Preoxidants
Air
Air injection is mostly used for H2S outgassing (sulphur odours). Air can also oxidize iron or manganese. However, it is better to use air only if the pH levels are close to being ideal for catalyst filters. We use a venturi to inject air into the water. We then use an air eliminator to remove the venturi before it reaches the taps.
Advantages of air :
- Low cost
- Great solution for H2S outgassing
- Improves the taste of the water
Disadvantage :
- Use only if pH level is ideal
Chlorine
Chlorine, also known as sodium hypochlorite (bleach), is used in a liquid form in the treatment of residential drinking water. Bleach is sold in different concentration levels (between 4% and 12%).
Chlorine is used to disinfect and oxidize certain metals (like iron, manganese and sulphur) or gases present in the water. Chlorine is also used to decolour water.
An appropriate dose of Chlorine can even remove tannins from the water (humic and fluvic acids that can cause a yellowish tea color). In most cases, we will remove any chlorine residuals with a carbon filter. This will eliminate the taste and any sub-products created by the chlorine. Chlorine injection in the water is done with a flow control pump.
Advantages of sodium hypochlorite :
- Easy to use
- Easy to get
- Adjustable and modifiable doses
- Excellent oxidant
- Low cost
Disadvantages :
- Can leave a bad taste
- Can leave sub-products that are a health hazard
Note : Chlorine sub-products can easily be absorbed by carbon filters. It's a matter of doing the required maintenance to avoid any chlorine side effects.
Potassium permanganate (KMnO4)
Permanganate is used to regenerate the oxidation layer in the green sand. It resembles the salt recharging process for the resin bead found in water softeners. Permanganate is added annually when chlorine is used as a oxidant aid to the green sand. Permanganate is added monthly if the green sand is used without chlorine.