Water & Wastewater Treatment Magazine
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22 | JULY 2016 | WWT | www.wwtonline.co.uk In the know Research Notes: water quality at the University of Birmingham have developed a novel optical instrument, based on uorescence spectroscopy, to indicate water quality and suitability for consumption almost instantly. All water uoresces, although the insensitivity of the human eye to the appropriate wavelengths renders uorescence invisible to us. Research has demonstrated that water uorescence is particularly good at identifying faecal contamination. The uorescence emitted from humic and fulvic substances, uorescent pollutants such as whitening agents, and microbially-derived intrinsic uorescence from both cellular material and exudates can all be detected. The advantages of uorescence include a rapid analysis time, no sample pre-treatment necessary, and a sample volume of only a few microlitres. We have developed a prototype dual-LED instrument, 'Duo Fluor'. This can detect uorescence at wavelengths that can be used as surrogates for both microbial and organic carbon presence. We have benchmarked prototype performance against research grade instruments and recorded excellent performance. Our initial work examined the feasibility of using the Duo Fluor as a proxy for organic matter. The instrument detected fulvic acid at 0.25 mg/l, and could diˆ erentiate between deionized water and tap water. Attempting to observe similar diˆ erences using standard TOC analysis was less successful, meaning that the Duo Fluor could detect lower levels of pollution than standard TOC analysis. The response of the Duo Fluor to deionized water, as a clean control, and local pond waters spiked with L-Tryptophan was subsequently the management of water and wastewater systems in both developed and developing countries. It oˆ ers multiple potential uses within the global water industry for the rapid, cost-eˆ ective and robust indication of: • organics and microbial matter across a wide range of water qualities (from sewage to drinking water) • process effi ciency at treatment works • identifi cation of potential ingress into service reservoirs and distribution systems • disinfection byproduct formation potential • effl uent quality at wastewater treatment works • river water quality at abstraction points and wastewater treatment works' discharge points • identifi cation of misconnected sewer discharges. The equipment is inexpensive and oˆ -the-shelf; furthermore, it allows both expert interpretation of results and simplifi ed pictorial interpretation for use by non-experts. This provides the additional benefi t of community empowerment through involving water users themselves in the application of the technology. With expert advice from Oxfam and funding from the Engineering and Physical Sciences Research Council and the Diageo Foundation, we are now working to refi ne the instrument design to suit the needs of water utilities in developed nations, and also develop a version that is ideally suited to disaster relief and areas of poor sanitation. By facilitating the timely detection of unsafe sources of drinking water, the Duo Fluor should oˆ er a reliable technique to help minimize the likelihood of future widespread outbreaks of cholera and other water- related diseases in areas of poor sanitation. assessed. Incremental dosing of Tryptophan into both types of water yielded a steady uorescence signal response demonstrating the capability to detect a surrogate for microbial presence. (Figure 1) Duo Fluor performance has also been assessed when continuously measuring the Peak T uorescence (a surrogate for microbial presence) and Peak C uorescence (a surrogate for humic and fulvic acids) of pond water spiked with quinine sulphate (QS). It was used to analyse water quality continuously over three distinct phases: 15 minutes of water owing continuously with no addition of QS; 15 minutes of water spiked with 0.4 mg/L QS, and fi nally 15 minutes of water spiked with 0.8 mg/L QS. The results are shown in Figure 2 and demonstrate an appropriate and anticipated response in both Peak C and Peak. Unlike most commercially- available instruments, uorescence responses can be enhanced by adjusting gain settings. This means it can be set up to provide an accurate comparison among samples as well as allowing the most appropriate sensitivity ranges to be identifi ed for the quality of water being tested. The Duo Fluor represents a hugely signifi cant advance for Figure 1. Peak T fl uorescence output of samples dosed with L-Tryptophan Figure 2. Peak C and Peak T response to quinine sulphate dosing in river water