What is one of the primary concerns when using chlorine for disinfection in water treatment?

One of the primary concerns when using chlorine for disinfection in water treatment is that it can form harmful by-products. When chlorine is added to water, it can react with organic matter and other compounds present in the water, leading to the formation of disinfection by-products (DBPs) such as trihalomethanes (THMs) and haloacetic acids (HAAs). These by-products can pose health risks to humans, contributing to the potential for cancer and other health issues upon long-term exposure. Therefore, while chlorine effectively kills pathogens, the formation of these by-products necessitates careful monitoring and management to ensure water safety and compliance with health regulations.

In contrast, other concerns mentioned involve issues that are either not primary or are less significant in the context of chlorine disinfection. For example, while chlorine may slightly affect pH, it typically does not cause significant increases that would be a major concern. High energy consumption is more relevant to certain alternative disinfection methods rather than chlorine itself. Lastly, while chlorine is highly effective against many pathogens, it is not entirely effective against all types, particularly some viruses and protozoa, but this issue typically does not overshadow the significance of by-product formation.