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Reliable Hamilton sensors for measurements of dissolved oxygen, pH, and conductivity

(Bonaduz, 12.08.2020) – The in-line optical dissolved oxygen sensors of Hamilton Bonaduz AG are designed for measuring the dissolved oxygen concentration in sewage treatment. “Controlling the dissolved oxygen concentration is for example important for activated sludge processes in wastewater treatment plants. The sludge in the aeriation tanks is enriched with wastewater, followed by aeriation, which increases the dissolved oxygen content and in turn fosters the bacteria activity”, knows Dr. Knut Georgy, Senior Market Segment Manager Process Analytics at Hamilton Bonaduz AG. The VisiWater DO as stainless-steel version is used in housings and pipes, whereas the plastic counterpart is used directly in tanks and ponds. The company especially developed the VisiWater DO P that convinces with a robust plastic shaft, which does not corrode even when continuously used in aggressive wastewaters. The operating principle of both sensors is identical. A built-in micro-transmitter in the sensor-head secures direct communication to the process control system via 4-20 mA or Modbus interfaces and stores calibration data as well as diagnostic information. Configuration and calibration can be carried out by means of the ArcAir app, allowing access via different mobile devices to all relevant data. The sensor provides robust signals and ensures this way long data transmission routes to the control system.

For the cultivation of the microorganisms in the activated sludge basin, a successful biological wastewater treatment is necessary that needs to be monitored with the help of pH sensors. If measured values deviate from the required ones, it might indicate e.g. a disturbance in the sewer system. The Polilyte Plus HF as example is suited for a measuring range of pH 0 up to 14. The hydrogen fluoride resistant glass electrodes show low electrical resistance, which makes them ideally suited for cold wastewaters. The long-term stable reference electrolyte Polisolve Plus contributes to the longevity and ensures reproducible measurements. The specifically developed Single Pore® liquid junction technology prevents contaminations, secures stable measurements and allows for easy cleaning.

Finally, the conductivity of the wastewater plays an important role, since it indicates the level of the contamination and allows a statement regarding the total content of dissolved salts. The more salts, acids or bases present, the higher the conductivity. More advantages of the 2-pol-sensor Conducell 2DC lies in its sturdiness, easy cleaning and the five meters long fix-cable that allows submersion. “Thanks to our sensors, measurement values beyond tolerance limits are detected immediately. Thus, appropriate corrective actions can be taken quickly”, concludes Dr. Georgy.