LED revolution: fundamentals and prospects for UV disinfection applications

The UV-light emitting diode (LED) has been attracting significant attention as a new UV source that can replace conventional mercury gas-filled lamps in water disinfection applications. However, the UV-LED remains a relatively new addition to the water treatment toolbox. The current lack of fundamental understanding risks underutilizing uniquely advantageous features of the UV-LED due to unguided design and non-optimized disinfection practices. Our review presents the necessary fundamental knowledge required for the successful implementation of UV-LEDs, including the mechanism of light generation, LED chip fabrication, package design, and essential properties of UV-LEDs. We introduce distinct advantages, such as wavelength tuning, control of radiation patterns, and array design, while emphasizing the significant differences between LED and mercury lamp technologies required to achieve successful technology transfer. Previous studies investigated the design of UV-LED disinfection systems; however, little consensus has yet emerged regarding the integration of LEDs into flow-through reactors. While UV-LED disinfection systems will undisputedly mature in the near future, environmental engineers face a number of urgent research needs in this area including heat sink design, radiation pattern and array design optimization for uniform UV dose delivery, targeted pathogen-wavelength considerations, improved light extraction, and component monitoring systems.

[1]  Fariborz Taghipour,et al.  Application of ultraviolet light-emitting diodes (UV-LEDs) for water disinfection: A review. , 2016, Water research.

[2]  K. Linden,et al.  UV disinfection implementation status in US water treatment plants , 2012 .

[3]  Y. Habtemichael.  Packaging designs for ultraviolet light emitting diodes , 2012 .

[4]  M. Tvede,et al.  Disinfection of Pseudomonas aeruginosa biofilm contaminated tube lumens with ultraviolet C light emitting diodes , 2010, Biofouling.

[5]  Harald Ries,et al.  Tailored freeform optical surfaces. , 2002, Journal of the Optical Society of America. A, Optics, image science, and vision.

[6]  K. Linden,et al.  Comparative effectiveness of UV wavelengths for the inactivation of Cryptosporidium parvum oocysts in water. , 2001, Water science and technology : a journal of the International Association on Water Pollution Research.

[7]  Michael Wraback,et al.  270 nm Pseudomorphic Ultraviolet Light-Emitting Diodes with Over 60 mW Continuous Wave Output Power , 2013 .

[8]  V. Adivarahan,et al.  Ohmic Contact to High-Aluminum-Content AlGaN Epilayers , 2009 .

[9]  A. Cabaj,et al.  Time dose reciprocity in UV disinfection of water , 1998 .

[10]  N. Holonyak,et al.  COHERENT (VISIBLE) LIGHT EMISSION FROM Ga(As1−xPx) JUNCTIONS , 1962 .

[11]  Michael S. Shur,et al.  Large Chip High Power Deep Ultraviolet Light-Emitting Diodes , 2010 .

[12]  William A. Parkyn.  Design of illumination lenses via extrinsic differential geometry , 1998, Optics & Photonics.

[13]  Toru Kinoshita,et al.  Performance and Reliability of Deep-Ultraviolet Light-Emitting Diodes Fabricated on AlN Substrates Prepared by Hydride Vapor Phase Epitaxy , 2013 .

[14]  Atsuhiro Kinoshita,et al.  Marked enhancement of 320–360 nm ultraviolet emission in quaternary InxAlyGa1−x−yN with In-segregation effect , 2002 .

[15]  J. Schoenung,et al.  Potential environmental impacts of light-emitting diodes (LEDs): metallic resources, toxicity, and hazardous waste classification. , 2011, Environmental science & technology.

[16]  Michael Kneissl,et al.  Improved injection efficiency in 290 nm light emitting diodes with Al(Ga)N electron blocking heterostructure , 2013 .

[17]  R. Simons,et al.  Optical fluence modelling for ultraviolet light emitting diode-based water treatment systems. , 2014, Water research.

[18]  Norihiko Kamata,et al.  222–282 nm AlGaN and InAlGaN‐based deep‐UV LEDs fabricated on high‐quality AlN on sapphire , 2009 .

[19]  Mika Sillanpää,et al.  Ultraviolet light-emitting diodes in water disinfection , 2009, Environmental science and pollution research international.

[20]  Robert F. Karlicek,et al.  Growth of InGaN/GaN multiple-quantum-well blue light-emitting diodes on silicon by metalorganic vapor phase epitaxy , 1999 .

[21]  M. Craford,et al.  Status and Future of High-Power Light-Emitting Diodes for Solid-State Lighting , 2007, Journal of Display Technology.

[22]  Hans-Joachim Mosler,et al.  Solar water disinfection (SODIS): a review from bench-top to roof-top. , 2012, Journal of hazardous materials.

[23]  N. Ashbolt,et al.  Photovoltaic powered ultraviolet and visible light-emitting diodes for sustainable point-of-use disinfection of drinking waters. , 2014, The Science of the total environment.

[24]  B. Coulomb,et al.  Effect of coupled UV-A and UV-C LEDs on both microbiological and chemical pollution of urban wastewaters. , 2012, The Science of the total environment.

[25]  Yoon-Kyu Song,et al.  AlGaN/GaN quantum well ultraviolet light emitting diodes , 1998 .

[26]  J. Pérez,et al.  Low cost UVA-LED as a radiation source for the photo-Fenton process: a new approach for micropollutant removal from urban wastewater , 2017 .

[27]  R. Rice,et al.  Ultraviolet Light in Water and Wastewater Sanitation , 2002 .

[28]  Max Shatalov,et al.  Heuristic optimization of a continuous flow point-of-use UV-LED disinfection reactor using computational fluid dynamics. , 2015, Water research.

[29]  Wim S. J. Uijttewaal,et al.  Evaluation of experimental techniques to validate numerical computations of the hydraulics inside a UV bench-scale reactor , 2010 .

[30]  G. Bratbak,et al.  Effects of ultraviolet radiation on marine virus-phytoplankton interactions. , 2003, FEMS microbiology ecology.

[31]  Joel J. Ducoste,et al.  Alternative Approaches to Modeling Fluence Distribution and Microbial Inactivation in Ultraviolet Reactors: Lagrangian versus Eulerian , 2005 .

[32]  Masatake Akutagawa,et al.  Development of a new water sterilization device with a 365 nm UV-LED , 2007, Medical & Biological Engineering & Computing.

[33]  Liu Xu,et al.  Freeform surface lens for LED uniform illumination. , 2009, Applied optics.

[34]  J. Bolton,et al.  Comparison of the action spectra and relative DNA absorbance spectra of microorganisms: information important for the determination of germicidal fluence (UV dose) in an ultraviolet disinfection of water. , 2009, Water research.

[35]  Ernest R. Blatchley,et al.  Numerical modelling of UV intensity : application to collimated-beam reactors and continuous-flow systems , 1997 .

[36]  Ivan Moreno,et al.  Modeling the radiation pattern of LEDs. , 2008, Optics express.

[37]  Marc Schiler.  Simplified Design of Building Lighting , 1992 .

[38]  Richard M Jenny,et al.  Modeling a continuous flow ultraviolet Light Emitting Diode reactor using computational fluid dynamics , 2014 .

[39]  Regina Sommer,et al.  Spectral sensitivity of Bacillus subtilis spores and MS2 coliphage for validation testing of ultraviolet reactors for water disinfection. , 2005, Environmental science & technology.

[40]  K. Linden,et al.  Action spectra for validation of pathogen disinfection in medium-pressure ultraviolet (UV) systems. , 2015, Water research.

[41]  E. Schubert,et al.  Analysis of high-power packages for phosphor-based white-light-emitting diodes , 2005 .

[42]  Joel Ducoste,et al.  Microbial UV fluence-response assessment using a novel UV-LED collimated beam system. , 2011, Water research.

[43]  T. S. Perry.  M. George Craford [biography] , 1995 .

[44]  S. Takizawa,et al.  Application of UV light emitting diodes to batch and flow-through water disinfection systems , 2013 .

[45]  Yi Luo,et al.  Discontinuous free-form lens design for prescribed irradiance. , 2007, Applied optics.

[46]  Jannick P Rolland,et al.  Fast freeform reflector generation usingsource-target maps. , 2010, Optics express.

[47]  Xu Liu,et al.  Freeform LED lens for uniform illumination. , 2008, Optics express.

[48]  M. Asif Khan,et al.  Continuous Wave Milliwatt Power AlGaN Light Emitting Diodes at 280 nm , 2004 .

[49]  Robert H. Bishop.  The Mechatronics Handbook - 2 Volume Set , 2002 .

[50]  Michael Kneissl,et al.  III-Nitride Ultraviolet Emitters: Technology and Applications , 2015 .

[51]  M. Asif Khan,et al.  III–Nitride UV Devices , 2005 .

[52]  Yi Luo,et al.  Design of compact and smooth free-form optical system with uniform illuminance for LED source. , 2010, Optics express.

[53]  Isamu Akasaki,et al.  Stimulated Emission Near Ultraviolet at Room Temperature from a GaN Film Grown on Sapphire by MOVPE Using an AlN Buffer Layer , 1990 .

[54]  Grigory Simin,et al.  Milliwatt power deep ultraviolet light-emitting diodes over sapphire with emission at 278 nm , 2002 .

[55]  F. Ferrini,et al.  Municipal-treated wastewater reuse for plant nurseries irrigation. , 2004, Water research.

[56]  S. Keller,et al.  1 - 8-GHz GaN-based power amplifier using flip-chip bonding , 1999, IEEE Microwave and Guided Wave Letters.

[57]  C. Yost,et al.  Point-of-use water disinfection using UV light-emitting diodes to reduce bacterial contamination , 2013, Environmental Science and Pollution Research.

[58]  Brendan J. Howlin,et al.  Studies of cure schedule and final property relationships of a commercial epoxy resin using modified imidazole curing agents , 1998 .

[59]  E. Fred Schubert,et al.  Light-Emitting Diodes , 2003 .

[60]  Gustaaf Borghs,et al.  40% efficient thin-film surface-textured light-emitting diodes by optimization of natural lithography , 2000 .

[61]  J. Cadet,et al.  Direct and indirect effects of UV radiation on DNA and its components. , 2001, Journal of photochemistry and photobiology. B, Biology.

[62]  Michael Kunzer,et al.  Fabrication and characterization of GaN/InGaN/AlGaN double heterostructure LEDs and their application in luminescence conversion LEDs , 1999 .

[63]  M. Asif Khan,et al.  250nmAlGaN light-emitting diodes , 2004 .

[64]  Shicheng Zhang,et al.  CFD modeling of a UV-LED photocatalytic odor abatement process in a continuous reactor. , 2012, Journal of hazardous materials.

[65]  Takashi Mukai,et al.  High-Power GaN P-N Junction Blue-Light-Emitting Diodes , 1991 .

[66]  Mark D. Sobsey,et al.  Managing Water in the Home: Accelerated Health Gains from Improved Water Supply , 2002 .

[67]  Xu Liu,et al.  Freeform illumination design: a nonlinear boundary problem for the elliptic Monge-Ampére equation. , 2013, Optics letters.

[68]  Young-June Choi,et al.  The effects of UV disinfection on drinking water quality in distribution systems. , 2010, Water research.

[69]  Michael R. Krames,et al.  High-power AlGaInN flip-chip light-emitting diodes , 2001 .

[70]  R. Nahory,et al.  Efficient GaAs1−xSbx/AlyGa1−yAs1−xSbx double heterostructure LED’s in the 1‐μm wavelength region , 1975 .

[71]  H. Hirayama,et al.  Room-temperature operation at 333 nm of Al0.03Ga0.97N/Al0.25Ga0.75N quantum-well light-emitting diodes with Mg-doped superlattice layers , 2000 .

[72]  Toru Kinoshita,et al.  Light extraction enhancement of 265 nm deep-ultraviolet light-emitting diodes with over 90 mW output power via an AlN hybrid nanostructure , 2015 .

[73]  Minseok Ha.  Thermal analysis of high power led arrays , 2009 .

[74]  A. Scherer,et al.  30% external quantum efficiency from surface textured, thin‐film light‐emitting diodes , 1993 .

[75]  Hideki Hirayama,et al.  Realization of high-efficiency deep-UV LEDs using transparent p-AlGaN contact layer , 2013 .

[76]  J. Rose,et al.  Inactivation of bacteria, virus and Cryptosporidium by a point-of-use device using pulsed broad spectrum white light , 2000 .

[77]  Paul C.-P. Chao,et al.  Design of a novel LED lens cap and optimization of LED placement in a large area direct backlight for LCD-TVs , 2006, SPIE Photonics Europe.

[78]  E. T. Arakawa,et al.  Optical and dielectric properties of DNA in the extreme ultraviolet , 1974 .

[79]  H. Hirayama,et al.  Efficient 230–280 nm emission from high-Al-content AlGaN-based multiquantum wells , 2002 .

[80]  Hideki Hirayama,et al.  Quaternary InAlGaN-based high-efficiency ultraviolet light-emitting diodes , 2005 .

[81]  P. Mccubbin,et al.  Pulsed UV‐C Disinfection of Escherichia coli With Light‐Emitting Diodes, Emitted at Various Repetition Rates and Duty Cycles , 2013, Photochemistry and photobiology.

[82]  Asif Khan,et al.  Ultraviolet light-emitting diodes based on group three nitrides , 2008 .

[83]  C. Meulemans.  The Basic Principles of UV–Disinfection of Water , 1987 .

[84]  David G. Pelka,et al.  Free-form illumination lenses designed by a pseudo-rectangular lawnmower algorithm , 2006, SPIE Optics + Photonics.

[85]  W. Kowalski.  Ultraviolet Germicidal Irradiation Handbook: UVGI for Air and Surface Disinfection , 2009 .

[86]  Michael Wraback,et al.  High Output Power from 260 nm Pseudomorphic Ultraviolet Light-Emitting Diodes with Improved Thermal Performance , 2011 .

[87]  Takashi Mukai,et al.  High-output-power deep ultraviolet light-emitting diode assembly using direct bonding , 2016 .

[88]  B. Coulomb,et al.  Multivariate optimization of fecal bioindicator inactivation by coupling UV-A and UV-C LEDs , 2012 .

[89]  T. S. Tan,et al.  High-power truncated-inverted-pyramid (AlxGa1−x)0.5In0.5P/GaP light-emitting diodes exhibiting >50% external quantum efficiency , 1999 .

[90]  Naoki Kobayashi,et al.  Efficient and high-power AlGaN-based ultraviolet light-emitting diode grown on bulk GaN , 2001 .

[91]  S. Takizawa,et al.  Effects of Arrangement of UV Light‐Emitting Diodes on the Inactivation Efficiency of Microorganisms in Water , 2016, Photochemistry and photobiology.

[92]  Nadarajah Narendran,et al.  Spectral and luminous efficacy change of high-power LEDs under different dimming methods , 2006, SPIE Optics + Photonics.

[93]  T. Xu,et al.  Vanadium-based Ohmic contacts to n-AlGaN in the entire alloy composition , 2007 .

[94]  Takashi Mukai,et al.  High-output-power 255/280/310 nm deep ultraviolet light-emitting diodes and their lifetime characteristics , 2014 .

[95]  K. Nelson,et al.  Sunlight-mediated inactivation of MS2 coliphage via exogenous singlet oxygen produced by sensitizers in natural waters. , 2007, Environmental science & technology.

[96]  H. Amano,et al.  P-Type Conduction in Mg-Doped GaN Treated with Low-Energy Electron Beam Irradiation (LEEBI) , 1989 .

[97]  M. H. Rasoulifard,et al.  Performance of the light-emitting-diodes in a continuous photoreactor for degradation of Direct Red 23 using UV-LED/S2O82− process , 2015 .

[98]  M. Asif Khan,et al.  High-efficiency 269 nm emission deep ultraviolet light-emitting diodes , 2004 .

[99]  Karl Linden,et al.  Demonstration and evaluation of germicidal UV-LEDs for point-of-use water disinfection. , 2010, Journal of water and health.

[100]  Michael S. Shur,et al.  AlGaN Deep-Ultraviolet Light-Emitting Diodes with External Quantum Efficiency above 10% , 2012 .

[101]  H. Amano,et al.  Metalorganic vapor phase epitaxial growth of a high quality GaN film using an AlN buffer layer , 1986 .

[102]  Takashi Mukai,et al.  High-power UV InGaN/AlGaN double-heterostructure LEDs , 1998 .

[103]  D Michaelis,et al.  Cartesian oval representation of freeform optics in illumination systems. , 2011, Optics letters.

[104]  A. Uhl,et al.  Optical power outputs, spectra and dental composite depths of cure, obtained with blue light emitting diode (LED) and halogen light curing units (LCUs) , 2002, British Dental Journal.

[105]  Norihiko Kamata,et al.  Recent progress and future prospects of AlGaN-based high-efficiency deep-ultraviolet light-emitting diodes , 2014 .

[106]  Jochen Stollenwerk,et al.  Algorithm for irradiance tailoring using multiple freeform optical surfaces. , 2012, Optics express.

[107]  M Jekel,et al.  Application of GaN-based ultraviolet-C light emitting diodes--UV LEDs--for water disinfection. , 2011, Water research.

[108]  M. Kurouchi,et al.  Inactivation of Bacterial Viruses in Water Using Deep Ultraviolet Semiconductor Light-Emitting Diode , 2011 .

[109]  L. Cavalieri,et al.  The Ultraviolet Absorption Spectra of Pyrimidines and Purines1 , 1950 .

[110]  Y. Taniyasu,et al.  An aluminium nitride light-emitting diode with a wavelength of 210 nanometres , 2006, Nature.

[111]  K. Linden,et al.  Enhanced UV Inactivation of Adenoviruses under Polychromatic UV Lamps , 2007, Applied and Environmental Microbiology.

[112]  Akira Takahashi,et al.  New water disinfection system using UVA light‐emitting diodes , 2007, Journal of applied microbiology.

[113]  A. Rauth.  The Physical State of Viral Nucleic Acid and the Sensitivity of Viruses to Ultraviolet Light. , 1965, Biophysical journal.

[114]  Karl G. Linden,et al.  Standardization of Methods for Fluence (UV Dose) Determination in Bench-Scale UV Experiments , 2003 .

[115]  Kuang-Lung Huang,et al.  Freeform lens design for LED collimating illumination. , 2012, Optics express.

[116]  Xiaobo Sharon Hu,et al.  Deep ultraviolet light‐emitting diodes , 2006 .

[117]  A. A. Bergh,et al.  Light-emitting diodes , 1972 .

[118]  E. Schubert,et al.  Strongly Enhanced Phosphor Efficiency in GaInN White Light-Emitting Diodes Using Remote Phosphor Configuration and Diffuse Reflector Cup , 2005 .