Question

Evidence is fairly strong that chlorine, used for wastewater disinfection, combines with organic material in wastewater to form trihalomethane and other disinfection byproducts that are suspected human carcinogens. Despite this health risk, chlorine remains the predominant disinfection method. Explain why.

Answer 1

Ozone and chlorine are the two most effective disinfectant. Ozone can easily oxidize the organic matter and destroy the bacteria but future contamination of water is issue but residual portion doesn't stay longer. Treatment with ozone is quite costly affair and can't be used everywhere. On the other hand, the freely available chlorine and the combined chlorine both have the disinfectant properties. Free chlorine gives the instantaneous disinfectant properties while the combined chlorine safeguards the future contamination. The freely available chlorine are effective in reacting with other elements and chlorine is a strong oxidising agent. Furthermore, disinfectant using chlorine is a cheap affair. The dossage of chlorine can be controlled effectively by break point analysis. Thus proper dossage of chlorine can be checked so that it doesn't have any negative impact. Thus, chlorine is still a preferred disinfectant inspite of health risk.