Five Stages of Water Purification During Emergencies
August 5, 2022

The emergencies created by violence, conflicts, and displacements resulting from wars and disasters are extreme. The resulting emergencies often pose a threat to health. One way by which this happens is through the vulnerability of water and sanitation systems. For example, in cases of displacements, people might have to cope with the unhygienic state of water supply in the new location where they find themselves.

In situations like this, the general public should be equipped with the knowledge of the processes involved in water purification, as sanitation issues are issues of concern to public health. In this article, we’ll be giving a detailed explanation of the five steps involved in water purification.

1. Coagulation

The first step in purifying water is chemical coagulation. Chlorine dioxide is the first chemical that is added. Chlorine dioxide is an oxidant for breaking down organic matter like decaying leaves. Afterward, aluminum sulfate, a primary coagulant, is added to the water. To help strengthen the bonding chains of the primary coagulant, a polymeric organic compound is added.

The addition of the coagulants takes place at the rapid mix unit. This unit creates vigorous mixing energy that helps to disperse the coagulants into the raw water. As the coagulation process begins, fine particles clump together and become easily removable by filtering, draining, or skimming.

2. Flocculation

After coagulation, the water goes through the flocculation process. This process is a slow stirring one, and it causes the coagulated particles to flocculate, promoting contact between the water sediments and floc particles.

These contacts result from the stirring created by hydraulic or mechanical means. There are two groups of flocculation basins containing mechanical paddles for mixing to allow easy passage so that there can be a gentle stirring of the coagulated water. The formed floc attracts the water particulates, thereby forming larger particles that make removing them easier.

3. Sedimentation

The flocculated water is passed through the sedimentation process next. This process is mainly necessary for removing suspended solid particles with a higher density than water and reducing particulate filter loads.

This process is accomplished by reducing the velocity of the water so low that it can convey settleable suspended particles, allowing forces of gravity to remove suspended particles. This sedimentation process removes up to 90% of the solids in water.

4. Disinfection

The water now flows to the filtration facility. At the prechlorination stage, you should add chlorine to the water before it arrives at the filtration facility. This disinfection process helps to inactivate many microbes in water, especially the pathogenic ones, whether parasites, bacteria, or viruses. These organisms cause waterborne diseases such as cholera, typhoid, dysentery, etc.

5. Filtration

Filtration involves passing water through materials like a coal bed, sand, or other granular materials to take out particulate impurities that survive the sedimentation process. Water treatment plants use multimedia fast rate gravity filter beds. Potable water gotten from the filter beds is sent to a Backwash Recovery Pond where the water is made to settle.

Adequate knowledge of the steps involved in purifying water will lessen the risks of exposure to public health challenges that may result from the intake of dirty water during emergencies. This guide will be helpful in that regard.