Shown above is a new scrubbing device from ARS that filters the air vented from animal rearing facilities, reducing the output of ammonia, pathogens and fine particulates. The "wet" scrubber uses a cascading solution of aluminum chloride (visible in lower photo) to grab ammonia, a form of nitrogen, from the air. In a 24-hour period, it can trap over 10 pounds of nitrogen, which may then be reused as fertilizer.

Philip Moore, who works in the agency's Poultry Production and Product Safety Research Unit, has developed and patented a simple scrubber that cleans air exhausted from poultry houses, as well as from facilities where swine are raised.

Ammonia can be problematic in these buildings, especially during the winter months when operators are trying to conserve heat. High concentrations of the gas have been known to cause health problems in birds, including an increased vulnerability to viral diseases, reduced growth rate, decreased egg production and blindness.

Besides its offending odor, high levels of ammonia gas are also detrimental to agricultural workers. And when ammonia escapes into the atmosphere, it can contribute to acid rain and increase the amount of nitrogen entering fragile aquatic systems, which can instigate troubling algal blooms.

Recent reviews conducted for the U.S. Environmental Protection Agency indicate that animal manure is one of the largest sources of atmospheric ammonia in the United States.

Moore's "wet scrubber" is designed so that a solution of aluminum sulfate, or alum, cascades down a series of wooden slats, grabbing ammonia, dust and pathogens in the air as it goes. It's capable of netting more than 10 pounds of nitrogen—as ammonia—in a 24-hour period. This nitrogen can then be applied as fertilizer to nearby pastures and fields.

The key to the recently patented system is the alum, a proven ammonia and phosphorus combatant whose antipolluting powers Moore discovered 14 years ago. While alum is already being used to help raise 700 million chickens each year in the United States, new air-filtering technologies, being explored by ARS researchers, are needed.