LEDeffect – Understanding the mechanisms of inactivation of ultraviolet light emitting diodes to develop effective water disinfection systems

funded by FCT – PTDC/EAM-AMB/1561/2021

starting date: 01/03/2022

ending date: 28/02/2025

Abstract

The development of effective disinfection treatment processes will be crucial to help the water industry cope with the inevitable challenges resulting from the increase in human population and climate change. Climate change leads to heavy rainfall, flooding and hot weather events that are associated with waterborne diseases. Developing effective treatment technologies will improve our resilience to cope with these events and our capacity to safeguard public health.

Light emitting diodes recently emerged as a promising disinfection alternative to traditional UV mercury lamps. Besides being mercury free, light emitting diodes are extremely compact electronic devices with low energy demand that can be acquired with a diversity of wavelengths. Previous research showed that if we use three small light emitting diodes that emit at 265nm, wavelength closer to the peak absorption of DNA, a higher inactivation efficiency will be attained compared with if we use three small light emitting diodes that emit at 255nm, wavelength similar to what is emitted by the low pressure mercury lamps, that are widely used for water disinfection.

This project will focus on gaining a further understanding about the mechanisms of inactivation of ultraviolet light emitting diodes that emit light at different wavelengths. After understanding their mechanisms of inactivation, the goal of this project is the production of custom made light emitting diode panels that ensure higher DNA and RNA damages, affect the enzymatic activity, membrane permeability, cell wall and biological processes of the different microorganisms with no or minimum dark and light repair possibilities. The target microorganisms selected include gram-negative and gram-positive bacteria that are used as water quality indicators of fecal contamination and adenovirus due to its resistance to UV disinfection.

The custom built panels developed in this project will be tested in a novel hybrid reactor, developed by the project team, that combines membrane filtration with UV photolysis in a single treatment compartment. This hybrid treatment system can become a low-cost, environmental friendly and sustainable new advanced water treatment technology able to cope with current and future water quality disinfection challenges.

This project will deepen the knowledge on the fundamental mechanisms behind disinfection, an essential process to ensure water purification in the coming decades. The knowledge gained can be of use to many other applications when effective disinfection or the sterilization of surfaces and medical devices are needed and can thus be also of interest to food and pharmaceutical industries as well as municipalities and hospitals.

This project brings together two research groups from iBET – the Laboratory of Membrane Processes and the Laboratory of Food Safety & Microbiology and research groups from two different Institutions of Universidade Nova de Lisboa – the Control of Gene Expression Laboratory of ITQB NOVA and the Laboratory of Membrane Processes of the NOVA School of Science & Technology. The project team combines experience in the following research areas: water quality and treatment, photolysis, advanced oxidation processes, membrane filtration, thin film deposition, characterization of advanced functional materials, microbiology, molecular biology, RNA degradation mechanisms, characterization of enzymes, bacterial stress, growth and survival.

Main Contractor: Instituto de Biologia Experimental e Tecnológica (iBET)

Participating Institutions: ITQB NOVA– Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa and FCT NOVA – Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa