Hydrogen Sulfide Monitoring in Wastewater Applications

CLEVELAND - June 8, 2020 - PRLog -- Hydrogen sulfide is gas commonly found in wastewater applications produced during the decomposition of organic matter. It is toxic, combustible and can be very corrosive. Monitoring it using a data logger requires an understanding of why the data is being collected and how it is being used to make the right choice in picking the appropriate measurement system.

What Is Hydrogen Sulfide?

Hydrogen Sulfide (H2S) is a colorless gas that is often described as having the odor of rotten eggs when present in low concentrations. It is flammable and releases sulfur dioxide (SO2) when burned. It can be toxic at concentrations above approximately 300 ppm. It is also very corrosive to metals, elastomers, and plastics, even to materials like concrete.

Where Does Hydrogen Sulfide Come From?

Hydrogen sulfide can be found in natural sources as unstabilized crude oil, petroleum, and natural gas and can be released when these materials are burned or vaporized. It is also present in volcanic gases, hot springs, and some well water. Hydrogen sulfide can also be found in industrial settings such as oil and gas wells, refineries, natural gas processing plants, steel mills, leather tanning facilities, sewage and wastewater pipes and treatment plants, and other types of chemical processing plants.

How Do You Monitor Hydrogen Sulfide?

There are a variety of methods to detect the presence of hydrogen sulfide. The simplest is the sense of smell. Amazingly, it is possible to smell H2S at levels of <1-10 ppm, however, you would not want to be anyplace where the level was >20 ppm for any period of time. There are several methods for chemical detection of H2S including lead acetate coated test strips, colorimetric tubes, and the Tutwiler method which utilizes chemical titration. One of the most accurate methods is gas chromatography but this requires a relatively large and expensive piece of equipment and may not be practical for use in the field.

Finally, there are electronic monitors that utilize small electrochemical sensors to detect H2S. These sensors use a specially treated sensing electrode along with an electrolyte; the incoming gas undergoes a chemical reaction at the sensing electrode that generates an electrical signal. One important consideration when using these sensors is that they have a finite operating time when used in the presence of hydrogen sulfide. Since they depend on an electrochemical reaction, there is an electrolyte that is converted as part of the reaction.

For further information on hydrogen sulfide monitoring, or to find the ideal solution for your application-specific needs, contact a CAS Data Logger Application Specialist at (800) 956-4437 or visit us at https://www.dataloggerinc.com/