Book Description

UV disinfection performance was investigated under the influence of representative particle sources, including wastewater particles from secondary effluent in a wastewater treatment plant, river particles from surface water, floc particles from coagulated surface water, floc particles from coagulated process water in a drinking water treatment plant, and soil particles from runoff water (planned). Low-pressure (LP) and medium-pressure (MP) UV dose-response of spiked indicator bacteria E. coli was determined using a standard collimated beam apparatus with respect to different particle sources. Significant impacts of wastewater suspended solids (3.13~4.8 NTU) agree with the past studies on UV inactivation in secondary effluents. An average difference (statistical significance level of 5% or a=5%) of the log inactivation was 1.21 for LP dose and 1.18 for MP dose. In river water, the presence of surface water particles (12.0~32.4 NTU) had no influence on UV inactivation at all LP doses. However, when the floc particles were introduced through coagulation and flocculation, an average difference (a=5%) of the log inactivation was 1.25 for LP doses and 1.12 for MP doses in coagulated river water; an average difference (a=5%) of the log inactivation was 1.10 for LP doses in coagulated process water. Chlorination was compared in parallel with UV inactivation in terms of particulate impacts. However, even floc-associated E. coli were too sensitive to carry out the chlorination experiment in the laboratory, indicating that chlorine seems more effective than UV irradiation on inactivation of particle-associated microorganisms. In addition, a comprehensive particle analysis supported the experimental results relevant to this study.