Dielectric Barrier Discharge based Mercury-free plasma UV-lamp for efficient water disinfection

Ram Prakash,U N Pal,Afaque M Hossain,M Krishna Mohan,N Kumar,K Khairnar

doi:10.1038/s41598-017-17455-2

Abstract

A structurally simple dielectric barrier discharge based mercury-free plasma UV-light source has been developed for efficient water disinfection. The source comprises of a dielectric barrier discharge arrangement between two co-axial quartz tubes with an optimized gas gap. The outer electrode is an aluminium baked foil tape arranged in a helical form with optimized pitch, while the inner electrode is a hollow aluminium metallic rod, hermetically sealed. Strong bands peaking at wavelengths 172 nm and 253 nm, along with a weak band peaking at wavelength 265 nm have been simultaneously observed due to plasma radiation from the admixture of xenon and iodine gases. The developed UV source has been used for bacterial deactivation studies using an experimental setup that is an equivalent of the conventional house-hold water purifier system. Deactivation studies for five types of bacteria, i.e., E. coli, Shigella boydii, Vibrio, Coliforms and Fecal coliform have been demonstrated with 4 log reductions in less than ten seconds.

Highlights

Safe drinking water is the basic need of all human beings
We have engineered an optimized dielectric discharge based mercury-free VUV/UV light source with a novel structural design that produces strong spectral bands peaking at wavelengths 253 nm and 172 nm along with a weak band peaking at wavelength 265 nm, that has been tested on a few representative bacteria to show its usefulness for efficient water sterilization
As a first step a mercury-free plasma (MFP)UV-lamp has been developed in a coaxial DBD

Summary

Introduction

Safe drinking water is the basic need of all human beings. Water that is naturally available is generally impure and contaminated with bacteria, viruses, salts and various organic compounds. We have engineered an optimized dielectric discharge based mercury-free VUV/UV light source with a novel structural design that produces strong spectral bands peaking at wavelengths 253 nm and 172 nm along with a weak band peaking at wavelength 265 nm, that has been tested on a few representative bacteria to show its usefulness for efficient water sterilization. This invention alleviates most of the problems of contemporary mercury lamps by virtue of its unique design and the composition of active discharge elements. As a result it is able to produce the desired VUV/UV wavelengths for the deactivation of bacteria in water very efficiently –without the use of toxic mercury

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Conclusion