The inactivation of bacteriophage MS2 by sodium hypochlorite in the presence of particles

Abstract The inactivation of bacteriophage MS2 by sodium hypochlorite was investigated to understand the effect of solution chemistry on the disinfection efficacy in the presence of particles. Kaolinite and Microcystis aeruginosa (M. aeruginosa) were used as the models of inorganic and organic particles to simulate high turbidity and algal cells, respectively, in drinking water sources. In both particle-containing solutions, lower pH, the presence of cations (di-valent Ca2+) and natural organic matters (NOM) were regarded as the main factors to influence the aggregation and inactivation of MS2. The results showed that MS2 aggregated in all solutions at pH 3.0, protecting the inner viruses. At pH 7.0, the presence of Na+ cations (0-200 mmol/L) did not affect the inactivation efficacy of MS2, which always followed the order of particles-free ≈ kaolinite > M. aeruginosa. The inactivation efficacy of MS2 in the presence of Ca2+ cations followed the order of kaolinite > particles-free > M. aeruginosa at 0-50 mmol/L Ca2+ cations, while the inactivation efficacy remained almost constant in the range of 100-200 mmol/L Ca2+ cations. By contrast, kaolinite offered not enough protection to adsorbed MS2, but MS2 aggregation decreased disinfection efficacy at a high concentration of Ca2+ cations. Moreover, the presence of humic acid as NOM decreased the inactivation of MS2 more significantly than M. aeruginosa due to the more consumption of free chlorine from humic acids. Therefore, the co-existence of NOM and di-valent Ca2+ cations are potential challenges for the inactivation of viruses by sodium hypochlorite in safe drinking water.