Monitoring the influence of wastewater effluent on a small drinking water system using EEM fluorescence spectroscopy coupled with a PARAFAC and PCA statistical approach

Spectral fusion-based machine learning classifiers for discriminating membrane breakage in multiple scenarios

Membrane breakage can lead to filtration failure, which allows harmful substances to enter the effluent, posing potential hazards to human health and the environment. This study is an innovative combination of fluorescence and ultraviolet-visible (UV-Vis) spectroscopy to identify membrane breakage. It aims to unravel more comprehensive information, improve detection sensitivity and selectivity, and enable real-time monitoring capabilities. Fluorescence and UV-Vis data are extracted through variance partitioning analysis (VPA) and integrated through a decision tree algorithm to form a superior system with enhanced discrimination capabilities. VPA improves discrimination efficiency by extracting key information from spectral data and eliminating redundancy. The decision tree algorithm, on the other hand, can process large amounts of data simultaneously. In addition, the method has a wide range of applications and can be used in various scenarios accurately. The scenarios include domestic sewage, micropollutant water, aquaculture wastewater, and secondary treated sewage. The experimental results validate the application of machine learning classifiers in membrane breakage detection with an accuracy rate of 96.8 % to 97.4 %.

Validation of conventional and synchronous fluorescence emission of potable water

Water from filter plants and bottled water is generally safe to drink but regular quality monitoring of these facilities requires development of quick analytical technique to ensure public safety and health. This study presented the variation of two components in spectra of conventional fluorescence spectroscopy (CFS) and four components in synchronous fluorescence spectroscopy (SFS) to assess the quality of 25 water samples from different sources. Poor quality water either due to organic or inorganic contaminants presented high intensity fluorescence emission in the blue green region and low intensity water Raman peak unlike an intense water Raman peak originated from pure water when excited at 365 nm. Emission intensity in the blue green region and water Raman peak can be used as a marker for quick screening of water quality. Although few discrepancies were observed in CF spectra of samples with intense Raman peak but were found to be positive for bacterial contamination, thus questioning the sensitivity of CFS that needs to be addressed. Whereas, SFS presented highly selective and detailed picture of water contaminants emitting aromatic amino acid, fulvic and humic like fluorescence. It is suggested that the specificity of CFS can be enhanced by coupling it with SFS or use of multiple excitation wavelengths to target different fluorophores for water quality analysis.

A review on fluorescence spectroscopic analysis of water and wastewater

In recent years, the application of fluorescence spectroscopy has been widely recognized in water environment studies. The sensitiveness, simplicity, and efficiency of fluorescence spectroscopy are proved to be a promising tool for effective monitoring of water and wastewater. The fluorescence excitation-emission matrix (EEMs) and synchronous fluorescence spectra have been widely used analysis techniques of fluorescence measurement. The presence of organic matter in water and wastewater defines the degree and type of pollution in water. The application of fluorescence spectroscopy to characterize dissolved organic matter (DOM) has made the water quality assessment simple and easy. With the recent advances in this technology, components of DOM are identified by employing parallel factor analysis (PARAFAC), a mathematical trilinear data modeling with EEMs. The majority of wastewater studies indicated that the fluorescence peak of EX/EM at 275 nm/340 nm is referred to tryptophan region (Peak T1). However, some researchers identified another fluorescence peak in the region of EX/EM at 225-237 nm/340-381 nm, which described the tryptophan region and labeled it as Peak T2. Generally, peak T is a protein-like component in the water sample, where T1 and T2 signals were derived from the <0.20μm fraction of pollution. Therefore, a more advanced approach, such as an online fluorescence spectrofluorometer, can be used for the online monitoring of water. The results of various waters studied by fluorescence spectroscopy indicate that changes in peak T intensity could be used for real-time wastewater quality assessment and process control of wastewater treatment works. Finally, due to its effective use in water quality assessment, the fluorescence technique is proved to be a surrogate online monitoring tool and early warning equipment.