Cold lime softening technology is a well-known and very trusted method for removing hardness and alkalinity caused by minerals such as calcium, magnesium, iron and silica from drinking water. Cold lime softening is a proven and reliable method that dates back to 1841 when lime was added to the Thames River. Just as today, the minerals were attracted to the lime and created a sludge that settled at the bottom of the river. In this way, the clean water could be easily removed from the top. Modern cold lime softening techniques use the same principles to reliably remove hardness and alkalinity.
At USALCO, lime, sodium hydroxide, and sodium aluminate are usually recommended to cold lime soften in varying degrees and or combinations. The characteristics of the influent water to be treated, such as the levels of calcium, magnesium, iron and silica in the raw water, as well as the desired finished water quality are the primary factors that determine use and application of the right chemicals. USALCO delivers Sodium Aluminate to municipalities and companies for cold lime softening. We supply the product in bulk quantities in dedicated transportation equipment to insure quality. USALCO has multiple plants. USALCO offers free jar testing and trials to optimize chemical dosages.
For example, USALCO’s LSA 38 (liquid sodium aluminate) has been proven to be extremely effective where additional and or improved magnesium removal is required. USALCO LSA 38 also works to provide the following treatment benefits:
- Increases silica removal
- Provides the needed hydroxyl ion (OH-) for magnesium reduction without increasing calcium hardness in treated water
- Hydrolysis of sodium aluminate to aluminum hydroxide aids in floc formation
As in the historical example, the cold lime softening treatment converts the soluble contaminants (i.e., hardness, alkalinity) to insoluble compounds that sink to the bottom of your settling basin or clarifier. The clean water can be pulled from the top and the compounds remain at the bottom. These compounds can then be easily removed by settling and mechanical separation.
Cold lime softening is a form of precipitation softening that works well at ambient temperatures. It works well for both temporary and permanent hardness. Carbonate or temporary hardness are calcium and magnesium associated with carbonates or bicarbonates in the water. Non-carbonate or permanent hardness are calcium and magnesium in a form combined with chlorides, sulfates, and nitrates in the water.
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