Hazardous Gases in Waste Water Treatment

Wastewater and potable water treatment facilities produce and use various toxic and explosive gases such as methane, hydrogen, sulfide, ammonia, carbon dioxide, carbon monoxide, chlorine, ozone, etc. In addition, in confined spaces, the increased concentration of toxic gases and the decreased in oxygen make these areas particularly dangerous for workers.

The sanitation process

Gas and associated risks

Several technologies can be employed to detect gases present in water treatment facilities. 

  • Electrochemical sensors are used to monitor oxygen levels in the air, or the presence of toxic gases such as CO, H2S, and Cl2.
    • Electrochemical sensors: 

Electrochemical sensors provide monitoring for a wide variety of toxic gases. An electrochemical sensor works via an aqueous electrolyte solution that provides a conductive path for ions to travel between electrodes. Target gases are either reduced or oxidized at the working electrode resulting in a current flow between the working and the counter electrode. The reference electrode provides a zero reference point from which the resulting difference in potential between the counter and working electrodes can be compared. Target gas levels can be measured in parts per million (ppm).

  • Semi-conductor sensors are used where there are high concentrations of H2S or where the ambient temperature is high.
    • Metal oxide semiconductor gas sensors utilize thin films of metal oxides placed upon a silica substrate. The substrate is heated around 200-600°C while the resistance of the metal oxide is continuously monitored. The sensor responds to changes in the atmosphere as the resistance value of the metal oxide changes when exposed to target gases.
  • Catalytic sensors are used for the detection of explosive gases.
  • Infrared sensors are used for the detection of explosive gases such as CH4 or carbon dioxide (CO2).
  • Infrared technology sensors are recommended for corrosive atmospheres or where high levels of H2S are present. Continued high concentration of H2S (above 3 ppm) will create a risk of saturation and poisoning for standard catalytic cells.

Our infrared sensor cells are not sensitive to these “poisons” (H2S, chlorinated solvents…) and last longer. Maintenance is reduced to one annual test.

Energy consumption is 2 times less than for catalytic detectors, and they are guaranteed for 5 years.

Teledyne Gas & Flame Detection offers a wide range of fixed and portable detectors

The industrial product line of Teledyne Gas & Flame Detection was designed to be used in the most extreme environments and is well-adapted for use in the water sector: use in areas with and without explosion hazard classifications, high protection index, stainless steel or polyester casing.

Our units have many functional features including RS-485 outputs, TCP/IP interfaces, programmable relays, backlit LCD displays and 24/7 data recording.

In saline, moist, or corrosive environments or where there is a high concentration of H2S, we recommend Stainless Steel (INOX) detector housings as for maximum longevity.

Teledyne Gas & Flame Detection also offers wireless solutions.

For use in confined spaces, we recommend use of a sampling enclosure.

Biological treatment facilities are usually situated far from production facilities, and staff who work at and maintain these facilities often work alone. For complete safety, operators are equipped with portable gas detectors, maintained and tested regularly.

Contact us at gasandflamedetection@teledyne.com

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