The Ulm University of Applied Sciences is investigating a technique using visible optical radiation (405 nm and 460 nm) to inactivate health-hazardous bacteria in water. A conceivable application could be point-of-use disinfection implementations in developing countries for safe drinking water supply. Another possible application field could be to provide sterile water in medical institutions like hospitals or dental surgeries where contaminated pipework or long-term disuse often results in higher germ concentrations. Optical radiation for disinfection is presently mostly used in UV wavelength ranges but the possibility of bacterial inactivation with visible light was so far generally disregarded. One of the advantages of visible light is, that instead of mercury arc lamps, light emitting diodes could be used, which are commercially available and therefore cost-efficient concerning the visible light spectrum. Furthermore they inherit a considerable longer life span than UV-C LEDs and are non-hazardous in contrast to mercury arc lamps. Above all there are specific germs, like Bacillus subtilis, which show an inactivation resistance to UV-C wavelengths. Due to the totally different deactivation mechanism even higher disinfection rates are reached, compared to Escherichia coli as a standard laboratory germ. At 460 nm a reduction of three log-levels appeared with Bacillus subtilis and a half log-level with Escherichia coli both at a dose of about 300 J/cm². With the more efficient wavelength of 405 nm four and a half log-levels are reached with Bacillus subtilis and one and a half log-level with Escherichia coli also both at a dose of about 300 J/cm². In addition the employed optical setup, which delivered a homogeneous illumination and skirts the need of a stirring technique to compensate irregularities, was an important improvement compared to previous published setups. Evaluated by optical simulation in ZEMAX® the designed optical element provided proven homogeneity distributions with maximum variation of ± 10 %.

© 2015 SPIE

PDF Article
More Like This
Detection and Identification of a Water Mixture of E. coli Cells and B. subtilis Spores with Raman Chemical Imaging Microscopy

Ashish Tripathi, Rabih E. Jabbour, Patrick J. Treado, Janet L. Jensen, and A. Peter Snyder
PWC5 Photonic Applications Systems Technologies Conference (PhAST) 2007

Direct fs-laser bacterial inactivation for a biomedical platform

C. Guerra-Olvera, V. Pérez-Laguna, and S. Camacho-López
104170I European Conference on Biomedical Optics (ECBO) 2017

Photodynamic inactivation of the models Mycobacterium phlei and Mycobacterium smegmatis in vitro

R. Bruce-Micah, U. Gamm, D. Hüttenberger, J. Cullum, and H.-J. Foth
7373_1L European Conference on Biomedical Optics (ECBO) 2009


You do not have subscription access to this journal. Citation lists with outbound citation links are available to subscribers only. You may subscribe either as an OSA member, or as an authorized user of your institution.

Contact your librarian or system administrator
Login to access OSA Member Subscription