What Is Water Softening?
What Is Hard Water?
Before understanding water softening, we should first figure out what is hard water and soft water. Hard water contains high levels of calcium and magnesium ions, while soft water contains low levels of these ions. Hardness ions are usually combined with sulfate, chloride, carbonate or bicarbonate ions. Concentrations are usually expressed by converting them to calcium carbonate equivalents for consistency. Water hardness is usually measured in grains per gallon (gpg) or parts per million (ppm) and is classified as follows:
Water Softening Treatment
Water softening is the process of removing dissolved minerals, such as calcium and magnesium, from hard water. Hard water can cause problems such as scaling in pipes and water-using appliances, soap scum on shower curtains and dishes, and reduced efficiency of water heaters. The purpose of water softening treatment is to slow down or eliminate a series of adverse effects caused by hard water.
The ion exchange water softening process is a common method used to reduce the amount of calcium, magnesium, and other metal ions present in hard water. The process uses a resin bed exchange to remove hardness ions from the water supply. The process is as follows:
1. The resin bed consists of tiny plastic beads that have been chemically treated to attract and hold on to the hardness ions in the water. As the water flows through the resin bed, the hardness ions are exchanged for sodium ions, which are then released into the water supply.
2. When the resin bed becomes saturated with hardness ions, it must be regenerated. This is done by flushing the bed with a brine solution, which exchanges the sodium ions with the hardness ions and disposes of them. The brine solution is then rinsed from the resin bed before it is ready to be used again.
Ion Exchange Resins for Water Softening
There are four types of ion exchange resins that are commonly used for water softening:
- Strong Acid Cation Exchange Resin: It is the most common type of resin used for water softening. It is highly efficient in removing calcium and magnesium ions from hard water.
- Weak Acid Cation Exchange Resin: It is used in situations where the water has a relatively high pH level, as it is less aggressive than strong acid resins. It is also useful for removing other cations like iron and manganese.
- Strong Base Anion Exchange Resin: It is used to remove anions like bicarbonate and sulfate ions from hard water.
- Weak Base Anion Exchange Resin: It is used in situations where the water has a low pH level, as it is less aggressive than strong base resins. It is also useful for removing organic molecules and some heavy metals.
Overall, the choice of resin depends on the composition of the water being treated, the desired level of softness, and the available equipment for regeneration.
Related Ion Exchange Resins