Impact of Particles on Uv Disinfection of Water and Wastewater Effluents: A Review

Abstract

Particles in water sources may be classified in various groups such as living vs. non-living, nano vs. sub-micron to micron sized and mineral vs. organic. Living particles for example comprise of bacteria, viruses, protozoa and algae while non-living particles include mineral particles, organic particles, cell debris and macromolecules. Particles in water sources may be dispersed as single entities or associated with multiple particles in floes or aggregates. Particles may be further characterized by their chemical nature, size distribution, density, absorbance, scattering and typical gross measurements such as turbidity and suspended solids. Although ultraviolet (UV) irradiation is principally accepted as a primary disinfection technology for use in water and wastewater effluent, still research is needed to understand the extent to which particles in water may hinder the UV treatment efficacy by interacting with microbial pathogens. Both of the phenomena: (1) particles physically associated with microorganisms in a clump or aggregate and (2) particles not physically associated with microorganisms however interact by shielding, absorbing, scattering or blocking UV light, are integrated in the term "particle-microbe interactions". This review covers the impact of the interaction between microorganisms (mainly bacteria) which are the target for UV disinfection and particles in water and wastewater effluents on the efficacy of UV disinfection.

The question of pathogen quantification in disinfected graywater

“…cleanliness of the quartz sleeve), the sensitivity of the pathogens to UV radiation, and the treated water quality. For example, UV disinfection efficiency is sensitive to TSS, color and organic matter in the disinfected water (Mamane, 2008). In the field, these parameters can change over time, likely resulting in changing disinfection efficiency (Supplementary information: GW quality and disinfection).…”

Mercury-free sources of VUV/UV radiation: application of modern excimer lamps (excilamps) for water and air treatment

“…Quantum efficiencies or rate constants [14] 19] CO + ·OH −→ CO 2 + H· 1.5 × 10 −13 6.7 × 10 −14 cm 3 molecule −1 s −1 b [20] H· + ·H −→ H 2 8.1 × 10 −33 cm 6 molecule −2 s −1 e a Bolton and Cater (1994). b At 298 K, see Atkinson et al (1991Atkinson et al ( -1992.…”

“…Several relevant gas-phase photoreactions are collected in eqs. [14]- [20] ( Table 3). They also include eqs.…”

“…Hydrogen atoms recombine with formation of molecular hydrogen according to eq. [20] (Table 3). Traces of methane and at lower flow rates (20 L h −1 ) significant amounts of molecular hydrogen could be detected by GC (sometimes leading to fizzling explosions within the excilamp).…”

UV treatment efficiency for E. coli in storm water containing different size fractions of suspended solids

“…The mechanism for UV disinfection transfers electromagnetic energy, typically from a mercury arc lamp, to the genetic material (DNA and RNA) present in pathogens (bacteria, viruses, etc.). The "germicidal range" of the UV spectrum, or the portion of the spectrum which is effective in UV disinfection, is 200-300nm [7]. Because UV radiation impacts the genetic material, an effective dose of UV radiation renders the organism no longer capable of reproducing, despite cell membranes and enzymes remaining relatively intact [8].…”