Lenntech - Oxidants for Water Treatment Chemicals
Chemical oxidation processes use (chemical) oxidants to reduce COD/BOD levels, and to remove both organic and oxidisable inorganic components. The processes can completely oxidise organic materials to carbon dioxide and water, although it is often not necessary to operate the processes to this level of treatment.
A wide variety of oxidation chemicals are available. Examples are:
- Hydrogen peroxide;
- Ozone;
- Combined ozone & peroxide;
- Oxygen.
Hydrogen peroxide
Hydrogen peroxide is widely used thanks to its properties; it is a safe, effective, powerful and versatile oxidant. The main applications of H2O2 are oxidation to aid odour control and corrosion control, organic oxidation, metal oxidation and toxicity oxidation. The most difficult pollutants to oxidize may require H2O2 to be activated with catalysts such as iron, copper, manganese or other transition metal compounds.
Ozone
Ozone cannot only be applied as a disinfectant; it can also aid the removal of contaminants from water by means of oxidation. Ozone then purifies water by breaking up organic contaminants and converting inorganic contaminants to an insoluble form that can then be filtered out. The Ozone system can remove up to twenty-five contaminants.
Chemicals that can be oxidized with ozone are:
Absorbable organic halogens;
- Nitrite;
- Iron;
- Manganese;
- Cyanide;
- Pesticides;
- Nitrogen oxides;
- Odorous substances;
- Chlorinated hydrocarbons;
- PCB`s.
Oxygen
Oxygen can also be applied as an oxidant, for instance to realize the oxidation of iron and manganese. The reactions that occur during oxidation by oxygen are usually quite similar.
These are the reactions of the oxidation of iron and manganese with oxygen:
2 Fe2+ + O2 + 2 OH- -> Fe2O3 + H2O
2 Mn2+ + O2 + 4 OH- -> 2 MnO2 + 2 H2O