Ozone is frequently utilized in drinking water systems to eliminate iron and manganese, which can discolor water fixtures and clothing washed with the water. Although these substances do not present health hazards, the oxidation of iron through aeration is only feasible when it is not complexed or when the reaction is performed under acidic conditions.
Under these circumstances, a more potent oxidizing agent, such as ozone, is required. Aeration cannot oxidize manganese, whether it is complexed or not. Spartan provides ozone generators and related equipment that are suitable for removing iron and manganese.
Although chlorine can be used to oxidize iron and manganese, it necessitates a significantly greater quantity of chlorine compared to ozone. This is because ozone possesses an oxidation potential that is 150% greater than chlorine. Furthermore, if organic matter is present in the water, the use of chlorine can lead to the development of THM.
Use Ozone to Remove Iron and Manganese
Several factors determine the use of ozone for removing iron and manganese. The subsequent conversation offers fundamental details on the necessary conditions and quantities of ozone. Pilot testing is essential to determine the precise amount of ozone required and the category of ozone generator equipment necessary.
Removal of Iron
Ferrous iron, or Fe(II), is the soluble form of iron. Ozone converts iron from Fe(II) to Fe(III), which is referred to as ferric iron. Fe(III) subsequently hydrolyzes to Fe(OH)3, resulting in the precipitation of a solid form that can be filtered.
The oxidation process necessitates 0.43 mg of ozone per mg of Fe(II). Excessive ozone can be utilized without any adverse consequences. Iron oxidizes within the pH range of 6-9.
Removal of Manganese
Ozone converts Mn (II) to MnO2 Mn (IV), which is insoluble and can be filtered out of the water. The oxidation process necessitates 0.88 mg of ozone per mg of Mn (II). Any additional ozone beyond this ratio will produce soluble Mn (VII), also known as permanganate.
If there is oxidizable organic matter in the water and sufficient contact time, permanganate will revert to MnO2 Mn (IV). The optimal pH for manganese oxidation is around 8.
Learn More about the Use of Ozone for Iron and Manganese Removal
Typically, if organic matter is present in water, a greater amount of ozone will be necessary than what is indicated above, as ozone will also oxidize these materials. The composition of the precipitate will be determined by the water chemistry and temperature.
It is crucial to acknowledge that at the beginning of the treatment process, ozone may strip iron and manganese deposits in the treatment plant. Therefore, during the initial phase, the levels of iron and manganese may remain high until these deposits are eliminated. Apart from eliminating iron and manganese, ozone provides additional benefits such as micro flocculation, which can lead to enhanced filtration.
Ozone utilization is not recommended in every circumstance. If the concentration of Br ion exceeds 100 micrograms, the formation of bromate might occur. Additionally, ozone will decompose prematurely if the water temperature exceeds 105 degrees Fahrenheit. Before selecting ozone, pilot testing should be conducted.