Near Real-Time Detection of E. coli in Reclaimed Water

Abstract

Advanced treatment of reclaimed water prior to potable reuse normally results in the inactivation of bacterial populations, however, incremental treatment failure can result in bacteria, including pathogens, remaining viable. Therefore, potential microorganisms need to be detected in real-time to preclude potential adverse human health effects. Real-time detection of microbes presents unique problems which are dependent on the water quality of the test water, including parameters such as particulate content and turbidity, and natural organic matter content. In addition, microbes are unusual in that: (i) viability and culturability are not always synonymous; (ii) viability in water can be reduced by osmotic stress; and (iii) bacteria can invoke repair mechanisms in response to UV disinfection resulting in regrowth of bacterial populations. All these issues related to bacteria affect the efficacy of real-time detection for bacteria. Here we evaluate three different sensors suitable for specific water qualities. The sensor A is an on-line, real-time sensor that allows for the continuous monitoring of particulates (including microbial contaminants) using multi-angle-light scattering (MALS) technology. The sensor B is a microbial detection system that uses optical technique, Mie light scattering, for particle sizing and fluorescence emission for viable bacteria detection. The last sensor C was based on adenosine triphosphate (ATP) production. E. coli was used a model organism and out of all tested sensors, we found the sensor C to be the most accurate. It has a great potential as a surrogate parameter for microbial loads in test waters and be useful for process control in treatment trains.

Use of an Artificial Miniaturized Enzyme in Hydrogen Peroxide Detection by Chemiluminescence

“…Future efforts will be devoted to enhance the performances of FeMC6*a in luminol-based H 2 O 2 determination either by using enhancers or immobilization onto solid supports [ 16 , 19 , 23 , 25 , 30 , 31 , 64 ], and to the construction of a standalone sensor device. Process control and quality assessment of reclaimed water may be further improved by developing efficient multi-purpose devices [ 4 , 28 ]. In particular, different oxidants, other than hydrogen peroxide, such as chlorite and chlorine dioxide [ 70 ], may be revealed through the methodology developed here, and their consumption rate may be eventually coupled to the presence of several aromatic and organophosphate pollutants [ 71 , 72 , 73 ].…”

“…In this context, water reclamation for potable reuse is nowadays considered a necessary approach to face near-future water scarcity. Among the chemical, physical, and biological treatments to which reclaimed water must be subjected, advanced oxidation processes (AOPs), coupling either UV irradiation or ozonation in the presence of hydrogen peroxide, are effective both in microbial sterilization and organic pollutant oxidative degradation [ 4 , 5 , 6 ]. Hydrogen peroxide determination is, therefore, crucial in: (i) Assessing the undesired residual peroxide concentration of the final treated water; (ii) monitoring, hopefully on a real-time basis, the process performance; (iii) tuning the reagent amount in order to get the best results in terms of its ecological and economic costs.…”

Rapid Detection Methods for Bacterial Pathogens in Ambient Waters at the Point of Sample Collection: A Brief Review

“…Besides miniature cell cultivation and FCM, other online cell-based sensing methods have also been developed. A real-time sensor using multiangle light scattering (MALS) technology was developed by Sherchan et al By comparing the light scattering patterns after using a laser beam to strike particulates in water (including organic particles and microbial cells) with light scattering patterns in the computerized database, data obtained was characterized and the load of injected Escherichia coli was back-calculated [ 20 ]. Due to the existence of fluorophores in bacterial cells such as tryptophan, phenylalanine, or nucleic acids, which emit fluorescence light after excited by ultraviolet light, Simões and Dong developed an optical microfluidic sensor based on tryptophan intrinsic fluorescence with 3D-printing prototyping [ 21 ].…”

Enabling Multi-Site Stormwater Environmental Compliance Approvals in Ontario, Canada

“…Developments in electrochemical biosensors have advanced in the medical and food safety industry (Settu et al 2013). In 2018, Parmiss Mojir Shaibani and Amirreza Sohrabi from the University of Calgary appeared to develop an electrochemical sensor that analyzes the metabolic activity of E.coli (Sherchan et al 2018). These recent developments provide optimism that a real-time E.coli sensor will be available in the coming years.…”