Maintaining indoor air quality is a constant concern for poultry producers. In particular, ammonia levels within houses are a health concern for poultry and workers. But what about the ammonia in exhausted air?
Producers rely on ventilation systems and feeding adjustments to minimize ammonia in poultry houses. Now, a novel technology is providing answers to address the environmental concern of exhausted air and also comes with an economic advantage.
During a May 2025 webinar sponsored by the University of Georgia, Lingying Zhao, PhD, agriculture air quality specialist and Extension educator at The Ohio State University, presented her research on spray acid wet scrubber technology to remove and recover ammonia from large layer-poultry facilities.
Ammonia in exhausted air
Animal production contributes about 80% of human activity-related ammonia (NH3) emissions to the atmosphere, Zhao noted. Capturing this ammonia and transforming it into a usable fertilizer would be an environmental and economic win.
“Wet scrubbers use water and/or chemicals to ‘scrub’ air pollutant-laden air streams leaving buildings,” Zhao said. She explained that in Ohio’s large egg-production facilities, manure is removed from the poultry houses and stored in indoor composting facilities, and the exhaust streams from compost buildings contain large amounts of ammonia. At one composting facility, her team estimated the NH3 concentration to be 100,000 to 400,000 parts per million (ppm) and the annual emissions to be approximately 100 tons.
Wet scrubbers efficiently remove and recover NH3, Zhao said, but the packed bed-scrubber technology widely utilized in Europe will not work with ventilation systems in the US because of the high back pressure created. Therefore, Zhao and her team set out to design a scrubber system that is compatible with US ventilation systems.
Spray acid wet scrubbers
Zhao’s scrubber design can achieve removal-NH3 efficiencies of 63% to 87% at 100 to 400 ppm inlet NH3 concentrations. “On farms, this design is 70% effective in capturing the ammonia and transforming it into a usable liquid fertilizer,” she said.
Zhao explained that this novel technology removes ammonia from the exhaust gas streams. “The process involves dividing the gas into multiple separate streams and spraying liquid sulfuric acid solution into these streams. The sprayed acid reacts with the ammonia in the gas, forming a liquid ammonium sulfate solution. This method is efficient at gas ammonia concentrations of 100 to 400 ppm.”
While she acknowledged that several environmental conditions impacted the wet scrubber’s efficiency, such as NH3 concentration, relative humidity and air temperatures, Zhao believes her team’s technology and design have several advantages over existing solutions:
- Integration: compatibility with current animal production ventilation systems enables easy adoption and implementation
- High efficiency: able to effectively remove ammonia at low concentrations
- Environmentally beneficial: captures ammonia in the form of an ammonium sulfate solution, leading to recycling nitrogen and producing a needed and valuable liquid fertilizer
- Cost-effective: straightforward design and minimal equipment requirements offer a cost-effective solution for ammonia-emission control
- Scalability: suitable for various gas stream volumes, and the technology can be adjusted for different facilities and various industries
Zhao’s research demonstrated an economic breakeven point after 1 year of operation, with gains thereafter from the sale of ammonium fertilizer. She also mentioned that this technology has multiple commercial applications and can be applied across numerous industries beyond animal agriculture, including managing ammonia emissions produced by waste treatment and management, as well as industrial processes.
“With its innovative approach to ammonia-emission reduction, our technology offers a reliable and efficient solution for the poultry industry and others that are seeking to enhance environmental sustainability and meet regulatory compliance standards,” Zhao said.
