CWQA Position Statement

Hydrogen Peroxide (H2O2)

Hydrogen peroxide is a powerful oxidizing agent, more powerful than chlorine and potassium permanganate.  It is relatively safe and decomposes into oxygen ant water. It won't form disinfection byproducts, such as trihalomethanes (THMs), as chlorine does.  In low concentrations it has odour and is non-flammable.

Hydrogen peroxide has been gaining in popularity for the treatment of hydrogen sulfide and iron.  Catalytic carbon and redox media perform well with hydrogen peroxide pretreatment.

Many different grades of hydrogen peroxide are available from chemical manufacturers.  For potable water treatment, dealers should use only food grade.  Due to the volatility of highly concentrated H2O2.  Research all safety and handling procedures as recommended by the manufacturer.

One important note is that hydrogen peroxide can only be fed by a peristaltic pump.  Positive displacement diaphragm pumps will make the H2O2 "gas out," causing the pump to lose its prime.

Hydrogen peroxide should never be mixed with alkaline substances (soda ash, sodium hydroxide, hypochlorite, limestone or ammonia), which cause H2O2 in 8 per cent solution strength versus 35 per cent.

Iron and hydrogen sulfide may be the most difficult and challenging elements to treat because they can vary radically in chemical composition from job to job.  However, hydrogen peroxide can give popular filter media that extra boost of dissolved oxygen they require without side effects of chlorine.  Manganese dioxide, greensand or manganese dioxide-coated media are not recommended for direct contact with H2O2  because they possibly could leach manganese.

Hydrogen peroxide has also been used to greatly enhance the effectiveness of ozone and ultraviolet systems, but should not be used as a stand alone disinfectant.

[Water Technology magazine]

The general definition of Hydrogen Peroxide (H202) is:  A strong disinfectant and oxidizing agent used mostly in diluted water based solutions.  Peroxide can be formed in water with a 1948 angstrom mercury-vapor ultraviolet lamp.  Hydrogen Peroxide may be used in advanced oxidation processes in combination with ozone to encourage the formation of highly reactive hydroxyl radicals; this process is then called the Peroxone process.

To be more specific for doses of chemical feed levels for oxidation of iron, manganese and hydrogen sulfide in domestic water supplies, here are some figures:

Iron:
For each ppm Fe feed = 0.3 - 0.5 ppm, 20 minutes

Manganese:
For each ppm Mn feed = 0.8 - 1.0 ppm, 20 minutes

Hydrogen Sulfide:
For each ppm H2S feed = 1.0 - 1.5 ppm, 30 minutes

(all above figures are for minimum retention time).  When more than one constituent is to be oxidized (i.e. iron & H2S) add the above values to determine the total ppm feed needed to oxidize two or more.