Common impurities in water may lead to scale or sludge deposits in boilers and cooling towers. Four easily identifiable impurities are Hardness, Alkalinity, Silica, and Iron.
- Hardness: Calcium and Magnesium minerals in the water.
- Alkalinity: Can be combined with hardness to form scale.
- Silica: Can form tenacious deposits on heat transfer equipment and power generation equipment.
- Iron: Can form very dense deposits on heat transfer equipment.
As only pure water is evaporated from cooling water and steam boiler systems, impurities remain and concentrate, increasing the potential for scale formation and sludge deposits. Scale and sludge deposits in boilers and cooling towers impede heat transfer, which leads to higher energy costs and can cause a loss of equipment operation and premature failure. The reason water is treated for scale and sludge control is to extract all of the beneficial characteristics of water, while neutralizing the negative effects of impurities in the water.