How Do Water Treatment Plants Get Rid of Pathogens

Water is a very vital resource for all living organisms, including humans. However, with the increasing pollution and industrial activities, the purity of water is compromised. Hence, there is a need for water treatment plants to make it safe for drinking and other uses. Water treatment plants remove the impurities present in the water, including pathogens, which are harmful to human health. Let's explore how water treatment plants get rid of pathogens.

1. Coagulation and Flocculation

The first step in water treatment plants is coagulation and flocculation. Coagulation is the process of adding a coagulant such as alum to the water, which causes small particles to stick together or coagulate. The process of flocculation then follows, which involves gently mixing the water to form larger and heavier particles called flocs. These larger and heavier particles are then easy to remove using sedimentation and filtration processes.

2. Sedimentation

After coagulation and flocculation, the water is slowly passed through large sedimentation tanks. The heavy flocs settle to the bottom of the tank, while the clear water remaining at the top is then sent to the filtration process. Sedimentation removes about 90% of suspended solids and pathogens present in the water, making it cleaner.

3. Filtration

The water from the sedimentation tank is then passed through filters to remove small suspended particles that were not removed during the sedimentation process. The filters are made of sand, gravel, and charcoal, which remove dirt, debris, and pathogens. The activated carbon filters are also essential in removing the taste and odor of the water.

4. Disinfection

After filtration, the water undergoes disinfection to kill any remaining pathogens. The most common disinfection method is adding chlorine gas to the water. The chlorine kills harmful pathogens, including bacteria and viruses, by breaking down their cell walls, rendering them inactive. The chlorinated water is then left to settle for a while to allow enough contact time with the pathogens. Chlorine tablets and UV radiation can also be used for disinfection.

5. pH Adjustment

Finally, the treated water is tested for its pH level, which should be between 7 and 8.5. If the pH is not within the acceptable range, chemicals such as lime, soda ash, or caustic soda are added to adjust the pH level. The pH adjustment is critical because water that is too acidic or alkaline can cause health problems when consumed.

Conclusion

Water treatment plants play a critical role in making water safe for human consumption. The coagulation and flocculation, sedimentation, filtration, disinfection, and pH adjustment processes are all essential in removing pathogens and other impurities in the water. Clean water is essential for human health and well-being; hence, water treatment plants must ensure that the water is safe for consumption.