Tackling water quality challenges with compact uv spectroscopy

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 sources². 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.

Environmental monitoring

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 facilities⁷. For instance, hospitals and pharmaceutical plants generate concentrated antibiotic wastewater that requires treatment and analysis before release into the environment.^1,14

Water quality monitoring

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 unsafe³.

Conventional methods for water analysis

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 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, 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 time⁶. 

UV-Vis spectroscopy for online water monitoring

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 concentration⁸.

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 used in rapid water quality assessment in recent years⁶. 

Among the parameters that can be measured using UV-Vis spectrophotometers, are commonly colour, 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 spectrophotometers⁸, such as measurements of dissolved organic matter⁹, chemical oxygen demand (COD) in water bodies¹⁰, and disinfectant in drinking water¹¹.

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 monitoring¹³.

Compact UV spectrometers

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.

Precise measurement: Our UV-Vis spectrometer exhibits exceptional sensitivity across a wavelength range spanning from 190 to 400nm. This allows for precise measurement of critical water quality parameters, thereby enabling comprehensive insight into water composition.

Compact design: 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.

Reliability outdoors: 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.

Early detection: 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 pre-emptive alarms and swift corrective actions.

Enhanced accuracy: 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 jeopardising aquatic ecosystems and food supplies, to ensuring stringent drinking water standards, these spectrometers cater to diverse concerns. They signify Hamamatsu’s commitment to elevating water quality management and securing the purity of our vital water resources.

References

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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.
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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 

Further information

Find out more information about Hamamatsu’s advanced UV spectrometers for water quality management by visiting the company's website.