping (for the low levels present in groundwaters) to elaborate sulfur recovery plants (used to treat several tons per day at refineries and coal burning power plants). There are processes based on biology (using compost filters, scrubbing media, or inhibition/disinfection), chemistry (oxidation, precipitation, absorption, and combination), and physics (adsorption, volatilization, and incineration). Each process occupies a niche which is often defined by the scale and continuity of treatment, whether the sulfide is in solution or is a gas, the concentration of sulfide involved, and the disposition of the sulfide containing medium. However, for reasons relating to convenience and flexibility, chemical oxidation (using hydrogen peroxide) continues to grow in its scope of application. Treatment with Hydrogen Peroxide While other peroxygens such as permonosulfuric (Caro’s) acid, peracetic acid, and persulfates will oxidize sulfide, their use for this application is overkill. Hydrogen peroxide (H2O2) is considerably simpler and more cost-effective. H2O2 may control sulfides in two ways, depending on the application: Prevention - by providing dissolved oxygen which inhibits the septic conditions which lead to biological sulfide formation; and Destruction - by oxidizing sulfide to elemental sulfur or sulfate ion.