Water often goes through a purification process to ensure that it is safe for a designated purpose. During the purification process unwanted things in the water are removed such as biological contaminants, suspended solids, gases and other pollutants. Water is typically purified for human consumption, however it is done for other purposes too. Sometimes there are medical, pharmacological, chemical or industrial applications that require purified water as well. This liquid filtration process includes several steps before the water is safe for its designated use.
First off, where does the world's water supply come from? There are several sources of water; groundwater, lakes and reservoirs, rivers, rainwater and more. Water can even be extracted from the air. To do so, air must be chilled, which in turn creates condensed water vapor. But, regardless of where the water came from, the same six steps are involved with the liquid filtration process.
Step 1 - Coagulation
Coagulants are added to the water. A coagulant is any substance that causes coagulation. With chilled water filtration, common coagulants include aluminum, lime or iron. When one of these coagulants is added to the water being purified, unwanted particulates begin to clump together.
Step 2 - Flocculation
Once coagulation has begun, flocculation is next, which clarifies the water. This process involves shaking the water in order to cause the smaller coagulated pieces to lump into larger groups called flocs.
Step 3 - Sedimentation
After coagulation and flocculation, the water is left to sit for 24 hours. This allows the clumps to settle to the bottom of the container.
Step 4 - Filtration
Once all the clumps created from coagulation and flocculation have settled to the bottom, the next step is liquid filtration. This removes all the unwanted elements from the water that gathered at the bottom during the sedimentation step.
Step 5 - Disinfection
Following filtration, the water is disinfected, usually with chlorine.
Step 6 - Aeration
The finally step in this process is aeration. This allows other contaminants, like radon, to be removed.
After step six, the water is ready for human consumption or its other intended use.
When it comes to water for human consumption, even after the purification process, some opt for an additional system, such as a process water filter for their kitchen faucet. The fear is that there are chemicals and other pollutants in the drinking water. These filters are able to remove volatile organic chemicals, heavy metals, fluoride and endocrine disruption chemicals.