New Water Contamination Detector gives Real-Time Protection

A contamination event at a UK water pumping station was successfully detected by the Chelsea Technologies (UK) FASTtracka II system. The event was automatically detected using the FASTtracka II, Fast Repetition Rate (FRR) chlorophyll a fluorometer combined with a novel Red, Amber, Green (RAG) algorithm, which has been developed to provide continuous, real-time protection for water supplies at the pre-treatment stage.

A discharge of Triclosan at a concentration of 22.6 µg l-1 was detected by one of a number of FASTtracka systems within an ongoing evaluation programme, involving UK sites operated by Veolia Water, United Utilities and Scottish Water, plus one site within the US. All FASTtracka II sensors within this trial are installed at the water intake of pumping stations, with natural flora providing the target material for FRR measurements. The RAG algorithm provides a clear display of the water condition and alarms when a contamination event is detected. Since each FRR sequence requires only 2.7 ms the system can provide very high temporal resolution (currently set at one acquisition per minute), whilst allowing for use of a very low maintenance, flow-through arrangement. Using data from the evaluation programme, the RAG algorithm now has been developed to the point where it provides extremely effective rejection of false positives, whilst maintaining high sensitivity to contamination events.

Dr Kevin Oxborough (CTG Ltd) presented results from the evaluation programme to a special interest group from UK water companies, at a meeting hosted by Veolia Water (Hatfield). The presentation included results from independent laboratory tests, which showed that the combination of FASTtracka II sensor and RAG algorithm is effective in the detection of a wide range of toxicants. Other features of the system discussed included the self-cleaning design of the sample chamber, the ability to function at high turbidity levels, the extremely high dynamic range and the real-time measurement of chlorophyll a concentration. The potential for using FRR technology for algal bloom detection was also discussed.