UV Spectroscopy A Breakthrough in Real-Time Water Quality Monitoring

Water quality is a critical global concern, influencing everything from ecosystem health to human well-being. Traditional water analysis methods, however, often fall short in providing real-time, comprehensive data.

As global concerns surrounding water quality intensify, safeguarding this indispensable resource becomes increasingly imperative. The impact of water quality affects many aspects of our lives, including our food systems, environment, and personal health. Factors such as the increasing population, intensified farming practices and industrial waste have all taken a toll on the purity of our water sources [2]. To tackle these challenges, Hamamatsu Photonics has developed an advanced UV spectrometer, offering innovative solutions for water quality management, particularly key in monitoring the environment and our drinking water. When human activities cause bodies of water to become rich in nutrients, it leads to a reduction in oxygen levels, resulting in the death of aquatic life. Monitoring wastewater quality helps detect pollution events and ensures compliance at treatment facilities[7]. For instance, hospitals and pharmaceutical plants generate concentrated antibiotic wastewater that requires treatment and analysis before release into the environment[1,14].

Water Quality and Concentional Methods for Water Analysis

Water utilities are committed to meeting the drinking-water standards set by the World Health Organization. To ensure safe and reliable drinking water, they employ rigorous water quality monitoring and treatment systems that detect and prevent potential hazards that could render drinking water unsafe [3]. Water quality monitoring usually requires sampling and shipping the samples to a laboratory. This only partially explains water quality over time and may not capture short-term fluctuations.

Delayed feedback from the laboratory also makes it difficult to respond quickly to water incidents [4]. Water quality is assessed by using chemical, biological, and physical methods. Chemical methods such as titration and electrochemical analysis determine pollutant concentrations in a lab. However, these methods require expensive equipment and many reagents and can cause secondary pollution. Biological methods involve enrichment analysis and biosensor technology but suffer from lower accuracy and sensitivity compared to other methods. The results from the chemical and biological methods are also generally not provided in real time [6].

Physical methods consist of spectral remote sensing technology in the UV and visible wavelengths. The principle of UV-Vis spectrophotometry relies on the correlation between the absorption of specific light wavelengths by a substance and its concentration [8]. Thanks to software particle compensation, spectrophotometry generally does not require sample filtrations; it is reagent-free and allows fast measurements of water quality in real time. This method has been increasingly utilized in the realm of rapid water quality assessment in recent years [6]. Among the parameters that can be measured using UV-Vis spectrophotometers are commonly color, nitrate, Depleted Oxygen Content (DOC), Total Oxygen Content (TOC), and the spectral absorption coefficient SAC254. Recently, additional parameters have been included in water quality monitoring using online UV-Vis spectrophotometers [8], such as measurements of dissolved organic matter [9], chemical oxygen demand (COD) in water bodies [10], and disinfectant in drinking water [11].

Single-Wavelength and Multiwavelength Detectors

There are two types of spectral sensors used in water analysis: single wavelength (SW) sensors and spectrophotometers. Online SW UV-Vis instruments determine concentrations of a specific water parameter measuring the absorbance of a selected single wavelength [12]. UV-Vis spectrophotometers measure the absorbance in a certain wavelength range and produce spectral fingerprints used to determine water quality concentrations of several parameters[13]. SW sensors may not compensate for particle effects accurately, while spectrophotometers provide better particle compensation and can be calibrated with higher accuracy, ideal for precise applications, such as real-time water and treatment process monitoring [13].

Hamamatsu’s innovative UV-VIS spectrometer is designed to meet the demands of modern water quality monitoring. This cutting-edge solution seamlessly blends advanced technology and practicality, ensuring accurate and efficient real-time analysis. The C16767MA mini-spectrometer head model [15] presents the most compact yet powerful solutions for situations requiring portability and efficiency. Ideal for direct installation into water pipelines or complex monitoring configurations, its streamlined design encapsulates advanced functionality within a diminutive form factor.

The UV-VIS spectrometer exhibits exceptional sensitivity across a wavelength range spanning from 190 to 400 nm. This allows for precise measurement of critical water quality parameters, thereby enabling comprehensive insight into water composition. The distinctive compact form of our spectral sensor facilitates seamless integration into miniature and handheld instruments. These sensors can be effortlessly incorporated directly within water pipelines, underscoring their adaptability and ease of deployment.

Hamamatsu's UV spectrometer boasts an unparalleled dynamic range, ensuring dependable measurements amidst dynamic environmental conditions. This makes them ideal for dependable operation in outdoor settings, where fluctuations are inherent. Our new UV spectrometers achieve a high Signal-to-Noise Ratio (SNR) enabling the early detection of even the most subtle fluctuations in water quality, facilitating preemptive alarms and swift corrective actions. By curbing crosstalk among different wavelength readings, the accuracy of Hamamatsu's UV spectrometer is significantly enhanced. This design detail ensures the production of reliable and consistent measurements, critical for meaningful analysis.

Navigating the Future of Water Quality With UV Technology

Hamamatsu's cutting-edge UV spectrometer offers a vital solution to the escalating global water quality challenges. From addressing nutrient imbalances jeopardizing aquatic ecosystems and food supplies to ensuring stringent drinking water standards, these spectrometers cater to diverse concerns. The future of water quality management lies in innovation. By continuing to refine and expand these technologies, we can better protect our most valuable natural resources. Water is life, and through continuous advancements in real-time monitoring, we are safeguarding it for future generations. With tools like Hamamatsu’s compact UV spectrometers, the path toward a more sustainable and healthier planet is clearer than ever. (heh)

References

[1] F. S. Chapin III, P. A. Matson, and P. M. Vitousek, Principles of Terrestrial Ecosystem Ecology, 2nd ed., Springer, 2011.

[2] H.I. Chaminé, "Water resources meet sustainability: new trends in environmental hydrogeology and groundwater engineering," Environ Earth Sci, vol. 73, pp. 2513-2520, 2015. doi: 10.1007/s12665-014-3986-y.

[3] Z. Shi, C.W.K. Chow, R. Fabris, J. Liu, and B. Jin, "Applications of Online UV-Vis Spectrophotometer for Drinking Water Quality Monitoring and Process Control: A Review," Sensors, vol. 22, no. 8, article 2987, 2022. doi: 10.3390/s22082987.

[4] M.H. Banna, S. Imran, A. Francisque, H. Najjaran, R. Sadiq, M. Rodriguez, and M. Hoorfar, "Online Drinking Water Quality Monitoring: Review on Available and Emerging Technologies," Critical Reviews in Environmental Science and Technology, vol. 44, no. 12, pp. 1370-1421, 2014. doi: 10.1080/10643389.2013.781936.

[5] A.-E. Briciu, A. Graur, and D. I. Oprea, “Water Quality Index of Suceava River in Suceava City Metropolitan Area,” Water, vol. 12, no. 8, p. 2111, Jul. 2020, doi: 10.3390/w12082111.

[6] G.V. Pashkova and A.G. Revenko, "A Review of Application of Total Reflection X-ray Fluorescence Spectrometry to Water Analysis," Applied Spectroscopy Reviews, vol. 50, no. 6, pp. 443-472, 2015. doi: 10.1080/05704928.2015.1010205.

[7] E.M. Carstea, J. Bridgeman, A. Baker, and D.M. Reynolds, "Fluorescence spectroscopy for wastewater monitoring: A review," Water Research, vol. 95, pp. 205-219, 2016. doi: 10.1016/j.watres.2016.03.021.

[8] Y. Guo, C. Liu, R. Ye, and Q. Duan, "Advances on Water Quality Detection by UV-Vis Spectroscopy," Appl. Sci., vol. 10, p. 6874, 2020. doi: 10.3390/app10196874.

[9] P. Li and J. Hur, "Utilization of UV-Vis spectroscopy and related data analyses for dissolved organic matter (DOM) studies: A review," Crit. Rev. Environ. Sci. Technol., vol. 47, pp. 131-154, 2017. doi: 10.1080/10643389.2016.1224573.

[10] F. Liu, P. Zheng, B. Huang, X. Zhao, L. Jiao, and D. Dong, "A review on optical measurement method of chemical oxygen demand in water bodies," in Proceedings of the International Conference on Computer and Computing Technologies in Agriculture, Beijing, China, 27-30 September 2015, pp. 619-636.

[11] S. Hossain, C. W. Chow, G. A. Hewa, D. Cook, and M. Harris, "Spectrophotometric online detection of drinking water disinfectant: A machine learning approach," Sensors, vol. 20, p. 6671, 2020.

[12] J. van den Broeke, G. Langergraber, and A. Weingartner, "On-line and in-situ UV/vis spectroscopy for multiparameter measurements: a brief review," Spectroscopy Europe, vol. 18, no. 4, pp. 15-18, 2006.

[13] Z. Shi, C.W. Chow, R. Fabris, J. Liu, and B. Jin, "Alternative particle compensation techniques for online water quality monitoring using UV–Vis spectrophotometer," Chemometrics and Intelligent Laboratory Systems, vol. 204, p. 104074, 2020.

[14] Li F., Wang X., Yang M., Zhu M., Chen W., Li Q., Sun D., Bi X., Maletskyi Z., Ratnaweera H. "Detection Limits of Antibiotics in Wastewater by Real-Time UV–VIS Spectrometry at Different Optical Path Length." Processes, vol. 10, no. 12, p. 2614, 2022. [Online]. Available: https://doi.org/10.3390/pr10122614

[15] “Fingertip-sized, ultra-compact spectrometer head supporting high UV sensitivity” [Online].

* Gaetano Panagia is Technical Marketing Engineer at Hamamatsu.

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