Five-star restaurant effluent: UV on the menu

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  • Published: Jan 5, 2012
  • Author: David Bradley
  • Channels: UV/Vis Spectroscopy
thumbnail image: Five-star restaurant effluent: UV on the menu

Waste not, want not

A water-quality system based on multiple sensors, UV-Vis spectroscopy, and turbidity measurements can be used to monitor waste water from restaurants and other sites. Writing in the journal Water Research, the developing team offers a case study as proof of principle.

Xusong Qin, Furong Gao and Guohua Chen of the Department of Chemical and Biomolecular Engineering, at The Hong Kong University of Science and Technology, in Kowloon, explain how monitoring waste water quality is of increasing importance not least because of growing environmental concerns but also because online monitoring can lead to better treatment plant control and even reduce energy costs by up to 40 per cent. Unfortunately, current monitoring techniques are stymied by sampling and sample storage problems as well as the complexity of the sample matrix. Moreover, conventional analytical techniques available for waste water monitoring are not amenable to real-time monitoring and so do not offer options for online treatment-process control. As such, the automation of waste water treatment systems is, the team says, still not as developed as other process industries.

They point out that UV-Vis spectroscopy has great potential in the field of online waste water monitoring and has been investigated by several times in recent year. Unfortunately, the majority of the effort in this area has simply focused on visual observation and direct comparison of spectra, which is not a tenable option for automated monitoring. Additionally, the research so far has used test samples that are not necessarily representative of the kind of waste water effluent released by restaurants, for example. Such waste water is usually rich in oil and grease, suspended solids and colloids. Such samples are not best suited to optical techniques, the team points out. The researchers suggest that the most apt solution to the problem of such sample complexity is increased sensor complexity through the use of fusion technology. In such a set-up data from multiple sensors are fed into a mathematical model tuned to extract the requisite information quickly.

Multisense

"Multi-sensor data fusion, first appeared in the literature as mathematical models for data manipulation in the 1960s," the team says. "It refers to the acquisition, processing and synergistic combination of information gathered by various knowledge sources and sensors to provide a better understanding of a phenomenon." In the last few decades the concept has been applied in military command and control, robotics, image processing, air traffic control, medical diagnostics, pattern recognition and environmental monitoring, they add. Unfortunately, there is no one-size-fits-all model for any analytical process.

The team has now developed a waste water quality monitoring system that incorporates a UV/Vis spectrometer and a turbidity meter to monitor COD (chemical oxygen demand), TSS (total suspended solids) and O&G (oil and grease) concentrations of the waste water effluent from a Chinese restaurant on the team's campus and an electrocoagulation-electroflotation (EC-EF) waste water treatment pilot plant. The prediction models for these water quality parameters were constructed by a Boosting-IPW-PLS (iterative predictor weighting, partial least squares) method developed by the team as part of the study. "Experimental results showed that the predicted values fit the analytical values well with high correlation coefficients and small root mean square error values, "the team concludes, revealing the effectiveness of the proposed system.


The views represented in this article are solely those of the author and do not necessarily represent those of John Wiley and Sons, Ltd.

A water-quality system based on multiple sensors, UV-Vis spectroscopy, and turbidity measurements can be used to monitor waste water from restaurants and other sites. Writing in the journal Water Research, the developing team offers a case study as proof of principle.

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