Hydrogen Sulfide Testing at a Wastewater Treatment Facility

Based on three odor complaints received by Maricopa County from residents close to a wastewater treatment facility in Tolleson, Arizona, the Operations Manager, David Tyler, along with an Arizona Instrument team, tested the air at the closest occupied location, which is an elementary school on the corner of 91st Avenue.

Odor Analysis

The odor was very pungent with smell reminescent of burnt materials. Since the odor of hydrogen sulfide is a unique rotten egg smell, the team did not believe that the smell was coming from the wastewater facility. The team also learned that there is a dairy and a meat packing facility within two miles of the school, and the unpleasant odors may be coming from these facilities.

The team sampled the air in the parking lot for 30min utilizing the Jerome® J605 Hydrogen Sulfide Analyzer equipped with an ammonia scrubbing filter. The device was set to ‘survey mode’ and the site was labeled as ‘school.’ During the analysis, the J605 did not detect any hydrogen sulfide and was in the range ‘0.’ The team informed the elementary school management that they did not determine any harmful gases.

Besides conducting the test at the school, the wastewater facility operations manager performed a perimeter test by setting the site to ‘fence.’ He walked along the surrounding fence and measured emissions in survey mode. The J605 was in the range ‘0’ for the vast majority of the fence line, except the region where the wastewater entered the facility. At this area, the reading was as high as 110ppb. Although ammonia and chlorine bleach odors were there in a few processing areas, no signal was generated.

Subsequent to the perimeter walk, the team analyzed other areas in the facility by walking from end to end through the middle of the compound, starting in the north and heading to the south, and again from the east and heading west. The J605 readings were in 0.00ppb during the north/south testing.

When the team walked from east to west, it traversed the sludge drying beds where air drying of solid waste is performed prior to shipping or sale. The material beds were roughly 30% filled, with a smell of plant fertilizer. The J605 did not detect any hydrogen sulfide in this area. However, the device did respond again when the team passed through the region where raw sewage entered the facility.

The team finally tested the air scrubbers at the exhaust of the sealed sewage processing station using the J605. They are two roughly 6-foot-dia cylindrical scrubbers rising roughly 20 feet off of the ground, consisting of activated carbon.

According to Tyler, this was the first time the scrubbers tested for ensuring their operational efficiency. The readings at the scrubber top where the air enters the atmosphere were 3ppm hydrogen sulfide for scrubber 1 and 8ppm for scrubber 2. The J605 measured 1ppm hydrogen sulfide for gases coming into the scrubbers.

During general conversation, Tyler mentioned that the facility has the capability of analyzing in-sludge, but does not typically perform this analysis, as the sludge is air dried for weeks before distribution off-site. Nevertheless, many larger facilities do not have the capability of air drying their sludge for weeks and using a rapid loss-on-drying instrument would be advantageous for monitoring mechanical drying processes. For the question of mercury analysis in water, Tyler answered that the facility performs mercury analysis, but off-site by sending water samples to an independent lab for metal analysis.

From an analysis perspective, the team was able to begin understanding the wastewater treatment process and the use of Arizona Instrument devices to maintain the level of hydrogen sulfide from the Tolleson wastewater facility below prescribed levels.


In its first visit, the Arizona Instrument team was able to point out the necessity of monitoring the cleaning scrubbers in order to ensure their proper operation. Also pointed out was the advantage of using a rapid loss-on-drying instrument for solid content determination at wastewater treatment facilities that are using mechanical drying processes and shipping material immediately after the drying process, in order to ensure the efficient operation of the dryers.

Performing mercury analysis would be advantageous, but difficult as a stand-alone process as the facility is equally interested in determining other metal contaminant levels.

Arizona Instrument

This information has been sourced, reviewed and adapted from materials provided by AMETEK Brookfield Arizona

For more information on this source, please visit AMETEK Brookfield Arizona


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