ATi's Dissolved Hydrogen Sulphide Monitor Achieves Accurate Hydrogen Sulphide Measurements In Water

Middlewich, UK - Analytical Technology Inc. (ATi) announced that its A15/81 dissolved hydrogen sulphide monitor is the first system to achieve precise and direct measurements of hydrogen sulphide levels in water. The analyser provides continuous, accurate and sensitive measurements of true dissolved sulphide levels whilst requiring very little maintenance due to non-contact gas phase measurement. The A15/81 monitor is of particular interest to the metals industry, where the measurement of sulphides is an essential part of the wastewater treatment process.

Sulphides can be present in water for a number of reasons. In the metals industry, they can be a by-product of another material, produced by biological activity or used as a dosing material to remove metals from water by forming an insoluble substance. The use of sulphides in water is strictly regulated by water companies and the Environment Agency through the granting of consent to discharge. This permit dictates that companies must prove that the effluents discharged to public sewers do not contain excessive amounts of sulphides. As a result, organisations working in the metals industry require an analyser capable of measuring sulphides in water while providing dependable and accurate results in order to comply with these guidelines.

ATi's A15/81 monitor removes the need to analyse samples in a laboratory by enabling sampling at any point in the wastewater process. The instrument uses a polarographic H₂S gas sensor that never comes into contact with the sample, thus eliminating the fouling that is typically associated with H₂S measurements. Using a gas stripping technique for monitoring hydrogen sulphide in solution, the instrument provides extreme sensitivity on line and is capable of indicating the residual sulphide in a range up to 20 parts per million. Furthermore, the design of the analyser ensures that monthly zeroing and calibration intervals are more than adequate.

The A15/81 consists of two parts: a chemistry module where the sample is conditioned and an electronic display unit that shows the sulphide concentration. The electronics have 4-20mA outputs and alarm relays as standard. In operation, a small amount of sample is pumped into the analyser and mixed with acid, causing chemical reactions that lead to the production of H₂S. The sample then flows to an air-stripping chamber, where measurement of gas phase H₂S is carried out and the monitor displays an equivalent sulphide concentration in mg/l.

In addition to aiding regulatory compliance by providing accurate and direct measurement of sulphides in water, the A15/81 monitor can be used to control the level of sulphides in water, and to test wastewater for biological activity.

SOURCE: Analytical Technology Inc.