Why is it Important?
Coliforms are widely monitored for both environmental, legislative and public health reasons:
Challenges to monitoring coliforms
There are numerous issues associated with the laboratory procedure for quantification of coliform counts:
It is clear that a move from traditional laboratory testing to in-situ (real-time) monitoring would help to alleviate most of the problems outlined above. It would particularly improve spatial temporal resolution of monitoring that would be directly beneficial to basin managers, water companies and legislators alike.
Proteus - the real-time solution for coliform monitoring
Figure 1. Image of the Proteus for coliform analysis.
The Proteus is a new product providing users with a robust, repeatable, low maintenance sensor platform for measuring coliforms in real-time. The Proteus is underpinned by comprehensive research exploring the use of in-situ fluorescence as a technique for real-time coliform measurement. The Proteus is a multi-parameter instrument that can incorporate a range of optical sensors. The configuration for microbial monitoring includes a tryptophan-like fluorescence (TLF) sensor, turbidity sensor (see Fig. 2) and thermistor which provides users a real time measurement of total coliforms, negating the need for the standard laboratory analysis. Using a robust correction algorithm the tryptophan signal is corrected, in real time, for known interferrants. The result is a repeatable and highly accurate measurement that can provide instantaneous coliform measurements.
Figure 2. Optical configuration of the Proteus for coliform measurement with a schematic of the measurement set up (left) and the tryptophan like fluorescence (TLF) measurement region highlighted in optical space (right).
Figure 3. Example of the relationship between the Proteus and laboratory measurements for a source to sea study in an agricultural catchment.
Fluorescence spectroscopy is a selective and sensitive optical technique enabling in-situ, real-time measurement of dissolved organic matter. Molecules absorb light of a specific wavelength and orbiting electrons are excited to a higher energy state .The electrons then emit light of a specific wavelength to return to the base state.
The dissolved organic matter pool can be mapped in optical space based on its fluorescent properties (see Fig. 2). The TLF peak (red) represents a mixture of free amino acids, peptides and proteins but importantly also those bound into the cells of microbes. Numerous published studies have correlated TLF with faecal coliform counts and our site specific or generic calibrations are able to provide users with highly accurate and repeatable coliform measurements (Fig. 3).