Abstract
To elucidate the effects of suspended particles on UV disinfection of water, inactivation properties of Escherichia coli and coliphage MS2 were tested in the presence of particles including carbon black (CB) and polystyrene (PS) beads of different sizes and colors. The UV transmittance of samples was mostly dependent on the particle size, rather than the material and color of the particle. Meanwhile, the inactivation efficiency of microorganisms was affected by the particle material and color. Compared with the sample without particle addition, CB at the concentration of 1010 particles mL-1 deteriorated the inactivation efficiency of E. coli and MS2, whereas white PS enhanced it, implying a contribution of scattered UV light in the inactivation. The inactivation rate of MS2 with particles was statistically similar to that observed in samples without particle addition (p>0.05) , in spite of the quality of particle-added samples showing turbidity of 0.6–1.5 degrees, color above 13 degrees, and UV transmittance of 56–70%. This study indicates that, in the experimental conditions adopted in this study using standard particles, suspended particles in water do not necessarily interfere with UV disinfection and some particles can even enhance the efficiency by scattering UV light under certain conditions.
