Actinometric and biodosimetric evaluation of UV-C dose delivery in annular, Taylor–Coutte and coiled tube continuous systems

Abstract

In this study, the evaluation of the performance of two thin-film UV-C reactors (annular and Taylor-Couette) and a coiled tube system is presented using actinometry and biodosimetry methods. The iodide/iodate actinometry method was found suitable for comparison of the efficiency of UV-C dose delivery of the UV-C continuous flow systems. Inactivation kinetics of Escherichia coli ATCC 8739 in quarter-strength Ringer's solution (absorption coefficient α ∼ 0 cm) at various flow conditions at Reynolds numbers in the range of 26 to 3000 showed a good correlation between the different reactor types. In high UV-C absorbing liquids, the inactivation efficiency increases due to the improved radial mixing. The inactivation performance of the Taylor-Couette system correlates to the annular reactor when no rotation force is applied. The residence time distributions showed the narrowest distribution with the coiled tube system at comparable flow rates. The results indicate that, despite the laminar flow conditions, the performance of the Taylor-Couette unit becomes equal to the turbulent flow conditions of the coiled tube reactor by rotation of the inner cylinder.

Taylor‐Couette reactor: Principles, design, and applications

“…When a coiled tube system was used (whose RTD was narrower), the latter showed better microbial reduction than the aforementioned thin film systems. However, in spite of the laminar flow conditions, the reactor performance of the TCR upon rotation of the inner cylinder is comparable to that of the coiled tube under turbulent flow 109 . Prior to these findings, TCRs had already been used in other continuous disinfection processes using UV radiation 110,111 .…”

A practical bacterial biodosimetry procedure to assess performance of lab-scale flow-through ultraviolet water disinfection reactors

“…As a consequence, a range of different methods for biodosimetry using microbial cells as challenge organism have been applied to lab-scale reactors (3,(21)(22)(23)(24)(25)(26)(27)(28)(29). However, the parameters for these vary and are not well defined, ranging from flow-through to batch systems with or without recirculation, a range of species in different conditions and feed solutions, varying washing steps and with or without inclusion of photo repair of microorganism (3,(21)(22)(23)(24)(25)(26)(27)(28)(29).…”

“…However, the parameters for these vary and are not well defined, ranging from flow-through to batch systems with or without recirculation, a range of species in different conditions and feed solutions, varying washing steps and with or without inclusion of photo repair of microorganism (3,(21)(22)(23)(24)(25)(26)(27)(28)(29). There are many steps involved in biodosimetry that can be critical, including cultivation, washing, the design of the experiment, and processing of the samples including measures for or against repair mechanisms (3,(21)(22)(23)(24)(25)(26)(27)(28)(29). However, as the methodology is not yet standardized, results may largely differ between studies.…”

“…However, as the methodology is not yet standardized, results may largely differ between studies. Furthermore, most studies focused on nosocomial bacteria or model organism such as Escherichia coli (3,(21)(22)(23)(24)(25)(26)(27)(28)(29), which are not relevant in technical applications that are affected by biofouling. Biofouling of membranes is caused by biofilm-forming, usually non-infectious, non-model organism, which to our knowledge have not been used as challenge organism, yet.…”

Performance of combined technologies for the inactivation of Saccharomyces cerevisiae and Escherichia coli in pomegranate juice: The effects of a continuous‐flow UV‐Microwave system

“…During the last decade, UVC light treatments have been successfully applied for the pasteurization of liquid foods, such as wine, milk, and many juices (Cilliers et al, 2014; Rizzotti, Levav, Fracchetti, Felis, & Torriani, 2015), keeping their sensorial properties and guaranteeing their shelf life (Karim, Shamsudin, Rahman, & Adzahan, 2016; López‐Malo & Palou, 2005). However, most findings suggest that multiple lamps are required for effective disinfection (Müller et al, 2017).…”