Chemical Oxygen Demand Monitoring in Water Quality Systems

Chemical oxygen demand (COD) quantifies the amount of oxygen required to oxidise organic compounds in water and serves as a principal indicator of industrial and municipal pollution. Traditional COD assays rely on strong chemical oxidants and lengthy digestion steps, which generate hazardous waste and limit temporal resolution. Recent advances seek reagent-free, rapid alternatives by harnessing optical methods, electrochemical sensors and chemometric modelling. Ultraviolet-visible (UV-Vis) spectroscopy has emerged as a versatile platform for in situ and remote monitoring, often combined with machine-learning algorithms to deconvolute complex absorption spectra and compensate for interferences such as turbidity. Integration of miniaturised spectrometers into wireless sensor networks and unmanned platforms is enabling continuous, distributed surveillance of rivers, treatment works and distribution systems. Such developments align with global water-quality directives and Sustainable Development Goals, offering high-throughput, low-cost solutions for early warning, process control and ecosystem protection.

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Chemical Oxygen Demand Monitoring in Water Quality Systems publication trend

The graph below shows the total number of articles in chemical oxygen demand monitoring in water quality systems across all publications each year (not limited to Nature Index journals).

Technical terms

Chemical oxygen demand (COD): the mass of dissolved oxygen needed to fully oxidise organic matter in a water sample under specified conditions.

Ultraviolet-visible (UV-Vis) spectroscopy: analytical technique measuring light absorption by molecules in the 200–800 nm spectral range to infer chemical concentrations.

Convolutional neural network (CNN): a deep-learning architecture using convolutional layers to extract hierarchical features from spectral data for predictive modelling.

Partial least squares regression (PLSR): a multivariate statistical method that reduces spectral data dimensionality while correlating latent variables with target analytes.

Reflective detection system: an optical configuration where light reflected off a sample’s surface is measured to determine analyte concentrations without direct transmission.

References

1. Advances on Water Quality Detection by UV-Vis Spectroscopy. Applied Sciences (2020).
2. Water chemical oxygen demand prediction model based on the CNN and ultraviolet-visible spectroscopy. Frontiers in Environmental Science (2022).
3. Research on COD measurement method based on UV-Vis absorption spectra of transmissive and reflective detection systems. Frontiers in Environmental Science (2023).
4. Deep learning–based turbidity compensation for ultraviolet-visible spectrum correction in monitoring water parameters. Frontiers in Environmental Science (2022).
5. Distributed Water Pollution Source Localization with Mobile UV-Visible Spectrometer Probes in Wireless Sensor Networks. Sensors (2018).