Monitoring Goes Miniature

The i::scan spectrophotometer brings drinking water monitoring down to a small scale and a lower cost. The compact unit can measure multiple parameters.
Monitoring Goes Miniature
The i::scan probe can be combined in a nano::station with pH, chlorine and conductivity sensors in a compact footprint.

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Monitoring water quality costs money, and monitoring multiple parameters with inline devices can be beyond the budget of a smaller utility.

Addressing that and other monitoring issues, s::can offers a miniature spectrophotometer that can measure turbidity, TOC, color, UV254 and other parameters, all in one cylindrical probe that measures 12 inches long and 1 inch in diameter.

It uses an array of narrow-band LED light sources and charge-coupled device (CCD) receptors. Proprietary algorithms translate optical spectral data into accurate measurements. It can be used in water-quality control stations, smart water grids, coagulation control systems and other drinking water applications, and for various purposes in wastewater treatment and industrial processes. The probe easily communicates with SCADA and other control systems.

Michiel Lensink, business development director with s::can, talked about the i::scan technology and its applications in an interview with Water System Operator.

wso: What was the rationale for developing this technology?

Lensink: s::can was the first company to use spectrometers for online measurement, and we have sold thousands of those systems. Our original spectrometer is a complete spectrum system, and we saw many applications that didn’t need that level of sensitivity. We were looking for a very low-cost solution that would open new possibilities.

wso: What makes this technology especially useful for water utilities?

Lensink: In particular, drinking water utilities in smaller communities found it difficult to measure more than just turbidity and sometimes UV 254. To measure finished water quality, you need a TOC measurement, and the products available for doing that were expensive and quite complicated, often requiring large cabinets. i::scan makes it possible to analyze cost-effectively for TOC and a number of other parameters with one sensor.

In addition, we can combine the i::scan probe in what we call a nano::station with pH, chlorine and conductivity sensors in a very compact footprint, less than one-tenth the size of a traditional station and at a fraction of the cost.

wso: In basic terms how does this probe work?

Lensink: It uses LED light sources and two CCD measuring devices, one 180 degrees from the light source and one at 90 degrees. It measures the scattering of the light for turbidity, and it measures light absorption in the water. A number of proprietary algorithms use the measured absorption to calculate all the different parameters.

The LEDs last a very long time and consume very little energy — on the order of one watt. That means the probes can be easily powered by solar panels and used in small unmanned monitoring stations.

wso: Can this technology be used in the distribution system as well as in the treatment plant?

Lensink: Yes. To cite one example, a regional water company in the Netherlands serving about one million people plans to install about 30 of these probes to monitor the quality of water as it travels through the distribution piping. Another application is for event detection in the distribution system. The probes can be installed at remote monitoring stations and programmed to detect adverse events and send alarms.

wso: What is required to use this device in a monitoring system?

Lensink: The device is self-contained. As a light-source-based device, it requires no reagents or other consumables. It plugs into a small data acquisition terminal, which connects to the SCADA system. We offer a very simple terminal that collects the data and sends it through, and a more advanced terminal that can be used for event detection.

wso: How durable is this probe?

Lensink: The housing is made from PEEK [polyetheretherketone], an advanced polymer that withstands high temperatures and all chemicals. It has sapphire windows, which are also extremely durable.

wso: How might this technology be deployed in a treatment plant setting?

Lensink: The possibilities are quite broad. Some utilities may want to measure at certain points in the process. It is used often at the water intake to measure the quality of water coming into the system.

It can also be used to control the use of coagulants. Often, treatment plants analyze a grab sample of water and then set the coagulant feed control based only on the flow of water. But the water quality — the TOC level, for instance — varies over time. So if you can measure TOC online before coagulant dosing, you can automatically adjust the coagulant dose to the TOC value of the incoming water. That saves money because you don’t overdose coagulant, and you also ensure quality because you don’t underdose.



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