An In-Line UV Disinfection System

NU 2009-001

Inventors

Wei Zhang

Aaron Packman*

Tadas Sileika

Short Description

A self-enclosed UV disinfection unit that includes a series of capillary tubes in a reflective housing with a UV source

Abstract

The UV disinfection unit is positioned in-line with inflow/outflow tubing of a circulating flow system, so as to provide flow-through disinfection without disrupting flow. Single-pass efficiencies are high since the glass capillaries are very thin and transparent to UV light. Multiple passes can be used to achieve even higher killing efficiency.

The UV disinfection system is shown in Figure 1 below.

The invention won the Peter Gilbert Poster Award for Excellence in Innovation and Biofilm Control.

Applications

• In-line disinfection for small-volume flow systems
• Disinfection of suspended material
• Regulation/prevention of biofilm growth

Stage of Development

• Results from an earlier version of the UV disinfection unit show that bacteria abundance clearly decreased after a single passage through the unit under flow rates as high as 0.4 ml/min. When the influent bacteria concentration was below 3.5 x 103 CUFs/ml, all bacteria were killed.
• Two continuous experiments were run in parallel, one with the UV disinfection unit and a negative control with no such unit. Figure 2 shows results for four (4) different initial concentrations of inoculated cells. Killing was very efficient in all cases, with 100% killing found for influent concentrations on the order of 103 – 104 CFU/ml. After 5 days, bacterial growth was detected in the control, producing visible biofilm growth and clogging inside the upstream tubing. On the other hand, no bacterial growth was detected upstream of the UV system after eleven days of continuous operation.
• The most recent version of the UV disinfection unit uses laser-cut mirrored acrylic to increase disinfection efficiency. Stray UV light is allowed to reflect and propagate back through the capillary tubing, which further increases unit efficiency. A limited number of units can be provided.

Publication

Packman A, Zhang W, Sileika T, Liu Y, and Chen C (2009) 'Interplay between environmental gradients and biofilm growth,' 5th ASM Conference on Biofilms.

IP Status

Issued US Patent No. 8,653,481

Figure 1 Photos of the UV disinfection system

Figure 2 Impact of UV system on bacterial abundance