Farm-to-Tap Water Treatment: Naturally-Sourced Photosensitizers for Enhanced Solar Disinfection of Drinking Water

Abstract

Universal access to basic drinking water services remains elusive, especially for rural communities of low-and lower-middle income countries where financial constraints restrict the implementation of existing drinking water development approaches. With the need for cheaper and more accessible point-of-use water treatment technologies, this study proposes a near-zero cost modification for solar disinfection (SODIS) using a suite of natural, plant-sourced photosensitizers to produce singlet oxygen and accelerate microbial inactivation under simulated sunlight. Chlorophyll, curcumin, and Saint John's Wort extract are applied with edible dispersants, enhancing the inactivation of bacteriophage MS2, a human enteric virus surrogate. Chlorophyll exhibited the most dramatic enhancement, increasing the disinfection rate up to 180 times that of SODIS alone. The potential for this approach to be successfully applied in different geographic regions was evaluated using the experimentally obtained disinfection kinetics and annual average daytime surface sunlight intensity data across the globe. The findings suggest that locally sourced natural photosensitizers and dispersants (e.g., chlorophyll extracted from alfalfa and saponin extracted from quinoa husks) can be a particularly useful point-of-use water disinfection technology for rural regions of low-and lower-middle income countries that have been previously underserved by safe water initiatives.

Natural Photosensitizers in Antimicrobial Photodynamic Therapy

“…Moreover, Saint John’s wort extract-mediated ADPT inhibited oral biofilms [ 116 ]. Saint John’s wort extract was also studied against human enteric virus under solar irradiation [ 117 ]. Giacone et al [ 118 ] studied the photodynamic effects of Tagetes minuta extracts on Candida species.…”

Polylactic Acid Filament Containing Boron-Dipyrromethene (BODIPY) for Singlet Oxygen Generation in Photoactivatable Antimicrobial Objects

“…Photoinactivation of pathogenic microbes represents a promising method for water disinfection. 63 Typically, this treatment involves adding PS to contaminated water, 64 but it poses challenges like PS solubilization, photobleaching, and potential degradation. An often overlooked issue is the difficulty in removing PS after treatment, which can have adverse health and environmental effects.…”

Traditional and Emerging Water Disinfection Technologies Challenging the Control of Antibiotic-Resistant Bacteria and Antibiotic Resistance Genes

“…Sunlight contains a broad spectrum of UV and has considerable economic benefits; as such, it is also used to inactivate microbes in water. − The mechanism by which sunlight inactivates bacteria is mainly explained by the fact that most UVB in sunlight can penetrate bacteria and reach their cytoplasm, damaging the membrane-binding proteins, cytoplasmic proteins, and genomic DNA . Zhang et al.…”