pH Correction

FOR NEUTRALISING ACID WATER AND REMINERALISING VERY PURE WATER

Acid water causes corrosion of pipe work and heating cylinders. Neutral water has a pH value of 7, and the maximum permitted pH is 9.5 which is alkaline.

A pH value below 7 is considered to be acid, and corrosion starts at levels below 6.5. A pH value below 6 is extremely aggressive. It is also difficult to remove Iron and Manganese from acid water, so often the first stage of Iron and Manganese removal is to trace the pH.

For waters in which the pH is not below 5, the simplest and safest way to raise the pH is to run it through a pressure vessel containing a bed of specially activated dolomitic limestone, a mixture of calcite and magnacite. The limestone gradually dissolves, increasing alkalinity.

Periodically, the dolomitic limestone will need to be topped up as its level decreases. The medium itself is inert and easy to handle.

For waters that are otherwise clean and pure a basic up-flow system is all that is required. For water with Iron or turbidity problems, a backwashing down flow system will be needed to remove accumulated debris.

Water with a pH of 5 and below is uncommon, but when it occurs it needs correcting with a liquid alkali such as caustic soda or soda ash which requires accurately controlled dosing and monitoring.

Specifying and Sizing
The contact time of the raw water with the pH correction media is most important for safety performance. The recommended maximum service flows for each system are shown in the Technical Details columns.

For every 10 mg/L CO2, alkalinity and total hardness will be raised by approximately 18 mg/L as CaCO3. Consumption - for each 10 mg/L CO2 removed, there will be a consumption of approximately 12 mg/L of media.

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Iron & Manganese Removal

Ultraviolet Sterilisation

Debris Filtration

Water Softening