Introduction

Water treatment plants play a critical role in ensuring that water supply remains safe to drink by removing impurities and harmful microorganisms. One common practice in these plants is adding chlorine to water as a disinfectant. Chlorine is a powerful chemical that can kill bacteria and other viruses, but why is it added to water in the first place? In this article, we will dive deeper into the reasons behind this practice.

Benefits of Chlorine as a Disinfectant

Chlorine has been a popular disinfectant for over a century due to its effectiveness in killing bacteria and viruses. It works by oxidizing the cell membranes of these microorganisms, rendering them harmless. Chlorine can also penetrate biofilm, the slimy layer that can encapsulate bacteria and other harmful substances, thereby eradicating them. More importantly, it has a residual effect that can keep the water disinfected even after the treatment process, making it an ideal disinfectant for water treatment plants.

Microorganisms that Chlorine Can Kill

Water supplied from the source is often contaminated with microorganisms that can cause harm to humans. Chlorine can kill or inactivate these microorganisms, thereby making the water safe to drink. Some of the common microorganisms that chlorine can kill include bacteria such as Salmonella, Shigella, and E. coli, as well as viruses such as poliovirus and hepatitis A. Additionally, chlorine can also eliminate protozoa, including Giardia and Cryptosporidium, which are resistant to many other disinfectants.

Chlorine Dosage and pH Control

Adding too little or too much chlorine to the water can compromise the disinfection process. To ensure that the right amount of chlorine is added, water treatment plants must consider several factors, including the pH level of the water. The optimum pH range for chlorine disinfection is between 6.5 and 7.5. Below or above this range can reduce the efficiency of chlorine's disinfection capabilities. Therefore, water treatment plants must monitor and control the pH level of their water supply to ensure the disinfection process is effective.

Health Risks of Chlorine

While chlorine plays an essential role in disinfecting water, it may also have health risks. Chlorine can combine with organic compounds in the water to form disinfection byproducts (DBPs), including trihalomethanes and haloacetic acids, which have been linked to cancer in animal studies. Additionally, chlorine exposure can cause skin and eye irritation, respiratory problems, and digestive issues. To reduce these risks, water treatment plants must carefully regulate the chlorine dosage and monitor the DBP levels in the water supply regularly.

Conclusion

In summary, chlorine is an essential disinfectant in water treatment plants due to its effectiveness in killing bacteria and viruses. It has the ability to penetrate biofilm and has a residual effect, making it an efficient disinfectant. However, chlorine can also have health risks if used improperly. To ensure that the water supply remains safe for consumption, water treatment plants must be vigilant in regulating the chlorine dosage and pH levels, as well as monitoring the DBP levels regularly. By doing so, they can continue to provide clean and safe water supply to households and businesses alike.