A novel, optical, on-line bacteria sensor for monitoring drinking water quality.

Bo Højris,Sarah Christine Boesgaard Christensen,Hans-Jørgen Albrechtsen,Mathis Dahlqvist,Christian Smith

doi:10.1038/srep23935

Bo Højris, Sarah Christine Boesgaard Christensen + Show 3 more

Open Access

https://doi.org/10.1038/srep23935

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Abstract

Today, microbial drinking water quality is monitored through either time-consuming laboratory methods or indirect on-line measurements. Results are thus either delayed or insufficient to support proactive action. A novel, optical, on-line bacteria sensor with a 10-minute time resolution has been developed. The sensor is based on 3D image recognition, and the obtained pictures are analyzed with algorithms considering 59 quantified image parameters. The sensor counts individual suspended particles and classifies them as either bacteria or abiotic particles. The technology is capable of distinguishing and quantifying bacteria and particles in pure and mixed suspensions, and the quantification correlates with total bacterial counts. Several field applications have demonstrated that the technology can monitor changes in the concentration of bacteria, and is thus well suited for rapid detection of critical conditions such as pollution events in drinking water.

Highlights

Today, microbial drinking water quality is monitored through either time-consuming laboratory methods or indirect on-line measurements
One of the major challenges in ensuring safe drinking water is the difference between the time it takes to produce, distribute, and consume the water, and the time it takes to investigate whether it is safe to drink[1] it
In drinking water some of the major health risks are constituted by microorganisms[2,3,4,5] either coming from the water source, entering storage or distribution systems unintendedly or growing in the water

Summary

Introduction

Microbial drinking water quality is monitored through either time-consuming laboratory methods or indirect on-line measurements. Water utilities are required to verify the water quality on a regular basis, applying standard methods at predetermined sampling frequencies These methods are typically growth-based, laborious and time-consuming, giving answers one to three days later[6] and merely providing point information without insight into temporal development. A great deal of effort has been put into the development of sensors that sense bacteria by direct contact with the sensor surface[15,16,17] These solutions are either complicated to operate, require addition of chemicals, daily or weekly maintenance, or are too expensive to be deployed throughout distribution networks. Major utilities often increase the number of analyses beyond the requirements and supplement their data with on-line measurements of turbidity, conductivity, etc.[19,20,21] Since such parameters respond to more than just bacterial content, they are likely to show false positives as well as false negatives in terms of microbiological pollution detection

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