Phillip Moore, USDA ARS researcher, has designed a scrubber for cleaning the exhaust from poultry and swine buildings. A solution of aluminum sulfate (alum) and water cascades down a series of wooden slats, grabbing the ammonia and dust in the exhaust air as it moves through the liquid. The scrubber is capable of removing more than 10 pounds of ammonia in a 24-hour period, and the alum solution with the trapped dust and ammonia can be spread on fields to provide nitrogen fertilizer.
The prototype scrubber is made of wood, and each exhaust fan would require its own scrubber. Moore reports that the prototype costs around $1,000 for the materials. The design has been patented, and he said that, once molds are made, a Plexiglas scrubber could be made for around the same price as the cost of the prototype.
Moore said that the scrubber reduces fan efficiency by around 30 percent. If timer fans are being scrubbed, then more horsepower would have to be put on timer fans. If all of the fans are being scrubbed, then the total amount of fans or fan motor horsepower would have to be increased.
The current design does not allow for use in freezing weather, but Moore is working on that. “Right now we don't have a heater built in, but should be able to include one for about $100 to $150. We are considering two types; a glass encased heater similar to that used in aquariums, and a blanket type heater that would be underneath the scrubber,” Moore said.
The scrubber solution that Moore has been testing is comprised of 25 gallons of liquid alum and 55 gallons of water. “We are testing other compounds at present to see what is the most cost-effective,” Moore said.
If air emissions from poultry houses become regulated, then scrubbers may become commonplace. In the absence of regulations, scrubbers for poultry house exhaust could become an option for helping provide relief for growers who have neighbor issues.