A new approach for minimizing ammonia emissions from poultry houses

The paper describes a novel approach to reduce ammonia emissions from Concentrated Animal and Feeding Operations (CAFO) in general, and from poultry houses in particular. The approach is based on installing a dedicated air capturing system on the feeding infrastructure that draws air from close to the litter. Air at these locations has NH3(g) concentrations an order of magnitude higher than at the vents of the ventilation system. Moreover, while the dedicated waste air drawing system can work continuously, the operation of the ventilation system is intermittent and directed towards maintaining the birds climatically-comfort. The NH3(g) rich waste air is conveyed to an acidic (0<pH<similar to 5) bubble column reactor in which ammonia is converted to NH4+. The reactor operates in a batch mode, starting at pH0 (1N HCl solution) and is switched to a new acidic absorption solution just before NH3(g) breakthrough occurs, at around pH 5. Experiments with a wide range of NH3(g) concentrations showed that the absorption efficiency is practically 100% throughout the process as long as the face velocity is below 4 cm/s. The advantages of the method include high absorption efficiency, lower NH3(g) concentrations in the vicinity of the birds, generation of a valuable product (a high concentration ammonia solution) and the separation between the ventilation and ammonia treatment systems. A small scale pilot operation conducted for 5 weeks in a broiler house showed the approach to be technically feasible. A larger scale pilot study is required for fine-tuned cost estimation.