Advances in quantifying microbial contamination in potable water: Potential of fluorescence‐based sensor technology

Abstract

Improved monitoring of potable water is essential if we are to achieve the UN Sustainable Development Goals (SDGs), specifically SDG6: to make clean water and sanitation available to all. Typically monitoring of potable water requires laboratory analysis to detect indicators of fecal pollution, such as thermotolerant coliforms (TTCs), Escherichia coli (E. coli), or intestinal enterococci. However, these analyses are time‐consuming and expensive, and recent advances in field deployable sensing technology offer opportunities to investigate both the spatial and temporal dynamics of microbial pollution in a more resolved and cost‐effective manner, thus advancing process‐based understanding and practical application for human health. Fluorescence offers a realistic proxy for monitoring coliforms in freshwaters with potential for quantification of potable water contamination in near real‐time with no need for costly reagents. Here, we focus on E. coli to provide a state‐of‐the‐art review of potential technologies capable of delivering an effective real‐time E. coli sensor system. We synthesize recent research on the use of fluorescence spectroscopy to quantify microbial contamination and discuss a variety of approaches (and constraints) to relate the raw fluorescence signal to E. coli enumerations. Together, these offer an invaluable platform to monitor drinking water quality which is required in situations where the water treatment and distribution infrastructure is degraded, for example in less economically developed countries; and during disaster‐relief operations. Overall, our review suggests that the fluorescence of dissolved organic matter is the most viable current method—given recent advances in field‐deployable technology—and we highlight the potential for recent developments to enhance approaches to water quality monitoring. This article is categorized under: Engineering Water > Water, Health, and Sanitation Engineering Water > Methods Human Water > Methods

Blockchain Technology and Sanitary Aspects of the Water Supply

“…Other real-time methods for faecal contamination use ATF monitoring (Højris et al,2018) or other metabolites, like tryptophan, by in-situ tryptophan-like fluorescence (Sorensen et al, 2018). Various biosensors use fluorescent-labelled, fluorogenic, immunomagnetic and radio-labelled antibodies or antigens and other proteins, such as enzymes, cell structures or organisms (Gunter et al, 2023). Biosensors are usually electrochemical, optical or fluorescent.…”

In-situ optical water quality monitoring sensors—applications, challenges, and future opportunities

“…Fluorescence has also been used to quantify DOC and BOD (Khamis et al, 2017(Khamis et al, , 2021 by measuring dual fluorescence peaks (tryptophan and humic-like fluorescence) and turbidity, which is vital for developing reliable proxy models. There has also been growing interest in using fluorescence to quantify microbial contamination in rivers (Baker et al, 2015;Bridgeman et al, 2015), groundwater (Nowicki et al, 2019;Sorensen et al, 2020;Dapkus et al, 2023), and potable water (Sorensen et al, 2018;Gunter et al, 2023). However, it is important to note that most studies to date focus on single or dual fluorescence peaks; hence, the associated models tend to be relatively simple compared to those developed for absorbance sensors.…”

“…Several review papers have summarized recent advances in water quality monitoring (Raich, 2013;Banna et al, 2014;Gholizadeh et al, 2016;Thakur and Devi, 2022;Zainurin et al, 2022;Zaidi Farouk et al, 2023), and while some have focused explicitly on in-situ optical sensors (Hudson et al, 2007;Carstea et al, 2016Carstea et al, , 2020Gunter et al, 2023), there is still a need for deeper understanding of this rapidly evolving technology and its potential for water quality monitoring at different scales. In this review, we provide a concise overview of the current and future challenges in in-situ optical monitoring of freshwater and marine bodies, focusing on fluorescence, full-spectrum absorbance, scattering and reflectance-based techniques.…”

Low-Cost Water Quality Sensors for IoT: A Systematic Review

“…The parameters of WQI-ANA are measured in situ with a multiparametric device and at the laboratory by taking water samples to analyze mainly BOD, coliforms, total solids, and total nitrogen and phosphorus. There is the development of multiparameter probes including BOD and coliform bacteria sensors [24][25][26], but there are yet challenges to validate them. The common practice is to measure these parameters in the water samples and, when feasible, also in other types of samples.…”