By relying on intricate laboratory measurement methods and analysis procedures, as standard practice to date, system operators have received corresponding information based on a specific point in the past. Necessary responses are therefore delayed and may prove to be costly. Precise chlorite values are now available on request online in real time. This development ensures maximum safety and reliability while permitting immediate intervention as required. For this purpose, ProMinent has developed the world's first measuring station that uses the amperometric principle for determining chlorite. Experts from the "Deutsche Vereinigung des Gas- und Wasserfaches" DVGW (German Association of Gas and Water Trades) as well as from the "Zweckverbandes Landeswasserversorgung (LW) Baden-Württemberg" (Special Purpose Water Supply Utilities, Baden-Württemberg) recommend this method. The measuring station is convenient and easy to install, calibrate and service.
 The strongly oxidising agent anionic chlorite is produced as a by-product at various stages in the drinking water treatment process involving chlorine dioxide. The ClO2- level fluctuates depending on the rate of chlorine dioxide metering and the levels of organic and inorganic substances in the water, rendering continuous monitoring necessary throughout the production process. The ProMinent online measuring station with patent pending effectively performs this water monitoring task.
Technicians connect the unit, preassembled on a panel, to the output of the chlorine dioxide metering unit directly downstream of the mixer. The heart of the unit is the chlorite sensor CLT1 that is installed in a bypass fitting. The measured signal is evaluated in the measuring instrument D1CA. This instrument can transfer a 4-20 mA output signal to a higher-level control room. The online measuring station can be integrated in control circuits. Convenient calibration ensures reliably accurate values. Cross-sensitivity to chlorine dioxide, chlorine and chlorate is negligibly low.
Compared to conventional analysis methods, the technicians in the waterworks benefit primarily from increased transparency in the process and rapid fault or malfunction indication at low costs and time requirements. They are additionally assured of receiving up-to-date information to effectively prevent damage. Long service life of the sensor and minimum installation and servicing requirements reduce costs even further.
Specialists at the DVGW Technology Center for Water in Dresden (TZW) and the Baden-Württemberg Water Supply Utility (Langenau) have systematically and objectively tested the measuring station and measuring principle and compared them, using differentiated criteria, with conventional test and analysis methods.
The result:
The online measuring method comes out on top of the standard photometric methods in all assessments. Its measuring principle is just as accurate as the ion chromatographic reference method – but only much faster and more cost-effective. The DVGW therefore recommends monitoring the sensitive parameter chlorite with the ProMinent online process monitoring system. |