Fluorescence analysis of centralized water supply systems: Indications for rapid cross-connection detection and water quality safety guarantee

Area of Science:

• Environmental Science
• Analytical Chemistry
• Water Quality Monitoring

Background:

• Sustainable water reuse requires reliable methods to differentiate reclaimed water from drinking water.
• Cross-connections between water systems pose risks to public health and water integrity.
• Conventional water quality parameters may lack the sensitivity for early detection of contamination.

Purpose of the Study:

• To evaluate the effectiveness of fluorescence excitation-emission matrix (EEM) for rapid detection of cross-connections between reclaimed and drinking water systems.
• To identify key fluorescent components in reclaimed water that enable detection.
• To assess the sensitivity of EEM for detecting low concentrations of reclaimed water in drinking water.

Main Methods:

• Utilized fluorescence excitation-emission matrix (EEM) spectroscopy on water samples from three sites in China.
• Applied parallel factor analysis (PARAFAC) to identify fluorescent components.
• Investigated total fluorescence intensities and peak characteristics under various mixing scenarios.

Main Results:

• Overall fluorescence intensity was 6-31 times higher in reclaimed water compared to drinking water.
• Humic acid and tryptophan were identified as major fluorescent contributors in both secondary and tertiary effluents.
• EEM signals were distinguishable even with as little as 20% reclaimed water presence.
• The method demonstrated higher sensitivity than conventional water quality parameters.

Conclusions:

• EEM is a highly sensitive and rapid technique for detecting cross-connections in water reuse systems.
• Fluorescent components like humic acid and tryptophan serve as reliable indicators of reclaimed water presence.
• The findings support the development of portable EEM devices for real-time water quality monitoring and risk prevention at end-user sites.