Hydrogen sulfide is a gas present in some waters. There is never any doubt as to when it is present due to its offensive "rotten egg" odor. Obnoxious as is the taste and odor of hydrogen sulfide, these are only two of the problems it presents. It promotes corrosion due to its activity as a weak acid; further, its presence in air causes silver to tarnish in a matter of seconds. High concentrates of hydrogen sulfide gas are both flammable and poisonous. High concentration of dissolved hydrogen sulfide or iron can foul the bed of an ion exchange softener. Its continued presence will lead to lower and lower capacity and may finally necessitate replacement of the resin bed. Iron is a very common element often found in ground water.  Iron may be found in several forms in water. The two most common are ferrous (dissolved) or ferric (rust particles). Iron bacteria are also common and thrive on iron, which it actually uses in their metabolic processes.  Iron present in water can cause staining and/or impart a metallic or distorted flavor to beverages. Iron bacteria can cause staining, plugging, and taste and odor problems in a water system, in even when iron levels are very low.

TREATMENT ALTERNATIVES

Many different chemical treatment approaches have been used to control or treat hydrogen sulfide or iron.

CHLORINE: Though a strong oxidizer is nonselective, requires large doses, and can react with organic compounds to form chlorinated organics, which increase effluent toxicity.

POTASSIUM PERMANGANATE: Another strong oxidizer is a hard‑to‑handle purple powder. It also adds manganese to the system, which precipitates out as manganese dioxide, which is an unsightly brownish‑black stain.

HYDROGEN PEROXIDE: Is a strong oxidizer that reacts quickly and specifically with hydrogen sulfide at a theoretical dosing ratio of about 1:1 (weight). Reaction byproducts are harmless, consisting of sulfur, sulfate, water, and oxygen.  It will also react quickly and specifically with iron (ferrous) at a theoretical dosing of about 0.3:1 (weight).  Reaction byproducts are harmless, consisting of iron (ferric), water and oxygen. Reaction times will occur within minutes or less.

Hydrogen peroxide combine advantages not obtainable with any other single form of sulfide or iron control. It is cost effective, component specific, and forms no toxic byproducts. It is a stable oxidant, having a natural decomposition rate in storage of less than 2% per year.

Versatility of hydrogen peroxide

Hydrogen peroxide is versatile, it can be used for many applications. It can be used in all media; air, water, waste water and soils. It is sometimes used combined with other agents, to enhance and accelerate processes. Hydrogen peroxide is most commonly used to remove pollutants from waste water and from air. It contests bacterial growth (for example bio fouling in water systems) and it can enhance bacterial growth (for example bio remediation of polluted soils and ground water) through oxygen addition. It can also be used to treat pollutions that can be easily oxidized (for example iron and sulfides) and pollutions that are difficult to oxidize (for example dissolved solids, gasoline and pesticides).

Finally, it can be used to bleach paper, textile, teeth and hair or to produce food, minerals, petrochemical substances or washing powder. In pure form, hydrogen peroxide is used as an oxygen provider to drive Russian submarines. 

THE OXYLOX WATER TREATMENT SYSTEM

Water Specialties Group, Inc. has designed the Oxylox System^TM, utilizing hydrogen peroxide, to treat total sulfide levels in excess of 300 ppm and iron levels up to 30 ppm, while controlling iron related and sulfate reducing bacteria. The Oxylox System is easy to install and requires little maintenance. In most cases, chlorine is eliminated, as well as, large bulky retention tanks. Proprietary valve control configuration and media, rapid in-line mixing, and corrosion resistant components are designed to last for years in even the most difficult water treatment applications.

Is hydrogen peroxide used for drinking water disinfection?

Among other applications, hydrogen peroxide is used as a disinfectant. It is used to treat inflammation of the gums and to disinfect (drinking) water. It is also used to combat excessive microbial growth in water systems and cooling towers. In the United States, hydrogen peroxide is used more and more frequently to treat individual water supplies. It is used to prevent the formation of colors, tastes, corrosion and scaling by pollution degradation (iron, manganese, sulfates) and micro-organism degradation. Hydrogen peroxide reacts very fast. It will than disintegrate into hydrogen and water, without the formation of byproducts. This increases the amount of oxygen in water.

The disinfection mechanism of hydrogen peroxide is based on the release of free oxygen radicals:  H₂O₂ ---> H₂O + O₂
 

In the 1950's, hydrogen peroxide was first used for drinking water disinfection in Eastern Europe. It is known for its high oxidative and biocide efficiency. Hydrogen peroxide has not been used often for drinking water disinfection, but it's popularity seems to increase. It is often used combined with ozone, silver or UV. 

Is hydrogen peroxide used for swimming pool disinfection?

The application of peroxides for disinfection and water treatment are limited. Recently, more stable forms have been developed, which can be used for application in swimming pools. Hydrogen peroxide disinfection requires a high dose. The main disadvantage is the small disinfecting and oxidizing ability of hydrogen peroxide at active concentrations (tens of milligrams per liter), which are required for swimming pool disinfection. Another problem is the quick decomposition of hydrogen peroxide in water and the presence of oxygen radicals. Through stabilizer addition, the decomposition of hydrogen peroxide is delayed and the disinfection ability can be maintained.