The scientists from North Carolina State University and West Virginia University have incorporated a biofilter and a heat exchanger into a single unit to reduce ammonia emissions from livestock barns, while also tempering — or heating up — the fresh air that is pumped into the barns.
The researchers showed that their design is effective under real-world conditions, operating their prototype in a 5,000-bird chicken house. The prototype removed up to 79 per cent of ammonia and reduced the energy needed to maintain the necessary temperature in the facility — recovering as much as 8.3KW of heat.
The warm polluted air from the livestock facility is cleansed by passing it through a bacteria-doped organic substance, such as compost or wood chips. The bacteria used in the biofilter interact with the pollutants and break them down into less harmful constituents.
In addition, some of the extracted warm air is transferred to the heat exchanger, where it is used to warm up cold fresh air entering from the outside.
The prototype also produces its own heat within the biofilter as a result of the heat-generating biochemical reactions that occur, for example, when ammonia is converted into nitrate by bacteria.
‘The technology is best suited for use when an operation wants to vent a facility that has high ammonia concentrations and pump in cleaner air in preparation for a fresh batch of chicks or piglets — particularly in cold weather. It is also suitable for use when supplemental heat is required for raising the young animals,’ said Dr Sanjay Shah, lead author on a paper describing the research.
Maintaining the appropriately high temperature is important for chicken and swine operations, because it is essential for rearing chicks and piglets to maturity.
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