Have you ever wondered what goes into your water? Or more importantly, what doesn’t go into it? You probably already suspect that a lot of work goes into making sure the water is clear and pure. But how are big bodies of water cleaned and freed of foreign material?
Mechanically removing particles from water
There are mechanisms used for removing solids from water. A circular clarifier is one of those mechanisms. The solids in the water are deposited from sedimentation. The job of a clarifier is to make sure the suspended solids or particulates are removed from the water to clarify it or to thicken it.
The impurities that collect at the bottom of the tank for discharging are called sludge. The particles that end up floating on the surface are called scum.
Pretreating before entering a clarifier
Clarification of water doesn’t involve just using a mechanism. Polyelectrolytes and ferric sulfate are two examples of coagulation and flocculation reagents. These are added to the water before it enters the clarifier so that finely suspended particles clump together. When they form denser and larger particles called flocs, the particles settle quickly. Separation of the solids becomes easy and efficient for the clarifier, and so it uses up less energy. It also lowers the downstream water treatment process volume.
Water for human consumption
Potable water undergoes a similar process to become safe. Flocculation reagents are introduced to the water and the clarifier removes the coagulate. The larger and heavier particles settle to the clarifier’s bottom, where it becomes part of the layer of sludge, which should be removed and disposed of regularly. The clarified water then goes through other processes so the water that reaches end-users are safe for drinking and storage.
There are many other processes for different purposes, such as for the treatment of waste water. Technology has improved immensely in making bodies of water safer for specific purposes, not just for human consumption.