Hydrogen Sulfide, (H2S), is a common taste and odor compound found in groundwater supplies. OxyPure hydrogen peroxide can effectively oxidize H2S. The reaction products can be controlled by pH adjustment. Under alkaline conditions (pH >8) the predominant reaction product is soluble sulfate (SO4=), and therefore turbidity is minimized. At this pH, most sulfides will be found in the soluble S= form, The oxidation of S= is shown below:

(for pH >8)
S= + 4 H₂O₂ ----> SO₄= + 4 H₂O

As can observed by the above reaction, the H2O2:S= ratio under alkaline conditions is 4:1.

Under neutral conditions (pH 7), OxyPure hydrogen peroxide will oxidize H2S to primarily colloidal sulfur. This reaction proceeds accordingly:

H₂S + H₂O₂ ----> S + 2 H₂O

The stoichiometric relationship under neutral pH conditions is 1:1 H2O2:H2S. The resultant colloidal sulfur is readily removed during flocculation/precipitation or filtration steps.

Iron Precipitation (Groundwater)

The removal of iron from drinking water sources is aesthetically and operationally advantageous, since iron can discolor the water, spot laundry, and stain plumbing fixtures. In addition, the growth of iron bacteria can impart objectionable taste as well as biofouling in the water system.

OxyPure hydrogen peroxide is very effective for the oxidation and precipitation of iron. OxyPure rapidly oxidizes iron to form dense, easily settled floc which conventional flocculation/precipitation and filtration systems readily remove. The oxidation of ferrous (Fe+2) to ferric (Fe+3) iron by OxyPure is shown here:

1.) 2 Fe⁺² + H₂O₂ + 2 H⁺ ----> 2 Fe⁺³ + 2 H₂O

(for pH > 7)
2.) Fe⁺³ + 3 H₂O ----> Fe(OH)₃ (precip.) + 3 H⁺

The approximate OxyPure : Fe+2 ratio is 0.5

Taste and Odor Removal - Ozone Enhancement (Surface Water)

The treatment of drinking water with OxyPure hydrogen peroxide and ozone combinations is increasingly being use for enhanced taste and odor removal and organic oxidation. The use of OxyPure hydrogen peroxide in conjunction with ozone (H2O2/O3) results in the formation of the powerful hydroxyl radical (OH*). The hydroxyl radical is second only to fluorine in oxidation potential and results in more effective destruction of organic contaminants and taste and odor compounds than ozone alone. The formation of the hydroxyl radical from ozone and hydrogen peroxide proceeds accordingly:

H₂O₂ + O₃ ----> 2 OH* + 3/2 O₂

Due to the synergistic effect of H2O2/O3, drinking water facilities can actually reduce the amount of ozone required to achieve effective T&O reduction or contaminant removal. This can result in substantial cost savings. H2O2:O3 ratios are typically in the range of 0.4 - 0.5.

Residual Ozone Destruction (Surface Water)

Ozone treated drinking water can contain small quantities of residual ozone that could be released into the atmosphere in subsequent treatment stages, e.g. tanks, filters, etc. OxyPure hydrogen peroxide can be added to ensure destruction of residual ozone and minimize ozone release to the atmosphere. This reaction is extremely rapid and proceeds as follows:

H₂O₂ + O₃ ----> 2 OH* + 3/2 O₂ ----> H₂O + 2 O₂

For destruction of 1 mg/L ozone, 1.4 mg/L 50% OxyPure is required.

Potassium Permanganate Replacement (Taste and Odor Removal in Surface Water)

Many surface water supplies contain objectionable taste and odor compounds. Many of these compounds, such as geosmin and 2-methyl-isoborneol (MIB) can be treated with hydrogen peroxide (H2O2) or potassium permanganate (KMnO4). In a study conducted by William H. Glaze ⁽¹⁾, hydrogen peroxide was more effective than potassium permanganate for the removal of geosmin, MIB and dimethyl trisulfide, and was comparable to KMnO4 for the removal of 1-heptanal.

For hydrogen peroxide, 2 potential mechanisms may be at work for the removal of the taste and odor compounds noted above:

1. Direct chemical oxidation, where H2O2 reacts with the taste and odor compound to render them less objectionable.
2. Enhanced flocculation, where the presence of H2O2 in the raw water results in a synergistic effect with flocculants such as aluminum sulfate.