Air Discharge Odor Control At A Rendering Facility

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A rendering facility contacted Aulick to address odorous areas of concern based on their production process and the air being discharged from the facility.

  • Industrial Solutions
  • Odor Control



Odor control represents one of the most challenging problems facing industry today. Not only is it a nuisance, odor can also pose extreme safety hazards for plant personnel and is detrimental in its corrosion of plant equipment. All odorous compounds have different levels of toxicity while one of the major odorous compounds found in industry today is hydrogen sulfide.

Odor control is a vital part of operations for facilities determined to keep up with increasing government emissions regulations. It’s also essential for improving conditions for workers and residents of the surrounding area.

There are many odor control products currently available on the market. Through our research, however, we find that they fall short in one of two areas. Either they act merely as deodorizers by masking odors without addressing the elimination of toxic gases, or, they eliminate the odorous gases, but do so by introducing hazardous compounds into the areas they clean.



Sulfur compounds are the predominant odor constituent and are characterized by a strong, pungent odor that can be identified from great distances. These odorous compounds can be produced at wastewater treatment facilities, industrial food processors, holding tanks, kill plants, rendering facilities, and large oil refineries. The concentration of sulfur compounds are dependent upon several factors such as temperature, weather, wind flow, microorganism count, and residence time in treatment processes. Some odorous compounds are considered offensive even at low concentrations. For example, ammonia at 2-5 ppm and mercaptans as low as 1 ppm.

Although this rendering facility was extremely well maintained and clean, showing no signs of odor due to lack of maintenance or neglect, community odor complaints were being received by facility management due to air discharge. That air was discharged in five key locations: 1. high intensity scrubber, 2. feather plant air scrubber, 3. centrifuge area, 4. anoxic pond clean out, and 5. cross flow scrubber.

Our Solution

Our Solution

1. High Intensity Scrubber

In this very specific industrial odor control scenario, Aulick recommended the use of Sul-Fight at this rendering facility in order to remove sulfur compounds. Sul-Fight was directly fed into the high intensity scrubber using a metering pump. During the original trial, Sul-Fight was fogged directly into the influent air of the room air scrubber. After further testing at another rendering facility in a different state, Aulick recommend Sul-Fight to be fed just prior to the high intensity scrubber (fogging the Sul-Fight was no longer necessary). Sul-Fight was injected directly into the middle of the air stream using an injection quill.

Part two of the use of Sul-Fight would be to increase the pH in the high intensity scrubber. For complete effectiveness of Sul-Fight, a pH of 9.0-9.5 should be maintained. Results from the additional rendering facility (out of state) testing showed that adjusting the pH in the high intensity scrubber is more cost effective due to lower volume of recirculation water to be pH controlled (an OdaLog unit was used to monitor hydrogen sulfide levels and a sniff tube was installed on the discharge of the room air scrubber).

2. Feather Plant Air Scrubber

The feather plant air scrubber’s air temperature was well managed making odor control possible. The cooling chamber was the most crucial piece of equipment in the feather plant air scrubber. The recommended injection point for fogging Sul-Fight into the air stream was the recirculation chamber as compared to the duct work prior to the recirculation chamber.

Previously, there was fallout of Sul-Fight prior to reaching the recirculation chamber where the pH was adjusted. The new fog point prevented premature fallout. As stated, the pH of the water in the recirculation chamber was adjusted to 9.0-9.5. Aulick’s Sul-Fight feed rate was 5 gallons per day and a sniff tube was installed off the discharge stack for monitoring results.

3. Centrifuge Area

It was mentioned that the centrifuge area would discharge its air into the cross flow air scrubber. Based on extensive testing, the cross flow air scrubber did not require Sul-Fight treatment. Aulick was convinced that if the centrifuge area discharged into the cross flow air scrubber, it would then require Sul-Fight treatment (it was most cost effective to discharge the centrifuge air into the current feather scrubber). OdaLog testing was conducted near the centrifuge area to determine the added loading to the feather plant air scrubber to determine Sul-Fight feed.

4. Anoxic Pond Clean Out

Aulick recommended the use of our ProFlo VDS during the anoxic pond clean out procedure. The ProFlo VDS utilizes vapor technology, high volume distribution fans and consists of a regenerative blower that vaporizes the ROX-92 in the vapor chamber. The charged air is then delivered to two high volume distribution fans that oscillate to cover 15,000 square feet. Placement of the ProFlo VDS is on the south side of the pond so that a vapor wall can be achieved. The prevailing wind shown on the diagram on the next page will ensure full contact with odors coming off the pond.

5. Cross Flow Scrubber

Data collected in the trial and testing period didn’t warrant the need for Sul-Fight in the Cross Flow Scrubber. We will continue to periodically monitor it and evaluate use of Sul-Fight if data indicates a problem.

Learn more: Sul-Fight

Our Results

Our Results

The specific results from this case study have been withheld as proprietary.

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