Which class of organism in wastewater is most resistant to chlorine disinfection?

The class of organisms in wastewater that is most resistant to chlorine disinfection is spores. Spores are formed by certain bacteria and are designed to withstand harsh environmental conditions, including exposure to disinfectants like chlorine. This resilience is due to their thick protective outer layers and dormant state, which enable them to survive when nutrients are scarce or when subjected to adverse conditions.

In the context of wastewater treatment, effective disinfection is crucial for preventing the spread of pathogens. While chlorine is widely used for disinfection, its efficiency varies among different types of organisms. Spores, being highly resistant, may survive chlorine treatments that effectively eliminate other organisms like bacteria, viruses, or protozoa. This characteristic poses challenges in wastewater management, as it necessitates additional treatment steps to ensure that spore-forming bacteria do not pose a risk to human health and the environment.