Reducing free residual chlorine using four simple physical methods in drinking water: effect of different parameters, monitoring microbial regrowth of culturable heterotrophic bacteria, and kinetic and thermodynamic studies

Abstract

While chlorination is critical for water disinfection, a knowledge gap includes the nature of free residual chlorine (FRC) decay, which was investigated using four physical methods (SSA, SSR with and without a lid, heating, and incubator shaker). Keeping water samples in SSA and SSR methods for 24 h resulted in the FRC decline by 62 and 51, respectively. The heterotrophic plate count (HPC) increased significantly between initial (3.17 ± 2.6–3.82 ± 1.1 CFU/mL) and final samples (6.7 ± 1.5–94.7 ± 4.72 CFU/mL) for both SSA and SSR methods. Thermodynamic behavior (ΔH versus ΔG) of FRC decay of the different methods was characterized. © 2020 Informa UK Limited, trading as Taylor & Francis Group.