Evaluation of Ammonia Emission Reduction Performance and Scrubbing Water Replacement timing of a Wet Scrubber under Different Exhaust Fan Operating Rate in a Swine Barn

The performance of a wet scrubber is influenced by ammonia loading associated with changes in swine barn ventilation rate and the timing of scrubbing water replacement; however, studies evaluating these factors under field-operating conditions remain limited. In this study, a water-based wet scrubber installed in a mechanically ventilated enclosed swine barn was evaluated under four ventilation fan operation rates, 30%, 50%, 70%, and 100%, simulating seasonal ventilation conditions. The basic performance, ammonia emission reduction efficiency, and changes in scrubbing water characteristics were assessed. Ammonia concentrations at the inlet and outlet air of the wet scrubber were continuously measured over 14 days for each condition, and ammonia emissions were calculated based on measured ventilation rates. As a result, the L/G ratio ranged from 0.72 to 2.23L/m³, which was within the recommended range reported in previous studies. The ammonia emission reduction efficiencies at exhaust fan operating rates of 30%, 50%, 70%, and 100% were 40.75%, 52.09%, 57.90%, and 60.58%, respectively. And the concentrations of ammonium nitrogen and electrical conductivity (EC) in the scrubbing water increased over the operation period, with the highest values observed under the 100% fan operation condition. Electrical conductivity showed potential as a practical indicator of scrubbing water condition, and its saturation indicates a reduced capacity for ammonia absorption. Based on the EC saturation observed on day 11 under the 100% fan operation condition, the replacement timing of scrubbing water for other fan operation rates was estimated. The results indicated that saturation would respectively occur after an additional 35, 37, and 9 days at exhaust fan operating rates of 30%, 50%, and 70% beyond the 14-day experimental period for the respective conditions. This study quantified the ammonia emission reduction performance of a wet scrubber under varying ventilation conditions based on ammonia emission rates and proposed a method for estimating scrubbing water replacement timing using EC saturation levels. These findings provided practical implications for decision-making in scrubbing water management to maintain wet scrubber performance under field conditions.