A water purification process is any one of a number of methods used to create clean water from natural water sources or human drainage systems. The most common water purification process involves taking water from a constant source, such as a lake, stream or sewer system, and mechanically removing all the physical impurities. After the impurities are removed and the harmful organisms in the water are killed, the water is safe for use.
Generally, the first step in a water purification process is removing the water from its source. This generally means the water is pumped from it source system into a holding tank. This is actually a very important step; since these holding tanks allow the water to sit motionless, they allow many of the materials kept in suspension to separate out.
Once separated from its source water, the initial water purification process can begin. The first step is the tank. While the water is in the tank waiting to be processed, it undergoes a handful of preparation steps. Large physical objects like sticks and rocks are removed. Next, the pH of the water is adjusted to within a specific window. Lastly, sodium carbonate is put into salt-heavy water to begin a reaction that results in calcium carbonate.
Most processes use this point to disinfect the water. As the water moves from the holding tank to the purification area, harmful microbes in the water are killed. While chlorine-based methods were common in the past, these methods are used less today. The common modern methods include hydrogen peroxide, ozone and ultraviolet light.
The actual water purification process begins with flocculation. Very small particles are added to the water; these particles vary based on the source of the water and the location of the plant. These particles are naturally attracted to each other and many common impurities. The particles begin to combine with material in the water and one another until they make little balls of impurities. The water then enters a tank where the balls settle out to the bottom.
After settling, the water purification process moves to active filtering. There are a number of different filtering methods used, but most of them involve forcing the water through sand. Some processes go a step further, using a specialized polymer net that literally catches impurities as they go by. After filtration is complete, the water is either clean for human use or sent to settling ponds where it evaporates back into the local water system.