6.2.8 Chlorination 
Chlorination was carried out in one-litre amber glass bottles at room temperature (21 ± 2 °C). Free chlorine was added to each litre of simulated drinking water to achieve a Cl₂ concentration of 9.0 mg/L. UV irradiation was conducted with a 254 nm wavelength light source from a 41 W low-pressure mercury lamp (Light Sources, Orange, CT, USA) (Huang et al., 2019). A quasi-collimated beam with a 254 nm wavelength, generated by 41 W low-pressure mercury lamps (Light Sources, Orange, CT, USA), was used for UV irradiation (Huang et al., 2019). The comparison of inactivation rates between antibiotic-resistant bacteria and general heterotrophic bacteria during chlorination highlights the relative resistance of antibiotic-resistant strains to chlorine. The bacterial response, survival, and inactivation patterns of both heterotrophic and antibiotic-resistant bacteria during chlorination were assessed. Data suggest that ampicillin- and penicillin-resistant bacteria in secondary wastewater are more susceptible to chlorine than other bacteria due to bacterial inactivation (Templeton et al., 2009).