Ambient hydrogen sulphide levels at a wastewater treatment plant.

This paper describes a novel technique of measuring ambient hydrogen sulphide (H2S) concentrations simultaneously at several locations around a wastewater treatment plant. A commercially purchased H2S monitor is modified to operate in a 'static mode' to enable degree of darkening on pieces of lead acetate tapes to be correlated againts the exposure duration and the ambient H2S concentration of sewage air. The technique can yield mapped contours of time-average H2S concentrations as low as 0.2 ppm. The methodology is exemplified for a wastewater treatment plant in Ipswich, Queensland. Isopleths of H2S concentration obtained at the wastewater site for two different meteorological conditions reveal that high levels of H2S are detected around the plant's inlet structure and primary clarifiers.